Optimization of Coiled Tubing Interventions on Extended-Reach Openhole Completions in a Field in Saudi Arabia

Abstract

ABSTRACTDrilling new generation wells with longer horizontal sections, to maximize the reservoir contact, has brought many challenges to well interventions using Coiled Tubing (CT). In most cases, the complexity has pushed CT interventions to the limits, driving the development of new solutions to extend the reach to total well depth.The number of these extended-reach wells has grown significantly in recent years in Saudi Arabia, especially in this new development field where more than 120 extended reach water injection wells were placed in the reservoir flanks. The water injection wells in this study area are complex due to the combination of large bore tubular, lower reservoir pressure and horizontal openhole (OH) completion, with lengths from 3,000 ft to almost 5,000 ft.During the initial CT i nterventions in this field, several challenges were encountered, e.g., stuck CT differentials, slack-off weight through severe doglegs, tight spots, and other obstructions. Extensive knowledge was gained by performing an extensive simulation, studying the horizontal section geometry and analyzing the operational data. Based on the findings, combinations of techniques were introduced to the procedure to extend the reach and minimize the operational problems and costs.The key components of our new implemented strategy were buoyancy reduction by using nitrified fluids and new viscoelastic surfactant (VES) friction reducer or drag reduction agents. In addition, combinations of other techniques were employed, e.g., optimizing the pull tests frequency in the OH and improving CT movement practices.This paper discusses the difficulties and challenges of the initial stage of the stimulation campaign, performed in horizontal OH water injector wells using CT. Also, it presents the results and analysis of the effect of buoyancy, CT pipe size and new friction reducer for the referenced wells. The study leads to a new cost effective and reliable technique, which once implemented, conduces to maximize the CT reach without using mechanical devices, e.g., agitators or tractors.