Fracture-cavity Reservior Characterization On Renqiu Buried Hills

Renqiu buried hill producing reserves has decreased with continuous increasing degree of reserve recovery since it was exploited in 1976,especially at the later stage of development with high water cut,OWC rising and water flooded area extending lead to complex residual oil distribution,which affects reservoir ultimate recovery using existing technology.Fracture-cavity reservoir research is the key to determining residual oil distribution types and treatment method.Therefore,fine reservoir characterization study will be carried out to demonstrate the fracture-cavity characteristics and distribution,to find out the relationship between fracture-cavity distribution and subsurface fluid distribution and to classify reservoir type.Consider dynamic production to analyze the influence of reservoir production and development made by fracture and cavity in order to direct reservoir development.The key technology include FMI,interwell tracer testing analysis,conventional log interpretation,core analysis and dynamic production analysis.The study emphasized on description of reservoir space characteristics including pore,fracture and cavity,established the fracture-cavity reservoir division standard,solved the problems of previous division and divided Renqiu buried hill reservoir into three categories ?,?,?.On the basis of fracture-cavity reservoir classification,evaluate reservoir properties with conventional logging,establish the relationship not only between fault and fracture-cavity,but also between fracture-cavity distribution and residual oil distribution,predict reservoir spatial distribution of buried hill using well drilling and logging data.The study demonstrated three kinds of reservoirs overlying,which resulted in areal heterogeneity,while all kinds of reservoirs develop in different depth and fracture is more developed on the top of the buried hill,mainly inducing?&? reservoir.Heterogeneity is proved to play an important part in producing.That means the higher of reservoir grade is,the more fracture develops.The characteristics of such reservoir are high individual well productivity at early stage,long water free production period,low ascending velocity of OWC&water cut and high cumulative oil production,etc.