Frontier research of geological technology for coal measure gas joint-mining

Coal measure gas( CMG) exists in different lithologic reservoirs with different phases,and its exploration and development effect depends on the compatibility and its geological controls of the adsorbed and free gases or the organic reservoir and inorganic reservoir gases joint-mining. Thus,the geological technology of joint-mining is one of the key factor in CMG development technology system. It has been realized that the contradiction between joint gas- producing layers is just the compatibility of joint CMG production. The compatibility,originated from the differences of the reservoir energy and properties between the joint-producing layers,can be identified with the methods such as sta- tistical data analysis,numerical simulation and physical simulation,but there is a difference in the understandings of geological controls. A variety of the identification means for the gas-producing contribution from the joint-mining layers have been tried and developed,such as the gas-production curve identification,numerical and physical simulations,re- al-time monitoring and the produced-water geochemical dynamics. These methods have their own characteristics. What is worth paying attention to is the whole process inversion based on the peak splitting method of gas production curves. It is recognized that the threshold of joint gas production is impossible to be avoided. The methods of the Joint CMG- producing layers optimization and the sweet area prediction have been established by taking the gas-produced contribu- tion as an objective function,and applied in the engineering demonstration preliminarily. These advances indicate that the geological evaluation technology system of CMG is being formed,and the technological connotation is being en- riched and deepened. It will play an important role in the large-scale development of CMG in China.