It is desirable to establish an injection-production well pattern that can reflect the complex fracture-vug structure and connectivity of the fractured-vuggy carbonate reservoir in Tahe oilfield.The fracture-vug spatial structure characteristics of reservoirs of weathering crust type

fault-controlling type and underground river type were comprehensively analyzed in the geological contexts of various karst types.These in combination with the analysis of characteristics of injection-production relationship and basic well patterns led to the concept of "injection-production spatial structure well pattern".It is to establish the relationship of injector and producer in a three dimensional space based on the spatial distribution of fracture-vug complex and in combination with parameters of fracture-vug such as morphology

scale and connectivity

so as to maximize control of fracture-vug

producing reserves of waterflooding and recovery factor.The results show that the injector-producer relationship for reservoirs of weathering crust type is characterized by "injector at lower location and producer at higher location

injection through fractures and production through vugs

injection through smaller vugs and production through larger vugs

thus "plane" injection-production well pattern is suitable.The injector-producer relationship for reservoirs of fault-controlling type is characterized by "isoheight injection and production

injection through fractures and production through vugs"

thus banded injection-production well pattern should be adopted.The injector-producer relationship for underground river type is characterized by "injector at lower location and producer at higher location

injection through vug and production through vug"

thus linear injection-production well pattern is suitable.In addition

differential water injection schemes should be selected according to the well pattern

so as to realize the goal of this concept

i.e.multi-direction injection-production

multi-segment injection-production and spatial injection-production.