The preheating device and method of heavy crude reservoirTechnical field
The present invention relates to Development of Viscous Crude Oil technical field, in particular to the preheating device and method of a kind of heavy crude reservoir.
Background technique
Steam assisted gravity drainage (SAGD) is to develop the effective technology means of heavy crude reservoir, in stratum initial conditionUnder not no fluid ability high viscosity oil, oil reservoir warm-up phase need to be undergone, the thermal communication between injection-production well is realized, be fully warmed-upOil reservoir is the premise for realizing gravity drainage.Firstly, the concept of steam assisted gravity drainage and preheating is introduced it is as follows, so as toUnderstand the present invention:
SAGD: it is steamed after being continuously injected into steam and forming vapor chamber using the horizontal well or vertical well arranged in oil reservoirCrude oil around vapour chamber is reduced by thermoviscosity, because of the gravity being subject to, flow to the horizontal production well of oil reservoir bottom sectionNear, then it is produced to ground.
Preheating: in order to enable the vapor chamber of SAGD uniformly to develop, in SAGD startup stage, into horizontal well, tripping in is long connectsContinuous oil pipe, is continuously injected into steam to long oil pipe with lower steam injection rate, steam is flowed into casing from horizontal well toe-end, with setPipe condensation by contact discharges heat, heats neighbouring stratum.Condensed water is in casing by output.Whole process needs to keep steam notThe phenomenon that causing non-uniform heat flux into stratum.Circulation preheating stablizes effective heat even until being formed between injection well and horizontal wellLogical position, it can start the SAGD stage.
Two kinds of modes preheated are generally taken to establish dual horizontal well combination S AGD note, adopting the thermal communication between well, that is, are steamedVapour handle up preheating and steam circulation preheating.Existing two kinds of pre-heating means are introduced below as follows:
One, circulation preheating refers to that wherein steam soak preheating is upper and lower horizontal well while carrying out steam soak exploitation high temperature,Purpose is to reduce strata pressure, establishes thermal communication, and warm-up phase of handling up can finally make horizontal well interwell communication temperature reach 80 DEG C,Pressure drops to 3MPa or so, and stage recovery percent of reserves can reach 21%.But steam soak preheating cannot be evenly heated horizontal segment,With the increase for round of handling up, for thermal field in sexual development is inherited, non-homogeneous degree is more serious, so, it fully relies on high pressure and handles upProduction obtains thermal communication purpose to reach, and often will cause horizontal segment heating unevenly, can restrict and produce after being transferred to SAGD exploitationEffect reduces ultimate recovery.
Two, steam heated oil reservoir in the case where not entering oil reservoir (or minute quantity enters oil reservoir), steam is only in horizontal wellInterior one circle of circulation, therefore claim circulation preheating.The steam circulation of (2-4 months) enough for a long time is theoretically carried out in injection-production wellAfterwards, thermal communication can be established between injection-production well, and horizontal segment can be evenly heated.But only in shallow layer thick oil oil in practical applicationHiding realizes the circulation preheating of steam, for mid-deep strata heavy crude reservoir (600-1000m), since reservoir pressure is higher compared with shallow-layer,It is depressurized to 3-4MPa in steam soak even if having developed oil reservoir, in mid-deep strata heavy crude reservoir, high-temperature-hot-water is difficult to also realize and follow certainlyRing, that is, the circulation preheating of mid-deep strata heavy crude reservoir are difficult to realize, and limit the SAGD exploitation of mid-deep strata heavy crude reservoir.
By it is above-mentioned it is found that it is existing using steam assisted gravity drainage (SAGD) technological development heavy crude reservoir when, to viscous crudeThe method of oil reservoir preheating, preheating is uneven, preheats low efficiency, complicated for operation, and the circulation preheating of mid-deep strata heavy crude reservoir is difficult to realityExisting, application range is limited.
