普光气田高含硫气井溢流压井期间井筒超临界相态特征

针对超临界流体状态下烃类、硫化氢 、二氧化碳的特性，结合ｐ-Ｔ-ρ图版和实际气体状态方程，以及普光气田高含硫化氢、二氧化碳气井的实际情况，计算得出普光气田烃类与硫化氢、二氧化碳构成的混合物的相态图；建立了相应的数学模型，模拟了高酸性高压气井环空温度、偏差因子、压力和体积膨胀情况。从模拟计算结果可以看出： 高含硫气体在溢流压井期间，在井筒较长井段处于超临界状态，远离临界点附近区域，从超临界状态转向低压气态时体积较明显的膨胀但不剧烈，不会出现在超临界点附近处特有的瞬时体积急剧膨胀现象；普光气田气井的酸性气体运移至距地面12%左右（即1 120 m）井深时，有体积膨胀趋势，运移至距地面10%左右（即560 m）井深时有较明显的膨胀特征。

Supercritical phase behavior characteristics of high-sulfur gas at the wellbore during the well overflow

According to the features of CH4, H2S, CO2 in supercritical condition and p T ρ phase diagram with Peng Robinson real gas state equation, and with the consideration of gas wells in the Puguang gas field with high H2S and CO2 contents, the phase diagrams of the hydrocarbons with H2S and CO2 are obtained and the corresponding mathematical model is built to simulate the annulus temperature, Z factor, pressure and volume change of a sour gas well. The simulation results show that the high sulfur gas is in supercritical condition at a much long section of the wellbore during the overflow; while being far away from the neighborhoods of supercritical point, the volume of the gas expands evidently but not acutely when turning to the low pressure state from the supercritical state, and the phenomenon like instantly acute expanding near the supercritical point will never occur. For the wells in the Puguang gas field, acidic gases will tend to expand in volume at the depth of 1120 m from the surface (12% of the well depth) and then present the features of evident expanding when migrating to the depth of 560 m from the surface (10% of the well depth).