Fracturing method for deep shale gas through V-shaped pressure curve

Abstract

The invention discloses a fracturing method for deep shale gas through a V-shaped pressure curve. The fracturing method comprises the steps of (1) key reservoir parameter evaluation, (2) optimizationof fracture parameters and fracturing construction parameters, (3) perforation position determination and perforation operation, (4) acid pretreatment, (5) variable-displacement and low-viscosity slick water joint forming construction, (6) powder pottery construction for adding different sand liquid ratios into low-viscosity slick water, (7) medium-particle-size proppant construction for adding different sand liquid ratios into medium-viscosity slick water, (8) high-viscosity gel and large-particle-size carrying proppant construction, and (9) displacing operation. According to the fracturing method, complexity of fracturing fractures of the deep shale gas is improved, the filling ratios of systems with different scales of fractures such as near wells, far wells, main fractures and micro-fractures are increased, the effective stimulation volume of the deep shale gas is increased, and the yield increasing and stabilizing effects after pressure are improved.

Description

technical field [0001] The invention relates to the field of oil and gas exploitation, in particular to a fracturing method for a "V"-shaped pressure curve of deep shale gas. Background technique [0002] With the deepening of shale gas exploration and development, shale gas with a vertical depth of more than 3500 m has basically been commercially developed, but the importance of deep shale gas with a vertical depth of more than 3500 m has become increasingly prominent. Only in the Sichuan Basin, deep shale gas The amount of natural gas resources is more than one trillion cubic meters. At present, the production of deep shale is low after gas pressure, and the decline is fast, so it is difficult to obtain economic development value. From a technical point of view, the difficulties of deep shale gas fracturing are mainly as follows: [0003] 1) With the increase of burial depth, the three-dimensional stress increases. Among them, the increase of the two-dimensional horizont...

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Problems solved by technology

[0003] 1) With the increase of burial depth, the three-dimensional stress increases. Among them, the increase of the two-dimensional horizontal stress difference increases the difficulty of fracture steering and reduces the complexity of fractures; the increase of vertical stress makes horizontal bedding fractures or It is more difficult to open and extend the grain seam, which reduces the lateral spread of the main fracture;

[0004] 2) The increase of temperature and pressure enhances the plasticity of the rock. Therefore, the crack initiation and extension pressure increase, and the embedding depth of the proppant also increases, which reduces the fracture conductivity;

[0005] 3) As the effective closure stress increases, the proppant fragmentation rate increases, which further reduces the conductivity of the fracture;

[0007] In view of the above limitations, deep shale gas fracturing technology has been developed into a multi-stage variable parameter fracturing technology, including variable viscosity, variable displacement, variable proppant particle size, etc., but the lack of implementation control technology makes it difficult to operate on site. Completely follow the design, so it is difficult to achieve the designed stimulation effect, which is not conducive to improving the complexity of deep shale gas fractures and maximizing the effective stimulation volume

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