A water plugging method for oil and water wells

Abstract

The invention discloses a water plugging method for oil and water wells, comprising: in the profile adjustment stage of water injection wells, firstly, three-stage water plugging and profile adjustment are performed on the water flow advantage channel formed by the previous water injection, and then the water plugging agent in the wellbore is replaced by clean water to enter the formation; after the profile adjustment of the water injection well is completed, the wellhead pressure of the oil well is monitored; when the wellhead pressure of the oil well is less than the preset pressure, the three-stage plugging water plugging agent is first respectively transported to the deep bedrock pores of the formation through the fracturing cracks, and then the water plugging agent in the fracturing cracks is replaced by cross-linked guar gum into the matrix micro-cracks, and the well is closed and solidified to complete the construction. Bidirectional water plugging is performed in water injection wells and oil wells, which can not only form a high-pressure area in the strong water channeling channel, achieve diversion, and generate bypass flow, but also provide multiple diversion opportunities to expand the bypass water drive space; at the same time, the bidirectional water plugging extends the communication distance of the bypass flow space on both sides of the oil and water wells, and multiplies the displacement effect; it can reduce the water content of the oil well, greatly increase the daily oil production, extend the life of the oil well, and improve the crude oil recovery rate.

Description

Technical Field

[0001] The invention belongs to the technical field of oil field exploitation and relates to a water plugging method for an oil and water well. Background Art

[0002] For low permeability reservoirs, water injection through perforation of water wells and sand fracturing of oil wells are mainly used for development. As the development time increases, problems such as rapid increase in water content in the oil wells affected by water injection, water breakthrough and water flooding occur, resulting in low crude oil recovery rate.

[0003] For water injection development and high water-content oil wells, the main methods of water plugging in the early stage are one-way water well profile adjustment or oil well water plugging. However, for oil and water wells with high water channeling intensity between wells in regional units, simple water well profile adjustment or oil well water plugging is difficult to plug, and the effective period is short and easy to break through again. Therefore, it is urgent to summarize the previous experience, combine the distribution characteristics of residual oil in water drive, and study an effective water plugging method to improve the displacement effect and achieve the purpose of increasing crude oil recovery. Summary of the invention

[0004] The purpose of the present invention is to provide a water plugging method for oil and water wells, which solves the problem of difficulty in plugging oil and water wells with high inter-well water crossover intensity in the prior art.

[0005] The technical solution adopted by the present invention is a water plugging method for oil and water wells, comprising the following steps:

[0006] Step 1: During the water injection well profile control stage, firstly perform three-level water plugging and profile control on the water flow advantage channel formed by the previous water injection, and then use clean water to displace the water plugging agent in the wellbore and enter the formation;

[0007] Step 2: After the water injection well profile adjustment is completed, the wellhead pressure of the oil well is monitored;

[0008] Step 3: When the wellhead pressure of the oil well is lower than the preset pressure, the three-stage plugging water-blocking agent is first transported to the bedrock pores deep in the formation through the fracturing cracks, and then the water-blocking agent in the fracturing cracks is displaced into the matrix micro-cracks by cross-linked guar gum, and the well is shut down for solidification to complete the construction.

[0009] The present invention is also characterized in that:

[0010] The three-stage water plugging and profile control plugging process in step 1 is: nano-scale microspheres, micron-scale PEG gel particles, and phenolic resin weak gel are graded and pumped into the water flow dominant channel formed by the previous water injection.

[0011] The specific process of step 1 is as follows: In the water injection well profile adjustment stage, firstly inject 1.0-2.0m 3 / h2800-3200m 3 The nano-scale microspheres are injected into the water flow advantage channel formed by the previous water injection, and then injected into the water flow channel at a rate of 1.0-2.0 m3 / h displacement will be 1800-2100m 3 PEG gel particles are injected into the water flow advantage channel formed by the early water injection, and then the injection displacement is 1.0-2.0m 3 / h50-100m 3 Phenolic resin weak gel is injected into the water flow dominant channel formed by the early water injection, and finally the water flow is less than 3m 3 / h construction displacement using 5-8m 3 Clean water displaces the water plugging agent in the wellbore and enters the formation.

