CN114718502B - Abandoned well plugging method - Google Patents
Abandoned well plugging method Download PDFInfo
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- CN114718502B CN114718502B CN202110005512.7A CN202110005512A CN114718502B CN 114718502 B CN114718502 B CN 114718502B CN 202110005512 A CN202110005512 A CN 202110005512A CN 114718502 B CN114718502 B CN 114718502B
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- 238000000034 method Methods 0.000 title claims abstract description 60
- 238000002347 injection Methods 0.000 claims abstract description 122
- 239000007924 injection Substances 0.000 claims abstract description 122
- 239000004568 cement Substances 0.000 claims abstract description 107
- 239000007788 liquid Substances 0.000 claims abstract description 43
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 41
- 239000012530 fluid Substances 0.000 claims description 24
- 238000005086 pumping Methods 0.000 claims description 18
- 238000013461 design Methods 0.000 claims description 11
- 230000015572 biosynthetic process Effects 0.000 claims description 8
- 230000009471 action Effects 0.000 claims description 7
- 230000000903 blocking effect Effects 0.000 claims description 7
- 238000011010 flushing procedure Methods 0.000 claims description 7
- 238000012360 testing method Methods 0.000 claims description 7
- 125000006850 spacer group Chemical group 0.000 claims description 6
- 238000005406 washing Methods 0.000 claims description 5
- 239000002245 particle Substances 0.000 claims description 4
- 239000002699 waste material Substances 0.000 claims 2
- 238000005266 casting Methods 0.000 claims 1
- 230000015271 coagulation Effects 0.000 claims 1
- 238000005345 coagulation Methods 0.000 claims 1
- 239000002002 slurry Substances 0.000 abstract description 26
- 239000007789 gas Substances 0.000 description 22
- 239000003245 coal Substances 0.000 description 12
- 230000008569 process Effects 0.000 description 12
- 238000007789 sealing Methods 0.000 description 7
- 239000011083 cement mortar Substances 0.000 description 6
- 239000000084 colloidal system Substances 0.000 description 4
- 238000007711 solidification Methods 0.000 description 3
- 230000008023 solidification Effects 0.000 description 3
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 2
- 239000000460 chlorine Substances 0.000 description 2
- 229910052801 chlorine Inorganic materials 0.000 description 2
- 238000010276 construction Methods 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005553 drilling Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009933 burial Methods 0.000 description 1
- 229910052918 calcium silicate Inorganic materials 0.000 description 1
- 239000000378 calcium silicate Substances 0.000 description 1
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000007872 degassing Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 238000001802 infusion Methods 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B33/00—Sealing or packing boreholes or wells
- E21B33/10—Sealing or packing boreholes or wells in the borehole
- E21B33/13—Methods or devices for cementing, for plugging holes, crevices or the like
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- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The application discloses a method for plugging an abandoned well, which comprises the following steps: a cement injection pipe column is put into the target abandoned well; injecting well-killing liquid into the ash injection pipe column, and throwing into a plugging ball, wherein the plugging ball is used for plugging perforation holes of a target abandoned well; after the plugging balls plug all perforation holes, cement slurry is injected into the cement injection pipe column, and the target abandoned well is plugged. The method for plugging the abandoned well can improve the plugging quality and the plugging success rate of the abandoned well.
Description
Technical Field
The application relates to the technical field of oil and gas field exploration and development, in particular to a method for plugging an abandoned well.
Background
The abandoned well is an inevitable product in the exploration and development process of the oil and gas field, and if the abandoned well is not perfectly disposed, the risks of out-of-control accidents, oil and gas leakage, water source pollution and the like exist. Currently, the United states and Canada have set forth relevant legal requirements for plugging of oil and gas abandoned wells, china also promulgates guidelines for disposal of abandoned wells and long stop wells (SY/T6646-2006) and regulations for disposal of abandoned well sealing (Q/SH 0653-2015), and sets forth plugging standards for oil and gas abandoned wells.
However, coal bed gas abandoned wells differ from conventional oil and gas abandoned wells in that they have the following characteristics: (1) The main reason for discarding the coalbed methane well is that the process level is low, and temporary well sealing is mainly carried out; (2) The coal bed is produced without water injection, so that the stratum pressure is low, and the coal bed deficiency is serious; (3) The coal bed gas well has fracturing transformation process, and a large number of cracks are easy to cause plugging leakage.
