Carbon dioxide thickening fracturing system and technological method thereof
阅读说明：本技术 一种二氧化碳增稠压裂系统及其工艺方法 (Carbon dioxide thickening fracturing system and technological method thereof ) 是由 袁彦峰 李秋昕 李明 逯瑞晓 王甜 郑焰 于 2021-10-18 设计创作，主要内容包括：本发明适用于压裂改造领域,提供了一种二氧化碳增稠压裂系统,包括输出系统、压裂液处理系统以及液态CO-(2)处理系统：所述压裂液处理系统包括：液态CO-(2)增稠剂原液处理系统以及压裂液增稠系统；工艺方法步骤如下：1)伸缩短接21、安全接头23、低温高压气密封水力锚24、低温高压气密封锚定式封隔器25、喷砂嘴26与压裂完井油管22一起通过修井机械下入井内,本发明通过压裂液、液态二氧化碳泵注程序设计,实现了液态二氧化碳的增稠、增稠液态二氧化碳造缝、增稠液态二氧化碳与液体共同携砂等,能够有效减少液体对储层的影响,提高返排率,最大限度保证储层改造效果,提高单井产量。(The invention is suitable for the field of fracturing modification, and provides a carbon dioxide thickening fracturing system which comprises an output system, a fracturing fluid treatment system and liquid CO 2 The processing system comprises: the fracturing fluid treatment system comprises: liquid CO 2 A thickener stock solution treatment system and a fracturing fluid thickening system; the process method comprises the following steps: 1) the flexible short joint 21, the safety joint 23, the low-temperature high-pressure air-tight seal hydraulic anchor 24, the low-temperature high-pressure air-tight seal anchor type packer 25, the sand blasting nozzle 26 and the fracturing well completion oil pipe 22 are put into the well together through a well workover rig, and the invention realizes the thickening of liquid carbon dioxide, the crack formation of thickened liquid carbon dioxide and the thickening of thickened liquid carbon dioxide through the pumping program design of fracturing fluid and liquid carbon dioxideThe carbon oxide and the liquid carry sand and the like together, so that the influence of the liquid on the reservoir can be effectively reduced, the flowback rate is improved, the reservoir transformation effect is ensured to the maximum extent, and the single-well yield is improved.)
1. The carbon dioxide thickening fracturing system is characterized by comprising an output system, a fracturing fluid treatment system and liquid CO2The processing system comprises:
the fracturing fluid treatment system comprises: liquid CO2A thickener stock solution treatment system and a fracturing fluid thickening system;
liquid CO2The thickener stock solution treatment system comprises: liquid CO2Thickener stock tank, CO2The system comprises a thickener solution preparation tank, a water storage tank, a sand mixing and liquid supply vehicle, a liquid high-pressure pump vehicle and a fracturing fluid wellhead injection head; the liquid high-pressure pump truck is connected with the output system through a normal-temperature high-pressure pipeline, the liquid high-pressure pump truck is connected with the sand mulling and liquid supply truck through a medium-pressure normal-temperature pipeline, and the sand mulling and liquid supply truck is connected with the CO through a low-pressure normal-temperature pipeline2Thickener solution preparation tank connection, CO2The thickener solution preparation tank is communicated with liquid CO through a low-pressure normal-temperature pipeline2The thickener solution preparation tank is connected with a water storage tank through a low-pressure normal-temperature pipeline, and the water storage tank is connected with the sand mulling liquid supply vehicle through a low-pressure normal-temperature pipeline;
the fracturing fluid thickening system is connected with the sand mulling and liquid supplying vehicle, and liquid CO is used2The processing system is connected with one end part of the output system.
2. The carbon dioxide thickened fracturing system of claim 1, wherein the output system comprises: the method comprises the following steps of producing a casing, a telescopic short joint, a fracturing well completion oil pipe, a safety joint low-temperature high-pressure air-tight seal hydraulic anchor, a low-temperature high-pressure air-tight seal anchor type packer, a sand blasting nozzle, a reservoir crack, an injection wellhead and a perforation hole; the fracturing well completion oil pipe is connected with the fracturing well completion oil pipe through the telescopic short joint, the safety joint, the low-temperature high-pressure air-tight hydraulic anchor, the low-temperature high-pressure air-tight anchor type packer and the sand blasting nozzle, the perforation hole is formed in the production casing pipe, the fracturing fluid well head injection head is installed on the injection well head, and the fracturing fluid well head injection head is connected with the normal-temperature high-pressure pipeline.
3. The carbon dioxide-thickened fracturing system of claim 1, wherein the fracturing fluid thickening system comprises: a fracturing proppant storage tank and a fracturing fluid thickener stock solution storage tank; the fracturing propping agent storage tank is connected with a propping agent delivery pipeline, the propping agent delivery pipeline is connected with a sand mixing and liquid supply vehicle, and the fracturing fluid thickening agent stock solution storage tank is connected with the sand mixing and liquid supply vehicle through a low-pressure normal-temperature pipeline.
4. The carbon dioxide thickened fracturing system of claim 2, wherein the liquid CO is2The processing system comprises: the system comprises a liquid carbon dioxide storage tank, a low-temperature pipeline, a carbon dioxide booster pump, a medium-pressure low-temperature pipeline, a liquid carbon dioxide high-pressure pump truck, a low-temperature high-pressure pipeline and a liquid carbon dioxide wellhead injection head; the liquid carbon dioxide storage tank is connected with the carbon dioxide booster pump through a low-temperature pipeline, the carbon dioxide booster pump is connected with the liquid carbon dioxide high-pressure pump truck through a medium-pressure low-temperature pipeline, the liquid carbon dioxide high-pressure pump truck is connected with the liquid carbon dioxide wellhead injection head through a low-temperature high-pressure pipeline, and the liquid carbon dioxide wellhead injection head is connected with the injection wellhead.
