Approach Redefines Ideal Project Scope and Facilities Size for Field Development
Authors: Wilson Adam 
Published: September 2017

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 182269, “An Investigation of the Optimal Definition of Project Scope, Facilities Sizing, and Design Life for Truly Sustainable Deepwater Field Development: Technical Aspects and Economic Considerations,” by Francesco Beltrami, SPE, Energo Engineering, and Andrew Gifford, Shiladitya Basu, and Andre Berardi, Granherne, prepared for the 2016 SPE Asia Pacific Oil and Gas Conference and Exhibition, Perth, Australia, 25–27 October. The paper has not been peer reviewed.

This paper investigates how decisions made through reservoir evaluation and drilling-and-completion planning affect the design of subsea production systems and, in turn, the design of production hosts. Practical alternatives are explored by challenging the current approach to project framing and definition. Rethinking the requirements of deepwater-field development will help define the proper size of the subsea and surface facilities, the optimal design life, and the possible need for staged developments.

Introduction

During the past 2 years, the offshore industry has looked with increasing interest, and undeniable concern, to practical and effective ways to reduce the capital expenditure (Capex) of deepwater projects.

Looking at the three main components of a deepwater-field production infrastructure—host, subsea production system including export, and subsea wells—the host offers the greatest opportunity for Capex reduction. Cost reduction is achievable by optimizing the subsea production system and by adopting new technologies and practices for the construction of subsea wells, but a more relevant cost reduction is possible in principle by properly sizing the host. This, in turn, requires rethinking the way deepwater projects are sanctioned and contracts between local governments and operators are negotiated.

The fact that over capacity exists in offshore hosts is well-documented. Less evident, but still convincing, is the fact that several subsea tiebacks, successfully con ducted over the past decades across the world, were possible only because a host already existed nearby that had available process or storage capacity.

Sometimes, overdesigning a host may not be avoidable because of the limited time the operator has to develop and produce the offshore fields. If contracts were structured in a different way and the operators had the chance to operate the offshore field for a longer period, it might have been possible to use smaller hosts and subsea production systems, thus reducing both Capex and operational expenditure (Opex).

Project Framing and Host Sizing

Overview. Before a deepwater project starts its life cycle, and then periodically during the cycle, reservoir engineers and drilling-and-completion engineers study and determine the optimal way hydrocarbons can be recovered. Subsequently, wells and completions are designed to achieve this goal. The decisions made within these disciplines become part of the basis-of-design document that is the starting point for other disciplines tasked with the design of the host and the subsea production system.