CN111119865A - Method for visually finding leakage of casing damage well underground nitrogen gas lift negative pressure - Google Patents
Method for visually finding leakage of casing damage well underground nitrogen gas lift negative pressure Download PDFInfo
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- CN111119865A CN111119865A CN201911407254.4A CN201911407254A CN111119865A CN 111119865 A CN111119865 A CN 111119865A CN 201911407254 A CN201911407254 A CN 201911407254A CN 111119865 A CN111119865 A CN 111119865A
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Abstract
The invention belongs to the technical field of underground leakage finding, and particularly relates to an underground nitrogen gas lift negative pressure visual leakage finding method for a casing damage well. The method comprises the following steps of drifting by using a drift size; plugging the perforation section; lowering the pipe column to pressurize after well flushing to ensure bridge plug setting; sealing the well mouth; lowering a gas-lift pipe column, and lowering a visual logging instrument in the gas-lift pipe column until the visual logging instrument extends out of a bell mouth of the gas-lift pipe column; introducing nitrogen into the annular space between the gas lift pipe column and the sleeve for gas lift; forming negative pressure between the casing and the stratum, and slowly lowering a visual logging instrument; and observing the condition of the missing points. The leakage finding efficiency of the casing pipe is higher, the construction cost is lower, the leakage finding time is obviously saved, the safety is better, and the visualization of underground leakage points is realized.
Description
Technical Field
The invention belongs to the technical field of underground leakage finding, and particularly relates to an underground nitrogen gas lift negative pressure visual leakage finding method for a casing damage well.
Background
Cased hole, also known as a casing damaged well. In the prior art, water and leakage detection for casing damage wells is mostly completed by production profile well logging, saturation well logging or engineering well logging. The production profile well logging technology is the water exploration technology which is most widely applied and has the best effect, the production profile well logging is to measure parameters such as flow rate, fluid components, pressure, temperature and the like of a shaft under the condition of oil well production, and the quantity and the property of fluid produced by each layer are calculated by methods such as templates, models, experimental data analysis and the like. However, the well logging of the output profile is complicated in construction steps, and the output results of all layers, such as the combined layer liquid production amount, the combined layer oil production amount, the combined layer water production amount, the combined layer gas production amount and the like, need to be calculated, then the output of the layered oil, gas and water is calculated, and finally the position of the damaged sleeve is judged according to the liquid production profile data of all layers. The construction cost is high, the workload is large, the positioning accuracy of the damaged position of the sleeve detected by analysis is poor, the damaged quantity and the damaged size cannot be accurately judged, damaged points are easy to miss, and the rework rate is high.
Disclosure of Invention
The embodiment of the invention provides a method for visually finding leakage of a casing damage well through underground nitrogen gas lift negative pressure, and solves the technical problems that the method for finding leakage of a casing damage well in the prior art is low in efficiency, high in construction cost and incapable of realizing visual images.
In order to achieve the above object, an embodiment of the present invention provides a method for visually detecting leakage of a casing damage well downhole under a nitrogen gas lift negative pressure, comprising the following steps,
drifting and scraping by using a drift size gauge;
plugging the perforation section;
after well flushing, putting a pipe column down for pressure test to ensure bridge plug setting;
sealing the well mouth;
lowering a gas-lift pipe column, and lowering a visual logging instrument in the gas-lift pipe column until the visual logging instrument extends out of a bell mouth of the gas-lift pipe column;
introducing nitrogen into an annular space between the gas lift pipe column and the sleeve for gas lift, and observing the liquid discharge condition of an outlet;
after negative pressure is formed between the casing and the stratum, the visual logging instrument is continuously and slowly lowered; according to image information transmitted by a visual logging instrument, directly observing the casing wall condition, and recording and feeding back the water or oil outlet position of the casing and related information; the water or oil outlet position of the sleeve is the damaged position.
