CN113984293A - Water leakage detection method of jacket of offshore platform - Google Patents

Abstract

The invention discloses a method for detecting water leakage of a jacket of an offshore platform, which comprises the following steps: scanning a part to be detected of the jacket by adopting gamma ray detection equipment according to a set plan, wherein the gamma ray detection equipment comprises an adjusting frame, a ray transmitting device and a ray receiving device, and when detecting, the part to be detected is positioned between the ray transmitting device and the ray receiving device; the method comprises the steps of measuring the thickness of marine organisms attached to the outer wall of a sea area conduit where a jacket is located in advance, calibrating the average absorption coefficients of dry marine organisms and wet marine organisms respectively according to a gamma ray matter absorption attenuation rule, calculating the thickness of seawater layers in the inner cavity of the conduit located below the sea surface and above the sea surface of a measured part according to the average absorption coefficients of the wet marine organisms and the dry marine organisms respectively, and finally determining the water inflow degree of the inner cavity of the measured part. The invention has the beneficial effects that: the method has high reliability of the detection result, and is convenient and quick.

Description

Offshore platform jacket water leakage detection method

Technical Field

The invention belongs to the technical field of offshore platform jacket detection, and particularly relates to a method for detecting water leakage of an offshore platform jacket.

Background

The offshore platform is a basic facility for offshore oil and gas resource production, the safety of the offshore platform is very important, and the jacket is a key point for ensuring the safety of the offshore platform as a supporting structure for bearing the whole platform. Except for the process water filling pipe, the jacket balances the weight of a part of the platform by virtue of buoyancy provided by a closed structure of the jacket, and provides powerful guarantee for stably positioning the ocean platform on the sea surface. However, the pipe is in a severe environment (especially in a splash zone), the operation condition is complex, the pipe bears a non-single load, and the pipe is required to bear the weight of the whole platform and also bear the influences of wind wave load, seismic wave and the like, so that various damages such as fatigue cracks, corrosion and the like inevitably occur in the service process of the pipe frame, seawater permeates into the pipe and even fills the inner cavity of the pipe, the pipe loses the function of providing buoyancy, and meanwhile, the invaded seawater can accelerate the corrosion of the pipe, and the structural safety of the pipe is seriously influenced. In addition, most of the platforms are in service for a long time, and some platforms are in service for a long time or even for an extended period, so that the offshore platform support conduit is subjected to regular water leakage detection, problems are found in time, and the offshore platform support conduit has important significance for guaranteeing continuous and safe production of the platforms.

The fmd (flowed member detection) device is the most effective and critical device for detecting water leakage from underwater conduits. Early devices for jacket water penetration testing were generally based on ultrasonic testing methods. It is reported (wushiwei et al, research and application of ocean platform deep water jacket structure rod piece detection method [ J ]. ocean engineering, 2009,21 (6)), that the ray water penetration rod piece detection method has the advantages of high detection efficiency and low cost compared with the ultrasonic water penetration rod piece detection method. However, although the basic principle of the rod water permeability detection method based on ray detection has been formed, a mature and easy-to-use detection method is still lacked. The offshore jacket is in a complex environment, and the accuracy of the ray detection method is also influenced. For example, in shallow sea areas, the jacket may be fixed to the sea floor and marine life attached to the jacket, with the marine life near the sea surface being below or above the surface of the jacket due to the tidal action affecting the water level. The underwater marine life is filled with water, the aquatic marine life is drained, and the gamma ray absorption coefficients of the dry marine life and the wet marine life are different, so that the accuracy of the measuring method is influenced, and the measuring result is probably completely unreliable. Currently, a reliable detection method with practical operation significance is still lacking.

Disclosure of Invention

In view of the above, the invention provides a water leakage detection method for a jacket of an offshore platform.

The technical scheme is as follows:

the method for detecting water leakage of the jacket of the offshore platform is characterized in that the detection process comprises the following steps:

scanning a part to be detected of the jacket by adopting gamma ray detection equipment, wherein the gamma ray detection equipment comprises an adjusting frame, a ray transmitting device and a ray receiving device, and during detection, positioning the part to be detected between the ray transmitting device and the ray receiving device and recording the initial intensity and the receiving intensity of gamma rays;

calibrating the absorption correlation coefficient of the marine organisms to the gamma rays in advance, measuring the thickness of the marine organisms of a part to be measured, measuring the thickness of a seawater layer between the ray transmitting device (200) and the ray receiving device (300) outside a conduit of the part to be measured, and measuring or inquiring to obtain the absorption correlation coefficient of the wall of the conduit to the gamma rays and the absorption correlation coefficient of seawater to the gamma rays;

and calculating to obtain the thickness of the seawater layer in the inner cavity of the to-be-measured part of the jacket according to the initial intensity, the receiving intensity, the thickness of the marine organism, the thickness of the seawater layer outside the to-be-measured part of the jacket and the absorption correlation coefficient of the marine organism, the jacket wall and the seawater on the gamma rays based on the material absorption attenuation rule of the gamma rays.

