Water well immovable string sand consolidation and profile control integrated design method

Abstract

The invention belongs to the field of oil and gas field development, and discloses a water well immovable string sand consolidation and profile control integrated design method which comprises the following steps: firstly, injecting front protection liquid inorganic salt; then a sand consolidation system is injected, and the sand consolidation system is a composite resin sand consolidation system and comprises a composite resin sand consolidation agent, inorganic pore increasing liquid and a composite resin curing agent; and then the main profile control system is injected, a main profile control agent with dual functions of plugging and sand stabilizing is adopted, and the main profile control system is a polyacrylamide gel mixture, and the rear high-strength profile control system is an acrylamide gel mixture. From the angle of integration of profile control and sand consolidation, the injection mode of first sand consolidation and then profile control is successfully tested, profile control liquid can be normally injected after sand consolidation, the problem of well repair after sand consolidation and profile control is avoided, and the success rate of the field test process is 100%; after sand consolidation and profile control, the water well does not produce sand, the oil well shows obvious oil increasing and water reducing effects, and the sand production phenomenon of the oil well is obviously relieved.

Description

Technical Field

[0001] The invention belongs to the field of oil and gas field development and relates to an integrated design method for sand consolidation and profile control of a water well stationary pipe string. Background Art

[0002] The main challenges in the development of the Xinbei Block in the Jilin Oilfield are severe sand production in oil and water wells and ineffective water circulation. Due to the shallow, loosely cemented formations, the Xinbei Block is a high-permeability reservoir. Crossflow in the dominant direction exacerbates sand production in oil wells, leading to blockages and serious production losses. Sand production in water wells, resulting in under-injection and injection suspensions, further exacerbates reservoir heterogeneity, leading to significant inter-layer, intra-layer, and inter-planar variations in fluid production and water content, and overall impacting daily oil production by 14.2%. Therefore, managing sand production in water wells and ineffective water circulation is crucial for stabilizing oil production and controlling water loss in the Xinbei Block.

[0003] Prior to the present invention, the main method for controlling sand production in water wells was regular sand flushing. This method exacerbated the permeability of the area near the wellbore, resulting in increasingly serious sand production. Statistics show that the sand production process of wells with serious sand production is sand production - large amounts of sand production - mud and sand production - sand mud and cement blocks production. In the most serious cases, it even causes casing deformation of the tubing. The main method for controlling sand production in oil wells is sand control. The method is to inject a single sand control agent into the oil well. This sand control agent has a large permeability loss. After construction, the permeability is reduced by about 70%, resulting in a weakened formation fluid supply capacity and reduced oil production. In addition, the sand control agent has a fast solidification time and is a rigid solid after solidification. To avoid the sand control agent solidifying in the wellbore and causing well repair, the tubing must be moved, thereby increasing construction costs. The method for controlling ineffective water circulation is to inject an expandable particle profile control agent into the water well. However, the particle profile control agent has limited control over the migration of free sand in the pores, and sand production still occurs after the water well profile is adjusted. Summary of the Invention

[0004] In order to solve the problems existing in the existing technology, the present invention has formed a technical idea of ​​integrated sand consolidation and profile control with a fixed tubing string, and established a design method for injection parameters. Through the integrated sand consolidation and profile control at the water well end, sand production in oil and water wells can be controlled and invalid water circulation inside the reservoir can be reduced. The injection process of the fixed tubing string is realized, thereby reducing costs and construction risks.

[0005] Integrated technical approach for sand consolidation and profile control in water wells without moving tubing: Based on the sand production characteristics and the severity of invalid water circulation in the Xinbei block, a sand consolidation system with solidification properties is first injected into the water well near-wellbore area to solidify the oil layer, and then a profile control agent with sand stabilization and plugging properties is injected to plug the crossflow channel, thus realizing the integrated technical approach for sand production and invalid water circulation control in oil and water wells.

[0006] Design method of integrated technology for sand consolidation and profile control of water wells without moving pipe strings:

[0007] (1) First, inject the pre-protection liquid. The pre-protection liquid uses inorganic salts with a designed mass concentration of 33%-36%. The sand consolidation system and the profile control system are suspended by the density difference of the liquid. The high-density liquid is first used to replace the low-density liquid (water) in the water well string. After the replacement, the dead zone in the water well string is filled with the protective liquid. Since the high density of the protective liquid is greater than the density of the sand consolidation system and the profile control system, the sand consolidation system and the profile control system are suspended on the protective liquid and cannot enter the dead zone. The sand consolidation system and the profile control system are completely entered into the formation before solidification and gelation, thereby avoiding the sand consolidation system and the profile control system from solidifying and gelling in the wellbore, and realizing the construction of the fixed pipe string.

[0008] (2) The sand consolidation system is then injected. The sand consolidation system adopts a composite resin sand consolidation system mainly composed of a composite resin sand consolidating agent, an inorganic pore-increasing fluid, and a composite resin curing agent. The composite resin sand consolidating agent, the pore-increasing fluid, and the composite resin curing agent are injected in sequence. By regulating the pore-increasing fluid, the permeability loss of the sand consolidation system to the reservoir is controlled. The permeability test of the experimental samples before and after sand consolidation was carried out. The experimental results showed that the permeability loss of the samples was about 20%, which met the site requirements and did not affect the smooth injection of the subsequent profile control system.

