| Daniudi gas field is a large lithological reservoir of sandstone, with sandwich structure, which is tight with low permeability. The gas field is characterized by abundant in reserve, seven gas-bearing beds, strong inhomogeneity of reservoir, and low pressure, low permeability, low production. The sedimentary facies of the gas reservoir is mainly fluvial facies. The thickness of reservoir varies on longitudinal and fraverse. The pressure coefficient is 0.89-0.98. The permeability of reservoir is less than 1 md. The well production rate is also low, about 0.5～2x 104m3/per day. So that, it's difficult to exploit. The gas field has produced since 2005. Until late in 2008, its production capacity is up to 23 x 108 m3/per year sum as yield. The air demand of it accounts for 58.23%of whole north china. With the construction of Yuji pipeline, the importance of stable gas supply supporting of Daniudi gas field is obvious increasingly. According to the development plan in 2005, the maturing gas field will soon enter the period of depletion, and the decreasing rate of production capacity may be 1 x 108 m3/per year. Therefore, it's urgent to study the stable producing strategy of the maturing areas of Daniudi gas field in the middle and late period.Begin with the basic geological characteristic of the gas field, the thesis have achieved the new recognition of this gas field, using description technique for gas field, dynamic analysis, simulation experiment in lab and numerical modeling. The main content of the thesis include four aspects as follow. Firstly, the distribution of physical property and the inhomogeneity characteristic was determined by dividing flow units of the reservoir and fine modeling of gas field. Secondly, we have studied the development feature. The present situation of development the gas field and the law of production was learned, by analysis of single-well production characteristic, the law of loading and unloading, and the evolution of production and service pressure of the gas field. Thirdly, the recovery efficiency and the timing of commingling production ascertained, through the simulating experiment of single drill core and long drill core combination in parallel. Finally, the regularities of distribution of the residual gas in the gas field were determined, using the numerical modeling. Base on understanding the law of the gas field and integrating the development geology, dynamic characteristics of gas, simulation of gas production, reservoir modeling and Numerical simulation of gas, we evaluated objectively the potentiality of it, and proposed multi-layer composite for low permeability tight sandstone gas reservoirs in various stages of development of the three stable production technology. These are bowl perfect network technology, gas technology and gas reservoir pressurization commingled stable technology. By predicting the three stable yields strategy can increase production more than 1.86×108m3 per year. This strategy will prolong about 3 years of stabilized production period, so that there will be a huge economic efficiency and social benefit.The thesis is innovative, for example determining the critical liquid carrying flow rate of the gas reservoir, the timing of commingling production, and numerical modeling of the gas reservoir in consideration of permeability distribution model of artificial pressure-break, flow units, and stress sensitivity. At last, the technology of stable yields is established, which is adapt for the low pressure and tight gas reservoir in Daniudi gas field. It supports technical assurance for the development of the gas field in the middle and late period. Meanwhile, it has provided technological guidance and useful lesson for the other tight gas reservoirs with low pressure and tight in our country. |
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