Preferably, the detection process is carried out as follows:

step one, scanning a to-be-detected part of a jacket by adopting gamma ray detection equipment according to a set plan;

wherein the radiation emitting device (200) emits an initial intensity of

And the gamma ray passes through the part to be detected, and the ray receiving device (300) receives and detects the intensity of the ray passing through the part to be detected

；

Step two, pre-measuring the thickness of marine organisms attached to the outer wall of the conduit of the sea area where the jacket is located

The thickness of the wet marine organisms attached to the outer wall of the vessel below the sea surface is recorded

The thickness of the dry marine organism attached to the outer wall of the conduit above the sea surface is

；

Simultaneously, according to the absorption and attenuation law of gamma ray substances, the average absorption coefficient of marine organisms is respectively calibrated

Wherein the average absorption coefficient of wet marine organisms is recorded as

The average absorption coefficient of the dry marine organisms is recorded as

；

Then carrying out the third step or the fourth step;

step three, calculating the thickness of the accumulated water in the inner cavity of the part to be measured immersed in the seawater by adopting the following formula

：

（Ⅰ），

In formula (I):

the thickness of a seawater layer which is positioned between a ray transmitting device (200) and a ray receiving device (300) of the testing device and outside the pipe wall of the part to be tested;

is the density of seawater;

the mass absorption coefficient of seawater to gamma rays;

2 times the jacket wall thickness;

is the jacket wall density;

is the mass absorption coefficient of the pipe wall of the jacket;

the density of accumulated water in the to-be-measured part of the jacket,

；

is the mass absorption coefficient of accumulated water in the part to be measured of the jacket,

；

wherein

Are all of the parameters which are known, and are,

is calculated according to the following formulaCalculating:

（Ⅱ）；

in formula (II): d is the distance between the ray transmitting device (200) and the ray receiving device (300),

the radial size of the outer wall of the guide pipe at the position to be measured;

step four, calculating the thickness of the accumulated water of the part to be measured exposed on the sea surface by adopting the following formula

：

（Ⅲ），

Step five, calculating in the step three or the step four

Or

The value of (D) and the inner diameter of the catheter at the position to be measured

And comparing to determine the water inlet degree of the inner cavity of the part to be detected.

Compared with the prior art, the invention has the beneficial effects that: the method comprehensively considers the influence of the environmental factors of the catheter on the gamma ray absorption, and solves the interference of the factors on the measurement through flexible pre-calibration treatment, so that the reliability of the detection result is high, and the measurement is convenient and quick.

Drawings

FIG. 1 is a schematic view of a test catheter according to the method of the present invention;

FIG. 2 is a schematic view of the detection principle;

FIG. 3 is a graph illustrating the calibration of the absorption coefficient of marine organisms;

FIG. 4 is a schematic diagram of a first perspective of the present invention;

FIG. 5 is a schematic diagram of a second perspective of the present invention;

FIG. 6 is a cross-sectional view taken along line A-A of FIG. 2;

FIG. 7 is an enlarged view of the portion m in FIG. 3;

FIG. 8 is a schematic structural view of a radiation emitting device;

FIG. 9 is a schematic view showing an internal structure of the radiation emitting apparatus;

FIG. 10 is a schematic structural diagram of a ray receiving device;

fig. 11 is a schematic view of the internal structure of the radiation receiving apparatus.

Detailed Description

The present invention will be further described with reference to the following examples and the accompanying drawings.

A method for detecting water leakage of a jacket of an offshore platform is based on a substance absorption attenuation rule of gamma rays. The intensity decay of gamma rays through matter can be represented by the following equation:

，

wherein:

the intensity of the gamma beam after passing through the measured substance;

is the initial intensity of the gamma beam;

is the thickness of the material through which the gamma beam passes;

density of the measured substance;

mass Absorption Coefficient (Mass Absorption Coefficient);

density of matter

And mass absorption coefficient

For knowing or measuring, on the basis of which the thickness of the substance is calculated by detecting the intensity of the radiation after it has passed through the substance to be measured

。

When gamma ray passes throughnThe intensity decay at each material layer can be further expressed as:

，

wherein

Is as followsnAbsorption correlation coefficient of individual substance layer.

Specifically, the detection method comprises the following steps:

step one, scanning a to-be-detected part of the jacket by adopting gamma ray detection equipment according to a set plan. Referring to fig. 1, in the present embodiment, the portion to be measured is a circular tube, and a connection line between theradiation emitting device 200 and theradiation receiving device 300 passes through the center of the circular tube, so that the gamma ray passes through the circular tube in the diameter direction.