Summary of the invention
The embodiment of the invention provides a kind of preheating device of heavy crude reservoir, the preheating to improve heavy crude reservoir is uniformProperty, the pre- thermal efficiency reduces warm-up operation cost and complexity, expands the application range of preheating, which includes:
Upper horizontal injection well and lower horizontal production well, are arranged in the destination layer position of heavy crude reservoir to be preheated；Upper horizontal injectionWell includes: upper horizontal injection well vertical section and the upper horizontal injection well horizontal segment that is connected with upper horizontal injection well vertical section；It is lauchedFlat producing well includes: that lower horizontal production well vertical section and the production well water all one's life that is lauched being connected with lower horizontal production well vertical section are put downSection；
Upper horizontal injection well injection pipe is arranged in upper horizontal injection well vertical section, horizontal for upward horizontal injection wellNano-fluid is injected in section；Upper horizontal injection well electric heating column is arranged in upper horizontal injection well horizontal segment, for injectionNano-fluid is electrically heated；
Lower horizontal production well injection pipe is arranged in lower horizontal production well vertical section, horizontal for downward horizontal producing wellNano-fluid is injected in section；Lower horizontal production well electric heating column, setting is being lauched in production well horizontal segment all one's life, for injectionNano-fluid is electrically heated；
The preheating device of the heavy crude reservoir passes through the effect of electricity by nano-fluid, in the case where not undergoing phase transition,The thermal energy persistently converted electrical energy into is conducted to oil reservoir, does not need to produce during preheating, after preheating finishes, the production phase will be receivedMeter Liu Ti is produced with reservoir fluid, or is not produced, as the medium for accelerating oil reservoir heat transfer.
The embodiment of the invention also provides a kind of pre-heating mean of heavy crude reservoir, the preheating to improve heavy crude reservoir is uniformProperty, the pre- thermal efficiency reduces warm-up operation cost and complexity, expands the application range of preheating, this method comprises:
In the destination layer position of heavy crude reservoir to be preheated, upper horizontal injection well and lower horizontal production well are set；
It upward horizontal injection well horizontal segment and is lauched to produce all one's life and injects nano-fluid in well horizontal segment；
The nano-fluid of injection is electrically heated；
The pre-heating mean of the heavy crude reservoir passes through the effect of electricity by nano-fluid, in the case where not undergoing phase transition,The thermal energy persistently converted electrical energy into is conducted to oil reservoir, does not need to produce during preheating, after preheating finishes, the production phase will be receivedMeter Liu Ti is produced with reservoir fluid, or is not produced, as the medium for accelerating oil reservoir heat transfer.
The circulation preheating traditional relative to heavy crude reservoir and preheating method of handling up, technical solution provided by the invention will be electricDuring heating and nano-fluid householder method are introduced to heavy crude reservoir preheating, electric heating, effect fast with heating speed are utilizedThe advantages of rate is high, easily controllable, efficiency of heating- utilization height and stable operation, and the nano-fluid to inject pit shaft is carrier, toHeat is transmitted on stratum, and nano-fluid has the characteristics that the fast thermal conductive property of diffusion velocity is strong, improves reservoir fluid mobility, reducesTraditional pre-heating mean, along journey heat loss, and reduces the output of reservoir fluid to shaft bottom injection steam, it is easier to keep oilPressure balance in hiding.For steam circulation preheating, this method can reduce 30% or more heat loss, shorten preheating time40% or more.And traditional circulation preheating method is overcome in preheating low efficiency, the disadvantage of control method complexity etc..And it is wholeA warm avoids the production of steam and heat there is no injecting hot steam and condensed fluid being given rise to the process on groundOut, heat loss rate is reduced；To achieve the purpose that uniformly effectively high speed forms thermal communication.
Therefore, by above-mentioned it is found that technical solution provided by the invention combines the preheating of horizontal well nano-fluid and electricity addsThe double dominant of hot pre-heating mean makes even heat be transmitted to the region between two mouthfuls of water horizontal wells needed to heat, has reached uniformThe purpose of preheating improves the pre- thermal efficiency and producing degree of reservoir, reduces warm-up operation cost and complexity, expands answering for preheatingWith range, the final recovery ratio for improving viscous crude.
Detailed description of the invention
The drawings described herein are used to provide a further understanding of the present invention, constitutes part of this application, notConstitute limitation of the invention.In the accompanying drawings:
Fig. 1 is the structural schematic diagram of the preheating device of heavy crude reservoir in the embodiment of the present invention；
Fig. 2 is the flow diagram of the pre-heating mean of heavy crude reservoir in the embodiment of the present invention.
Specific embodiment
To make the objectives, technical solutions, and advantages of the present invention clearer, right below with reference to embodiment and attached drawingThe present invention is described in further details.Here, exemplary embodiment and its explanation of the invention is used to explain the present invention, but simultaneouslyIt is not as a limitation of the invention.
This method belongs to oil extraction in oil field technical field, in particular to a kind of novel dual horizontal well nano-fluid auxiliary electrical heaterPipeline start up by preheating SAGD method, has the pre- thermal efficiency of well of improving the standard, and a section development degree of improving the standard reduces the operation of SAGD preheatingThe advantages that cost.It is specifically described below.
