Development of Emulsified System to Remove Organic Scales from Water Injection Wells: Laboratory Analysis and Field Treatment

This paper presents a case study where wellbore organic deposits were cleaned out using an emulsified system. The organic scale deposits exist in a well that was drilled and completed to inject water to maintain the oil reservoir pressure. The water injector well completion was located above a tar formation. The organic deposits in the wellbore affected the injectivity of water and restricted the water injection operations. Samples were collected from the downhole from the water injector well, and these samples were analyzed in the laboratory using IRS (infrared spectroscopy) and extraction by solvents. Laboratory analysis showed that the downhole sample consists of maltene in the form of resins, saturates, and aromatics. The sample contains some asphaltene as well. Extensive solubility experiments were carried out at the downhole temperature using different solvents. Solvents such as aromatics and xylene in diesel were used to dissolve the organic deposits. The optimum formulation in terms of cost, solubility, required time, and chemicals hazards was selected for further field treatment. The emulsified system that was selected for the field treatment consists of freshwater, emulsifier, n-methyl pyrrolidone, and solvent (aromatic). The emulsified solvent system was able to dissolve wellbore organic deposits of Well-X during field treatment, and the well injectivity was restored after the treatment.