Further, the method for finding the leakage of the casing damage well through the visualization of the underground nitrogen gas lift negative pressure comprises the following steps of (1) taking out an original well pipe column; (2) drifting and scraping by using a drift size gauge; (3) drilling a bridge plug to plug the perforation section; (4) a well washing pipe column is lowered to wash the well until the water quality in and out is close; (5) installing a KZ65-25 wellhead device, and testing the pressure test of the wellhead to detect the sealing condition; (6) one end of a valve inlet check valve of the KZ65-25 wellhead device is connected with a nitrogen making vehicle pipeline, the outlet of the other end of the valve inlet check valve is connected with a liquid storage tank, the outlet of an oil pipe valve is connected with the liquid storage tank through an oil pipe, and pressure testing is carried out after the wellhead pipeline is connected; (7) installing a wellhead lubricator; (8) lowering the gas-lift pipe column, and then lowering the visual logging instrument from the gas-lift pipe column until the visual logging instrument extends out of the bell mouth of the gas-lift pipe column; (9) opening a valve, starting a nitrogen making vehicle, introducing nitrogen into an annular space between a gas lift pipe column and a sleeve for gas lift, and observing the liquid discharge condition of a liquid discharge port of the gas lift pipe column; (10) after the gas lift is carried out for 5-40min, continuously and slowly lowering the visual logging instrument under the condition of keeping the gas lift, and observing the casing wall; according to image information transmitted by a visual logging instrument, directly observing the casing wall condition, and recording and feeding back the water or oil outlet position of the casing and related information; (11) the water or oil outlet position of the sleeve is the leakage point position.
Further, in the step (5), the pressure of the seal test is 10MPa, and the pressure drop is less than 0.5MPa after 5 minutes of the test.
Furthermore, an earth anchor is arranged on an oil pipe which connects the outlet of the oil pipe valve and the liquid storage tank in the step (6).
Further, the well-flushing discharge capacity of the running water in the step (4) is 400-800L/min.
Further, the speed of the visual logging instrument placed downwards in the step (8) is less than 50 m/min.
Furthermore, in the process of lowering the visual logging instrument to observe the casing wall, a stop point observation method is adopted, the stop point distance is 1-10 meters, and the stop point time is 1-10 minutes.
Furthermore, in the process of observing a stop point through a visual logging instrument, the direction of water flow is judged through a water direction mark on the visual logging instrument, and then the relative position of a leak point and an observation point is judged according to the direction of the water flow; the well fluid flows upwards, and the leakage point is below; turbulent flow occurs in well fluid, and a water outlet point is arranged nearby; the well fluid has no fluidity, and a water outlet point is not arranged below the well fluid; the water drifts transversely to the mark and/or the water quality suddenly becomes better in transmittance, and a leakage point is arranged nearby.
Further, the visual logging instrument is a self-cleaning lens visual logging instrument.
Further, the visual logging instrument is a self-cleaning light source visual logging instrument.
Compared with the prior art, the technical scheme of the embodiment of the invention has the beneficial effects that: the casing leakage finding efficiency is higher, the construction cost is lower, the leakage finding time is remarkably saved, the safety is better, the visualization of underground leakage points is realized, the realization is achieved, and the technical problems that the detection method in the prior art is easy to miss detection and needs to be repeatedly reworked for detection under the condition that a plurality of leakage points exist in the casing are effectively prevented.
Drawings
FIG. 1 is a working principle diagram of equipment in a casing damage well downhole nitrogen gas lift negative pressure visualization leak finding method according to an embodiment of the invention.
FIG. 2 is a photograph of a missing dot image taken by a visual logging tool in accordance with an embodiment of the present invention.
Description of reference numerals: 1. a lubricator; 2. KZ65-25 wellhead; 3. logging a well truck; 4. a liquid storage tank; 5. nitrogen making vehicle; 6. a sleeve; 7. a gas lift column; 8. VideoLog LR2019 visualization logging instrument; 9. a perforation section.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terms "first" and "second," and the like, in the description and in the claims of embodiments of the present invention are used for distinguishing between different objects and not for describing a particular order of the objects. For example, the first parameter set and the second parameter set, etc. are used to distinguish different parameter sets, rather than to describe a particular order of parameter sets.
In the description of the embodiments of the present invention, the meaning of "a plurality" means two or more unless otherwise specified. For example, a plurality of elements refers to two elements or more.
The term "and/or" herein is an association relationship describing an associated object, and means that there may be three relationships, for example, a display panel and/or a backlight, which may mean: there are three cases of a display panel alone, a display panel and a backlight at the same time, and a backlight alone. The symbol "/" herein denotes a relationship in which the associated object is or, for example, input/output denotes input or output.
In the embodiments of the present invention, words such as "exemplary" or "for example" are used to mean serving as examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "e.g.," an embodiment of the present invention is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, use of the word "exemplary" or "such as" is intended to present concepts related in a concrete fashion.
