A volumetric fracturing method of solid acid encapsulated in deep shale gas microcapsules

Abstract

The invention discloses a deep shale gas microcapsule-coated solid acid volume fracturing method. The method includes the steps of (1) evaluation of key parameters of a target layer and upper and lower shale; (2) determination of a segment cluster position; (3) optimization of crack parameters and fracturing construction parameters; (4) preparation of microcapsule-coated solid acid; (5) preparation of slick water and glue which are variable in viscosity, wherein the viscosity range of the slick water is 1-12 mPa.s, and the viscosity of the glue is 30-70 mPa.s; (6) perforation operation; (7) acid pretreatment operation; (8) injection of the slick water variable in viscosity and discharge amount for construction, wherein the slick water is injected in three stages, and the viscosity of the slick water is gradually increased; (9) injection of 140-230 mesh ceramic powder and 140-230 mesh microcapsule-coated solid acid particles; (10) construction of the glue variable in viscosity and discharge amount; (11) injection of 70-140 mesh ceramic powder and 70-140 mesh microcapsule-coated solid acid particles; (12) displacing operation. A construction process of the method is simple, the operation is simple, and the method has a broad application prospect in shale gas fracturing.

Description

technical field [0001] The invention relates to the technical field of petroleum drilling, and more specifically relates to a volume fracturing method of solid acid wrapped in microcapsules of deep shale gas. Background technique [0002] At present, the exploration and development of shale gas is gradually moving towards deep layers, and there are huge reserves of shale gas in deep structures such as the southern Fuling structure, Changning-Weiyuan, Nanchuan and Dingshan in the Sichuan Basin. However, due to the increase in buried depth, fracturing has brought great challenges. Specifically, the wellbore friction is high, the wellhead pressure and the corresponding displacement decrease, resulting in narrow fracture width, low construction sand-liquid ratio and low fracture conductivity; the three-dimensional in-situ stress increases correspondingly, especially the two-dimensional horizontal stress difference increases, the complexity of cracks decreases. With the increas...

AI Technical Summary

Problems solved by technology

[0003] In view of the above problems, most of the current deep shale gas fracturing technology models and main process parameters still adopt the conventional medium and shallow fracturing method. At present, it is difficult to add sand to some wells, and the sand-liquid ratio and sand addition volume cannot reach Design requirements