贝尔凹陷油成藏要素空间匹配关系及对油成藏的控制作用

通过贝尔凹陷油成藏要素--南屯组源岩、裂缝及断层圈闭和源断裂的空间匹配关系研究得到，贝尔凹陷裂缝和断层圈闭与南屯组源岩在空间上有4种接触关系，第一种是布达特群裂缝圈闭位于南屯组源岩侧上方，由T₅-T₁源断裂连接；第二种是南屯组断层圈闭位于南屯组源岩内，由T₂₃-T₁源断裂连接；第三种是南屯组断层圈闭位于南屯组源岩外侧，由T₂₃-T₁断裂沟通的砂体连接；第四种是大磨拐河组二段断层圈闭位于南屯组源岩之上，由T₂₃-T₁断裂连接。贝尔凹陷3个成藏要素空间匹配关系对油成藏与分布的控制作用表现在以下3个方面:①南屯组源岩分布控制着油藏分布；②油藏均沿源断裂分布；③圈闭距南屯组源岩距离越近越有利于油藏形成。

Spatial Matching Relation of Oil Reservoir Forming Factors and Its Control Effect on Reservoir Formation in Beir Depression

Beier Depression is one of second tectonic units in Lake Beier depression, development from the bottom of the bed rock of the Upper Triassic Budate Group(T₃b), the Tongbomiao group（J₂t） of Upper Jurassic, Nantun group(K₁n), Damoguaihe group(K₁d) and Yimin group(K₁y) of Lower Cretaceous, Qingyuangang group(K₁q) Formation of the Yimin group and  the  upper Cretaceous. Combined with results of previous studies, this paper considers source rock, trap, and the source fault are main control factors of hydrocarbon accumulation in Beir depression. Oil and gas mainly from dark mudstone of K₁n and source rock with better conditions, to provide sufficient oil source for hydrocarbon migration and accumulation in Beir depression. Traps are mainly two kinds of type, crack traps and fault traps include fault block, fault seal and fault lithologic traps in Beir depression.The reservoirs of T₃b and K₁d and source rocks of K₁n  located in different layers, faults should be oil migration transporting main pathway.By studies on spatial  matching relation of oil reservoir forming factors in Beier depression K₁n source rock, fracture, fault trap and source fault, it was considered that fracture and fault traps had 4 contact relations with K1n source rocks in space in Beier depression. The first is that fracture traps of Budate group are located at the side of the top of K₁n source rocks. They are connected by T₅ -T₁faults. The second is that K1nfault traps are located in K1n source rocks. They are connected by T₂₃-T₁faults The third is that K1n fault traps are located outside of K1n source rocks. They are connected by sand body connected by T₂₃-T₁ aults. The forth is that K₁d₂  fault traps are located above of K₁n  source rocks. They are connected by T₂₃-T₁faults .The control effect of space matching relation of 3 reservoir forming factors on oil accumulation and distribution was showed as follows three aspects. ①Distribution of oil reservoir was controlled by the distribution of K₁n source rock. ②Oil reservoirs are all distributed along source faults. The shorter the distance from trap to K₁n source rock, the better it is to form oil reservoir.