Enhancing recovery and sensitivity studies in an unconventional tight gas condensate reservoir
即使采用多级水力压裂增产措施，致密气藏的采收率通常也低于15%。这种低采收率在致密凝析油气藏中更为严重，因为天然气衰竭开采会留下宝贵的凝析油。
本文研究了三种提高天然气采收率（EGR）的方法，包括采出气注入、CO2注入和注水，以提高加拿大Montney组致密凝析油气藏的油井产量。比较了三种EGR方法的开采效果，并评价了其经济可行性。对主要生产持续时间、井底压力和裂缝导流能力等关键因素进行了敏感性分析，并分析了它们对生产效果的影响。
结果表明，与简单衰竭开采法相比，随着流体的注入，累积天然气产量和凝析油产量均增加。与CO2注入相比，采出气回注得出更高的天然气和凝析油产量，而水驱则面临注入困难和相应的低波及效率。同时，由于现场可用的气源和最小的运输成本考虑，采出气回注的成本较低，比其他EGR方法获得更多的经济效益。
卡尔加里大学化学与石油工程系
Abstract
The recovery factor from tight gas reservoirs is typically less than 15%, even with multistage hydraulic fracturing stimulation. Such low recovery is exacerbated in tight gas condensate reservoirs, where the depletion of gas leaves the valuable condensate behind. In this paper, three enhanced gas recovery (EGR) methods including produced gas injection, CO2 injection and water injection are investigated to increase the well productivity for a tight gas condensate reservoir in the Montney Formation, Canada. The production performance of the three EGR methods is compared, and their economic feasibility is evaluated. Sensitivity analysis of the key factors such as primary production duration, bottom-hole pressures, and fracture conductivity is conducted and their effects on the well production performance are analyzed. Results show that, compared with the simple depletion method, both the cumulative gas and condensate production increase with fluids injected. Produced gas injection leads to both a higher gas and condensate production compared with those of the CO2 injection, while waterflooding suffers from injection difficulty and the corresponding low sweep efficiency. Meanwhile, the injection cost is lower for the produced gas injection due to the on-site available gas source and minimal transport costs, gaining more economic benefits than the other EGR methods.
Keywords： Tight gas condensate reservoirs Enhanced/improved gas recovery Produced gas injection Sensitivity study
