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Influence of formation in-situ stress on mechanical heterogeneity of shale through grid nanoindentation
- Source :
- Petroleum Science. 19:211-219
- Publication Year :
- 2022
- Publisher :
- Elsevier BV, 2022.
-
Abstract
- Mechanical heterogeneity is a major characteristic of the organic-rich shale. The relation between mechanical heterogeneity and formation in-situ stress has been seldomly addressed but important to understand hydraulic fracture propagation, wellbore stability, and hydrocarbon flow. In this paper, the grid nanoindentation technique was used to characterize the heterogeneity of the mechanical properties of Longmaxi organic-rich shales from various burial depths and in-situ stress. The measured elastic modulus and hardness of each sample are deconvolved into three phases including soft phase, medium stiff phase and stiff phase according to mineral category. As the burial depth and corresponding in-situ stress increase, the overall elastic modulus and hardness of the sample enhance. Simultaneously, the percentage of soft minerals decreases, and the probability distribution tends to concentrate through 95% confidence interval evaluation which demonstrates weakened heterogeneity. Furthermore, SEM images provide evidence that extended cracking, initiated cracking, crushing and ductile deforming always occur around indentation imprints. This confirms that even under deep buried depth and high in-situ stress, brittle fracture and ductile deformation can exist synchronously. This paper demonstrates the influence of in-situ stress on the heterogeneity of shale micromechanics.
- Subjects :
- Materials science
Energy Engineering and Power Technology
Micromechanics
Geology
Nanoindentation
Geotechnical Engineering and Engineering Geology
Stress (mechanics)
Cracking
Geophysics
Fuel Technology
Geochemistry and Petrology
Indentation
Economic Geology
Deformation (engineering)
Composite material
Oil shale
Elastic modulus
Subjects
Details
- ISSN :
- 19958226
- Volume :
- 19
- Database :
- OpenAIRE
- Journal :
- Petroleum Science
- Accession number :
- edsair.doi...........843e2e1b964ed350d3b440b1c7c38cdc