A New Riserless Method Enable Us to Apply Managed Pressure Drilling in Deepwater Environments

Abstract

Managed Pressure Drilling has been proven to be a tool for extending access to previously unattainable drilling targets in many deepwater areas across the world, such as deepwater Gulf of Mexico. 21" Low-Pressure risers do not allow for application of Constant Bottom Hole Pressure (CBHP) technique by floaters. Since it is not designed to hole the pressure, it prevents setting up a closed circulation loop in our drilling system which is an essential tool for MPD.A high-pressure riser along with a surface Rotating Control Device is required to perform CBHP drilling technique. However, we know that deployment of such high pressure risers in long lengths and harsh environments has not come to be practical.An alternative drilling method from floaters at any water depth proves to be Reelwell Drilling Method (RDM). Reelwell AS, Shell, StatoilHydro, and the Research Council of Norway launched a JIP in 2005 to develop RDM, which is a riserless drilling method based on concentric drill pipe. Mud is circulated in a closed loop in this system. The pressure and flow of mud is dynamically controlled by a computer system on the return path on the surface. Many tests including the latest pilot test in March 2009 has proven that the downhole pressure can be controlled precisely and that the system fits perfectly for CBHP. Deployment of this technology by smaller floating rigs is possible with no limitation on water depth as huge and long 21" LP riser is eliminated from the system. The volume of mud is limited to bring about even more cost and rig space savings.

Study on the Mechanical Extended-Reach Limit Prediction Model of Horizontal Drilling with Dual-Channel Drillpipes

“…In field practice, a shallow horizontal trial well was completed onshore in Alberta, Canada with dual-channel drillpipes [15]. Improvements are also expected in offshore drilling performance with dual-channel drillpipes by eliminating the need for the long riser [16][17][18]. Theoretical studies were also performed on the flow behavior and well cleaning efficiency of dual-channel drilling.…”

Erosion Law of Inner Drill Pipe in Reelwell Reverse Circulation Directional Drilling

“…This new type of reverse circulation pressure control drilling technology has great potential and advantages over conventional drilling methods in the accurate control of bottom hole pressure, wellbore cleaning, drilling pressure application, large displacement drilling, ultra-deep well drilling and obstacle drilling. At the same time, because the drilling fluid circulates inside the drill pipe, the working radius and drilling depth of the drilling ship is extremely larger than conventional offshore drilling [1][2][3]. The double-drill horizontal drilling system is a closed-loop circulating flow system.…”