Evaluation method for brittleness of shale

An evaluation method and shale technology, applied in the field of oil drilling, can solve the problems of high cost, inability to evaluate shale brittleness, complicated rock sample preparation process, etc., and achieve the effect of low cost and simple sampling process

Inactive Publication Date: 2019-08-30
SHAANXI TECHN INST OF DEFENSE IND
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Problems solved by technology

Existing shale brittleness evaluation methods can be mainly divided into six categories based on mineral composition, elastic mechanical parameters, rock strength, penetration test, rock fragmentation degree, and indoor stress-strain. These evaluation methods mainly rely on post-drilling logging interpretation. And the mechani

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  • Evaluation method for brittleness of shale
  • Evaluation method for brittleness of shale
  • Evaluation method for brittleness of shale

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Embodiment

[0020] The shale brittleness evaluation method of this embodiment includes the following steps: (1) Select a group of drilling cuttings from different shale reservoir sections and the corresponding standard shale samples as the test and research objects, and carry out microscopic analysis on the shale cuttings. Nanoindentation, X-ray diffraction, and density tests are used to test the compressive strength of the corresponding standard shale samples (under the same confining pressure); (2) the elastic modulus, The content of mineral components and the density of shale cuttings were substituted into the brittleness evaluation model The relative value of brittleness of the same group of shale cuttings is calculated, as shown in Table 1; (3) The relative value of brittleness calculated from shale cuttings is compared with that of the corresponding standard shale sample (under the same confining pressure) after the compressive strength test degree of fragmentation ( figure 2 )Co...

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Abstract

An evaluation method for brittleness of shale includes the following steps: (1) obtaining shale cuttings returned from a target shale gas well bottom, and separately performing microscopic nanoindentation, X-ray diffraction and density tests; (2) based on obtained data of the microscopic nanoindentation, X-ray diffraction and density tests, separately calculating an elastic modulus, a component content and rock debris sample density constituted by various types of mineral substances of each of the shale cuttings; and (3) substituting the elastic modulus, mineral component content and a shale cuttings density value constituted by the various types of mineral substances of each of the shale cuttings into a brittleness evaluation model formula, wherein Wi represents a content of an i mineralcomponent in the shale; Ei represents the elastic modulus of i mineral composition in the shale, GPa; [rho] represents shale density, g/cm3, and a B value obtained by the model reflects a brittlenesscharacteristic of a shale reservoir where the shale is located. The method can perform real-time evaluation on the brittleness of the shale simply, quickly and at low cost.

Description

technical field [0001] The invention relates to the technical field of oil drilling, in particular to a shale brittleness evaluation method while drilling. Background technique [0002] During the shale gas drilling process, the real-time and correct evaluation of shale brittleness is helpful for the timely prevention and control of wellbore stability, the optimization of fracturing intervals and the optimization of fracturing effects, and it also has certain implications for the selection of drilling equipment and cement slurry density influences. Existing shale brittleness evaluation methods can be mainly divided into six categories based on mineral composition, elastic mechanical parameters, rock strength, penetration test, rock fragmentation degree, and indoor stress-strain. These evaluation methods mainly rely on post-drilling logging interpretation. And the mechanical experiment of rock sample preparation, logging interpretation cannot be used for real-time shale brit...

Claims

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Application Information

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IPC IPC(8): G01N3/08G01N23/20G01N23/2005G01N23/207G01N9/02G01N1/32
CPCG01N1/32G01N3/08G01N9/02G01N23/20G01N23/2005G01N23/207G01N2009/026G01N2203/0019G01N2203/0075G01N2203/0078
Inventor 张涛
Owner SHAANXI TECHN INST OF DEFENSE IND
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