天然气资源评价重点参数-可采系数研究

通过对天然气藏的类型、可采系数的影响因素、不同气藏可采系数的取值标准及中国陆上四大含气盆地的可采系数等方面的研究,认为:主要依据岩性和驱动类型建立简便可行的天然气藏分类,气藏可分为碎屑岩气驱、碎屑岩水驱、碳酸盐岩气驱、碳酸盐岩水驱和致密气藏;可采系数的影响因素主要是地层水的活跃程度、储层的渗流条件、废弃地层压力等;碎屑岩气驱气藏的可采系数为75%～90%、碎屑岩水驱为50%～70%、碳酸盐岩气驱为80%～95%、碳酸盐岩水驱为55%～80%和致密气藏为40%～55%;四川、鄂尔多斯、柴达木和塔里木盆地可采系数分别为:50%～60%、55%、50%～60%和70%.

The Study on Key Parameters of Natural Gas Resource Evaluation -the Study of Recovery Rate

Recovery rate is one of key parameters of natural gas resource evaluation, which is important to natural gas recoverable resource calculation. By the study of the natural gas type and the influence factor and the recovery rate of the different natural gas reservoir and so on, much achievement has obtained. First, according to their lithology and drive type, natural gas reservoirs are divided into gas drive-clastic reservoirs, water drive-clastic reservoirs, gas drive-carbonate reservoirs, water drive-arbonate reservoirs, and tight reservoirs. Second, recovery rate is influenced by formation water activity, reservoir permeability, abandoned strata pressure, etc. Third, recovery rate of gas drive-clastic reservoirs is 75%-90%, water drive-clastic ones 50%-70%, gas drive-carbonate ones 80%-95%, water drive-carbonate ones 55%-80%, tight ones 40%-55%. Forth, new standard stands the test of actual data of natural reservoirs. In the end, recovery rate of natural gas in 4 main gas-bearing basins are analyzed and the results are: recovery rate of natural gas in Sichuan Basin is 50%-60%, Ordos 55%, Qaidam 50%-60%, Tarim 70%.