辫状河—曲流河河型转换前后砂体差异性研究——以东营凹陷东辛地区东二段为例

Research on sand body differences before and after river pattern conversion from braided river to meandering river:a case study of Dong 2 Member of Dongxin area,Dongying Depression

不同河流相砂体形态特征和分布规律差异较大,河型的转换主控了不同时期砂体平面分布特征、几何参数及纵向叠置关系,进而决定了不同河流相类型储层的油气勘探与开发策略。基于东营凹陷东辛地区东二段岩心、测井曲线、三维地震等资料,借助定量岩心沉积构造、定量地震地貌等方法,得出以下结论:1)东二段4,3,2砂组主要发育辫状河沉积,1砂组主要发育曲流河沉积。2)东二段4,3,2砂组辫状河平均河道深度分别为17~52,20~59,19~52 m,平均河道宽度分别为1589~11602,2154~14597,1862~11923 m,定量地震地貌分析指示河道带宽度介于1000~7000 m;1砂组曲流河平均河道深度为11~30 m,平均河道宽度为665~4221 m,定量地震地貌分析指示河道带宽度介于700~3000 m。3)东二段4,3,2砂组辫状河砂体垂向以接触叠置式、下切叠置式为主,横向以独立接触式、侧切接触式、对接接触式为主;1砂组曲流河砂体垂向以分隔叠置式为主,横向以独立接触式为主。明确砂体几何形态及时空切叠方式,为东辛地区东二段河流相砂岩储层的勘探与开发提供了实际支撑。

There are great differences in the shape characteristics and distribution laws of sand bodies in different fluvial facies,and the conversion of river pattern controls the plane distribution characteristics,geometric parameters and vertical overlapping relationships of sand bodies in different periods,and thus determines the oil and gas exploration and development strategies of different fluvial facies reservoirs.Based on the core,logging curve and three-dimentional seismic data of Dong 2 Member of Dongxin area in Dongying Depression,and with the help of quantitative core sedimentary structure and seismic geomorphology,it is clarified that:(1)The braided river deposits are developed in sand groups 4,3,and 2 of Dong 2 Member,and meandering river deposits are mainly developed in sand group 1.(2)The average channel depth of braided river in the sand groups 4,3,and 2 of Dong 2 Member is about 17-52 m,20-59 m,and 19-52 m respectively,and the average channel width is about 1589-11602 m,2154-14597 m,and 1862-11923 m respectively.The quantitative seismic geomorphology indicates channel width of 1000-7000 m.The average channel depth of meandering river in the first sand group is 11-30 m,and the average channel width(Wc)is 665-4221 m,and the width of channel zone is 700-3000 m as indicated by quantitative seismic geomorphology.(3)The braided river sand body of sand groups 4,3,and 2 in Dong 2 Member is dominated by contact superposition and bottom cut superposition vertically,and is dominated by independent contact laterally,side cut contact and butt contact.The sand bodies in sand group 1 is dominated by divided superposition vertically,and is mainly independent contact laterally.The geometric shape of sand bodies and their time-space cutting and overlapping modes are clarified,which provides practical support for the exploration and development of fluvial facies sandstone reservoirs in Dong 2 Member of Dongxin area.