Coalbed Gas and Shale Gas Resource Prospect of Heyang-Hancheng Area

Abstract As an important coal production area, Heyang-Hancheng has already reached coalbed gas exploration stage. However past study had been focused on coal resources survey; systematic oil gas resources assessment had never been conducted. Based on sediment environment research, this paper using field coal survey data combined with source rock organic geochemistry analysis, argillaceous shale and coalbed aero field absorption and resolve tests, isothermy absorption tests, coalbed gas well logging and gas well logging methods etc. to assess the coalbed gas and shale gas exploration prospects. Resource rock of this area is widely distributed and rich in organic matters, has plenty of type II kerogen, and its organic maturity reaches post mature dry gas stage; thus, has sound hydrocarbon production potential. Both coalbed gas well-logging and isothermy absorption indicated gas content has reached resource evaluation criteria; both shale gas in-situ desorption and gas well-logging show existence of gas, and the natural gas is mainly methane (CH4) with heavy hydrocarbon component.Introduction. Locates at the intersection of Hancheng and Chenghe Mining Area in Weibei Coalfield in Hancheng City and Heyang County, the study area has a width of 20.14km from east to west, length of 22.58km from north to south, with an irregular shape and has a total area of 300km2. The area, rich in coal resources, is an important coal resource producing area with widely distributed coal-bearing construction and good continuity. The loess covers a large part of area, and the bedrock is intermittently exposed along the valley. The structural position is in the turning position of the anti-“S” type head in the Weibei coalfield, which is not conform to the monoclinic structure of the NW or NNW, and the dip angle of the stratum is 3°∼7°. The faults are all normal faults, with strike of NE or NEE, usually less than 10 km, the section dips NW, and the fault scale is generally tens of meters to more than 100 meters. The northern fault is mostly southward, and the southern fault is mostly northward, which together forms the NEE direction asymmetric composite garben structure.