5. The carbon dioxide thickened fracturing system of claim 2, wherein the liquid carbon dioxide wellhead injector head is flanged to the injection wellhead, and the fracturing fluid wellhead injector head is flanged to the injection wellhead.
6. The carbon dioxide thickening and fracturing system of claim 2, wherein the telescopic pup joint, the safety joint, the low-temperature high-pressure gas-tight hydraulic anchor, the low-temperature high-pressure gas-tight seal anchor type packer and the sand blasting nozzle are respectively connected with the fracturing completion oil pipe in a threaded manner.
7. The carbon dioxide thickening and fracturing process method as claimed in any one of claims 1 to 6, characterized by comprising the following steps:
1) the low-temperature high-pressure airtight sealed anchoring packer is set and started in a manner of rotating the fracturing well completion oil pipe, and the anchoring machine is in contact with the inner wall of the production casing and is anchored;
2) liquid CO2CO in thickener stock solution tank2The concentration of thickener stock solution is 80-90%, and CO is2The thickener stock solution is conveyed to CO through a low-pressure normal-temperature pipeline2Thickener solution preparation tank, water storage tank is conveyed to CO through low-pressure normal-temperature pipeline2Thickener solution preparation tank, CO2In the presence of CO from thickener stock solution and water2Thickener solution preparation tank mixing, CO2Diluting the thickener stock solution to 12-17% concentration, and CO2The thickener solution preparation tank is used for diluting 12-17% CO by a low-pressure normal-temperature pipeline2Conveying the thickener solution to a sand mixing and liquid supply vehicle, conveying water to the sand mixing and liquid supply vehicle by a water storage tank through a low-pressure normal-temperature pipeline, and conveying CO2The thickener solution is mixed with water in a sand mulling and watering vehicle, where CO is formed2CO with 1-1.5% concentration of thickener solution2A thickener solution;
3) the fracturing fluid thickener stock solution storage tank conveys the fracturing fluid thickener to a sand mixing liquid supply vehicle through a low-pressure normal-temperature pipeline, and the fracturing fluid thickener and 1-1.5 percent CO are mixed2Mixing the thickening agent solutions to form fracturing fluid with the concentration of the thickening agent of the fracturing fluid of 0.4-0.8%, wherein the viscosity of the fracturing fluid is 40-60 mPa.S;
4) mixing sand and supplying CO by liquid vehicle2Pressurizing the mixed solution with the thickening agent concentration of 1-1.5% and the fracturing fluid thickening agent concentration of 0.4-0.8% to 0.5-0.8MPa, and then conveying the mixed solution to a liquid high-pressure pump truck through a medium-pressure normal-temperature pipeline, wherein the liquid high-pressure pump truck conveys CO to the liquid high-pressure pump truck2Pressurizing the fracturing fluid with the thickening agent concentration of 1-1.5% and the fracturing fluid thickening agent concentration of 0.4-0.8% to 50-65MPa, and conveying the fracturing fluid to a fracturing fluid wellhead injection head through a normal-temperature high-pressure pipeline;
5) the temperature in the liquid carbon dioxide storage tank is low between 35 ℃ below zero and 28 DEG CLow pressure liquid CO2Is conveyed to a carbon dioxide booster pump through a low-temperature pipeline, and the carbon dioxide booster pump is used for delivering low-temperature liquid CO2Pressurizing to 2.4-3.0MPa, and liquid CO2The temperature is increased to-20 to-16 ℃, and the liquid CO is pumped by a carbon dioxide booster pump2After pressurization, the liquid CO is conveyed to a liquid carbon dioxide high-pressure pump truck through a medium-pressure low-temperature pipeline, the pressure is 2.4-2.8MPa, and the temperature is minus 20 ℃ to minus 16 DEG C2After being pressurized to 50-65MPa by a liquid carbon dioxide high-pressure pump truck 5 and the temperature is raised to be above 0 ℃, the mixture is conveyed to a liquid carbon dioxide wellhead injection head by a low-temperature high-pressure pipeline;
6) the treated fracturing fluid in the step 4) and the liquid CO treated by the liquid carbon dioxide high-pressure pump truck 5 in the step 5)2Mixing at the injection well head 28, liquid CO during the mixing process2Extraction of CO from the mixed solution2Thickener, liquid CO2The viscosity is increased from 0.3 to 0.5mPa.S to 40m to 60mPa.S, and the discharge capacity of liquid carbon dioxide entering an injection well mouth from an injection head of the liquid carbon dioxide well mouth is 2.5 to 3 times of the discharge capacity of fracturing fluid entering the injection well mouth from the injection head of the fracturing fluid well mouth in the mixing process;
7) liquid CO2The mixed solution with the fracturing fluid is conveyed to a sand blasting nozzle in a fracturing well completion oil pipe, enters a production casing and then enters a reservoir through perforation holes to form reservoir cracks;
8) the fracturing propping agent storage tank conveys the fracturing propping agent to a sand mixing and liquid supply vehicle and liquid CO through a propping agent conveying pipeline2Mixing the mixed liquid phase of the fracturing fluid, and then obtaining liquid CO2The viscosity of the fracturing fluid reaches 40-60mPa.S after being thickened, and the fracturing fluid can effectively carry fracturing propping agent, fracturing fluid and liquid CO2Conveyed to a sand blasting nozzle through a fracturing well completion oil pipe, enters a production casing, then enters a reservoir stratum crack through a perforation hole, and fracturing fluid and liquid CO2The fluid loss enters the reservoir, and the proppant is left in the reservoir fractures to prop the fractures, so that the fracture morphology is kept in an open state all the time.
