苏里格气田盒8段河道迁移特征分析及应用

Braided river channel migration characteristics of He 8 formation in Sulige Gasfield

为了明确苏里格气田盒8段辫状河河道迁移特征,有效指导水平井开发,本文以苏里格气田苏东南区召41井区为例,通过观察大量野外露头和岩芯资料,结合区域沉积环境,深入分析测井相类型,描述沉积相和砂体平面展布,重点在密井网区域引入大量水平井实钻资料进行砂体精细解剖,参考前人研究河道沉积砂体宽厚比成果,建立了区块河道砂体宽厚比经验公式,分析认为盒8段砂体横向叠置模式分别为水平搭接、错位叠置、垂向叠置、孤立分布等4种,盒82下、盒81下、盒82上河道的继承性较好,到盒81上时,沉积环境从强辫状河分流河道变化成弱辫状分流河道,河道的继承性变差,从盒82下到盒81上河道整体呈现逐渐萎缩。分流河道(砂体)分布具有明显的继承性和局部的迁移性,继承性表现在不同小层分流河道的大体位置较稳定,迁移性表现在分流河道的具体位置局部重合,有两条主河道汇聚、分叉,有一条主河道两侧迁移,包括东移、西移和往返3种侧向迁移方式。

To clarify the braided river channel migration characteristics of He 8 formation in Sulige Gasfield and efficiently guide horizontal wells,through study of Zhao 41 well block of Sulige Gasfiled,the plane distribution of sedimentary facies and sand body are described by observing extensive field outcrops and core data and thoroughly analyzing logging facies types.An empirical formula of width to thickness ratio of channel sand body for gas block in Sulige Gasfield is established by analyzing a large number horizontal wells data in dense well pattern area and previous research results of width and thickness ratio.By analyzing,sandstone horizontal superimposed structures in He 8 formation are horizontal overlapping,dislocation superimposed,vertical superimposed,and isolated distribution respectively.The sand body succession of He 8 Xia 2,He 8 Xia 1,He 8 Shang 2 and He 8 Shang 1 are good.At He 8 Shang 1,sedimentary environment changes from strong braided distributary channels into weak braided distributary channels and the succession of river channel turns worse.Besides,the whole river channel gradually shrinks from He 8 Xia 2 to He 8 Shang 1.As a whole,obvious sand body succession and limit migration are typical characteristics of distributary channel(sand body)distribution.The succession is presented by the stable location of distributary channels in different sublayers.The migration is presented by local overlapping of distributary channels,the convergence and bifurcation of two main channels,and the migration of one main channel to both sides,including 3 kinds of lateral migration-east,west and roundtrip.