The embodiment of the invention provides a method for visually finding leakage of a casing damage well downhole nitrogen gas lift negative pressure, which comprises the following steps of descending a gas lift pipe column, and lowering a visual logging instrument in the gas lift pipe column until the visual logging instrument extends out of a bell mouth of the gas lift pipe column; firstly, drifting and scraping by using a drift size gauge; secondly, plugging the perforation section; then, after well washing, the pipe column is lowered down to test pressure, and bridge plug setting is ensured; then sealing the well mouth; then, lowering the gas-lift pipe column, and then lowering the visual logging instrument in the gas-lift pipe column until the visual logging instrument extends out of the bell mouth of the gas-lift pipe column; then introducing nitrogen into the annular space between the gas lift pipe column and the sleeve for gas lift, and observing the liquid discharge condition of the outlet; negative pressure is formed between the sleeve and the stratum, and the liquid discharge amount of the outlet is stable; finally, continuously and slowly lowering the visual logging instrument under the condition of keeping the gas lift; and (3) transmitting image information according to a visual logging instrument, directly observing the casing wall condition, recording and feeding back the water or oil outlet position of the casing and related information, wherein the water or oil outlet position of the casing is the damaged position.
In the embodiment, the pipe column is kept smooth when the pipe column in the well is lowered after the well is pigged by the pigging gauge, and then the perforation section is plugged, so that the casing pipe is sealed as much as possible; then, washing the well to remove oil stains and mud ash from the casing, keeping the casing clean and facilitating the next step of clearly observing the casing leakage point condition; the well head seals the back and pours into nitrogen gas into through the nitrogen-making car to the annular space part between gas lift tubular column and the sleeve pipe, thereby extrude in the liquid in the annular space part from the gas lift tubular column, thereby form the negative pressure between annular space part and stratum, because the existence of negative pressure, water in the bottom, oil or other fluid can flow into the sleeve pipe along the leak source under the effect of pressure in, thereby the sheathed tube in-process is observed to the visual logging instrument of rethread, if the casing pipe appears the gassing, perhaps oil seepage that just explains here sleeve pipe damage has the leak source, finally through visual logging instrument, thereby pass through cable transmission to ground with video image information. Therefore, specific bushing leak point position, size and leak point type information are obtained through image video information analysis, and the practical purpose is achieved.
Through this embodiment technical scheme, make the sleeve pipe find leak efficiently, construction cost is lower, is showing to have practiced thrift and has given for leaks the time, and the security is better to realized the visualization of leaking the point in the pit, realized the eye is true, effectively prevent in its condition that the sleeve pipe has a plurality of leaking points, the technical problem that the detection method among the prior art needs the repeated rework detection.
In an embodiment of the invention, as shown in fig. 1, the method for visually finding leakage of a casing damage well downhole under nitrogen gas lift negative pressure specifically comprises the following steps of (1) pulling out an original well pipe column; (2) the well is pigged by a pigging gauge; (3) a bridge plug is punched to block the perforation section 9; (4) a well washing pipe column is lowered to wash the well until the water quality in and out is consistent; (5) installing a KZ65-25 wellhead device 2, and testing the pressure test of the wellhead to detect the sealing condition; (6) one end of a valve inlet check valve of the KZ65-25 well head device 2 is connected with a nitrogen making vehicle pipeline, the outlet of the other end of the valve inlet check valve is connected with the liquid storage tank 4, the outlet of an oil pipe valve is connected with the liquid storage tank 4 through an oil pipe, and pressure testing is carried out after the well head pipeline is connected; (7) installing a wellhead lubricator 1; (8) a gas-lift pipe column 7 is lowered, then the VideoLog LR2019 visual logging instrument 8 is lowered from the gas-lift pipe column 7 until the visual logging instrument extends out of a bell mouth of the gas-lift pipe column; (9) opening a valve, starting the nitrogen making vehicle 5, introducing nitrogen into an annular space between the gas lift pipe column 7 and the sleeve 6 for gas lift, and observing the liquid discharge condition of a liquid discharge port of the gas lift pipe column 7; (10) after gas lift is carried out for 20min, stopping gas lift after liquid drainage is stable or under the condition that no liquid drainage is discharged, slowly lowering the VideoLog LR2019 visual logging instrument 8, and observing the side wall of the casing 6 in the lowering process; transmitting image information according to the VideoLog LR2019 visual logging instrument 8, directly observing the casing wall condition, and recording and feeding back the water or oil outlet position and related information of the casing 6; (11) the water or oil outlet position of the sleeve 6 is the leak position.
