应用包裹体技术恢复气藏古压力

Calculation of paleo-pressure in gas reservoirs using fluid inclusions

包裹体捕获时的温度和压力反映了油气藏形成时的古温度和古压力,是油气成藏过程研究的一个重要依据。富（CH4）气盐水包裹体是气藏中最主要的一种包裹体类型,对这类包裹体捕获温度和压力的恢复最大的技术难点是其中气体（CH4）含量的精确测定。通过建立CH4气体拉曼位移值与包裹体内压的相关曲线,根据包裹体总体积和成分保持恒定的原则构建迭代计算模型,可快速准确计算出含CH4盐水包裹体的捕获压力。该方法应用于川南隆32井中奥陶统宝塔组微晶灰岩中的包裹体古压力研究,计算结果显示包裹体的捕获压力为884.08～1 249.32 bar,压力系数约为1.3～1.8,证明了包裹体捕获时地层流体为超压状态。

Trapping pressure and trapping temperature of fluid inclusions are important information for the research of petroleum charge history which represents the paleo-pressure and paleo-temperature of gas-oil reservoirs. Gas-bearing （e.g., CH4） inclusions are common in gas reservoirs. The difficulty for the determination of trapping pressure and tem- perature of inclusions is to accurately measure the concentration of methane. We propose a feasible and credible way to calculate inclusion trapping pressures by using an iteration ealculation model based on the hypothesis of constant total volume and composition of intaet inclusions and correlation curves of inclusion pressure at room temperature and the Raman shift of methane gas. The method was applied to paleo-pressure of fluid inclusions trapped in the Baota Forma- tion limestones in well Long32 in the southern Siehuan. Results indicated that the trapping pressure is in the range d 884.08-1 249.32 bar, which is an overpressure circumstance at a pressure factor of 1.3-1.8.