鄂尔多斯盆地北缘近源砂砾质辫状河砂体构型与含气性

Sand body configuration and gas-bearing properties of near source sand-gravel braided river on the northern margin of Ordos Basin

齐荣 李良 秦雪霏

QI Rong LI Liang QIN Xuefei

1. 中国地质大学(北京) 海洋学院, 北京 100083; 2. 中国石化 华北油气分公司 勘探开发研究院, 郑州 450006

1. School of Ocean Sciences, China University of Geosciences, Beijing 100083, China; 2. Research Institute of Exploration and Development, SINOPEC North China Oilfield Company, Zhengzhou, Henan 450006, China

鄂尔多斯盆地北缘杭锦旗地区独贵加汗一带的二叠系下石盒子组盒1段沉积期处于公卡汉古陆的南坡，形成了一套近物源的砂砾质辫状河沉积。河道砂体的物性与含气性具有良好的相关性，但河道砂体内部的非均质性很强，造成含气性差异也大。对该区盒1段砂砾质辫状河砂体构型进行了分析研究，明确了其岩相特征和主要构型单元。通过岩心观察和测井资料分析，在盒1段划分出6种典型岩相，心滩和水道充填为主要构型单元。心滩砂体在纵向上一般具有Gm-Sgt-Sm、Gm-Sm-Sp、Sgt-Sm、Sm-Sp等4种岩相组合，水道充填砂体一般具有Gm-Sp、Gm-St、Sgt-Sp、Sgt-St等4种岩相组合，砂体内部这种岩相变化是形成强非均质性的主要原因。利用直井、水平井和地震资料统计心滩长度为230～1 050 m，根据经验公式计算心滩宽度为43～386 m。心滩砂体与水道充填砂体侧向共生，但其物性和含气性有明显差异。统计资料表明，心滩砂体的物性和含气性优于水道充填砂体。

The first member of the Lower Permian Shihezi Formation in the Duguijiahan area of the Hangjinqi region on the northern margin of Ordos Basin was deposited on the southern slope of Gongkahan paleocontinent, forming a set of sand-gravel braided river deposits near the provenance area. The physical properties of sand bodies are well correlated with gas-bearing properties; however, the heterogeneity of channel sand bodies is very strong, resulting in great differences in gas-bearing properties. The sand body configuration of the sand-gravel braided river in the 1st member was analyzed. The lithofacies characteristics and main configuration units were clarified. Through core observation and logging data analysis, six typical lithofacies were classified in the 1st member, with channel bar and braided channel as the main configuration units. The channel bar generally has four lithofacies assemblages:Gm (gravel massive bedding)-Sgt (gravel-bearing sandstone trough cross bedding)-Sm (sandstone massive bedding), Gm-Sm-Sp (sandstone parallel bedding), Sgt-Sm and Sm-Sp. The braided channel generally has four lithofacies assemblages:Gm-Sp, Gm-St, Sgt-Sp and Sgt-St. This lithofacies changes are the main reason for the strong heterogeneity. The statistical data from vertical wells, horizontal wells and seismic data show that the length of the channel bar is 230-1 050 m. According to empirical formulas, the width of the channel bar is 43-386 m. The channel bar sand body and braided channel sand body are laterally symbiotic, but their physical properties and gas-bearing properties are obviously different. Statistical data show that the physical properties and gas-bearing properties of channel bar sand body are better than those of the braided channel sand body.

国家科技重大专项“低丰度致密低渗油气藏开发关键技术”（2016ZX05048）；中国石化科技部项目“鄂尔多斯盆地大中型气田目标评价与勘探关键技术”（P17009）联合资助。

https://doi.org/10.11781/sysydz201905682