海拉尔盆地乌尔逊-贝尔凹陷油气成藏条件及有利勘探区预测

乌尔逊-贝尔凹陷是海拉尔盆地中沉积岩最厚、面积最大的2个凹陷,该区油气资源十分丰富,但构造复杂,断裂发育,油气勘探风险较大.针对乌尔逊-贝尔凹陷的油气成藏规律复杂的问题,从烃源岩特征、储层特征、盖层特征及生储盖组合特征、油气运移条件、圈闭特征和油气运聚期次及成藏过程等方面研究该区的油气成藏条件,认为该区暗色泥岩厚度大、横向变化快,以大一段-南屯组最为发育;砂岩和砂砾岩是最重要的储集岩体,浊流沉积和三角洲沉积是发育储集岩体的最重要相带;大一段是该区的区域性盖层,南一段和伊一段构成局部盖层,生储盖组合有下生上储型、自生自储型和上生下储型3种类型,油气主要沿断裂运移到小面积构造圈闭中聚集成藏.预测出有利油气勘探区为苏仁诺尔断裂带、巴彦塔拉构造带、乌南次凹、苏德尔特构造带、呼和诺仁构造带、敖瑙海次凹、贝西次凹和霍多莫尔构造带.

Study on oil and gas reservoir formation conditions of Wuerxun——Beier sags in Hailaer Basin and prediction of the favorable exploration areas in the sags

Wuerxun Sag and Beier Sag are the two sags of larger sedimentary thickness and area,being of developed faults and rich in oil & gas resources.But their exploration risk is very great due to their complicated geological structure.The oil and gas reservoir formation conditions of the sags are researched from the aspects of source rock characteristics,reservoir characteristics,cap rock characteristics,source-reservoir-cap rock association,hydrocarbon migration conditions,trap characteristics and hydrocarbon migration periods and hydrocarbon accumulation process.The studied results show that,the thickness and lateral variation of the dark mudstone in the studied area is very great,which is very developed in K1d1-K1n;sandstone and glutenite are the important reservoir bodies,they are developed mainly in turbidity current deposit and deltaic deposit;the stratum of K1d1 is the regional cap rock,and the stratums of K1n1 and K1y1 are the partial cap rock,and there are three types of source-reservoir-cap rock association:overlayer producing and underlayer-reserving,underlayer producing and overlayer-reserving,and self-producing and self-reserving,oil & gas migrates through faults and accumulates in small structural traps.It is held that the favorable exploration areas are Surennuoer fault zone,Bayantala structural zone,the southern sub-sag of Wuerxun sag,Sudeerte & Huhenuoren structural zones,Aonaohai sub-sag,the western sub-sag of Beier sag and Huoduomoer structural zone.