Technical Field
The invention belongs to the field of fracturing modification, and particularly relates to a carbon dioxide thickening fracturing system and a process method thereof.
Background
The fracturing modification technology is the most direct and effective method for improving the recovery ratio and the single-well yield. A large number of field tests and applications have been carried out in the oil and gas industry for many years, and various process methods for improving the fracturing improvement effect have been developed. CO22The fracturing process is characterized in that on the basis of the traditional fracturing process, water-based fracturing fluid is replaced by liquid CO2Mainly by liquid CO2The purpose of reservoir reconstruction is achieved by making seams and carrying sand.
Chinese patent CN110761764A discloses a liquid carbon dioxide fracturing method, which aims at dry CO2The optimal design of the fracturing process is carried out, and the problem is not related to CO2The content of the performance of the device;
chinese patent 2019100482187 (application number) and CN109736767A (publication number) relate to a supercritical carbon dioxide fracturing production-increasing process, and the invention is CO2Purely dry fracturing, i.e. with liquid CO only during fracturing2Without reference to water-based fracturing fluids;
chinese patent CN108864387B provides a drag reducer for carbon dioxide dry fracturing and its application, and the patent is a drag reducer developed for carbon dioxide dry fracturing, is an optimization of liquid carbon dioxide, and does not relate to a related process method combining water base and liquid carbon dioxide.
Disclosure of Invention
The invention aims to provide a carbon dioxide thickening fracturing system and a process method thereof, and aims to solve the problem that conventional liquid carbon dioxide cannot normally form cracks in a reservoir.
The invention is realized in such a way that a carbon dioxide thickening fracturing system comprises an output system, a fracturing fluid treatment system and liquid CO2The processing system comprises:
the fracturing fluid treatment system comprises: liquid stateCO2A thickener stock solution treatment system and a fracturing fluid thickening system;
liquid CO2The thickener stock solution treatment system comprises: liquid CO2Thickener stock tank 18, CO2The system comprises a thickener solution preparation tank, a water storage tank, a sand mixing and liquid supply vehicle, a liquid high-pressure pump vehicle and a fracturing fluid wellhead injection head; the liquid high-pressure pump truck is connected with the output system through a normal-temperature high-pressure pipeline, the liquid high-pressure pump truck is connected with the sand mulling and liquid supply truck through a medium-pressure normal-temperature pipeline, and the sand mulling and liquid supply truck is connected with the CO through a low-pressure normal-temperature pipeline2Thickener solution preparation tank connection, CO2The thickener solution preparation tank is communicated with liquid CO through a low-pressure normal-temperature pipeline2The thickener solution preparation tank is connected with a water storage tank through a low-pressure normal-temperature pipeline, and the water storage tank is connected with the sand mulling liquid supply vehicle through a low-pressure normal-temperature pipeline;
the fracturing fluid thickening system is connected with the sand mulling and liquid supplying vehicle, and liquid CO is used2The processing system is connected with one end part of the output system.
In a further aspect, the output system includes: the method comprises the following steps of producing a casing, a telescopic short joint, a fracturing well completion oil pipe, a safety joint low-temperature high-pressure air-tight seal hydraulic anchor, a low-temperature high-pressure air-tight seal anchor type packer, a sand blasting nozzle, a reservoir crack, an injection wellhead and a perforation hole; the fracturing well completion oil pipe is connected with the fracturing well completion oil pipe through the telescopic short joint, the safety joint, the low-temperature high-pressure air-tight hydraulic anchor, the low-temperature high-pressure air-tight anchor type packer and the sand blasting nozzle, the perforation hole is formed in the production casing pipe, the fracturing fluid well head injection head is installed on the injection well head, and the fracturing fluid well head injection head is connected with the normal-temperature high-pressure pipeline.
According to a further technical scheme, the fracturing fluid thickening system comprises: a fracturing proppant storage tank and a fracturing fluid thickener stock solution storage tank; the fracturing propping agent storage tank is connected with a propping agent delivery pipeline, the propping agent delivery pipeline is connected with a sand mixing and liquid supply vehicle, and the fracturing fluid thickening agent stock solution storage tank is connected with the sand mixing and liquid supply vehicle through a low-pressure normal-temperature pipeline.
In a further aspect, the liquid CO is2The processing system comprises: liquid carbon dioxide storage tankThe system comprises a low-temperature pipeline, a carbon dioxide booster pump, a medium-pressure low-temperature pipeline, a liquid carbon dioxide high-pressure pump truck, a low-temperature high-pressure pipeline and a liquid carbon dioxide wellhead injection head; the liquid carbon dioxide storage tank is connected with the carbon dioxide booster pump through a low-temperature pipeline, the carbon dioxide booster pump is connected with the liquid carbon dioxide high-pressure pump truck through a medium-pressure low-temperature pipeline, the liquid carbon dioxide high-pressure pump truck is connected with the liquid carbon dioxide wellhead injection head through a low-temperature high-pressure pipeline, and the liquid carbon dioxide wellhead injection head is connected with the injection wellhead.
