Geological Controlling Factors of Low Resistivity Shale and Their Implications on Reservoir Quality: A Case Study in the Southern Sichuan Basin, China

At the Changning block and at Luzhou block, genetic mechanism of low-resistivity shale its impact on reservoir quality are currently a hot topic world-wide scale. Shale with resistivity lower than 20 Ω·m is widely developed Wufeng-Longmaxi Formation in Southern Sichuan Basin, bringing considerable challenge for prediction using electromagnetic method. This paper discusses mechanisms qualities three types Basin (the block). Three primary elements controlling distribution have been deduced: distributed gravity flow deposits, poor structural preservation conditions graphitization caused by Emeishan basalt. Specifically, (1) <12 was uniformly deposits Basin. High clay mineral contents (especially illite) increased cation exchange capacity irreducible water saturation reservoir, decreasing electrical resistivity. (2) The close to complex fault-fracture zone generally Ω·m, indicating that played an important role wide shale. near NE-trending faults significantly other areas. (3) basalt extensive west which limited block. not affected graphitization. Among shale, type III characterized high quartz content, TOC, porosity, gas content low Although it still favorable exploration target