[0009] (3) Then the main profile control system is injected, and the main profile control agent with dual functions of plugging and stabilizing sand is used to achieve the plugging of the dominant channel. At the same time, the free sand in the water channel is wrapped in the main profile control fluid, which not only increases the strength of the profile control agent but also plays a role in stabilizing sand. The post-placement high-strength profile control system is used as a sealing section plug, with the purpose of preventing the backflow of the profile control agent and further increasing the sand consolidation effect.

[0010] The main body of the profile control system utilizes a proprietary polyacrylamide gel mixture at a concentration of 0.2%-1%, while the secondary system utilizes a proprietary acrylamide gel mixture at a concentration of 0.2%-6%. This integrated approach of sand consolidation and profile control, with no need for tubing, addresses multiple issues related to sand production and ineffective water circulation in both oil and water wells.

[0011] Specifically, the injection process of the integrated design of sand consolidation and profile control without moving the tubing string is mainly divided into three parts, namely, injection of pre-protection fluid, injection of sand consolidation system, and injection of profile control system.

[0012] (1) Design formula for pre-protection liquid dosage

[0013] Design of pre-protection fluid dosage: The key area to be protected is the casing annulus between the bottom of the perforated section of the target layer and the bottom packer, so as to achieve construction without moving the tubing string. Taking into account the protection fluid replacement time and water dilution, to ensure safe replacement, the optimized pre-protection fluid dosage is 1.03 times the protected volume.

[0014] V 保护 =1.03×V 环空

[0015] Where: V 保护 ——Amount of protective liquid, m 3 ;

[0016] V 环空 --The volume of the casing annulus between the bottom of the perforated section in the target layer and the bottom packer, m 3 .

[0017] (2) Design formula for sand consolidation system dosage

[0018] Design formula for sand consolidation system dosage

[0019] V 固砂剂 =αξπr 2 φh

[0020] V 增孔剂 =1-3 times V 固砂剂

[0021] V 固化剂 = 2 times V 固砂剂

[0022] Where: V 固砂剂 ——Amount of sand consolidating agent, m 3 ;

[0023] V 增孔剂 ——Amount of pore-increasing agent, m 3 ;

[0024] V 固化剂 ——Amount of curing agent, m 3 ;

[0025] α---loss coefficient, taking into account formation dilution (1.03-1.1);

[0026] ξ——dosage coefficient (the optimal dosage is 30%-40% of the pore volume); r—treatment radius, m;

[0027] h—oil layer thickness, m;

[0028] Φ—Effective porosity of oil layer, %.

[0029] (3) Design formula for profile control system dosage

[0030]

[0031] V 后置 =πr 2 φh

[0032] Where: V 主体 ——Main profile control system dosage, m 3 ;

[0033] V 后置 ——Dosage of post-mounted high-strength sectioning system, m 3 ;

[0034] a i —the major semi-axis of the ellipse blocking the i direction, m;

[0035] b i —the minor semi-axis of the ellipse blocking the i direction, m;

[0036] h1—the average value of the sum of the thickness in the direction of water well i and oil well, m;

[0037] Φ—effective porosity of oil layer, %;

[0038] Swi—bound water saturation, %;

[0039] n-strong injection and production direction;

[0040] r—processing radius; m.

[0041] (4) Injection pressure design: During the construction process, the pressure is less than the formation fracture pressure

[0042] P 施工 <P 破裂压力 -0.5

[0043] (5) Injection displacement design: Different injection processes use different injection displacements

[0044] Pre-protection liquid injection displacement: normal water injection speed;

[0045] Injection volume of sand consolidation system: 10-12m 3 / Hour;

[0046] Injection rate of the main profile control system: 1-2m 3 / Hour;

[0047] Rear high-intensity sectioning system displacement: 4-6m 3 / Hour.

[0048] Compared with the prior art, the present invention has the following beneficial effects:

[0049] The present invention was tested on 15 wells in the Xinbei block of Jilin Oilfield. From the perspective of integrated profile control and sand consolidation, the injection method of first consolidating sand and then profile control was successfully tested. Profile control fluid can be injected normally after sand consolidation, and there is no problem of well repair after sand consolidation and profile control. The field test process success rate is 100%. After sand consolidation and profile control, no sand production occurs in water wells, and the oil wells show obvious oil-increasing and water-reducing effects, and the sand production phenomenon in the oil wells is significantly alleviated. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1This is a schematic diagram of the reservoir sand production principle;

[0051] Figure 2 This is the permeability change diagram before and after sand consolidation;

[0052] Figure 3 It is a schematic diagram of the integrated process of sand consolidation and profile control. DETAILED DESCRIPTION

[0053] To make the technical solutions and technical advantages of the present invention more clear, the following will provide a clear and complete description of the technical solutions during the implementation of the present invention, combined with the actual application process of the present invention in the geological sealing process of a deep saline water layer in Jilin and the accompanying drawings.

