Evaluation and application of calcite scale inhibitor in an offshore pH stabilised MEG system—an Australian first
Farrell Backus A , Evan Harvey A and Mike Gunn BA Nalco Champion
B Santos Ltd
The APPEA Journal 55(1) 247-264 https://doi.org/10.1071/AJ14019
Published: 2015
Abstract
Calcite scale mitigation in pH stabilised MEG systems is a growing concern for the industry as a number of systems are planned for upcoming Australian gas projects.
Issues are insignificant at first gas when water of condensation is present. When formation water production occurs, scale management becomes a critical component of project feasibility. A closed loop pH stabilised MEG regeneration system located in the Otway Basin faced these challenges. Severe calcite scaling in a subsea well, which led to choke failure and MEG system fouling, was successfully controlled by the application of a specific polymeric scale inhibitor.
The operating nature of a pH stabilised closed loop MEG system eliminates conventional scale inhibitor chemistries. Customised polymer chemistries were selected for review predominately due to their ability to persist in a variety of harsh conditions, including the MEG regeneration process.
Technical qualification to validate scale inhibitor functionality was completed using protracted compatibility testing and Dynamic Scale Loop assessment. Evaluation of inhibitor performance and behaviour was accomplished using customised monitoring processes focusing on scale inhibitor detection, identifying measurement interferences, and interaction with precipitated solids.
Field implementation provided excellent results with the inhibitor averting further severe scaling issues, resulting in minimal production system disruption. Fouling of the MEG regeneration system in particular has been minimised, resulting in a reduced frequency and length of cleaning cycles.
This peer-reviewed paper will detail the evaluation, application and monitoring fundamentals when introducing scale inhibitors into pH stabilised MEG systems.
Farrell Backus has more than 18 years of combined experience in oilfield chemistry and operations. His career started in Canada, studying steam engineering, gas processing and field operations. Operational experience opened opportunities for diversification into oilfield chemistry with Champion Technologies (now Nalco Champion). Farrell’s experience extends across account manager, enhanced business coordinator and key account management positions in both Canada and Australia. Farrell presently holds the position of District Technical Manager, and supports all technical requirements within Australasia from Perth, WA. |
Evan Harvey is the South Australian Account Manager for Nalco Champion, an Ecolab Company. He received his BSc from Curtin University in Perth, WA, and has worked for BHP Billiton and the Australasian Lubricant Manufacturing Company. After starting with Nalco Champion (previously Champion Technologies) in 2007, Evan soon advanced into account management, being responsible for several offshore FPSOs and providing troubleshooting support. In 2010 he relocated to Adelaide to manage business within the Cooper Basin. |
Mike Gunn has 37 years of professional experience in the oil and gas industry. His experience spans assets in the North Sea, Middle East and Southeast Asia. During this period he has fulfilled a number of laboratory, operations and consultancy roles. Mike now holds the position of Staff Chemist with Santos Ltd, and is based in Adelaide, SA, where he is responsible for the development of treatment and testing programmes across the company’s assets. |