According to the technical scheme, the liquid carbon dioxide wellhead injection head is installed on the injection wellhead in a flange mode, and the fracturing fluid wellhead injection head is connected with the injection wellhead in a flange mode.
According to a further technical scheme, the telescopic short joint, the safety joint, the low-temperature high-pressure air-tight seal hydraulic anchor, the low-temperature high-pressure air-tight seal anchor type packer and the sand blasting nozzle are connected with a fracturing well completion oil pipe in a threaded mode respectively.
A carbon dioxide thickening and fracturing process method comprises the following steps:
1) the low-temperature high-pressure airtight sealed anchoring packer is set and started in a manner of rotating the fracturing well completion oil pipe, and the anchoring machine is in contact with the inner wall of the production casing and is anchored;
2) liquid CO2CO in thickener stock solution tank2The concentration of thickener stock solution is 80-90%, and CO is2The thickener stock solution is conveyed to a CO thickener solution preparation tank through a low-pressure normal-temperature pipeline, and the water storage tank is conveyed to CO through a low-pressure normal-temperature pipeline2Thickener solution preparation tank, CO2In the presence of CO from thickener stock solution and water2Thickener solution preparation tank mixing, CO2Diluting the thickener stock solution to 12-17% concentration, and CO2The thickener solution preparation tank is used for diluting 12-17% CO by a low-pressure normal-temperature pipeline2The thickener solution is conveyed to a sand mixing and liquid supplying vehicle, and the water storage tank conveys water to sand mixing and liquid supplying vehicle through a low-pressure normal-temperature pipelineLiquid vehicle, CO2The thickener solution is mixed with water in a sand mulling and watering vehicle, where CO is formed2CO with 1-1.5% concentration of thickener solution2A thickener solution;
3) the fracturing fluid thickener stock solution storage tank conveys the fracturing fluid thickener to a sand mixing liquid supply vehicle through a low-pressure normal-temperature pipeline, and the fracturing fluid thickener and 1-1.5 percent CO are mixed2Mixing the thickening agent solutions to form fracturing fluid with the concentration of the thickening agent of the fracturing fluid of 0.4-0.8%, wherein the viscosity of the fracturing fluid is 40-60 mPa.S;
4) mixing sand and supplying CO by liquid vehicle2Pressurizing the mixed solution with the thickening agent concentration of 1-1.5% and the fracturing fluid thickening agent concentration of 0.4-0.8% to 0.5-0.8MPa, and then conveying the mixed solution to a liquid high-pressure pump truck through a medium-pressure normal-temperature pipeline, wherein the liquid high-pressure pump truck conveys CO to the liquid high-pressure pump truck2Pressurizing the fracturing fluid with the thickening agent concentration of 1-1.5% and the fracturing fluid thickening agent concentration of 0.4-0.8% to 50-65MPa, and conveying the fracturing fluid to a fracturing fluid wellhead injection head through a normal-temperature high-pressure pipeline;
5) low-temperature low-pressure liquid CO with the temperature of-35 to-28 ℃ in the liquid carbon dioxide storage tank2Is conveyed to a carbon dioxide booster pump through a low-temperature pipeline, and the carbon dioxide booster pump is used for delivering low-temperature liquid CO2Pressurizing to 2.4-3.0MPa, and liquid CO2The temperature is increased to-20 to-16 ℃, and the liquid CO is pumped by a carbon dioxide booster pump2After pressurization, the liquid CO is conveyed to a liquid carbon dioxide high-pressure pump truck through a medium-pressure low-temperature pipeline, the pressure is 2.4-2.8MPa, and the temperature is minus 20 ℃ to minus 16 DEG C2After being pressurized to 50-65MPa by a liquid carbon dioxide high-pressure pump truck and the temperature is raised to be above 0 ℃, the mixture is conveyed to a liquid carbon dioxide wellhead injection head through a low-temperature high-pressure pipeline;
6) the treated fracturing fluid in the step 4) and the liquid CO treated by the liquid carbon dioxide high-pressure pump truck 5 in the step 5)2Mixing at the injection well head 28, liquid CO during the mixing process2Extraction of CO from the mixed solution2Thickener, liquid CO2The viscosity is increased from 0.3 to 0.5mPa.S to 40m to 60mPa.S, and the discharge capacity of liquid carbon dioxide entering an injection well mouth from an injection head of the liquid carbon dioxide well mouth is 2.5 to 3 times of the discharge capacity of fracturing fluid entering the injection well mouth from the injection head of the fracturing fluid well mouth in the mixing process;
7) liquid CO2The mixed solution with the fracturing fluid is conveyed to a sand blasting nozzle 26 in a fracturing completion oil pipe 22, enters a production casing 20 and then enters a reservoir through a perforation hole 31 to form a reservoir fracture 27;
8) the fracturing propping agent storage tank conveys the fracturing propping agent to a sand mixing and liquid supply vehicle and liquid CO through a propping agent conveying pipeline2Mixing the mixed liquid phase of the fracturing fluid, and then obtaining liquid CO2The viscosity of the fracturing fluid reaches 40-60mPa.S after being thickened, and the fracturing fluid can effectively carry fracturing propping agent, fracturing fluid and liquid CO2Conveyed to a sand blasting nozzle through a fracturing well completion oil pipe, enters a production casing, then enters a reservoir stratum crack through a perforation hole, and fracturing fluid and liquid CO2The fluid loss enters the reservoir, and the proppant is left in the reservoir fractures to prop the fractures, so that the fracture morphology is kept in an open state all the time.
