水驱油田的驱替特征与递减特征

DRIVE CURVES AND DECLINE CURVES FOR WATER DRIVE FIELD

推导了Ａｒｐｓ递减指数ｎ＝０，即指数递减对应的水驱特征曲线表达式。与ｎ＝０．５和１．０的递减曲线，即ｎ＝０．５的双曲递减和调和递减对应的水驱特征曲线一起，首次建立了完整的递减曲线与水驱曲线的联系。利用含水率（ｆｗ）～可采储量采出程度（Ｒ）关系图上的递减指数ｎ＝０、０．５、１．０的理论曲线，研究了水驱油田的驱替特征与递减特征。研究表明，我国绝大多数层状油田的ｆｗ～Ｒ关系在ｎ＝０到１．０的理论曲线范围内；底水驱灰岩油田有不同于层状油田的特别的ｆｗ～Ｒ关系；油田开采方式决定了ｆｗ～Ｒ变化的大的趋势；油水粘度比和油层非均质性对ｆｗ～Ｒ关系有很大影响，油水粘度比越大，油层非均质性越强，则ｆｗ～Ｒ曲线越凸。油田开发后期，实际油田的ｆｗ～Ｒ关系均趋向于ｎ＝０．５的曲线。

In this paper, the expression function of water drive curve corresponded to the Arps'decline exponent n =0, i. e. exponential decline was derived. Considering the expression mentioned above, together with other water drive curve expressions corresponded to the Arps' decline exponent n =0. 5 and 1. 0 (i. e. the hyperbolic decline of n =0. 5 and the harmonic decline of n=1. 0), the relationship between the decline curves and the water drive curves was established completely. on the basis of the typical curves of n=0, 0. 5 and 1. 0 on the plot of water cut fw vs. recoverable reserve recovery R., the drive curves and decline curves for the water drive fields were studied. The results indicated that:(1)The fw vs. R relations for most layer fields in China varied within the range of theoretical curves of n=0and 1.0.(2)The fw vs. R relationship of the bottom-water drive limestone reservoirs differ from layer reservoirs stated above.(3)The general trend of the fw vs. R variations were controlled by the development scheme of a field. (4) The fw vs. R relations are also influenced significantly by the oil-water viscosity ratio and the heterogeneity of the reservoirs, i. e., the higher the oil-water viscosity ratio, and/or the stronger the heterogeneity of the reservoirs, the larger the convexity of the fw vs. R curves. Nevertheless, the actual fw vs. R relations of the oil fields at later development stage are all tending towards the curve of n=0. 5.