US20080066535A1 - Adjustable Testing Tool and Method of Use - Google Patents

Abstract

Methods and systems for testing a subterranean formation penetrated by a wellbore are provided. A testing tool has a plurality of packers spaced apart along the axis of the tool, and at least a testing port. The testing tool is positioned into the wellbore and packers are extended into sealing engagement with the wellbore wall, sealing thereby an interval of the wellbore. In some embodiments, the wellbore interval sealed between two packers is adjusted downhole. In one embodiment, the location of the testing port is adjusted between two packers. The methods may be used to advantage for reducing the contamination of the formation fluid by fluids or debris in the wellbore.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• The present application is a non-provisional application of co-pending provisional application No. 60/845,332 filed on Sep. 18, 2006, and relates to co-pending and commonly assigned U.S. patent application Ser. No. 11/562,908 filed Nov. 22, 2006; U.S. patent application No. 60/882,701 filed Dec. 29,2006; and U.S. patent application No. 60/882359 filed Dec. 28, 2006, the disclosures of which are hereby incorporated herein by reference for all purposes.
TECHNICAL FIELD
• The present invention relates to well testing tools and method of use. More particularly, the invention relates to testing tools having a plurality of packer elements and at least a testing port on the tool body.
BACKGROUND OF THE INVENTION
• Advanced formation testing tools have been used for example to capture fluid samples from subsurface earth formations. The fluid samples could be gas, liquid hydrocarbons or formation water. Formation testing tools are typically equipped with a device, such as a straddle or dual packer. Straddle or dual packers comprise two inflatable sleeves around the formation testing tool, which makes contact with the earth formation in drilled wells when inflated and seal an interval of the wellbore. The testing tool usually comprises a port and a flow line communicating with the sealed interval, in which fluid is flown between the packer interval and in the testing tool.
• Examples of such tools are schematically depicted inFIGS. 1A to 1D.FIG. 1A shows an elevational view of a typical drill-string conveyed testing tool10a .Testing tool10ais conveyed by drill string13aintowellbore11 penetrating asubterranean formation12. Drill string13ahas a central passageway that usually allows for mud circulation from the surface, then through downhole tool10a,through the bit20 and back to the surface, as known in the art. Testing tool10amay be integral to one of more drill collar(s) constituting the bottom hole assembly or “BHA”. Testing tool10ais conveyed among (or may itself be) one or more measurement-while-drilling or logging while the tool(s) known to those skilled in the art. In some cases, the bottom hole assembly is adapted to convey a casing or a liner during drilling. Optionally, drill string13aallows for two-way mud pulse telemetry between testing tool10aand the surface. A mud pulse telemetry system typically comprises surface pressure sensors and actuators (such as variable rate pumps) and downhole pressure sensors and actuators (such as a siren) for sending acoustic signals between the downhole tool and the surface. These signals are usually encoded, for example compressed, and decoded by surface and downhole controllers. Alternatively any kind of telemetry known in the art may be used instead of mud pulse telemetry, such as electro-magnetic telemetry or wired drill pipe telemetry. Tool10amay be equipped with one or more packer(s)26a,that are preferably deflated and maintained below the outer surface of tool10aduring the operations. When testing is desired, a command may be sent from the surface to the tool10avia the telemetry system. Straddle packer26acan be inflated and extended toward the wall ofwellbore11, achieving thereby a fluid connection between theformation12 and the testing tool10aacrosswellbore11. As an example, tool10amay be capable of drawing fluid fromformation12 into the testing tool10a,as shown by arrows30a.Usually one or more sensor(s) located in tool10a,such as pressure sensor, monitors a characteristic of the fluid. The signal of such sensor may be stored in downhole memory, processed or compressed by a downhole processor and/or send uphole via telemetry. Note that in some cases, part of tool10amay be retrievable if the bottom hole assembly becomes stuck in the wellbore, for example by lowering a wireline cable and a fishing head.
• FIG. 1B shows an elevational view of a typical drill-stem conveyed testing tool10b.Testing tool10bis conveyed by tubing or drill pipe string13bintowellbore11 penetrating asubterranean formation12. Tubing string13bmay have a central passageway that usually allows for fluid circulation (wellbore fluids or mud, treatment fluids, or formation fluids for example). The passageway may extend through downhole tool10b,as known in the art. Tubing or drill string13bmay also allow for tool rotation from the surface. Testing tool10bmay be integral to one or more tubular(s) screwed together. Testing tool10bis conveyed among (or may be itself) one or more well testing tool(s) known to those skilled in the art, such as perforating gun. The testing tool10bmay be lowered in an open hole as shown, or in a cased wellbore. In some cases, tubing string13ballows for two-way acoustic telemetry between testing tool10band the surface, or any kind of telemetry known in the art may be used instead, including conductive tubing or wired drill pipe. Tool10bmay be equipped with one or more packer(s)26bthat is usually retracted (deflated) during tripping of testing tool10b.When testing is desired, tool10bmay be set into testing configuration, for example by manipulating flow in tubing string13b.Extendable packer26bcan be extended (inflated) toward the wall ofwellbore11, achieving thereby a fluid connection between an interval offormation12 and the testing tool10bacrosswellbore11. As an example, tool10bmay be capable of drawing fluid fromformation12 into the testing tool10b,as shown byarrows30b.Usually one or more sensor(s) located in tool10b,such as pressure or flow rate sensor, monitor(s) a characteristic of the fluid. The signal of such sensor may be stored in downhole memory, processed or compressed by a downhole processor and/or send uphole via telemetry. Note that in some cases part of tool10bmay be a wireline run-in tool, lowered for example into the tubing string13bwhen a test is desired.
• FIG. 1C shows an lavational view of a typical wireline conveyed testing tool10c.Testing tool10cis conveyed bywireline cable13cinto wellbore11 penetrating asubterranean formation12. Testing tool10cmay be an integral tool or may be build in a modular fashion, as known to those skilled in the art. Testing tool10cis conveyed among (or may be itself) one or more logging tool(s) known to those skilled in the art. Preferably the wireline cable13callows signal and power communication between the surface and testing tool10c.Testing tool10cmay be equipped with straddle packers26c,that are preferably recessed below the outer surface of tool10cduring tripping operations. When testing is desired, straddle packer26ccan be extended (inflated) toward the wall ofwellbore11 achieving, thereby, a fluid connection between an interval offormation12 and the testing tool acrosswellbore11. As an example, tool10cmay be capable of drawing fluid fromformation12 into the testing tool10c,as shown by arrows30c.Examples of such tools can be found U.S. Pat. No. 4,860,581 and U.S. Pat. No. 4,936,139, both assigned to the assignee of the present invention, and incorporated herein by reference. Note in some cases that wireline tools (and wireline cable) may be alternatively conveyed on a tubing string, or by a downhole tractor (not shown). Note also that the wireline tool may also be used in run-in tools inside a drill string, such as the drill string shown inFIG. 1A. In these cases, the wireline tool10cusually sticks out of hit20 and may perform measurements, for example when the bottom hole assembly is pulled out ofwellbore11.
