Composite acid fracturing method for improving flow conductivity of ultra-deep carbonate reservoir and application

Abstract

The invention discloses a composite acid fracturing method for improving flow conductivity of an ultra-deep carbonate reservoir and application. The method comprises the steps that firstly, low-viscosity low-friction neutral slickwater is injected to form cracks, then low-viscosity low-friction strong-acid slickwater is injected to etch the formed cracks, the displacement is gradually increased, the neutral slickwater and the acid slickwater are injected in a circulating mode, after the corrosion range and the crack width of acid liquor are gradually enlarged, self-suspension propping agents with different particle sizes are added from small to large to support formed main crack and branch crack micro-crack systems, and finally displacement operation is conducted. According to the method, the construction displacement and the net pressure in the cracks can be effectively increased, the transformation range and the corrosion width of the acid liquor are enlarged, adding of the self-suspension propping agents is facilitated, the flow conductivity of the multiple types of acid etching cracks under the ultra-deep condition is improved, and the production stability and the long-term performance are kept.

Description

technical field [0001] The invention relates to the technical field of petroleum exploitation, and more particularly relates to a compound acid fracturing method and application for improving the diversion capacity of an ultra-deep carbonate rock reservoir. Background technique [0002] At present, the proportion of ultra-deep carbonate rocks discovered and put into development is gradually increasing. For example, in the Shunbei Oilfield in the Tarim Basin, the vertical depth generally exceeds 7300m, and some well layers even have a vertical depth close to 9000m. With the increase of vertical depth, the following challenges are brought to the acid fracturing stimulation: 1) The friction along the wellbore increases, and the injection displacement decreases, which affects the fracture creation ability; 2) The closure stress and Young's modulus increase significantly , leading to a reduction in the width of the fracture, increasing the resistance of the acid or fracturing flu...

AI Technical Summary

Problems solved by technology

[0008] Although some improvements have been made in the above patents and documents, the problems of high construction cost and rapid decline of diversion capacity under ultra-high closure stress have not been fundamentally changed.