First Three-Zone Intelligent Completion in Brazilian Presalt: Challenges and Lessons
Authors: Wilson Adam 
Published: April 2018

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper OTC 28136, “First Three-Zone Intelligent Completion in the Brazilian Presalt: Design Considerations, Challenges, and Lessons Learned,” by Filipe Del Vecchio, Potiani Maciel, Francisco Salom, José Chagas, and Antonio Ortiz, Baker Hughes, a GE Company, 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 The paper has not been peer reviewed.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.

Since the first intelligent completion was installed 20 years ago, the systems have become increasingly complex in order to reach productivity and optimization goals, allowing real-time independent monitoring and management of each zone in the well. Accompanying the search for greater system efficiency is the goal of reliability assurance. This paper presents the complexity and challenges of planning and installing the first intelligent completion in a subsea well with three producing zones in the Brazilian presalt.

Introduction

Below water depths greater than 7,200 ft, below salt layers up to 6,500 ft thick, and at true vertical depths (TVDs) of approximately 18,000 ft lie the presalt fields. The distance from shore (as much as 300 km), high carbon dioxide and hydrogen sulfide concentrations, high temperatures (sometimes greater than 100°C), and the existence of multiple intervals with different porosities all add to the challenges of producing from the presalt successfully.

Through the installation of permanent downhole gauges (PDGs), intelligent completion allows real-time monitoring of downhole parameters such as pressure and temperature, providing a better understanding of what is happening at any given time. Hydraulically actuated flow-control valves give the operators the ability to access each interval with the touch of a button, greatly improving reaction time and reducing the need for costly interventions. Furthermore, valves with adjustable choke settings increase ultimate recovery from the reservoir by fine tuning the production/injection of each individual zone. Chemicals can be injected to ensure productivity and avoid potential problems to production such as scale and asphaltene buildup.

Equipment Design and Configuration

Flat-pack (FP) and control-line protectors (clamps) were designed to ensure maximum flexibility, allowing for wells to be completed with one, two, or three zones without the need for additional equipment.

The splice subs also were designed with flexibility in mind. The lower the splice sub is positioned, the fewer the slots that are necessary. However, by supplying all of the subs with the same number of slots, the same slot sizes, and the same slot positioning, the equipment could be used in any type of well layout and inventory management was greatly improved.

The design of the pressure and temperature gauges and their carriers was also optimized. Instead of the PDG dictating whether the data are acquired from the tubing or the annulus, the mandrels do that. This was made possible by having two different configurations for the area where the gauge is mounted to the carrier. The tubing mandrel has a through hole allowing fluid from the inside of the string to contact the gauge’s inlet port, while the annulus mandrel has a blank interface with cross-shaped slots through which annulus fluids enter the sensor’s inlet.