• FIG. 1D shows an elevational view of another typical wireline conveyed testing tool10d.Testing tool10dis conveyed by wireline cable13dintowellbore11 penetrating asubterranean formation12. This time wellbore11 is cased with acasing40. Testing tool10dmay be equipped with one or more extendable (inflatable) packer(s)26d,that are preferably recessed (deflated) below the outer surface of tool10dduring tripping operations. Tool10dis capable of perforating thecasing40, usually below at least one packer (see perforation41), for example, the tool could include one or more perforating gun(s). InFIG. 1D, the testing tool10dis shown drawing fluid fromformation12 into the testing tool10d(see arrows30d). Usually one or more sensor(s) is located in tool10d,such as a pressure sensor, monitors a characteristic of the fluid. The signal of such sensor is usually send uphole via telemetry. Note that in some cases, tools designed to test a formation behind a casing may also be used in open hole. Note also that cased formations may be evaluated by downhole tool conveyed by other means that wireline cables.
• Typical tools are not restricted to two packers. Downhole systems having more than two packers have been disclosed for example in patents U.S. Pat. No. 4,353,249, U.S. Pat. No. 4,392,376, U.S. Pat. No. 6,301,959 or U.S. Pat. No. 6,065,544.
• In some situations, a problem occurs when fluid is drawn into the tool through openings along the tool body. Formation fluids, wellbore fluids and other debris from the wellbore may occupy the volume between the upper sealed packer and the lower sealed packer. This causes various fluids to enter the same openings (or similar openings) located in the sealed volume. Moreover, when the density of the wellbore fluid is larger than the density of the formation fluid, it is very difficult to remove all of the wellbore fluid since there will be a residual of wellbore fluid that resides between the lowest opening and the lowest packer, even after a log pumping time. Thus, these wellbore fluids can contaminate the formation fluid entering the tool.
• Downhole systems facilitating the adjustment of the flow pattern between the formation and the interior of the tool have been disclosed for example in patent application US 2005/0155760. These systems may be used to reduce the contamination of the formation fluid by mud filtrate surrounding the wellbore. Note that methods applicable for reducing the contamination by mud filtrate surrounding the wellbore are not always applicable for reducing the contamination by fluids and other debris from the wellbore.
• Despite the advances in formation testing, there is a need for improved testing methods utilizing a tool having plurality of packers spaced apart along the axis of the tool, and at lest a port on the tool body located between two packer elements. Such methods are preferably capable of reducing the contamination of the formation fluid by fluid or debris in the wellbore. These methods may comprise adjusting in situ the length of a sealed interval between two packer elements. Alternatively, these methods may comprise adjusting the location of the port within a packer interval.
SUMMARY OF THE INVENTION
• Methods and systems for testing a subterranean formation penetrated by a wellbore are provided. A testing tool has a tool body, a plurality of packer elements spaced apart from one another along the longitudinal axis of the tool body, and at least a testing port on the tool body located between two packer elements. The testing tool is positioned into the wellbore and packers are extended into sealing engagement with the wellbore wall, sealing thereby an interval of the wellbore. Fluid is flown between the sealed interval and the testing tool through the testing port.
• In at least one aspect, the invention relates to a method that comprises the steps of selecting in situ the length of an interval of the wellbore to be sealed, and extending at least two packer elements. The length of the interval of the wellbore that is sealed by extending the packer elements is substantially equal to the selected length.
• In another aspect, the invention relates to a method that comprises the step of extending at least two packer elements into sealing engagement with the wellbore wall, sealing thereby a first interval of the wellbore. The method also comprises the step of extending another packer element into sealing engagement with the wellbore wall, sealing thereby a second interval of the wellbore.
• In yet another aspect, the invention relates to a method that comprises the step of adjusting a port on a testing tool.
• In yet another aspect, the invention relates to a system for testing a subterranean formation penetrated by a wellbore. The system comprises a testing tool and a snorkel assembly adaptable on the testing tool. The snorkel assembly comprises a snorkel port and a fluid communication between the port on the tool body and the snorkel port, the snorkel port and the tool port being substantially offset from each other.
• The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.
BRIEF DESCRIPTION Of THE DRAWINGS
• For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
• FIGS. 1A-1D are elevation views showing typical examples of downhole testing tools, where the testing tool is drill string conveyed inFIG. 1A, tubing string conveyed inFIG. 1B, and wireline conveyed inFIGS. 1C and 1D.
• FIG. 2 is a schematic showing one embodiment of a testing tool capable of scaling wellbore intervals of various lengths;
• FIG. 3 is a schematic illustrating the selective length adjustment of a sealed wellbore interval with a tool having a plurality of spaced apart packer elements;
• FIG. 4 is a schematic illustrating the selective adjustment the length of a sealed wellbore interval with a tool having a slidable packer element;
• FIGS. 5A-5B are cross sectional views showing embodiments of a snorkel assembly adapted to a testing tool;
• FIGS. 6A-6B show a flow chart describing the steps involved in one embodiment of a method for testing a subterranean formation;
• FIGS. 7A-7D are schematics illustrating a method for testing a subterranean formation;
• FIGS. 8A-8D are schematics illustrating another a method for testing a subterranean formation; and
• FIGS. 9A-9B are schematics illustrating yet another method for testing a subterranean formation.
DETAILED DESCRIPTION
• Certain examples are shown in the above identified figures and described in detail below. In describing these examples, like or identical reference numbers are used to identify common or similar elements. The figures are not necessarily to scale and certain features and certain view of the figures may be shown exaggerated in scale or in schematic for clarity and/or conciseness.
