Dual-purpose non-acid plug removal fluid sand washing fluid system and application

Abstract

The invention provides a dual-purpose non-acid plug removal fluid sand washing fluid system and application, the non-acid plug removal fluid sand washing fluid system comprises the following raw materials: a non-acid plug removal fluid, a weighting agent, a tackifying and shear strength improving agent, a clay stabilizer, a discharge aiding agent and methanol, and the non-acid plug removal fluid sand washing fluid system not only can be used as a sand washing fluid, but also can be used as a plug removal fluid; according to the continuous oil pipe plug removal device, the integration of shaft plug removal, reservoir plug removal and ground plug removal is achieved, the reservoir is effectively protected, the operation cost is reduced, safety and environment protection are improved, and the problems that the plug removal efficiency of the continuous oil pipe of the high-wax-content well is not high and the effect is not good are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil and gas field development, and particularly relates to a dual-purpose non-acid plugging removal fluid and sand washing fluid system and its application. Background Art

[0002] The plugging types of oilfield gas wells include formation sand production and scaling caused by changes in the in-situ stress field and temperature field, and paraffin wax precipitation and hydrate formation in the wellbore caused by changes in the wellbore temperature field. Therefore, it is necessary to restore the productivity of a single well through coiled tubing dredging operations.

[0003] As Figure 2 shown, at present, coiled tubing dredging operations usually require semi-well killing, and the working fluid is mostly organic salts. During the dredging operation, if the wellhead pressure control is too high or the operation is improper, the organic salts will enter the formation, pollute the reservoir, and reduce the productivity of a single well. On the other hand, due to paraffin wax sticking to the inner wall of the tubing in high-wax wells, coiled tubing removes paraffin wax in large-diameter tubing through mechanical action, resulting in problems such as low plugging removal efficiency and poor effect. Summary of the Invention

[0004] In order to solve the problems existing in the prior art, the present invention provides a dual-purpose non-acid plugging removal fluid and sand washing fluid system and its application. The non-acid plugging removal fluid and sand washing fluid system can be used as both a sand washing fluid and a plugging removal fluid, realizing the integration of wellbore plugging removal, reservoir plugging removal, and surface plugging removal, effectively protecting the reservoir, reducing the operation cost, achieving a double improvement in safety and environmental protection, and solving the problems of low plugging removal efficiency and poor effect of coiled tubing in high-wax wells.

[0005] To achieve the above object, the present invention provides the following technical solution: A dual-purpose non-acid plugging removal fluid and sand washing fluid system, the raw materials of which include: non-acid plugging removal fluid, weighting agent, viscosity increasing and shear strengthening agent, clay stabilizer, drainage aid, and methanol.

[0006] Further, by mass percentage, the raw materials include 75%-80% non-acid plugging removal fluid + 5%-10% weighting agent + 1%-2% viscosity increasing and shear strengthening agent + 2%-4% clay stabilizer + 2%-4% drainage aid + 5%-10% methanol.

[0007] Further, the weighting agent is potassium formate or potassium chloride.

[0008] Further, the viscosity increasing and shear strengthening agent is xanthan gum, carboxymethyl cellulose, or guar gum.

[0009] Further, the clay stabilizer is potassium chloride or polyquaternary ammonium salt.

[0010] Further, the drainage aid is a surfactant.

[0011] The present invention also provides an application of the dual-purpose non-acid plugging removal fluid and sand washing fluid system, and the specific steps are as follows:

[0012] S1 uses the above non - acid plug - removing and sand - washing fluid system for coiled tubing dredging operations;

[0013] After the coiled tubing dredging operation is completed, the non - acid plug - removing and sand - washing fluid system is displaced into the formation for reservoir scale removal;

[0014] After the reservoir scale is removed, the well is opened for blowout so that the non - acid plug - removing and sand - washing fluid system flows back into the surface pipeline for scale removal of the surface pipeline.

[0015] Further, in S1, the non - acid plug - removing and sand - washing fluid system is heated to 50°C - 60°C for coiled tubing dredging operations.

