ABSTRACT

This paper presents a case study on the application of Computational Fluid Dynamics (CFD) to assess the capacity of installed equipment to withstand a 25% production increase, allowing for production targets to be met ahead of schedule.

Erosion predictions in the tree during this increased production period was performed based on industry-standard guidelines for sand management. The 3-D model consisted of the fluid domain, including the choke and the downstream flowspool. The erosion rates and the hot spot locations in the 3-D model were in good agreement with the 1-D model and thus validated the approach.

Regarding FIV, the 3-D analysis relied on modeling dynamic fluid pressure loading on the SPS using CFD and the structural response of the hardware using a Finite Element Analysis (FEA) approach with a one-way coupling. The results of the study showed an acceptable fatigue life calculation and enabled production increase above the rated design capacity of the equipment.

The ability to perform advanced CFD calculations has become a true enabler in the adoption of standardized equipment and supplier-led specifications in subsea field development applications, thus contributing to better capital efficiency and shorter time from discovery to first gas. This paper details the benefits of this innovative approach and how it enabled the ramp-up of subsea gas wells to a production rate 25% higher than its maximum design rate.

INTRODUCTION

For decades, subsea equipments were designed for project specifications but with the increasing cost of subsea developments, standardization became key to lower the projects breakeven costs. Standardization presents some challenges when standard equipment has to be used at their design limits throughout the life of the field. This work presents an example of the use of a Subsea tree at a higher flowrate due to some more productive wells.

The first flow assurance challenge to cope with when the equipment is exposed to a higher flow rate is solid particle erosion. Even if the initial design considered comfortable margins in the erosion calculations, a 25% production increase will have to be checked against the installed material properties to prevent equipment failure. The second integrity risk caused by increased flow thru the equipment is flow induced vibration caused by high velocities in the equipment piping.

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