• FIG. 2 shows one embodiment of a testing tool capable of sealing wellbore intervals of various lengths. Thetesting tool10 is conveyed withinwellbore11 created information12 via conveyance mean13. Thetesting tool10 can be conveyed downhole using a wireline cable after the well has been drilled and the drill string removed from the wellbore. Alternatively, the testing tool can be conveyed downhole on the drill string used to drill the wellbore. Any conveyance mean known in the art can be used to convey thetool10. Optionally, the conveyance mean allows for two ways communication betweentool10 and the surface, typically a surface monitor (not shown), via a telemetry system as known by those skilled in the art. When used with some conveyance means,tool10 may accommodate for mud circulation through the tool (not shown), as well known by those skilled in the art. As shown inFIG. 2, thetesting tool10 is build in a modular fashion, with telemetry/electronics module154,packer module100, downhole fluid analysis module151,pump module152, and carrier module153. Telemetry/electronics module154 may comprise acontroller140, for controlling the tool operation, either from instructions programmed in the tool and executed by processor140aand stored in memory140b,or from instruction received from the surface and decoded by telemetry system140c.Controller140 is preferably connected to valves, such asvalves110,111,112,113,114,115 and116 via one or more bus190 running through the modules oftool10 for selectively enabling the valves.Controller140 may also control apump130, collect data from sensors (such as optical analyzer131), store data in memory140bor send data to surface usingtelemetry system140c.the fluid analysis module151 may include an optical analyzer131, but other sensors such as resistivity cells, pressure gauges, temperature gauges, may also be included in fluid analysis module151 or in any other locations intool10.Pump module152 may comprise thepump130, which may be a bidirectional pump, or an equivalent device, that may be used to circulate fluid along the tool modules via one ormore flow line180. Carrier module153 can have a plurality of cavities, such as cavities150-1,150-2, to150-nto either store samples of fluid collected downhole, or transport materials from the surface, as required for the operation oftool10.Packer elements102,103,104 and105 are shown uninflated and spaced along the longitudinal axis ofpacker module100. Although not shown, the packers extend circumferentially aroundtool100 so that when they are inflated they will each form a seal between the tool and awellbore wall15.
• Also shown onFIG. 2 areparticle breaking devices160,161, or162. These particle breaking devices could be focused ultrasonic transducers or laser diodes. Particle breaking devices are preferably used to pulverize sand, or other particles passing into the flow lines, into smaller size particle, for example, for avoiding plugging of component of the testing tool. These devices may use different energy/frequency levels to target various grain sizes. For example,particle breaking device162 may be used to break produced sand during a sampling operation. In some cases, the readings of downhole sensor131 will be less affected by pulverized particles than larger size particles. In another example, particle breaking device163 may be used to break particles in suspension in the mud during an injection (fracturing) operation. In some cases, pump130 will be able to handle pulverized particles more efficiently and will not plug, leak or erode as fast as with larger size particles in the mud. Particle breaking devices may be used for other applications, such as transferring heat to the flow line fluid.
• Whiletesting tool10, as shown inFIG. 2, is build in a modular fashion, those skilled in the art will appreciate that all the components oftool10 may be packaged in a single housing. Also, the arrangement of the modules inFIG. 2 may be modified. For example, fluid analysis module151 shown abovepump module152 may alternatively be located betweenpump module130 and carrier module153. In some situation,tool10 can have additional (or fewer) operational capabilities beyond what is discussed herein. The tool can be used for a variety of testing, sampling and/or injection operations using the selectively enabled packer elements as discussed herein.
• FIG. 3 shows in more details an embodiment ofpacker module200 similar tomodule100 ofFIG. 2, where two of the four packer elements have been inflated. Packer module ortool portion200 may comprise one ormore flow line280, similar toflow line180 inFIG. 2.Flowline280 is selectively connected to one or more port(s) in the tool, such as ports252,253a,253band254 via associatedvalves242,243a,243band244 respectively, allowing fluid to flow from or intoflow line280. Each interval betweenpacker elements262,263,264 and265 has preferably at least one port. Although shown on the same side of the tool, ports may be located anywhere around the tool. Packer module ortool portion200 may also comprisepacker inflation devices212,213,214 and215 for selectively inflate or deflatepackers262,263,264, and265 respectively. Other means to extend packers into sealing engagement with the wellbore wall may also be used without departing from the invention.Inflation devices212,213,214 and215 may consist of one or more pump(s), controlled by a controller (not shown) via bus290, similar to bus190 ofFIG. 2.
• Note thattesting tool10 may not be modular. In this eventualityFIG. 3 would represent a portion oftesting tool10. Note also that the concepts discussed herein are not limited to four packer elements. Any number of packer elements may be deployed on a tool and selectively inflated depending on desired results and the operations to be performed. Also note that the packer elements need not be all of the same type or spaced equidistant from each other.
• Each of thepackers262,263,264 and265 can be inflated so that the packers radially expand and contactwellbore wall15 offormation12. By expanding at least two of the packers sufficiently to contact the wellbore wall, the interval of the wellbore between the two inflated packers can be sealed off from the rest of the wellbore. Thus, as shown inFIG. 2,packers263 and265 have been selectively inflated to form a sealedinterval221 betweenpackers263 and265. The sealed interval allows, for example, formation fluid to be drawn into the tool for testing. The selective enabling of each packer can be, for example, by expanding the packer under the control ofinflation devices212,213,214 and215 by hydraulic lines extending into the packer element. Note that while each packer is shown with an individual inflation device, a device common to each packer can be used. Also, the force for enabling the packers can come from the surface or from another tool, if desired.
• Other packers may be selectively extended to seal wellbore intervals of various lengths. An interval length may be selected downhole, for example by analyzing measurements performed by sensors oftool10 or from another tool in the tool string. A measurement that may be used in some cases could be a wellbore resistivity image. By way of example, the longest testing interval may be selected. Sampling a long interval of wellbore wall in this way could result in a lower drawdown pressure. The user (or some logic implemented downhole) would then enablepackers262 and265, for example by activatinginflation devices212 and215 through bus290. Packers262 and264 would not be enabled and would remain retracted (deflated). By extendingpackers262 and265, the wellbore interval between top packer262 andbottom packer265 would be sealed. Testing would follow. For example, this may include injecting or drawing fluid from any of the ports252,253a,253bor254 by opening any of the associatedvalves242,243a,243bor244 respectively. Alternatively, a short testing interval may be selected. Sampling a short interval of wellbore wall in this way could result in a more homogenous fluid. For example, it may be desirable to only test an interval having a length almost equal to the distance betweenpackers263 and264. This can be done by extendingpackers263 and264 toward the wellbore wall and sealing the corresponding interval. Note that by having non-equal spacings between three or more packers, the user can choose among a variety of interval length to be sealed and test the formation.
