Smart Drilling with ELECTRIC DRILLSTRING™

Abstract

Abstract This paper will present the results to date of a project to develop an electric drillstring, together with some ideas and visions of how this technology could make a step-change in well construction. The electric drillstring should enable electric power to be transmitted through the drill pipe, while simultaneously multiplexing data back to surface from the downhole drilling system. This could allow a range of improvements to the drilling process, that we shall call "smart drilling", which should result in reduced drilling costs and optimized well placement for maximum productivity. The project has followed the normal phases in any technology development, but only the initial two phases of feasibility and benefit assessment have been completed. The initial phase was to learn what had been done in the past to transmit electrical power and telemetry in a drillstring, identify the key problems and try to come up with some novel solutions incorporating technical improvements from both within and outside the drilling industry. The key benefits of the new system were identified, together with a range of potential applications that could be available in both the short and longer term. The heart of the system is a reliable electrical connector integral with a premium drill pipe thread that will behave like a normal tool joint during operation. This is combined with mid-body conductors, in this case sandwiched between a metal inner layer and the drill pipe body. The development of the first two prototypes, which are on the route map to the initial field test, will be discussed. Smart drilling via an electric drillstring can offer a wide range of possible advantages over conventional drilling operations, which could include:Reduced drilling costs from the optimization of the drilling process by control of weight on bit using downhole traction or thrusters, and maintaining bit speed independent of flow rate.Reduced wellbore stability problems due to both reduced ECD via reverse circulation and knowledge of the pressure conditions from sensors distributed over the length of the well.Reduced costs by replacing wireline logging with real-time LWD systems.Reduced stuck-pipe in ERD-type wells from traction tools distributed along the drillstring.Improved well productivity from improved geosteering via immediate data feedback from the high quality telemetry path.The development of Seismic-while-drilling (SWD) utilizing downhole sources and recievers.The possible development of new sensors that take advantage of the excess power available downhole. These concepts will be briefly discussed in the paper together with the results of an initial benefit assessment. Introduction The drilling industry has accomplished some quite extraordinary achievements with very limited telemetry from downhole tools powered either by batteries or turbines. This is especially so when compared with the large increases in data telemetry rates that have occurred in other industries in the last few years. It is our contention that, with a higher data telemetry rate and the ability to power and control a range of downhole drilling tools, this so-called "smart drilling" will enable a step-change in the way wells are drilled and how the drilling process is controlled.