Shale uniaxial compressive strength evaluation method based on rock debris micro-nano indentation experiment

Abstract

The invention discloses a shale uniaxial compressive strength evaluation method based on a rock debris micro-nano indentation experiment, and the method comprises the following steps: collecting rockdebris of a target shale reservoir, and treating the surface of a rock debris sample by adopting a three-ion beam cutting instrument, so that the surface becomes a flat and smooth high-quality section; carrying out a rock debris micron or nano indentation experiment on the treated rock debris sample to obtain a plurality of groups of indentation experiment load displacement curve graphs; and calculating the shale uniaxial compressive strength of the shale reservoir. According to the method, the shale debris micro-nano indentation experiment is carried out, indentation load depth curves under different scales are obtained, micromechanics parameters of shale are obtained through calculation, a relation model between uniaxial compressive strength and the micromechanics parameters is established, prediction of macromechanics parameters of shale is achieved, and the method is suitable for large-scale popularization and application. Therefore, shale mechanical parameters of the shale horizontal well are accurately obtained; basic parameter bases are provided for drilling, well completion and hydraulic fracturing of the shale gas horizontal well, and design and construction of drilling, well completion and hydraulic fracturing of the shale gas horizontal well can be effectively guided.

Description

technical field [0001] The invention relates to a method for evaluating the uniaxial compressive strength of shale based on micro-nano indentation experiments of cuttings, and belongs to the technical field of petroleum exploration and development. Background technique [0002] In recent years, my country's clean energy has continued to expand, and the construction of a clean and low-carbon energy system is accelerating. As the cleanest energy in traditional petrochemical energy, the demand for natural gas continues to increase. Shale gas has become the core growth point of my country's natural gas industry. In the process of shale gas exploration and development, shale uniaxial compressive strength and other mechanical properties are the key factors affecting the safe, efficient and economical exploitation of shale oil and gas. The whole process of exploration and development requires mastering the mechanical properties and distribution rules of shale: ①During the drilling ...

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Problems solved by technology

[0004] (1) Indoor experiments mainly use uniaxial and triaxial experimental methods; however, indoor experiments have strict requirements on sample size, and rock mechanical characteristics also have significant size effects. It is difficult to prepare standard rock samples, and the success rate of preparation is low; in addition, most of the indoor experiments cannot use downhole cores for comprehensive testing, so the experiments have serious randomness and variability; in addition, indoor experiments cannot obtain continuous uniaxial compression Intensity parameter profile (especially for horizontal wells in shale reservoirs), the obtained data has great limitations for engineering practicality

[0005] (2) Well logging method: Through laboratory calibration and interpretation of logging data, continuous rock mechanical parameter profiles can be obtained, but the accuracy of this method is still low, and because horizontal well logging is difficult and risky, domestic horizontal well logging There are still some difficulties in the well; for example, the traction force of the downhole crawler is limited, and the wellbore in the horizontal section is upturned, so it is difficult to overcome the friction resistance generated by the cable in the three-dimensional horizontal well, and usually only the logging of the horizontal section of about 200m to 400m can be completed; Rod transmission logging technology is relatively complicated, there are risks such as drill sticking and buried drilling, and it is time-consuming and costly, so it is rarely used; in addition, through-bit logging technology can take into account the advantages of cable and transmission logging, but it is still in the domestic In the research and development stage, the application has not yet been promoted

[0006] Therefore, it is not difficult to see that the petroleum industry has developed a series of rock mechanical property characterization methods based on uniform continuum mechanics, such as laboratory experiments and well logging methods; It is still difficult to obtain the uniaxial compressive strength parameters of rock horizontal wells, especially it is difficult to obtain the rock mechanical parameter profiles of horizontal wells that meet engineering requirements.

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