Characteristics of limestone reservoirs and sedimentary controls: a study in the Sichuan Basin

Le résumé fourni par la source

In 2020, a novel unconventional reservoir exhibiting coexisting oil and gas was discovered within the Leikoupo Formation in the central Sichuan Basin. Characterized by extra-low porosity and low permeability, the genesis of the reservoir pores has not been systematically investigated. This study integrates petrography, XRD, rock pyrolysis, biomarkers, fluorescence microscopy, gas adsorption and CT scanning to elucidate the characteristics of this reservoir and decipher the relationship between reservoir formation and the original sediments. Experimental results indicate that the reservoir space is largely controlled by the primary mineral framework and hydrocarbon generation overpressure, developing clay intergranular pores, organic matter pores and lamination fractures. Mutual adsorption between clay and organic matter facilitates organic matter preservation to a certain extent. However, their heterogeneous distributions contribute to reservoir heterogeneity and induce multi-point hydrocarbon generation. The findings underscore the critical roles of sedimentary differentiation, organic–inorganic interactions and internal hydrocarbon generation dynamics within a closed system in the formation of this unconventional shale reservoir in the Leikoupo Formation. They further emphasize the sedimentologically constrained evolutionary characteristics of the shale reservoir. This study delivers sweet-spot evaluation insights and a conceptual framework for unconventional petroleum research.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.