Research On The Charge Times Stages Of Deep Natural Gas In The Dehui Depression, The South Songliao Basin

Dehui depression,is located in the center of East fault depression of SE uplift,the south Songliao basin;north Changchun,cross Nong'an and Dehui two counties. The area is south the pine distant basin southeast to stick out east the area to break falls middle the belt,North Changchun,Cross Dehui two counties,The Area is 3,800 square kilometers。After many years exploration research,This area basement rock burial depth generally is 2500~5000m,the center of fault depression to be allowed to achieve about 6000m。The basement is the metamorphic rock of Upper Paleozoic,partially is the igneous rock。Dehui depression is the tectonic units of the senond order,the Songliao basin,the research area further divides into Xiaohelong-Buhai tentonic zones,Xiaohelong Sub-Sag,Central anticlinal tectonic zones,Dehui Sub-Sag,Nong'an dong Sub-Sag and Nong'an-Wan jinta Sub-Sag。In the paper, the anthor researched thoroughly the charge times stages of the deep natural gas in the Dehui depression.The aim of the paper is to clarify the charge stage and time of deep natural gas,to establish filling modes of deep natural gas, in exploration area. In this paper,Firstly, erosion methods are utilized to recovery burisl history of two bell in exploration area. Then the author research systemly the basic features of the saltwater inclusions. Lastly, many methods and techniques are utilized to analyse and test the features and homogeneous temperature of the inclusion, such normal slice identification , transmission polarization observation, fluorescence microscope analysis and cooling-heating platform,etc.Firstly, Ac method was utilized to recovery the shallow erosion for Deshen 5 well and Nong 101 well, the erosion thickness of Nenjiang formation is 401m for Deshen 5 well and 508m for Nong 101 well; Sediment rate method was utilized to recovery the deep erosion for this two well. The erosion thickness of Yingcheng formation is 353m for Deshen 5 well and 445m for Nong 101 well. According to the two well erosion thickness recovery, burial history chart was made. Secondly, thermal history cure is very important to ascertain the charge times stage of natural gas. Dehui depression's thermal history cure uses Mr. He Sheng (He Sheng, 1995), the Lower Cretaceous's geothermal gradient selects 6℃/100m, the surface temperature is 20℃; The Late Cretaceous epoch's geothermal gradient selects 4.8℃/100m, the surface temperature is 8℃; Nowadays the geothermal gradient selects 3.3℃/100m, the surface temperature is 8℃。Finally, utilized microscope the analysis and the test method has conducted the research to the saltwater inclusions type and the basic characteristic,.Thermal history cure and the burial history cure are respectively recovred. Therefore by means of burial history-homogeneous temperature we can confirm deep natural gas filling time of each stage. It is indicated that the homogeneous temperatre of the saltwater inclusions associated with the hudrocarbon inclusions in the Shahezi formation distributes from 120℃~130 ℃,corresponding late Denglouku-early Quantou and late Quantou-late Qingshankou which was about 119Ma~108.6Ma and 102.4Ma~89.3Ma. The homogeneous temperature of the saltwater inclusions associated with the hydrocarbon inclusions in the under Yingcheng formation distributes from 110℃~120℃,corresponding late Quantou which was about 102 Ma. The homegenous temperature of the saltwater inclusions associated with the hydrocarbon inclusions in the upper Yingcheng formation distribute from 110℃~120℃,corresponding Nenjiang time which was about 83.5Ma~76.5Ma. So Yingcheng formation have two times gas injection, one is late Quantou,the other is Nenjiang time. The homogeneous temperature of the saltwater inclusions associated with the hydrocarbon inclusions in the Quantou formation distributes from 80℃~90℃and 100℃~110℃,corresponding Qingshankou time and Nenjiang time which was about 97.6Ma~90Ma and 83.5Ma~72.8Ma, but latter is main time。Deep hydrocarbon gas pool of Dehui depression has three times of natural gas large-scale migration and enrichment, the first time is late Denglouku-early Quantou(119~108.6Ma), the second time is latr Quantou–late Qingshankou (102.4~89.3Ma), the third time is Nenjiang time (83.5~72.8Ma) .