Fig. 1 is the structural schematic diagram of the preheating device of heavy crude reservoir in the embodiment of the present invention, as shown in Figure 1, the device, packetIt includes:
Upper horizontal injection well 1 and lower horizontal production well 2, are arranged in the destination layer position of heavy crude reservoir to be preheated；The upper waterFlat injection well 1 includes: upper horizontal injection well vertical section 17 and the upper horizontal note being connected with the upper horizontal injection well vertical section 17Enter well horizontal segment 18；The lower horizontal production well 2 includes: lower horizontal production well vertical section 27 and erects with the lower horizontal production wellWhat straight section 27 was connected is lauched production well horizontal segment 28 all one's life；
Upper horizontal injection well injection pipe 11 is arranged in the upper horizontal injection well vertical section 17, for horizontal note upwardsEnter and injects nano-fluid in well horizontal segment 18；Upper horizontal injection well electric heating column 14, setting are horizontal in the upper horizontal injection wellIn section 18, for being electrically heated to the nano-fluid of injection；
Lower horizontal production well injection pipe 21 is arranged in the lower horizontal production well vertical section 27, raw for downward horizontalIt produces and injects nano-fluid in well horizontal segment 28；Lower horizontal production well electric heating column 24, setting are put down in the production well water all one's life that is lauchedIn section 28, for being electrically heated to the nano-fluid of injection.
The circulation preheating traditional relative to heavy crude reservoir and preheating method of handling up, technical solution provided by the invention will be electricDuring heating and nano-fluid householder method are introduced to heavy crude reservoir preheating, using upper horizontal injection well electric heating column underHorizontal production well electric heating column is electrically heated, and has heating speed fast, high-efficient, easily controllable, and efficiency of heating- utilization is high and graspsMake stable advantage, and the nano-fluid to inject pit shaft transmits heat to stratum, nano-fluid has diffusion speed as carrierThe strong feature of fast thermal conductive property is spent, reservoir fluid mobility is improved, reduces traditional pre-heating mean to shaft bottom injection steamAlong journey heat loss, and reduce the output of reservoir fluid, it is easier to keep pressure balance in oil reservoir.It is preheated relative to steam circulationFor, this method can reduce 30% or more heat loss, shorten for 40% or more preheating time.And it is pre- to overcome traditional circulationHot mode is in preheating low efficiency, the disadvantage of control method complexity etc..And entirely warm is not present injection hot steam and willCondensed fluid gives rise to the process on ground, avoids the output of steam and heat, reduces heat loss rate；To reach uniformly effectivelyHigh speed forms the purpose of thermal communication.
In addition, nano-fluid about injection moves towards problem, it is explained in detail: due to traditional circulation preheating methodIt is to inject steam into annular space between oil pipe and casing, the stratum between two mouthfuls of water horizontal wells is heated by heat exchange, steam is completeIt just needs to inject new steam after condensation, and the hydromining of condensation is come out, to keep continuous heating.And the embodiment of the present invention relies onNano-fluid, can be in the case where not undergoing phase transition by the effect of electricity, and the thermal energy persistently converted electrical energy into is conducted to oil reservoir,So not needing to produce during preheating.After preheating finishes, the production phase can be produced nano-fluid with reservoir fluid,It can not also produce, as the medium for accelerating oil reservoir heat transfer.
Therefore, by above-mentioned it is found that technical solution provided by the invention combines the preheating of horizontal well nano-fluid and electricity addsThe double dominant of hot pre-heating mean makes even heat be transmitted to the region between two mouthfuls of water horizontal wells needed to heat, has reached uniformThe purpose of preheating improves the pre- thermal efficiency and producing degree of reservoir, reduces warm-up operation cost and complexity, expands answering for preheatingWith range, the final recovery ratio for improving viscous crude.
When it is implemented, as shown in Figure 1, upper horizontal injection well injection pipe 11 is lower deep to upper horizontal injection well horizontal segment 18Inlet, upper horizontal injection well electric heating column 14 are lowered into the end of horizontal injection well horizontal segment 18, i.e., upper horizontal injectionWell electric heating column 14 guarantees the uniform preheating to upper horizontal injection well horizontal segment through entirely upper horizontal injection well horizontal segment 18.The setting of lower horizontal production well injection pipe 21 and lower horizontal production well electric heating column 24 is with above-mentioned, and details are not described herein.