Therefore, the plugging process of the conventional oil gas abandoned well has poor applicability to the coal bed gas abandoned well and has low plugging success rate.
Disclosure of Invention
In view of the above, the application provides a method for plugging an abandoned well, which can improve the plugging quality and the plugging success rate of the abandoned well.
The application adopts the following technical scheme:
a method of plugging a abandoned well, the method comprising:
a cement injection pipe column is put into the target abandoned well;
injecting well-killing liquid into the ash injection pipe column, and throwing in a plugging ball, wherein the plugging ball is used for plugging perforation holes of the target abandoned well;
and after the plugging balls plug all the perforation holes, cement slurry is injected into the ash injection pipe column, so that the target abandoned well is plugged.
As a preferred embodiment, the injecting the well control fluid into the ash injection string and the injecting the plugging ball include:
connecting the ash injection pipe column with an injection pipeline and a ball injection pipeline, wherein the injection pipeline is used for conveying liquid media, and the ball injection pipeline is used for conveying plugging balls;
and connecting the liquid injection pipeline and the ball injection pipeline, conveying well control liquid mixed with the plugging balls into the target abandoned well through the ash injection pipe column, and plugging perforation holes on the target abandoned well wall by the plugging balls under the pressure action of the well control liquid.
As a preferred embodiment, before said connecting the liquid injection pipe and the ball feeding pipe, the method further comprises:
and the liquid inlet and outlet of the positive circulation well flushing to the target abandoned well are consistent.
As a preferred embodiment, after the connecting the liquid injection pipe and the ball injection pipe and the transporting the well control fluid mixed with the plugging ball into the target abandoned well through the ash injection pipe column, the method further comprises:
obtaining a pumping pressure of pumping well control fluid into the ash injection pipe column, and determining that the plugging balls plug all perforation holes when the pumping pressure meets a preset condition, wherein the preset condition is that the pumping pressure is greater than a set pressure and/or the pumping speed is greater than a set speed, and the set pressure is greater than the formation pressure of the target abandoned well;
lifting the ash injection pipe column to enable the lower end of the ash injection pipe column to be located at the lower boundary position of a cement plug to be formed.
As a preferred embodiment, the injecting cement slurry into the ash injection pipe column to plug the target abandoned well comprises:
sequentially injecting front spacer fluid, cement paste, rear spacer fluid and replacement fluid into the ash injection pipe column according to the designed dosage;
replacing the cement paste to a design position, wherein the design position is the position of a cement plug to be formed;
after the inside and outside of the ash injection pipe column are in a balanced state, lifting the ash injection pipe column to the position above the design position;
and (5) reversely circulating to wash the well and wash out redundant cement paste.
As a preferred embodiment, the reverse circulation well-flushing, after flushing out the excess cement slurry, the method further comprises:
lifting the ash injection pipe column to a safe position;
and (5) setting a wellhead, closing the well, waiting for solidification, and forming the cement plug in the target abandoned well.
As a preferred embodiment, the method further comprises:
and drilling through the cement plug when the target abandoned well needs to be reused.
As a preferred embodiment, before the step of lowering the ash injection string into the target abandoned well, the method further comprises:
and (3) pigging, and carrying out pressure test on the sleeve and the ash injection pipe column.
As a preferred embodiment, the density of the plugging balls is 0.85-0.95 g/m 3 ；
The particle size of the plugging ball is 1.3-1.5 times of the diameter of the perforation.
As a preferred embodiment, the number of the plugging balls is 2-3 times the number of the perforation holes.
The beneficial effects of this application embodiment lie in at least:
according to the method for plugging the abandoned well, plugging and plugging of the abandoned well are achieved, when the method is implemented, well control liquid and a plugging ball are poured into the target abandoned well, and perforation holes on a well wall are plugged by the plugging ball, so that the plugging of the target abandoned well is completed. And then, implementing an ash injection process, injecting cement slurry into the target abandoned well after plugging, wherein the cement slurry can form a cement plug in the target abandoned well, so that the target abandoned well is plugged. Therefore, the method has the advantages that the abandoned well is plugged firstly and then plugged, the plugging quality and the plugging success rate are greatly improved, the operation process is simple, and excessive cost is not required.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for plugging a abandoned well provided in an embodiment of the present application;
FIG. 2 is a flow chart of another method for plugging a abandoned well provided in an embodiment of the present application;
FIG. 3 is a flow chart of an ash injection method provided in an embodiment of the present application;
FIG. 4 is a schematic illustration of a situation in a plugged target abandoned well according to an embodiment of the present disclosure;
fig. 5 is a schematic diagram of a situation in a target abandoned well after formation of a suspended cement plug according to an embodiment of the present application.
