Deep shale gas spiral type variable-parameter fracturing method

Abstract

The invention discloses a deep shale gas spiral type variable-parameter fracturing method. The deep shale gas spiral type variable-parameter fracturing method comprises the following steps: (1) evaluating a pre-fracturing formation; (2) determining the position of a section shower hole and carrying out perforating operation; (3) determining a fracturing fluid system and a proppant; (4) optimizingfracture parameters and fracturing construction parameters; (5) carrying out acid pretreatment; (6) fracturing and injecting low viscosity quick water in a first stage; (7) fracturing and injecting medium viscosity quick water in the first stage; (8) fracturing and injecting a glue solution in the first stage; (9) after the pumping in the first stage is finished, stopping pumping for 5-10 min; and(10) carrying out fracturing and pumping in a second stage; and (11) carrying out displacing operation. The deep shale gas spiral type variable-parameter fracturing method disclosed by the inventionhas the advantages that the fullness of a small and micro-scale fracture can be furthest enhanced, and the reducing rate of the effective fracture volume with the time is reduced. Therefore, the long-time fracturing stable yield is increased.

Description

technical field [0001] The invention relates to the technical field of shale gas reservoir reformation, and furthermore, relates to a deep shale gas spiral variable parameter fracturing method. Background technique [0002] At present, the number of deep shale gas fracturing wells is increasing, and there are more and more problems, such as high construction pressure, difficulty in adding sand, and even sand plugging. After fracturing, most single wells have low production and rapid decline . The reason is mainly due to the reference to conventional mid-shallow shale gas fracturing, and few specific targeted measures have been taken. [0003] In the past, the medium and shallow layer fracturing technology used a combination of fixed fracturing fluid viscosity and fixed proppant to carry out construction in the form of a section of sand and a section of fluid according to the designed pumping procedure, except that tension fractures could be generated during the fracturing p...

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Problems solved by technology

[0011] In order to solve the problems in the prior art, the present invention provides a spiral variable parameter fracturing method for deep shale gas, in which low-viscosity fracturing fluid and low-displacement pumping are repeated step by step through two fracturing construction stages. Construction combination, medium viscosity fracturing fluid and medium displacement pumping construction combination, high viscosity fracturing fluid and high displacement pumping construction combination, stop the pump for 5-10 minutes between the two fracturing stages While the fracture height extension should meet the design expectations, multi-scale fractures that match the viscosity of different fracturing fluids can be produced, and two small particle size low-density proppants of 140-230 mesh and 70-140 mesh should be used to design the sand in a spiral manner. Pumping construction in the form of liquid ratio completes multi-scale fracture filling, maximizes the filling degree of small and micro-scale fractures, reduces the decline rate of effective fracture volume over time, and thus improves long-term fracturing stability

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