• In some testing applications, monitoring the flow of fluids in the formation (injected from the tool or drawn into the tool) maybe desirable. In some situations, it can be advantageous to have sensors, such has sensors201, close thewellbore wall15. In one embodiment,sensors201a,201b,201cand201dmay be located directly on the packers. These sensors can measure various formation or fluid properties while the tool is in the wellbore. For simplification.FIG. 3 illustrates sensors201a-201donly onpackers263 and265. However, the sensors may also be located on any or all of the packers. In addition to locating the sensors on the packers, other sensors202, such as sensors202a,202b,and202c,may be located on or within the tool at any location. Some of these sensors201,202 may measure fluid properties (such as pressure, optical densities) while others may measure formation properties (such as resistivity, sigma, carbon-oxygen ratio, sonic travel time). Data gathered by sensors201a-dand202a-c(and other sensors) may be communicated via bus290 to a controller (not shown) similar to thecontroller140 ofFIG. 2. The data sent to the controller may further by processed downhole by a processor, similar to the processor140aofFIG. 2. The controller may further adjust operations of thetool10, for example modify the pumping rate ofpump130 or modifying the length of the sealed interval, based on the processed data. Data gathered by sensors201,202 may also be stored downhole into a memory, similar to the memory140bofFIG. 2, or sent uphole for analysis by an operator via a telemetry system, similar to the telemetry system140cofFIG. 2.
• Perforation may be desirable for some testing applications. Thus, the formation may further be perforated at a point within the sealed off interval of the wellbore, for example, for altering the fluid flow from the formation to the sealed interval of the wellbore between the two inflated packers. Any kind of perforation device may be mounted between two inflatable packers, such asperforation guns230 and231. For example, a bullet fired from a perforatinggun230 may be used to perforateformation12 as shown inFIG. 3 to create a perforation222. The bullet may hold a sensor capable of sending data totool10, for example using an electromagnetic wave communication.
• FIG. 4 shows another embodiment of a testing tool capable of selecting in situ the length of an interval to be sealed. Thus,FIG. 4 illustrates the selective length adjustment of a sealed wellbore interval by sliding a packer element along the length of the tool to vary the distance between two packer elements. Referring toFIG. 4,packer module300 similar topacker module100 ofFIG. 2 is shown.Packer module300 is shown with threepacker elements360,361 and362 but any number of packers could be employed. These three packer modules are operatively coupled with threeinflation devices310,311 and312 respectively for selectively extending (inflating) and recessing (deflating) the three packer elements. Theinflation devices310,311 and312 may be communicatively coupled to a downhole controller via a bus390, similar to bus190. In the embodiment ofFIG. 4, themiddle packer361 is shown to be slidably movable along the longitudinal axis of thetool10.Packer element361 is coupled topiston actuator302 which may be utilized to slidepacker361 up or down the length of the tool body. For example,actuator302 could be used to movepacker361 toposition361. The fluid for inflating/deflating the packer could be delivered by inflation device311 topacker361, for example, via hydraulic line located in ram303 (not shown).
• In operation,testing tool10 ofFIG. 4 would be lowered intoformation12 traversed bywellbore11. The length of an interval ofwellbore11 to be sealed can be determined in situ. For example, a Nuclear Magnetic Resonance measurement can be used to estimate the viscosity of the formationfluid surrounding tool10, and the length of the interval to be sealed for a sampling operation may be adjusted therefrom. Thepiston actuator302 may then be activated for slidingpacker element361 along the tool body for adjusting the distance betweenpacker element360 andpacker element361. For example, once the length is selected (packer element361 is moved to position361′ onFIG. 4),packer elements360 and361 may be extended (inflated) toward thewellbore wall15 by inflation devices310 and311, sealing thereby an interval of the wellbore which length is substantially equal to the selected length. Testing may then begin. For example, fluid may be drawn into the tool through port351. The testing step may involve manipulating valves, such asvalve341. Fluid may be flown into flowline380 (similar toflowline180 inFIG. 2). When testing is finished, packers are usually deflated below the outer surface of the testing tool.
• The embodiment shown inFIG. 4 can be combined with the embodiment shown inFIG. 2 orFIG. 3, such thatpackers102,103,104 and105 (FIG. 2) may all be slidably moved along the tool such that it is possible to vary the vertical distance between any two packers. As an example, it may be desirable to test a region of an earth formation larger than that covered by the area betweenpackers102 and103 but not as large as the areas covered bypackers102 and104. In this case,packer102 could be moved upward in the vertical directional along the tool to expand the top area, or packer103 may be moved downward in the vertical direction along the tool to expand the area downward. The ability to selectively move packers in the vertical direction along the tool provides an infinite number of testing regions within the well.
• Note that some packers may be slidable and some may not, as shown inFIG. 4 by nonslidable packer360 and362, andslidable packer361. Note also that slidable and non slidable packers may be arranged in various combinations. Although the operation oftesting tool10 ofFIG. 4 has been described usingpacker element360 and361 to seal an interval with a length selected downhole,packer361 and362 may be used instead, and fluid may alternatively be flown through port352 (and open valve342) ontool10.
• FIGS. 5A-5B show embodiments of a snorkel assembly401 (FIG.5A) and401′ (FIG. 5B) adapted to atesting tool10. The snorkel assembly may be used to advantage for bringing a port of the sampling tool to a more effective relative position with respect to the packer elements.FIG. 5A-5B show apacker module400 adapted on atesting tool10 lowered in awellbore11 penetrating aformation12. Note that the testing tool is shown partially, and may be similar to the testing tool ofFIG. 2. Thetesting tool10 may include controller bow springs480 and481 as known in the art. Thepacker module400 comprisespacker elements462 and463 for sealing an interval of thewellbore11 by extending (inflating) the packer elements into sealing engagement with thewellbore wall15, for example withinflation devices412 and4l3 respectively. Thepacker module400 may further comprise aport450 on the tool body and an associated valve451. The port allows for fluid communication between aflow line490 in the downhole tool, similar toflow line180 inFIG. 2, and a sealed interval of the wellbore. In the examples ofFIGS. 5A-5B twodifferent snorkel assemblies401 and401′ respectively, are adapted on thetesting tool10. Thesnorkel assembly401 or401′ may comprise afilter423, anadapter422, a snorkel421 (FIG. 5A) or421′ (FIG. 5B), and aring420. Note that the snorkel assembly may comprise additional parts, such as sensors, for providing other functionalities. Note also that the snorkel assembly may comprise fewer parts. For example thefilter423, thering420, may be optional.