[0012] The three-stage plugging agent in step 3 includes nano-scale microspheres, PEG gel particle profile control, and mixed plugging agent, and the mixed plugging agent is a mixture of phenolic resin gel and quartz sand particles.

[0013] Step 3 is as follows: First, the fracture is 0.3-0.5m 3 200-250m / min 3 Microspheres are injected into the water channel to block the matrix pores, and then the fractures are fractured to form a 0.3-0.5m 3 200-250m / min 3 Gel particles are injected into the water channel to block the micro cracks, and then the fractures are hydraulically fractured to 0.5-0.8m 3 300-400m / min 3 The mixed water plugging agent is injected into the water channel to plug the water cracks. Finally, 80-100m 3 Cross-linked guar gum with a content of less than 0.5 μm 3 The construction displacement of / min displaces the water plugging agent in the artificial cracks into the matrix micro-cracks, reserving artificial cracks as channels for later fluid production.

[0014] The preset pressure in step 3 is 5 MPa.

[0015] The volume ratio of phenolic resin gel to quartz sand particles in the mixed water plugging agent is 8 to 8.5:2.

[0016] The beneficial effects of the present invention are:

[0017] The invention discloses a water plugging method for oil and water wells. Bidirectional water plugging is performed on water injection wells and oil wells, which can not only form a high-pressure area in a strong water channeling channel to achieve turning and generate bypass flow, but also provide multiple turning opportunities to expand bypass water drive space; at the same time, the bidirectional water plugging lengthens the communication distance of the bypass flow space on both sides of the oil and water wells, and improves the displacement effect by many times; it can reduce the water content of the oil well, greatly increase the daily oil production, extend the life of the oil well, and improve the crude oil recovery rate. DETAILED DESCRIPTION

[0018] The present invention is described in detail below in conjunction with specific implementation modes.

[0019] A water plugging method for an oil and water well comprises the following steps:

[0020] Before plugging, it is necessary to select suitable oil and water wells for plugging by analyzing the reservoir development dynamics and water breakthrough characteristics; in this embodiment, the oil well is a pore-fracture type with water breakthrough, the water channeling intensity between the oil and water wells is large, the oil well is flooded, and the wellhead pressure reaches 8-10MPa;

[0021] Step 1: During the water injection well profile control stage, firstly perform three-level water plugging and profile control on the water flow advantage channel formed by the previous water injection, and then use clean water to displace the water plugging agent in the wellbore and enter the formation;

[0022] Specifically, during the water injection well profile adjustment stage, the injection rate is 1.0-2.0m 3 / h2800-3200m 3 The nano-scale microspheres are injected into the water flow advantage channel formed by the early water injection, and then the injection displacement is 1.0-2.0m 3 / h1800-2100m 3 PEG gel particles are injected into the water flow advantage channel formed by the early water injection, and then the injection displacement is 1.0-2.0m 3 / h50-100m 3 Phenolic resin weak gel is injected into the water flow dominant channel formed by the early water injection, and finally the water flow is less than 3m 3 / h construction displacement using 5-8m 3 Clean water displaces the water plugging agent in the wellbore and enters the formation.

[0023] Step 2: After the water injection well profile adjustment is completed, the wellhead pressure of the oil well is monitored;

[0024] Step 3: When the wellhead pressure of the oil well is less than 5MPa, start plugging the oil well. Since the target oil wells have been fractured, the oil layer near the wellbore area forms a dual-medium seepage characteristic of fracture-pore, with fracture seepage as the main flow and pore seepage as the auxiliary flow. First, the three-stage plugging water-blocking agent is transported to the deep bedrock pores of the formation through the fractured fractures, and then the cross-linked guar gum is used to displace the water-blocking agent in the fractured fractures into the matrix micro-fractures, and the well is shut down for solidification to complete the construction;

[0025] Furthermore, the three-stage plugging agent includes nano-scale microspheres, PEG gel particle profile control, and mixed water plugging agent, and the mixed water plugging agent is a mixture of phenolic resin gel and quartz sand particles (40-70 mesh) in a volume ratio of 8 to 8.5:2.

