Drilling and Completing Cascade and Chinook Wells: A Design and Execution Case History

Abstract

Abstract The paper is based on work performed during the design, implementation and operation of the Cascade and Chinook Field Development Project in ultra-deep water in the Gulf of Mexico. It describes the basis of design for the drilling and completion of the wells, new technology selection criteria, risk and cost mitigation plans applied during the well operations, ultra-high pressure perforating of an interval longer than 700 ft, application of the first Single-Trip Multi-Zone Frac Pack System (3 zones) in wells deeper than 27,000 ft MD, and the unique fracturing design approach used to deliver multiple fractures across 1200 ft of reservoir thickness. This case history paper will describe the pre-qualification work done with all critical systems and details of the well construction operations during the drilling and completion of the wells. The information provided will be useful for Operators to identify the technologies that are most suited for application in deep wells. It will also serve as a starting point for the design and construction of wells for other operators developing projects in the Lower Tertiary play, which is a key exploratory frontier in the U.S. Gulf of Mexico (USGoM). More than 12 discoveries have been made in the Lower Tertiary, with potential recoverable reserves of several billion barrels of oil. The results and conclusions presented in this paper are related to the feasibility and benefits of using new technology and prototype equipment in the Lower Tertiary environment. Field data from critical well operations will be included. The technical contributions of the work presented in this paper are as follows: pushing the technical limits of Single-Trip Multi-Zone frac-pack systems to depths over 27,000 ft using high (>30 bpm) fracture rates and high strength proppants; enhancing the knowledge gained from ultra-high pressure (>20,000 psi) tubing conveyed perforating systems; and presenting a well design criteria suitable for high drawdown (>12,000 psi) production operations. Introduction The Cascade and Chinook (C&C) development plan in the Gulf of Mexico is one of the most technologically challenging and complex projects implemented by Petrobras. This project uses the first Floating Production Storage and Offloading vessel (FPSO) in operation in U.S. waters, at a water depth of 8200 ft. The C&C subsea infrastructure considers the use of subsea manifolds, rigid flowlines, pipe-in-pipe pipelines, and Free Standing Hybrid Risers (FSHR). Details about the subsea infrastructure and the FPSO are discussed in greater detail by Porciuncula et al. (2010) and Corte et al. (2010).