Abstract

This paper describes the design and use of a subsea pumping system that allows improved construction of top-hole sections on offshore, jack up-drilled wells. This system has now been used for the first time offshore Brazil with positive results.

This subsea pumping system - the RMR® (Riserless Mud Recovery) system - has been used extensively in other areas of the world, primarily on floater-drilled wells (Stave et al., 2005; Smith et al., 2010; Cohen et al., 2010). This previous RMR experience coupled with detailed discussions with a Major Operator in Brasil resulted in this modified design for use on jack up-drilled wells, offshore Brasil.

The Major Operator has a number of wells to drill in shallow waters offshore Brasil and needs a system that provides for minimal discharge of cuttings and drilling fluids to the ocean environment during drilling and installation of the conductor string, and that also enables better management of well bore pressures when drilling the next hole section, inside the conductor string.

This new version of the RMR system has now been deployed offshore Brasil. The system collected drilling fluids from the top hole section and pumped them back to the rig successfully, thus reducing the amount of cuttings and drilling fluids released into the natural ocean environment. The system was then used, after installation of the conductor string, to provide dual gradient drilling of the next hole section (for surface casing), resulting in improved penetration rates and well bore stability below the conductor shoe.

The RMR system used is described in this paper as well as the operational experiences realized on the first two wells and the improvements being made to prepare the RMR system and techniques for additional wells.

Introduction

Use of the RMR subsea pumping system is now well-established, particularly for floater-drilled wells, in several parts of the world, namely; Norway, UK, Caspian and Australia. Although well parameters, rig configurations and water depths differ, the typical RMR system used across these operating regions is shown in Figure 1.

This content is only available via PDF.
You can access this article if you purchase or spend a download.