鄂尔多斯盆地上古生界流体压力分布与成因

PRESSURE DISTRIBUTION AND GENESIS OF FLUID IN THE UPPER PALEOZOIC OF THE ORDOS BASIN

王胜利 许化政

Wang Shengli Xu Huazheng

中国地质大学(北京), 北京, 100083 2. 中国石油化工股份有限公司石油勘探开发研究院, 北京, 100083

China University of Geosciences, Beijing 100083, China 2. Research Institute of Petroleum Exploration & Development, Petrochina, Beijing 100083, China

鄂尔多斯盆地上古生界的流体压力从一个侧面反映了盆地内的天然气藏类型。深盆气表现为区域的负压异常,且随气层埋藏深度变大和煤层Ro的增大,负压程度越来越大;与构造有关的气藏,则普遍表现为静水压力或正异常压力特征。深盆气的负压特征与区域性的构造抬升剥蚀有关,负压程度的不同则受煤层成熟演化程度的控制。盆地腹部高演化程度区的煤层高生气强度和地层水的高汽化程度,使盆地腹部天然气"湿度"小,比重小,压力系数低;向盆地边缘方向随热演化程度变低,天然气"湿度"变大,比重变大,压力系数升高。深盆气区压力系数的规律性变化反映了天然气近距离运移和就地成藏的特征。

The fluid pressure in the Upper Paleozoic of the Ordos Basin reflects the type of gas reservoir from one aspect. The deep gas reservoir has the negative abnormal pressure, and with rises of the buried depth and Ro value of coal layer, the negative abnormal pressure would rise correspondingly. The gas reservoir in connection with the structure shows hydrostatic pressure or positive abnormal high pressure. The negative abnormal pressure is related to the regional structure uplift denudation and the pressure is controlled by evolution degree of maturation. The high gas generation of the coal layer and high vaporization in high evolution zone caused the low nature gas moisture, low gravity and low pressure coefficient in the center of the basin. With the lower thermal evolution at the basin magin, the nature gas moisture, gravity and pressure coefficient will be higher. The regular variation of pressure coefficient in the deep gas accumulation reflects the short distance gas migration and in-situ gas reservoir formation.

国家科技重大专项“中西部重点碎屑岩领域油气富集规律与分布预测”(2008ZX05002—006)资助

https://doi.org/10.11781/sysydz201006536