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A method for improving the connectivity of microfractures in hot dry rock fracturing

A technology of micro-cracks and hot dry rocks, applied in the field of hot dry rock fracturing, can solve the problems that cannot be used to form branch fractures interconnected, and achieve the effects of increasing connectivity, avoiding fluid short circuit, and increasing flow and temperature

Active Publication Date: 2022-07-05
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This patent is aimed at a method for the construction of artificial heat storage in hot dry rock. The method is to use supercritical carbon dioxide to form cracks, and then generate secondary fractures in large-scale construction. It cannot be used to form branch cracks and dissolution cracks and make them interact with each other. Connected, no methods to improve fracture connectivity are involved

Method used

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  • A method for improving the connectivity of microfractures in hot dry rock fracturing
  • A method for improving the connectivity of microfractures in hot dry rock fracturing
  • A method for improving the connectivity of microfractures in hot dry rock fracturing

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Experimental program
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Effect test

Embodiment 1

[0042] (1) Liquid preparation. According to the specific fracturing design requirements of a dry-hot rock well, prepare 1.1 times the design dosage of 0°C clean water and acid slick water with a pH value of 3 and a viscosity of 5mPa.s.

[0043] (2) Conventional fracturing construction. With a displacement of 2.0m3 / min, according to the designed liquid consumption of 200m 3 Pump water at 0°C to form micro-fractures in hot dry rock.

[0044] (3) Multi-stage temporary plugging fracturing. After the formation of micro-cracks along the direction of the maximum principal stress, continue with 2.0m 3 The displacement per minute carries 100kg of temporary plugging agent (powder pottery, particle size range 140-200 mesh) in the fracture to expand the fracture forward until the pumping fluid volume reaches the fracturing design fluid volume (fracturing design fluid volume level is 200m 3 ), add 150kg of temporary plugging agent in the joint, and continue to press 2.0m 3 When the wa...

Embodiment 2

[0050] (1) Liquid preparation. According to the specific fracturing design requirements of a dry-hot rock well, 1.1 times the design dosage of 4°C clean water and 9mPa.s acid slick water with a pH value of 5 and a viscosity were prepared.

[0051] (2) Conventional fracturing construction. With a displacement of 1.5m3 / min, according to the designed liquid consumption of 150m 3 Pump water at 4°C to form micro-fractures in hot dry rock.

[0052] (3) Multi-stage temporary plugging fracturing. After the formation of micro-cracks along the direction of the maximum principal stress, continue with 1.5m 3 The displacement per minute carries 150kg of temporary plugging agent in the fracture (powder ceramic, particle size range of 140-200 mesh) to expand the fracture forward until the pump injection volume reaches the fracturing design fluid volume (fracturing design fluid volume level is 300m 3 ) of 40%, add 200kg of temporary blocking agent in the joint, and continue to 3 When the...

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Abstract

The invention discloses a method for improving the connectivity of micro-cracks in dry-hot rock fracturing. Including: step (1) liquid preparation: preparing clean water at 0-4°C and acid slick water with pH value of 3-5; step (2) fracturing with clean water at 0-4°C to form micro-cracks along the direction of maximum principal stress step (3) multi-stage temporary plugging fracturing to form lateral micro-cracks; step (4) acid slick water to form dissolution fractures. The invention adopts high displacement to carry out multi-stage temporary plugging fracturing, greatly increases the net pressure in the fractures, diverts and extends the fractures at different positions, and then injects acidic slick water to dissolve the fillings in the hot dry rock, so that the micro-fractures are formed. , Turning micro-cracks and dissolution fractures are connected to form a micro-crack network system, reducing the fluid resistance to 0.1MPa.kg ‑1 .s ‑1 In the following, the short circuit of the fluid in the later water injection heat exchange process is avoided, the fluid flow rate and temperature of the heat exchange are increased, and the support for the efficient utilization of geothermal resources is provided.

Description

technical field [0001] The invention relates to the technical field of dry-hot rock fracturing, in particular to a method for improving the connectivity of micro-cracks in dry-hot rock fracturing. Background technique [0002] Hot dry rock is a kind of high temperature rock mass buried in the stratum 3-10km deep, mainly granite, there is no fluid or only a small amount of underground fluid inside the rock, and the porosity and permeability are extremely poor, and the temperature is above 150 ℃. Large-scale occurrences occur in southern Tibet, western Yunnan, and southeastern coastal areas. The fracturing is carried out in the hot dry rock reservoir to form a fracturing fracture network system, and water is injected into the fracture network system for heat exchange. It is one of the most effective ways to utilize hot dry rock resources at present. At present, the fracturing of hot dry rock mainly adopts the large-scale fracturing technology of clear water, and the construc...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): E21B43/26F24T10/20
CPCE21B43/26F24T10/20Y02E10/10
Inventor 陈作曾义金李奎为李洪春周健刘世华吴春方卫然刘斌彦
Owner CHINA PETROLEUM & CHEM CORP