The CBM Enrichment Regularity Of Zhengzhuang Block In Qinshui Basin

The CBM geological condition of south Qinshui Basin is so good that has aresource foundation for CBM exploration and development. In order to ravel outCBM’s enrichment rule of Zhengzhuang block and confirm the main controllingfactor that influence CBM’s collection in this area, we sum the factors that influenceCBM’s enrichment from the two facts celled “macroscopic geological characterizesand microcosmic reservoir characterizes”, through the basic geologic researchingabout the Zhengzhuang block. The macroscopic geological characterizes include suchconditions as structural environment, coal thickness, thermal evolution, coal’sstructure, hydrogenologic conditions and so on. The microcosmic reservoircharacterizes include coal petrography and quality, gas content, permeabilitycharacterizes, mechanical property of the coal and so on. On that basis, we optimizedthe beneficial area of CBM from the Zhengzhuang block, given a classifieddescription to each block from resource condition, tectonic condition, hydrogenologiccondition and so on, established the CBM assessment system that accorded with thephysical truth of Zhengzhuang block. Finally, using the grey prediction method, weoptimized one or two beneficial areas of CBM that not only satisfies the geologicalconditions but also the engineer constructions’ requirement.Researches show that the Zhengzhuang block of Qin Shui Basin is a uniclinalstructure that inclines forward to the NW direction. In this area, the minor fault ismore common and the folds range as a relieve wave. Delta plain facies are the mainsedimentary facies in this area, among of them including some micro sedimentaryfacies such as diversion stream gulf, diversion stream river, flood fan, peat bog, lakeand so on. It is beneficial for the saving of CBM that the roof of3#coal seam is madeof mud stone. However, it is disadvantageous for the saving and developing of CBMthat the roof of15#coal seam is mainly made of thick marls. The whole regionconcludes four main aquifers and the roof of3#coal seam is a wonderful water proof.The transverse distribution of3#coal seam is stable with a generally trend that thenorth part is thick while the south part is thin. The effective thickness of3#coal seamis between2.40-7.35m and average5.39m. The depth of3#coal seam is between383.05-1336.9m with the trend that gradually becomes shallow from north to south.The gas content is between1.51-31.44m3/t and average19.93m3/t. Through theinjecting/pressure dropping well testing method, we tested the original permeability of3#coal seam in the twenty wells of Zhengzhuang block. The data shows that theoriginal permeability of3#coal seam is between0.011-1.9×10-3μm2and average0.20×10-3μm2, which is belong low-middle level. According to these research results,we formulated the reasonable optimizing principles and established the optimumindices and standard evaluations. In the end, we selected the area from ZS45well toJS10well and from ZS73well to ZS102well as the most favor target zone.