Carbon dioxide-anti-drag water compound fracturing method

Abstract

The invention provides a carbon dioxide-anti-drag water compound fracturing method which comprises the following steps of: injecting liquid carbon dioxide fracturing fluid into a stratum; after a period of time, stopping injecting the liquid carbon dioxide fracturing fluid, and then injecting anti-drag water fracturing fluid not added with a propping agent; and after a period of time, stopping injecting the anti-drag water fracturing fluid not added with the propping agent, then injecting anti-drag water compound fracturing fluid carrying the propping agent, and stopping after a period of time. According to the method, different system fracturing fluids are adopted in different injection phases, and special properties of different fracturing fluids are reasonably utilized, so that the effect of enlarging crack network scale, communicating stratum primary fractures, enhancing fracture efficiency, improving the seepage environment of the stratum and improving the reservoir yield; a carbon dioxide-anti-drag water compound fracturing process is applied to a low percolation oil and gas reservoir, so that the per-well yield can be improved, and the problem that traditional fracturing process for low percolation oil and gas reservoirs is poor in productivity improvement effect.

Description

technical field [0001] The invention relates to an oil well fracturing process in the downhole operation technology of oilfield exploration and development, specifically a carbon dioxide-drag reducing water composite fracturing method, which belongs to the technical field of oil and gas. Background technique [0002] With the development of the world's industrial level, the demand for oil and natural gas in various countries is gradually increasing. In order to increase production, the exploitation of low-permeability formations has become more and more important. It is true that the development and application of conventional fracturing technology has achieved good production stimulation effects in recent years, but at this stage people have to pay attention to some shortcomings of conventional fracturing technology. [0003] The disadvantages of conventional fracturing technology mainly include the following points: First, the main conventional fracturing requires a large ...

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Problems solved by technology

[0003] The shortcomings of conventional fracturing technology mainly include the following points: first, the main conventional fracturing requires a large amount of water, which will cause permanent damage to water-sensitive formations containing a large amount of clay minerals; Water lock effect occurs in the water body, which increases the difficulty of crude oil extraction; third, the fractures obtained by conventional fracturing are mostly single main fractures, without forming complex fracture networks, so the stimulation effect is poor; fourth, fracturing fluid residues will cause damage to the formation ; Fifth, the viscosity of the fracturing fluid used in conventional fracturing is relatively high, in order to achieve a better flowback rate, it will be more difficult to break the gel

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