川西丰谷地区须四段钙屑砂岩含气储层预测

丰谷须四段钙屑砂岩储层具有低伽玛、高电阻、高波阻抗等特点,储层含气后波阻抗值有所降低,但仍高于或接近于泥岩.运用波阻抗、GR联合反演,可以消除泥岩对识别含气储层的影响,并预测出钙屑砂岩段含气储层的平面展布特征.研究认为:联合反演能够识别出8～10 m厚的有效储层,具有较高的纵向分辨率,该方法预测结果的可靠性,取决于参与反演的钻井数量多少及其分布状态,钻井多且分布均匀的地区,运用多井约束反演技术提高预测储层及其含气性的纵、横向分辨率是行之有效的.

Prediction of Calcarenaceous Sandstone Gas-Bearing Reservoir in the 4th Member, Xujiahe Formation in Fenggu Area, West Sichuan Basin

The calcarenaceous sandstone reservoir in the 4th Member of Xujiahe Formation in Fenggu area are of the characteristics of low GR, high resistance and high impedance. The impedance of gas-bearing reservoir, which will reach a lower value than common none-gas-bearing one, is still higher than or close to that of mudstone. By jointly using the reverse of impedence and GR, the influence of mudstone imposing on the gas-bearing reservoirs can be eliminated, and the plane distribution characteristics of calcarenaceous sandstone gas-bearing reservoirs can be predicted. The analysis has come to the conclusion that 8~10 meter thick effective reservoirs can be recognized through joint inversion of impedance and GR therefore such inversion can produce a higher vertical resolution. The credibility of the reservoir prediction mainly depends on the number and distribution of the wells concerning with the inversion process. The method has been successfully applied to improve the vertical and horizontal resolution during the gas-bearing reservoir prediction through multi-well restriction inversion in the area with enough and even-distribution wells.