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2017, Vol.37 No.2  Publication date:20 April 2017
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  • A Forecasting Model  of Natural Gas Long-Term Load Based on SVM-GA
  • Dong Mingliang,Liu Peisheng,Pan Zhen,Wen Jiangbo,Li Bingfan
  • 2017, 37 (2): 31-36. DOI:10.3969/j.issn.1672-6952.2017.02.007
  • Abstract ( ) PDF ( 2990KB ) ( )   
  •       Long-term natural gas load forecasting can solve the problem of the imbalance between supply and demand of city gas and provide assistance for the city gas company's management and running. In order to improve the accuracy of predicting the longterm natural gas loada forecasting model of natural gas longterm load was built based on SVM-GA(Support Vector MachinesGenetic Algorithm). The relevant factors influencing natural gas consumption was analyzed and determined. In order to improve prediction accuracy the penalty factor c and the kernel parameter g of support vector machines were optimized using genetic algorithm and cross validation methods. Optimized parameters were inputted support vector machines model and long-term natural gas load forecasting was made. In a case study from a certain citya comparative analysis was made of the forecasting results among SVM-GASVM and crossvalidation method combined prediction model and BP(Back Propagation) neural networks. The forecasting model based on SVM-GA was validated with a high prediction accuracy and the resulted relative mean square errornormalization mean square errornormalization absolute square errornormalization rootmean square error maximum absolute error resulted from the SVM-GA were lower than those from SVM and crossvalidation method combined prediction model or BP neural networks by 0.58%3.98%2.99%4.58%8.64% and 6.13%26.28%19.71%21.09%31.48%. Thereforethe support vector machine and genetic algorithm combined model can accurately predict the long-term natural gas load.

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  • Study on Mining Failure Law of Tight Reservoir
  • Xu Yang, Yang Shenglai, Zhang Zhandong, Han Wei
  • 2017, 37 (2): 37-41. DOI:10.3969/j.issn.1672-6952.2017.02.008
  • Abstract ( ) PDF ( 4770KB ) ( )   
  •       There is usually a starting pressure gradient in the tight oil. This article considers the seepage law of the crude oil flowing from the matrix to the fractures in the formation under the premise of starting the pressure gradient and some assumptions. Through the establishment of numerical model, the relationship between the pressure, permeability, core size and other factors and the degree of failure recovery in the onedimensional space is analyzed, as well as the threedimensional plate is drawn. The results show that when the core scale is very small, the main factors affecting the degree of recovery are the failure pressure difference. At the same time when the scale increases, the relationship between the recovery degree and the core length and permeability is more and more significant. Then, based on the conclusion of the previous the paper put forward the empirical formula considering the degree of calculation and recovery under various factors, and extend the space to three dimensions. On the basis of one dimensional revise the formula, the empirical formula of the failure rate of three dimensional matrix failure is obtained. It provides some reference for production practice.

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