非均质碳酸盐岩油气藏酸压数值模拟研究进展与展望

要实现深层、超深层海相碳酸盐岩油气藏的高效开发,亟需相关酸化压裂技术理论的突破与创新。为了指导多种酸压工艺的现场实践,通过系统梳理和总结酸压数值模拟技术的已有研究成果,结合目前深层、超深层海相碳酸盐岩油气藏酸压工程的技术需求,探索研究了当前酸压数值模拟面临的新挑战和需要突破的方向。研究结果表明:①酸压三维数值模拟基于解耦思想,将酸压模型分为水力裂缝初始形态构建、酸刻蚀模拟及导流能力计算等3个模块,其中酸刻蚀模拟模块是酸压数值模拟的核心;②地质统计学参数方法在水力裂缝初始形态建模中的应用已较为成熟,酸刻蚀模拟通过N-S方程组、酸平衡方程、酸液滤失模型及酸岩反应溶蚀力方程耦合求解,已初步实现了精细化和油藏工程尺度的模拟,酸蚀裂缝导流能力的计算主要基于局部立方定律进行求解,并考虑了多重因素对导流能力的影响。结论认为,酸压数值模拟面临的新挑战包括酸液在复杂流动介质中的多场耦合高效计算、酸刻蚀过程的精细模拟、酸蚀裂缝导流能力的准确计算以及酸压数值模拟与酸压工程应用的匹配;需要突破的方向是实现多场、多尺度的酸压数值模拟。

Research progress and prospect of numerical modeling for acid fracturing of heterogeneous carbonate reservoirs

It is urgent to make breakthroughs and innovations in relevant technical theories of acid fracturing in order to realize the high-efficient development of deep and ultra-deep marine carbonate reservoirs. In order to guide the field practice of various acid fracturing processes, the new challenges facing the current acid fracturing numerical simulation and problems needed to break through were studied by systematically reviewing and summarizing the existing research results of numerical simulation technology of acid fracturing, based on the current technical requirements of acid fracturing engineering for deep and ultra-deep marine carbonate reservoirs. The results show that: (1) based on the idea of decoupling, the three-dimensional numerical model of acid fracturing is divided into three modules: construction module of initial form of hydraulic fractures, simulation module of acid etching, and conductivity calculation module, among which the simulation module of acid etching is the core for numerical simulation of acid fracturing; (2) the application of geostatistics parameter method in the modeling of initial form of hydraulic fractures has been mature. The coupled solution of acid etching simulation is conducted through N–S equations, acid balance equation, leak-off model of acid fluid and acidic rock reaction dissolution equation. The refined simulation at reservoir engineering scale has been preliminarily realized. The calculation of conductivity of acid etching fractures is mainly based on the local cubic law in consideration of the influence of multiple factors on conductivity. In conclusion, the new challenges facing numerical simulation of acid fracturing include the high-efficient calculation of multi-field coupling of acid liquid in complex flowing media, the fine simulation of acid etching process, the accurate calculation of conductivity of acid etching fractures, and the matching of acid fracturing numerical simulation with acid fracturing engineering application. The direction to break through is to realize the multi-field and multi-scale numerical simulation of acid fracturing.