[0016] Further, in S1, the density of the non - acid plug - removing and sand - washing fluid system is 1.0 g / cm 3 ~1.5 g / cm 3 .

[0017] Further, the non - acid plug - removing and sand - washing fluid system is used for coiled tubing dredging operations in high - wax wells.

[0018] Compared with the prior art, the present invention has at least the following beneficial effects:

[0019] The present invention provides a dual - purpose non - acid plug - removing and sand - washing fluid system. Using non - acid plug - removing fluid as the raw material, the non - acid plug - removing fluid can replace the organic salt during coiled tubing dredging operations, which can not only realize coiled tubing dredging operations; and the non - acid plug - removing fluid has no harm to the formation and has the function of protecting the reservoir. Even if the liquid leaks into the formation during coiled tubing operations, it will not pollute the reservoir; the weighting agent is used to adjust the density of the non - acid plug - removing fluid, increase the liquid specific gravity, achieve semi - kill well, and meet the wellhead pressure control conditions; the viscosifier and gel breaker can improve the liquid carrying capacity; the clay stabilizer can prevent the swelling of reservoir clay minerals after absorbing water and blocking the pore throats; the flowback aid can reduce the capillary force of the liquid in the reservoir pore throats and improve the flowback effect; methanol can prevent the reduction of single - well production capacity caused by formation water blockage; therefore, the non - acid plug - removing and sand - washing fluid system of the present invention can not only meet the requirements of semi - kill well circulation flushing and plug removal during coiled tubing dredging operations, but also greatly improve the coiled tubing dredging efficiency in high - wax wells, forming a set of sand - washing fluid system suitable for high - wax wells.

[0020] When the non - acid plug - removing and sand - washing fluid system of the present invention is used, it realizes the integration of wellbore plug removal, reservoir plug removal, and surface plug removal, effectively improving the adaptability of coiled tubing operations, avoiding reservoir pollution caused by the dredging process, and at the same time increasing the single - well production capacity. More importantly, it plays an important supporting role in oil and gas field development. In terms of economic benefits, "one fluid for two uses" can reduce the operation cost and achieve quality improvement and efficiency increase. Brief Description of the Drawings

[0021] Figure 1Schematic flow chart of the continuous coiled tubing unclogging method of the present invention;

[0022] Figure 2 Schematic diagram of organic salts entering the formation and polluting the reservoir;

[0023] Figure 3 Scale dissolving process of non-acid plugging removal fluid;

[0024] Figure 4 Corrosion rate comparison between acid plugging removal fluid and non-acid plugging removal fluid. Specific implementation manners

[0025] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation manners.

[0026] The present invention provides a non-acid plugging removal fluid and sand washing fluid system for coiled tubing unclogging. In terms of mass percentage, the raw materials include 75%-80% non-acid plugging removal fluid + 5%-10% weighting agent + 1%-2% viscosity increasing and shear strengthening agent + 2%-4% clay stabilizer + 2%-4% flowback aid + 5%-10% methanol;

[0027] Preferably, the non-acid plugging removal fluid is a plugging removal fluid system for reservoir stimulation, mainly including alkaline plugging removal fluid and neutral plugging removal fluid. The sand washing fluid system of the present invention adopts non-acid plugging removal fluid, which can replace organic salts during the continuous coiled tubing unclogging operation, and can not only achieve the continuous coiled tubing unclogging operation; moreover, the non-acid plugging removal fluid has no harm to the formation and has the function of protecting the reservoir. Even if the liquid leaks into the formation during the continuous coiled tubing operation, it will not pollute the reservoir.

[0028] Preferably, the weighting agent includes potassium formate or potassium chloride, and its function is to adjust the density of the non-acid plugging removal fluid and sand washing fluid system to 1.0 g / cm 3 ~1.5 g / cm 3 , increase the liquid specific gravity, achieve semi-well killing, and meet the wellhead pressure control conditions.

