Innovative Hard-Scale Wellbore Cleanout with an Abrasive High-Pressure Jetting Technique to Regain Well Access and Overcome Challenges: Case Study from Egypt

Abstract A novel approach addresses severe hard-scale buildup in the wellbore, a condition that hinders both well productivity and injectivity, as introduced in this paper. Cleanout operations to restore well accessibility often rely on conventional jet nozzles with coiled tubing (CT). However, variables, such as wellbore trajectory, depletion, fill type, and fluid parameters, can restrict the success of these techniques. The goal is to provide a productive and economical method for production improvement and well accessibility restoration. Conventional jet nozzles often fail to remove hardened scale because of insufficient jet pressure. In some instances, scale hardness exceeds the applied jet force, even with high-pressure jets and rotation-based tools. Under such conditions, wellbore accessibility restoration typically involves milling operations or rig workovers with mechanical drill bits. However, milling tool size selection depends on the smallest inner diameter (ID) necessary to pass through, which can cause improper scale removal inside larger casing sections. Milling can also result in an increase in operational costs. Two injector wells are discussed, which experienced injection rate declines of more than 80% because of the approximately 500 ft of hard-scale deposition that blocked the perforated intervals within the 7-in. casing. This obstruction resulted in a significant production drop from the producer wells supported by these injector wells. Several attempts to conventionally clean the wellbores and restore injectivity through conventional fluid washing and acid batch treatments failed to penetrate the fill, even with high-pressure jet tools. A workover appeared to be the only feasible option for injectivity restoration. However, an innovative abrasive jet technique applied through the CT restored access to the wells through the facilitation of a full rigless cleanout, which saved time and costs associated with a workover. A novel high-pressure abrasive jet method for scale removal and wellbore cleanout is presented. This method breaks down hard scale through a powerful jet of abrasive gelled fluid to restore the injection rates required to enhance productivity in the producer wells. High-pressure jet applications enabled wellbore access and resulted in efficient, dependable, timely, and cost-effective scale removal.