关键词: 川中, 侏罗系, 大安寨段, 凉高山组, 页岩油田, 地质资源量, 技术开采量, 勘探目标

Abstract: The oil area of the Jurassic System in Central Sichuan is regarded as poor mine because no breakthroughs were made in exploration of the area in the past five decades. The main reservoirs are the early confirmed shell limestone of 1st and 3rd interval of Da’anzhai Section (with the porosity being less than 1%). They are identified as fractured oil fields with the geological resources amounting to 11×108t. Later, the reservoirs of muddy shell limestone were found in the area (with the porosity being 1.56%). With the exploration potential boosted, the resources in the area rose to 35×108t. The present study indicates that the average porosity of source strata – 2nd interval of Da’anzhai Section mud shale subzone – is 2.35% while the average porosity of mud shale containing organic matter is 3.8%. Oil and gas were found in drilling. They are the main reservoirs in the area with many high-yield wells drilled. Therefore, the Jurassic System in Central Sichuan is regarded as locally sourced and accumulated shale oilfields. In the semi-deep lacustrine zone of 26000 square kilometers in Central Sichuan, the thickness of mud shale is higher than 40 meters while TOC is 1.5-2%. It is the favorable zone for exploration of shale oil. Based on the volumetric method, the geological resources of shale oil from Jurassic Da’anzhai Section and Lianggaoshan Formation are 164×108t. It is proposed that source strata of Jurassic mud shale should be further studied, establishing an experiment zone of shale oil development in Central Sichuan. Da’anzhai Section of Gongshanmiao and Guihua oilfields as well as Lianggaoshan Formation of Nanchong Structure can be selected for pilot development of shale oil, accelerating the exploration process in this field.

Key words: Central Sichuan, Jurassic System, Da&rsquo, anzhai Section, Lianggaoshan Formation, shale oil field, geological resources, technological production, exploration targets