The gamma ray detection device comprises an adjustingframe 100, aray emitting device 200 and aray receiving device 300;

during detection, the part to be detected is positioned between theray transmitting device 200 and theray receiving device 300;

wherein theray emitting device 200 emitsInitial strength of

And passes through the part to be measured, theray receiving device 300 receives and detects the intensity of the ray passing through the part to be measured

。

Step two, pre-measuring the thickness of marine organisms attached to the outer wall of the conduit of the sea area where the jacket is located

The thickness of the wet marine organisms attached to the outer wall of the vessel below the sea surface is recorded

The thickness of the dry marine organism attached to the outer wall of the conduit above the sea surface is

；

Simultaneously, according to the absorption and attenuation law of gamma ray substances, the average absorption coefficient of marine organisms is respectively calibrated

Wherein the average absorption coefficient of wet marine organisms is recorded as

The average absorption coefficient of the dry marine organisms is recorded as

；

And then carrying out the third step or the fourth step.

Step three, calculating the thickness of the accumulated water in the inner cavity of the part to be measured immersed in the seawater by adopting the following formula

：

（Ⅰ），

In formula (I):

the thickness of the seawater layer between theray transmitting device 200 and theray receiving device 300 of the testing device and outside the pipe wall of the part to be tested;

is the density of seawater;

the mass absorption coefficient of seawater to gamma rays;

2 times the jacket wall thickness;

is the jacket wall density;

is the mass absorption coefficient of the pipe wall of the jacket;

the density of accumulated water in the to-be-measured part of the jacket,

；

is the mass absorption coefficient of accumulated water in the part to be measured of the jacket,

；

wherein

Are all known parameters, as shown in figure 2,

calculated as follows:

（Ⅱ）；

where D is the distance between theradiation emitting device 200 and theradiation receiving device 300,

is the radial size of the outer wall of the guide pipe at the position to be measured.

Step four, calculating the thickness of the accumulated water of the part to be measured exposed on the sea surface by adopting the following formula

：

（Ⅲ）。

Step five, calculating in the step three or the step four

Or

The value of (D) and the inner diameter of the catheter at the position to be measured

Are compared to determineAnd determining the water inlet degree of the inner cavity of the part to be detected. Specifically, the water inlet degree of the inner cavity of the part to be detected is determined according to the following method:

computing

Or

And

the ratio of the values, and the water inflow percentage of the inner cavity of the part to be detected is judged according to the ratio of the values

D takes on the value of

Or

。

In the case of a vertically disposed conduit,

or

When the numerical value is 0, judging that the inner cavity of the part to be detected has no seawater;

or

Is equal to

And judging that the inner cavity of the part to be detected has seawater. For a conduit, detection is carried out at a plurality of point positions along the axial direction of the conduit, the seawater infiltration height in the conduit can be judged, and theoretically, the seawater infiltration height can be judged only by enough measured point positionsFind the interface of water inlet in the catheter cavity. If all the measurement points have seawater, the conduit can be considered to be full of water.

For horizontally or obliquely arranged catheters, calculating

Or

And

and judging the water inflow percentage of the inner cavity of the part to be detected according to the numerical ratio. For example, for a horizontally disposed catheter, when the numerical ratio is close to 30%, the water level in the catheter of a local segment of the measured part can be approximately considered to be 30% of the inner diameter of the lumen of the region. For the inclined conduit, the water inlet interface in the conduit cavity can be judged through detection of a plurality of points along the axial direction of the inclined conduit, so that the water inlet amount can be estimated.

The calibration method of the average absorption coefficient of the wet sea creatures and the dry sea creatures in the second step comprises the following steps:

and (3) taking a container, wherein the container can be made of a material with weak gamma ray absorption, so that the absorption of the container to the gamma ray can be ignored in the subsequent calibration process, and the calibration calculation process is simplified.

As shown in FIG. 3, a certain amount of marine life is filled into the container, the surface is kept flat, and the height of the marine life is recorded

Theray emitting device 200 and theray receiving device 300 are respectively close to the bottom surface of the container and the surface of the marine organism, and the ray intensity is detected

The average absorption coefficient of the dried marine organisms was calculated according to the following formula (IV)

，

（Ⅳ）；

Adding seawater with volume of Q into the container until the seawater just submerges the upper surface of the marine organism, and detecting the intensity of the rays again

The average absorption coefficient of wet marine organisms was calculated according to the following formula (V)

，

（Ⅴ）。

It should be noted that since the average density of marine organisms can also be measured by other methods, the average density can also be calculated by calibrating the absorption coefficient of marine organisms

And

then the average density and the average mass absorption coefficient are determined

Or

The calculation is carried out in place of formula (I) or formula (III). However, this calculation is inferior to the absorption coefficient obtained by calibration

And

the calculation is straightforward.

The specific structure of the detection device suitable for the detection method is as follows:

an offshore platform jacket water leakage detector comprises an adjustingframe 100, aray transmitting device 200 and aray receiving device 300. The adjustingframe 100 is an open frame with an opening, theray emitting device 200 and theray receiving device 300 are respectively arranged on the adjustingframe 100 on two sides of the opening, and theray emitting device 200 and theray receiving device 300 are arranged oppositely. The opening of the adjustingframe 100 is used for the detector to surround the catheter, so that theradiation emitting device 200 and theradiation receiving device 300 are respectively arranged on two sides of the catheter.