• The snorkel assembly is preferably adaptable on thetesting tool10. For example, while thepacker module400 is disconnected from thetesting tool10, and thepacker element462 is not mounted on the packer module, theadapter422 may slide around the packer module body and rest on the mounted packer463. When theadapter422 is in place, theport450 of the tool is fluidly connected toannular groove431 of theadapter422. Then the snorkel421 or421′ is slid on top of theadapter422. Snorkel421 (421′) comprises one or more fluid communication(s)440 (440′) between a snorkel port430 (430′) andannular groove431 via one ormore passageway441. In the example ofFIGS. 5A-5B, fluid communication(s)440 comprise a plurality of flow lines, for example eight, distributed around the circumference of the snorkel. Ascreen filter423 may then slide around the snorkel and may be held in place with screws470 or other fasteners. Thefilter423 preferably covers the snorkel port430 (430′). Aring420 may finally be slid on the tool mandrel and locked in place before thepacker element462 is mounted. Thepacker module400 is further included intotesting tool10. Thetesting tool10 may be lowered into a wellbore to perform a test on a subterranean formation.
• Different snorkel designs may have different snorkel port configurations. The snorkel design that is adapted ontool10 is preferably chosen such that the snorkel port configuration is adjusted for a particular testing operation. In the example ofFIG. 5A, thesnorkel port430 is shown higher than thesnorkel port430′ ofFIG. 5B. Also the snorkel port shape may be adjusted from one snorkel design to another. Thus, if a snorkel port configuration such as shown by430 is desirable for testing, an operator may adapt the snorkel421 to thetesting tool10, adjusting thereby the initial configuration of the port on thetesting tool450 to the desired configuration of thesnorkel port430. In other cases, a different snorkel port configuration, such as shown by430′, may be desirable for testing. Here again, an operator may adapt a different snorkel to thetesting tool10, adjusting thereby the initial configuration of the port on thetesting tool450 to the different configuration of thesnorkel port430′.
• Screen filters with various characteristics can be assembled in the snorkel assembly. In some cases, the screen filter may comprise two or more screens. In some cases, the screens may be separated by a small gap. Also the screens can be reinforced, for example by vertical strips. The screen filter characteristics are preferably adjusted for the testing operation the tool is intended to perform.
• Note that a snorkel assembly can be adapted to any kind of testing tool, such as the testing tool ofFIG. 2,3 or4. Note also that the snorkel in the snorkel assembly could be made telescopic and may be adjusted downhole using an actuator.
• FIGS. 6A-6B describe one embodiment of amethod500 for testing a subterranean formation. Themethod500 preferably utilizes a testing tool having a tool body, a plurality of packer elements spaced apart from one another along the longitudinal axis of the tool body, and at least a testing port on the tool body located between two packer, as is the described herein. However, themethod500 may be used with any testing tool having selectively-activated packer elements and capable of formation testing.
• In optional step505, a snorkel assembly is placed on the testing tool. The snorkel assembly is capable of adjusting a port on a testing tool. The snorkel assembly may also be capable of adjusting the characteristic of a filter screen. The snorkel may further be capable of reducing the volume trapped in the sealed interval. For example, the testing tool may be intended to sample formation fluid in an unconsolidated formation, and the formation fluid is expected to have a lower density than the borehole fluid. The testing tool may also be intended for a large diameter wellbore. Such sampling situation is illustrated inFIG. 9A-9B for explanatory purposes. Note that in step505 ofmethod500, the testing tool is not yet lowered into the borehole, andFIG. 9A-9B are used therebelow to explain how the testing tool is expected to perform in the sampling situation discussed above, based on a prior knowledge of the sampling conditions, and how the adjustment of step505 may be performed.
• Referring toFIG. 9A, a portion of testing tool similar totesting tool10 ofFIG. 2 is shown in awellbore11 traversing aformation12 during a sampling operation.Packer elements862 and863 are shown in an extended position, and engaged with thewellbore wall15 for sealing a wellbore interval therebetween. In the example ofFIG. 9A, thetesting tool10 has drained fluid from the wellbore into flowline890 (similar toflow line180 ofFIG. 2) through tool port850 and open valve851. The fluid drained from the wellbore has been partially replaced byformation fluid842, and sand or debris840 produced from the formation. Note that some wellbore fluid may still be present in the sealed interval, as shown bywellbore fluid841. The illustration ofFIG. 9A assumes that debris, wellbore fluid and formation fluid have segregated in the order as shown, because of the density contrast between these materials. However segregation may occur in a different order. During the sampling operation shown inFIG. 9A, sand or debris may enter tool port850 and plug, clog or erode various components in thetesting tool10, such as pumps, or valves. Also, debris may cause noise at a fluid property sensor. Finally, the volume of the sealed interval may be large, because the testing tool is run in a wellbore of large diameter. Because of this large volume, the sampling operation may require a log time before formation fluid enters in the testing tool and is available for capture in a cavity. This long sampling time may increase the probability of the testing tool to become stuck in the wellbore.
• Turning now toFIG. 9B, asnorkel assembly800 is shown in awellbore11 traversing aformation12 during a sampling operation similar to the sampling operation shown inFIG. 9A. IbFIG. 9B the location of the tool port850 has been adjusted for this particular operation by adapting a snorkel assembly to the testing tool prior to lowering it into the borehole. Fluid is now drawn from the wellbore at the snorkel port830. Snorkel port830 is located above the debris that have segregated on top of thelower packer element863, reducing thereby the probability of components of thetool10 being plugged by debris entering thetesting tool10. Note also that the snorkel port is located close to theupper packer element862, reducing thereby the volume and the time needed to draw into the tool formation fluid that has segregated above the wellbore fluid. In the example ofFIG. 9B, the snorkel assembly also comprises a filter screen823, whose characteristics such as the area, the screen mesh size, the number of screen layers or the screen collapse resistance may have bene adjusted to the sampling operation. For example, the screen filter823 may be chosen to be a double layer filter, or may be reinforced by vertical stripes between the layers to insure a high collapse resistance. The snorkel port830 may further extend around the entire circumference of the tool, increasing thereby the area of the intake adjacent to the filter screen, which may be advantageous for avoiding plugging of the filter screen. In the example ofFIG. 9B, the outside diameter of the snorkel module has been selected so that the trapped volume of fluid betweenpacker element862 and863 is reduced with respect toFIG. 9A. Specifically, the outside diameter is selected just below the wellbore diameter. Reducing the trapped volume of fluid may decrease the volume of fluid needed to be pumped before formation fluid enters the tool and decreases the time needed to capture a formation fluid sample. Note that the volume may also be reduced by using rings, such as ring820.
