Process for abandoning oil and water wells using a wellhead string

Abstract

The present application relates to a kind of with original well pipe column abandoned oil-water well process.Mainly solve the existing abandoned process plugging unreliable, possibly occur interzonal flow phenomenon, need to layer by layer squeeze injection multiple problems.It includes the following steps: judging whether oil-water well condition meets the following conditions simultaneously: ① active pipe column, pipe column has no effective stroke;② oil pipe inner diameter is less than 60mm, or, test resistance;③ test squeeze injection, squeeze injection displacement is not less than 18m3 / h, or, pipe column has no dead mouth and injection volume is not less than design water nozzle flow;Abandoned oil-water well: calculate cement slurry consumption, through oil pipe channel squeeze injection cement slurry, replace squeeze clean water to the oil pipe above wrong break has no cement slurry, pressure holding waiting for condensation, utilize test steel wire to explore pipe inner cement ash surface, cut open the upper oil pipe of ash surface, utilize upper oil pipe to circulate and abandon upper wellbore space.The process can ensure that cement slurry effectively enters each layer, improve plugging effect, without repeated multiple use packer plugging, speed up construction progress.

Description

Technical Field

[0001] This invention relates to the field of oilfield well workover operations, specifically a process for decommissioning oil and water wells using the original well tubing. Background Technology

[0002] With the continuous development of Daqing Oilfield, the underground conditions are becoming increasingly complex. Many oil and water wells are experiencing casing deformation, rupture, and misalignment at different depths. Some wells have multiple instances of casing deformation or misalignment. While various workover techniques can repair a certain number of damaged wells, some wells, due to severe misalignment and large casing displacement, cannot have their lower casing channels opened using existing technologies, resulting in long treatment cycles and high costs. To prevent these wells from interfering with the normal production of surrounding oil and water wells and to meet geological sealing requirements, an effective sealing and treatment technology is urgently needed to address these problems. The original outdated processes, after treating the casing damage points during workover, involved either: firstly, the general injection of cement slurry, but the uneven and uncertain slurry volume at different layers led to unreliable sealing and the potential for layer cross-contamination; secondly, the use of injection packers for injection sealing, but due to the large number of layers, multiple injections were required, increasing labor intensity. Summary of the Invention

[0003] To overcome the shortcomings of existing decommissioning processes, such as unreliability in sealing, potential for layer displacement, and the need for multiple layer-by-layer injections, this invention provides a process for decommissioning oil and water wells using the original well tubing. This process ensures that cement slurry effectively enters each layer, improves the sealing effect, eliminates the need for repeated packer sealing, and speeds up the construction process.

[0004] The technical solution of this invention is: a process for utilizing the original well casing of an abandoned oil or water well, comprising:

[0005] Step 1: Determine if the oil and water well conditions simultaneously meet the following conditions:

[0006] ① The tubing is movable, and the tubing has no effective stroke;

[0007] ② The inner diameter of the oil pipe is less than Ф60mm, or the test is blocked;

[0008] If satisfied, proceed to step two;

[0009] Step 2: Trial injection, with an injection displacement of not less than 18m³. 3 / h, or, there are no dead nozzles in the tubing and the injection volume is not less than the design nozzle flow rate. If the above conditions are met, proceed to step four; otherwise, proceed to step three.

[0010] Step 3: Drill holes in the pipe at the corresponding target layer using a packer or water distributor, and then repeat Step 2.

[0011] Step 4: Abandoning oil and water wells:

[0012] ① Calculate the amount of cement grout needed based on the length of the sealing layer;

[0013] ② Inject cement slurry through the oil pipe channel;

[0014] ③Replace the water with clean water until there is no cement slurry in the oil pipe above the misalignment;

[0015] ④ The pressure must be held for at least 48 hours to allow the mixture to solidify;

[0016] ⑤ Utilize the cement ash surface inside the test wire probe;

[0017] ⑥ Cut open the oil pipe above the gray surface;

[0018] ⑦ Utilize the upper tubing circulation to abandon the upper wellbore space.

