In this Case Study, AFS shares its experience in using an integrated production model (IPM) to help our client who needed to perform techno‑economic assessments during the field development planning of an asset.
The asset is in the mature North Sea basin, close to several existing host infrastructure options for tie-in along with a standalone FPSO concept. In the current “Select” stage, an optimal field development plan is to be selected by considering the techno‑economical merit of each concept. However, given there are 3 feasible hosts plus the usual route selection, line sizing, thermal insulation, artificial lift and subsea processing options, there are unsurprisingly a confounding number of choices.
A methodological yet fast and reliable approach was needed to ensure high‑quality data is available for the client’s cashflow model and commercial negotiations. Ideally, the same forecast provides clear‑cut thermal‑hydraulics to support technical flow assurance studies.
AFS developed an IPM which includes the reservoir, wells, production chokes, flowlines, riser and topsides; and as needed, downhole gas lift, subsea multiphase pump (MPP), and a subsea separator. Leveraging on advances in mathematics and computer science, the IPM is able to perform life of field production forecast coupled with rigorous thermal‑hydraulics in an efficient manner. Crucially, the IPM eliminates the need for simulation boundary between subsurface/subsea/topsides, as these interfaces may create a mismatch in quality at data handover. The result is an accurate prediction of asset performance over field life, a sound basis for cashflow modelling, right sized network and CAPEX, and an insightful projection of the operating envelope as it evolves over time.
Figure 1 shows a selection of output and analysis from this integrated approach:
– Cumulative production curves and input to economic analysis. For brevity, four concept cases are shown though in reality many more were studied encompassing sensitivity to line sizes, flowline routes, artificial lifts etc. The intuitive results facilitated the right sizing of development concept, equipment and capital budget.
– Life of field arrival temperature predictions, along with measured WAT. Taking a life of field view reveals that the temperature increases with watercut, so the wax risk is not disproportionately amplified along time. This paves the way for risk‑based, thermal or chemical wax management and unleashes opportunity for the project.
– A bird’s-eye view of the erosional velocity ratios against line sizes and field life.
Figure 1: Techno-Economic Assessment Using an Integrated Production Model
In summary, this Case Study discusses the technical challenges of field development planning and identifies a solution approach, which can be tailored according to the nature of the field and any applicable system constraint. The primary study outcomes were:
– High resolution production forecast generated in a fast and reliable manner to enable robust techno‑economic assessment
– Integrated laboratory and engineering services to turn challenges into valuable, actionable insights