Composite mixed-phase fracturing method of chemical agent and carbon dioxide for low-permeability reservoir

Abstract

The invention relates to composite mixed-phase fracturing methods of chemical agents and carbon dioxide for low-permeability reservoirs, and provides a composite mixed-phase fracturing method of a chemical agent and carbon dioxide for low-permeability reservoir reconstruction. The composite mixed-phase fracturing method adopts a matching chemical additive and the carbon dioxide for mixed pump injection to achieve reconstruction of a stratum. The method comprises the following steps of unblocking by using non-flowback acid and the chemical agent, fracturing by using slickwater and the chemical agent, and turning fracturing and phase mixing by using the carbon dioxide and the chemical agent which are orderly performed. The method can effectively solve the problems of high reservoir stratum sensitivity, low reservoir stratum permeability, insufficient energy, fast decline of oil well yield, poor effect of conventional measures, short period and the like in development of low-permeability reservoirs, and realizes dredging of a seepage channel of the low-permeability reservoir, improvement of fluidity of crude oil and construction of a complex net-shaped three-dimensional fracture system; and the reservoir is effectively protected, and the productivity of a single well and the production degree of the low-permeability reservoir are greatly improved.

Description

technical field [0001] The invention belongs to the field of oil and gas development, and in particular relates to a chemical agent and carbon dioxide composite miscible fracturing method for production stimulation of low-permeability oil reservoirs. Background technique [0002] Low permeability oil and gas fields are of great significance in oil and gas development in my country. The distribution of low-permeability oil and gas resources in my country has the characteristics of rich oil and gas, various types of oil and gas reservoirs, and wide distribution areas. Among the proven reserves, the proportion of low-permeability oil and gas reserves accounts for more than 2 / 3 of the national reserves, and the development potential is huge. . [0003] The oil and gas resources discovered in my country in the past 10 years have an annual increase of 400 million to 500 million tons of reserves, but about 70% are low-permeability and ultra-low-permeability oil and gas reservoirs. ...

AI Technical Summary

Problems solved by technology

The main characteristics of low-permeability oil and gas reservoirs are extremely low permeability, strong reservoir sensitivity, easy to be polluted, and difficult to recover after pollution. In addition, this type of oil and gas reservoir has fast elastic energy depletion, difficult water injection, and oil well production declines rapidly, and soon will enter the inefficient development stage

[0004] In the prior art, conventional fracturing stimulation operations are used for low-permeability oil and gas reservoirs. Due to the poor physical properties of low-permeability oil and gas reservoirs, high viscosity of crude oil, water sensitivity and salt sensitivity are prone to occur, and the formation is easy to be polluted. In terms of process implementation also have great limitations

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