Research On Concentration Conditions And Resource Potential Of Water-soluble Gas In North Songliao Basin

In this paper,geochemical tests were carried out to confirm the geochemical characteristics of the formation water,natural gas types and composition characteristics of the formation water and natural gas samples that collected from the geothermal wells in the north of Songliao Basin.According to different water-soluble gas development layer,water-soluble gas logging identification chart is established respectively,to carry out old well log data reprocessing and interpretation,water-soluble gas accumulation area,and optimized five geothermal wells which are rich in water-soluble gas for system observation to obtain each well natural gas solubility.The geological conditions of water-soluble gas enrichment were analyzed by using oilfield geology,geophysical prospecting,logging and drilling data.Based on the reservoir data,the amount of water resources in the reservoir is calculated.Finally,the water-soluble gas resources in the study area are calculated according to the water-soluble gas abundance value and the water resources in reservoir.This study made the following conclusion and understanding:(1)In order to determine the type of water-soluble gas and composition characteristics,collecting some natural gas samples from the geothermal wells which are rich in water-soluble gas in the study area,and geochemical analysis is carried out,the analysis results show that the water soluble gas in north of Songliao Basin is mainly composed of methane,methane content is 68.52~92.5%,the vast majority of the coefficient of methane above 0.9,which characterized of dry gas,methane carbon isotope is between-75‰~-55‰,the types are mainly biogenic gas.(2)Well logging interpretation method established for optimal block identification of reservoir fluid properties better,not only can better identify gas and water layer,also exist for three-phase fluid situation,foundation to distinguish earlier with oil,and gas water identification.The coincidence rate of the interpretation plate is more than 95.4%,and the purpose of evaluating the fluid property of the optimal block is achieved.(3)Based on the determination of water-soluble gas development area in the study area,the method of identifying water-soluble gas was established for different water-soluble gas development layers,and the re-treatment and secondary interpretation of well logging data were carried out.It is clear that the Du 24 Block in Taikang bulge and Tower 161 block in Longhupao terrace have a good water-soluble gas resources.(4)Collecting data is rich in geothermal well water-soluble gas,optimization five typical geothermal wells pumping system observation and test to obtain each well gas solubility,the test results show a good water-soluble gas display,and the gas daily production is between 190~690m3.(5)Through the test of water-soluble gas wellhead and the evaluation of gas source rock gas content,it is found that the water-soluble gas abundance value is mainly between 0.05~0.35m3/t.The abundance of high value distribute in the Tangchi,Dumeng,Lindian,Anda,and south of Changchun area,as water-soluble gas developed area.(6)The use of water-soluble gas abundance value and the reservoir water resources results in northern Songliao Basin,the two and three member of Yaojia formation,the first member of Yaojia formation,two and three member of Qingshankou formation,the three and four member of Quantou formation reservoir and the resource quantity of water-soluble gas are calculated.The results show that the total amount of water-soluble gas in the north of Songliao Basin is about 2614.19×108m3.