Abstract: Sweet spot prediction is a key and difficult area for deep coalbed methane (CBM) exploration and development, which will restrict whether the large-scale efficient development of deep CBM can be achieved. The conventional sweet spot prediction method is to study the geological or engineering sweet spots separately. The sweet spot prediction/evaluation system based on the geology and engineering integration concept needs to be established urgently. The urgent task is to find an effective theoretical method for realizing the organic unity of geological and engineering sweet spots of deep CBM. The rock mechanical stratigraphy has the inherent attributes and innate advantages of connecting the geology and reservoir engineering of CBM, which provides a new method for overcoming the technical difficulties in the integrated prediction of deep CBM sweet spots. By summarizing the development characteristics of the geological and engineering sweet spots of deep CBM and the difficulties and challenges faced in sweet spot prediction, this paper discussed and analyzed the methodology of rock mechanical stratigraphy for the integrated prediction of deep CBM sweet spots, and carried out the application research of deep CBM sweet spot prediction based on rock mechanical stratigraphy. The research results show that the development law of natural fractures in deep coal reservoirs under the control of rock mechanical stratigraphy is a key constraint for predicting the geological sweet spots of deep CBM, while the development law of fracturing induced fractures under the control of rock mechanical stratigraphy, physical changes in reservoir rocks, and reservoir stimulation are the key factors for evaluating the deep CBM engineering sweet spots. With rock mechanical stratigraphy as a method mechanism, it is possible to realize the organic connection between sedimentary diagenesis, rock mechanical characteristics, geological structure and geostress field characteristics, geological accumulation response, reservoir engineering response, and integrated prediction of deep CBM sweet spots. The application and practice of rock mechanical stratigraphy in the fracture characteristic analysis and high permeability zone prediction of coal reservoir, coal-rock fracture behavior analysis and production zone selection, and fracturing and drainage optimization of CBM reservoir have preliminarily proved that it will be expected to be a technical tool to solve difficulties in the integrated prediction of deep CBM sweet spots.

Key words: deep coalbed methane, exploration and development, sweet spot prediction, rock mechanical stratigraphy, fracture

摘要： “甜点”预测是深部煤层气勘探开发的重点和难点领域，制约深部煤层气能否实现规模效益开发。传统"甜点"预测方法是将地质"甜点"或工程"甜点"单独研究，基于地质—工程一体化理念的"甜点"预测/评价体系亟待建立，当务之急是找到有效的理论方法去实现深部煤层气地质"甜点"与工程"甜点"的有机统一。岩石力学地层（学）具有衔接煤层气地质与储层工程的固有属性与先天优势，为攻克深部煤层气"甜点"一体化预测的技术难题提供了新方法。笔者梳理分析了深部煤层气地质"甜点"与工程"甜点"的发育特征及其预测面临的难题与挑战，讨论提出了深部煤层气"甜点"一体化预测的岩石力学地层方法，探索开展了基于岩石力学地层的深部煤层气"甜点"预测的应用研究。研究结果表明：岩石力学地层控制下的深部煤储层的天然裂隙发育规律是深部煤层气地质"甜点"预测的关键制约条件，而在岩石力学地层控制下的压裂诱导的裂缝发育规律、储层岩石物理变化与储层可改造性则是深部煤层气工程"甜点"评价的核心因素；以岩石力学地层为桥梁纽带和方法机制，可实现深部煤储层沉积成岩作用—岩石力学特征—地质构造与地应力场特征—地质成藏响应—储层工程响应—深部煤层气"甜点"一体化预测的有机衔接。岩石力学地层方法在煤储层裂隙发育特征分析与高渗区预测、煤岩破裂行为分析与产层优选、煤层气藏压裂与排采优化中得到了应用与实践，有望成为破解深部煤层气"甜点"一体化预测难题的技术利器。

关键词: 深部煤层气, 勘探开发, "甜点"预测, 岩石力学地层, 裂隙(缝)