从海域-陆地石油地质条件类比分析探索辽河滩海西部油气勘探方向

Oil/Gas Potential Predication of Liaohe Offshore Area Based on Analogical Analysis for Petroleum Geology Between Continental and Subsea

滩海区指辽河盆地向辽东湾延伸被≤5m海水覆盖的浅水区域,是辽河油田重要的油气探区。由于矿权和环保等条件限制,长期以来该类油气区勘探和研究进展迟缓。本次把滩海-陆地作为整体,从构造、地层格架、烃源岩、储层及油藏特征等方面系统解剖滩海西部的油气成藏条件,分析海陆地质条件差异性,通过油气成藏要素类比从已知到未知,探讨滩海区油气勘探潜力。研究发现笔架岭—岭南斜坡带具备岩性油气藏形成的有利条件:斜坡背景下发育多种类型坡折带构成油气运聚指向区;多方向物源导致储集砂体发育;坡折带对砂体分布和沉积相的控制作用明显;斜坡带紧邻生烃洼陷,构成岩性油气藏形成的有利生储盖配置。据此指出,以笔架岭—岭南斜坡带岩性油气藏为重点勘探方向,将会在滩海西部勘探中取得新的突破。该成果一定程度上适用于渤海湾盆地其他油田滩海地区的油气勘探工作。

Offshore area refers to the region covered by 5 meters seawater or less.Liaohe basin extends to Liaodong Bay,and it is a crucial area of oil and gas exploration for Liaohe oilfield.Because of the restrictions such as mining right and environmental protection,oil and gas exploration of this area progressed very slowly in the past although the land part of the basin has been well studied and explored since 1970＇s.The both parts of the land and under sea water are geologically similar concerning theirstructure and sequential stratigraphy.The authors take the offshore and land as a whole,delineate the hydrocarbon accumulation conditions of the area involving in structure,stratigraphic framework,source in the area rocks,and hydrocarbon reservoir.The detailed correlation of the geological conditions was analyzed between the land and under sea.With the analogy of oil and gas accumulation factors,oil and gas exploration potential of the offshore area is predicted.It was indicated that Bijialing-Lingnan slope is the best place to be a lithological reservoir.The related favorable factors are as follows：1）the slope coupled with various slope breaks forms a perfect zone for oil and gas migrating;2）multi-directional provenances resulted in the sandstone-rich region;3）slope belt controls the distribution of sand body and sedimentary facies,resulting in interbedding of the sand-mud deposits;4）the slope belt is adjacent to the hydrocarbon-rich sag,and therefore constitutes a favorable association of source,reservoir,and cap rocks,by which lithologic reservoirs is easy to form.Accordingly,the authors indicate that the lithological reservoir in Bijialing-Lingnan slope belt is the main exploration target in the offshore area.The outcomes can be suitable for the oil and gas exploration of the seashore area in the other oil fields in Bohai Bay basin to some extent.