异常高压含水凝析气藏有效库容影响因素

有效库容是储气库的关键参数,有效库容评价影响储气库的功能定位、调峰规模、建库参数设计以及整体建库方案设计。异常高压含水凝析气藏改建储气库时,异常高压、水侵和反凝析现象影响库容。由于气藏异常高压,储气库设计上限压力为58.00 MPa,远低于原始地层压力,气体体积系数不同,储气库库容也不同;储气库注采运行过程中,水体往复运移对储集空间动用效率具有较大的影响;储气库交替注采过程中,当地层压力低于露点压力时,凝析油析出对库容有一定的影响。针对这一问题,研究建立了改进的物质平衡和数值模拟双模型,以气藏动态储量为基础,定量分析了异常高压、反凝析、水侵等因素对库容的影响,并建立了一套考虑多因素影响的储气库有效库容评价方法。该成果现场应用于轮南59石炭系气藏建库,准确评价了该储气库的有效库容,为轮南59石炭系气藏改建地下储气库建库参数研究奠定基础。

Factors Influencing Effective Storage Capacity of Abnormally-High-Pressure Water-Containing Condensate Gas Reservoirs

As a key parameter, the effective storage capacity of a UGS affects the function, peaking capability, parameters and design of the UGS, so its accurate evaluation is very important. When converting an abnormally-high-pressure water-containing condensate gas reservoir into a UGS, factors such as abnormally high pressure, water intrusion and reverse condensate affect the storage capacity. Considering abnormally high pressure, the upper limit of the pressure for the UGS is designed to be 58.00 MPa, which is much lower than the original formation pressure. The difference of the gas volume coefficient results in the difference of the storage capacity of the UGS. During the injection-production process, water flows back and forth in the UGS, which dramatically affects the utilization of reservoir space. In the alternative production-injection process, when the formation pressure is lower than the dew point pressure, separated condensate oil has a certain influence on the storage capacity. In response to this problem, an improved dual model integrating material balance and numerical simulation was established. Based on the dynamic reserves of gas reservoirs, factors such as abnormal high pressure, reverse condensation, water intrusion were quantitatively analyzed, and a set of methods for evaluating the capacity of the UGS were developed. The set of methods was applied for constructing the Lunnan-59 Carboniferous UGS. The effective storage capacity of the UGS was accurately evaluated. This lays a foundation for the research on the parameters of the UGS, and ensures the successful construction of the Lunnan-59 Carboniferous UGS.