断块型沉火山碎屑岩致密气藏有效储层控制因素及分布规律——以松辽盆地南部王府气田白垩系沙河子组为例

Controlling factors and distribution pattern of effective tight gas pools in blocky pyroclastic rocks in the Cretaceous Shahezi Formation in Wangfu gas field, southern Songliao Basin

曾凡成 张昌民 李忠诚 张国一 张驰 王拥军 孙文铁 邓庆杰

Fancheng Zeng Changmin Zhang Zhongcheng Li Guoyi Zhang Chi Zhang Yongjun Wang Wentie Sun Qingjie Deng

沉火山碎屑岩致密气属于特殊的复杂岩性非常规气藏，目前研究程度和勘探开发程度低。松辽盆地王府断陷沙河子组发育断块控制的沉火山碎屑岩致密气藏，由于兼具断块、沉火山碎屑岩、致密气藏的复杂性，对储层发育控制因素认识不清导致气藏勘探开发难度极大。采用多种技术手段，在评价沉火山碎屑岩致密气藏特殊性和储层岩性、储集空间、孔隙结构、物性和有效性特征基础上，分宏观气藏、中观砂体及微观储层3个层次，揭示了研究区源-储关系、成藏要素、层间非均质、层内非均质和微观成岩作用对有效储层发育特征的影响，形成了构造控制成藏圈闭、断层控制运移通道、砂体控制气藏分布、非均质性控制层内气水关系、成岩作用控制甜点富集的认识。在此基础上进一步揭示有效储层平面上沿缓坡带由东向西整体呈树枝状发散分布，垂向上为丘状岩体控制下的块状、反韵律分布等规律。研究成果在城深6井区开发井位部署、老井复查中取得较好效果，为类似复杂致密气藏的勘探部署和分类精细开发提供参考。

Tight gas pyroclastic rock reservoirs are special unconventional gas reservoirs with complex lithology that call for in-depth research and more exploration.Those developed in the Shahezi Formation of Wangfu Fault Depression, Songliao Basin, are found to be challenging with fault blocks as their major control coupled with confusing features of sedimentary pyroclastic rocks and tight gas reservoirs.Limited understanding of the controlling fault blocks has hindered the exploration of the reservoirs.In this study, various techniques were used to evaluate the unique features of the reservoirs, including lithology, storage space, pore structure, physical properties and reservoir effectiveness, with a view to revealing the impact of source rock-reservoir interaction, hydrocarbon pooling elements, interlayer and intra-layer heterogeneities, and micro-diagenesis on the development of effective reservoirs from macroscopic (i.e.gas pools), mesoscopic (i.e.sand bodies), and microscopic (i.e.reservoirs) perspectives.We concluded that the traps, migration channels, gas pool distribution, gas-water contact and sweet spot distribution of the reservoirs in the area are conditioned by structures, faults, sand bodies, intra-layer heterogeneity and diagenesis, respectively.In addition, the lateral distribution of the reservoirs can be likened to branches of a tree along gentle slope zones from east to west; while vertically, the reservoirs are blocky and anti-rhythm distributed under the control of some hummocky rocks.The conclusion was applied to the well emplacement and mature well reevaluation in the Chengshen 6 well-block and yielded positive results, thus can be used for reference for the exploration, deployment, and classification of similar tight gas reservoirs in other areas.

10.11743/ogg20210217