[0019] In step one, if the oil and water well conditions do not simultaneously meet conditions ① and ②, then this process is not applicable to the oil and water well.

[0020] In step three, a hole is drilled in the pipe at the corresponding target layer using a packer or distributor, and then a trial injection is performed. If the injection rate is less than 18m³, the injection will be considered successful. 3 If the injection rate is less than the designed nozzle flow rate, or the injection volume is less than the designed nozzle flow rate, then this process is not suitable for the oil-water well.

[0021] In step four, the volume of the injected cement slurry is the sum of the wellbore volume and the volume of the target layer with a sealing radius of 1.5m.

[0022] This invention has the following beneficial effects: Firstly, by adopting the above-mentioned solution, wells with severe casing damage can be abandoned and plugged without major workover, ensuring that cement slurry effectively enters each formation, preventing inter-formation flow, and not interfering with the normal production of surrounding oil and water wells, thus achieving effective abandonment and plugging. Secondly, it solves the problem of repeatedly using packers to plug multi-layer wells, accelerating the construction speed. Attached Figure Description

[0023] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0024] The present invention will be further described below:

[0025] This invention targets conventional vertical wells with relatively consistent downhole fault locations and clear casing damage layers. For these wells containing the original well string, conventional construction methods require heavy-load extraction or back-tangling to remove the original well string above the fault, followed by drilling a channel. Due to the extent of casing damage, some wells lose the lower fault after the string connection is disrupted, making channel drilling or channel retrieval impossible, leading to irreparable damage or ineffective abandonment. Therefore, for wells containing the original well string with multiple active faults, faults concentrated in the open hole section, large fault displacement, and generally unable to open a channel or with lost faults after extraction, this invention can be used for effective abandonment and sealing to ensure effective treatment of such wells containing the original well string.

[0026] Depend on Figure 1 As shown, a process for decommissioning oil and water wells using the original well tubing includes the following steps:

[0027] Step 1: First, determine whether the oil and water well conditions simultaneously meet the following conditions:

[0028] ① The original well tubing string is stuck, the tubing string is movable, and the tubing string has no effective stroke;

[0029] ② For pipe testing, if the inner diameter of the tubing is less than Ф60mm, or if the casing is severely damaged, or if the test is blocked;

[0030] If both conditions ① and ② are met, step two can be continued; if the well conditions of the oil and water well cannot meet conditions ① and ② at the same time, then this process is not applicable to the oil and water well.

[0031] Step 2: Trial injection. If the injection volume is not less than 18m³, 3 / h, or, if during the trial injection it is confirmed that there are no dead nozzles in the tubing and the injection volume is not lower than the design nozzle flow rate, then proceed to step four and abandon the oil and water well;

[0032] For injection displacement less than 18m 3 For wells with a flow rate of / h or no discharge, or an injection volume less than the designed nozzle flow rate, proceed to step three.

[0033] Step 3: For oil and water wells that do not meet the injection conditions in Step 2, based on the geological formation, use a packer or distributor to run a cutting spring to cut the tubing at the corresponding abandoned formation; then attempt injection again. If the injection rate is not less than 18m³, the injection should be successful. 3 If the injection rate is / h, or the injection volume is not lower than the designed nozzle flow rate, then step four can be performed to abandon the oil-water well; if the injection displacement is less than 18m³ / h, then the well can be abandoned. 3 If the injection volume is less than the designed faucet flow rate, this process is not suitable.

[0034] Step 4: Abandoning oil and water wells:

[0035] ① Calculate the amount of cement slurry based on the length of the sealing layer. The volume of the injected cement slurry is the sum of the wellbore volume and the volume of the sealing radius of 1.5m in the target layer. This can better prevent the layer from crossing.

