裂缝性底水凝析气藏水侵机理研究

Because of the unclearly understanding on the water invasion mechanism of fractured gas condensate reservoirs with bottom water, the energy of bottom water is difficult to be used and controlled effectively, which leads to poor development effect at this kind of gas condensate reservoir. Aiming at the unclearly understanding on the water invasion mechanism on fractured gas condensate reservoirs with bottom water, a typical fractured gas condensate reservoir with bottom water has been chosen. Combined the microscopic research with macroscopic research, the physical modelling with mathematical simulation, the experiment study with theoretical study, using the theories of fluid mechanics in porous medium, gas reservoir engineering, gas reservoir numerical simulation and seepage experiment, a suit of comprehensive method appraising the size of energy of fractured gas condensate reservoirs with bottom water has been established. Based on the study of water lock experiment considering the influence of retrograde condensation, long core displacement experiment, relative permeability experiment of water-drive gas and gas-drive water, the influence of a variety of geological and development factors on water invasion would be researched, and the water invasion mechanism also would be revealed. At the same time, using the mathematical theory of vague mathematics , the main geological and development factors which influence water invasion mechanism would be chosen, and the model of calculating water influx, water influx warning equation and the oil-gas-water three phase numerical models on fractured gas condensate reservoirs with bottom water also would be established, which can explain the water invasion rule of fractured gas condensate reservoirs with bottom water. The key base would be built for developing the fractured gas condensate reservoirs with bottom water scientifically and rationally by this paper.

因对裂缝性底水凝析气藏水侵机理认识不清，气藏开发过程中难以有效利用和控制底水的能量，导致该类气藏总体开发效果较差。本研究针对目前对裂缝性底水凝析气藏水侵机理认识不清的问题，选取典型裂缝性底水凝析气藏作为研究对象，采用微观和宏观研究相结合、物理模拟和数学模拟相结合、实验研究和理论研究相结合的研究思路，综合运用渗流力学、气藏工程、气藏数值模拟及渗流物理实验等多学科理论，建立一套在气藏开发早期准确评价底水能量大小的综合方法；在考虑反凝析影响的水锁实验、长岩心驱替实验、水驱气和气驱水相渗实验研究基础上，研究多种地质和开发因素对气藏水侵的影响，揭示底水的水侵机理。应用模糊数学基本理论遴选出影响水侵的主要地质及开发因素，建立水侵量计算模型、水侵预警方程和裂缝性底水凝析气藏油气水三相渗流数学模型，弄清裂缝性底水凝析气藏的水侵规律。本研究可为科学合理开发裂缝性底水凝析气藏奠定关键科学理论基础。

针对裂缝性底水凝析气藏水侵机理认识不清的问题，选取典型裂缝性底水凝析气藏作为研究对象，采用微观和宏观研究相结合、物理模拟和数学模拟相结合、实验研究和理论研究相结合的研究思路，综合运用渗流力学、气藏工程、气藏数值模拟及渗流物理实验等多学科理论对裂缝性底水凝析气藏水侵机理进行研究，取得了以下成果：. （1）开展了考虑反凝析影响的水锁实验、长岩心驱替实验、水驱气和气驱水相渗实验，研究了裂缝性底水凝析气藏反凝析污染以及水侵因素对地层的伤害和对产能的影响。结果表明水锁和油锁启动压力梯度与渗透率的变化基本满足线性关系，随渗透率的增加而降低；由于流体与流体间的界面张力差异，油锁的启动压力梯度比水锁略小。. （2）基于罐状水层模型和Fetkovich方法，结合有水凝析气藏的物质平衡方程，建立了一套在气藏开发早期准确评价底水能量大小的综合方法；在考虑反凝析影响的水锁实验、长岩心驱替实验、水驱气和气驱水相渗实验研究基础上，结合地质建模和数值模拟技术，研究了多种地质和开发因素对气藏水侵的影响，采用正交试验设计的方法，应用模糊数学理论遴选出气井距底水距离、水体能量、垂向裂缝发育程度、水平渗透率、气井产量、近井地带凝析油饱和度、气层厚度等影响水侵的关键因素，揭示了底水的水侵机理；建立了裂缝性底水凝析气藏水侵量计算模型、水侵预警方程，可预测水侵动态，实现水侵气藏的早预警、早调整。. （3）在裂缝性底水凝析气藏水侵实验研究基础上，综合考虑基质和裂缝系统中气、水、凝析油三相流动，基质和裂缝系统之间的流体交换，衰竭式开发过程中的反凝析及水侵现象，建立了裂缝性底水凝析气藏双重介质组分数学模型，应用数值模拟技术对典型裂缝性底水凝析气藏的水侵规律进行研究，验证了模型的可靠性，提出了有效防水和控水、合理利用水体能量的技术措施。. 本研究为科学合理开发裂缝性底水凝析气藏，提高经济效益奠定关键科学理论和技术基础，具有重要的科学意义和工程实用价值。