The Vital Role of Well Intervention Technologies and Techniques in Pushing the Boundaries in Extreme Well Completions

Abstract

The advantages of drilling extended reach wells (ERW’s) are well known; increased reservoir contact, reduced surface footprint and less wells drilled. Although the benefits of drilling these wells is clear, it is also essential to have the ability to conduct well intervention throughout the life of the well. Matrix acid stimulation and production logging are critically important well intervention operations for efficient reservoir management. Coiled tubing (CT) is commonly deployed in ERW’s to perform these intervention operations. For open hole ERW’s, the success of the operation is often directly correlated to the length of the lateral covered. For ERW’s that can exceed 30,000 ft, the challenges to reach total depth (TD) can almost be insurmountable in terms of overcoming the high frictional forces acting against the CT. The level of difficulty is further magnified covering open sections often greater than 10,000 ft, where additional frictional forces are present from the rock, high dogleg severity and well trajectory. High bottom hole temperature along with high H2S & CO2 levels pose further challenges. Formation damage after drilling may result in serious production and therefore economic consequences and it is imperative to restore reservoir permeability along the complete interval with accurate treatment placement. The same challenges are present for logging operations where the main objective is to determine the flow profile along the entire open hole section. To achieve the main objectives, a comprehensive approach is taken for these well intervention operations. Custom designed technologies have been developed to increase the open hole coverage achieved to provide good zonal coverage in matrix acid treatments and also a clearer understanding of multiphase flow from the formation during production logging. Technologies developed specifically to tackle these challenges are hydraulically powered CT tractors that can deliver up to 14,000 lbs pulling force and mechanical agitator tools that effectively reduce the total friction coefficient. Other technologies employed are a downhole compression/tension sub to monitor downhole performance in real time to enhance operational decision making. To extend the ultimate reach, certain techniques can add a few thousand feet in coverage. These techniques include high pressure jetting to clean out the horizontal section of the cased hole to lower the friction, strategically deploying friction reducer and using momentum assiduously. These new technologies and applied techniques opens the window to ultimately meeting the goals of improved well surveillance and treatment in long horizontal laterals. Creative solutions have been core to inventing the best fit for purpose technologies, with great leaps having been made through pioneering technologies to extend CT reach in these extreme conditions.