Study On The Event Deposition In Continetal Rift- Subsidence Basins

Gaoyou Sag is belong to Subei Basin.The Paleogene strata in the sag have many hydrocarbon-bearing stratas and rich reserves.However,With the oil and gas exploitation is increased in recent years,the resource that have been discovered have not met the demand for oil and gas.In order to increase oil and gas production,the main task of Gaoyou Sag in the future is how to find hidden oil and gas reservoirs.During the dainan Formation period,a large number of geological events happaned in the Gaoyou sag.They can affect the sandstone distribution regularity and Oil-gas Migration pattern.So,The event deposition study was carried out on the Dainan Formation in the Gaoyou Sag.And answered two questions: 1.what is the relationship and difference between geological events.2.how to affect the Oil-gas Migration pattern.Based on the principle of base-level,two scales of stratigraphic cycles(intermediateterm and long-term)could be identified through the Predecessor research results and analysis of cores,logs andseismic data.Then high resolution sequence statigraphic framnwork of Gaoyou sag built.The Dainan Formation's strata was divided into 2 long term base-level cycles and 8 mid-term base-level cycles.Based on the high resolution sequence statigraphic framnwork,and combined with the petrographic characteristics of the sedimentary rocks.Distinguished seismites and tempestites,inertia flows in the Dainan Formation's strata.The seismites was found in the strata of during MSC1-4 and MSC6.The tempestites was found in the strata of during MSC1-5.The inertia flows was found in the strata of during MSC1-4 and MSC7.Under the control of the sand control effect of the "seesaw" in the study area,the trigger mechanisms of several deposition s were discussed.It was thought that the case of inertia flow in the MSC2-4 period of Gaoyou Sag is affected by frequent earthquakes and storms,level rise and fall.Finally,it was discussed that how earthquakes and storms,inertia flows affect the Oil-gas Migration pattern.Figure 52;Table 5;Reference 87...