Theray emitting device 200 and theray receiving device 300 are respectively arranged on the adjustingframe 100 through a sliding positioning mechanism, and the sliding positioning mechanism is used for adjusting theray emitting device 200 and theray receiving device 300 to be close to or far away from the opening, so that the detector can adapt to catheters with different pipe diameters or positions. The adjustingframe 100 is provided with an adjusting device for adjusting theradiation emitting device 200 and theradiation receiving device 300 to be close to or far away from each other so as to adapt to catheters with different sizes.

As shown in fig. 4 and 5, the adjustingframe 100 includes amain body support 110 and two supportarms 120, the twosupport arms 120 are disposed opposite to each other in parallel, the same end of the twosupport arms 120 is connected to themain body support 110, and the other ends of the twosupport arms 120 extend to the same side of themain body support 110, so as to form the adjustingframe 100 with an opening on one side with themain body support 110. Themain body support 110 is provided with the adjusting device, and the adjusting device is connected with the twosupport arms 120. One of thesupport arms 120 is provided with theradiation emitting device 200 through one of the sliding positioning mechanisms, and theother support arm 120 is provided with theradiation receiving device 300 through the other of the sliding positioning mechanisms.

As shown in fig. 4 and 6, the adjusting means includes a sliding mechanism and atelescopic mechanism 130. One of the sliding mechanisms is disposed between each of thesupport arms 120 and themain body bracket 110, and the two sliding mechanisms guide the twosupport arms 120 to slide along a line connecting the ends of the two support arms. Thetelescopic mechanism 130 is connected between the sliding portions of the two sliding mechanisms.

Specifically, the sliding mechanism includes a slidinggroove 111 and a slidingblock 112 adapted to the slidinggroove 111. Themain body support 110 is provided with the slidinggroove 111, the slidinggroove 111 extends along a connecting direction of connecting ends of the twosupport arms 120, two slidingblocks 112 are arranged in the slidinggroove 111, and each slidingblock 112 is fixedly connected with the corresponding connecting end of thesupport arm 120.

In one embodiment, thebody bracket 110 includes a C-shaped steel, an inner cavity of the C-shaped steel is in a shape of a reduced groove, the inner cavity of the C-shaped steel forms the slidinggroove 111, and endstoppers 113 are respectively disposed at two ends of the C-shaped steel. The slidingblock 112 is arranged in the slidinggroove 111, a supportingarm connecting rod 114 is fixedly arranged on the slidingblock 112, one end of the supportingarm connecting rod 114 is fixedly connected with the slidingblock 112, the other end of the supporting arm connecting rod extends outwards from the notch of the slidinggroove 111, and the connecting end of the supportingarm 120 is sleeved on the supportingarm connecting rod 114 and is connected with the supporting arm connecting rod through a bolt. Because the outer wall of theslider 112 is fitted to the corresponding groove wall and groove bottom of the slidinggroove 111, and the notch of the C-shaped steel is a reduced notch, theslider 112 can be stabilized in the slidinggroove 111, and can bear the gravity of thesupport arm 120 and theradiation emitting device 200 or theradiation receiving device 300.

In this embodiment, thetelescoping mechanism 130 is a rack and pinion mechanism, including tworacks 131 and onegear 132. Thegear 132 is disposed in the middle of the slidinggroove 111 and rotatably mounted on themain body bracket 110. Thegear 132 is located between the tworacks 131 and is simultaneously engaged with the tworacks 131. The tworacks 131 are arranged along the length direction of the slidingchute 111 and are respectively close to two ends of the slidingchute 111, the tworacks 131 respectively correspond to the two slidingblocks 112 one by one, and one end of eachrack 131 far away from thegear 132 is fixedly connected with the corresponding slidingblock 112.

The tworacks 131 are respectively clamped between thegear 132 and a side groove wall of the slidingchute 111, a tooth surface of therack 131 faces thegear 132 and is engaged with thegear 132, and a surface of therack 131 facing away from the tooth surface respectively slides and abuts against a corresponding groove wall of the slidingchute 111. Thus, therack 131 is stably limited to maintain a stable sliding state.

Thegear 132 is mounted such that: as shown in fig. 7, theaxle 133 is inserted into the central hole of thegear 132, and the two are connected by a key 136. Thewheel shaft 133 is provided with abearing 135 and alimit clamp spring 137, which are respectively located outside two end faces of thegear 132. Wherein, the outer ring of thebearing 135 is fixed on the bottom of the C-shaped steel groove, and thelimit clamp spring 137 is close to the notch of the slidinggroove 111. Theaxle 133 extends out of the groove bottom of the C-shaped steel, and the extending end of theaxle 133 is formed with anoperation interface 134. In this embodiment, theoperation interface 134 is a quadrangular prism having a coaxial line with theaxle 133. Theoperator interface 134 allows the ROV robot or diver to rotate thegear 132 to adjust the twosupport arms 120 toward or away from each other.

