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A liquefied petroleum gas-carbon dioxide water-enhanced composite fracturing method

A technology of liquefied petroleum gas and liquid carbon dioxide, which is applied in the direction of chemical instruments and methods, earthwork drilling and production, drilling compositions, etc., can solve the problems of tight oil and gas reservoir development, water sensitivity, water lock pollution, shale reservoir Pollution and other problems, to achieve the effect of reducing water lock effect, good fluidity, and ideal crack scale

Inactive Publication Date: 2019-10-22
CHINA UNIV OF PETROLEUM (BEIJING)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

To achieve this goal, high-volume injection of drag-reducing water fracturing fluid is usually used for fracturing operations, or carbon dioxide fracturing technology is used, but both processes have drawbacks
On the one hand, the use of drag-reducing water fracturing technology will cause a lot of waste of water resources, and at the same time, water-based liquids will cause water sensitivity and water lock pollution after entering the tiny pores, resulting in the closure of natural fractures, which will seriously damage the shale reservoir. bring permanent pollution
On the other hand, carbon dioxide fracturing fluid has low viscosity and poor sand-carrying effect, and a single carbon dioxide fracturing fluid cannot create main fractures with a certain length and width
It can be seen that the traditional fracturing method using a single working fluid has been unable to adapt to the development of tight oil and gas reservoirs.

Method used

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  • A liquefied petroleum gas-carbon dioxide water-enhanced composite fracturing method
  • A liquefied petroleum gas-carbon dioxide water-enhanced composite fracturing method
  • A liquefied petroleum gas-carbon dioxide water-enhanced composite fracturing method

Examples

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Effect test

Embodiment 1

[0036] This embodiment provides a liquefied petroleum gas-carbon dioxide anhydrous energized composite fracturing method. The working fluid used in this method is divided into liquefied petroleum gas fracturing fluid without proppant added, liquid carbon dioxide fracturing fluid without proppant There are four types of fracturing fluid, liquid carbon dioxide fracturing fluid carrying proppant and liquefied petroleum gas fracturing fluid carrying proppant.

[0037] Wherein, the composition of the liquefied petroleum gas fracturing fluid without proppant added is (based on the total weight of the fracturing fluid): 0.6% dialkyl phosphate viscosifier (the thickener can be low-carbon Hydrocarbon anhydrous fracturing fluid system and rheological properties research (Hou Xiangqian, East China University of Science and Technology master's degree thesis, 2014) product GA-14), 1.2% complex iron crosslinking agent (this crosslinking agent can be low carbon Hydrocarbon anhydrous fracturi...

Embodiment 2

[0050] This embodiment provides a liquefied petroleum gas-carbon dioxide water-free energized composite fracturing method, and the four working fluids used in this method are the same as those in Embodiment 1.

[0051] The method includes the following steps:

[0052] (1) Use nitrogen gas to check the tightness of the entire pipeline. After confirming that the pipeline is completely sealed, use liquefied petroleum gas fracturing fluid without proppant 3 Squeeze out the liquid in the wellbore to avoid polluting the formation;

[0053] (2) Inject liquefied petroleum gas fracturing fluid without proppant into the formation at an injection speed of 3.8-4.2m 3 / min, the injection pressure is controlled at 35~38MPa, and a total of 38m is injected 3 , make the reservoir rock hold pressure until it breaks, and produce main fractures with a certain width;

[0054] (3) Stop injecting liquefied petroleum gas fracturing fluid without proppant, and then inject liquid carbon dioxide frac...

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Abstract

The invention provides a composite fracturing method for liquefied petroleum gas (LPG)-carbon dioxide capacity increasing without water. The composite fracturing method comprises the following steps that LPG fracturing fluid is injected into a stratum, and injecting is stopped after a period of time; liquid carbon dioxide fracturing fluid is injected, and injecting is stopped after a period of time; the liquid carbon dioxide fracturing fluid carrying a propping agent is injected, and injecting is stopped after a period of time; and finally, the LPG fracturing fluid carrying the propping agentis injected, and injecting is stopped after a period of time. According to the composite fracturing method for LPG-carbon dioxide capacity increasing without the water, by injecting the different fracturing fluids at all injecting stages and reasonably utilizing the special properties of the different fracturing fluids, the effect of generating a fracture network is achieved, the oil-gas migrationcapacity of a fracture is improved, a vertical and horizontal 'netted fracture' system taking a main fracture as a main is formed, the well control area is increased, energy of the stratum is improved, the reservoir seepage characteristics are improved, the composite fracturing method is especially suitable for reservoirs with low permeability, compactness and high water sensitivity, the productivity after fracturing of a single well can be improved, and the problem that the low-permeability and compact reservoirs are poor in fracturing and reconstruction effect is solved.

Description

technical field [0001] The invention relates to an oil well fracturing process in the downhole operation technology of oil development, in particular to a liquefied petroleum gas-carbon dioxide water-free energy-increasing composite fracturing method, which belongs to the technical field of petroleum and natural gas. Background technique [0002] Shale reservoirs are tight, and there is almost no productivity without fracturing. Natural fractures exist in almost all low-permeability oil and gas reservoirs, but before these natural fractures are opened and connected with hydraulic fractures, they are rarely able to provide production. In shale gas reservoirs, primary fractures and secondary fractures exist at the same time, and can open and maintain permeability. Hydraulic fractures induce the activation of natural fractures to form large-scale connected network fractures, which is the key to shale gas development. To achieve this goal, high-volume injection of drag-reducing ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B43/26E21B43/267C09K8/64C09K8/72
Inventor 张劲周劲辉马新仿祝佳秋
Owner CHINA UNIV OF PETROLEUM (BEIJING)
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