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

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 ...

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.

Images