Hole Cleaning, Torque Management Lead to Longest Extended-Reach Well in Brazil
Authors: Wilson Adam 
Published: May 2018

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper OTC 28091, “The Longest Horizontal Section Ever Drilled in an Extended-Reach Well in Brazil,” by Rafael Kenupp, Affonso Lourenço, Stian Soltvedt, and Ian Thomson, Baker Hughes, a GE company, and Grazielli Simoes, Daniela L. Morosov, and Raquel Andrade, Statoil, prepared for the 2017 Offshore Technology Conference Brasil, Rio de Janeiro, 24–26 October. The paper has not been peer reviewed. Copyright 2017 Offshore Technology Conference. Reproduced by permission.

The Peregrino project, located in the post-salt zone of the Campos Basin, presents immense challenges for drilling extended-reach wells. This paper shares challenges imposed by the well profile and downhole environment on the design and execution phases. Information is included about the solutions used that led to reaching the target depth as planned, including the well-planning methodology, bottomhole-assembly (BHA) design, drill-bit selection, data monitoring, and procedures for maximizing the transfer of power downhole and minimizing rock-cutting energy.

Introduction

The Peregrino oil field is in the BM-C-7 area of the Campos Basin. Of 47 wells drilled from two fixed platforms in the field (Peregrino A and B), 20 were from Peregrino A, where the longest horizontal sections have been drilled. The average horizontal length was 1419 m, and the operator is pushing the technical limits to extend the overall lateral stepout, increase reservoir lengths, and maximize hydrocarbon exposure.

Drilling horizontal sections beyond the field average length has several additional challenges including mud quality along the sections, high friction factors, and surface-equipment operational limits. For extended-reach wells, hole-cleaning efficiency and proper torque management have been shown to be key factors for flawless execution.

Proposed Approach

Considering the typical well setup in off-shore Brazil, Well A-27 had a considerable total length. The planned length of the well was 8400-m measured depth (MD), with a possible extension to 8740-m MD. The landing of a 9⅝-in.-casing shoe was planned to be at 6520-m MD with approximately 82° of inclination, and the 8½-in.-section lateral displacement was to start at 5673 m from the wellhead (Fig. 1).

With a possible horizontal section of 2220 m, a rotary-steerable system was to be used, with the addition of a drilling dynamics sub and a modular motor, to reduce the demanded weight on bit (WOB) and surface rate of revolution while maintaining sufficient energy at the bit. Management of torque and equivalent circulating density (ECD) would be helped by the use of 4-in. drill-pipe, which would also provide lower torque values with less cross-sectional area. The final measure required to reduce overall friction along the horizontal well path was to add lubricant to the drilling fluid to reduce metal-to-metal friction at the drillpipe/casing interaction. Lubricant was also to be added while drilling, with the idea that drops of lubricant deposited into the mudcake would help reduce friction when drill-pipe tool joints pass through.