High-frequency variable displacement volume fracturing method for atmospheric pressure shale gas reservoir

Abstract

The invention discloses a high-frequency variable displacement volume fracturing method for an atmospheric pressure shale gas reservoir. The method comprises the steps of (1) evaluation of shale key reservoir parameters, (2) optimization of crack parameters, (3) determination of geological engineering filling points and determination of cluster perforation positions, (4) optimization of fracturingconstruction parameters, (5) cluster perforation operation, (6) acid pretreatment operation, (7) injection construction of acid slick water for making main cracks, (8) neutral slick water high-displacement injection construction (9) 140-230 mesh or 70-140 mesh proppant middle-displacement injection construction (10) low-displacement injection construction of sealing liquid; (11) repeating of thesteps (8)-(10) until the total liquid amount and the proppant of a current section are used up; and (12) displacement operation. According to the invention, an acidic slick water system and a neutralslick water high-frequency variable displacement process are adopted. The production effect of the atmospheric pressure shale gas well after fracturing is improved, and the aim of economically and effectively developing the atmospheric pressure shale is better achieved.

Description

Technical field [0001] The invention relates to the field of petroleum exploitation, and more specifically, to a high-frequency variable displacement volume fracturing method for atmospheric shale gas reservoirs. Background technique [0002] The resources of atmospheric shale gas reserves are huge. The area of ​​Silurian shale with a buried depth of less than 3500m in the Sichuan Basin and its periphery is 82,000 square kilometers, of which atmospheric shale covers an area of ​​62,000 square kilometers and has a geological resource of 198,000. Billion square meters, accounting for 75.6%. However, restricted by its special geological characteristics, the stable daily output of atmospheric shale gas horizontal wells after hydraulic fracturing measures is generally less than 30,000 m3, the output is relatively low and the rate of decline is relatively fast. Therefore, the current large-scale multi-stage fracturing technology has poor adaptability to atmospheric shale, and it is di...

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Problems solved by technology

However, due to its special geological characteristics, the stable daily production of normal pressure shale gas horizontal wells after hydraulic fracturing is generally less than 30,000 cubic meters, and the production is relatively low and the decline rate is fast.

[0005] The above-mentioned mismatch of geological characteristics and fracturing techniques has resulted in a reduction in the complexity of fracturing fractures in normal-pressure shale gas wells, as well as low production and rapid production decline after fracturing. Therefore, it is necessary to study and propose a new method for normal-pressure shale gas wells The new technology of horizontal well volume fracturing based on gas reservoir characteristics can solve the above limitations and truly realize the economical and effective development of normal pressure shale gas

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