When it is implemented, the length of above-mentioned horizontal injection well electric heating column and lower horizontal production well electric heating column is greater than 300Rice, power are greater than 100Kw, enclosure coater magnesium oxide insulated layer.
When it is implemented, before being preheated, firstly, qualified oil reservoir (above-mentioned heavy crude reservoir to be preheated) is selected, it is describedThe geologic parameter of qualified oil reservoir meets the following conditions: reservoir buried depth 100-1000m, and continuous core intersection is more than or equal to 10m, containsOily saturation degree is greater than 0.6, and porosity is greater than 20%, and vertical permeability and horizontal permeability ratio are greater than 0.3, and viscosity of crude is greater than2000mPa.s.In addition, the oil reservoir meets the following conditions: existing without edge-bottom water, oil reservoir interval interbed distribution is discontinuous.
When it is implemented, then, dual horizontal well (including above-mentioned upper horizontal injection well 1 is affixed one's name in the middle part of the qualified oil reservoirWith lower horizontal production well 2), the dual horizontal well include: the upper horizontal well (upper horizontal injection well 1) that vertical well spacing is 4-6m and underHorizontal well (lower horizontal production well 2), the well depth of dual horizontal well is less than 1000 meters, and the horizontal section length of double levels is in 300m or more.
When it is implemented, the dual horizontal well can also meet the following conditions: the complete well of dual horizontal well cutting seam sieve tube, seam long 10~30m, slit width 3mm stitch 5~10m of spacing, 5~10 ° of phase difference between seam, wherein upper horizontal well (mentions in embodiments of the present inventionTo upper horizontal well be are as follows: upper horizontal injection well 1) the complete well of slot in 90 range of upside, lower horizontal well is (in the embodiment of the present inventionIn the lower horizontal well mentioned be: lower horizontal production well 2) the complete well of slot within the scope of 90 ° of downside.
When it is implemented, the tripping in temperature and pressure sensor in upper horizontal well and lower horizontal well, continuously monitors two wellsTemperature and pressure variation in cylinder.The specific implementation details of temperature and pressure sensor are as follows:
In one embodiment, the preheating device of heavy crude reservoir further include:
First temperature sensor 15 is arranged in upper horizontal injection well horizontal segment 18, for monitoring upper horizontal injection well waterTemperature in flat section 18；
Second temperature sensor 25, setting are being lauched in production well horizontal segment 28 all one's life, produce well water all one's life for monitoring to be lauchedTemperature in flat section 28；
The temperature that the upper horizontal injection well electric heating column 14 is monitored according to first temperature sensor 15, heating noteThe nano-fluid entered, the temperature that the lower horizontal production well electric heating column 24 is monitored according to the second temperature sensor 25,The nano-fluid for heating injection, until upper horizontal injection well 1 and lower horizontal production well 2 realize thermal communication.
When it is implemented, optical fiber continuous temperature measurement can be used in the first temperature sensor 15 and second temperature sensor 25.
In one embodiment, the preheating device of heavy crude reservoir further include:
First pressure sensor 16 is arranged in upper horizontal injection well horizontal segment 18, for monitoring upper horizontal injection well waterPressure in flat section 18；
Second pressure sensor 26, setting are being lauched in production well horizontal segment 28 all one's life, produce well water all one's life for monitoring to be lauchedPressure in flat section 28；
The pressure that the upper horizontal injection well injection pipe 11 is monitored according to the first pressure sensor 16, it is horizontal upwardsNano-fluid is injected in injection well horizontal segment 18, the lower horizontal production well injection pipe 21 is according to the second pressure sensor 26The pressure monitored injects nano-fluid in downward horizontal producing well horizontal segment 28, in holdings horizontal injection well 1 be lauched all one's lifePressure is in the first preset range value in production well 2.
When it is implemented, can uniformly dispose 4~5 first pressure sensors in upper horizontal injection well horizontal segment 1816, similarly, 4~5 second pressure sensors 26 can be uniformly disposed being lauched to produce in well horizontal segment 28 all one's life.
When it is implemented, should be mended at any time according to the monitoring result of first pressure sensor 16 and second pressure sensor 26Nano-fluid is filled, to keep upper horizontal injection well horizontal segment 18 and be lauched the pressure and heavy crude reservoir that are produced in well horizontal segment 28 all one's lifePressure is consistent or a little higher than heavy crude reservoir pressure, and it is 1t/d that nano-fluid, which supplements speed,.Above-mentioned first preset range value can be withIt is configured according to practical work experience and operating condition.
