Optimization of Coiled Tubing Interventions to Stimulate Extended Reach Water Injection Wells in a Field in Saudi Arabia

摘要

Drilling wells with longer horizontal sections to maximize the reservoir contact has brought many challenges to the well interventions using Coiled Tubing (CT).In most cases,the complexity has pushed the CT interventions to the limits,driving the development of new solutions to extend the reach to the total well depth.The number of these extended wells has grown significantly in recent years in Saudi Arabia,especially in new development fields like the study area,where more than 100 extended reach power water injection wells were placed in the reservoir flanks.The water injection wells in this study area are a typical example of complexity due to the combination of large bore tubular,lower reservoir pressure,and long horizontal openhole completion,with lengths between 4,000 to almost 8,000 ft.During the initial CT interventions in this field,several challenges were encountered,e.g.,stuck CT due to pressure differentials and slack-off weight through severe doglegs,tight spots,and other obstructions.Extensive knowledge was gained by performing an extensive simulation and study of the horizontal section geometry,and analyzing the operational data.Based on the findings,a combination of techniques was introduced to the CT intervention procedure,to extend the reach and minimize the operational problems and costs.The key components of our new implemented methodology were buoyancy reduction by using nitrified fluids and friction reduction by using new viscoelastic surfactant (VES) friction reducer.In addition,combinations of other techniques were employed,e.g.,optimizing the pull tests frequency in openhole and improving CT movement practices.This paper shows the effectiveness of the new cost effective and reliable methodology to maximize the CT reach up to 8,000 ft allowing the distribution of the acid stimulation throughout the entire horizontal sections.