天环凹陷北部上古生界气水分布主控因素分析

Main-Controlling Factor Analysis of the Upper Paleozoic Gas-Water Distribution in Northern Tianhuan Depression

鄂尔多斯盆地天环凹陷北部地区上古生界气水分布规律十分复杂,主要表现为平面上无统一的气水界面,剖面上气水多层叠置。针对这一问题,通过对该区岩心、构造裂缝观察和显微裂缝观测及构造沉积微相、输导体系、气水分布规律及主控因素的研究,配合地应力与流体势、构造裂缝预测等技术手段,明确了研究区气水分布的主要控制因素,建立了该区天然气成藏模式。研究表明:天然气常富集在地应力相对低值区、构造裂缝密度高值区、分流河道主河道及微幅构造的高部位;水体主要富存于分流河道边部、河道底部及微幅构造低部位;沉积微相类型、裂缝类型及发育程度、地应力的相对高低及微幅构造,是天环凹陷北部上古生界气水分布的主控因素。研究结果可为天环凹陷下一步天然气勘探部署提供依据。

The complicated Upper Paleozoic gas-water distribution in northern Tianhuan Depression of Ordos Basin is mainly characterized by no lateral uniform gas-water interface and overlying gas-water layers in the longitudinal direction.Based on core analysis,structural fracture and microscopic fracture observation,transmission system,gas -water distribution pattern and main-controlling factors,the predictions of geo-stress,fluid potential and structural fracture and other technical means were used to clarify the main-controlling factors for gas-water distribution and establish the corresponding gas accumnlation patterns in this urea.Research indicates that natural usually enriched in the relatively low geo-stress area,high structural fracture density area,drainage line of distributary channel and high-part of micro-structure.The aquifer mainly distributes in the side of distributary channel,the channel bottom and the low-part of micro-structure.Sedimentary microfacies,fracture type and development level,geo-stress and micro-structure are considered as the main-controlling factors for the Upper Paleozoic gas-water distribution in northern Tianhuan Depression.This research could provide certain reference for the further natural gas exploration and development in the Tianhuan Depression.