Accessing Technical Depth Needed To Conquer the Abyss
Authors: Langley Diane 
Published: February 2015

Professionals convening at the Offshore Technology Conference (OTC) 2005 2–5 May at the Reliant Center in Houston will be presented with a roster of technical presentations representative of a spectrum of challenges that confront the energy sector in its drive to go deeper. Industry specialists on such diverse topics as the progressive evolution of electrical submersible pumps (ESPs) in Brazil’s heavy-oil environment, ballistic mitigation on Thunder Horse, spectacular developments in deepwater pipe-lay systems, field experience with multiphase boosting systems, and refined laser technology to locate riser annulus breaches will share firsthand knowledge of steps now being taken to conquer the abyss. The OTC Program Committee selected some of the outstanding papers to be presented at the conference.

Pioneering ESPs in Deepwater

The continuous challenge to advance submarine exploration into ever-deeper water has stretched the learning curve in a number of technology areas, including ESP systems. Petrobras’ offshore Campos and Espirito Santo basins, with heavy-oil (ranging from 14 to 19º API) reservoirs at water depths from 400 to 3000 m, have provided valuable experience in both ESP-technology development and application. The mature fields in the Campos basin continue to provide the laboratory for testing new ESP technologies without jeopardizing expensive deepwater operations.

“New technological levels have been and continue to be addressed in the application of ESP systems in ultradeep water,” said Pellegrini Ribeiro, lead author of OTC 17415 on the use of subsea ESPs in Brazil. “The outcome of our research and development efforts translates to a savings of hundreds of millions of dollars in that rather than building an expensive platform, several ESP systems can be installed to pump oil from distant wells to a nearer facility, such as an existing platform or process plant that is operating below its capacity.”

Having pioneered the use of a subsea ESP with prototype testing on the RJS-477 well at 1106 m during 1998–2001, Petrobras has included research and development on ESP specifications in its PROCAP 3000. The goal of this development program is to create methods and equipment to produce oil in ultradeep waters. As part of the PROCAP 3000, several projects have been set for developing ESP assembly systems that are capable of pumping heavy oil, containing 50% free gas, at a high flow rate.

Why the interest in ESP systems? The long production lines and low oil temperatures inherent with subsea satellite wells create limitations for natural-flow and gas lift methods. These limitations point out the need to develop an alternative method, such as the ESP method that is not adversely affected by distance from the well to the host platform. Challenges to ESP-equipment development have centered on increasing nonfailure operation time and increasing ESP capacity to pump heavy oil containing large quantities of free gas. The three major issues of concern are reliability, deepwater qualifications, and well location at a long distance from a floating production, storage, and offloading (FPSO) facility. High-temperature, high-horsepower motors have been specifically designed for ESP applications involving deeper wells, high flow rates, and difficult environments. Also, a new pump design needed to be achieved for producing oil containing as much as 50% free gas.