Chacteristics Of Temperature-pressure Field And Role In Deep Reservior-formation In The North Zone Of Dongying Sag

Deep basin temperature-pressure system control the formation phase transformation and migration force of hydrocarbon,and it is important basic problem in the study of deep hydrocarbon accumulation dynamics.This paper was to take Es4 stratum in the north zone of Dongying sag as research object and used core, logging, well logging, seismic data and so on, on the base of mudstone compaction study and nowday temperature-pressure field study, built the model of basin temperature-pressure field structure and evolution.Then, under the constraints of fluid inclusions and the measured temperature-pressure data,we used numerical simulation to restore the ancient temperature-pressure evolution.At last, combining the characteristics of reservoir geology,we studied the role of temperature-pressure field in reservior-formation. The main conclusions are as follows:On the basis of fully collection of logging and well logging data in Dongying Depression north part,we acquired 84 mudstone compaction curves. According to the characteristics and comparative analysis, the mudstone compaction curves in the study area are vertically segmentable with depth and also are zonation horizontally.We think that the vertically segmentable with depth is caused by the unconformity in end of Dongying formation,and Lithologic combination, depositional rate and tectonic are the main controlling factors of zonation horizontally.Through the analysis of the current measured temperature data today, we find that the average of geothermal gradient was 3.6℃/100 m,and it has a higher trend from the depression belts to the steep slope zone in northern,meanwhile geothermal gradient with depth increasing has a lower trend. On vertical,overpressure can be divided into shallow normal pressure system and deep overpressure system.Overpressure exists mainly in the downthrow of Shengbei Fault, and the pressure of upthrow is normal; According to the comparetion of mudstone calculate pressure and sandstone reservoir pressure, we think mudstone undercompaction is the main contribution of the overpressure about 60% to 80%, and hydrocarbon generation function is also important contribution mechanism;On the basis of collecting processing geological data in the study area, we established Dongying North basin temis3 d model and three temis2 D model to study the evolution of basin temperature –pressure field. Deep Es4 temperature field was controlled by the burial history of the basin,and sag zone was always high temperature field center. We also found that the overpressure has three major cycles, and the end of Es2,Ed and nowday are three highest vaule periods.On the results of the ancient temperature-pressure evolutionstudy, we think the two main hydrocarbon expulsion period of hydrocarbon source rocks in Es4 s and Es3 x is dongying period and Minghuazhen – nowdays,with high value of abnormal high pressure evolution phase matching, speculatthat abnormal high pressure is an important hydrocarbon expulsion power. Through abnormal high pressure research combined with reservoir diagenetic research, we find that abnormal high pressure can’t seem to effectively restrain diagenesis which cause physical property variation; Secondary dissolution is primary mechanism of abnormal high porisity and permeability in overpressure zone reservoirs.