Illustratively, after the gas lift is performed for 20min in the step (10), after the liquid discharge is stable, or in the case of no liquid discharge, the gas lift is continued, and the VideoLog LR2019 is slowly lowered.
In the selected embodiment of the invention, the pressure of the seal test and the pressure test in the step (5) are 10MPa, and the pressure drop of the seal test and the pressure test is less than 0.5MPa after 5 minutes. Thereby ensuring the formation of a subsequent negative pressure by the degree of sealing.
In an optional embodiment of the invention, in the step (6), an earth anchor is arranged on an oil pipe connecting the outlet of the oil pipe valve and the liquid storage tank. Thereby effectively fixing the connecting oil pipe and preventing falling off.
In an optional embodiment of the present invention, the well-flushing displacement of the flowing water in the step (4) is 400-800L/min. The optimal selection is 600L/min, so that sewage and oil stains in the well are discharged under the condition of saving water resources, the discharge amount of well washing water is not too small and is not too large, the oil stains on leak points cannot be quickly cleaned when the discharge amount of well washing water is too small, and a large amount of water resources are wasted when the discharge amount of well washing water is too large.
In an optional embodiment of the present invention, in the step (8), the speed of the visual logging instrument placed downwards is less than 50 m/min. The lower speed is kept at 50m/min to basically meet the requirement, the observation effect is influenced due to the too high speed, and unsafe accidents can be caused due to the rapid downward movement. Too slow a speed can seriously affect the detection efficiency. Of course, the speed is also a relatively proper speed after the test of the invention and cannot be realized without representing other running speeds.
In an optional embodiment of the invention, in the process of lowering the visual logging instrument to observe the casing wall, a stop point observation method is adopted, the stop point distance is 1-10 m, and the stop point time is 1-10 minutes. Through the observation of the stop point, combine water to mark the judgement method again to can be more rapid find the leak source place, compare at the uniform velocity observation method detection efficiency and improve greatly, can more efficient screen remove, the casing section that does not have the leak source.
In an optional embodiment of the invention, in the process of observing a stop point by using the VideoLog LR2019 to visualize the logging instrument 8, the water direction is judged by using the VideoLog LR2019 to visualize the water beacon on the logging instrument 8, and then the leak point is judged to be the relative position with the observation point according to the water direction; the well fluid flows upwards, and the leakage point is below; turbulent flow occurs in well fluid, and a water outlet point is arranged nearby; the well fluid has no fluidity, and a water outlet point is not arranged below the well fluid; the water drifts transversely to the mark and/or the water quality suddenly becomes better in transmittance, and a leakage point is arranged nearby. Thereby combining a fixed-point observation method, the detection efficiency of the embodiment of the invention can be obviously improved,
in an optional embodiment of the invention, the visual logging instrument is a self-cleaning lens visual logging instrument, and the visual logging instrument with the self-cleaning lens can better solve the technical problem that the visual logging instrument is easily affected by pollutants during the lowering work process, so that the later-stage observation is unclear. .
In an optional embodiment of the present invention, the visual logging instrument is a self-cleaning light source visual logging instrument, and the application of the self-cleaning light source visual logging instrument effectively avoids the technical problem that the observation result is affected after the light source is polluted in the application process of the visual logging instrument.
In one embodiment of the invention, video image information transmitted by a visual logging instrument is interfaced with an artificial intelligence machine learning system. The visual logging instrument transmits the collected video image information to the machine learning system, the machine learning system constructs a machine learning model of casing leak detection after learning, and then a casing damage well underground nitrogen gas lift negative pressure visual leak detection model is formed. And in the process of visual leakage detection of the casing, the casing damage is directly and automatically analyzed through the visual leakage detection model of the underground nitrogen gas lift negative pressure of the casing damage well, so that intelligent detection is realized. And when the collected video image information shows the damage judged in the casing damage well underground nitrogen gas lift negative pressure visual leakage detection model, giving an alarm or recording. Therefore, in the later well repairing process, the image information of the damaged section is directly watched, or the well repairing maintenance is carried out according to the damaged condition obtained by system analysis. The technical problem of manual long-time watching is effectively solved, and the leakage detection efficiency is improved.
