Effects of Organic Matter Graphitization on Shale Gas Accumulation in the Lower Paleozoic Longmaxi Formation from the Changning Area, Southern Sichuan Basin

Abstract To investigate the characteristics of graphitized shale and influence organic matter graphitization on gas accumulation, Raman spectroscopy analysis, hydrocarbon generation simulation technique, reservoir physical property test, rock mechanics experiment, field emission scanning electron microscopy (FE-SEM) were carried out nongraphitized shales Longmaxi Formation in Changning area, southern Sichuan Basin. The results indicate that is a result thermal metamorphism matter, resistivity generally lower than 10 Ω·m. logging curves low-resistivity wells Wufeng (O3w), Long11 sublayer (S1l11(1))-Long12 (S1l11(2)), Long13 (S1l11(3)), Long14 (S1l11(4)) show box-shaped characteristics, at boundary S1l11(3) S1l11(4) exhibit sharp drop. has great damage to capacity shale, which mainly manifested as following: (1) reduction residual caused by excessive evolution weakens rate faster shale; (2) brittleness increases due from viscoelastic state glassy state; (3) pores clay intercrystalline are destroyed or even disappeared during graphitization, deterioration properties. Graphitized good electrical conductivity, reason for formation study area; (4) early generation, poor properties, unfavorable preservation main factors low content shale. Therefore, it significance strengthen identify area clarifying next exploration direction avoiding risks Lower Paleozoic exploration.