When it is implemented, when the nanometer of upper horizontal injection well electric heating column and the heating injection of lower horizontal production well electric heating columnFluid continuously preheats upper horizontal well and lower horizontal well simultaneously, observes pit shaft pressure and temperature at any time, kept in pit shaftWith certain liquid and certain pressure.
Based on the same inventive concept, a kind of pre-heating mean of heavy crude reservoir is additionally provided in the embodiment of the present invention, it is such as followingEmbodiment described in.It is thick since the principle of the pre-heating mean problem of heavy crude reservoir is similar to the preheating device of heavy crude reservoirThe implementation of the pre-heating mean of oil reservoir may refer to the implementation of the preheating device of heavy crude reservoir, and overlaps will not be repeated.BelowUsed, the combination of the software and/or hardware of predetermined function may be implemented in term " unit " or " module ".Although following realApply device described in example and preferably realized with software, but the combined realization of hardware or software and hardware be also canIt can and be contemplated.
Fig. 2 is the flow diagram of the pre-heating mean of heavy crude reservoir in the embodiment of the present invention, as shown in Fig. 2, this method packetInclude following steps:
Step 101: in the destination layer position of heavy crude reservoir to be preheated, upper horizontal injection well and lower horizontal production well are set；
Step 102: upward horizontal injection well horizontal segment and being lauched to produce all one's life and inject nano-fluid in well horizontal segment；
Step 103: the nano-fluid of injection is electrically heated.
In one embodiment, the pre-heating mean of heavy crude reservoir further include:
Horizontal injection well horizontal segment and the temperature being lauched in production well horizontal segment all one's life in monitoring；
According to the temperature monitored, the nano-fluid of injection is heated, until upper horizontal injection well and lower horizontal production well are realExisting thermal communication.
In one embodiment, the pre-heating mean of heavy crude reservoir further include:
Horizontal injection well horizontal segment and the pressure being lauched in production well horizontal segment all one's life in monitoring；
According to the pressure monitored, upward horizontal injection well horizontal segment and be lauched all one's life produce well horizontal segment in inject nanometer streamBody horizontal injection well and is lauched and produces borehole pressure all one's life in the first preset range value in holding.
In one embodiment, the pre-heating mean of heavy crude reservoir further include:
After a preset time lapses, in raising horizontal injection well operating pressure, be higher than the pressure of horizontal injection wellLower horizontal production well preset pressure.
Specifically, it can be after nano-fluid auxiliary electrical heater preheating 1-2 months, upper horizontal well and lower horizontal wellboreTemperature has increased to a certain degree, improves the operating pressure of upper horizontal well at this time, makes to form pressure difference drive between two mouthfuls of water horizontal wellsFor relationship, such design can promote the thermal communication between two mouthfuls of wells.Preferably, in one embodiment of this invention, above-mentionedUpper horizontal well and lower horizontal well temperature should be increased to 100 DEG C or more, then apply pressure difference between 50kPa~500kPa.
When forming thermal communication between upper horizontal well and lower horizontal well, it is transferred to gravity drainage mode development, upper horizontal well is (i.e.Upper horizontal injection well) continuous steam injection, lower horizontal well (descending horizontal production well) continuous production.
In one embodiment, the pre-heating mean of heavy crude reservoir further include:
When monitoring that the reset pressure wait preheat heavy crude reservoir is greater than preset pressure value, to upper horizontal injection well and it is lauchedFlat producing well carries out steam soak exploitation, until the pressure of heavy crude reservoir to be preheated drops in the second pre-set pressure range value.
When it is implemented, the steam soak period is 3~5 rounds, and bottom pressure and reservoir pressure are observed at any timeVariation is reduced to 3.5MPa to bottom pressure and (utilizes hereinafter, the preheating of dual horizontal well nano-fluid auxiliary electrical heater can be transferred toPre-heating mean provided in an embodiment of the present invention preheats heavy crude reservoir).Second pre-set pressure range value can be 3.5MPaBelow.
When it is implemented, the diameter of nano particles value range of the nano-fluid in the embodiment of the present invention be 10nm~20nm, nanoparticle include: SiC, Al2O3, one of CuO, Ag and Au or any combination, base fluid include: water, pure and mild oil, receiveThe volume ratio value range of rice corpuscles and water is 0.~5%.