[0029] Preferably, the viscosity increasing and shear strengthening agent includes xanthan gum, carboxymethyl cellulose, guar gum, etc., and its function is to improve the liquid carrying capacity;

[0030] Preferably, the clay stabilizer includes potassium chloride, polyquaternary ammonium salt, etc., and its function is to prevent the reservoir clay minerals from swelling and blocking the pore throats after absorbing water;

[0031] Preferably, the flowback aid includes surfactants, and its function is to reduce the capillary force of the liquid in the reservoir pore throats and improve the flowback effect;

[0032] Preferably, the main function of methanol is to prevent the reduction of single well productivity caused by formation water lock.

[0033] Such as Figure 1As shown in the figure, when using the above non-acid plugging removal and sand washing fluid system for coiled tubing dredging, it includes two processes: the dredging process and the plugging removal process. The specific steps are as follows:

[0034] S1. Coiled tubing dredging operation process: Heat the above non-acid plugging removal and sand washing fluid system to 50°C - 60°C for coiled tubing dredging operation, which can not only achieve semi-kill circulation flushing and plugging removal operation, but also prevent liquid leakage into the formation and pollute the reservoir;

[0035] S2. Reservoir plugging removal: After the coiled tubing dredging operation is completed, displace the non-acid plugging removal and sand washing fluid system into the formation. The non-acid plugging removal and sand washing fluid system of the present invention can remove the scale of carbonates and sulfates, and has a good plugging removal effect. Therefore, displacing all the non-acid plugging removal and sand washing fluid system into the formation can relieve the scale plugging of the production layer and increase the single-well production.

[0036] S3. Surface plugging removal: Open the well for blowout to make the non-acid plugging removal and sand washing fluid system flow back into the surface pipeline for scale removal of the surface pipeline.

[0037] The present invention effectively combines wellbore plugging removal, reservoir plugging removal and surface plugging removal to form an all-round three-dimensional plugging removal process. As Figure 4 shown, during the dredging process, the corrosion rate of the non-acid plugging removal and sand washing fluid system is 0.027 g / (m 2 .h), approaching "zero corrosion". Therefore, using the non-acid plugging removal and sand washing fluid system during the dredging operation can effectively protect the tubing string and avoid corrosion damage to the integrity of the tubing during the operation; as Figure 3 shown, the non-acid plugging removal and sand washing fluid system of the present invention has obvious dissolving ability for scale. Therefore, after the dredging operation process is completed, the non-acid plugging removal and sand washing fluid can be displaced into the formation to relieve the scale plugging of the production layer. Finally, open the well for flow back, the non-acid plugging removal and sand washing fluid enters the surface pipeline for surface scale removal.

[0038] Example 1

[0039] When using a non-acid plugging removal and sand washing fluid system provided by the present invention for coiled tubing dredging, it includes two processes: the dredging process and the plugging removal process, as follows:

[0040] S1. Dredging process: Using non-acid plugging removal fluid to replace organic salts can not only achieve coiled tubing dredging operation, but also prevent liquid leakage into the formation and pollute the reservoir.

[0041] First, semi-kill can be achieved by adding weighting materials to the non-acid plugging removal fluid, reducing the wellhead pressure and ensuring well control safety. The density of the non-acid plugging removal fluid can be weighted up to 1.5 g / cm 3 , for a 6000m well, the wellhead pressure can be reduced by 30 MPa.

[0042] Second, a sand washing fluid system of "80% neutral plugging removal fluid + 7% potassium formate + 2% xanthan gum + 3% potassium chloride + 3% surfactant + 5% methanol + temperature increase of 50°C - 60°C" is formed, so as to meet the requirements of coiled tubing circulating flushing and plugging removal, greatly improve the coiled tubing dredging efficiency of high-wax wells, and can become the first choice for the dredging process of high-wax wells.