The middle of themain body support 110 is also provided with anoperating handle 115, and theoperating handle 115 is positioned on the outer side of the bottom of the C-shaped steel groove, so that an ROV robot or a diver can conveniently hold the operation detector.

The sliding positioning mechanism includes amodule mounting seat 121, themodule mounting seat 121 is slidably disposed on thecorresponding support arm 120, and a locking mechanism is disposed between themodule mounting seat 121 and thesupport arm 120.

The cross section of the supportingarm 120 is a non-revolving body, themodule mounting seat 121 is slidably sleeved on the supportingarm 120, and an inner hole of themodule mounting seat 121 is matched with the cross section of the supportingarm 120 in shape. In this embodiment, as can be seen from fig. 4 and 8 to 11, the supportingarm 120 is a square tube, and themodule mounting seat 121 is a square tube, so that themodule mounting seat 121 cannot rotate relatively after being sleeved on the supportingarm 120.

A lockingbolt 122 penetrates through themodule mounting seat 121, the lockingbolt 122 is in threaded fit with themodule mounting seat 121 to form the locking mechanism, and a stud end of thelocking bolt 122 abuts against the correspondingsupport arm 120 to lock themodule mounting seat 121. Themodule mounting seat 121 is fixedly provided with theradiation emitting device 200 or theradiation receiving device 300. When the position of theradiation emitting device 200 or theradiation receiving device 300 needs to be adjusted along the length direction of thesupport arm 120, the lockingbolt 122 is loosened and themodule mounting base 121 is slid.

In addition, a position calibration component is disposed between the twomodule mounting seats 121, and the position calibration component is used for assisting in achieving the alignment between the twomodule mounting seats 121. The position calibration assembly may be composed of alaser 123 and alaser detector 124, which are respectively mounted on two of themodule mounting seats 121 and located on the surface of the correspondingmodule mounting seat 121 facing the inner hole of the adjusting frame. The laser light emitted by thelaser 123 is detected by thelaser detector 124, indicating that theradiation emitting device 200 and theradiation receiving device 300 are aligned.

As shown in fig. 8 and 9, theradiation emitting device 200 includes asource mounting housing 210 having an opening, a source mounting flange 220 is disposed on the opening of thesource mounting housing 210, aradiation emitting window 250 for gamma rays to pass through is disposed on the source mounting flange 220, and theradiation emitting window 250 closes a central hole of the source mounting flange 220, so that thesource mounting housing 210, the source mounting flange 220 and theradiation emitting window 250 form a sealed system.

Within thesource mounting housing 210 is a radiation source assembly that is externally coated with a source isolation kit of radiation absorbing material that positions the radiation source assembly within thesource mounting housing 210. Acollimation hole 241 is formed in the source isolation kit, and thecollimation hole 241 is opposite to the central hole of the source mounting flange 220, and is communicated with the central hole in a hole-sharing manner. The source isolation kit may be made of lead.

In order to facilitate the storage and transportation of theradiation emitting device 200, a protectingcover 290 made of a radiation absorbing material is detachably fastened to the source mounting flange 220, and the protectingcover 290 shields the source mounting flange 220 and theradiation emitting window 250. Theshield cover 290 covers the source mounting flange 220 and covers the interface of the source mounting flange 220 and thesource mounting enclosure 210.

The protectingcover 290 is thickened at the center to form a protectingtruncated cone 291, and the diameter of the protectingtruncated cone 291 is not smaller than the aperture of thecollimating hole 241, and is preferably equal to or larger than the diameter of theradiation emitting window 250. The thickness of theprotection round platform 291 is larger, so that the absorption of gamma rays at theray emission window 250 can be enhanced, and the safety is improved. Theshield cover 290 may also be made of lead.

The installation structure of theradiation emission window 250 is: the middle part of the outer side face of the source mounting flange 220 is provided with a ray window hole, the ray window hole is communicated with the central hole of the source mounting flange 220, a circularray emission window 250 and a ray windowpressing ring 221 are arranged in the ray window hole, theray emission window 250 and the ray windowpressing ring 221 are arranged on the same central line, the inner edge of the ray windowpressing ring 221 presses the edge of theray emission window 250, the inner side face of the ray windowpressing ring 221 abuts against the hole bottom of the ray window hole and is connected through a bolt, so that theray emission window 250 is pressed on the hole bottom of the ray window hole, and the central hole of the source mounting flange 220 is shielded in a sealing mode. The outer side face of theray emission window 250 and the outer side face of the raywindow compression ring 221 are both level with the outer side face of the source mounting flange 220.

In order to further enhance the sealing performance, the edge of the outer surface of theray emission window 250 is matched with the inner edge of the inner surface of the ray windowpressing ring 221 in a step mode. The middle of the bottom of the ray window hole protrudes outwards to form a sealingconvex ring 222 surrounding the central hole of the source mounting flange 220, the middle of the inner surface of theray emission window 250 is thinned corresponding to the sealingconvex ring 222 to form a counter bore, the bottom of the counter bore abuts against the sealingconvex ring 222, and the wall of the counter bore abuts against the annular outer wall of the sealingconvex ring 222.

