Dual-Drillpipe Method Shows Success in PMCD Wells With Cuttings Return

Abstract

Technology Update The Reelwell Drilling Method (RDM) is a new technology developed to solve certain drilling problems and improve the operation margin for various applications. The technology uses a specially designed dual drillpipe (DDP), shown in Fig. 1, that has two flow channels, one for the flow of drilling fluid into the well down to the bit and the other for the return flow of fluid from the bottom of the well back to the surface. Developed in Norway, the RDM has been field tested at various locations in the past several years. The technology has features for pressurized mud cap drilling (PMCD), managed pressure drilling (MPD), and extended reach drilling (ERD). The RDM enables PMCD with cuttings return MPD with a constant well pressure profile ERD with reduced torque and drag, no equivalent circulating density (ECD) in the wellbore, and no cuttings in the hole The DDP is available in 6?-in. steel and 5?-in. to 7½-in. aluminum pipe diameters. With a pressure rating of 5,000 psi, the DDP contains a concentric inner pipe with a stab-in connector and is handled in the same way as a conventional drillpipe. The RDM can be adapted to a standard drilling rig, with the following tools and arrangements: A top drive adapter—a swivel directing the fluid return through a second standpipe and mud hose An inner pipe valve—a bottomhole assembly (BHA) tool for the isolation of the drillstring during connections A flow control unit—a skid with a control valve system for flow and pressure control A rotary control device—a standard tool at the blowout preventer for MPD The RDM uses standard BHA components and drill bits, and the tools operate on reduced flow rates.