By the method for finding the leakage of the casing damage well under the nitrogen gas lift negative pressure visualization system, the detection efficiency of the leakage point in the casing damage well can be greatly improved. In the detection method in the prior art, the basic detection time is over 72 hours, but the invention shortens the time within 6 hours in the actual application process, realizes the visual detection of the leakage point, directly acquires the image information of the leakage point and directly acquires the accurate position, shape and damage reason of the leakage point. Compared with the industrial profile method in the prior art, the method is high in efficiency, can quickly detect and discover multipoint damage, and can form negative pressure near the leaking point through the combined application of the visualization technology and the nitrogen gas lift method, so that the leaking point is drained at a high speed, the visualization of the leaking point of the damaged part is effectively realized, the position, the size, the shape and the number of the leaking point can be visually observed, and a powerful technical support is provided for further repairing the cased damaged well.
In one embodiment of the present invention, a specific construction process for the 295-289 well is provided.
The daily production liquid before the well casing is broken is 3.91m32.15t of daily oil production, 34.6 percent of water content, high yield, 3.6m of oil layer thickness of 8 layers of exploitation extension and good reservoir physical property, and corresponds to 1 port of a water injection well and integrates water injection 6464m3And the energy of the region is sufficient. In order to restore the single well productivity, give full play to the potential of an oil layer, verify the negative pressure visual well logging, leakage detection and well logging process, provide reliable basis for the formulation of later treatment measures, realize the effective treatment of casing damage wells, and research and decision on developing a negative pressure visual well logging, leakage detection and test in the well.
The technical scheme is as follows: the method comprises the steps of putting a gas lift pipe column with a bell mouth into an oil well 100-200 m below the normal liquid level, putting a visual logging instrument into the gas lift pipe column through a cable until the visual logging instrument goes out of the bell mouth, injecting high-pressure nitrogen into the annular space of a logging oil sleeve to reduce the density of liquid in the shaft, so that the pressure balance in the shaft is damaged, reducing the pressure of the shaft, enabling the liquid to flow out of holes such as a perforation section and a sleeve breaking point under the action of negative pressure, lowering the visual logging instrument to observe the flowing condition of the sleeve breaking point liquid outlet between the gas lift pipe mouth and the perforation section while maintaining gas lift, transmitting a seepage picture of the inner wall of the shaft sleeve back to a ground instrument through the visual logging instrument, and determining the sleeve breaking point of the shaft through observation, analysis and judgment.
Preparing equipment: wellhead device and matched tool, 30m3The liquid storage tank 2 is used for washing a well to prepare 15m of active water (clear water, 0.3 percent of CF-5D and 0.3 percent of COP-1)3And all tanks are cleaned, one 40T well repairing vehicle is used, one 700-type pump vehicle is used (the highest pressure is not lower than 30MPa, all vehicle conditions are required to be good, flushing tools such as valves, ground pipelines, joints, movable elbows and the like are complete and intact), a well killing blowout manifold, fire-fighting equipment and well control equipment (according to the risk judgment of the well, the well is determined to be a 3-level risk well of an oil field, and the well control equipment is required to be equipped according to 25 MPa), and a phi 73mm tool oil pipe 1600m is used. The matched tool mainly comprises a phi 118mm multiplied by 2m throughWell gauge, GX140T tubing scrapers, and the like.
Prepare one of the bridge plugs suitable for plugging 51/2 "casing for plugging the perforated section.
27/8', 1 bell mouth, 1 KZ65-25 type water injection well mouth, and the total length of phi 73mmNU oil pipe short joints (0.2m, 0.5m and 1.0m) is accumulated to exceed the length of one oil pipe.
The common tools and fire-fighting equipment are completely prepared according to the normal construction requirement. The labor protection protective equipment (rubber gloves, gas masks, goggles, masks, towels, etc.) is complete.
1 type 700 liquid nitrogen vehicle, 1 nitrogen gas heating and pressurizing pry, 1 logging vehicle and 1 engineering service vehicle.
The VideoLog visual logging instrument is developed by the Western-Ann Petroleum university and is also called a VideoLog oil-gas well visual logging system, a detection probe of the VideoLog visual logging instrument resists pressure of 50MPa, resists temperature of 125 ℃ and has an outer diameter of 54mm, network high-speed video transmission is realized, the speed can reach 2Mbps cable self-adaption, the visual logging instrument can be rapidly adapted to logging cables of various specifications, real-time color videos are obtained, and the frame rate can reach 25 fps.