Compared with the prior art, the invention has the following beneficial effects:
according to the invention, through the design of a fracturing fluid and a liquid carbon dioxide pumping program, the thickening of the liquid carbon dioxide, the crack formation of the thickened liquid carbon dioxide, the sand carrying of the thickened liquid carbon dioxide and the liquid are realized, the phase change of the liquid carbon dioxide from liquid to gas in a reservoir is generated in the flowback process, the injected fracturing is completely replaced out of the ground, the influence of the liquid on the reservoir is effectively reduced, the flowback rate is improved, the reservoir transformation effect is ensured to the maximum extent, and the single well yield is improved.
Drawings
Fig. 1 is a schematic diagram of the connection between the system structures in one embodiment of the present invention.
Notations for reference numerals: the system comprises a liquid carbon dioxide storage tank 1, a low-temperature pipeline 2, a carbon dioxide booster pump 3, a medium-pressure low-temperature pipeline 4, a liquid carbon dioxide high-pressure pump truck 5, a low-temperature high-pressure pipeline 6, a liquid carbon dioxide wellhead injection head 7, a fracturing fluid wellhead injection head 8, a normal-temperature high-pressure pipeline 9, a liquid high-pressure pump truck 10, a medium-pressure normal-temperature pipeline 11, a sand mixing and liquid supply truck 12, a low-pressure normal-temperature pipeline 13, a thickening agent solution preparation tank 14CO2, a liquid CO2 thickening raw liquid agent tank 19, a water storage tank 19, a production casing 20, a telescopic short circuit 21, a fracturing well completion oil pipe 22, a safety joint 23, a low-temperature high-pressure gas sealing hydraulic anchor 24, a low-temperature high-pressure gas sealing and anchoring type packer 25, a sand blasting nozzle 26, a reservoir crack 27, a reservoir crack 28 injection wellhead 30, a fracturing fluid thickening agent raw liquid storage tank 31, a perforation 32, a fracturing propping agent storage tank 32 and a propping agent conveying pipeline 33.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described in detail with reference to the accompanying drawings and the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Specific implementations of the present invention are described in detail below with reference to specific embodiments.
Embodiment 1, a carbon dioxide thickening fracturing process, comprising the steps of:
1) the low-temperature high-pressure airtight sealed anchoring type packer 25 and the fracturing completion oil pipe 22 are put into a well together through a workover rig, the low-temperature high-pressure airtight sealed anchoring type packer 25 is set and started in a manner of rotating the fracturing completion oil pipe 22, and the anchoring rig is in contact with and anchored to the inner wall of the production casing 20;
the sealing element is tightly attached to the inner wall of the production casing pipe 20 to play a role of sealing, and the low-temperature high-pressure gas-tight sealing hydraulic anchor enters high-pressure fracturing fluid and liquid CO when entering the oil pipe 242Is started, contacts and anchors the inner wall of the production casing 20, and is cooled to a low temperature to form liquid CO2After entering the fracturing completion oil pipe 22, the fracturing completion oil pipe 22 contracts due to the change of temperature, and the telescopic short joint 21 is opened and then extends to make up the contraction distance generated by the fracturing completion oil pipe 22, so that the safety of the pipe column is ensured;
2) liquid CO2CO in thickener stock solution tank2The concentration of the thickener stock solution is 80 percent, and CO is2The thickener stock solution is conveyed to CO through a low-pressure normal-temperature pipeline 132Thickener solution preparation tank 14, water storage tank 19 is transported to CO through low-pressure normal-temperature pipeline 132Thickener solution preparation tank 14, CO2Thickener stock solution andwater in CO2Thickener solution preparation tank 14 mixing, CO2The concentration of the thickener stock solution is diluted to 12 percent, and CO is added2A thickener solution preparation tank 14 for diluting 12% CO by a low-pressure normal-temperature pipeline 132The thickener solution is conveyed to a sand mixing and liquid supply vehicle 12, a water storage tank 19 conveys water to the sand mixing and liquid supply vehicle 12 through a low-pressure normal-temperature pipeline 13, CO2The thickener solution is mixed with water in the fracturing blender feed truck 12, where CO is formed21% strength CO in thickener solution2A thickener solution;
3) the fracturing fluid thickener stock solution storage tank 30 conveys the fracturing fluid thickener to the sand mixing and liquid supply vehicle 12 through a low-pressure normal-temperature pipeline 13, and the fracturing fluid thickener and 1% CO are mixed2Mixing the thickening agent solutions to form fracturing fluid with the concentration of the thickening agent of the fracturing fluid being 0.4%, wherein the viscosity of the fracturing fluid is 40 mPa.S;
4) mixing and supplying CO by the vehicle 122After the mixed solution with the thickening agent concentration of 1% and the fracturing fluid thickening agent concentration of 0.4% is pressurized to 0.5MPa, the mixed solution is conveyed to a liquid high-pressure pump truck 10 through a medium-pressure normal-temperature pipeline 11, and the liquid high-pressure pump truck 10 is used for delivering CO2After the fracturing fluid with the thickening agent concentration of 1% and the fracturing fluid thickening agent concentration of 0.4% is pressurized to 50MPa, the fracturing fluid is conveyed to a fracturing fluid wellhead injection head 8 through a normal-temperature high-pressure pipeline 9;