[0026] Specifically, firstly, the fracture is 0.3-0.5m 3 200-250m / min 3 Microspheres are injected into the water channel to block the matrix pores, and then the fractures are fractured to form a 0.3-0.5m 3200-250m / min 3 Gel particles are injected into the water channel to block the micro cracks, and then the fractures are hydraulically fractured to 0.5-0.8m 3 300-400m / min 3 The mixed water plugging agent is injected into the water channel to plug the water cracks. Finally, 80-100m 3 Cross-linked guar gum with a content of less than 0.5 μm 3 / min construction displacement will displace the water plugging agent in the artificial fractures into the matrix micro-fractures, leaving artificial fractures as channels for later fluid production. The well will be shut down and solidified for 72 hours to end the entire construction.

[0027] Example 1

[0028] In this embodiment, the oil well is of pore-fracture type with water breakthrough, the water crossover between oil and water wells is strong, the oil well is flooded, and the wellhead pressure reaches 10MPa;

[0029] Step 1: During the water injection well profile control stage, firstly perform three-level water plugging and profile control on the water flow advantage channel formed by the previous water injection, and then use clean water to displace the water plugging agent in the wellbore and enter the formation;

[0030] Specifically, during the water injection well profile adjustment stage, the injection rate is 1.8m 3 / h3200m 3 The nano-scale microspheres are injected into the water flow advantage channel formed by the previous water injection, and then injected into the 1.6m 3 / h displacement will be 2000m 3 PEG gel particles were injected into the water flow dominant channel formed by the previous water injection, and then the injection displacement was 1.4m 3 / h 80m 3 Phenolic resin weak gel is injected into the water flow dominant channel formed by the early water injection, and finally the water flow is less than 3m 3 / h construction displacement using 6m 3 Clean water displaces the water plugging agent in the wellbore and enters the formation.

[0031] Step 2: After the water injection well profile adjustment is completed, the wellhead pressure of the oil well is monitored;

[0032] Step 3: When the wellhead pressure of the oil well drops to 4.5MPa, start plugging the oil well. Since the oil wells have been fractured, the oil layer near the wellbore area forms a dual-medium seepage characteristic of fracture-pore, with fracture seepage as the main flow and pore seepage as the auxiliary flow. First, the three-stage plugging water-blocking agent is transported to the deep bedrock pores of the formation through the fractured fractures, and then the cross-linked guar gum is used to displace the water-blocking agent in the fractured fractures into the matrix micro-fractures, and the well is shut down for solidification to complete the construction;

[0033] Furthermore, the three-stage plugging agent includes nano-scale microspheres, PEG gel particle profile control, and a mixed plugging agent, and the mixed plugging agent is a mixture of phenolic resin gel and quartz sand particles (40-70 mesh) in a volume ratio of 8.1:2.

[0034] Specifically, firstly, the fracture is 0.4m 3 / min250m 3 Microspheres are injected into the water channel to block the matrix pores, and then the fractures are fractured with a depth of 0.5 m. 3 / min200m 3 Gel particles are injected into the water channel to plug the micro cracks, and then the fractures are fractured to 0.8m 3 / min350m 3 The mixed water plugging agent was injected into the water channel to plug the water cracks. Finally, 85m 3 Cross-linked guar gum with a content of less than 0.5 μm 3 / min construction displacement will displace the water plugging agent in the artificial fractures into the matrix micro-fractures, leaving artificial fractures as channels for later fluid production. The well will be shut down and solidified for 72 hours to end the entire construction.

[0035] In June 2019, the oil and water wells were plugged in accordance with this embodiment, the strong water channel between oil and water was plugged, the water drive direction was redirected, a bypass water drive space was formed, and an effective displacement system was re-established. In the initial stage (the first 3 months), the water content of the oil wells decreased by an average of 72%, and the daily oil production increased by an average of 1.85 tons / day. The water plugging period is still valid for 26 months as of now (July 2021).