Table 1 is the related art parameters for the aboveground portion of the VideoLog visualization logging instrument.
| Model number | VideoLog-VLP2 |
| Mechanical dimensions | 51mm×53mm×23mm |
| Weight (kg) | 15 |
| Supply voltage | AC 220V |
| Ambient temperature | 0℃—40℃ |
| Underground power supply | 300V，1A；DC |
| Cable remote transmission system | 5.6M cable high speed telemetry |
| Display interface | VGA |
| Storage capacity | 1T hard disk |
| Host interface | RJ 45100M/1000M Ethernet |
| Depth interface | The photoelectric encoder outputs A, B signal, TTL level |
| Software platform | win7，win8，win10 |
Table 2 is VideoLog visualization tool downhole tool technical parameters.
Next, the original well production string is tripped out, each tubing is flushed clean, checked with a drift gauge having an outer diameter of 58mm, and the unqualified tubing is replaced.
And (4) drifting to the bottom of the artificial well (2068m) by a drifting gauge with the outer diameter of 118mm or 2000 mm.
And (3) drilling a bridge plug at a position of 1880m to plug the perforation section, so as to prevent oil from flowing out of the perforation section to pollute an oil layer.
Washing the well with active water 15m3And washing the well with active water at a discharge capacity of 600L/min, returning out impurities in the shaft until the water quality in and out is consistent, and strictly executing the standard requirements of well washing in the Changqing oil field. And after the well washing is finished, lowering the pipe column, pressurizing and detecting whether the bridge plug is successfully set.
A downhole visual leakage finding step:
① installing KZ65-25 wellhead device and testing wellhead sealing condition.
The ② KZ65-25 valve inlet check valve end is connected with a nitrogen making vehicle pipeline, the other end outlet is connected with a liquid storage tank, the connection between the oil pipe valve outlet and the liquid storage tank must adopt an oil pipe for connection and an earth anchor is arranged, the pressure test is 10MPa after the well mouth pipeline is connected, and the pressure drop is not more than 0.5MPa after 5 minutes of pressure test.
③ the blowout preventer and blowout preventer are installed on the well mouth, and the joints should be well sealed and not leak.
④ lowering the gas lift pipe column to 1290m, and lowering the visual logging instrument in the gas lift pipe column by using a cable until the visual logging instrument goes out of the bell mouth of the gas lift pipe column to 1300m, and the lowering speed is not more than 50 m/min.
⑤ opening the sleeve valve under the check valve at the inlet end of KZ65-25 valve, closing the connecting valve between the check valve and the underground oil pipe, opening the outlet valve of the oil pipe at the outlet end of the other side, closing the outlet valve of the sleeve pipe at the same side, and starting the nitrogen making vehicle to make gas lift after the inlet and outlet flow of the well head valve is completed.
⑥ conveying nitrogen to the annular space of oil jacket by nitrogen making vehicle, wherein the nitrogen input amount should be controlled at 23.0m during construction3/h-24.0m3H, and the wellhead pressure increase must not exceed 0.5MPa, and the outlet discharge is observed.
⑦ after the gas lift is started for 20min, the visual logging instrument is slowly lowered to start observing the well wall, and the lowering speed of the visual logging instrument is controlled, wherein the lowering speed is not more than 20 m/min, and the gas lift is kept continuously.
⑧ stop and observe for five minutes at 1362 m, 1367 m, 1372 m, 1377 m, 1382 m and 1387 m, 1908 m, 1912 m, 1916 m, 1924 m, 1926 m and 1928 m respectively, observe water well sections (check whether each perforation section has bubble, water, oil and the like) and analyze the relative position of the leaking point and the stopping point observation point according to the water direction mark, thereby quickly finding the leaking point and excluding the casing section without the leaking point.
⑨ when water or oil is found, the site construction record is made in time, and after the test is finished, the site record and video data are collated and transmitted back to the first party.
⑩ if the visual logging instrument test video is not obvious to observe the water or oil well section at the bottom of the well, the test can be repeated under the condition of negative pressure in the gas lift construction, so as to achieve the purpose that the test video meets the construction design requirement.
