用增长曲线一体化法预测水驱油田开发指标

A Method for Intergrative Prediction of Development Index of Waterflooding Reservoirs

罗　洪,俞启泰

Luo Hong , Yu Qitai

中国石油勘探开发科学研究院

Research Institute of Petroleum Exploration and Development , CNPC, Beijing 100083 , P. R. China

建立一种新的油藏工程方法———增长曲线法,在预测油田N_p - t 和Q_t - t 关系中已是一种相当成熟和成功的方法,但水驱油田的f _w - t 关系也是一个非常重要的开发指标。本文推导了利用3Y1 、3W和3Y2 增长曲线描述和预测f _w - t 关系的公式,并提出了用于求取其参数的过原点重复线性回归法。随机选取了低粘(地层原油粘度μ_o < 3 mPa·s) 的兴隆台油田、中粘(3 ≤μ^_o ≤30 mPa·s) 的双河油田和高粘(μ_o > 30mPa·s) 的孤东油田,用上述3 种增长曲线拟合这3 个油田实际的N_p - t 、Q_t - t 和f _w - t 数据,根据拟合相关系数的大小,筛选了用同一种增长曲线计算上述开发指标的结果。理论分析表明,3Y2 增长曲线在Q_t - N_p关系后期为向上凹的曲线,说明产量下降和含水上升均较慢,这符合高粘油田的水驱特征;而3Y1 增长曲线在Q_t - N_p 关系后期为向下凹的曲线,表明产量下降和含水上升均较快,这符合低粘油田的水驱特征;而中粘油田则介于两者之间。

The growth curve method , which is a new kind of reservoir engineering method , has already been a quite mature method for predicting relationships of cumulative production Np , vs time t , production Qt , vs t . But water cut f w vs t of the water flooding reservoirs also is a very important development index. In this paper , the formula for discribing and predicting the relationship of f w vs t have been derived by using 3Y1 , 3W and 3Y growth curves , and the repeated linear regression methods for obtaining the parameters of these growth curves have been proposed. Xinglongtai Oilfield with low formation oil viscosity (formation oil viscosity μ0 . < 3mPa•s) , Shuanghe Oilfield with middle formation oil viscosity (3 mPa•s ≤u0 ≤ 30 mPa•s) and Gudong Oilfield with high formation oil viscosity ( u0 > 30 mPa•s) were selected random , then the relationships of Np . vs t , Qt , vs t and f w vs t were fitted by actual data of these oilfields , and according to larger or smaller of the correlation coefficient , the growth curves applying to different kinds of oilfield were screened. The results screened are : the 3Y2 growth curve applies to high oil viscosity oilfields and the 3Y1 growth applies to middle and low oil viscosity oilfields , where as additional method to 3Y1 growth curve , 3W growth curve can apply to middle oil viscosity oilfields when cumulative production corresponding to peak production is greater than half maximum recoverable reserves. The theoritical analysis shows that : ①in the later section of relationship of Qt , vs Np , 3Y2 growth curve is a concave curve upward that indicates the rise of water cut and decline of production both are slower , it accords with water displacement characteristics of waterflooding reservoirs with high formation oil viscosity ; ② in the later section of relationship of Qt vs Np , 3Y1 growth curve is a concave curve downward that indicates that rise of water cut and decling of production both are faster , is accords with water displacement characteristics of waterflooding reservoirs with low formation oil viscosity ; ③but the waterflooding reservoirs with middle formationoil viscosity are between them. So screened result s mentioned above show that the proposed methods for integrative prediction of development indexes of waterflooding reservoirs by using the growth curves are correct and applicable.