Study On The Hydrocarbon Migration And Enrichment Regularity Of Oil And Gas Of Paleogene Formations In Jinxian Sag

The migration and accumulation of oil and gas reservoir in lacustrine basin has been on the hot topic in the field of oil and gas exploration. Based on GIS (Geographic Information System),Using the drilling, logging and seismic data to do the research for reservoir characteristics, oil and gas migration advantages of the channel and Central South Department of oil and gas regional evaluation monographic.To elucidate the control effect of the structural evolution of the sedimentary evolution on hydrocarbon accumulation and its controlling factors. Finally, in the same stratigraphic framework, pointed out that the favorable zone, zone and field, the selection and implementation monolithic scale reserves target favorable exploration direction.Jinxian sag is located in the southwestern part of Jizhong depression. It is separated from Shijiazhuang depression by Wuji-Gaocheng low uplift in the West. The Ningjin uplift divided the Jinxian sag and Shulu depression in the east. There are five tectonic related strata of Paleogene in Jinxian sag, including Ek3, Ek2, Es4+Ek1, ES3+ES2 and Es1+Ed. Those strata reflect the primary features of the tectonic movement of Jinxian sag in Paleogene.The purpose of this study interval includes Ekl-Es2, oil and gas region, plane distribution is more dispersed, vertical overlap is poor. Through the study of reservoir properties in the study area and clarify the law in the study area sandbody cloth. And then provide the basis for an analog channel of the dominant migration pathway system and effective distribution. Through the fault sealing of research and analysis, it illustrates the effect of faults at all levels of hydrocarbon migration and accumulation in Jinxian sag. Factors Affecting Fault Closure:The stress on the fault formation, fault angle, fault-containing shale content. Based on the requirements of quantitative assessment, choosed fault shale smear factor (SSF) to assess the depressed levels of fault sealing.There are three sets of hydrocarbon source rock in the southern part of Jinxian sag, Ek2+Ek3, Es4+Ek1 and ES3+ES2. Ek2+Ek3 is the thickest one, with high abundance of organic matters, which has reached the high mature stage. It is a primary hydrocarbon source rocks in Jinxian sag. Es4+Ek1 is also an important hydrocarbon source rock for Jinxian sag. There is a minor capability for ES3+ES2 source rock, only as a secondary source rock.The hydrocarbon migration is the primary challenge for petroleum geology, especially the migration path prediction. In order to find solution for the challenge, we applied GIS (Geographic Information System) platform, with its spatial database and spatial data processing of geological parameters analysis to simulate the dominant hydrocarbon migration path and to analyze accumulation pattern. As the result, we successfully predicted and assessed the favorable area for hydrocarbon exploration.This study is focusing on the hydrocarbon favorable migrating path and hydrocarbon accumulation modeling to predict the prospective area. We integrated the Geographic Information System platform with spatial data processing and comprehensive analysis, seismic data and geological interpretations, to evaluate hydrocarbon source rock, migration framework, hydrocarbon migration path and favorable zones, analyze the oil and gas accumulation pattern, and primary factors of hydrocarbon migration and accumulation.The micro scale, the oil and gas migration occurred through the void space in the subsurface rock. From a macro view, the void spaces were developed in the geological bodies with permeable strata, fault, unconformity surface. The oil and gas migration path is not isolated; it is a spatial combination of the fluid carrier system from hydrocarbon source rock to final hydrocarbon trapping. The permeable reservoir with primary porosity, secondary porosity or fracture sand reservoir is the carrier bed for hydrocarbon migration. The depositional environment plays an important role for the development of carrier system and connectivity. The pore distribution, permeability, thickness of sand body, the occurrence of geological conditions is an important factor affecting the migration performance. The space settings between carrier bed and hydrocarbon source rocks, within carrier beds, carrier bed and the fault, unconformity configuration will determine the effect of carrier system to the migration of hydrocarbon.There are three hydrocarbon accumulation trends in Jinxian sag: ①The eastern part of the steep slope trend:the development of stratigraphic reservoirs in the slope belt; structural reservoir mainly developed central faulted structural belt, the tectonic and stratigraphic reservoirs, rich in oil and gas accumulation; The western slope trend, it developed stritigraphic up-dip pinch-out reservoir with small scale hydrocarbon accumulation. ②The secondary fault development trend, it controls on the background of structures nose in the slope developed, and also control on sedimentary filling and depression.③The continue activities of primary and secondary fault trend, the primary fault is an open fault and play an important role for vertical migration of oil and gas, oil and gas vertical migration along faults to the convex concave convergent, divergent. Longitudinal slope conjugated fault sealing, lateral connectivity depends on both sides of the fault and sand shale smear factor relation, SSF value.Base on the oil and gas analysis and hydrocarbon fairway migration simulation, study, we believed that the hydrocarbon migration occurred in the source rock, it determinates the hydrocarbon fairway. It also determines the specific block can be obtained the hydrocarbon. The upper layer is not in direct contact with the main hydrocarbon source rocks in where the fault was connected the source for oil supply. The study established the hydrocarbon accumulation models within source rock and over source rock in Tertiary. We recommended that the exploration should focus on the hydrocarbon migration fairway as a primary clue integrated with other petroleum system such as reservoir-seal, source rock to categorize the exploration fairway. Statistics study indicates that there is a very good correlation between the volume of hydrocarbon source rocks and proven reserves. It can be used for relative evaluation of oil and gas resource potential assessment. We completed the hydrocarbon accumulation fairway assessment and prediction for ES3 and ES4 units base on the study of the hydrocarbon accumulation and categorization, a comprehensive analysis of the application of reservoir quality, trap conditions and oil source conditions. It could be a guideline for future exploration activities.