Reservoir characterization of the shallow to deep Longmaxi formation in the Weiyuan Block, southwestern Sichuan Basin

Marine shale gas exploration targets are reaching into shallow to deep or ultradeep burial depths. Rock microstructure and reservoir quality emerge as the main risk considerations for a profitable at these large Shallow marine shales occur in Silurian Longmaxi Formation of Weiyuan Block, which is located on southwestern margin Sichuan Basin. However, few details characteristics this Block have been reported. In study, five wells approximately 3500 m were drilled. Field emission scanning electron microscopy, low-pressure adsorption core plug porosity-permeability measurements conducted 6 (2651–2940 m) 11 (3539–3575 samples obtain organic geochemical characteristics, mineral constitutions, pore structures petrophysical properties, they major controls quality. The results show similar mineralogical all from various Both mainly composed quartz, carbonate clays total carbon (TOC) content more than 2 wt.% mean S 1 + value 52 mg/g. Source rock criteria using TOC suggest most fall excellent source rocks. mostly siliceous rocks that contain pores, intraparticle dissolution interparticle quartz pores clay play positive role improving Pore surface area volume increase with increasing TOC, indicating porous fraction control structure porosity. We suggested formation belongs high-quality an average 3.9 well-developed networks, should be important target exploration.