5) low-temperature low-pressure liquid CO with the temperature of minus 35 ℃ in the liquid carbon dioxide storage tank 12Is conveyed to a carbon dioxide booster pump 3 through a low-temperature pipeline 2, and the carbon dioxide booster pump 3 pumps low-temperature liquid CO2Pressurizing to 2.4MPa and obtaining liquid CO2The temperature is increased to-20 ℃, and the carbon dioxide booster pump 3 pumps the liquid CO2After pressurization, the liquid CO is conveyed to a liquid carbon dioxide high-pressure pump truck 5 through a medium-pressure low-temperature pipeline 4, the pressure of the liquid CO is 2.4MPa, and the temperature of the liquid CO is minus 20 DEG C2After being pressurized to 50MPa by a liquid carbon dioxide high-pressure pump truck 5 and the temperature is raised to be more than 0 ℃, the mixture is conveyed to a liquid carbon dioxide wellhead injection head 7 by a low-temperature high-pressure pipeline 6;
6) the treated fracturing fluid in the step 4) and the liquid CO treated by the liquid carbon dioxide high-pressure pump truck 5 in the step 5)2Mixing at the injection well head 28, liquid CO during the mixing process2Extraction of CO from the mixed solution2Thickener, liquid CO2The viscosity is increased from 0.3mPa.S to 40mPa.S, and in the mixing process, the discharge capacity of liquid carbon dioxide entering the injection well mouth 28 from the liquid carbon dioxide well mouth injection head 7 is 2.5-3 times of the discharge capacity of fracturing fluid entering the injection well mouth 28 from the fracturing fluid well mouth injection head 8;
7) liquid CO2The mixed solution with the fracturing fluid is conveyed to a sand blasting nozzle 26 in a fracturing completion oil pipe 22, enters a production casing 20 and then enters a reservoir through a perforation hole 31 to form a reservoir fracture 27;
8) the fracturing propping agent storage tank 32 conveys the fracturing propping agent to the sand mixing and liquid supply vehicle 12 through a propping agent conveying pipeline 33 and liquid CO2Mixing the mixed liquid phase of the fracturing fluid, and then obtaining liquid CO2The viscosity of the fracturing fluid reaches 40mPa.S after being thickened, and the fracturing fluid can effectively carry fracturing propping agent, fracturing fluid and liquid CO2Conveyed to a sand blasting nozzle 26 through a fracturing completion oil pipe 22, enters a production casing 20 and then enters reservoir cracks 27 through perforation holes 31, and fracturing fluid and liquid CO2The fluid loss enters the reservoir and proppant remains in the reservoir fractures 27, propping the fractures and keeping their fracture morphology open at all times.
Embodiment 2, a carbon dioxide thickening fracturing process, comprising the steps of:
1) the low-temperature high-pressure airtight sealed anchoring type packer 25 and the fracturing completion oil pipe 22 are put into a well together through a workover rig, the low-temperature high-pressure airtight sealed anchoring type packer 25 is set and started in a manner of rotating the fracturing completion oil pipe 22, and the anchoring rig is in contact with and anchored to the inner wall of the production casing 20;
the sealing element is tightly attached to the inner wall of the production casing pipe 20 to play a role of sealing, and the low-temperature high-pressure gas-tight sealing hydraulic anchor enters high-pressure fracturing fluid and liquid CO when entering the oil pipe 242Is started, contacts and anchors the inner wall of the production casing 20, and is cooled to a low temperature to form liquid CO2After entering the fractured completion tubing 22, the fractured completion tubing 22 will contract due to the temperature change, and the short joint 21 will open and extend to compensate the pressureThe shrinkage distance generated by the completion tubing 22 is cracked to ensure the safety of the tubing string;
2) liquid CO2CO in thickener stock solution tank2The concentration of the thickener stock solution is 85 percent, and CO is2The thickener stock solution is conveyed to CO through a low-pressure normal-temperature pipeline 132Thickener solution preparation tank 14, water storage tank 19 is transported to CO through low-pressure normal-temperature pipeline 132Thickener solution preparation tank 14, CO2In the presence of CO from thickener stock solution and water2Thickener solution preparation tank 14 mixing, CO2The concentration of the thickener stock solution is diluted to 15 percent, and CO is added2A thickener solution preparation tank 14 for diluting 15% CO by a low-pressure normal-temperature pipeline 132The thickener solution is conveyed to a sand mixing and liquid supply vehicle 12, a water storage tank 19 conveys water to the sand mixing and liquid supply vehicle 12 through a low-pressure normal-temperature pipeline 13, CO2The thickener solution is mixed with water in the fracturing blender feed truck 12, where CO is formed2CO with 1-1.5% concentration of thickener solution2A thickener solution;
3) the fracturing fluid thickener stock solution storage tank 30 conveys the fracturing fluid thickener to the sand mixing and liquid supply vehicle 12 through a low-pressure normal-temperature pipeline 13, and the fracturing fluid thickener and CO with the concentration of 1.2 percent2Mixing the thickening agent solutions to form fracturing fluid with the thickening agent concentration of 0.6%, wherein the viscosity of the fracturing fluid is 50 mPa.S;
