川西凹陷浅层气藏分布规律研究——以洛带和新场气田为例

The distribution of shallow gas reservoirs in western Sichuan Depression: Examples from Luodai and Xinchang gas fields

1. 中国地震局地质研究所，北京100029;2. 中国石油化工股份有限公司西南分公司，四川成都610081

Institute of Geology China Seismological Bu-Beijing 100029, China

川西凹陷浅层气藏由侏罗系蓬莱镇组、遂宁组和沙溪庙组气藏构成。不同地区、不同组段、不同沉积相的砂体含气丰度差异很大,总体产能以三角洲前缘相砂体为最高,洛带和新场气田的产能几乎集中在几套大型的三角洲前缘相砂体。砂体的含气丰度与砂体的沉积相类型、砂体和断层的配置关系有密切联系。针对这一情况,从石油地质条件、砂体与断层的配置关系、沉积相和地震相特征等角度对洛带和新场气田的含气情况进行了分析。认为断层的渗透性、断层的封堵性是浅层气藏形成的关键因素,断层渗透性好、封堵性差的部位和区域,油气容易在上部盖层附近富集;断层渗透性差、封堵性好的部位和区域,油气不易向上运移,易在下部富集。根据这一油气富集模式,对川西凹陷洛带气田的一个三角洲前缘相砂体进行了含油气性预测,部署的D68井获得了15×104m³/d的测试产量。

Themain pay beds include Penglaizheng, Suining and Shaximiao in western Sichuan depression. Themost of production in Luodai field and Xinchang field almost are from several prodelta facies sands. The gas saturation of sandstone is closely related to sedimentary facies type and the deployment of fault and sand. This paper analyzes the petroleum geology condition and the relationship between the deployment of fault and sand as well as the sedimentary, seismic facies. It is concluded that the permeability and the sealing ratio of a fault are key factors controlling the distribution of gas field. The gas ismore likely tomigrate to the upper sand and accumulate in the upper formation if the sealing ratio of faults is low and the permeability is high, otherwise, gas wouldmigrate to the lower sand and accumulate in the lower formation. According to oil and gas accumulation pattern, a gas bearing sand in prodelta facies of Lu- odai field in western Sichuan Depression has been predicted, a disposed well has got the testing yield of 15. 1463m³/d.