Migration And Accumulation Characteristics Of The Yanchang Formation In N Area Of Nanniwan Oilfield

The middle combination of Yanchang Formation in N area of Nanyiwan Oilfield in the southeastern slope of Yishan Basin is a typical tight sandstone reservoir.Previous researches on reservoir characteristics,sedimentary evolution and accumulation characteristics of the target reservoir are mostly carried out,while there are few studies on the migration and accumulation process of tight sandstone oil and gas.Based on the data of drilling,logging,logging and analysis and testing,the paleopressure caused by undercompaction during the period of maximum burial depth is recovered by using equivalent depth method,and the plane and section distribution maps of the excess pressure are drawn,and the spatial distribution characteristics are evaluated comprehensively.The basin numerical simulation software is used to recover the formation pressure in the key reservoir forming period.Based on the results of previous studies,the main accumulation periods are determined.According to the development of fractures and the connectivity of sand bodies,the migration channels of oil and gas are determined.Based on the classification of reservoirs,the porosity of different types of reservoirs in key accumulation periods is recovered,and the oil and gas resistance of different types of reservoirs is quantitatively calculated.Through the comparative analysis of the possible migration force and resistance of oil and gas in the key accumulation period,the main migration force of oil and gas in the tight sandstone reservoir of the target layer in the study area is determined.Combined with the factors of migration resistance,migration channel,migration phase and migration period,the characteristics of migration and accumulation process of oil and gas in the target layer in the study area were determined.It is concluded that that the excess pressure of the Chang 7 source rock reaches the maximum in the period of the maximum burial depth,and the formation evolution shows that the excess pressure reaches the maximum at 100Ma,and the pressure decreases at the present time under the influence of various geological factors.The maximum excess pressure of the formation profile is in the Chang 7 source rock,and the maximum excess pressure of the plane is in the middle of the study area.The migration force is mainly the excess pressure difference between source rock and reservoir.Different types of reservoirs are affected by various diagenesis,and the corresponding porosity is different,and the resistance of oil and gas migration in the pores of different types of reservoirs is also different.The main migration channels are fractures and pore sand bodies.The main accumulation period is the end of early Cretaceous.The unique migration and accumulation characteristics of tight oil and gas in the formation are formed under the combined influence of migration force,migration channel,migration phase,accumulation period and migration period.Through the study of the above contents,it is expected to enrich the theory of tight oil migration and accumulation,and provide reference for the later research on the characteristics of tight oil migration and accumulation process and exploration and development.