In this embodiment, thesource mounting housing 210 is a hollow cylinder with an opening at one end, the source mounting flange 220 is disposed on the opening of thesource mounting housing 210, a portion of the source mounting flange 220 facing the inner cavity of thesource mounting housing 210 protrudes inward to form a boss 223, and an annular sidewall of the boss 223 abuts against an inner side surface of the opening of thesource mounting housing 210. The source mounting flange 220 is bolted to thesource mounting housing 210 with the boss 223 abutting the source isolation kit.

The source isolation kit comprises a hollow cylindrical source isolation sleeve 230, an inner cavity of the source isolation sleeve 230 is opened on one end face, an annular source isolation pad 240 is covered on the end face in a buckling mode, the outer diameter of the source isolation pad 240 is equal to that of the source isolation sleeve 230, and the outer cylindrical surfaces of the source isolation pad 240 and the source isolation sleeve 230 are attached to the inner wall cylindrical surface of thesource installation shell 210. The source spacer 230 has a shape fitting the source assembly disposed in the inner cavity thereof, and the inner diameter of the source spacer 240 is smaller than the inner diameter of the source spacer 230, so as to confine the source assembly in the source spacer 230.

The inner bore of the source spacer 230 forms thecollimating bore 241.

The radioactive source assembly comprises asource installation cabin 260, the outer wall of thesource installation cabin 260 is matched with the shape of the inner cavity of the source isolation sleeve 230, aradioactive source 280 is arranged in thesource installation cabin 260, a radiation outlet 261 axially communicated with thecollimation hole 241 is formed in the bulkhead of thesource installation cabin 260 corresponding to thecollimation hole 241, an arrangement hole for theradioactive source 280 to enter thesource installation cabin 260 is formed in the bulkhead of thesource installation cabin 260, a source setscrew 270 is arranged in the arrangement hole, the source setscrew 270 is in threaded fit with the arrangement hole, and asource pad 271 is arranged between the screw column end of the source setscrew 270 and theradioactive source 280.

The outer wall of the source mounthousing 210 is fixedly attached, such as welded, to thecorresponding module mount 121. The wholeray emission device 200 is compact in structure, good in sealing performance and convenient to use underwater.

As shown in fig. 10 and 11, theradiation receiving device 300 includes a receivingunit housing 310, and the receivingunit housing 310 is opened with a receivinghole 311 and a crystal placing hole. The receivingaperture 311 is sealed by a receivingunit radiation window 330 and the crystal access aperture is covered with a receivingunit flange cover 320, thereby forming a closed cavity within the receivingunit housing 310. A crystal 360 and a crystal positioning component are arranged in the closed cavity, the crystal positioning component positions the crystal 360 in the receivingunit shell 310, and the crystal 360 is opposite to the receivingunit ray window 330.

In this embodiment, the receivingunit housing 310 is cylindrical, an inner wall of one end of the receivingunit housing 310 is radially contracted to form a limitingring 312, an inner hole of the limitingring 312 forms the receivinghole 311, and an opening of the other end of the receivingunit housing 310 forms the crystal insertion hole. A receivingunit ray window 330, a pressing ring 340 and a crystal 360 are sequentially arranged in the receivingunit shell 310 from the receivinghole 311 to the crystal placing hole, and a crystal positioning component is arranged outside the crystal 360.

The aperture of the receivingaperture 311 is larger than that of thecollimating aperture 241 in consideration of the divergence of the ray bundle during propagation.

The receivingunit flange cover 320 is connected to the receivingunit housing 310 by bolts, and the inner side surface of the receivingunit flange cover 320 presses the crystal 360, so that the pressing ring 340 presses the edge of the receivingunit ray window 330 against the limitingring 312.

The outer diameter of the receivingunit ray window 330 is the same as the inner diameter of the receivingunit housing 310, and the outer side surface of the receivingunit ray window 330 is in stepped fit with the limitingring 312 to improve the assembly sealing performance. The inside surface edge of receivingelement ray window 330 forms has annular step, this annular step with clamping ring 340 looks adaptation, clamping ring 340 with be provided with between receivingelement flange cover 320 the crystal locating component with crystal 360.

The crystal 360 is cylindrical, with one end facing the receivingunit radiation window 330 and the other end abutting against the inner side of the receivingunit flange cover 320. The crystal positioning assembly includes a resilient crystal holding sleeve 350 and anend positioning ring 321. The crystal fixing sleeve 350 is sleeved on the end of the receivingunit ray window 330 facing the crystal 360, the crystal fixing sleeve 350 is clamped between the inner wall of the receivingunit casing 310 and the circumferential surface of the outer wall of the crystal 360, the crystal fixing sleeve 350 faces one end of the pressing ring 340, anelastic ring pad 351 is integrally formed, and theelastic ring pad 351 is clamped between the pressing ring 340 and the end face of the receivingunit ray window 330 facing the crystal 360. The crystal 360 is protected by the elasticity of the crystal fixing sleeve 350 and theelastic ring pad 351.

