层序地层特征与油气成藏关系——以塔中4油田为例

 将层序地层学理论与油气成藏理论相结合,从层序特征、沉积体系和油气成藏条件等方面探讨了塔中4油田CI油组层序地层特征与油气成藏模式。综合利用地震、测井及岩心资料,开展塔中4油田CI油组层序地层学研究,将其划分为2个三级层序、5个准层序组、9个准层序。在层序地层格架内进行沉积特征研究,确立研究区发育潮坪和三角洲两类沉积体系。在层序及沉积特征研究基础上,对油气成藏的要素进行分析,确立沿断输导它源成藏模式。CI油组本身烃源岩不发育,油气主要来源于下覆奥陶和寒武统烃源岩。储集层主要分布在SQ1及SQ2的海侵体系域。油气从烃源岩中沿着大断裂向上运移到CI油组成藏,发育有岩性、断层-岩性及微背斜3种类型油气藏。

Relationship Between Characteristics of Sequence Stratigraphy and Hydrocarbon Accumulation on CI Oil Formation of Tazhong 4 Oilfield

Combined with the theory of sequence stratigraphy and hydrocarbon accumulation, the characteristics of sequence stratigraphy and hydrocarbon accumulation mode of CI oil group in Tazhong 4 oilfield are discussed which is based on the sequence characteristics and sedimentary system and hydrocarbon accumulation conditions,etc. Using the datum of seismic, well logging and coring, CI oil group in Tazhong 4 oilfield can be divided into 2 third-order sequences, 5 subsequences units, 9 parasequences, and both tidal and Delta depositional systems have been identificated by research of faces in the trellis of sequence stratigraphy. On the basis of the sequence and sedimentary characteristics, hydrocarbon accumulation elements of petroleum geology are analyzed, and hydrocarbon accumulation along the fault-transporting allochthonous model has been established. For hydrocarbon sources rocks are hardly found in CI oil group,oil and gas comes mainly from the underlying Ordovician and Cambrian source rocks,reservoirs are mainly distributed in transgressive system tracts of SQ1 and SQ2. Oil and gas along the big break migrated up to CI oil group and accumulation. There types of reservoirs of lithologic hydrocarbon, faults-lithologic hydrocarbon and micro-anticline are developed.