Research On The Favorable Hydrocarbon Generating Layer Section Of Mohe Formation At The Mohe Basin Northeast China

Natural gas hydrate as a new type of unconventional energy, due to its high energy density, wide distribution, large scale, shallow buried and other characteristics, is considered to be the important alternative energy resource of oil and natural gas in the future.The permafrost region of Mohe basin has good metallogenic conditions and prospecting potential of natural gas hydrate,but has not been made important progress,Compared with the Qilian mountain region of natural gas hydrate has been found,the surface temperature, geothermal gradient, the thickness of the permafrost between the two has little difference. in addition, tundra has sufficient underground water condition and groundwater salinity is lower which is good for the formation of gas hydrate.Predecessors on the basis of regional geological survey and experiment analysis coupled with comprehensive drilling, seismic data research at present,which shows that the sedimentary thickness of Mohe Formation in Jurassic at the Mohe Basin is large and dark mudstone is development, has the most hydrocarbon generation potential in Jurassic at the Mohe Basin.Therefore, to carry out the research on the favorable hydrocarbon generating layer section of Mohe Formation in Jurassic at the Mohe Basin,which has great significance for the furture exploration about gas hydrate at the Mohe Basin.In this paper, Based on the drilling core samples from the three drilling cores which were serving for seeking natural gas hydrate as research object, by systematic stratigraphy, sedimentology, inorganic geochemistry and organic geochemistry analysis, the analysis results show that:(1) The deposition of Mohe Frmation at the Mohe Basin mainly belongs to braided river delta facies, next lacustrine deposit, in a anoxic, reducing and slight salt to brackish water sedimentary environment,Humid climate conditions, which can provide conditions for the formation of favorable hydrocarbon source rocks.(2) The organic matter abundance of hydrocarbon source rock samples in research area varies greatly, mainly belongs to moderate to good hydrocarbon source rock, has better hydrocarbon generation potential; the type of organic matter generally belongs to Ⅲ-type including a little Ⅱ2-type, benefiting for the generation of the natural gas.The thermal evolution of the source rock generally belongs to maturity to over maturity stage, little in the immature stage, mainly generating wet and dry gas. In conclusion, the hydrocarbon source rocks in the research can be used as good gas source rocks, has great potential of generating natural gas.(3) The good quality intervals of hydrocarbon source rocks in research area has the high quality V,U content, low Sr/Cu value, the medium of V/(V+Ni) value, high or low equivalent boron content. Theseindicate that the good quality intervals of hydrocarbon source rocks in a anoxic, reducing, humidity, salt or fresh water sedimentary environment. But in general, the moist and warm climate, anoxic, moderate salinity environment makes the good hydrocarbon source rocks.(4) The favorable hydrocarbon generating layer section at the Mohe basin mainly focus on J2m1 and J2m2. At the same time, the upper layer of J2 er in some regions is also likely to be the favorable hydrocarbon generating interval.These favorable hydrocarbon generating intervals can supply the gas of the gas hydrate, which are the important intervals for future exploration.