Dongting Lake Basin Biogenic Gas Geochemical Exploration And Resource Prospect Forecast

Dongting lake basin of hunan province is located in the west on the edge of the palaeozoic era,the Mesozoic and Cenozoic relatively stable in the fault basin there is a continuous sand shale deposits.According to the domestic and foreign gas reservoir case study and basin found several continued for many years since the gas seedlings exposed situation,the possibility of speculation has formed a certain scale gas reservoir in this area and conditions.From 2013 to 2015,the author with university of geosciences(Beijing)in hunan province,dongting lake basin is a biological gas geochemical reconnaissance exploration work,through system of surface sediment geochemistry survey,investigate the leakage in a basin and shallow sediments methane anomaly distribution and geochemical characteristics,recourse to research the source of alkane gas anomalies,hydrocarbon properties and the relationship between the shallow and deep hydrocarbon source rocks of abnormal,biogas in dongting lake basin,in order to solve the "have to","where" and "good" and so on specific issues.A total of three years to complete work:geochemical survey involving an area of 1564 km2,976 total samples,including:935 soil samples,water samples from 38,gas sample 3.The detailed investigation area:area of 200 km2,sampling,162 soil samples;The mercury sample two line a total of 187 samples;Article 2 the wide-area electromagnetic experiment section 24.5 kilometers.Through experimental analysis to obtain:the top air(free hydrocarbon)and acidolysis hydrocarbon geochemical data;Two electromagnetic field of mercury data and reveal the sedimentary characteristics section.The exploration results show that the existence of five significant top air methane migration and three significant acidolysis hydrocarbon migration;Hydrocarbon gas has the geochemical characteristics of biological bacteria solution spirit.1,ruanjiang sag of the Northern Slope,green tree mouth town-heba anomaly zone:methane anomalies in this area is high background values,the abnormal level of 20 times higher than that of other regions,with a high background and acidolysis hydrocarbon annular anomaly and the top of the roof air anomaly superimposed geochemical characteristics,is one of the most perspective and may get breakthrough biogas resources distribution;2,ruanjiang sag belly grass tail in dongyang town Luo Zhou grass tail town west of the town of anomaly zone:high high background,sedimentary thickness,distribution of the characteristics of the area is large.3,depocenter AnXiang sag north rim time migration of concave three fairy lake:abnormal low background,is the largest area,the most obvious feature of the sedimentary thickness.Geophysical exploration work to prove:green tree mouth town-heba methane,high value anomaly zone and mercury anomalies confirmed in accordance with the old channel distribution;The area has abundant quaternary sedimentary sand mudstone,biogas generation and storage of goods and materials.Existing results verify:green tree mouth town-heba anomaly zone is the most thick deposit in this area,methane top air and acidolysis hydrocarbon anomaly is the most prominent biological favorable gas accumulation zone.The specific location of biogas accumulation migration system depends on the follow-up basin research and regional geochemical fine check work after the comprehensive research to determine.