[0043] S2. Plugging removal process: Optimize the construction process. After the coiled tubing dredging operation is completed, then displace the non-acid plugging removal fluid sand washing fluid system into the formation to remove the scale plugging of the production layer and improve the single-well production capacity. At the same time, the non-acid plugging removal fluid sand washing fluid system has almost zero corrosion, can be opened for backflow into the surface process, and also has a scale removal effect on the surface pipeline, realizing the effective combination of wellbore plugging removal, reservoir plugging removal and surface plugging removal.

[0044] Example 2

[0045] When using the above non-acid plugging removal fluid sand washing fluid system for coiled tubing dredging, it includes two processes, the dredging process and the plugging removal process. The specific steps are as follows:

[0046] S1. Coiled tubing dredging operation process: Use the non-acid plugging removal fluid sand washing fluid system for coiled tubing dredging operation;

[0047] The non-acid plugging removal fluid sand washing fluid system includes: 75% neutral plugging removal fluid + 10% potassium chloride + 1% carboxymethyl cellulose + 2% polyquaternary ammonium salt + 2% surfactant + 10% methanol;

[0048] S2. Reservoir plugging removal: After the coiled tubing dredging operation is completed, displace the non-acid plugging removal fluid sand washing fluid system into the formation to remove the scale plugging of the production layer.

[0049] S3. Surface plugging removal: Open the well for blowout to make the non-acid plugging removal fluid sand washing fluid system flow back into the surface pipeline to remove the scale of the surface pipeline.

[0050] Example 3

[0051] When using the above non-acid plugging removal fluid sand washing fluid system for coiled tubing dredging, it includes two processes, the dredging process and the plugging removal process. The specific steps are as follows:

[0052] S1. Coiled tubing dredging operation process: Use the non-acid plugging removal fluid sand washing fluid system for coiled tubing dredging operation;

[0053] The non-acid plugging removal fluid sand washing fluid system includes: 78% alkaline plugging removal fluid + 5% potassium chloride + 1.5% guar gum + 3.5% polyquaternary ammonium salt + 2% surfactant + 10% methanol;

[0054] S2. Reservoir plugging removal: After the coiled tubing dredging operation is completed, displace the non-acid plugging removal fluid sand washing fluid system into the formation to remove the scale plugging of the production layer.

[0055] S3. Surface unblocking: Open the well and spray to make the non-acid unblocking fluid and sand flushing fluid system flow back into the surface pipeline to descale the surface pipeline.

[0056] Example 4

[0057] When the above non-acid plugging removal fluid sand flushing fluid system is used to dredge the coiled tubing, there are two processes, the dredging process and the plugging removal process. The specific steps are as follows:

[0058] S1. Continuous tubing dredging process: Use non-acid plugging removal fluid and sand flushing fluid system to dredge the continuous tubing;

[0059] The non-acid plugging removal fluid sand flushing fluid system includes: 76% alkaline plugging removal fluid + 5% potassium chloride + 1% carboxymethyl cellulose + 4% polyquaternary ammonium salt + 4% surfactant + 10% methanol;

[0060] S2. Reservoir unblocking: After the continuous tubing unblocking operation is completed, the non-acid unblocking fluid and sand flushing fluid system is displaced into the formation to remove the scale blockage in the production layer.

[0061] S3. Ground unblocking: Open the well and spray to make the non-acid unblocking fluid and sand flushing fluid system flow back into the ground pipeline to descale the ground pipeline.

[0062] Example 5

[0063] When the above non-acid plugging removal fluid sand flushing fluid system is used to dredge the coiled tubing, there are two processes, the dredging process and the plugging removal process. The specific steps are as follows:

[0064] S1. Continuous tubing dredging process: Use non-acid plugging removal fluid and sand flushing fluid system to dredge the continuous tubing;

[0065] The non-acid plugging removal fluid sand flushing fluid system includes: 80% alkaline plugging removal fluid + 10% potassium chloride + 1% carboxymethyl cellulose + 2% polyquaternary ammonium salt + 2% surfactant + 5% methanol;

[0066] S2. Reservoir unblocking: After the continuous tubing unblocking operation is completed, the non-acid unblocking fluid and sand flushing fluid system is displaced into the formation to remove the scale blockage in the production layer.