After the gas lift is finished, the gas is blown out from the oil pipe and is decompressed from the nitrogen making vehicle, the pipeline cannot be detached under the non-decompression state, the pressure is prevented from hurting people, and the discharged liquid amount and the nitrogen injection amount are accurately measured.
And (5) pulling out the gas lift pipe column, installing a wellhead well completion, and waiting for the next measure.
In the embodiment of the invention, the well-flushing return liquid is completely recycled to the recycling tank, and is filtered and clarified.
After the clarified liquid reaches the standard of reutilization, the clarified liquid is recycled in the next procedure or transported to a subsequent construction well. And (4) pulling and conveying the residual liquid which cannot be recycled to a centralized treatment point for advanced treatment.
The crude oil or formation water produced from the stratum enters a special crude oil metering tank to be collected and transported to a nearby oil extraction operation area, and the oil extraction operation area is responsible for disposal.
FIG. 2 is a photograph of the leak from the town 295-289 well described in the example of the present invention, in which a leak between 1379.882m-1379.907 is visible, and the size and shape of the leak is clearly visible.
In another embodiment of the present invention, a specific construction process for a well 148-03 is provided.
The well is a test well for gas lift negative pressure leakage detection of a Changqing oil and gas institute, 11-day (10 months and 27 days) team finishes assembling at a well site, and comprises 1 liquid nitrogen vehicle, 1 nitrogen pump vehicle, a plurality of logging truck and operating personnel, and the assembling finishes and prepares before measurement. The lower depth of the gas lift pipe column is 760.2m, and the front end of the gas lift pipe column is provided with a bell mouth. And the VideoLog visual logging instrument is lowered from the oil pipe for detection. The initial liquid level is located 25.6m, and near the bellmouth is gone down to the instrument, starts the gas lift, lasts the gas lift and stops the gas lift until the export is not when having well liquid to discharge, and the instrument is transferred at the uniform velocity, observes the damaged condition of wall of a well sleeve pipe, observes water simultaneously and marks monitoring water flow direction, tracks and fixes a position the hourglass water spot. And detecting the well section to be 760m-1460m, and finding a plurality of casing fracture and water outlet points. 6 in the afternoon: and 50, finishing the test and withdrawing the well site.
The test result shows that:
(1) the sleeve openings are opposite in depth, and the sleeve compensation distance is 4.8 m.
(2) Initial liquid level: 25.9 m.
(3) A bell mouth: cable depth 768m, actual depth (762m)
(4)844m-865m, serious casing damage, 846.1m,859.3m and 864.3 m.
(5)1475m reached the bridge plug position (actual depth 1468 m).
Well fluid can be effectively discharged through the gas lift, the pressure balance of the shaft is damaged, negative pressure is formed in the shaft, and a leakage point is discharged; according to the method for finding the leakage of the casing damage well under the well through the visualization of the nitrogen gas lift negative pressure, the balance of the pressure of the shaft is broken, the negative pressure is formed in the casing, so that the leakage point can be drained, the condition that the leakage point is drained is observed through a visualization logging instrument, and the damage point of the casing is found. Meanwhile, the flowing direction of the well fluid is judged by utilizing the water direction indicator, so that the sleeve leakage point can be tracked and positioned more efficiently. After the detection judgment, 836m-857m is found, the sleeve damage is serious, 838.1m, 851.3m and 856.3m confirm the water outlet points of three sleeve breakages. The history of the whole leakage finding construction process is less than 6 hours, the leakage finding construction time for the damaged sleeve in the prior art is greatly shortened, and the positions and the image information of three leakage points are accurately found.
In conclusion, the gas lift is a precondition and a basis for finding leakage, and the structure, the running depth and the gas lift pressure of a gas lift pipe column are reasonably set to ensure safe gas lift; the logging instrument lens of the visual logging instrument must have a self-cleaning function to prevent oil stains from adhering to and blocking light and sight.
While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (10)
1. A method for detecting leakage of a casing damage well under well by using nitrogen gas lift negative pressure visualization is characterized in that: comprises the following steps of (a) carrying out,
drifting and scraping by using a drift size gauge;
plugging the perforation section;
after well flushing, putting a pipe column down for pressure test to ensure bridge plug setting;
sealing the well mouth;
lowering a gas-lift pipe column, and lowering a visual logging instrument in the gas-lift pipe column until the visual logging instrument extends out of a bell mouth of the gas-lift pipe column;
introducing nitrogen into an annular space between the gas lift pipe column and the sleeve for gas lift, and observing the liquid discharge condition of an outlet;
after negative pressure is formed between the casing and the stratum, the visual logging instrument is continuously and slowly lowered; the method comprises the steps of transmitting image information according to a visual logging instrument, directly observing the casing wall condition, and recording and feeding back the water or oil outlet position of a casing and related information; the water or oil outlet position of the sleeve is the damaged position.
