缝洞型碳酸盐岩双渗油气藏产量的变化规律

THE YIELD-CHANGE LAWS OF DUAL-PERMEABILITY OIL AND GAS RESERVOIRS OF FRACTURE-CAVITY TYPE IN CARBONATE FORMATIONS

我国缝洞型碳酸盐岩油气藏油气储量相当丰富,然而地质情况复杂、开采难度较大,深入研究该类油气藏渗流与流量动态规律对其高效开发油气藏十分重要。在研究地质模型的基础上,建立了三孔双渗油气藏产量变化的有效井径渗流模型,在Laplace空间对模型进行求解,并利用Stehfest数值反演绘制了产量递减曲线和累积产量曲线,详细讨论了窜流系数、储容比、表皮系数和外边界半径大小等参数对曲线的影响。分析表明,该类油气藏的产量递减曲线形态受封闭外边界半径大小以及窜流系数之间相对大小的影响很大,但在多数情况下仍表现出多孔介质油气藏产量递减曲线所具有的阶梯状性质。该产量递减规律为制定合理的生产制度提供了理论指导。

The reserves of fracture-cavity type carbonate oil and gas reservoirs are quite abundant. However, with the characteristics of complex geological situations and relatively great mining difficulty, it has considerable significance to further study on the reservoir seepage and flow dynamic laws, so as to develop such reservoirs with high efficiency. On the basis of study on the geological model, effective well diameter seepage model for the yield changes of three-hole dual-permeability gas reservoirs has been established; then this paper obtained the solution through the model in Laplace space, drew up the yield decline curve and the accumulation yield curve through Stehfest numerical inversion and discussed in detail the influences on the curve by the parameters, such as channeling flow coefficient, storage volume ratio, skin factors and the size of external boundary radius. The analysis shows that the form of reservoir's yield decline curve is deeply affected by the size of closed external boundary radius and the relative differences between channeling flow coefficients, but under most conditions, step-shaped property has been shown in the porous medium reservoir yield decline curve. The yield decline laws have provided theoretical guiding in making reasonable production projects.