Deep shale gas stepless variable-parameter slope type injection fracturing method

Abstract

The invention discloses a deep shale gas stepless variable-parameter slope type injection fracturing method. The method includes the steps of (1) evaluation of key shale parameters; (2) determinationof a perforation cluster position; (3) optimization of crack parameters; (4) optimization of fracturing construction parameters; (5) preparation of slick water variable in viscosity; (6) preparation of glue variable in viscosity; (7) combined construction of perforation and running of bridge plugs; (8) acid pretreatment operation; (9) glue crack formation or crack height control construction of the low-viscosity slick water carrying sand; (10) main crack formation construction of the low-viscosity slick water; (11) variable-parameter injection and sand addition construction; (12) displacing operation. The method is reasonable in design and high in feasibility, and the filling degree of cracks at all levels is maximized according to four parameters including the fracturing fluid viscosity,the injection discharge mount, the construction sand-liquid ratio and the segmental sand addition mode or the continuous sand addition mode, so that high output in the early period is guaranteed to acertain extent, and meanwhile a stable production effect after fracturing can be stabilized.

Description

technical field [0001] The invention relates to the technical field of petroleum drilling, and more specifically, relates to a slope-type injection fracturing method for deep shale gas with stepless variable parameters. Background technique [0002] At present, the number of deep shale gas fracturing wells is increasing, but as the depth increases, the three-dimensional stress increases, and the two-dimensional horizontal stress difference also increases, making it more difficult to form complex fractures. The increase of the minimum horizontal principal stress reduces the net pressure of the fracture, and while the complexity of the fracture decreases, the conductivity in fractures of different scales decreases. The increase of overlying stress makes it more difficult to open and extend horizontal bedding fractures and texture fractures; the increase of depth leads to the increase of wellbore friction, which in turn reduces the injection displacement and reduces the geometr...

AI Technical Summary

Problems solved by technology

[0003] Therefore, the effect of deep shale gas fracturing is poor, and the production declines rapidly. It is urgent to study and propose a new volume fracturing technology suitable for deep formations to solve the above technical limitations.