海上埕岛油田河流相砂体内部结构研究

Internal structure of fluvial facies sand body in offshore Chengdao Oilfield

曲流河点坝是河流相沉积中的优势储层,是油田开发的重点目标。由于点坝内部往往发育泥质侧积夹层,易导致剩余油富集;当油田进入高含水期,亟需精细刻画夹层控制下的剩余油分布以提高采收率。因此,需开展点坝内部级次构型研究,明确其内部侧积体的结构特征和展布规律,建立侧积体模型,为油藏数值模拟研究提供地质基础。以胜利海上埕岛油田A区块为例,利用该区块水平井钻遇井段长、资料丰富、生产层位单一的有利条件,开展点坝内部构型解剖研究。首先通过“测井-地震动结合”描述砂体连通体,识别点坝与废弃河道;其次,在对水平井水平段和定向井的侧积层组合识别的基础上,确定侧积层发育模式;再次,采用逐级控制、水平井约束变差函数分析以及侧积层差异化设置,最终建立体现侧积体特征的精细地质模型。该研究成果为海上大井距水平井段平衡筛管等堵水工艺技术研究提供依据。

Meandering river point bar deposits are the prime reservoir of fluvial faces sedimentary and the key target of oilfield development.Because the muddy lateral accretion interlayers are often developed in point bars,the remaining oil is easy to be enriched.When the oilfield enters the high water cut period,it is necessary to accurately characterize the remaining oil distribution under the interlayer control to improve the oil recovery rate.Therefore,it is necessary to study the internal hierarchical architecture of point bars,clarify the structural characteristics and distribution laws of the internal lateral accretion bodies,and establish the lateral accretion bodies model to provide a geological basis for oil reservoir numerical simulation.Taking Block A of Shengli Offshore Chengdao Oilfield for example and using the advantages including long drilled sand-body section along horizontal well,rich information and single production layer,the anatomical study of the internal architecture of the point bars is conducted.The first step of the study is to describe the connectivity of the sand bodies according to"logging-seismic combination"survey and identify the point bars and abandoned rivers.Then,the development pattern of lateral accretion interlayers is determined with the help of combination recognition from both horizontal and orientation wells lateral accretion interlayers.Afterwards,a precision and accurate geological model is generated for describing the lateral accretion bodies by adopting the stepwise control,horizontal well constraint variogram analysis and lateral accretion interlayers differentiation.The research results provide a basis for the research of water blocking techniques such as balanced screen used in offshore large spacing horizontal wells.