[0036] Example 2

[0037] In this embodiment, the oil well is of pore-fracture type with water breakthrough, the water crossover between oil and water wells is strong, the oil well is flooded, and the wellhead pressure reaches 8MPa;

[0038] Step 1: During the water injection well profile control stage, firstly perform three-level water plugging and profile control on the water flow advantage channel formed by the previous water injection, and then use clean water to displace the water plugging agent in the wellbore and enter the formation;

[0039] Specifically, during the water injection well profile adjustment stage, the injection rate is 1.7m 3 / h2800m 3 The nano-scale microspheres are injected into the water flow advantage channel formed by the previous water injection, and then the injection displacement is 1.8m 3 / h1800m 3 PEG gel particles were injected into the water flow dominant channel formed by the previous water injection, and then the injection displacement was 1.5m 3 / h 50m 3 The weak phenolic resin gel was injected into the water flow dominant channel formed by the early water injection, and finally 3 / h construction displacement using 5m 3 Clean water displaces the water plugging agent in the wellbore and enters the formation.

[0040] Step 2: After the water injection well profile adjustment is completed, the wellhead pressure of the oil well is monitored;

[0041] Step 3: When the wellhead pressure of the oil well drops to 3.5MPa, start plugging the oil well. Since the oil wells have been fractured, the oil layer near the wellbore forms a dual-medium seepage characteristic of fracture-pore, with fracture seepage as the main flow and pore seepage as the auxiliary flow. First, transport the three-stage plugging water-blocking agent to the deep bedrock pores of the formation through the fractured fractures, and then use cross-linked guar gum to displace the water-blocking agent in the fractured fractures into the matrix micro-fractures, shut down the well and solidify, and complete the construction;

[0042] Furthermore, the three-stage plugging agent includes nano-scale microspheres, PEG gel particle profile control, and a mixed plugging agent, and the mixed plugging agent is a mixture of phenolic resin gel and quartz sand particles (40-70 mesh) in a volume ratio of 8.3:2.

[0043] Specifically, firstly, the fracture is 0.5m 3 / min200m 3 Microspheres are injected into the water channel to block the matrix pores, and then the fractures are fractured to 0.4m 3 / min180m 3 Gel particles are injected into the water channel to block the micro cracks, and then the fractures are fractured with a 0.6m 3 / min380m 3 The mixed water plugging agent was injected into the water channel to plug the water cracks. Finally, 80m 3 Cross-linked guar gum with a content of less than 0.5 μm 3 / min construction displacement will displace the water plugging agent in the artificial fractures into the matrix micro-fractures, leaving artificial fractures as channels for later fluid production. The well will be shut down and solidified for 72 hours to end the entire construction.

[0044] In May 2019, the oil and water wells were plugged in accordance with this embodiment, and an effective displacement system was re-established. In the initial stage (the first 3 months), the water content of the oil wells decreased by an average of 64%, and the daily oil production increased by an average of 1.3 tons / day. The water plugging period is still valid for 26 months as of now (July 2021).

[0045] Example 3

[0046] In this embodiment, the oil well is of pore-fracture type with water breakthrough, the water crossover between oil and water wells is strong, the oil well is flooded, and the wellhead pressure reaches 8.8MPa;

[0047] Step 1: During the water injection well profile control stage, firstly perform three-level water plugging and profile control on the water flow advantage channel formed by the previous water injection, and then use clean water to displace the water plugging agent in the wellbore and enter the formation;

[0048] Specifically, during the water injection well profile adjustment stage, the injection displacement is 1.3m 3 / h3000m 3 The nano-scale microspheres are injected into the water flow advantage channel formed by the previous water injection, and then the injection displacement is 1.7m 3 / h2100m 3 PEG gel particles were injected into the water flow dominant channel formed by the previous water injection, and then the injection displacement was 1.9m 3 / h100m 3 The weak phenolic resin gel was injected into the water flow dominant channel formed by the early water injection, and finally 3 / h construction displacement using 8m 3 Clean water displaces the water plugging agent in the wellbore and enters the formation.

