Based on a systematic evaluation of the effects of the early-stage water injection test

we studied water flooding schemes for multi-well fracture-cavern units of carbonate reservoirs in the Tahe oilfield through numerical stimulation.These schemes include the optimal timing of water injection

injection-production well network

the types of reservoirs and the relative vertical locations of injection and producing intervals

etc.For a specific type of reservoir

the optimal time to begin water injection should be determined according to its pressure maintenance levels.For cavernous reservoirs

water injection should begin at a pressure maintenance level in the range of 80% to 90%;for vuggy reservoirs

it should begin at a pressure maintenance level over 90%;while for fractured reservoirs

it should begin at a higher pressure maintenance level.An areal well pattern is preferable in water flooding.It is favorable to inject water in fractured reservoir interval and produce oil from cavernous reservoir intervals or from vuggy reservoir intervals

or to inject water in lower reservoir intervals and produce oil from higher reservoir intervals.