Reference numerals denote:
1. an ash injection pipe column;
2. a blocking ball;
3. a sleeve;
4. suspending the cement plug;
5. perforating;
6. a watch case;
7. a coal seam;
8. a rock formation;
9. and (5) manually setting the well bottom.
Specific embodiments thereof have been shown by way of example in the drawings and will herein be described in more detail. These drawings and the written description are not intended to limit the scope of the inventive concepts in any way, but to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments.
Detailed Description
The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.
The embodiment of the application provides a method for plugging an abandoned well, which can be applied to a conventional oil gas abandoned well and a coal bed gas abandoned well, and has wider applicability.
As shown in fig. 1, the method for plugging a abandoned well provided in the embodiment of the present application includes the following steps:
step 101, setting an ash injection pipe column into a target abandoned well;
102, injecting well-killing liquid into an ash injection tubular column, and throwing in a plugging ball, wherein the plugging ball is used for plugging perforation holes of a target abandoned well;
and 103, after the plugging balls plug all the perforation holes, cement slurry is injected into the cement injection pipe column, and the target abandoned well is plugged.
According to the method for plugging the abandoned well, plugging and plugging of the abandoned well are achieved, when the method is implemented, well control liquid and a plugging ball are poured into the target abandoned well, and perforation holes on a well wall are plugged by the plugging ball, so that the plugging of the target abandoned well is completed. And then, implementing an ash injection process, injecting cement slurry into the target abandoned well after plugging, wherein the cement slurry can form a cement plug in the target abandoned well, so that the target abandoned well is plugged. Therefore, the method has the advantages that the abandoned well is plugged firstly and then plugged, the plugging quality and the plugging success rate are greatly improved, the operation process is simple, and excessive cost is not required.
For convenience of description, a method for plugging a abandoned well according to the embodiments of the present application is further described and illustrated below with reference to fig. 2 to 5.
As shown in fig. 2, the embodiment of the application provides a method for plugging a abandoned well, which can be suitable for an oil-gas well or a coal-bed gas well with a large number of cracks and serious leakage, and can include steps 201 to 209.
Step 201, pigging, and pressure testing the sleeve and the ash injection pipe column.
The purpose of the open well is to prevent the casing from reducing and the tool from reaching the designed position.
In some embodiments of the present application, a tool or a wiper may be used to clear a target abandoned well in accordance with well-clearance procedures. Wherein, the drift size gauge or the scraper is matched with the casing, and the drift is carried out according to the design depth.
The well completion of the sleeve and the ash injection pipe column is a key condition for blocking and stopping, once the sleeve and the ash injection pipe column are in a problem, engineering accidents of the pipe clamping column are easy to cause, and even the oil-water well or the coal bed gas well is scrapped under serious conditions. Therefore, the casing and the ash injection string need to be tested for pressure before the target abandoned well is plugged.
Taking pressure test of the ash injection pipe column as an example, two ends of the ash injection pipe column can be sealed first, then water is injected into the ash injection pipe column, and whether leakage occurs on a pipeline is checked after the water is fully injected; the two ends of the ash injection pipe column are respectively provided with a pressure gauge, the pressure values measured by the two pressure gauges are read after the ash injection pipe column is filled with water, if the readings of the two pressure gauges are consistent, the ash injection pipe column is free from leakage, and if the readings are inconsistent, the ash injection pipe column is leaked, and maintenance is needed or a packer is put into for protection.
And 202, setting an ash injection pipe column into the target abandoned well.
And when no leakage is determined after the pressure test of the ash injection pipe column, the ash injection pipe column is lowered into the target abandoned well, wherein the lower end of the ash injection pipe column is positioned below a cement plug to be formed, and the position of the cement plug can be obtained through the prior calculation and design.
