异常高压凝析气顶油藏地质储量计算模型

Computing Model for Geological Reserve of Abnormally High Pressure Reservoir with Condensate Gas Cap

异常高压凝析气顶油藏的气顶油环协同开发过程伴随着复杂的相态变化。综合考虑气顶反凝析、油环溶解气逸出、原生水蒸发、储层岩石弹性膨胀、外部动态水侵等因素,依据体积守恒原理建立了异常高压凝析气顶油藏物质平衡方程。此外在物质平衡方程的基础上采用迭代计算的方法计算出了凝析气顶油藏的原始地质储量,并对影响地质储量计算的各项因素进行了敏感性评价。应用实例表明,以综合考虑各因素得到的地质储量为基准,分别忽略气顶反凝析、油环溶解气逸出、原生水蒸发以及地层岩石膨胀等因素而计算得到的原始天然气地质储量均偏大,误差最大的是忽略气顶反凝析,其次是忽略油环溶解气的逸出,较小的是忽略地层岩石压缩系数和水蒸汽含量。

Complicated phase changes occur during the collaborative development of gas cap and oil ring in abnormally high pressure reservoir with condensate gas cap.The material balance equation for abnormally high pressure reservoir with condensate gas cap is established based on the principle of volume conservation.Moreover,the balance equation consides the influencing factors such as retrograde condensation of gas cap,escaping dissolved gas of oil ring,connate water evaporation,elastic expansion of reservoir rocks,and external dynamic water invasion.Besides,the geological reserve of reservoir with condensate gas cap is calculated in accordance with the material balance equation,and the sensitivity evaluation of the above influencing factors is carried out.Application example shows that,when the influencing factor is respectively neglected,the computational geological reserve of natural gas is bigger than the one obtained by the overall consideration of those factors.Furthermore,the factors impacting the calculated results from high to low are retrograde condensation of gas cap,escaping dissolved gas of oil ring,elastic expansion of reservoir rocks and connate water evaporation.