A 3D Digital Approach to Flow Assurance

Abstract

The oil and gas industry has long perceived computational fluid dynamics (CFD) as a computationally expensive, high-end simulation method to analyzing extremely complex behavior. However, the recent increase in computational power and the democratization of CFD packages have enabled 3D modeling to become part of the regular in-house execution scope. This paper presents a range of flow assurance CFD applications and shows the impact of 3D workflows in the overall system design, the adoption of standard specifications, and fast-track project executions. As oil and gas fluid journeys from the reservoir pore space to production facilities, it faces a wide range of complex flow assurance issues related to the nature of the live production fluids (compositional changes, viscosity, compressibility), the production system environment (high and low pressures) and its interaction with hardware (erosion, flow induced vibration, scaling). One-dimensional mechanistic models are used to solve these flow hindrance issues in wells and pipelines but provide limited results in the complex geometries of subsea and subsurface equipment. In subsurface applications, a CFD workflow was used to tune near-wellbore reservoir properties based on advanced 1D and 3D thermal modeling of the completion interval. Accurate thermal modeling was then used to manage downhole flow assurance issues (e.g., asphaltenes and scale buildup). In subsea equipment, the methodology was used to fast-track project execution by using standardized equipment using project specific parameters at an early stage. CFD analyses were used to estimate the risk of erosion and flow-induced vibration in a subsea tree. The thermal aspect was not neglected because CFD conjugated heat transfer was used to detect cold spots and improve the thermal behavior of insulated equipment (trees, manifold) during normal production and shutdown. To avoid long and expensive material qualification campaigns, CFD was used to define the temperature gradient in trees and compare the design temperatures of materials against their calculated temperatures. The ability to perform advanced CFD calculations has become a true enabler in the ability to adopt standardized equipment and supplier-led specifications on subsea field development applications, thus contributing to better capital efficiency and shorter time from discovery to production. Several concrete examples from wide-ranging subsea field development projects worldwide are presented to illustrate the added value of CFD in all stages of engineering, from concept definition to project execution.