鄂尔多斯盆地苏里格气田有效砂体展布规律与开发方式研究——以苏东南区为例

Distribution laws and development modes of effective sandbodies in Sulige gasfield: Examples from Southeast Sulige block

苏里格气田是中国目前发现并投入开发规模最大的天然气田,也是中国致密砂岩气田的典型代表,具低压、低渗、低丰度、薄储层、强非均质性特点。气井投产后单井产量低、压力下降快、稳产难度大,直接导致气田开发经济效益差。为提高单井产量,改善气田开发效果,获得开发效益,在分析总结苏里格气田水平井先导性试验成功经验的基础上,以苏东南区为研究对象,率先开展致密砂岩砂体展布规律与开发方式技术攻关。通过前期大量观测野外露头特征,结合该区盒8段沉积特征和钻井资料识别砂体横向叠置模式,在密井网区进行砂体精细解剖,运用等高程法精细划分单砂体,采用多方法论证河道带宽度,定量化描述河道砂体,建立区块河道宽厚比的经验公式,为定量化描述河道砂体提供了理论基础。与此同时,详细研究了苏东南区砂体与有效砂体空间和平面展布规律,根据纵向多层段储层分布类型,分区建立3种井型集群化布井模式和3种水平段轨迹差异化设计模式,使气田开发方式更具有针对性,提高了有效储层钻遇率和储量纵向动用程度,整体提升了气田开发水平。

As not only the largest gasfield discovered and developed in China,but also typical tight sandstone one in China,Sulige gasfield is characterized by low pressure,permeability,and abundance,thin reservoir thickness,and strong heterogeneity.Most gas wells are also featured by low production,fast pressure drop,and difficult stable yield after being put into production,leading to poor economic benefits.In order to increase single-well production and field development efficiency,and realize beneficial development,many successful experiences from horizontal-well pilot test in this field were summarized.Then,the distribution laws and development modes of tight sandbodies were technologically summed up,especially in Southeast Sulige block.By outcrop observation,combined with sedimentary characteristics and drilling data of Shihezi 8 Member,we identified the lateral superimposition pattern of sandbody,carried out fine sandbody analysis on dense well areas,finely divided single sandbody by using equal-elevation method,demonstrated the width of river channel belt,and established an empirical formula for width-thickness ratio of river channel in this block,so as to provide theoretical basis for quantitatively describing river channel sandbodies.Meanwhile,we studied the spatial and plane distribution laws of all sandbodies and effective sandbodies in Southeast Sulige block,and established 3 clustered well distribution models of well type and 3 differentiated design patterns of horizontal section track according to distribution of vertical multi-layer reservoirs,so as to make development modes more targeted.As a result,the effective drilling rate and the vertical reserve-producing degree were increased,and the field development level was improved overall.