And 203, performing positive circulation well flushing until the inlet and outlet fluids of the target abandoned well are consistent.
The well flushing is used for degassing and cooling, and can also detect whether the circulation system works normally.
Illustratively, the circulation system may include a fluid line, a fluid discharge line, and two pump trucks having fluid pumps disposed thereon for providing a driving force when delivering the fluid medium. One of the two pump vehicles is connected with a transfusion tube, and the transfusion tube is communicated with an ash injection pipeline; another pump truck is connected to a drain, the inlet of which is located in the well for carrying the substances (liquid, solid, gas) in the well to the surface, thereby changing the liquid properties in the well.
When the well is washed, the well is washed by utilizing the large-displacement positive circulation of the well washing liquid, and the property of the liquid at the outlet of the liquid discharge pipe is detected, and when the property of the liquid at the outlet of the liquid discharge pipe is consistent with the property of the well washing liquid injected by the input pipe, the well washing is finished. In some embodiments of the present application, the well-flushing fluid may be clear water. The infusion tube may be a water injection tube at this point.
Step 204, connecting the ash injection pipe column with the liquid injection pipeline and the ball injection pipeline.
In some embodiments of the present application, the bowler may also be deployed in the field. The pump truck is connected with the liquid injection pipeline, the ball injection truck is connected with the ball injection pipeline, and the liquid injection pipeline, the ball injection pipeline and the ash injection pipe column are connected through a tee joint. The liquid injection pipeline is used for conveying liquid medium, such as well control liquid, and the ball injection pipeline is used for conveying the plugging balls. Illustratively, the kill fluid injected into the target abandoned well may be clear water.
Valves can be respectively arranged on the liquid injection pipeline and the ball injection pipeline, and when the valves are opened, the pipeline is communicated, so that a medium can be conveyed; when the valve is closed, the pipeline is cut off, and the medium is stopped being conveyed. Of course, the pipeline is not provided with a valve, and the on-off of the pipeline is controlled only by the working states of the pump truck and the ball throwing truck.
When the abandoned well with a large number of cracks and serious leakage is plugged, if the abandoned well is plugged by direct ash injection, the plugging failure is easily caused by poor sealing performance, so that the abandoned well needs to be plugged by steps 205-206.
And 205, connecting a liquid injection pipeline and a ball injection pipeline, and conveying the well control liquid mixed with the plugging balls into the target abandoned well through the ash injection pipe column.
In some embodiments of the application, the outlet of the liquid discharge pipe and the inlet of the liquid injection pipe can be placed in the clean water storage pool, and clean water can circularly flow in the target abandoned well under the drive of the liquid pump, so that the construction cost is saved. And when the clear water circularly flows, the ball throwing pipeline is connected to throw the plugging balls into the target abandoned well, so that the plugging balls can plug perforation holes in the well under the action of water pressure. The height of the clear water in the target abandoned well is higher than that of the perforation holes, so that all the perforation holes can be completely plugged by the plugging balls floating in the clear water to form a plugging layer.
If the density of the plugging balls is too high, the plugging balls can sink into the water bottom, and the control is difficult; if the density of the plugging balls is too small, the plugging balls are easy to float on the water surface all the time, and can not plug perforation holes, so that the density interval is selected to be 0.85-0.95 kg/m 3 So that the plugging ball can suspend in water and plug the perforation holes along the water flow direction.
Further, a plugging ball with a grain diameter which is 1.3 to 1.5 times of the diameter of the perforation holes can be adopted, so that even if the shape of the perforation holes is irregular, the plugging ball can have good plugging effect.
In order to ensure that the plugging balls put into the water sufficiently plug all the perforation holes, the number of the plugging balls is set to be 2-3 times of the number of the perforation holes in the process of throwing the plugging balls, namely, the number of the plugging balls is 2-3 times of the number of the perforation holes, so that even if a part of the plugging balls suspend, the plugging balls can sufficiently plug the perforation holes.
In the embodiments of the present application, the compressive strength of the plugging ball may be 15 to 20MPa, for example.
And 206, acquiring a pumping pressure of pumping well control fluid into the ash injection pipe column, and determining the plugging balls to plug all perforation holes when the pumping pressure meets the preset condition.