The present invention provides a kind of dual horizontal well nano-fluid auxiliary electrical heater pipeline start up by preheating SAGD method, mainly solves viscous crudeThe circulation warm-up operation of oil reservoir is complicated, the problem of using by limitation.In one embodiment, viscous crude provided in an embodiment of the present inventionThe pre-heating mean of oil reservoir, comprising the following steps:
Step 1: selecting qualified oil reservoir, the geologic parameter of the qualification oil reservoir meets the following conditions: reservoir buried depth 100-1000m, continuous core intersection are more than or equal to 10m, and oil saturation is greater than 0.6, and porosity is greater than 20%, vertical permeability and waterFlat permeability ratio is greater than 0.3, and viscosity of crude is greater than 2000mPa.s；
Step 2: dual horizontal well is affixed one's name in the middle part of the qualified oil reservoir, the dual horizontal well includes: that vertical well spacing is 4-6mUpper horizontal well and lower horizontal well, the well depth of dual horizontal well is less than 1000 meters, and the horizontal section length of double levels is in 300m or more；
Step 3: the tripping in temperature and pressure sensor in upper horizontal well and lower horizontal well continuously monitors in two pit shaftsTemperature and pressure variation；
Step 4: if oil reservoir reset pressure is greater than 5MPa, needing to upper horizontal well and lower horizontal well while carrying out steam and gulp downExploitation is spat, the qualified oil reservoir is made to be depressurized to 3.5MPa or less；
Step 5: and then horizontal well injection pipe and upper horizontal well electricity add in tripping in the upper horizontal well of the dual horizontal wellPlume, deeply to the inlet of upper horizontal well horizontal segment under upper horizontal well injection pipe, upper horizontal well electric heating column is lowered into horizontal wellAt the tiptoe of section；Horizontal well injection pipe and lower horizontal well electric heating column under tripping in the lower horizontal well of the dual horizontal well, underIt is arrived deeply under horizontal well electric heating column at the tiptoe of lower horizontal well horizontal segment；
Step 6: being then injected into proper amount of nano fluid and preheated, upper horizontal well and lower horizontal well carry out continuously adding simultaneouslyHeat observes pit shaft pressure and temperature at any time, keeps having certain liquid and certain pressure in pit shaft.
Further, mid-deep strata oil reservoir dual horizontal well nano-fluid auxiliary electrical heater pre-heating mean further include:
Step 7: after the preheating of nano-fluid auxiliary electrical heater 1-2 months, the temperature of upper horizontal well and lower horizontal wellbore isRisen to a certain extent, improve the operating pressure of upper horizontal well at this time, makes to form pressure difference displacement relationship between two mouthfuls of water horizontal wells,Promote the thermal communication between two mouthfuls of wells.
When forming thermal communication between upper horizontal well and lower horizontal well, it is transferred to gravity drainage mode development, upper horizontal well connectsContinuous steam injection, lower horizontal well continuous production.
In one embodiment of this invention, oil reservoir described in step 1) meets the following conditions: existing without edge-bottom water, oil reservoirInterval interbed distribution is discontinuous；
In one embodiment of this invention, dual horizontal well described in step 2) meets the following conditions: dual horizontal well slot sieveIt has managed well, has stitched long 10~30m, slit width 3mm, stitched 5~10m of spacing, 5~10 ° of phase difference between seam, wherein upper horizontal well is in upsideThe complete well of slot in 90 ranges, lower horizontal well complete well of slot within the scope of 90 ° of downside；
In one embodiment of this invention, temperature and pressure sensor described in step 3) meets the following conditions: temperature passesSensor uses optical fiber continuous temperature measurement, and 4~5 pressure sensors are uniformly disposed in pit shaft；
In one embodiment of this invention, steam soak period described in step 4) is 3~5 rounds, and is observed at any timeBottom pressure and reservoir pressure variation, preheating can be transferred to by being reduced to 3.5MPa or less to bottom pressure；
In one embodiment of this invention, steam soak period described in step 4) is 3~5 rounds, and is observed at any timeBottom pressure and reservoir pressure variation, dual horizontal well nano-fluid auxiliary can be transferred to by being reduced to 3.5MPa or less to bottom pressureElectric heating preheating；
In one embodiment of this invention, electric heating column described in step 5) should meet the following conditions: electric heating column lengthIt should be greater than 300m, power is greater than 100Kw, enclosure coater magnesium oxide insulated layer；
In one embodiment of this invention, nano-fluid described in step 6) should meet the following conditions: diameter of nano particlesIn 10nm~20nm, for the volume ratio of nanoparticle and water 0.~5%, nanoparticle can be SiC, Al2O3, CuO, Ag, Au etc.Type, base fluid can be water, alcohol, the substance of oil series；
In one embodiment of this invention, process described in step 6) should supplement nano-fluid at any time and keep in horizontal wellborePressure reservoir pressure consistent or a little higher than with reservoir pressure, it is 1t/d that fluid, which supplements speed,；
In one embodiment of this invention, upper horizontal well and lower horizontal well temperature described in step 7) should be increased to 100 DEG CMore than, then apply pressure difference between 50kPa~500kPa.
