华池-庆阳地区延长组长6-长7油层组浊积岩特征及成因

Characteristics and genesis of turbidite of Chang 6 and Chang 7 oil reservoirs in Huachi-Qingyang area of Ordos Basin,China

利用钻井岩心、测井及地震资料,对鄂尔多斯盆地华池-庆阳地区三叠系延长组长6-长7油层组沉积过程中所发育的浊积岩特征及成因进行了系统深入的研究。其特征主要表现为:底铸型构造普遍发育,复理石韵律明显,具有典型的鲍马序列,粒度分布平行于C=M基线,萨胡判别值平均为7.357;同时,根据沉积背景的差异,将研究区浊积岩划分为来源于东北缓坡背景三角洲前缘的浊积岩及来源于南部、西南部陡坡背景三角洲前缘的浊积岩两种成因类型。在上述研究基础上,比较了两类浊积岩在成因机制、发育规模、砂体形态、岩相特征等方面的差异,并建立了不同沉积背景下的浊积岩成因模式。

The paper uses the data of drilling cores, logging and seism in study area to research the turbidite features in detail developed during the deposition of Member 6 and Member 7 of the Upper Triassic Yanchang Formation （Chang 6 and Chang 7） oil reservoirs in the Huaehi-Qingyang area of Ordos Basin in China. The features include the bottom cast general development, the obvious flysch rhythms, the typical Bouma sequence, size distribution of paralleling to the C=M baseline, and the Sahu discrimination value of 7. 357. According to the different provenances, the turbidite types are classified as two types： （1） one comes from the northeast gentle slope delta front; （2） another comes from the south and southwest steep slope delta front. Furthermore, based on the above, the paper compares the differences between the two types of turbidite in formation mechanism, size, sand body morphology and litho facies and establishes the genetic model of the turbidite under different depositional settings.