When the pump truck pumps clear water and the plugging balls into the ash injection pipe column, the well environment is an open environment due to the existence of perforation holes in the target abandoned well, the obtained pump pressure for pumping clear water into the ash injection pipe column is low, and the pump pressure is slow in speed increasing or even no speed increasing.
Along with the gradual plugging of the perforation holes by the plugging balls, the well environment gradually changes into a semi-open environment, the pumping pressure of the obtained clean water pumped into the ash injection pipe column is still lower or slightly improved, and the pumping speed is still slower.
After the plugging balls plug all perforation holes, the environment in the well is changed into a closed environment, the pumping pressure of the obtained clean water pumped into the ash injection pipe column is obviously improved, and the pumping speed is obviously increased. Therefore, the preset condition is set based on the principle, and when the pump pressure is detected to meet the preset condition, the plugging ball can be determined to plug all the perforation holes. Accordingly, the preset condition may be that the pump pressure is greater than a set pressure and/or that the pump pressure is increased greater than a set velocity, wherein the set pressure is greater than the formation pressure.
In embodiments of the present application, the pump pressure may be obtained by a pressure gauge or other load cell.
After completion of step 206, this means that the lost circulation work for the target abandoned well has been completed. FIG. 4 shows a schematic diagram of the situation in a target abandoned well after plugging. As shown in fig. 4, the plugging ball 2 entering the well from the upper end of the ash injection pipe column 1 leaves the interior of the ash injection pipe column 1 at the lower end of the ash injection pipe column 1 along with the circulating flow of the well control fluid, and then tightly abuts against the positions where the cracks and the perforation holes exist on the sleeve 3 under the action of hydraulic pressure, so that the plugging of the cracks and the perforation holes is realized, and the plugging work of the target abandoned well is completed.
It should be noted that the plugging ball is a temporary plugging for cracks and perforation holes, and may be separated from the cracks and perforation holes when the formation pressure is greater than the well internal pressure as the hydraulic pressure in the target waste gas well is reduced.
Therefore, after plugging is completed, the target abandoned well is required to be subjected to ash injection plugging, and the ash injection plugging is a firmer plugging method, so that the target abandoned well can be permanently plugged under the condition of being not damaged.
Step 207, lifting up the ash injection pipe column, and enabling the lower end of the ash injection pipe column to be located at the lower boundary position of the cement plug to be formed.
After the plugging ball plugs the perforation holes, the ash injection pipe column is required to be lifted up, so that the lower end of the ash injection pipe column is positioned at the lower boundary position of the cement plug to be formed, the lower boundary position of the cement plug to be formed is higher than the plugging layer position of the plugging ball, and the formed cement plug can be positioned above the plugging layer position of the plugging ball. The cement plug to be formed can be a suspended cement plug. For example, for a coal-bed gas well, the upper elevation of the injection string may range from 5 to 20m, i.e., the distance between the lower end of the injection string and the uppermost portion of the plugging horizon is from 5 to 20m.
And step 208, cement slurry is injected into the ash injection pipe column, and the target abandoned well is plugged.
The technological principle of injecting cement slurry to plug the target abandoned well is as follows:
after the cement is mixed with proper amount of water to form cement slurry, the cement particles and water are hydrated immediately to produce colloid with calcium silicate as main component in the cement slurry, and the colloid is increased and concentrated gradually to become thick. Meanwhile, new compounds forming cement stones are generated in the colloid, and the cement paste gradually starts to show particle crystals in the amorphous colloid and gradually hardens, so that the cement paste loses fluidity. In this process, when the cement slurry begins to thicken and partially lose plasticity, it is called initial setting; when the cement slurry has lost fluidity completely and is just able to bear a certain pressure, it is called final setting. And after finishing the final setting, the cement paste is hardened into stones, so that the plugging of the target abandoned well is realized.
Illustratively, the cement slurry may be formulated by:
step 301, calculating the actual consumption of the cement slurry according to the theoretical consumption of the cement slurry.
In the examples of the present application, the theoretical amount V of cement paste Management device The calculation can be performed using the following formula:
V management device =the internal volume per meter of the sleeve of the injection section x the estimated cement plug thickness.
In general, the actual amount V of cement paste Real world Is the theoretical dosage V Management device 1.2 to 2.0 times, but in special cases, the actual amount V Real world There may be more, which needs to be determined according to the actual situation.
