遗传算法在水驱气藏地质储量及水侵量计算的应用

对于水驱气藏,特别是比较活跃的水驱气藏。水侵主要维持地层压力,并将产量维持在初始产量,直到水锥突破,其结果直接影响到气藏的采收率,因此如何准确计算水驱气藏地质储量和水侵量大小,对气藏动态预测显得非常重要。国内外学者曾作过大量的研究,但由于过分理想化的假设,使计算过程繁琐且结果精度不高。本文以物质平衡方程为基础,建立了关于地质储量和非稳态水侵量的非线性模型,并采用遗传算法进行求解,可以直接计算水驱气藏的地质储量及水侵量。通过实例对比分析,证明此方法具有计算过程简单、快速,计算结果准确、实用的特点。

AN OPTIMUM METHOD FOR ESTIMATING GEOLOGICAL RESERVES AND WATER INVASION RATE OF WATER DRIVE GASS RESERVOIRS

In respect of water drive gas reservoirs, in particular the active ones, the water influx helps to maintain the reservoir pressure, and thus maintain gas productivity at initial productivity, at least until water breakthrough. As a result, the process directly affects the recovery. Therefore, it is great importance to obtain accurate data of geological reserves and the water invasion rate so as to make correct performance forecast. The domestic and foreign scholars have done a great number of researches on this problem, however, their estimation results are always fussy and the precision in calculation is low because of the excessively idealized hypotheses. In this paper, a novel method is proposed. In the method a non-linear model of geological reserves and the unsteady state water invasion rate was established basing on the material balance equation, and the genetic algorithm is performed to obtain the results of geological reserves and water invasion rate of water drive gas reservoir directly. Comparative analyses of the results from this and other methods indicate that the proposed methods is simper and rapider to use as well as accurate and reliable.