A new oilfield injection water quality decision-making method

Due to long-term water injection development, the formation permeability will continue to decline. The water injection quality selected before the water injection development cannot always meet the water injection demand of the reservoir permeability. In order to reduce the damage of the water injection water quality to the reservoir, it is necessary to re-select the appropriate water injection water quality. This article proposes a water quality decision-making method considering the history of water injection. According to SY/T 5329-2012 standard for water quality, water quality sensitivity coefficients are given for reservoirs with different permeability under five different injection water qualities. The sensitivity of water quality was characterized qualitatively and intervals of water quality sensitivity coefficients were determined. Adjust the water quality of the injection based on the consideration of water injection history on permeability injury. After a simulation study it was found that changing the water quality of the injection water could increase the recovery rate by 1.6%. The method is of great significance for the old oilfield water quality and water injection efficiency improvement.