Step 302, calculating the dosage of the dry cement and the ash water based on the actual dosage of the cement slurry.
In the examples herein, the amount of dry cement may be calculated using the following formula:
wherein G is 1 The dosage of the cement is t; v (V) Real world M is the actual dosage of cement paste 3 ；ρ 1 Density of dry cement, g/cm 3 ；ρ 2 To density of the ash water, g/cm 3 ；ρ 3 Is the density of cement paste, g/cm 3 。
The dosage of the ash water can be calculated by adopting the following formula:
G 2 ＝ρ 3 V real world -G 1
Wherein G is 2 The dosage of the ash water is t.
In some embodiments, the ash water may be clean water, wherein prior to use, a chlorine test is required on the clean water, which may be used to ash when the chlorine content is less than 500 mg/L.
Step 303, adding the cement-mixing water and the dry cement into the cement-mixing tank to prepare cement slurry.
When the cement mortar is prepared, the cement mortar can be added into the cement mortar preparing tank, then the stirring device is started, and dry cement is added into the cement mortar preparing tank while stirring, so that the cement mortar and the dry cement are fully and uniformly mixed, and the prepared cement mortar is obtained.
Depending on the pressure in the well and the construction process, the method of cementing the plug may include a pour-in cementing plug, a circulation-in cementing plug, an squeeze-in cementing plug (including circulation + squeeze), a cable/rope ash dumping method, and the like. The following will further describe an example of a cyclic cementing plug.
Specifically, as shown in fig. 3, in some implementations of the embodiments of the present application, the method for plugging the target abandoned well by injecting cement slurry into the ash injection string in a circulating manner may include the following steps:
and 401, sequentially injecting the front spacer fluid, the cement paste, the rear spacer fluid and the replacement fluid into the ash injection pipe column according to the designed dosage.
Step 402, replacing cement paste to a design position.
The design position is the position of the cement plug to be formed.
Step 403, lifting the ash injection pipe column to the position above the design position after the inside and outside of the ash injection pipe column are in a balanced state.
Illustratively, the injection string can be raised to a position 1-3m above the expected ash face (i.e., the cement plug interface).
Step 404, reverse circulation well washing is performed to wash out redundant cement paste.
Step 405, lifting the ash injection string to a safe position.
For example, the injection string may be lifted to a position 100m above the expected ash surface, and if there is an open interval above the expected ash surface, the string should be lifted above the top boundary of the open interval.
And 406, setting a wellhead, closing the well, waiting for solidification, and forming a cement plug in the target abandoned well.
Illustratively, the wellhead may be set with an elevator or with a casing head. After the wellhead is installed, the well bore is filled with well-killing liquid, and then the well is closed for waiting for solidification. Care is taken to observe the wellhead during waiting for condensation.
In some embodiments of the present application, step 406 specifically further includes:
step 4061, detecting the position (depth) of the cement surface after waiting for the preset time;
step 4062, checking the sealing condition of the cement plug according to standard pressure test, wherein the pressure test method can be selected according to different well conditions.
Illustratively, the ash face may be tested for 10-15 MPa, and if the pressure drop is less than 0.5MPa within 30 minutes, then the cement plug seal is determined to be successful.
After the cement plug is formed in the target abandoned well, the permanent plugging work of the target abandoned well is completed, and the cement plug is a suspended cement plug.
Fig. 5 shows a schematic view of the situation in the target disposal well after formation of a suspended cement plug. As shown in fig. 5, after the cement paste in the target abandoned well is coagulated, a suspended cement plug 4 is formed in the well, the suspended cement plug 4 and the target abandoned well are firmly combined together, permanent plugging of the target abandoned well is achieved, and the plugging ball 2 is located below the suspended cement plug 4. Illustratively, the thickness of the suspended cement plug may be 10-20m.
If the target abandoned well needs to be reused in subsequent operations, step 209 may be performed.
Step 209, drilling through the cement plug when the target abandoned well needs to be reused.
After the suspended cement plug is formed, the target abandoned well is in a well sealing state, the upper end and the lower end of the suspended cement plug are mutually isolated, and the lower end of the suspended cement plug in the shaft is filled with clean water. When the target abandoned well needs to be reused, the suspended cement plug can be drilled through, the well sealing state is released, and the target abandoned well is continuously utilized.
