Beyond Plug Flow: Realistic Fluid Displacement Modelling for Sand Control Success

Abstract Idealized plug flow is rarely experienced when displacing fluids through a wellbore. The challenge to understand such displacements becomes especially critical during sand control operations, where significant mixing between fluids can compromise treatment success. Effective displacement, defined as the efficient replacement of one fluid with another, is essential for both well productivity and completion reliability. Achieving this, however, requires careful planning and a deep understanding of fluid flow regimes, which is complicated further in deviated and horizontal wells, where gravitational segregation and channeling significantly degrade displacement efficiency. This paper presents a novel model which enables a practical, predictive approach to optimizing fluid displacement and mixing in sand control treatments. Unlike traditional hydraulic software that assumes piston-like flow between fluids or relies on proprietary data, the model introduced here uses a commercially available, accessible and independent simulation platform that directly supports the flow paths used in sand control operations. It incorporates key physical parameters including fluid density and rheology contrasts, flow regimes, wellbore deviation, and completion geometry to realistically simulate the transport dynamics of multiple fluids in practical time frames. Validated against field cases, the simulator reliably captures complex fluid dynamics under a variety of operational conditions. It reveals that the fluids reaching the perforations or open hole often differ significantly from designed schedules due to mixing. This predictive insight enables proactive optimization of fluid properties, pumping rates, or completion configurations to mitigate risks. This is illustrated with several examples which show strong correlation between modelled predictions and observed field performance, confirming the accuracy and robustness of the approach. By enabling better control of fluid placement and minimizing unintended outcomes, this model contributes to more reliable, cost-effective, and environmentally conscious sand control treatments. Its implementation can lead to more effective wellbore cleanup, reduced non-productive time, and improved overall completion outcomes in sand control treatments.