Study On The Grey System Theory In The Prediction Of Coalbed Methane Resources

Size and distribution are the important parts of the coalbed methane geological evaluation and the main bases for the economic budget before coalbed methane development. Whether coalbed gas resources have been calculated accurately or not effect the economic benefits of coalbed gas development. Our country is rich in coalbed methane and has gained a lot of achievements in geological theory and exploration technique after more than ten years of study and exploration. But how to summarize a set of coalbed gas resources evaluation method suitable for geological characteristics is still at the starting stage. So, it's very necessary for us to further study the prediction of coalbed gas resources.Coalbed methane content is a very important factor for the calculation of coalbed methane reserve. So, the study on the prediction of coalbed methane content is of great realistic meanings. Grey system theory was applied to the prediction of coalbed methane content in the mid-south part of QinShui basin. First, a new grey relation degree quantitative model was presented after the comparison and study of many kinds of grey relational formulas and was applied to the analasis of the main factors affecting the coalbed methane content, relational results corresponding with the geological conclusions and having feasibility. Then the traditional GM(1,1) model was improved according to the data characteristics of coalbed methane sequences.Buffer operator optimization GM(1,1) model was presented by constructing several strengthening and weakening buffer operators. Optimization GM(1,1) model was established by improving the background values and initial conditions of the traditional GM(1,1) mode at the same time and applied to the coalbed methane content prediction of the deep coal seam in the study area after its precision tested. Accumulative reduction equal interval GM(1,1) model was presented after existing non-equal interval GM(1,1) models have been studied and improved and its successful application in the coalbed methane content prediction widened the application scope of GM(1,1) model. This paper established the quantitative forecasting models between coalbed methane content and coal seam buried depth, Ro and ash content, and also applied GM(0,N) model to the prediction of coalbed methane content then proposed the grey neutal network GM(0,N) model by combining BP network and GM(0,N) model making it have higher precision than single model by further study on its modeling procedure.This paper calculated the coalbed methane reserves in the study area according to reserve categories, different blocks and coal seams utilizing volumetric method after forecasting the coalbed methane content using grey forecasting model, then evaluated the favorable exploration blocks of coalbed methane utilizing the improved grey clustering methodbased on exponential whitening weight function and selected fanzhuang-panzhuang block ang qinshui-yicheng blocks as the favorable exploration blocks . During the study, in order to simplify the application of grey system theory , the program is realized the main algorithms of the grey system theory utilizing Visual C++6.0 and Matlab7.0.