东营凹陷沙三段源岩排烃特征及潜力评价

THE HYDROCARBON-EXPULSION CHARACTERS AND THE POTENTIAL RESOURCE EVALUATION OF THE 3RD MEMBER OF SHAHEJIE FORMATION IN DONGYING SUB-DEPRESSION

东营凹陷透镜体岩性油气藏主要分布在沙三中亚段,但沙三中亚段烃源岩能否成为有效油气供给源岩一直存在争议。根据排烃门限理论,利用生烃潜力法对东营凹陷沙三段上、中、下三个亚段烃源岩的排烃特征进行了研究并对其资源潜力进行了评价。沙三上、中、下三套烃源岩的主要排烃期均为明化镇组沉积时期,排烃门限深度分别为2500m,2650m和2600m。三套烃源岩的总排烃量和总资源量分别为58.41×108t和25.12×108t,其中沙三下亚段烃源岩的排烃量和资源量均占总数77%以上,而沙三中亚段占16%,沙三上亚段则仅为7%。综合分析认为,沙三下亚段为岩性油藏的主力烃源岩之一,沙三中亚段对岩性油藏成藏贡献不大,为非主力烃源岩。

The 3rd member of Shahejie Formation is contestable as hydrocarbon source rocks,though it is the main formation in which the lenticular lithologic reservoirs develop.In this paper,based on the theory of hydrocarbon-expulsion threshold,the hydrocarbon-expulsion characters and the potential source evaluation of the upper,middle,lower sections within the 3rd member of Shahejie Formation are discussed.In the upper,middle and lower sections within the 3rd member of Shahejie Formation,there were the same main period of hydrocarbon expulsion and the hydrocarbon-expulsion threshold depth of 2 500 m,2 650 m,2 600 m respectively.The total hydrocarbon-expulsion and the total sources in the three sections are 58.41×108 t and 25.12×108 t,in which the lower section holds more 77%,and the middle and the upper sections hold 16% and 7% respectively.The conclusions can be made depending on the comprehensive analyses that the lower section is the one of the main hydrocarbon source rocks and the middle section,due to its little contribution to the lithologic pools,is not the main hydrocarbon source rocks in Dongying sub-depression.