• Turning back toFIGS. 6A-6B, the testing tool is lowered in the wellbore in step510. As mentioned before, the testing tool may be conveyed on a drill string, a tubing string, a wireline cable or any other means known by those skilled in the art. Lowering the downhole tool may comprise drilling or reaming the wellbore. The wellbore may be open to the formation or may be cased. If the wellbore is cased, the testing tool preferably comprises perforation devices, such as the shafts or perforating guns, for example located between two packer elements. The testing tool may be lowered in the wellbore with other tools, such as formation evaluation tools known by those skilled in the art. The conveyance means preferably comprises a telemetry system capable of sending information collected by a downhole tool to the surface, and receiving commands from the surface for controlling operation of the testing tool. A downhole controller executing instructions stored in a downhole memory in the testing tool may also control operations of the testing tool.
• Step515 inFIGS. 6A-6B determines the length of the wellbore interval to be tested. This can be achieved downhole, for example using a processor and data collected by sensors. This can alternatively be achieved under control of a user operating from the surface, for example, using a camera or other sensing tools, not shown, which are part of the downhole tool string. This can be alternatively achieved by any other methods and/or sensors mentioned therein. Other methods and/or sensors may also be used without departing from this invention. Themethod500 may comprise the optional step520, that determines whether cleaning is desired within the testing interval. Cleaning may comprise delivering materials conveyed from the surface in one of the cavity oftesting tool10, such as cavity150-1 ofFIG. 2, into the wellbore, for example for dissolving locally the mudcake on thewellbore wall15. This material could be water, steam, acid solution, solvent or any combination thereof. If cleaning is desired, optional step525 determines the length of a cleaning interval to be sealed, usually comprising the testing interval so that the cleaning material can be fully removed from the testing interval as further discussed below. The cleaning interval length may be selected by enabling the extension of two packer elements from the plurality of the packer elements carried by the testing tool in step530. Note that the adjustment of the testing interval length may alternatively be achieved by sliding packer elements along the axis of the tool prior to extending the packer element toward the wellbore wall, as previously discussed with respect toFIG. 4.
• As a way of example,FIGS. 7A-7D show a portion of a testing tool similar to testing10 ofFIG. 2, lowered in awellbore11 traversing aformation12. Thetesting tool10 comprisespacker elements602,603,604 and605, andports652,653, and654. In the example ofFIGS. 7A-7D, the extension ofpacker elements602,603,604 or605 can be selectively enabled, for example using the apparatus described in more details with respect toFIG. 3. As a way of example, the length of the wellbore interval to be sealed determined in step515 may be represented byinterval610 onFIGS. 7A-7D. As a way of example, the length of the wellbore interval to be sealed determined in step525, may be represented by interval611 onFIGS. 7B-7D.
• Turning back toFIGS. 6A-6B, packer elements of the testing tool are extended toward the wellbore wall in step535 if cleaning is desired. A first interval, the cleaning interval, is sealed from the rest of the wellbore in step540. Note that in some cases it may be advantageous to bypass one of the sealing packer element with a flow line (not shown) in the testing tool that establishes a fluid communication between the sealed interval in step540 and another part of the system, for example the wellbore outside the sealed cleaning interval. Optional cleaning or treatment is performed in step545.
• In the example ofFIGS. 7B and 7C, the interval length may be selected by enabling the extension of two selected packer elements from a plurality of packer elements carried by the testing tool.Packers602 and604 are first enabled and then extended (inflated) in step535 of the method shown inFIGS. 6A-6B. By extending toward the wellbore wall,packers602 and604 seal the cleaning interval611 which length is roughly equivalent to the determined length in step525 of themethod500 shown inFIGS. 6A-6B. A cleaningfluid660 may then be injected throughport652 or653 into the wellbore in step545 of the method shown inFIGS. 6A-6B. Preferably the cleaningfluid660 will occupy a large portion of the cleaning interval, as indicated by cleaningfluid660 inFIG. 7B. Sensors, similar to sensors202a-cor201a-dshown inFIG. 3, or other sensors, may optionally monitor the cleaning process, and the cleaning process may be controlled based on the sensor signals. Step545 may further comprise draining the cleaningfluid660, for example in port653 as shown inFIG. 7C. This cleaning fluid may be dumped into the wellbore outside the sealed interval, for example at port163 ofFIG. 2, or stored in a cavity in the testing tool, such cavity150-2 ofFIG. 2. Usually, draining through port653 will not efficiently remove the cleaningfluid660 located between the lower packer element of the sealedinterval604 and the draining port653. Note that in the example ofFIG. 7C, it is assumed that the density of the cleaning fluid and/or cleaning debris is larger than the density of the formation fluid. It is further assumed that thetesting tool10 is operated such that formation fluid is drawn from the surrounding formation as cleaning fluid is drained outside the cleaning interval, as shown byformation fluid661. Thus, formation fluid and cleaning fluid may segregate by gravity as shown inFIG. 7C. In the case the formation fluid density is higher than the cleaning fluid and/or cleaning debris density, the sequence of formation fluid, cleaning fluid, and/or cleaning debris may be different. Note also that this invention is not limited to the presence of two segregated fluids in the sealed interval.
• Turning back toFIGS. 6A-6B, the testing interval length may be selected by enabling the extension of two packer elements from the plurality of the packer elements carried by the testing tool in step550. Note that the adjustment of the testing interval length may alternatively be achieved by sliding packer elements along the axis of the tool prior to extending the packer element toward the wellbore wall, as previously discussed with respect toFIG. 4. Packer elements of the testing tool are extended toward the wellbore wall in step555. Note that if a first cleaning interval has already been sealed, it may be advantageous in some cases to maintain the first interval sealed while sealing a second interval, the testing interval. Thus, it may be advantageous to bypass one of the sealing packer element with a flow line (not shown) in the testing tool that establishes a fluid communication between the cleaning interval and another part of the system, for example the wellbore outside the sealed cleaning interval. This would allow for the fluid displaced by the extension of a third packer element in the sealed interval to be vented out of the sealed interval. A testing interval is sealed from the rest of the wellbore in step560. Testing of the formation is performed in step565, for example injection, sampling, or local interference test (also known as interval pressure transient test or IPTT) is preferably performed in a manner known in the art.
• Continuing with the example ofFIG. 7D, thetesting interval610 is selected by enabling the extension (inflation) ofpacker element603 between already extendedpacker elements602 and603 (step550 of the method inFIGS. 6A-6B). Note, that in thisscenario packer element602 would be enabled for both sealing the testing volume and the cleaning volume. Thetesting interval610 is sealed once thepacker element603 reaches the wellbore wall. Thus, thetesting interval610 is now isolated from the residual cleaning material and/ordebris660 above thelower packer604. The residual cleaning material and/ordebris660 is retained below expandedpacker603 and is trapped, so as not to contaminate the fluid contained in thetesting interval610. However, if desired,packer604 can be retracted (deflated) thereby allowing the residual cleaning material to disburse downhole if desired. Testing may then begin. Formation fluid may be drawn frominterval610 into theport652. Note that cleaningfluid660 was drained during the cleaning period through port653 andformation fluid661 is now drawn throughport652 during the testing period. This may be achieved by associatingport652 and653 with valves (not shown), similar to valves242 and243 associated respectively to ports252 and253 inFIG. 3.