Theend positioning ring 321 is sleeved on the end of the crystal 360 close to the receivingunit flange cover 320, and the outer wall of theend positioning ring 321 is attached to the inner wall of the receivingunit housing 310.

Theend positioning ring 321 and the crystal holding sleeve 350 fix their radial positions from both ends of the crystal 360, respectively.

Theend positioning ring 321 is integrally formed on the inner side surface of the receivingunit flange cover 320, a ring groove is formed in the circumferential surface of the outer wall of theend positioning ring 321, a sealingring 322 is arranged in the ring groove, and theend positioning ring 321 and the contact surface between the receivingunit shells 310 are sealed by the sealingring 322.

During detection, theprotective cover 290 is removed, and the ROV robot or diver pushes the opening of the adjustingframe 100 of the detector to face the conduit to be detected, so that theradiation emitting device 200 and theradiation receiving device 300 are respectively positioned at two sides of the central line of the conduit, and then detection is performed, as shown in fig. 1. Theradiation emitting device 200 and theradiation receiving device 300 are adjusted to proper positions, as needed, the distance between the two is recorded as D,

. After passing through the tested conduit, the gamma ray beam emitted by theray emitting device 200 is received by theray receiving device 300, and the thickness of the seawater layer in the conduit cavity of the tested part is calculated according to the thickness of the seawater layer, so that whether water enters the conduit or not is inferred.

Finally, it should be noted that the above-mentioned description is only a preferred embodiment of the present invention, and those skilled in the art can make various similar representations without departing from the spirit and scope of the present invention.

Claims (10)

1. A method for detecting water leakage of a jacket of an offshore platform is characterized by comprising the following steps: scanning a to-be-detected part of a jacket by using gamma ray detection equipment, wherein the gamma ray detection equipment comprises an adjusting frame (100), a ray transmitting device (200) and a ray receiving device (300), and during detection, the to-be-detected part is positioned between the ray transmitting device (200) and the ray receiving device (300) and the initial intensity and the receiving intensity of gamma rays are recorded;

calibrating the absorption correlation coefficient of the marine organisms to the gamma rays in advance, measuring the thickness of the marine organisms of a part to be measured, measuring the thickness of a seawater layer between the ray transmitting device (200) and the ray receiving device (300) outside a conduit of the part to be measured, and measuring or inquiring to obtain the absorption correlation coefficient of the wall of the conduit to the gamma rays and the absorption correlation coefficient of seawater to the gamma rays;

and calculating to obtain the thickness of the seawater layer in the inner cavity of the to-be-measured part of the jacket according to the initial intensity, the receiving intensity, the thickness of the marine organism, the thickness of the seawater layer outside the to-be-measured part of the jacket and the absorption correlation coefficient of the marine organism, the jacket wall and the seawater on the gamma rays based on the material absorption attenuation rule of the gamma rays.

2. The offshore platform jacket water leakage detection method according to claim 1, characterized by comprising the following steps:

step one, scanning a to-be-detected part of a jacket by adopting gamma ray detection equipment according to a set plan;

wherein the radiation emitting device (200) emits an initial intensity of

And the gamma ray passes through the part to be detected, and the ray receiving device (300) receives and detects the intensity of the ray passing through the part to be detected

；

Step two, pre-measuring the thickness of marine organisms attached to the outer wall of the conduit of the sea area where the jacket is located

The thickness of the wet marine organisms attached to the outer wall of the vessel below the sea surface is recorded

The thickness of the dry marine organism attached to the outer wall of the conduit above the sea surface is

；

Simultaneously, according to the absorption and attenuation law of gamma ray substances, the average absorption coefficient of marine organisms is respectively calibrated

Wherein the average absorption coefficient of wet marine organisms is recorded as

The average absorption coefficient of the dry marine organisms is recorded as

；

Then carrying out the third step or the fourth step;

step three, calculating the thickness of the accumulated water in the inner cavity of the part to be measured immersed in the seawater by adopting the following formula

：

（Ⅰ），

In formula (I):

is a ray emitting device (200) and a ray receiving device (300) of the testing device and is positioned outside the pipe wall of the part to be testedThe thickness of the seawater layer of (a);

is the density of seawater;

the mass absorption coefficient of seawater to gamma rays;

2 times the jacket wall thickness;

is the jacket wall density;

is the mass absorption coefficient of the pipe wall of the jacket;

the density of accumulated water in the to-be-measured part of the jacket,

；

is the mass absorption coefficient of accumulated water in the part to be measured of the jacket,

；

wherein

Are all of the parameters which are known, and are,

calculated as follows:

（Ⅱ）；

in formula (II): d is the distance between the ray transmitting device (200) and the ray receiving device (300),

the outer diameter of the catheter at the part to be measured;

step four, calculating the thickness of the accumulated water of the part to be measured exposed on the sea surface by adopting the following formula

：

（Ⅲ）；

Step five, calculating in the step three or the step four

Or

The value of (D) and the inner diameter of the catheter at the position to be measured

And comparing to determine the water inlet degree of the inner cavity of the part to be detected.

