Overcoming the Unique Production Chemistry Challenges of Subsea Separation, and Subsea Boosting for the Parque das Conchas (BC-10) Development
Authors: Hera John , Gingrich R. 
Published: July 2010

The recovery of crude oil and gas from deepwater fields present significant challenges for flow assurance and production chemicals. In deepwater environments, production is often complicated by multiphase fluid flow, diverse fluid compositions and high fluid viscosities. In this paper, we describe the use of chemical knowledge, field experience and laboratory testing to develop a chemical antifoam to mitigate crude oil foaming for the unique Parque das Conchas subsea project, located in block BC-10, offshore Brazil.

The Parque das Conchas project employs subsea separators and electric submersible pumps contained within subsurface caissons. Without effective management, the potential exists for crude oil foaming to negatively impact the efficiency of subsea separation equipment and the operability of the entire production system. The challenging subsea production conditions necessitated a high performance umbilical qualified defoamer to mitigate this flow assurance issue.

Laboratory testing of Parque das Conchas crude oil under simulated separator and flow line conditions was conducted to evaluate antifoam products. Based on test results, a fluorosilicone antifoam product was selected. Preliminary field performance has proved to be excellent with behavior of the produced fluids and antifoam correlating with expectation and laboratory simulation, confirming the approach taken. The crude oil antifoam product developed for Parque das Conchas is the first in the industry that is qualified for a deepwater project utilizing both subsea separation and boosting.

Introduction

The term flow assurance refers to " the ability to economically and without interruption produce petroleum from the reservoir to the production facility?? (B. Fu, 2000). Flow assurance problems can occur, however, even with uninterrupted fluid flow as demonstrated by emulsification and foaming (L.L. Laurence, 1981). The ability to predict, monitor and prevent such problems is necessary to optimize petroleum production under all process conditions (M.K. Poindexter et al., 2001). This paper will focus on the development and deployment of a production chemical antifoam for the challenging conditions at Parque das Conchas, which represents an " industry first time?? antifoam application for subsea separation caissons.

Field Description and Flow Assurance Challenges

Parque das Conchas is a deepwater (~ 6,000 ft) development located in the Campos Basin, approximately 120 km southeast from the city of Vitoria off the coast of Brazil. Phase 1 of the development involves production from three fields: Ostra, Abalone and Arganauta B-West. Phase 2 is currently under development with planned first oil in 2013. This comprises the development of the Argonauta O-North field. Shell is the operator with a 50% working interest, in a joint venture with Petrobras (35%) and ONGC (15%). The Parque das Conchas development differentiates itself from other conventional subsea designs by its unique flow assurance characteristics including:Subsea separation and boosting systems located at Ostra fieldSubsea multi-phase pumping systems located at B-West field