Critical sand plug fracturing method for improving crack complexity

Abstract

The invention discloses a critical sand plug fracturing method for improving crack complexity. The method includes the following steps: (1) formation evaluation before fracturing; (2) preferable selection of viscosity of pre-crack generation fracturing fluid; (3) application of different viscosity fracturing fluid to generate cracks of different sizes at different stages; (4) preferable selectionof dosage proportion and particle size of a proppant matching the different crack sizes; (5) design of a bench type slug sanding mode; (6) implementation of a critical sand plug fracturing process; and (7) other construction steps and a flowback and production process. The method realizes the effective promotion of net pressure and an induced stress field in the whole process of one-time sand fracturing, thereby reducing a horizontal stress difference of two directions of a formation at different positions of a main crack to make the opening of natural cracks or micro cracks filled with calcium easier. The main crack turns and then communicates and intersects with the natural cracks or the micro cracks, thereby maximizing the complexity of the whole crack system and further improving the crack reconstruction volume and single well production.

Description

technical field [0001] The invention relates to the technical field of shale gas development, in particular to a critical sand plugging fracturing method for increasing the complexity of fractures. Background technique [0002] At present, horizontal well volume fracturing technology has been widely applied in shale gas exploration and development, and has successfully achieved commercial breakthroughs in Sinopec's Jiaoshiba area and PetroChina's Changning-Weiyuan area. The main technological measures adopted are high displacement, large liquid volume, low viscosity and low sand-to-liquid ratio, and supporting the use of fracturing fluid with two viscosities of slick water and glue, and 70-140 mesh, 40-70 mesh and 30 mesh -50 mesh proppant, and multi-stage proppant slug technology, etc., to achieve the purpose of volume fracturing reconstruction. [0003] The document "Research and Test on New Technology of Multi-fracture Fracturing" ("Petroleum Drilling and Production Tech...

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Problems solved by technology

[0012] In order to solve the unreasonable selection of liquid viscosity and proppant particle size as well as the unreasonable design of construction parameters such as construction displacement and sand-liquid ratio in the prior art, the complexity of the fractures caused is not high, the volume of reservoir stimulation is limited, and the fracturing Unsatisfactory effects, etc., the present invention provides a critical sand plugging fracturing method that increases the complexity of fractures

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