川东北地区胡家坝震旦系灯影组古油藏特征及其油气勘探意义

四川盆地东北缘米仓山前带胡家坝灯影组古油藏主要分布于灯影组四段，越靠近顶部丰度越高，储层沥青主要为油层沥青和运移沥青。油源对比分析表明，胡家坝灯影组古油藏油气主要来自于侧向的优质筇竹寺组烃源岩，不排除灯影组三段泥质烃源岩供烃的可能。川东北地区筇竹寺组烃源岩在晚志留世进入初期生油阶段；在二叠纪末进入生油高峰，此时油气侧向运移至胡家坝灯影组储层中形成古油藏；在中三叠世有机质演化进入高成熟阶段，古油藏中原油裂解；晚白垩世至今，构造抬升剥蚀使得古油藏遭到破坏，形成现今残留古油藏。胡家坝灯影组古油藏的发现对四川盆地震旦系灯影组油气勘探有重大意义。灯影组四段主要为一套台缘丘滩相沉积，优质储层发育，以一、二类储层为主，灯影组四段上覆筇竹寺组作为区域和直接盖层，封盖条件好，表明川东北地区震旦系灯影组具有较好的勘探潜力。

Feature of paleo-oil pools in the Sinian Dengying Formation,northeastern Sichuan Basin,and its significance to exploration

The paleo-oil pools concentrate on the 4th member of Dengying Formation (Deng 4 member) in Hujiaba section in the piedmont of Micangshan Mountain at the northeastern margin of Sichuan Basin, and their abundance ever increases towards the top, with reservoir asphalt dominated by reservoir asphalt and migration asphalt.The oil-source correlation analysis shows that the hydrocarbons in the paleo-oil pools of Dengying Formation in Hujiaba section are mainly sourced from high-quality source rocks in the Qiongzhusi Formation, perhaps together with source rocks in Deng 3 member.The source rocks in the Qiongzhusi Formation, Northeastern Sichuan Basin entered the early oil-generation stage in the Late Silurian and reached the oil-generation peak at the end of Permian.At this time, the hydrocarbons migrated laterally to the reservoir of Dengying Formation, forming paleo-oil pools.During the Middle Triassic, the organic matter entered the stage of high maturity, with the crude oil in the paleo-oil pools being cracked into gas.Since the Late Cretaceous, the tectonic uplifting and denudation have destroyed these paleo-oil pools, leaving the residual paleo-oil pools at present.The discovery of the paleo-oil pools in the study area is of great significance to the hydrocarbon exploration of the Sinian Dengying Formation in Sichuan Basin.The Deng 4 member is composed of mound-shoal deposits formed at the platform margins, developing high-quality reservoirs dominated by TypesⅠandⅡ; while its overlying Qiongzhusi Formation serves as regional and direct caprocks, featuring good sealing capacity.The favorable reservoir-seal combination indicates that high exploration potential exists in the Sinian Dengying Formation, Northeastern Sichuan Basin.