Research On The Characteristics Of Hydrocarbon Accumulation In Beidagang-Banqiao Area

This thesis mainly focuses on the hydrocarbon accumulation research of Beidagang-Banqiao area.It includes static and dynamical accumulation process research,rules of hydrocarbon migration and accumulation and accumulation model to guide further exploration.The results show that the third and first member of Shahejie Formation in Banqiao sub-depression is main and subordinate source rock respectively.The maximal hydrocarbon generation rate activation energy is mainly influenced by the content of exinite,sapropelinite and garnacerane.In application of original TOC,HI and TARhc,and sterane parameters,the paleochmate of Banqiao sub-depression is reconstructed.The result is that the climate became colder through the depositional period from the third member of the Shahejie Formation to the first member of the Shahejie Formation.The high plant contribution increased through that period.Reservoir is mainly distributed in the Shahejie Formation and Dongying Formation.Guantao Formation and Minghuazhen Formation are favourable regional cap rocks.The middle and upper part of the first member of the Shahejie Formation and relatively thick mudstone layers of the top part of the third member of the Shahejie Formation are also regional cap rocks.Sandstones and mudstones of the lower part of the first member of the Shahejie Formation and individual oil layer of the second member of the Shahejie Formation were deposited interbeddedly to form a favourable reservoir-cap assemblage.According to depressions and source formations,the crude oil is divided into four categories.The first category distributes in both Banqiao sub-depression and Banqiao slope which is mainly from the third member of the Shahejie Fornation in Banqiao sub-depression,while the oil in Well Qishen-6 is from the third member of the Shahejie Formation in Qikou Depression.The second category distributes in relatively shallow part of high part of Gangxi slope which is mainly from the third member of the Shahejie Formation in Banqiao sub-depression.The third category distributes in both Gangzhong tectonic zone and Qibei slope whose geochemical characteristics are similar to the first category with lighter ?13C value is from the third member of the Shahejie Formation in Qibei sub-depression.Oils in some wells with higher gammacerane index may be from the first and third member of Shahejie Formation in Qibei sub-depression.The fourth category distributes in Qibei slope whose geochemical characteristics are similar to the second category with lighter ?13C and stable carbon isotope composition of individual n-alkanes value.These oils may be from both the first and third member of Shahejie Formation in Qibei sub-depression.The results of geochemical characteristics of sandstone extract show that hydrocarbon accumulations in the study area are maiuly from the third member of Shahejie Formation with minor contribution of the first member of Shahejie Formation.Hydrocarbon migrated through faults and sand bodies.Well Binshen-8 and Well Binshen-18 may be charge points.Oils from Banqlao sub-depression migrated from north to south through Banqiao fault and Dazhangtuo fault and oils from the third member of Shahejie Formation in Qikou sub-depression migrated from south to north through Dazhangtuo fault and Gangdong fault.Two periods of oil and gas charging occurred in this area.Three accumulation models are summarized which are late-stage and near-source accumulation model controlled by source rocks,"ladder" accumulation model controlled by faults and near-source accumulation model controlled by faults.