3. The offshore platform jacket water leakage detection method according to claim 2, wherein in the second step, the calibration method of the average absorption coefficient of the wet sea creatures and the dry sea creatures comprises the following steps:

taking the container, filling a certain amount of marine life into the container, keeping the surface flat, and recording the height of the marine life

The ray emitting device (200) and the ray receiving device (300) are respectively close to the bottom surface of the container and the surface of the marine organism, and the ray intensity is obtained through detection

The average absorption coefficient of the dried marine organisms was calculated according to the following formula (IV)

，

（Ⅳ）；

Adding seawater into the container until the seawater just submerges the upper surface of the marine organism, and detecting the ray intensity again

The average absorption coefficient of wet marine organisms was calculated according to the following formula (V)

；

（Ⅴ）。

4. The offshore platform jacket water leakage detection method of claim 3, wherein: the part to be measured is a circular tube, and in the first step, a connecting line of the ray transmitting device (200) and the ray receiving device (300) passes through the center of the circular tube so that gamma rays pass through the circular tube along the diameter direction of the circular tube.

5. The offshore platform jacket water leakage detection method of claim 4, wherein: in the fifth step, the water inlet degree of the inner cavity of the part to be detected is determined according to the following method:

computing

Or

And

the ratio of the values, and the water inflow percentage of the inner cavity of the part to be detected is judged according to the ratio of the values

D takes on the value of

Or

。

6. The offshore platform jacket water leakage detection method of claim 4, wherein: the adjusting frame (100) is an open frame with an opening, the ray emitting device (200) and the ray receiving device (300) are respectively arranged on the adjusting frame (100) on two sides of the opening, and the ray emitting device (200) and the ray receiving device (300) are arranged in a right-to-right mode;

the ray emitting device (200) and the ray receiving device (300) are respectively arranged on the adjusting frame (100) through a sliding positioning mechanism, and the sliding positioning mechanism is used for adjusting the ray emitting device (200) and the ray receiving device (300) to be close to or far away from the opening;

the adjusting frame (100) is provided with an adjusting device which is used for adjusting the ray emitting device (200) and the ray receiving device (300) to be close to or far away from each other;

in the first step, the distance between the ray emitting device (200) and the ray receiving device (300) is adjusted to a proper size through the adjusting device, and the size is recorded as D.

7. The offshore platform jacket water leakage detection method of claim 6, wherein: the adjusting frame (100) comprises a main body support (110) and two supporting arms (120), the two supporting arms (120) are arranged oppositely in parallel, the same end of the two supporting arms (120) is connected with the main body support (110), and the other ends of the two supporting arms (120) extend out to the same side of the main body support (110), so that the adjusting frame (100) with an opening on one side is formed by the adjusting frame and the main body support (110);

the main body bracket (110) is provided with the adjusting device which is connected with the two supporting arms (120);

the ray emitting device (200) is arranged on one of the supporting arms (120) through one of the sliding positioning mechanisms, and the ray receiving device (300) is arranged on the other supporting arm (120) through the other sliding positioning mechanism.

8. The offshore platform jacket water leakage detection method of claim 7, wherein: the sliding positioning mechanism comprises a module mounting seat (121), the module mounting seat (121) is slidably arranged on the corresponding supporting arm (120), and a locking mechanism is arranged between the module mounting seat (121) and the supporting arm (120);

a position calibration component is arranged between the two module mounting seats (121), in the first step, the position of the two module mounting seats (121) on the supporting arm (120) is adjusted by the position calibration component, so that the two module mounting seats (121) are opposite, and then the distance between the ray transmitting device (200) and the ray receiving device (300) is adjusted.

9. The offshore platform jacket water leakage detection method of claim 8, wherein: the cross section of the supporting arm (120) is a non-revolving body, the module mounting seat (121) is slidably sleeved on the supporting arm (120), the shape of an inner hole of the module mounting seat (121) is matched with that of the cross section of the supporting arm (120), a locking bolt (122) penetrates through the module mounting seat (121), the locking bolt (122) is in threaded fit with the module mounting seat (121) to form the locking mechanism, and the stud end of the locking bolt (122) abuts against the corresponding supporting arm (120) to lock the module mounting seat (121);

the module mounting seat (121) is fixedly provided with the ray transmitting device (200) or the ray receiving device (300).

10. The offshore platform jacket water leak detection method of claim 9, wherein: the adjusting device comprises a sliding mechanism and a telescopic mechanism (130);

one sliding mechanism is arranged between each supporting arm (120) and the main body support (110), and the two sliding mechanisms guide the two supporting arms (120) to slide along the connecting direction of the connecting ends of the two supporting arms;

the telescopic mechanism (130) is connected between the sliding parts of the two sliding mechanisms.

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