[0049] Step 2: After the water injection well profile adjustment is completed, the wellhead pressure of the oil well is monitored;

[0050] Step 3: When the wellhead pressure of the oil well drops to 3.6MPa, start plugging the oil well. Since the oil wells have been fractured, the oil layer near the wellbore forms a dual-medium seepage characteristic of fracture-pore, with fracture seepage as the main flow and pore seepage as the auxiliary flow. First, transport the three-stage plugging water-blocking agent to the deep bedrock pores of the formation through the fractured fractures, and then use cross-linked guar gum to displace the water-blocking agent in the fractured fractures into the matrix micro-fractures, shut down the well and solidify, and complete the construction;

[0051] Furthermore, the three-stage plugging agent includes nano-scale microspheres, PEG gel particle profile control, and a mixed plugging agent, and the mixed plugging agent is a mixture of phenolic resin gel and quartz sand particles (40-70 mesh) in a volume ratio of 8.2:2.

[0052] Specifically, firstly, the fracture is 0.5m 3 / min200m 3 Microspheres are injected into the water channel to block the matrix pores, and then the fractures are fractured to 0.4m 3 / min150m 3 Gel particles were injected into the water channel to block the micro cracks, and then the fractures were fractured with a 0.7m 3 / min360m 3 The mixed water plugging agent was injected into the water channel to plug the water cracks. Finally, 90m 3 Cross-linked guar gum with a content of less than 0.5 μm 3 / min construction displacement will displace the water plugging agent in the artificial fractures into the matrix micro-fractures, leaving artificial fractures as channels for later fluid production. The well will be shut down and solidified for 72 hours to end the entire construction.

[0053] In January 2019, the oil and water wells were plugged in accordance with this embodiment, and an effective displacement system was re-established. In the initial stage (the first 3 months), the water content of the oil wells decreased by an average of 55%, and the daily oil production increased by an average of 1.3 tons / day. The water plugging period is still valid for 30 months as of now (July 2021).

[0054] Example 4

[0055] In this embodiment, the oil well is of pore-fracture type with water breakthrough, the water crossover between oil and water wells is strong, the oil well is flooded, and the wellhead pressure reaches 9.3MPa;

[0056] Step 1: During the water injection well profile control stage, firstly perform three-level water plugging and profile control on the water flow advantage channel formed by the previous water injection, and then use clean water to displace the water plugging agent in the wellbore and enter the formation;

[0057] Specifically, during the water injection well profile adjustment stage, the injection rate is 1.6m 3 / h3000m 3 The nano-scale microspheres are injected into the water flow advantage channel formed by the previous water injection, and then the injection displacement is 1.5m 3 / h1900m 3 PEG gel particles were injected into the water flow dominant channel formed by the previous water injection, and then the injection displacement was 1.3m 3 / h70m 3 Phenolic resin weak gel is injected into the water flow dominant channel formed by the early water injection, and finally the water flow is less than 3m 3 / h construction displacement using 6.5m 3 Clean water displaces the water plugging agent in the wellbore and enters the formation.

[0058] Step 2: After the water injection well profile adjustment is completed, the wellhead pressure of the oil well is monitored;

[0059] Step 3: When the wellhead pressure of the oil well drops to 4.0MPa, start plugging the oil well. Since the oil wells have been fractured, the oil layer near the wellbore area forms a dual-medium seepage characteristic of fracture-pore, with fracture seepage as the main flow and pore seepage as the auxiliary flow. First, the three-stage plugging water-blocking agent is transported to the deep bedrock pores of the formation through the fractured fractures, and then the cross-linked guar gum is used to displace the water-blocking agent in the fractured fractures into the matrix micro-fractures, and the well is shut down for solidification to complete the construction;

[0060] Furthermore, the three-stage plugging agent includes nano-scale microspheres, PEG gel particle profile control, and mixed plugging agent, and the mixed plugging agent is a mixture of phenolic resin gel and quartz sand particles (40-70 mesh) in a volume ratio of 8:2.