The dual horizontal well that the embodiment of the present invention is mentioned includes: upper horizontal injection well 1 and lower horizontal production well 2；Upper levelWell is upper horizontal injection well 1, and lower horizontal well is lower horizontal production well 2.
It is illustrated again with example below, in order to understanding how to implement the present invention.
Example one:
Xinjiang oil reservoir depth 200m, core intersection 10m, reservoir permeability 2000md, 18 DEG C of reservoir temperature；Reservoir temperatureLower crude oil deaeration viscosity 500000mPa.s, oil saturation 75%, 6 ° of oil reservoir inclination angle.Circulation preheating note adopts parameter: shaft bottom mass dryness fraction75%, steam maximum injection pressure 2.0MPa.Electric heater parameter: 250 DEG C of operation temperature, heating power 150KW.Nano-fluidParameter: SIC diameter of nano particles 13nm, volumetric concentration 1.5%.
1) it is screened according to characteristics of reservoirs, meets steam assisted gravity drainage screening criteria: oil reservoir depth < 1000m；OilThickness degree > 4m；Oil reservoir plane permeability > 500md, oil reservoir vertical permeability > 200md；Viscosity of crude > 2000mPa.s；Oil-containing is fullAnd degree > 50%；Net-gross ratio > 0.7；
2) horizontal injection well horizontal segment is designed as 200m, upper horizontal injection well horizontal segment with production well horizontal segment all one's life is lauched onAnd it is lauched and produces vertical distance 4m between well horizontal segment all one's life；
3) tripping in temperature-measuring optical fiber (temperature sensor) and pressure sensor in upper horizontal well and lower horizontal well, it is continuous to monitorTemperature and pressure variation in two pit shafts；
4) the then water in tripping in the upper horizontal injection well of dual horizontal well (upper horizontal injection well and lower horizontal production well)Flat injection well injection pipe and upper horizontal injection well electric heating column, deeply to upper horizontal well horizontal segment under upper horizontal injection well injection pipeInlet, upper horizontal well electric heating column are lowered at the tiptoe of horizontal injection well horizontal segment；In being lauched for the dual horizontal wellHorizontal production well injection pipe and lower horizontal production well electric heating column under tripping in flat producing well, under lower horizontal production well electric heating columnIt is deep to being lauched at the tiptoe of production well horizontal segment all one's life；
5) it is then injected separately into 2 tons of nano-fluids into two pit shafts to be preheated, to upper horizontal injection well and lower levelProducing well is continuously heated simultaneously, observes pit shaft pressure and temperature at any time, and is supplemented nano-fluid and kept well cylinder pressure2MPa。
6) laser heating 100 days, formation temperature has reached 120 DEG C between upper horizontal injection well and lower horizontal production well, turnsEnter SAGD exploitation.
Example two:
In practical oil reservoir application, steam circulation preheating and nano-fluid auxiliary electrical heater pipeline start up by preheating mode have been done respectivelyComparison.Oil reservoir basic parameter: porosity 30%, oil saturation 75%, permeability 2000md, core intersection 10m, reservoir temperatureLower crude oil deaeration viscosity 500000mPa.s.Circulation preheating note adopts parameter: shaft bottom mass dryness fraction 75%, steam maximum injection pressure4.0MPa.Electric heater parameter: 250 DEG C of operation temperature, heating power 200KW.Nano-fluid parameter: Al2O3 nanoparticle is straightDiameter 10nm, volumetric concentration 2%.
Well pattern basic parameter: horizontal section length 200m, upper and lower horizontal well spacing 5m.
It compared the effect and efficiency of two ways preheating:
1) regular circulation preheats 200 days, and ground layer for heating consumes steam 12000t, cost to 100 DEG C between horizontal well1440000 yuan；
2) nano-fluid auxiliary electrical heater preheats 200 days, and the stratum 5m near horizontal well is uniformly heated to 120 DEG C of left sidesThe right side, nearby maximum temperature reaches 150 degrees Celsius to horizontal well, consumes electricity 960000KWh, and 480000 yuan of cost.
