Hazra, Bodhisatwa and Singh , Ashok K Singh and Sethi, Chinmay and Wood , David A (2023) Experimental protocols to determine reliable organic geochemistry and geomechanical screening criteria for shales. Journal of Earth System Science .

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Abstract

Unconventional shale petroleum systems, owing to their petroleum generation and storage properties have gained tremendous exploitation and research interest in recent years. Moreover, their emergence as potential atmospheric carbon dioxide sinks has further warranted a detailed examination of their multiple properties. Laboratory geochemical screening and geomechanical investigations provide valuable information for classifying these reservoirs. Although some guidelines exist for conducting such analyses, the analytical methods and sampling techniques applied do influence the quality of the derived measurements. For laboratory geochemical screening using the Rock-Eval technique, various factors including sample grain size, type of kerogen, sample quantity, and nature of S2 and S4 curves, all substantially influence the quality of the data generated. In this work, we summarize the different factors that influence the data generated from Rock-Eval analysis and recommend a method that involves optimization of sample weight and sizes for the generation of reliable geochemical data. A new emerging technology in the field of organic petrography for the simultaneous characterization of organic and inorganic phases in shales has also been discussed. Once source-rock potential of the shale formation is ascertained, the next step is a selection of suitable target shale reservoir zones, and designing successful hydraulic fracturing programs for the exploitation of the reservoir. For this purpose, detailed knowledge of geomechanical properties is essential. However, the quantity of intact shale-core samples recovered from coring operations is typically insufficient for reliably analyzing geomechanical properties by applying the established standards. A comparison is made between the uniaxial compressive strength and Young's modulus measurements on shale specimens of different length-to-diameter ratios. It reveals that specimens smaller than the recommended standard exhibit unacceptable variations in the values of strength and elastic parameters they generate. To overcome this, it is justified to use alternative techniques suited to the small sample sizes typically recovered in borehole shale cores. For instance, a punching tool and nanoindentation, which require small sample sizes, can both be used to reliably analyze geomechanical properties in circumstances where larger shale samples are not available from borehole zones of interest.

Item Type:	Article
Uncontrolled Keywords:	Shale assessment Rock-Eval geochemical screening geomechanics measurement analytical techniques sample size considerations correlative microscopy
Subjects:	Rock Testing
Divisions:	UNSPECIFIED
Depositing User:	Mr. B. R. Panduranga
Date Deposited:	27 Mar 2023 05:33
Last Modified:	27 Mar 2023 05:33
URI:	http://cimfr.csircentral.net/id/eprint/2573

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