Accumulation Distribution Characteristics And Controlling Factors Of Chang 6 Reservoir In A Area Of Panlong Oilfield

Based on the comprehensive understanding of the basic petroleum geological conditions of Chang6 reservoir in A area of Panlong Oilfield,and with the data of core analysis,well-log and laboratory analysis,this thesis studies accumulation distribution characteristics and its controlling factors in the study area from oil source,sand body distribution,structure characteristics and reservoir characteristics.Chang6 reservoir belongs to lithologic reservoir with characteristics of blurring of oil-water boundary,mixture of oil and water,no pure oil reservoir,and most oil reservoir is oil and water reservoir.The oil reservoir in Chang6¹ is the most developed in the four sand formations.The thickness becomes thinner and the distribution area decreases gradually from Chang6¹ to Chang6⁴.The oil-bearing in Chang6^1-1 is the best in the three small layers of Chang6¹.The distribution characteristics of oil reservoir in the longitudinal direction are thin in thickness and many in number.The oil reservoir changes rapidly horizontally,poor in connectivity and presents a character of lenticular distribution.The study area is located in the edge of Chang7 source rock distribution area,and hydrocarbon generating quantity is relatively small,resulting in a large sand thickness and the smaller reservoir thickness and indicating that the oil source is main controlling factor of oil-water distribution.Chang6 sedimentary microfacies are delta front underwater distributary channel and interdistributary bay.Oil reservoir is mainly distributed in the main river channel sand bodies with the NE-SW direction.The high quality reservoir-seal assemblage of Chang6¹ and Chang6² makes their oil-bearing is better than Chang6³ and Chang6⁴.Reservoir lithology,physical properties and reservoir-seal assemblage play important controlling roles in oil-water distribution.Low-amplitude nose-shaped uplifts effect on control of oil-water distribution is smaller.The overall heterogeneity of Chang6 reservoir is stronger,and the influence of oil-water distribution is mainly reflected in the rhythm of permeability,the distribution of interlayers and porosity and permeability in plane.Oil reservoir is generally well developed in the middle and upper part of the positive rhythm and in the middle and lower part of the reverse rhythm.Interlayers influences vertical and lateral migration and accumulation of oil and gas by impeding the flow of fluid and preserving the dissipation of oil and gas.The river channel sand bodies with good porosity and permeability are of better oil-bearing in plane.