[0054] Example 1

[0055] First inject the pre-protection liquid, calculate the amount of 3 cubic meters, and inject at the water injection speed. Then inject the sand consolidation system, and inject the sand consolidation agent 3.5m 3 , pore increasing liquid volume 10m 3 , curing agent 7m 3 , the displacement design of sand consolidation system is 10m 3 / hour, wait for 24 hours to solidify. Finally, inject the profile control system. The main profile control system is designed to be 748m 3 , displacement design 2m 3 / hour, rear high-intensity sectioning system design 24m 3 , displacement design 4m 3 / hour. Inject displacement fluid (water) to complete the construction.

[0056] Example 2

[0057] First inject the pre-protection liquid, calculate the dosage of 3.5 cubic meters, and inject at the water injection speed. Then inject the sand consolidation system, and inject the sand consolidation agent 2.5m 3 , the volume of pore increasing liquid is 7.5m 3 , curing agent 5m 3 , the displacement design of sand consolidation system is 10m 3 / hour, wait for 24 hours to solidify. Finally, inject the profile control system. The main profile control system is designed to be 612m 3 , displacement design 2m 3 / hour, rear high-intensity sectioning system design 24m 3 , displacement design 4m 3 / hour. Inject displacement fluid (water) to complete the construction.

[0058] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. An integrated design method for sand consolidation and profile control of a water well with a fixed pipe string, characterized in that: The steps include: (1) First inject the pre-protection liquid inorganic salts; (2) Re-injecting a sand consolidation system, wherein the sand consolidation system adopts a composite resin sand consolidation system, including a composite resin sand consolidation agent, an inorganic pore-increasing fluid, and a composite resin curing agent; (3) Then, the main profile control system is injected, and the main profile control agent with dual functions of plugging and sand stabilization is used, including the main profile control system: polyacrylamide gel mixture and the post-high-intensity profile control system: acrylamide gel mixture.

2. The integrated design method for sand consolidation and profile control of a water well fixed pipe string according to claim 1 is characterized in that: The amount of pre-protection liquid used is 1.03 times the volume to be protected.

3. The integrated design method for sand consolidation and profile control of a water well fixed pipe string according to claim 1 is characterized in that: The mass concentration of the pre-protection solution is 33%-36%.

4. The integrated design method for sand consolidation and profile control of a water well fixed pipe string according to claim 1 is characterized in that: The injection order of the sand consolidation system is composite resin sand consolidating agent, pore increasing fluid, and composite resin curing agent.

5. The integrated design method for sand consolidation and profile control of a water well fixed pipe string according to claim 1 is characterized in that: The calculation formula for the amount of sand consolidation system is: V 固砂剂 =aξπr 2 φh V 增孔剂 =1-3 times V 固砂剂 V 固化剂 =2 times V 固砂剂 Where: V 固砂剂 ——Amount of sand consolidating agent, m 3 ; V 增孔剂 ——Amount of pore-increasing agent, m 3 ; V 固化剂 ——Amount of curing agent, m 3 ; α---loss coefficient, taking into account formation dilution (1.03-1.1); ξ——dosage coefficient (the optimal dosage is 30%-40% of the pore volume); r—processing radius, m; h—oil layer thickness, m; Φ—Effective porosity of oil layer, %.

6. The integrated design method for sand consolidation and profile control of a water well fixed pipe string according to claim 1 is characterized in that: The mass concentration of the main profile control system is 0.2%-1%.

7. The integrated design method for sand consolidation and profile control of a water well fixed pipe string according to claim 1 is characterized in that: The mass concentration of the post-high-intensity profiling system is 0.2%-6%.

8. The integrated design method for sand consolidation and profile control of a water well fixed pipe string according to claim 1, characterized in that: The calculation formula for the dosage of the profile control system is: V 后置 =πr 2 φh Where: V 主体 ——Main profile control system dosage, m 3 ; V 后置 ——Dosage of post-mounted high-strength sectioning system, m 3 ; a i —the major semi-axis of the ellipse blocking the i direction, m; b i —the minor semi-axis of the ellipse blocking the i direction, m; h1—the average value of the sum of the thickness in the direction of water well i and oil well, m; Φ—effective porosity of oil layer, %; Swi—bound water saturation, %; n-strong injection and production direction; r—processing radius; m.

9. The integrated design method for sand consolidation and profile control of a water well fixed pipe string according to claim 1, characterized in that: Injection pressure design: During the construction process, the pressure is less than the formation fracture pressure; P 施工 <P 破裂压力 -0.5。 10. The integrated design method for sand consolidation and profile control of a water well fixed pipe string according to claim 1, characterized in that: Pre-protection liquid injection displacement: normal water injection speed; Injection volume of sand consolidation system: 10-12m 3 / Hour; Injection rate of the main profile control system: 1-2m 3 / Hour; Rear high-intensity sectioning system displacement: 4-6m 3 / Hour.

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