2. The method for visually finding leakage of a casing damage well under a nitrogen gas lift negative pressure as claimed in claim 1, wherein: the method specifically comprises the following steps of (1) pulling out a raw well pipe column; (2) drifting and scraping by using a drift size gauge; (3) drilling a bridge plug to plug the perforation section; (4) a well washing pipe column is lowered to wash the well until the water quality in and out is close; (5) installing a KZ65-25 wellhead device, and testing the pressure test of the wellhead to detect the sealing condition; (6) one end of a valve inlet check valve of the KZ65-25 wellhead device is connected with a nitrogen making vehicle pipeline, the outlet of the other end of the valve inlet check valve is connected with a liquid storage tank, the outlet of an oil pipe valve is connected with the liquid storage tank through an oil pipe, and pressure testing is carried out after the wellhead pipeline is connected; (7) installing a wellhead lubricator; (8) lowering the gas-lift pipe column, and then lowering the visual logging instrument from the gas-lift pipe column until the visual logging instrument extends out of the bell mouth of the gas-lift pipe column; (9) opening a valve, starting a nitrogen making vehicle, introducing nitrogen into an annular space between a gas lift pipe column and a sleeve for gas lift, and observing the liquid discharge condition of a liquid discharge port of the gas lift pipe column; (10) after the gas lift is carried out for 5-40min, continuously and slowly lowering the visual logging instrument under the condition of keeping the gas lift, and observing the casing wall; the method comprises the steps of transmitting image information according to a visual logging instrument, directly observing the casing wall condition, and recording and feeding back the water or oil outlet position of a casing and related information; (11) the water or oil outlet position of the sleeve is the leakage point position.
3. The method for visually finding leakage of a casing damage well under a nitrogen gas lift negative pressure as claimed in claim 2, wherein: in the step (5), the pressure of the seal test is 10MPa, and the pressure drop is less than 0.5MPa in 5 minutes of the test.
4. The method for visually finding leakage of a casing damage well under a nitrogen gas lift negative pressure as claimed in claim 2, wherein: and (6) drilling an earth anchor on an oil pipe connecting the outlet of the oil pipe valve and the liquid storage tank.
5. The method for visually finding leakage of a casing damage well under a nitrogen gas lift negative pressure as claimed in claim 2, wherein: the well flushing discharge capacity of the running water in the step (4) is 400-800L/min.
6. The method for visually finding leakage of a casing damage well under a nitrogen gas lift negative pressure as claimed in claim 2, wherein: and (4) lowering the visual logging instrument in the step (8) at a speed of less than 50 m/min.
7. The method for visual leakage detection of the casing damage well downhole nitrogen gas lift negative pressure as claimed in any one of claims 1 to 6, wherein: in the process of lowering the visual logging instrument to observe the casing wall, a stop point observation method is adopted, the stop point distance is 1-10 meters, and the stop point time is 1-10 minutes.
8. The method for visual leakage detection of the casing damage well downhole nitrogen gas lift negative pressure as claimed in claim 7, wherein: during the observation process of a stop point through a visual logging instrument, judging the direction of water flow through a water direction marker on the visual logging instrument, and judging the relative position of a leakage point and an observation point according to the direction of the water flow; the well fluid flows upwards, and the leakage point is below; turbulent flow occurs in well fluid, and a water outlet point is arranged nearby; the well fluid has no fluidity, and a water outlet point is not arranged below the well fluid; the water drifts transversely to the mark and/or the water quality suddenly becomes better in transmittance, and a leakage point is arranged nearby.
9. The method for visually finding leakage of a casing damage well by using nitrogen gas lift negative pressure in the well according to claim 8, wherein the method comprises the following steps: the visual logging instrument is a self-cleaning lens visual logging instrument.
10. The method for visually finding leakage of a casing damage well by using nitrogen gas lift negative pressure in a well according to claim 9, wherein the method comprises the following steps: the visual logging instrument is a self-cleaning light source visual logging instrument.
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