Research Of Large Gas Field Investment Evaluation System And Empirical Test

Natural gas, as one of the world’s three major traditional energy, has become a high-concerned energy force because of a series of advantages such as its stable output, high global reserves and constant mining cost. But the development of gas field needs single large funds investment and intensive technology, and accompanied by high level of risk, so the rationality of gas field plan is the guarantee of ultimate economic benefits of a gas field development, in which the economic evaluation of gas field development can improve the technical level, reduce the risk of investment and improve the benefit rate of investment. The economic evaluation of gas field development and investment plays an essential role in large gas field developing project, and it also undertakes specific responsibility of the social development.We have compared the economic evaluation system of the development of gas fields at home and abroad, and analyzed the current evaluation system of gas field development project in China including the main method and reference indicators. We found that there are many imperfections, such as most economic evaluation have only considered a simple economic evaluation method, and to determine the parameters after investment budget and project development, without the implementation of financial evaluation, economic feasibility analysis and project risk calculation. After studying the related theories of gas field economic evaluation system, we improved the economic evaluation system in the guidance of the system view and the view of harmonious development, including assessment methods and parameters selection, project investment budget, economic benefits analysis (profitability and risk control) and the analysis of social economy and ecological environment benefits. This article focuses on the part of using the modern cost estimation method, the uncertainty and risk assessment in economic analysis, as well as the social and environmental benefits of the evaluation system and constructing the harmonious development index of the natural gas energy, the society and the environment system.The main innovations and discoveries in this paper are as follows:(1) Under the guidance of systematic theory and coordinated development theory, this research build a framework based on the comprehensive evaluation system as the main means of coordination. With the concept of sustainable coordinated development we reveal the contradiction between energy consumption and economic development. In a macro point of view, we explored the mechanism of economic evaluation system in the process of gas field development, and made the theoretical foundation for the economic evaluation system of gas field development project.(2) The principle and method of system level analysis is introduced into the research of gas field development evaluation system. Through the research of advanced international oil gas field development evaluation and comparison of existing experience in China, we regulate the economic evaluation of gas field development and improvement of the existing framework. The improved theoretical framework of gas field development evaluation includes the analysis of risk prevention and environmental effects. It has four levels:the project economic evaluation method and parameters; estimation of project investment; economic benefits analysis including profitability and risk control; the analysis of social economy and ecological environment benefits.(3) Based on perfecting the evaluation framework, we made a deep study on the key technical improvement project, including the introduction of modern cost management method to estimate the cost, the introduction of uncertainty and risk analysis to full the traditional pure profit and benefit analysis on consideration of social coordination of economic and environmental sustainable development.(4) The studies on the sedimentary facies, sedimentary subfacies, sedimentary micro-facies and the depositional evolution sequence of the main reservoir of Sulige gas field were carried out. According to the dividing indexes of the sedimentary facies, the sedimentary micro-facies of Sulige gas field were identified. The result suggest that the reservoirs from Shan 1 formation to He 8 formation in the study area were braided-river～delta that deposited in a moisture swamp environment, which had a certain distance to the provenance. The sedimentary subfacies of the reservoirs from Shan 1 formation to He 8 formation in the study area can be divided into the following four kinds of sedimentary micro-facies:the braided river, the channel-filling (distributary channel), the flood plain, and inter-channel depressions(5) The study of the characteristics of the reservoir of the Sulige gas field contained the reservoir petrology, physical properties and characteristics of pore structure and other aspects. The result shows that the physical properties of the reservoirs of Shan 1 formation and He 8 formation are quite different.(6) The production scale and productivity are based on the certain gas production plant in Sulige gas field. Based on the analyzing of the law of the natural decline of the annual production, three exploitation plans were as follows:the first plan is an eight-year stable production period and a seven-year decline production period; the second one is a ten-year stable production period and a six-year decline production period; the last plan is a twelve-year stable production period and a five-year decline production period.(7) According to the characteristics of gas field, we use the modern cost management method to estimate the project cost, including the operating cost method, data envelopment analysis and BP neural network method etc.. We also made empirical research of cost estimating of "Sulige" gas field, and prove that the modern cost management methods will make the evaluation result more reasonable, and it can further improve the credibility of subsequent economic evaluation results.(8) In the benefit analysis, we use the uncertainty and risk analysis plan which based on traditional pure profit and benefit analysis. In order to make the evaluation results can be used by decision makers, this paper introduces the "probability tree" and Monte Carlo simulation method, the Monte Carlo econometric model regression is using historical data, so as to simulate the distribution of all the possible future, using probability theory to calculate uncertain results of the expected future. This paper makes an empirical study on a gas field in "Sulige", using the improved method to evaluate the possible mining plan, and comes up with the evaluation results and related suggestions.(9) The improved economic evaluation system has introduced the analysis of social socia economy and ecological environment benefits. In this paper, through constructing the coordinated development evaluation system of natural gas energy, social economy and ecological environment, and then build the evaluating index system of social economy and ecological benefits to evaluate the large-scale investment in gas field development. We also made empirical research of ecological environment of "Sulige"gas field.