After the suspended cement plug is drilled through, clear water in the well can be pumped out in a reverse circulation mode, so that the water pressure in the well is reduced, and when the water pressure is reduced to be smaller than the stratum pressure, the plugging ball can be naturally separated from the perforation holes under the action of the stratum pressure. Compared with the mode of directly plugging the perforation holes by cement slurry in the related art, the method can avoid secondary damage to the reservoir, reduce secondary pollution of the reservoir and greatly reduce the operation cost.
In summary, by adopting the method for plugging the abandoned well provided by the embodiment of the application, when the target abandoned well is plugged, the well-killing liquid and the plugging balls are poured into the target abandoned well, the plugging balls are attached to the cracks and the perforation holes under the pressure of the well-killing liquid, the cracks and the perforation holes are firmly plugged, the communication between the space in the well and the stratum space is blocked, and a relatively airtight environment is formed in the well, so that the plugging work of the target abandoned well is completed.
After the plugging balls are used for plugging the cracks and the perforation holes, cement slurry is injected into the well, the cement slurry can form a cement plug in the well, the formed cement plug is firmly and tightly connected with the well wall or the inner wall of the casing, the better connection strength and the sealing effect are achieved, the target abandoned well can be further plugged, and the plugging is permanent under the condition that the cement plug is not damaged.
Therefore, compared with the related art, the abandoned well plugging method provided by the embodiment of the application adopts the inventive concept of plugging firstly and then plugging, has simple operation process, and can greatly improve the plugging quality and the plugging success rate.
In the related art, perforation holes in a target abandoned well are usually plugged directly by cement slurry, when the abandoned well needs to be reused, explosion perforation needs to be performed again, so that a well hole is opened, but secondary damage is caused to a reservoir, and the yield of an oil-gas field is affected.
In the method for plugging the abandoned well, provided by the embodiment of the application, temporary plugging and permanent plugging are combined, and for the situation of permanently plugging the abandoned well, no management is needed after the cement plug is formed; in the case of temporarily plugging the abandoned well, if the abandoned well is to be reused later, the cement plug only needs to be drilled through. Compared with the method for directly plugging the holes by cement slurry in the related art, the plugging balls and the holes are not firmly connected, so that secondary damage to the reservoir is avoided, and the operation cost is greatly reduced.
In addition, the plugging method for the abandoned well can be suitable for coal beds with different coal grades, burial depths and formation temperatures, can be suitable for the situation that the conventional oil gas abandoned well and the coal bed gas abandoned well sleeve are good (without dislocation, leakage and the like), can also be suitable for the situation that the conventional oil gas abandoned well and the coal bed gas abandoned well sleeve are seriously lost, and has wider applicability.
Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the present application disclosed herein. This application is intended to cover any variations, uses, or adaptations of the application following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the application pertains. The specification and examples are to be regarded in an illustrative manner only.
It is to be understood that the present application is not limited to the precise arrangements and instrumentalities shown in the drawings, which have been described above, and that various modifications and changes may be effected without departing from the scope thereof. The scope of the application is limited only by the appended claims.
Claims (7)
1. A method for plugging a abandoned well, the method comprising:
a cement injection pipe column is put into the target abandoned well;
injecting well-killing liquid into the ash injection pipe column, and throwing into a blocking ball, wherein the blocking ball is used for blocking perforation holes in the target abandoned well under the pressure action of the well-killing liquid, and the well-killing liquid is clean water;
after the plugging balls plug all the perforation holes, lifting the ash injection pipe column to enable the lower end of the ash injection pipe column to be positioned at the lower boundary position of a cement plug to be formed;
sequentially injecting front spacer fluid, cement paste, rear spacer fluid and replacement fluid into the ash injection pipe column according to the designed dosage;
replacing the cement paste to a design position, wherein the design position is the position of the cement plug to be formed;
after the inside and outside of the ash injection pipe column are in a balanced state, lifting the ash injection pipe column to the position above the design position;
reverse circulation well washing is carried out to wash out redundant cement paste;
lifting the ash injection pipe column to a safe position;
setting a wellhead, closing the well and waiting for coagulation until the cement plug is formed in the target abandoned well, wherein the cement plug is a suspended cement plug and is positioned above a blocking layer where the blocking ball is positioned;
when the target abandoned well needs to be reused, the suspended cement plug is drilled through, clear water in the well is reversely circulated and pumped out, so that the water pressure in the well is reduced to be smaller than the stratum pressure, and the plugging balls are separated from the perforation holes under the action of the stratum pressure.
