![]() ![]() ![]() ![]() The results indicated the reduction of local fluid velocity and bed shear stress with an increase in the blockage level. Similar results were obtained for a concentric annulus. Results also demonstrated substantial variation in the bed shear stress in the lateral direction, which causes non-uniform bed erosion. The bed shear stress exhibited significant reduction with a decrease in the bed thickness. showed the impact of the level of annular blockage on the bed shear stress under laminar flow conditions. Similar studies were performed to analyze laminar flows in concentric and eccentric annuli.īased on the CFD analysis of eccentric annular flow, Rojas et al. Previously, CFD models for partially blocked annuli were established considering laminar flow conditions. A CFD investigation is frequently preferred approach to study the connection among relevant flow parameters (pressure loss, bed shear stress, and flow rate) in eccentric annuli. The development of solids beds makes the wellbore flow geometry complicated consequently, analytical solutions are not possible to establish when a stationary solids bed is formed. The model should account for the bed shear stress variation occurring because of bed thickness variation.Ĭommon flow parameters in the wellbore such as bed shear stress and pressure loss are affected by mudflow rate, fluid properties, and wellbore geometry (eccentricity, bed height, and diameter ratio). Therefore, an accurate bed shear stress model is required for hydraulic optimization. However, an increase in pressure due to the flow rate increase can offset the decline in frictional resistance achieved because of bed thickness reduction. If the flow rate is increased, the solids bed thickness would decrease. For an effective hole cleanup, the enhancement of bed shear stress and local fluid velocity on the bed surface is vital. Several studies have been performed to examine the flow in an annular region and develop effective hole cleaning solutions and manage wellbore pressure within the operating window. Therefore, a wellbore hydraulic study is vital in establishing a precise model to compute the pressure loss in the annulus and optimize hole cleaning. The formation of the bed restricts fluid flow and increases the pressure loss and bottom hole pressure, which needs to be maintained within the operating pressure window to prevent drilling problems.įailure in ensuring a good hole cleaning leads to several drilling issues such as formation damage, fluid loss, lost circulation, high torque and drag, or stuck pipe. The formation of the stagnant zones makes the cuttings removal process inefficient, leading to the development of stable solids beds. This eccentric wellbore geometry causes a non-uniform fluid velocity profile in the annulus creating low-velocity stagnant regions to develop. One of the major drawbacks of drilling horizontal and inclined wells is that the inclination causes wellbore eccentricity. Introduction Hydrocarbon production from horizontal and inclined wells is now a widespread practice. ![]()
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