Fracturing method for shale reservoir microfracture self-supporting

A technology for shale reservoirs and micro-fractures, which is used in earth-moving drilling, production of fluids, wellbore/well components, etc., can solve the problems of unsolved implementation process or operation method, etc., and achieve high fracture conductivity and stability. Good results

Pending Publication Date: 2021-01-12
CHINA PETROLEUM & CHEM CORP +1
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  • Application Information

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Problems solved by technology

The literature only studies the test method of self-supporting fracture conductivity theoretically, and analyzes the main controlling factors affecting self-

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  • Fracturing method for shale reservoir microfracture self-supporting
  • Fracturing method for shale reservoir microfracture self-supporting

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Embodiment 1

[0073] Well J is a marine shale gas horizontal well. The target layer of this well is the Lower Silurian Longmaxi Formation-Upper Ordovician Wufeng Formation, and the middle vertical depth of the target layer is 3810m. The average quartz content of the well target layer is 51.8%, the average carbonate content is 6.8%, the shale is 23.1%, the average Poisson’s ratio is 0.21, the Young’s modulus is 46.6GPa, the brittleness index is 67%, and the two-way horizontal stress difference coefficient is 0.165 , compressibility index 0.55. The imaging logging shows that the horizontal bedding of the target layer is developed, and there are high conductivity fractures and high resistance fractures in some intervals. From the perspective of engineering geological parameters, the target layer of this well has high brittleness index, small difference in horizontal stress, and natural fractures in some intervals, which are very conducive to the development of fracture network fracturing. How...

Embodiment 2

[0091] Well H is a marine deep shale gas horizontal well. The target layer of this well is the Lower Silurian Longmaxi Formation-Upper Ordovician Wufeng Formation, and the vertical depth in the middle of the target layer is 4095m. The average content of quartz in the target layer of this well is 41.1%, the average carbonate content is 14.4%, the shale is 26.4%, the closing pressure is 97MPa, the average Poisson’s ratio is 0.22, the Young’s modulus is 43GPa, the brittleness index is 65%, and the two-way horizontal stress difference The coefficient is 0.21, the two-way horizontal stress difference is 19-22.2MPa, and the compressibility index is 0.55. Imaging logging shows that the high-angle fractures in the target layer are generally well developed, mostly half-filled or filled by calcite and pyrite, and horizontal bedding fractures are well developed. From the perspective of engineering geological parameters, the target layer of this well has a high brittleness index and natur...

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Abstract

The invention discloses a fracturing method for shale reservoir microfracture self-supporting. The method comprises the steps that (1) reservoir characteristic parameter evaluation before fracturing,fracture parameter and perforation position optimization and fracturing construction parameter optimization are carried out; (2) acid pretreatment is carried out; (3) a high-viscosity glue solution ispreposed to form cracks; (4) medium-viscosity slippery water extends to form branch seams and small micro-cracks; (5) supercritical carbon dioxide is injected to further extend the small micro-cracks; (6) non-uniform etching treatment is performed on the wall surfaces of the cracks by using medium clay acid; (7) construction of low-clay acid in the small-micro-scale cracks is carried out; and (8)seam filling is carried out by medium-viscosity slippery water carrying a propping agent. According to the method, self-supporting complex fracture systems which have different fracture width scalesand are communicated with each other can be formed. By implementing the process, the flow conductivity and the effective crack volume of the crack systems of high-brittleness shale, deep-layer shale and complex shale layers difficult to add sand are improved.

Description

technical field [0001] The invention relates to the technical field of shale gas reservoir transformation, in particular to a fracturing method for self-supporting micro-fractures of shale reservoirs. Background technique [0002] Large-scale staged fracturing of shale gas horizontal wells is one of the key technologies to realize the commercial development of shale gas. Generally, a large amount of proppant needs to be added during the hydraulic fracturing process to fill and support the fractures, so that the fractures can maintain a certain flow conductivity and provide effective flow channels for subsequent gas testing and production. Due to the brittleness of shale rock itself, and the distribution and development of weak surface structures such as natural fractures and beddings in reservoirs are different, hydraulic fracturing will not only produce main fractures with relatively large fracture widths at the millimeter level, but also Micron-scale small micro-scale fra...

Claims

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Application Information

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IPC IPC(8): E21B43/267E21B43/27
CPCE21B43/267E21B43/26
Inventor 蒋廷学王海涛仲冠宇左罗卞晓冰卫然肖博苏瑗李奎为
Owner CHINA PETROLEUM & CHEM CORP
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