Fluid Effects Of Cbm Wells In Fukang Block

The Fukang block has complex formation condition.It’s in the overthrust plate and it has a huge number and large inclination of coal seams.Also it has thick recoverable coal seams,large cumulative thickness and many target production kayers of CBM wells.The fluid effects study of CBM drainage wells of steeply inclined reservoirs is beneficial to the feature analysis of CBM wells.Also,it’s useful to guide later production of CBM wells in this research area.Through the study of sequence stratigraphy in this area,using the existing spontaneous potential logging data and gama ray logging data,with the results of drilling and pumping experiments,the aquifers and aquifuges of coal are identified and the sequence stratigraphy and water bearing system of the coal strata in the Fukang west block were divided,and the characteristics of each sequence and water bearing system were analyzed.It created the foundation for the later recognition of water source.The water samples from the CBM wells in Fukang area were tested and existing borehole pumping experiment results were collected.The water samples are found by the method of the clustering analysis and entropy weight fuzzy comprehensive evaluation.The results indicated that most water samples were from the lower water system of Ba Daowan formation.The water samples of the two wells FS-26 and FS-39 were determined that they were from the the upper aquifer system of the Ba Dao wan formation.All of the above were calculated by the mathematical analysis method.The hydrogen isotope exchanges among the water from surrounding rocks,hydrogen sulfide gas and itself were happened,resulting the hydrogen isotope negative excursion of drainage water.Through the analysis and study of the data from the CBM wells in the Fukang block,with the results of the nuclear magnetic resonance test,the mercury pressure test and the scanning electron microscope test,the gravity water,free gas and water-soluble gas in the drainage area were calculated.According to this,the CBM wells(CSD01,CS5-xiang1,CS16-xiang 1)were divided into three stages,water dissolving stage,water soluble gas and free gas production stage and desorption gas extraction stage.The influencing factors of drainage fluid effects were analyzed from the factors such as drainage system,coal reservoir pressure,water content of reservoir,reservoir permeability,pore size distribution,connectivity of pore and fissures and the filling features of pore and fissures.