Abstract
Sand transport in horizontal wells with multiphase flow is a complex phenomenon due to the horizontal well trajectory's having strong impact on multiphase flow and sand transport behaviors. Most of the previously published studies on sand transport centered around pipeline flow applications and less so on sand transport in wells, and particularly, on understanding the effects of well trajectory and the associated sand transport capacity for different well trajectories. Therefore, this study presents qualitative comparison between different well trajectories and their impact on sand transport. This is an important aspect of optimizing the well trajectory where co-sand production strategy is selected.
Five different well trajectories have been selected in this study, which include 90-degree horizontal, toe-up, toe-down, sump and hump trajectories. Multiphase transient simulation has been carried out for each case to evaluate the effect of well trajectories on sand transport in multiphase flow, and the sand deposition profiles including moving bed, stationary bed and suspended particles associated with each horizontal well trajectory.
The study results reveal that 90-degree horizontal, sump or hump well trajectories always have higher capacity to transport sand compared to toe-up and toe-down trajectories. Thus, it helps in delaying the plugging of the horizontal section, sustain well production and reduce sand cleanout requirements. In addition, the toe-up trajectory has higher capacity for sand transport than the toe-down trajectory. Sensitivity analysis has been performed to evaluate the effect of sand particle size, fraction, water cut and GOR on the sand transport capacity for each case of different trajectories. The overall observations showed that as the sand particle size and fraction increases, the sand deposition tendency to form stationary bed increases due to the increase of gravity force. On the other hand, as the water cut, and gas oil ratio increases, the sand deposition tendency to form stationary bed decreases, due to the weak lift force to carry the particles along as the liquid viscosity is low. It is noted however that that the magnitude of effect for each parameter on the sand capacity limits for sand transport is different.
This study presents a novel approach to improve the horizontal well planning where co-sand production strategy is selected. This would help in achieving sustainable production and reducing the number of cleaning operations required during the well life cycle.
