渤海湾盆地车镇凹陷古近系层序地层与隐蔽油气藏

综合利用钻井、古生物、测井和地震资料,将车镇凹陷古近系沙三段-东营组沉积划分为沙三-沙二下、沙二上-东营组2个二级层序,以及沙三下、沙三中、沙三上-沙二下、沙二上-沙一、东三段、东一、二段等6个三级层序.深断陷型三级层序的发育主要受控于多期幕式断陷作用,断陷活动强烈,物源供给充足,深水环境优质生油岩发育,低位域扇体类型多样,层序内体系域构成模式有利于隐蔽油气藏形成.沙三上亚段-沙二下亚段地层为典型的深断陷型三级层序,可划分为低位体系域、湖侵体系域和高位体系域,该时期埕南断层活动强烈,物源供给充足,持续型陡岸沉积特点突出.详细研究了层序对沉积的控制作用、各体系域时期沉积体系发育特点、有利砂体的展布规律.对该时期车镇凹陷隐蔽油气藏有利区带进行预测,提出了4种类型的10个有利区带.

Sequence Stratigraphy and Subtle Hydrocarbon Reservoir of Paleogene in Chezhen Sag, Bohai Bay Basin

Based on comprehensive study of outcrops, drilling data, ancient life, well logging and seismic data, the Paleogene Es_3-Ed strata of the studied area were divided into two secondary sequences(Es_3-EsL_2, EsU_2-Ed), and six third class sequences(EsL_3, EsM_3, EsU_3-EsL_2, EsU_2-Es_1, Ed_3, Ed_(1-2)). The deep-faulted third class sequence was mainly controlled by the episodic fault depression and are ideal for subtle hydrocarbon reservoirs for their strong rifting activity undergone, abundant sediment supply, rich and excellent source rocks, as well as for their lower-stand fan facies, sequence style and favorable tract making-up models. The upper part of Es_3 to the lower part of Es_2 is a typical deep-faulted third class sequence that can be further divided into LST, TST and HST system tracts. In this sequence, rifting activity was strongest, sediment supply was abundant, depositional features of continuous steep slope was typical. The control of the sequences on sedimentation, the characteristics of the sedimentary system and the spatiotemporal distribution of favorable sandstone bodies are discussed. Favorable districts for subtle hydrocarbon reservoirs are predicted and ten favorable districts of four different types are outlined.