• Turning back toFIGS. 6A-6B, one or more additional interval may be sealed if needed, including the option of selecting of the length of these additional intervals, as shown bystep570. Also, additional testing may be performed as shown by step575. At any time, the operator or internal logic may decide to abort the cycle and terminate the test. All the packer elements are preferably retracted (deflated) instep580 and the testing tool is free to move in the wellbore. Other methods thanmethod500 may also benefit from sealed interval of adjustable length. These methods include, but are not limited to, injecting materials into the formation, or formation testing to determine for example pressure and mobility of hydrocarbons in a reservoir. As mentioned above, a local interference test (also known as interval pressure transient test of IPTT) may benefit from sealed interval of adjustable length. The pressure in sealed intervals of variable length may be pulsed. The pressure pulse may be detected at a probe located above or below the sealed interval (similar to probe16cinFIG. 1C), that is in pressure communication with the formation.
• FIGS. 8A-8D show another illustration of a method for testing a subterranean formation according to one aspect of this invention.FIGS. 8A-8D show a portion of a testing tool similar totesting tool10 ofFIG. 2, lowered in awellbore11 traversing aformation12, as taught by step510 ofmethod500.Testing tool10 comprisespacker elements702,703,704 and705, and ports752,753,754 and755. In the example ofFIGS. 8A-8D,packer elements703 is slidable, for example using the apparatus described in more details with respect toFIG. 4.
• As a way of example, the length of the wellbore interval to be sealed determined in step515 ofmethod500 may be represented byinterval770 onFIGS. 8A-8D. As taught by step550 ofmethod500, the testing interval length may then be selected by slidingpacker element703 as indicated byarrow730 onFIG. 8A. The movement of packer element may be controlled by a downhole controller (not shown), either automatically according to instructions executed by the downhole controller, or under the supervision of a surface operator sending a command to the testing tool. The command sent to the testing tool could comprise a value of the testing interval length determined by the operator, for example in view of information recorded by downhole sensors (not shown) and sent uphole by a telemetry system (not shown).
• FIG. 8B illustrate a first testing operation. In the example ofFIG. 8B,packer elements702 and703 have been extended into sealing engagement with the wellbore wall15 (step555 of method500) and thetesting interval770 is isolated (step560 of method500). The testing operation (step565 of method500) may comprise the optional step of perforating the formation as shown by tunnel722 information12. Perforation may be achieved by perforating guns, such as perforatinggun231 ofFIG. 3, or by any other method known by those skilled in the art. Note that the perforation of theformation12 about thetesting interval770 may be performed before or after inflation of thepacker elements702 and703. The testing operation shown in the example ofFIG. 8B comprises injecting material through the port752, for example steam, hot water, acid or solvent, into thetesting interval770 and theformation12. Injection of steam, hot water or solvent may be desirable for example to lower viscosity of heavy hydrocarbon information12 prior to sampling. Injection may also be desirable for testing the compatibility of the injected fluid with the formation or reservoir fluid. The injected material may be conveyed downhole in a cavity (not shown), similar to cavity150-1 inFIG. 2, or may also be conveyed from the surface into the conveyance mean13b,as explained above with respect toFIG. 1B. The testing operation preferably allows for the injected material to diffuse in theformation12, as indicated by arrows731. During this soaking period, various sensors (not shown) may measure formation of fluid properties, such as fluid temperature, fluid pressure, or formation resistivity profile along the radial, axial or azimuthal direction of the wellbore.
• FIGS. 8C and 8D illustrate an optional testing operation following the injection described inFIG. 8B. The length of a second testing interval can be selected, for example from the set of the distance betweenpacker element703 and704, the distance betweenpacker703 and705 or the distance betweenpacker704 and705. In the example ofFIG. 8C, a second testing interval771 betweenpacker elements705 and703 is sealed, as taught bystep570 ofmethod500. Alternatively,packer element704 may have been enabled instead of packer element705, sealing thereby a second testing interval with a shorter length. The testing tool may start drawing fluid from interval771 may be replaced bysand763, produced by an unconsolidated formation, and formation fluid762, as indicated byarrows732. Note that in the example ofFIG. 8C, it is assumed that the density of the formation fluid762, for example heavy oil, is larger than the density of the wellbore fluid761, for example water. Note also that formation fluid762 may be contaminated by injection materials or other materials.
• FIG. 8D shows the continuation of the sampling process started inFIG. 8C. InFIG. 8D, an alternate fluid communication with the testing tool is established through port754 by selectively opening a valve (not shown) associated with port754, for example a valve similar to valve243bofFIG. 3, and by closing a valve (not shown) associated with port753, for example a valve similar tovalve243aofFIG. 3. This operation may be initiated by a surface operator, for example in view of fluid properties measured by the testing tool, for example by a sensor similar to sensor131 ofFIG. 2, and send uphole via telemetry. This operation may alternatively be initiated by a downhole controller. Thus, formation fluid762 may enter the testing tool through port754, indicated byarrows733. In the example ofFIG. 8D,packer element704 has not been inflated, increasing thereby the risk of particles, such as sand or other debris, to enter the testing tool via port754. In some cases, there may still be particles in suspension in formation fluid754. It may be advantageous to pulverize these particles with particle breaking devices, such asparticles breaking devices160,161 or162 onFIG. 2. Formation fluid may then be analyzed by one or more sensor in the testing tool and/or captured in a cavity in the testing tool and brought to the surface for further analysis, as known by those skilled in the art.
• In the example ofFIG. 8C, the second testing interval771 is located below the first interval, for example to take advantage of gravity during a sampling operation of a heavy hydrocarbon information12. It will be appreciated by those skilled in the art that a second testing interval may have alternatively be chosen above the first interval, for example by extending initiallypacker elements704 and705 for sealing the first testing interval. Alternatively, the second testing interval may comprise the first testing interval, for example by extendingpacker element704 and retractingpacker element703.
• Although the present invention and its advantages have been described in detail, it should b understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims (29)

