Technology Focus: Offshore Production and Flow Assurance (November 2018)
Authors: Dino Galen 
Published: October 2018

Technology Focus

Production-design, engineering, operations, and maintenance concerns have represented some of the more interesting and challenging issues with which I have dealt over more than 20 years of experiences around the world in offshore production facilities as a major operator; manufacturer; and engineering, procurement, and construction contractor. While gas-hydrate handling typically dominates thermohydraulic design, the mitigation of wax, erosion, asphaltenes, corrosion, and salt deposition, along with solids handling; slugging; and elimination/ minimization of pipeline, tubing, and surface choke failures are all challenging issues that demand attention and considerable technical effort. 

The deposition of paraffin (interchangeable with wax) in pipelines has gained importance in offshore production design, engineering, and operations. Development of reliable wax-deposition mathematical models based on specially designed flow-loop experiments is worthy of investigation as an available mitigation option. Developing erosion-prediction models for fine particles in multiphase flow is another option to address offshore production assurance. Also, addressing these challenges requires thorough technical investigation and development of offshore pipeline failures. The three papers presented here discuss slightly different issues and approaches to production continuity and oil/gas fluid-production assurance. All three have been defined by mathematical modeling and verified with actual field confirmation and use.

Wax deposition is a phenomenon present in oil-production systems mainly in deep water. Given the relevance of this issue in new-fields development and the absence of a theory able to explain its evolution and characteristics, the production limitation caused by this phenomenon is one of the main issues in offshore production. Because the flow regime in production lines can vary from laminar to turbulent, the influence of the Reynolds number in the deposition phenomena is investigated and modeled in paper OTC 28053. The model combines an enthalpy/porosity approach with a kinetic energy/specific dissipation turbulence model. The main behaviors observed with respect to the shape of the paraffin deposit for turbulent regimes were verified with the proposed model and corroborated by the thermal, velocity, and turbulence profiles presented.  

Pipeline production systems often experience complex multiphase flow and entrained fine particles. The erosion from solid fine particles presents one of the larger threats to oil and gas offshore production. Paper OTC 28360 investigates the erosional effect caused by fine particles in annular flow regime using a multiphase computational fluids dynamics (CFD) approach. The integration of a multiphase-fluid-flow model and erosion calculation using a multiphase CFD approach improved the accuracy of erosion prediction.    

Paper SPE 188717 presents a failure-root-cause analysis for offshore pipelines. The study objectives were to evaluate potential causes of failures of several pipelines operating in shallow waters and develop an analysis/program to identify the root cause of failure, perform an analysis to confirm the causes of failures, assess remedial measures to find the most suitable option, recommend those remedial measures, and then perform high-level engineering to confirm suitability of the chosen option in accordance with recommended practices.

Offshore production assurance continues to drive new production technology applications and approaches. The three papers highlighted here focus on developing analytical tools and performing root-cause analyses while providing safe, cost-effective, and reliable operations. I hope you find them as interesting as I did; I much appreciate this opportunity to disseminate these new technology options to you. In addition, I invite you to join the Flow Assurance Technical Section to learn more on different topics.

Recommended additional reading at OnePetro: www.onepetro.org.

OTC 28155 Stability Solver for Offshore Oil Flows by Ivanilto Andreolli, Petrobras, et al.

OTC 28548 A Pragmatic Approach to Corrosion Inhibition of Offshore Pipelines Transporting Produced Hydrocarbons by Robert Horan Nuttall, Petronas, et al.

OTC 28885 Risk-Based, Statistical Approach to Assessment of Corrosion Anomalies in Pipelines by Derek Scales, Atteris, et al.