Fluid Dynamic Characteristics In Typical Slope Areas In Qikou Depression And Its Effects On Hydrocarbon Accumulation

A large number of research results show that formation water has a close relationship with the formation and distribution of oil and gas,and fluid dynamic has an important influence on oil and gas transportation and accumulation.The Qikou depression displays the tectonic pattern of multi-bulge-multi-slope-multi-depression,and a large amount of oil and gas is distributed and enriched in the slope area,so it is of great significance to study the influence of fluid dynamics on oil and gas formation in slope area,which is of great significance for enrichment the theory of oil and gas reservoir in the continental rift basin and guiding the exploration practice.Therefore,based on the data of formation test,logging,seismic and geochemistry,using mathematical statistics and the principle of hydrodynamic system,this paper studies the characteristics of the formation hydrochemical field and hydrodynamic characteristics of different slopes and different positions of the slope by means of the principle of fluid dynamic system,compares the oil and gas reservoir conditions in different hydrodynamic systems,analyzes the law of oil and gas distribution,and summarizes the oil and gas reservoir formation pattern.The main understandings concluded in this paper are:(1)The TDS is very low,with the characteristics of high sodium chlorine coefficient,low metamorphic coefficient and Na HCO3 water type,which reflects the depression is a typical open freshwater continental rift lake basin.There are great differences in different slope areas,the closure of Banqiao slope is the worst,the closure of the Qibei area is the best,and the internal changes in the Qibei area is great.(2)Qikou pression is divided into 3 pressure bands on the vertical,combined with the characteristics of the pressure and hydrochemical field,the Qikou depression can be divided into three hydrodynamic systems: infiltration hydrodynamic system,hybrid and deposition hydrodynamic system.(3)The reservoir forming conditions of the three hydrodynamic systems are obviously different in hydrocarbon generating capacity,sand body reservoir property,oil and gas filling power,etc.(4)The distribution of oil and gas in the three dynamic systems show regularity.The main types of oil and gas reservoir change from stratum to structure to lithologic.The physical properties of oil and gas also change regularly.(5)The infiltration hydrodynamic system is unconformity-sand body-fault far source filling pattern,the hybrid hydrodynamic system is sand body-fault near source filling pattern,and the deposition hydrodynamic system is near source/in source filling pattern.