[0036] ② Inject cement slurry through the oil pipe channel to replace the water until there is no cement slurry in the oil pipe above the misalignment, to prevent the upper oil pipe from being unable to be pulled out;

[0037] ③ Allow the cement to solidify completely for at least 48 hours under pressure.

[0038] ④ Determine the cutting depth by using the cement residue inside the test wire probe;

[0039] ⑤ Use the cutting spring to cut open the oil pipe above the gray surface;

[0040] ⑥ Utilize the upper tubing circulation to abandon the upper wellbore space.

[0041] Example 1: Well Gao 145-33

[0042] The tubing string was moved, but had no effective stroke; testing revealed deformation between 751.43m and 754.3m. Trial injection was performed at a rate of 21m³ / h. Calculations indicated a cement slurry usage of 18m³ for this well. Cement slurry was injected through the tubing channel; water was squeezed out until no cement slurry remained above 755m in the tubing; pressure was applied for 50 hours to allow it to set. Using a test wireline, the cement slurry level inside the tubing was determined to be 754m. At 750m, the tubing above the slurry level was cut open; the space between the deformed section and the upper wellbore was filled using the upper tubing. The upper tubing was then removed, and the well was allowed to set for completion.

[0043] Example 2: Well Zhong 100-224

[0044] The tubing string was inactive with no effective travel. Deformation was found at 710.8m during testing. A trial injection was conducted at a rate of 12 m³ / h. Holes were drilled at 835m and 875m, and high-volume circulation was used for unblocking. A pump truck was used for trial injection at a rate of 19 m³ / h. Calculations indicated a cement slurry usage of 15 m³. The cement slurry was injected through the tubing channel. Water was used to replace the cement slurry until no more cement slurry remained above 708m. The tubing was then pressurized and allowed to set for 48 hours. A test wireline was used to probe the cement slurry level inside the tubing, which was found to be 709m. The tubing above the slurry level was cut at 705m. The upper tubing was then circulated through the abandoned section and the space in the upper wellbore to retrieve the upper tubing. The well was then allowed to set and complete.

Claims

1. A process for utilizing the original well casing of an abandoned oil or water well, characterized in that... include: Step 1: Determine if the oil and water well conditions simultaneously meet the following conditions: ① The tubing is movable, and the tubing has no effective stroke; ② The inner diameter of the oil pipe is less than Ф60mm, or the test is blocked; If satisfied, proceed to step two; Step 2: Trial injection, with an injection displacement of not less than 18m³. 3 / h, or, there are no dead nozzles in the tubing and the injection volume is not lower than the design nozzle flow rate. If the above conditions are met, proceed to step four; otherwise, proceed to step three. Step 3: Drill holes in the pipe at the corresponding target layer using a packer or water distributor, and then repeat Step 2. Step 4: Abandoning oil and water wells: ① Calculate the amount of cement grout needed based on the length of the sealing layer; ② Inject cement slurry through the oil pipe channel; ③Replace the water with clean water until there is no cement slurry in the oil pipe above the misalignment; ④ Pressurization and condensation; ⑤ Utilize the cement ash surface inside the test wire probe; ⑥ Cut open the oil pipe above the gray surface; ⑦ Utilize the upper tubing circulation to abandon the upper wellbore space.

2. The process for utilizing the original well tubing to decommission oil and water wells according to claim 1, characterized in that: In step one, if the oil and water well conditions do not simultaneously meet conditions ① and ②, then this process is not applicable to the oil and water well.

3. The process for utilizing the original well casing to decommission oil and water wells according to claim 1, characterized in that: In step three, a hole is drilled in the pipe at the corresponding target layer using a packer or distributor, and then a trial injection is performed. If the injection rate is less than 18m³, the injection will be considered successful. 3 If the injection rate is less than the designed nozzle flow rate, or the injection volume is less than the designed nozzle flow rate, then this process is not suitable for the oil-water well.

4. The process for utilizing the original well casing to decommission oil and water wells according to claim 1, characterized in that: In step four, the time for pressure holding and condensation should be at least 48 hours.

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