1. A method for testing a subterranean formation penetrated by a wellbore, the method comprising:

positioning the testing tool in the wellbore, the testing tool comprising a tool body, a plurality of packer elements spaced apart from one another along the longitudinal axis of the tool body, and at least one port on the tool body located between two of the plurality of packer elements;

selecting in situ the length of an interval of the wellbore to be sealed;

extending at least two packer elements into sealing engagement with the wellbore wall;

sealing the interval of the wellbore with the two packer elements; and

flowing fluid between the sealed interval and the testing tool through the port.

2. The method ofclaim 1 wherein selecting in situ the length of an interval on the wellbore wall to be sealed comprises sliding a packer element along the longitudinal axis of the tool body.

3. The method ofclaim 1 wherein

the downhole tool further comprises at least three packer elements; and

selecting in situ the length of an interval on the wellbore wall to be scaled comprises selectively enabling the extension of a first and a second packer elements.

4. The method ofclaim 1 wherein

the downhole tool further comprises a plurality of ports associated to a plurality of valves; and

the method further comprises selectively opening a valve to establish the fluid communication through the port associated with this valve.

5. The method ofclaim 3 further comprising extending a third packer element into sealing engagement with the wellbore wall.

6. The method ofclaim 5 wherein the third packer element is located between the first and second packer elements.

7. The method ofclaim 6 wherein

the downhole tool further comprises a plurality of ports associated to a plurality of valves; and

the method further comprises selectively opening a valve to establish the fluid communication through the port associated with this valve.

8. The method ofclaim 1 wherein the selecting in situ the length of an interval on the wellbore wall to be sealed is based on the value of a measured property by a downhole tool.

9. The method ofclaim 1 further comprising pulverizing particles carried by the fluid flowed through the port.

10. A method for testing a subterranean formation penetrated by a wellbore, the method comprising:

positioning a testing tool in the wellbore, the testing tool comprising a tool body, a plurality of packer elements spaced apart from one another along the longitudinal axis of the tool body, and at least one port on the tool body located between two of the plurality of packer elements;

extending at least two packer elements into sealing engagement with the wellbore wall;

sealing a first interval of the wellbore;

flowing fluid between the first sealed interval and the testing tool through the port;

extending a third packer element into sealing engagement with the wellbore wall; and

sealing a second interval of the wellbore.

11. The method ofclaim 10 further comprising flowing fluid from the second sealed interval into the testing tool through the port.

12. The method ofclaim 10 wherein the second interval being comprised in the first interval.

13. The method ofclaim 10 wherein

the downhole tool further comprises a plurality of ports;

the method further comprises flowing fluid from the second sealed interval into the testing tool through another port.

14. The method ofclaim 10 wherein

the downhole tool further comprises a cavity in fluid communication with the port on tool body, the cavity carrying a material; and

flowing fluid between the first sealed interval and the testing tool through the port comprises releasing the material in the wellbore.

15. The method ofclaim 10 wherein

the downhole tool further comprises a cavity in fluid communication with the port on tool body; and

flowing fluid between the first sealed interval and the testing tool through the port comprises drawing fluid into the cavity.

16. The method ofclaim 10 wherein

the downhole tool further comprises a sensor; and

the method further comprises monitoring a property with the sensor.

17. The method ofclaim 16 further wherein extending another packer element into sealing engagement with the wellbore wall is triggered by the monitored property.

18. The method ofclaim 10 further comprising pulverizing particles carried by the fluid flowed through the port.

19. A method for testing a subterranean formation penetrated by a wellbore, the method comprising:

adjusting a port on a testing tool, the testing tool comprising a tool body, a plurality of packer elements spaced apart from one another along the longitudinal axis of the tool body, and at least a port on the tool body located between two of the plurality of packer elements;

positioning the testing tool in the wellbore;

extending at least two packer elements into sealing engagement with the wellbore wall;

sealing an interval of the wellbore; and

draining fluid from the sealed interval into the testing tool through the adjusted port.

20. The method ofclaim 19 wherein

the testing tool further comprises a screen filter; and

the method further comprises adjusting a characteristic of the screen filter.

21. The method ofclaim 19 further comprising reducing the fluid volume trapped in the sealed interval by selecting the outer diameter of the snorkel assembly.

22. The method ofclaim 19 wherein adjusting a port comprises adjusting the location of the port within a packer interval.

23. The method ofclaim 19 wherein adjusting a port on a testing tool comprises adapting a snorkel assembly on the testing tool, the snorkel assembly comprising a snorkel port and a fluid communication between the port on the tool body and the snorkel port, the snorkel port and the tool port being substantially offset from each other.

24. A system for testing a subterranean formation penetrated by a wellbore, the system comprising:

a testing tool comprising a tool body, a plurality of packer elements spaced apart from one another along the longitudinal axis of the tool body, and at least a port on the tool body located between two packer elements; and

a snorkel assembly adaptable on the testing tool comprising a snorkel port and a fluid communication between the port on the tool body and the snorkel port, the snorkel port and the tool port being substantially offset from each other.

25. The system ofclaim 24 further comprising a screen filter.

26. The system ofclaim 24 wherein the snorkel port is located at a different level with respect to the longitudinal axis of the tool body than the port on the tool body.

27. The system ofclaim 24 wherein the snorkel port extends around the circumference of the tool.

28. The system ofclaim 24 further comprising:

a flow line in the testing tool, the flow line being in fluid communication with the port on the tool; and

an ultrasonic transmitter for emitting a wave in the flow line.

29. The system ofclaim 24 further comprising:

a flow line in the testing tool, the flow line being in fluid communication with the port on the tool; and

a laser diode for emitting a wave in the flow line.

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