Reservoir brittleness evaluation method based on microscopic features of rock fragments and drilling parameters

Abstract

The invention discloses a reservoir brittleness evaluation method based on microscopic features of rock fragments and drilling parameters. Roughness testing is carried out rock fragments to obtain a shale brittleness evaluation parameter B1; backscattered electron imaging (BSE), energy spectrum analysis (EDX) and nanoindentation experiments are performed to obtain microscopic rock mechanics parameters of rock fragments and carry out inversion on the parameters, shale micro-constitutive is established, upgrading is carried out to obtain macroscopic constitutive and corresponding macroscopic rock mechanics parameters and brittleness indexes B2 and B3; with finite-element simulation software, the shale macroscopic constitutive and corresponding rock mechanics parameters are applied to a drillcolumn-bit-rock-rock finite element model and on-site drilling information is inputted to obtain drilling parameters; according to the obtained drilling parameters, a brittleness-drilling parameter correlation model is established to obtain a brittleness index B4; and with the B1, B2, B3 and B4, a comprehensive brittleness evaluation model based on drilling parameters and rock fragment microscopic characteristics is established and a comprehensive brittleness evaluation parameter B is calculated. The method is simple and effective and the test cost is low.

Description

technical field [0001] The invention relates to the technical field of shale gas development, in particular to a reservoir brittleness evaluation method based on cuttings microscopic characteristics and drilling parameters. Background technique [0002] Since the shale gas revolution in the United States, unconventional natural gas has begun to pour into the global natural gas market in large quantities, and the historical pattern of natural gas market separation will be gradually broken. The competition in the natural gas market is becoming increasingly fierce, market liquidity is enhanced, and the bargaining power of natural gas importing countries is enhanced. The international natural gas market is moving towards integration. Development and utilization have also been further pushed to new heights. According to an authoritative statement issued by the Ministry of Land and Resources in 2017, China has become a major producer of shale gas alongside the United States and C...

AI Technical Summary

Problems solved by technology

[0003] In conventional brittleness evaluation, it is often necessary to use well logging methods to obtain downhole rock mechanics parameters or to adopt macroscopic rock mechanics experiments. However, the existing methods for measuring rock macroscopic rock mechanics experiments mainly include technical means such as uniaxial / triaxial compression tests and acoustic wave experiments. Obtain the full stress-strain curve of the macroscopic rock core sample (CN201710137576-a method for obtaining rock brittleness index and rock brittleness evaluation method, CN201610655794-a kind of rock brittleness test method), but the above commonly used petrological parameter measurement method is in Shale gas drilling has limitations such as difficult coring, high testing costs, and poor core representation. At the same time, logging can obtain brittleness evaluation parameters of downhole reservoirs (CN201610900051-method and system for obtaining rock brittleness index, CN201410575775-一 A logging method and device for rock brittleness - application disclosure), but the test period of this technical means is long and lacks immediacy. Some scholars have proposed a method for evaluating the brittleness of shale reservoirs by using the microscopic characteristics of cuttings (CN201510799922-a The fracturing evaluation method of shale based on the microscopic characteristics of cuttings), but the microscopic constitutive of shale has not been upgraded to macroscopic constitutive, and the mechanical properties of macroscopic shale rock cannot be completely and accurately characterized. At the same time, the above conventional None of the methods established a brittleness evaluation method based on drilling parameters.

Images