4) mixing and supplying CO by the vehicle 122After the mixed solution with the thickening agent concentration of 1.2% and the fracturing fluid thickening agent concentration of 0.6% is pressurized to 0.6MPa, the mixed solution is conveyed to a liquid high-pressure pump truck 10 through a medium-pressure normal-temperature pipeline 11, and the liquid high-pressure pump truck 10 is used for delivering CO2After the fracturing fluid with the thickening agent concentration of 1.2% and the fracturing fluid thickening agent concentration of 0.6% is pressurized to 60MPa, the fracturing fluid is conveyed to a fracturing fluid wellhead injection head 8 through a normal-temperature high-pressure pipeline 9;
5) low-temperature low-pressure liquid CO with the temperature of-31 ℃ in the liquid carbon dioxide storage tank 12Is conveyed to a carbon dioxide booster pump 3 through a low-temperature pipeline 2, and the carbon dioxide booster pump 3 pumps low-temperature liquid CO2Pressurizing to 2.6MPa and obtaining liquid CO2The temperature is increased to-18 ℃, and the carbon dioxide booster pump 3 pumps the liquid CO2After being pressurized, the carbon dioxide is conveyed to a liquid carbon dioxide high-pressure pump truck 5 through a medium-pressure low-temperature pipeline 4, and the pressure is increasedLiquid CO at 2.6MPa and-18 DEG C2After being pressurized to 60MPa and the temperature is raised to be above 0 ℃ by a liquid carbon dioxide high-pressure pump truck 5, the mixture is conveyed to a liquid carbon dioxide wellhead injection head 7 by a low-temperature high-pressure pipeline 6;
6) the treated fracturing fluid in the step 4) and the liquid CO treated by the liquid carbon dioxide high-pressure pump truck 5 in the step 5)2Mixing at the injection well head 28, liquid CO during the mixing process2Extraction of CO from the mixed solution2Thickener, liquid CO2The viscosity is increased from 0.4mPa.S to 50mPa.S, and the discharge capacity of liquid carbon dioxide entering the injection well mouth 28 from the liquid carbon dioxide well mouth injection head 7 is 2.5-3 times of the discharge capacity of fracturing fluid entering the injection well mouth 28 from the fracturing fluid well mouth injection head 8 in the mixing process;
7) liquid CO2The mixed solution with the fracturing fluid is conveyed to a sand blasting nozzle 26 in a fracturing completion oil pipe 22, enters a production casing 20 and then enters a reservoir through a perforation hole 31 to form a reservoir fracture 27;
8) the fracturing propping agent storage tank 32 conveys the fracturing propping agent to the sand mixing and liquid supply vehicle 12 through a propping agent conveying pipeline 33 and liquid CO2Mixing the mixed liquid phase of the fracturing fluid, and then obtaining liquid CO2The viscosity of the fracturing fluid reaches 50mPa.S after being thickened, and the fracturing fluid can effectively carry fracturing propping agent, fracturing fluid and liquid CO2Conveyed to a sand blasting nozzle 26 through a fracturing completion oil pipe 22, enters a production casing 20 and then enters reservoir cracks 27 through perforation holes 31, and fracturing fluid and liquid CO2The fluid loss enters the reservoir and proppant remains in the reservoir fractures 27, propping the fractures and keeping their fracture morphology open at all times.
Embodiment 3, a carbon dioxide thickening fracturing process, comprising the steps of:
1) the low-temperature high-pressure airtight sealed anchoring type packer 25 and the fracturing completion oil pipe 22 are put into a well together through a workover rig, the low-temperature high-pressure airtight sealed anchoring type packer 25 is set and started in a manner of rotating the fracturing completion oil pipe 22, and the anchoring rig is in contact with and anchored to the inner wall of the production casing 20;
the sealing element is tightly attached to the inner wall of the production casing pipe 20 to play a role of sealing, and the low-temperature high-pressure gas-tight sealing hydraulic anchor enters high-pressure fracturing fluid and liquid CO when entering the oil pipe 242Is started, contacts and anchors the inner wall of the production casing 20, and is cooled to a low temperature to form liquid CO2After entering the fracturing completion oil pipe 22, the fracturing completion oil pipe 22 contracts due to the change of temperature, and the telescopic short joint 21 is opened and then extends to make up the contraction distance generated by the fracturing completion oil pipe 22, so that the safety of the pipe column is ensured;
2) liquid CO2CO in thickener stock solution tank2The concentration of the thickener stock solution is 90 percent, and CO is2The thickener stock solution is conveyed to CO through a low-pressure normal-temperature pipeline 132Thickener solution preparation tank 14, water storage tank 19 is transported to CO through low-pressure normal-temperature pipeline 132Thickener solution preparation tank 14, CO2In the presence of CO from thickener stock solution and water2Thickener solution preparation tank 14 mixing, CO2The concentration of the thickener stock solution is diluted to 17 percent, and CO is added2A thickener solution preparation tank 14 for diluting 17% CO by a low-pressure normal-temperature pipeline 132The thickener solution is conveyed to a sand mixing and liquid supply vehicle 12, a water storage tank 19 conveys water to the sand mixing and liquid supply vehicle 12 through a low-pressure normal-temperature pipeline 13, CO2The thickener solution is mixed with water in the fracturing blender feed truck 12, where CO is formed21.5% CO in thickener solution2A thickener solution;
3) the fracturing fluid thickener stock solution storage tank 30 conveys the fracturing fluid thickener to the sand mixing and liquid supply vehicle 12 through a low-pressure normal-temperature pipeline 13, and the fracturing fluid thickener and CO with the concentration of 1.5 percent2Mixing the thickening agent solutions to form fracturing fluid with the thickening agent concentration of 0.8%, wherein the viscosity of the fracturing fluid is 60 mPa.S;
