超深缝洞型碳酸盐岩储层埋藏深,压力高,储集空间复杂多样,流体流动渗流、自由流并存,储层连通性表征困难,而储层连通性的精确表征是寻找油气富集区、储量精确预测、井网优化和井位部署的关键所在。为此,以塔里木盆地富满油田超深缝洞型碳酸盐岩储层为研究对象,考虑流固耦合作用,建立缝洞型储层应力-渗流-自由流耦合数学模型,采用岩石渗透率演化试验和数值模拟相结合的方法,系统开展了超深缝洞型碳酸盐岩储层连通性研究。研究结果表明:随着围压、轴压的增加,岩石渗透率逐渐降低,岩石连通性减弱;低围压条件下,轴压对岩石渗透能力和连通性影响显著;随着裂缝开度和倾角的增加,储层连通性逐渐增强;裂缝连通溶洞能够显著改善储层连通性;随着溶洞体积的增加,流体流速与等效渗透率增大,显著改善储层连通性;而单纯增加溶洞数量,会减弱自由流(Stokes)效应,改善储层连通性效果不明显。研究成果可为深层碳酸盐岩储层精确评价,提高油气高效勘探开发效果提供技术支撑。

Ultra-deep fractured-cave carbonate reservoirs are buried at great depths, with high stresses, and possess complex and diverse storage spaces. Fluid flow and seepage coexist, making the characterization of reservoir connectivity challenging. Accurate characterization of reservoir connectivity is crucial for identifying oil and gas enrichment areas, predicting reserves precisely, optimizing well patterns, and planning well locations. Therefore, this study focuses on the ultra-deep fractured-cave carbonate reservoirs in the Fuman Oil Field of the Tarim Basin. Considering the effect of fluid-solid coupling, a coupled mathematical model of stress seepage and free flow in fractured-cave reservoirs was established. A systematic study on the connectivity of ultra-deep fractured-cave carbonate reservoirs was conducted using a combination of rock permeability evolution experiments and numerical simulations. The research results indicate that with the increase of confining stress and axial stress, rock permeability gradually decreases, leading to weakened rock connectivity. Under low confining stress conditions, axial stress significantly affects rock permeability and connectivity. As the fracture aperture and angle increase, reservoir connectivity gradually improves. Fracture-connected caves can significantly enhance reservoir connectivity. The fluid flow rate and equivalent permeability increase with the increase in cave volume, which greatly improves reservoir connectivity. However, simply increasing the number of caves weakens the free flow (Stokes) effect, resulting in a less significant improvement in reservoir connectivity. The research findings provide technical support for the precise evaluation of deep carbonate reservoirs and enhance the efficiency of oil and gas exploration and development.