基于物质平衡法确定超高压气藏动态储量的新方法

超高压气藏开发初期岩石压缩系数变化大，而目前超高压气藏物质平衡方程中却将岩石压缩系数取作常数，给动态储量计算带来了较大误差。利用超高压气藏岩石压缩系数的实验成果，建立了考虑压缩系数连续变化的超高压气藏物质平衡方程，并对方程进行线性化求解，提出了计算超高压气藏动态储量的新方法。应用结果表明：超高压气藏岩石压缩系数值对储量的计算结果影响非常大，对于四川盆地河坝超高压气藏，用岩石压缩系数取常数的物质平衡方法计算的储量值偏小13%~34%。因此，超高压气藏物质平衡方程必须考虑岩石压缩系数连续变化的特点，才能使动态储量计算结果更符合实际。

New material balance-based methods of determining the dynamic reserves of ultra-high pressure gas reservoirs

During the early stage of production in an ultra-high pressure gas reservoir, the rock compressibility shows a big change, but the present material balance equation for an ultra-high pressure gas reservoir regards the rock compressibility as a constant, which results in a big error in the calculation of dynamic reserves. Therefore, by use of experimental results of rock compressibility coefficient of an ultra-high pressure gas reservoir, a material balance equation was set up for this type gas reservoir with the consideration of the continuous variation in rock compressibility, and this equation was linearized to obtain the solution. Thus a new method of calculating the dynamic reserves of ultra-high gas reservoirs was put forward, and was compared with the conventional method using the rock compressibility as a constant. The application results from the Heba gas reservoir in the Sichuan Basin show that the rock compressibility coefficient of the ultra-high pressure gas reservoirs has a big effect on the calculation of reserves. It is suggested that for the ultra-high pressure gas reservoirs, experiments should be early carried out on the rock compressibility coefficient and petrophysical properties under high pressure before obtaining the related parameters of reserves calculation, thus its accuracy will be highly enhanced.