基于流固耦合的变质岩潜山裂缝型凝析气藏数值模拟研究

BZ气田为渤海最大的变质岩潜山凝析气田，具有储渗类型多样、特高含凝析油、应力敏感性强的特点，目前尚无类似开发实例。通过网格之间流体渗流的等效方式建立砂砾岩、半风化带、潜山内幕三类复杂储层并存的油藏模型，利用应力敏感实验获得BZ气田渗透率残余系数表达式，结合反凝析特征规律开展流体渗流-多孔介质变形动态耦合及评价。研究表明：多渗流系统精细表征及耦合是精细油藏数值模拟基础，流固耦合效应是影响开发效果影响的关键；考虑BZ气田裂缝发育，构造高部位注气易形成气顶驱，扩大波及体积；考虑反凝析特征，保持地层压力高于露点压力能最大限度降低凝析油的损失；按冬季供气需求阶段性循环注气有利于形成压力脉冲，扩大波及体积，提高凝析油采收率。研究成果对类似复杂裂缝性凝析气藏开发具有重要的指导意义。

Numerical Simulation of Metamorphis Buried-Hill Fractured Condensate Gas Reservoir Based on fluid-sloid Coupling

The BZ gasfield is considered as the largest metamorphic buried-hill condensate gasfield in the Bohai Oilfield,which is featured by multiple reservoir-permeability categories,extra-high condensate oil content and stong stress-sensitivity.There is no similar development case at present.The equivalent treatment of inter-grid fluid seepage was adopted to establish a reservoir model with multiple reservoir categories,including glutenite,semi-weathered zone and inner buried-hill.The expression of residual gas reservoir permeability in the BZ gasfield was derived by the laboratory stress-sensitivity test.The dynamic coupling and evaluation between fluid seepage and porous media deformation were conducted through reverse retrograde condensation patterns.Research indicates that fine characterization and coupling of multiple seepage systems are the basis for fine reservoir numerical simulation,and the fluid-solid coupling performance is the dominant aspect for development performance.Considering the well-developed fractures in the BZ gasfield,gas-cap driving can be realized by high-part gas injection to expand swept volume.In veiew of the retrograde condensation,the condensate oil loss can be minimized through keeping the formation pressure above dew-point pressure.Cyclic gas injection in accordance with winter gas supply is favorable to create formation pressure pulses,expand swept volume and enhance condensate oil recovery.This research could provide certain guidance for the development of similar complex fractured condensate gas reservoirs.