Evaluation method and treatment effectiveness analysis of anti-water blocking agent

The laboratory evaluation method for anti-water blocking agent treatment effectiveness is essential for choosing the excellent anti-water blocking agent to restore the declined well production owing to water blocking. The key point of the evaluation method is establishing the water saturation and measuring the permeability in the process of water blocking damage and anti-water blocking agent treatment. This paper analyzes the complexity and repeatability of different methods for laboratory establishing water saturation in cores. The reasonable simplified treatment for corresponding water saturation under initial reservoir state, water blocking damage state and anti-water blocking agent treatment state are proposed. And then, the evaluation procedures are designed and achieved by core forward flooding and reverse injection according to the enter direction of related fluids into the formation. The treatment effectiveness is characterized by two new parameters, i.e. permeability recovery percentage R-p and permeability recovery ratio R.R. Furthermore, the interfacial properties of a variety of commercial products and surfactants are studied and the corresponding treatment effectiveness is also investigated by the designed evaluation method. It has been found the permeability recovery percentage R-p and permeability recovery ratio R.R are better correlated with gamma(ow)theta(ows) and gamma(gw)theta(gws). And the variation tendency is coincided with the microscopic mechanism of trapping water by capillary force. These experimental results further verify the feasibility of the evaluation method. Therefore, this designed evaluation method provides a common procedure for screening and developing of anti-water blocking agent. (C) 2016 Elsevier B.V. All rights reserved.