涠西南凹陷A区块流一段下层序湖底扇沉积微相及优势储层

Sedimentary microfacies and dominant sand bodies of lower sequence sublacustrine fan in L1 Formation of Block A,Weixi’nan Sag

涠西南凹陷流一段湖底扇沉积砂体已成为目前重要的勘探开发目标之一,但是湖底扇砂体岩性和微相类型在平面上变化快,纵向上也存在多期砂体叠置特征,刻画优势储层展布是目前开发的难点之一。以重力流沉积理论为指导,结合区域构造特征及古地貌分析,通过岩心观察、粒度分析、测井和三维地震等资料,对涠西南凹陷流一段下层序湖底扇沉积微相特征进行了分析,在研究区识别出6种沉积微相,不同沉积微相在岩性、岩心、测井和地震相上均表现出不同特征,由此建立了本区沉积微相识别图版。通过岩石物理分析,泊松阻抗属性在区分储层和非储层方面优于横波阻抗和纵波阻抗属性,同时对多种地震属性进行优选,认为均方根振幅属性能很好地反映优势储层,由此精细刻画出目标区优势储层展布范围,研究成果指导了开发井位部署,并在后续开发井实施中得到了验证。

Sublacustrine fan sedimentary sand bodies have become one of the important exploration and development targets at present,but the lithology and microfacies types of sublacustrine fan sand bodies change rapidly on the plane,and there are also multi-stage superposition characteristics in the longitudinal direction,so it is one of the difficulties to describe the distribution of dominant sand bodies.Guided by the theory of gravity flow sedimentation,combined with regional structural characteristics and paleo-geomorphological analysis,the sedimentary microfacies characteristics of the lower sequence sublacustrine fan in L1 Formation in the Weixinan Sag were analyzed through core observation,grain size analysis,logging,and 3D seismic data,and six sedimentary microfacies are identified in the study area.Different sedimentary microfacies show different characteristics in lithology,core,logging and seismic facies,thus establishing the identification chart of sedimentary microfacies.Through petrophysical analysis,poisson impedance attribute is superior to S-wave impedance and P-wave impedance attribute in distinguishing reservoirs and non-reservoirs.At the same time,multiple seismic attributes are optimized,and the Root Mean Square amplitude attribute can reflect the dominant reservoirs.Therefore,the distribution range of dominant reservoirs in the target area is described in detail,and the research results provides a good guidance for the deployment of development well locations,and have been verified in the implementation of subsequent development wells.