[0061] Specifically, firstly, the fracture is 0.5m 3 / min230m 3Microspheres are injected into the water channel to block the matrix pores, and then the fractures are fractured with a depth of 0.5 m. 3 / min220m 3 Gel particles are injected into the water channel to block the micro cracks, and then the fractures are fractured with a 0.6m 3 / min360m 3 The mixed water plugging agent was injected into the water channel to plug the water cracks. Finally, 85m 3 Cross-linked guar gum with a content of less than 0.5 μm 3 / min construction displacement will displace the water plugging agent in the artificial fractures into the matrix micro-fractures, leaving artificial fractures as channels for later fluid production. The well will be shut down and solidified for 72 hours to end the entire construction.

[0062] In April 2019, the oil and water wells were plugged in accordance with this embodiment, and an effective displacement system was re-established. In the initial stage (the first 3 months), the water content of the oil wells decreased by an average of 43%, and the daily oil production increased by an average of 1.3 tons / day. The water plugging period is still valid for 27 months as of now (July 2021).

Claims

1. A water plugging method for an oil and water well, characterized in that: The following steps are involved: Step 1: During the water injection well profile control stage, firstly perform three-level water plugging and profile control on the water flow advantage channel formed by the previous water injection, and then use clean water to displace the water plugging agent in the wellbore and enter the formation; Step 2: After the water injection well profile adjustment is completed, the wellhead pressure of the oil well is monitored; Step 3: When the wellhead pressure of the oil well is less than the preset pressure, the three-stage plugging water-blocking agent is first transported to the deep bedrock pores of the formation through the fracturing cracks, and then the water-blocking agent in the fracturing cracks is displaced into the matrix micro-cracks by cross-linked guar gum, and the well is shut down for solidification to complete the construction; The three-stage water plugging and profile control plugging process in step 1 is: using nano-scale microspheres, micron-scale PEG gel particles, and phenolic resin weak gel to grade and pump into the water flow dominant channel formed by the previous water injection; The specific process of step 1 is as follows: In the water injection well profile adjustment stage, firstly inject 1.0-2.0m 3 / h2800-3200m 3 The nano-scale microspheres are injected into the water flow advantage channel formed by the early water injection, and then the injection displacement is 1.0-2.0m 3 / h1800-2100m 3 PEG gel particles are injected into the water flow advantage channel formed by the early water injection, and then the injection displacement is 1.0-2.0m 3 / h50-100m 3 Phenolic resin weak gel is injected into the water flow dominant channel formed by the early water injection, and finally the water flow is less than 3m 3 / h construction displacement using 5-8m 3 Clean water displaces the water plugging agent in the wellbore and enters the formation; The three-stage plugging agent in step 3 includes nano-scale microspheres, PEG gel particles, and a mixed plugging agent, wherein the mixed plugging agent is a mixture of phenolic resin gel and quartz sand particles; The volume ratio of phenolic resin gel to quartz sand particles in the mixed water plugging agent is 8-8.5:2; The preset pressure in step 3 is 5MPa; Step 3 is as follows: First, the fracture is 0.3-0.5m 3 200-250m / min 3 Nano-scale microspheres are injected into the water channel to block the matrix pores, and then the water is pumped through the fractures to form a 0.3-0.5m 3 200-250m / min 3 PEG gel particles are injected into the water channel to plug the micro cracks, and then the fractures are hydraulically fractured to form a 0.5-0.8m 3 300-400m / min 3 The mixed water plugging agent is injected into the water channel to plug the water cracks. Finally, the water plugging agent is less than 0.5m 3 The construction displacement will be 80-100m / min. 3 Cross-linked guar gum is used as a water plugging agent in cracks to displace and enter the micro-cracks of the matrix.