The Optimization Of Well Pattern For The Complicated Fault-block Reservoirs At High Water Cut Stage

Compared with conventional reservoirs, complicated fault block oil reservoirs are not easy to develop, which have unique geological and development properties, such as, smaller oil area, complicated oil/water contact, uneasy to develop. Therefore, it is essential to study all kinds of factors influenced on water flooding recovery and adopt reasonable development methods in view of unique properties.Based on documents study, statistical analysis and numerical simulation, scientific estimations are made on injection- production system and layer system accommodations of different kinds of fault block reservoirs at high water cut stage. In the practical development, pattern well network is adopted in anticlinal and lithological faults block reservoirs due to relative simple structure; unsealing fault block reservoirs generally have enough natural energy, there are relative fewer problems in injection-production system. For semi-sealing and sealing fault block reservoirs, the recovery depends on water flooding.Applied numerical simulation technology, many influenced factors of semi-sealing fault block reservoirs are studied and analyzed including reservoir parameters(ratio of oil water viscosity, inhomogeneity,edge water,width of oil belt), development conditions(injection/production strategy,well spacing density, water intake per unit thickness, water flooding mobilization degree, liquid withdrawal rate, energy maintenance, water flood timing)and development characteristics and residual oil distribution. Based on methods of reservoir engineering and statistical analysis, a empiric formula about well spacing density and recovery is matched and a calculation method is got to determine reasonable well density and limited well density combining economical assessment.For sealing fault block oil reservoirs, injection strategy, oil control feature and remaining oil distribution feature is summarized, based on small fault block oil reservoir's usual geometry (rectangle,parallelogram,triangle,trapezoid). By numerical simulation and economic evaluation for typical block reservoir, Effective thickness of water injection development and reserve abundance limits of broken block reservoir are determined, which provides evidence for water flooding program. Based on the actual data of xin 11, pressure maintenance level is studed for semi-sealing fault block reservoirs at high water cut stage; combined with the research result of mechanism model, the injection development well pattern scenario is made, and the feasibility of injection development is determined with the final FOE 3.09% more.