四川盆地龙岗与元坝地区礁滩成藏对比分析

四川盆地长兴组—飞仙关组礁滩油气资源丰富,川东北台地—台缘斜坡地区是礁滩油气资源分布与勘探的重点地区。川东北龙岗与元坝地区礁滩气藏成藏条件优越,气藏分布受沉积相带、储层发育特征、白云石化与构造作用等因素控制;气藏类型多样,储集性、裂缝发育程度和构造活动性是富集高产的重要控制因素。目前元坝地区勘探成效好于龙岗地区,主要由于元坝地区礁滩规模较大、非均质性较弱、受潮道系统影响较小等原因,表现出更优越的气藏形成与富集条件;龙岗地区受构造作用与潮道系统影响显著,储层非均质性与气藏后期调整改造强烈,"一礁一滩一藏"特征明显。研究认为,地震资料品质攻关、沉积微相精细研究、储层预测与油气检测是进一步提高龙岗与元坝地区礁滩气藏勘探成效的工作重点,台缘区厚度大、面积大的礁滩体是重点勘探目标。

Comparison and Analysis of Reef-bank Gas Reservoirs in Longgang and Yuanba Areas in Sichuan Basin

The Changxing Formation and Feixianguan Formation in Sichuan Basin are enriched in reef oil and gas resources, which are distributed in the areas of the platform and the platform margin slope in northeast Sichuan Basin. This region is an important area for exploration. The reef-bank gas reservoirs in Longgang and Yuanba areas of northeastern Sichuan Basin have good conditions for accumulations. Distribution of the gas reservoirs are controlled by a number of factors, such as the sedimentary facies, reservoir development eharaeteristies, dolomitization and tectonic action. The important controlling factors for abundance and high production also include the variety of gas reservoirs, fractural development degree and structural activity. At present, the exploration results in Yuanba area are better than those in Longgang area, because the reef-bank scale is larger in Yuanba area with a weaker heterogeneity. The area is less affected by the tidal channel systems. Therefore, Yuanba area has better conditions for accumulation and abundance. Longgang area is apparently affected by the structural effect and tidal channel systems. The reservoirs are strong in heterogeneity and experience strong adjustment and transformation in later periods. The area is characterized as a number of isolated reef beach reservoirs. The study indicates that the efforts should be focused on seismic data quality, further research on the sedimentary subfacies, reservoir prediction and oil and gas testing to improve exploration of reef- bank gas reservoirs in Longgang and Yuanba areas. The reef-bank bodies in the platform peripheral area, with a large thickness and a large area, should be the important targets for exploration.