4) mixing and supplying CO by the vehicle 122After the mixed solution with the thickening agent concentration of 1.5% and the fracturing fluid thickening agent concentration of 0.8% is pressurized to 0.8MPa, the mixed solution is conveyed to a liquid high-pressure pump truck 10 through a medium-pressure normal-temperature pipeline 11, and the liquid high-pressure pump truck 10 is used for delivering CO2After the fracturing fluid with the thickening agent concentration of 1.5 percent and the fracturing fluid thickening agent concentration of 0.8 percent is pressurized to 65MPa, the fracturing fluid is conveyed to the wellhead of the fracturing fluid through a normal-temperature high-pressure pipeline 9An injection head 8;
5) the low-temperature low-pressure liquid CO with the temperature of minus 35 to 28 ℃ in the liquid carbon dioxide storage tank 12Is conveyed to a carbon dioxide booster pump 3 through a low-temperature pipeline 2, and the carbon dioxide booster pump 3 pumps low-temperature liquid CO2Pressurizing to 3.0MPa and obtaining liquid CO2The temperature is increased to-16 ℃, and the carbon dioxide booster pump 3 pumps liquid CO2After pressurization, the liquid CO is conveyed to a liquid carbon dioxide high-pressure pump truck 5 through a medium-pressure low-temperature pipeline 4, the pressure of the liquid CO is 2.8MPa, and the temperature of the liquid CO is minus 16 DEG C2After being pressurized to 65MPa by a liquid carbon dioxide high-pressure pump truck 5 and the temperature is raised to be more than 0 ℃, the mixture is conveyed to a liquid carbon dioxide wellhead injection head 7 by a low-temperature high-pressure pipeline 6;
6) the treated fracturing fluid in the step 4) and the liquid CO treated by the liquid carbon dioxide high-pressure pump truck 5 in the step 5)2Mixing at the injection well head 28, liquid CO during the mixing process2Extraction of CO from the mixed solution2Thickener, liquid CO2The viscosity is increased from 0.5mPa.S to 60mPa.S, and the discharge capacity of the liquid carbon dioxide entering the injection well mouth 28 from the liquid carbon dioxide well mouth injection head 7 is 2.5-3 times of the discharge capacity of the fracturing fluid entering the injection well mouth 28 from the fracturing fluid well mouth injection head 8 in the mixing process;
7) liquid CO2The mixed solution with the fracturing fluid is conveyed to a sand blasting nozzle 26 in a fracturing completion oil pipe 22, enters a production casing 20 and then enters a reservoir through a perforation hole 31 to form a reservoir fracture 27;
8) the fracturing propping agent storage tank 32 conveys the fracturing propping agent to the sand mixing and liquid supply vehicle 12 through a propping agent conveying pipeline 33 and liquid CO2Mixing the mixed liquid phase of the fracturing fluid, and then obtaining liquid CO2The viscosity of the fracturing fluid reaches 60mPa.S after being thickened, and the fracturing fluid can effectively carry fracturing propping agent, fracturing fluid and liquid CO2Conveyed to a sand blasting nozzle 26 through a fracturing completion oil pipe 22, enters a production casing 20 and then enters reservoir cracks 27 through perforation holes 31, and fracturing fluid and liquid CO2The fluid loss enters the reservoir and proppant remains in the reservoir fractures 27, propping the fractures and keeping their fracture morphology open at all times.
The technical scheme for solving the problems is as follows:
1. designing a liquid carbon dioxide pressure thickening fracturing process and a pump injection program method: the fracturing process is divided into two pumping ends, wherein the first pumping end is a pumping end of conventional liquid, fracturing fluid and a carbon dioxide thickening agent are mainly pumped to a fracturing wellhead, mixed with liquid carbon dioxide and enter a reservoir stratum through a fracturing pipe column together, and meanwhile, sand-carrying fluid is pumped to carry fracturing propping agent to enter a fracture. And the second is a liquid carbon dioxide pumping end, which pumps the liquid carbon dioxide to a fracturing wellhead under pressure to be mixed with fracturing fluid and a carbon dioxide thickening agent. After mixing, the liquid carbon dioxide extracts thickening agent from the fracturing fluid, the viscosity of the thickening agent is increased, and the thickening agent and the fracturing fluid enter a reservoir stratum to form a seam together. In the proppant adding stage, the thickened liquid carbon dioxide and the fracturing fluid carry the proppant into the fracture together.
2. The design is adapted to the low-temperature and gas explosion-resistant thickened liquid carbon dioxide fracturing process pipe column, low temperature and gasification carbon dioxide erosion resistance are met, and meanwhile, the pipe column adopts a fixed structure, so that the creeping of the pipe column caused by the phase change of liquid carbon dioxide in the pump injection process is prevented.
According to the invention, through the design of a fracturing fluid and a liquid carbon dioxide pumping program, the thickening of the liquid carbon dioxide, the crack formation of the thickened liquid carbon dioxide, the sand carrying of the thickened liquid carbon dioxide and the liquid are realized, the phase change of the liquid carbon dioxide from liquid to gas in a reservoir is generated in the flowback process, the injected fracturing is completely replaced out of the ground, the influence of the liquid on the reservoir is effectively reduced, the flowback rate is improved, the reservoir transformation effect is ensured to the maximum extent, and the single well yield is improved.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.