[0067] S3. Ground unblocking: Open the well and spray to make the non-acid unblocking fluid and sand flushing fluid system flow back into the ground pipeline to descale the ground pipeline.

[0068] The non-acid plugging removal and sand washing fluid system of the present invention realizes the integration of wellbore plugging removal, reservoir plugging removal, and surface plugging removal, effectively improving the adaptability of coiled tubing operations, avoiding reservoir pollution caused by the dredging process, and at the same time increasing the single-well production capacity. More importantly, it plays an important supporting role in the development of oil and gas fields. In terms of economic benefits, "one fluid for two uses" can reduce operation costs and achieve quality improvement and efficiency increase. The method of the present invention has been applied 6 times in the Boda Oil and Gas Production Management Area of the Tarim Oilfield, with a process success rate of 100%. It has been comprehensively promoted and applied. In 2022, the cumulative gas increase was 72 million cubic meters, the oil increase was 8,400 tons, the new profit was 94.92 million yuan, and the cost reduction was 5.016 million yuan. In terms of safety risks, "zero corrosion" of the pipe string and surface pipelines is achieved. At the same time, the non-acid plugging removal fluid can be directly put into production without backflow, saving energy and reducing emissions at the source, and achieving double improvements in safety and environmental protection.

Claims

1. A dual-purpose non-acid plugging removal liquid and sand flushing liquid system, characterized in that: Ingredients include: Non-acid plugging-removing fluid, weighting agent, viscosity-enhancing and shear-enhancing agent, clay stabilizer, drainage aid and methanol.

2. A dual-purpose non-acid plugging removal and sand flushing liquid system according to claim 1, characterized in that: In terms of mass percentage, the raw materials include 75%-80% non-acid plugging removal liquid + 5%-10% weighting agent + 1%-2% viscosity increasing and shearing agent + 2%-4% clay stabilizer + 2%-4% drainage aid + 5%-10% methanol.

3. A dual-purpose non-acid plugging removal and sand flushing liquid system according to claim 1, characterized in that: The weighting agent is potassium formate or potassium chloride.

4. A dual-purpose non-acid plugging removal and sand flushing liquid system according to claim 1, characterized in that: The viscosity increasing and shearing enhancing agent is xanthan gum, carboxymethyl cellulose or guar gum.

5. The dual-purpose non-acid plugging removal and sand flushing liquid system according to claim 1 is characterized in that: The clay stabilizer is potassium chloride or polyquaternium salt.

6. A dual-purpose non-acid plugging removal and sand flushing fluid system according to claim 1, characterized in that: The drainage aid is a surfactant.

7. Application of a dual-purpose non-acid plugging removal liquid and sand flushing liquid system, characterized in that: The specific steps are as follows: S1: using the non-acid plugging removal fluid and sand flushing fluid system described in any one of claims 1 to 6 to perform coiled tubing dredging operations; After the S2 coiled tubing dredging operation is completed, the non-acid plugging removal fluid and sand flushing fluid system is displaced into the formation to remove reservoir scale; After the S3 reservoir is descaled, the well is opened and blown to allow the non-acid plugging removal fluid and sand flushing fluid system to flow back into the surface pipeline to descale the surface pipeline.

8. The use of a dual-purpose non-acid plugging removal liquid sand flushing liquid system according to claim 7, characterized in that: In S1, the non-acid plugging removal fluid and sand flushing fluid system is heated to 50°C-60°C to perform coiled tubing dredging operations.

9. The use of a dual-purpose non-acid plugging removal liquid sand flushing liquid system according to claim 7, characterized in that: In S1, the density of the non-acid plugging solution and sand flushing fluid system is 1.0 g / cm 3 ~1.5g / cm 3 .

10. The use of a dual-purpose non-acid plugging removal liquid sand flushing liquid system according to claim 7, characterized in that: The non-acid plugging removal fluid and sand flushing fluid system is used for the coiled tubing dredging operation of high-wax content wells.

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