Abstract:

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.

Key words: water flooding, development effect, multi-well fracture-cavern unit, fractured-vuggy reservoir, Tahe oilfield