底水火山岩储气库库容和工作气量主控影响因素定量评价

升平储气库由底水火山岩气藏改建,针对其特殊的地质条件,通过采用纯气区、过渡带、水淹区分区含气饱和度计算有效含气孔隙体积的方法,建立考虑水侵、应力敏感、岩石和束缚水变形影响的储气库三区带库容参数模型,并优化设计了不同运行压力区间迭代求取最大工作气量和对应库容量的计算方法,对不同区带水侵、应力敏感、岩石和束缚水变形多种因素对库容和工作气量影响进行定量评价。结果表明:从区带损失含气孔隙体积来看,过渡带损失最大,纯气区次之,水淹区较小;从不同因素损失含气孔隙体积来看,水侵是主控因素,岩石和束缚水膨胀以及应力敏感导致含气孔隙体积损失较小,是非主控因素。利用建立的库容参数模型,优化得到32 MPa上限运行压力条件下,最大工作气量为25.61×10⁸m³,对应最优下限运行压力为18 MPa,库容量为64.74×10⁸m³。研究成果可为国内外同类低渗透底水火山岩气藏改建储气库提供借鉴。

Quantitative Evaluation of Main Controlling Factors of Capacity and Working Gas Volume Pf Volcanic Gas Storage With Bottom Water

In view of the special geological conditions of the Shengping gas storage that was reconstructed from a volcanic gas reservoir with bottom water, the effective gas-bearing pore volume was calculated by the gas saturation respectively of pure gas zone, transition zone and water flooded zone, a three-zone storage capacity parameter model of gas storage was established under consideration of effect of water invasion, stress sensitivity, rock and bound water deformation, a calculation method was optimized and designed to iteratively calculate the maximum working gas volume and the relevant storage capacity in different operating pressure intervals, and a quantitative evaluation was conducted on the effect of water invasion, stress sensitivity, rock and bound water deformation and other factors on the storage capacity and working gas volume. The results showed that the loss of gas-bearing pore volume was the largest in the transition zone, followed by the pure gas zone and then the water flooded zone; in terms of the loss of gas-bearing pore volume by different factors, water invasion was the dominant controlling factor, and rock and bound water expansion and stress sensitivity were non-dominant controlling factor and resulted in less loss of gas-bearing pore volume. With the established storage capacity parameter model, the maximum working gas volume was 25.61×10⁸m³ under the upper operating pressure limit of 32 MPa, and the storage capacity is 64.74×10⁸m³ corresponding to the optimal lower operation pressure limit of 18 MPa. The study results can provide reference for the reconstruction of gas storage in similar volcanic gas reservoirs with low permeability and bottom water at home and abroad.