松辽盆地南部长岭断陷断陷层油气成藏组合特征

Characteristics of hydrocarbon plays in faulted formations, Changling Fault Depression, southern Songliao Basin

松辽盆地南部长岭断陷的断陷层勘探程度低,沉积充填具有“火山—沉积”二元特征,成藏组合类型多,且不同构造带主力成藏组合差异大。从成藏组合类型划分入手,剖析不同成藏组合的差异,分析了长岭断陷研究区火山岩与致密碎屑岩两大类油气成藏组合的特点、分布规律和成藏主控因素,构建了3种成藏模式:(1)营城组火山岩油气成藏组合主要表现为近源、近火山口亚相、断裂输导、区域盖层、继承性古隆起控油气富集;(2)营城组下生上储式碎屑岩成藏组合表现为直接盖层、不整合—断裂复合输导、近源、继承性斜坡带(超剥带)控油气富集;(3)沙河子组源内致密油气成藏主要表现为优势相带、埋深、反转构造带控油气富集。基于成藏主控因素分析,提出了不同类型成藏组合油气评价关键参数及标准,分类分区计算了不同成藏组合的油气富集概率,指出了查干花地区营城组火山岩成藏组合、东岭斜坡带、龙凤山反转构造带以及伏龙泉地区致密碎屑岩成藏组合为下步重点勘探方向,尤其是沙河子组源内致密油气勘探潜力较大。

The sedimentary fill of the Changling Fault Depression in the southern Songliao Basin has the dual characteristics of“volcano-sedimentation”.There are many types of hydrocarbon plays with a low degree of exploration in the faulted formations of the Changling Fault Depression.The major plays are different from one structural zone to another.Starting from the classification of hydrocarbon plays and exploring the reasons for distribution differences,we analyzed the characteristics,distribution rules and main controlling factors of hydrocarbon accumulation in volcanic rocks and tight clastic rocks in the study area.Based on the above findings,we established three pool-forming patterns.(1)The near-source,near-crater subfacies,fault transport,regional caprock,and inherited paleo-uplift jointly controlled the oil and gas enrichment in the volcanic rocks in the Yingcheng Formation.(2)Direct caprock,unconformity-fracture composite transport,near-source,inherited slope zone(super-stripping zone)jointly controlled the hydrocarbon accumulation in the clastic rocks in the Yingcheng Formation.Advantageous facies belt,inverted tectonic belt/slope break zone,burial depth,reasonable arrangement of sand body and oil source fault and regional caprock jointly controlled self-generated and self-storing tight oil and gas enrichment in the Shahezi Formation.Based on the analysis of the main controlling factors of hydrocarbon accumulation,the key parameters and standards of oil and gas evaluation for different types of hydrocarbon plays were proposed.It was pointed out that the volcanic rock plays of the Yingcheng Formation in the Chaganhua area,the tight clastic rock plays of the Yingcheng and Shahezi formations in the Longfengshan,Dongling and Fulongquan area are the key exploration directions.