Development Parameters of Chang 6 Reservoir in Shuanghexi Block of Yanchang Oilfield,Ordos Basin
The Chang 6 reservoir in the Shuanghexi block of Yanchang oilfield in the Ordos basin is characterized by low permeability.Con-ventional calculation methods for development indices are not conducive to geological research,policy formulation and cost control for oil-field development.The production decline patterns,producing degree of reserves by water flooding,injection-production ratio,water cut,in-jected water utilization,and recovery of the Chang 6 reservoir were analyzed.The results show that the production of the Chang 6 reservoir follows a hyperbolic decline pattern.The block has significant potential for water injection development,with the current control degree and producing degree of reserves by water flooding at 74.54%and 36.94%,respectively,and an injection-production connection rate of 27.27%.The optimal injection-production ratio is approximately 2.5.As the recovery efficiency increases,the water cut rises rapidly at the first and then slows down.Based on the water retention rate,water consumption index,and water flooding index,it is evident that in the late stage of development,the water injection effectiveness improves,leading to an increase in ultimate recovery.During the development pro-cess,the water cut rise rate should ideally be kept below 6.1%,and the reasonable formation pressure should be maintained above 9.1 MPa.Under these conditions,the final recovery in the study area is approximately 23%.
Ordos basinChang 6 reservoirdecline patternproducing degree of reserves by water floodinginjection-production ratiowa-ter cutinjected water utilizationrecovery
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