Flow assurance: Managing flow dynamics and production chemistry

Abstract

Production impediments caused by either fluid dynamics and/or production-chemistry-related issues in the wellbore and flowlines have long been identified both in onshore and shallow-water environments. Historically, production impediments were managed using periodic workover operations because of the relative ease in accessing the source. In deepwater environments, these production impediments are severe owing to cooler temperatures, greater hydrostatic head, longer flowlines and, therefore, complex fluid behavior in subsea lines. Higher risks are often associated with organic and inorganic solid precipitations in the wellbore and longer flowlines. Economic well count requires mixing of well production from various sources and may lead to complex fluid compositional systems, thereby presenting many flow-assurance challenges, leading to higher capital (CAPEX) and operating expenditures (OPEX). These fluid dynamics and hydrocarbon solids formation and deposition adversely affecting flow assurance in deepwater production systems are key risk factors in assessing deepwater developments. To reduce this risk, a systematic approach to defining and understanding the thermodynamic factors impacting flow assurance is required. The development of experimental techniques to provide this information is a current focus of attention in the reservoir-fluid phase-behavior community.In this review paper, we discuss three field examples that demonstrate the importance of integrated methods in assessing risks of flow impediments. The first example deals with a holistic approach to handling various aspects of flow assurance in gas/condensate reservoirs. The second example combines the steady-state fluid flow and heat-transfer characteristics along with asphaltene thermodynamic considerations and, therefore, assesses the risk of development from a holistic perspective. Finally, the third example discusses the importance of transient heat-transfer and fluid-flow modeling coupled with wax-gelling characteristics, enabling a cost-effective operating solution in a deepwater subsea environment.