New research progress of Jurassic tight oil in central Sichuan Basin, SW China

Abstract

The resource potential, “fractured” reservoir, reservoir type and stimulation technology of Jurassic tight oil in central Sichuan basin were investigated. Based on the evaluation method of tight oil resource, the amount of oil resources of the five Jurassic layers were estimated at 1.6 billion tons, showing that the Jurassic oil resource potential in central Sichuan Basin is huge. Integrated analysis of static and dynamic data including core-description, thin section examination, well test and exploration show Jurassic reservoirs are fracture-pore reservoir with ultra-low porosity, super-low permeability, rather than single “fractured” reservoir believed before. Jurassic reservoirs are tight oil reservoir with the characteristics of near source charge and continuous distribution. The high-quality hydrocarbon source, reservoir with better physical properties and fracture are the main factors controlling tight oil enrichment. “Horizontal well + volume fracturing” of Shayi Member tight sandstone reservoir and the “horizontal well + fracture acidizing” for the Da'anzhai Member shell limestone reservoir have achieved good stimulation effect. Key words: Central Sichuan Basin, Jurassic, tight oil, resource potential, tight reservoir, enrichment rule, reservoir stimulation