考虑吸附影响的凝析气井压力降落试井分析

凝析气井的试井解释,基本上仍沿用干气井的单相拟压力方法,或在解释中根本就没有考虑多孔介质对凝析油、气的吸附影响。大量实验与理论研究表明,多孔介质吸附对凝析油、气的渗流具有较大的影响,在考虑吸附影响的凝析气井渗流微分方程的基础上,建立了不稳定试井解释数学模型,将多孔介质吸附影响直接纳入了模型之中。提出了多种外边界条件下的压力降落试井分析方法。实例分析表明,与不考虑多孔介质吸附影响的情况相比,因多孔介质吸附的影响,试井解释有效渗透率将降低,表皮系数增大,气井有效泄流半径与单井控制储量亦将降低。对于重烃含量较高和孔隙度较低的凝析气藏,多孔介质吸附的影响将更加明显。研究表明,多孔介质界面现象对凝析气井的渗流特征与试井解释的影响不应忽视。

DRAW DOWN WELL TEST ANALYSIS OF GAS-CONDENSATE WELL CONSIDERING THE INFLUENCE OF ADSORPTION

For well-test of condensate-gas well, the method of dry-gas well’s single phase pseudo-pressure is continued to use usually. Or the influence of porous media adsorption of condensate-gas and oil is not considered in the procedure of analysis. But many experiments and theoretical studies indicate that porous media adsorption has great influence on the percolation of condensate gas and oil. A mathematical model of transient well-test analysis is developed in this paper on the basis of differential equations of percolation of condensate gas and oil which considered the influence of adsorption. The influence of porous media adsorption is taken into account directly in the model. Approaches of draw down test interpretation are given in multiple outer boundary conditions. The effective permeability of well test analysis will decrease, skin factor will increase, effective leakage radius and controllable reserves of well will decrease too on the condition of reservoir as against the condition of not considering porous media adsorption. These are verified by example studies. For those gas-condensate reservoirs, which heavy hydrocarbon contents are higher and porosities are lower, the influence of porous media adsorption would be more apparent. The researches of this paper indicate that porous media interfacial phenomena have great influence on the laws of gas-condensate reservoirs’ percolation and well-test analysis. The influence can’t be neglected.