Shale gas fracturing and sand adding method

Abstract

The invention discloses a shale gas fracturing and sand adding method. The shale gas fracturing and sand adding method comprises the steps of (1) optimizing crack parameters and fracturing construction parameters; (2) optimizing cluster perforation parameters; (3) acid pretreatment; (4) variable-viscosity and variable-displacement prepad fluid fracture forming; (5) small-particle-size proppant slug type sand adding; (6) adding sand into a 40-70 mesh proppant low-sand-liquid-ratio long-section plug at a first section for fracturing; (7) mixing powder ceramic with a 40-70 mesh proppant in a following manner, adding sand and fracturing; (8) fracturing and filling the proppant with high sand-liquid ratio and large particle size; and (9) conducting large-flow-rate displacement under wellhead pressure limiting. According to the shale gas fracturing and sand adding method, the uniform transformation degree and the sand adding amount of multi-cluster perforation in the section can be increased, uniform transformation of multi-cluster cracks in the section and effective increase of the dosage scale of the proppant are achieved, so that the filling degree of the proppant in small-crack wide-scale cracks is improved, and the flow conductivity of a crack system is improved. And the method is particularly suitable for sand fracturing transformation of deep and complex-structure shale and stratified-fracture-development shale gas reservoirs.

Description

Technical field[0001]The present invention relates to the technical field of shale gas reservoir reconstruction, and more specifically, to a method for adding sand by shale gas pressure fracturing.Background technique[0002]With the deepening of domestic shale gas exploration and development, the geological conditions of shale gas are becoming more and more complicated, and at the same time, it brings more problems to hydraulic sanding and fracturing technology. Generally, shale gas fracturing will use a certain amount of glue or slippery water as the pre-fracturing fluid to make fractures before the formal sanding. After the fractures reach the designed size, the fracturing fluid will continue to carry different particles. The proppant with a smaller diameter enters the fracture, so that the proppant fills and supports the fracture, thereby forming an effective flow channel for shale gas production.[0003]The sand fracturing construction with proppant carried by the fracturing fluid ...

AI Technical Summary

Problems solved by technology

[0017] In order to solve the problems in the prior art such as the narrow width of fractures formed by fracturing of deep shale and complex structure shale, the difficulty of adding sand, the high risk of sand plugging in construction with high sand liquid ratio, and the difficulty in guaranteeing the scale of proppant, the present invention provides a The shale gas fracturing sanding method is a single sanding stage small particle size proppant followed by the main proppant and a long slug sanding method with a low sand liquid ratio. The combination of technologies such as continuous sand addition to slugs with a long liquid ratio, follow-up injection of mixed powder pottery in the main proppant stage, and staged increase in displacement of spacer fluid can improve the uniformity of reconstruction and sand addition in multi-cluster perforations in the section, and realize The uniform reconstruction of multi-cluster fractures and the effective increase of proppant dosage scale can improve the filling degree of proppant in fractures with small fracture width and improve the conductivity of fracture system

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