Extended Reach Drilling - new solution with a unique potential

Abstract

Abstract The Reelwell Drilling Method (RDM) is a new drilling method, developed and qualified for commercial use during recent years. RDM is a multi-purpose drilling method with a unique flow arrangement. RDM is based on using a conventional drill string combined with an inner string to form a dual conduit drill string. This arrangement allows the return fluid, containing drill cuttings from the bottom of the well, to be transported back through the inside of the drill string. RDM has the potential to increase the envelope for Extended Reach Drilling (ERD) for several reasons: – Torque and Drag reduction, due to use of a flotation technique of the drill string. – Elimination of the dynamic Equivalent Circulating Density (ECD) gradient, since the ECD is screened from the formation. – Optional Hydraulic Weight On Bit (WOB), due to a piston type arrangement at the drill string. The following presents a case study for an ultra ERD RDM application. In this case, the RDM arrangement involves the use of a special dual conduit aluminium drill string and the use of two different density fluids in the well during drilling. A calculation example of a fully buoyant drill string is also presented. This situation indicates that the well can be drilled with very high operational margins on the equipment and at the same time, the wear will be very low. The simulations indicate that the extreme ERD well of 15.8 km depth can be drilled with good margins, mainly due to flotation of the drill string. It is shown that the well can be cased and lined, using conventional flotation techniques in combination with RDM.