Title: Hydraulic Behaviour of Annular Pressure Loss and Circulating Pressure in Extended Reach Wells: A Simulation-Based Study
Authors: Eniye Oguta, Isaac Eze Ihua-Maduenyi, Kefas Odofori
Volume: 10
Issue: 4
Pages: 29-39
Publication Date: 2026/04/28
Abstract:
This study presents a comprehensive simulation analysis of the behavior of annular hydraulic systems in Extended Reach Wells (ERWs) using the Wellplan software package, with particular emphasis on annular pressure loss and the effects of circulating pressure under various drilling parameters. Because the fluid dynamics in ERWs are highly complex due to the long lateral sections of the wellbore, the simulation analysis investigated the hydraulic system's sensitivity to changes in mud weight, pump rate, rate of penetration (ROP), and cuttings density. The results show that annular pressure loss is inversely proportional to mud weight. Increasing the mud weight from 10 ppg to 10.8 ppg reduces the pressure loss from 2135.2 psi to 2117.08 psi. This indicates a lower average velocity through the system due to the damping effects of the fluid mass. However, the circulating pressure increases from 7285.08 psi to 7693.85 psi because of the linear increase in mud weight. The effect of pump rate exhibits non-monotonic behavior. Specifically, annular circulating pressure decreases from 7846.93 psi to 6201.6 psi as pump rate increases from 200 gal/min to 300 gal/min, but then the trend reverses when pump rate increases to 400 gal/min. This suggests the existence of a threshold beyond which the combined effects of inertia and frictional resistance become dominant. An increase in ROP from 20 ft/hr to 50 ft/hr produces only a marginal increase of 0.02% in annular pressure loss and a 0.15% increase in annular circulating pressure. In contrast, increasing cuttings density from 2.1 sg to 2.18 sg results in a slight decrease in pressure loss and a moderate 0.22% increase in circulating pressure, implying a secondary effect of cuttings-bed loading on overall pressure behavior. Overall, this study highlights the relative importance of mud weight and pump rate as the most critical controllable factors affecting downhole pressure profiles in ERWs.