2. The method for plugging a abandoned well according to claim 1, wherein the step of injecting the well control fluid into the ash injection string and injecting the plugging balls comprises:
connecting the ash injection pipe column with an injection pipeline and a ball injection pipeline, wherein the injection pipeline is used for conveying liquid media, and the ball injection pipeline is used for conveying plugging balls;
and connecting the liquid injection pipeline and the ball injection pipeline, conveying well control liquid mixed with the plugging balls into the target abandoned well through the ash injection pipe column, and plugging perforation holes in the target abandoned well by the plugging balls under the pressure action of the well control liquid.
3. The method of plugging a abandoned well of claim 2, wherein prior to said connecting the injection conduit and the ball-casting conduit, the method further comprises:
and the liquid inlet and outlet of the positive circulation well flushing to the target abandoned well are consistent.
4. The method of plugging a disposal well according to claim 2, wherein after said connecting said injection pipe and said ball injection pipe and said transporting said well control fluid mixed with said plugging ball into said target disposal well through said injection string, said method further comprises:
obtaining a pumping pressure of pumping the well control fluid into the ash injection pipe column, and determining that the plugging balls plug all the perforation holes when the pumping pressure meets a preset condition, wherein the preset condition is that the pumping pressure is greater than a set pressure and/or the pumping speed is greater than a set speed, and the set pressure is greater than the formation pressure of the target abandoned well;
lifting the ash injection pipe column to enable the lower end of the ash injection pipe column to be located at the lower boundary position of a cement plug to be formed.
5. The method of plugging a waste well of claim 1, wherein prior to running the ash string into the target waste well, the method further comprises:
and (3) pigging, and carrying out pressure test on the sleeve and the ash injection pipe column.
6. The method for plugging a abandoned well according to any one of claims 1 to 5, wherein,
the density of the plugging ball is 0.85-0.95 g/m 3 ；
The particle size of the plugging ball is 1.3-1.5 times of the diameter of the perforation.
7. The method for plugging a abandoned well according to claim 6, wherein the number of the plugging balls is 2 to 3 times the number of the perforation holes.
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| CN118622231A (en) * | 2024-06-05 | 2024-09-10 | 绍兴远西能源科技有限公司 | A method and system for obtaining geothermal resources from depleted fracturing wells |
| CN118481581B (en) * | 2024-06-19 | 2024-11-12 | 中国科学院西北生态环境资源研究院 | A method for biological sealing of abandoned oil field wells capable of reducing greenhouse gases in abandoned oil field wells |
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| CN1070937A (en) * | 1992-11-04 | 1993-04-14 | 大庆石油学院 | Oil well blasthole resin ball plugging agent and its preparation method |
| CN102746837A (en) * | 2012-01-13 | 2012-10-24 | 宫立武 | Microsphere temporary plugging agent for leakage oil well |
| CN103590778A (en) * | 2013-11-12 | 2014-02-19 | 中国地方煤矿总公司 | Method for blocking off waste oil-gas well |
| RU2644360C1 (en) * | 2016-11-08 | 2018-02-09 | Публичное акционерное общество "Татнефть" имени В.Д. Шашина | Installation method of cement bridge in well |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2563236B (en) * | 2017-06-07 | 2020-04-01 | Ardyne Holdings Ltd | Improvements in or relating to well abandonment |
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|---|---|---|---|---|
| CN1070937A (en) * | 1992-11-04 | 1993-04-14 | 大庆石油学院 | Oil well blasthole resin ball plugging agent and its preparation method |
| CN102746837A (en) * | 2012-01-13 | 2012-10-24 | 宫立武 | Microsphere temporary plugging agent for leakage oil well |
| CN103590778A (en) * | 2013-11-12 | 2014-02-19 | 中国地方煤矿总公司 | Method for blocking off waste oil-gas well |
| RU2644360C1 (en) * | 2016-11-08 | 2018-02-09 | Публичное акционерное общество "Татнефть" имени В.Д. Шашина | Installation method of cement bridge in well |
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