水驱油田产量递减规律

DECLINE CURVE ANALYSIS FOR A WATER DRIVE RESERVOIR

根据表示不同含水上升规律的水驱特征曲线公式,推导了在定产液量条件下的水驱油田的产量递减曲线公式,从而首次建立了水驱特征曲线与递减曲线的联系。推导的4种水驱油田递减公式中,有两种与油田含水率无关,并符合 Arps 递减(Arps 双曲递减指数分别为0.5和1.0);有两种与油田含水率有关,但不符合 Arps 递减。在广义递减曲线(Arps 双曲递减)标准图版上画出的水驱油田递减曲线表明,在低含水阶段(含水率=0.2),其双曲递减指数(n)范围为—4.0～1.0;在高含水阶段(含水率=0.9),n 的范围为—0.2～1.0。推荐了一个适用各种原油粘度,在高含水阶段的水驱油田的水驱特征曲线公式及相应的递减曲线公式。这个递减曲线相当于 Arps 双曲递减指数 n=0.5的情况。这一递减曲线公式正确地反映了水驱油田的递减规律,有使用方便、计算结果准确的特点。

In term of the waterdrive characteristic curve formulae which indicate the different regu- larities of water cut change,at a fixed withdrawal rate in the waterdrive reservoir the decline curve formulae are derived.Thus an association between the waterdrive characteristic curve and the decline curve is established for the first time.In four waterdrive curve formulae de- rived,two of them bear no relation to water cut and conform with the Arps'decline curve corresponding to Arps'decline indices of 0.5 and 1.0,respectively,others two bear some rela- tion to water cut and do not conform accord with the Arps'decline curve.The decline curves for a waterdrive reservoir plotted in the generalized decline type curve(the Arps'hyperbolic curve)show that these decline curves change between-4.0 and 1.0 for the Arps' hyperbolic curve in the low water cut stage(water cut=0.2),but for these decline curves a change be- tween-0.2 and 1.0 for the Arps' hyperbolic curve in the high water cut stage(water cut= 0.9)occur.Waterdrive curve formula and corresponding decline curve formula which apply to the waterdrive reservoir having different oil viscosity in the high water cut stage is recom- mended.This decline curve correspond to the Arps' decline curve when decline index is equal to 0.5.This decline curve correctly reflects decline of a water drive reservoir and its feature is to be used easily.