Studies Of Dynamics Of Petroleum Accumulation On The Northern Dongpu Depression

The research object of this paper is Northern Dongpu Depression. Based on the main study on the spatial distribution of geo-therm field and the impact of gypsum-salt rock on geo-therm field, pool-forming dynamic system is divided and its characteristics are described, and the pathway system, resume accumulation period , law of hydrocarbon distribution and pool-forming models are analyzed.The article calculates pressure to analyze the distribution of the modern geo-therm field with testing data and ultrasonic travel time difference method and recover the ancient temperature and pressure with inclusion thermometry and basin modeling methods. The plane distribution of modern geo-therm field corresponds to the tectonic framework of the studied area. Formation pressure can be vertically divided into three zones as following: normal pressure zone, over-pressured zone and ultra-high pressure zone and the heat conduction effect of gypsum-salt rock influences the distribution of geo-therm field in some way. The reasons of the origin of abnormal pressure mainly include under-compaction, the reserve of abnormal pressure with gypsum-salt rock, lateral sealing and vertical draining of faults, hydrocarbon generation, and so on. The main controlling factors in different areas vary. The ancient pressure originally accumulated at Es1, Es2 and Es3 stages, and reached the maximum at the end of Es1 sedimentary period. Over pressure released at the sedimentary period of Dongying group and has been re-accumulating from then on and paleotemperature also has the evolution trend of"increase-decrease-increase". Modern hydrocarbon in all formations mainly accumulates where residual pressure is low and geothermal gradient is high. Based on the study on formation pressure system and combined with the study on structure-sedimentation, the distribution of gypsum-salt rock, the source of hydrocarbon and petroleum geologic features, the studies area is divided into 9 systems on plane and every system is named and described. With inclusion analysis, the fluid of Es3 group filled at the end of sedimentary period of Dongying group. Combined with the spatial distribution of gypsum-salt rock, there are three pool-forming patterns, which are source- mixed and open pattern above gypsum-salt rock, source- mixed and closed pattern among gypsum-salt rock and close self-source pattern below gypsum-salt rock.