In conclusion nano-fluid auxiliary electrical heater preheating method significantly improves the economy of warm, improveThe efficiency of preheating.
The technology of the present invention key point:
The present invention is a kind of nano-fluid auxiliary electrical heater pipeline start up by preheating SAGD technology, with conventional SAGD preheating method phaseNano-fluid high-termal conductivity and the high double dominant of the electrically heated thermal efficiency are made full use of than, the technology, therefore the present invention hasPreheating speed is fast, and heat utilization ratio is high, easy to operate, the more preferable feature of pre-heat effect.The embodiment of the present invention draws nano-fluidEnter to during SAGD pipeline start up by preheating, given full play to the advantage of the high thermal conductivity of nano-fluid, accelerate SAGD warm, improvesThe pre- thermal efficiency greatly improves the economy of warm in heavy crude reservoir SAGD exploitation.
The present invention provides a kind of new SAGD pipeline start up by preheating technologies to introduce electric heating and nano-fluid householder methodHigh using electrical heating method heating efficiency in SAGD warm, easily controllable and nano-fluid improves reservoir fluid mobility,The strong feature of the fast thermal conductive property of diffusion velocity transmits heat to stratum using the nano-fluid for injecting pit shaft as carrier；And it is entireWarm avoids the output of steam and heat there is no injecting hot steam and condensed fluid being given rise to the process on ground,Reduce heat loss rate；To achieve the purpose that uniformly effectively high speed forms thermal communication.
The invention belongs to field of oil development, in particular to a kind of novel dual horizontal well nano-fluid auxiliary electrical heater preheatingStart SAGD method, in conjunction with horizontal well nano-fluid preheating and electric heating pre-heating mean double dominant, make heat with transmittingTo the region for needing to heat between two mouthfuls of water horizontal wells to achieve the purpose that uniformly to preheat, to improve the pre- thermal efficiency and reservoir producing journeyDegree, the final recovery ratio for improving viscous crude.
In conclusion technical solution provided by the invention has the advantages that
1), preheating speed is fast, and Thermal Conductivity of Nanofluids used in method provided by the invention is higher than water by 40%, diffusionCoefficient ratio water is high by 20%, heat quickly can be imported into oil reservoir depths；
2), the thermal efficiency is high, and during conventional steam injected cycle preheating, mainly there are three part, surface lines for heat loss30% is accounted for, the wellbore heat loss on ground to shaft bottom accounts for 30%, and output hot-fluid body heat content accounts for 40%.The method that Ben Fanming is provided passes throughElectric heating generates heat inside oil reservoir, and heat is directly imported oil reservoir by the convection current of fluid, has avoided ground lineThe heat loss of line and pit shaft along journey, energy utilization efficiency height；Secondly hot fluid ground is not given rise into present invention application, instituteIt is completely maintained in inside oil reservoir with the heat that electric heating generates, really acts on heating oil reservoir；
3), easy to operate, compared with recycling preheating, heater need to be only fixed to shaft bottom by the present invention, and pass through a noteEntering pipe supplement nano-fluid reduces operation difficulty without disposing flow string and lifting equipment；
4), having a wide range of application, the present invention can be used for the heating measures of oil reservoir of the depth lower than 2000m, and in the present inventionCaused by the reservoir selection condition allows for the application depth of SAGD technology, conventional steam injection preheating needs to consider oil reservoir depthDegree and pressure, but method provided by the invention is due to the influence of not no heat loss, thus may be used in deeper oil reservoir.
The circulation preheating traditional relative to heavy crude reservoir and preheating method of handling up, the present invention have heating speed fast, heat benefitThe advantages of with high-efficient and stable operation, and reduce traditional pre-heating mean to shaft bottom injection steam along journey heat loss, andReduce the output of reservoir fluid, it is easier to keep pressure balance in oil reservoir.For steam circulation preheating, this method canTo reduce 30% or more heat loss, shortened for 40% or more preheating time.And it overcomes traditional circulation preheating method preheatingLow efficiency, the disadvantage of control method complexity etc..
The foregoing is only a preferred embodiment of the present invention, is not intended to restrict the invention, for the skill of this fieldFor art personnel, the embodiment of the present invention can have various modifications and variations.All within the spirits and principles of the present invention, madeAny modification, equivalent substitution, improvement and etc. should all be included in the protection scope of the present invention.