Technical-economic Evaluation Of Natural Gas Development In Volcanic Reservoirs In Xingcheng Gas Field Of Songliao Basin

Along with the technology improvement of the oil and gas exploration and development, a large-scale of natural gas in the deep-seated volcanic reservoir has been found in the northern part of Songliao Basin in China. It is estimated that the reserve could reach 300 to 500 billion cubic meters. However, deep natural gas exploration and development in China is still in its infancy. As the strategy of protecting environment, optimizing the energy structure and promoting the sustainable development in China has been implemented, government and business decision-makers at all levels will increasingly pay attention to the technical and economic evaluation on deep-seated gas development. The technical and economic evaluation on deep-seated gas exploration and the according risk decision making is a complex and systemic research. According to the volcanic reservoir gas characteristics including various lava types, complex lithology, quick changes of lithofacies, micro-fracture of the reservoir, poor physical properties, strong heterogeneity and tough development, the thesis standardizes the technical and economic evaluation procedures of the development, and uses a multidisciplinary approach to systematically and comprehensively study and evaluate the deep-seated volcanic reservoir gas development program.There might be the phenomenon of water wells during the process of natural gas exploitation, especially in Xingcheng Volcanic reservoir in Songliao Basin Gas Field, which makes the gas wells have gradually lost their self-spraying ability and seriously affects the recovery and the production capacity. In view of this situation, the thesis establishes an index system for gas drainage technology options from technical and economic perspectives. It adopts improved interval data envelopment analysis to evaluate and optimize its technology. The efficiency index of the improved model can be greater than 1, which reduces the mutual overlap of the interval efficiency indices and lays the foundation for the better choice of the deep-seated gas drainage technology. At the same time, through the projection analysis, it points out the inadequacies of the non-effective gas drainage technology, as well as the range of improvements, which provide a reliable basis for the deep-seated volcanic reservoir gas development program.According to the actual situation of the optimum gas drainage technology, the paper sums up the technical and economic characteristics of the deep-seated gas development program, and puts forward the key points in the choice of development methods, development layer division and the development pattern determination based on the principles and procedures designed in the program. Then it adopts the improved TOPSIS method to optimize the development program.In order to reduce the risks of the program, the paper uses probability analysis method to analyze the risks of the optimized one. Based on the determination of the risk rate of compensation, it establishes a new evaluation model, which evaluates the program and provides a scientific basis for decision-making. At the same time, it illustrates the risk sources from the perspectives of uncertain resources evaluation results, uncertain development evaluation results, uncertain project evaluation results and uncertain economy evaluation results, and also proposes the corresponding preventive measures.