Application of Euler-Bernoulli finite element methods for torque and drag model verification

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Date

2022-12-02

Authors

Elyas, Odai Alaa

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Abstract

As the industry extends its search for hydrocarbons in remote locations, efficient extended reach drilling operations become crucial to reaching subsurface targets. This starts

with enhanced simulation and monitoring of real time data measurements. Torque and drag are two of the most important parameters that are monitored continuously throughout any oil and gas drilling operations. Where torque is defined as the force of rotation between the drill pipe and the wellbore wall and drag is defined as the force required to push or pull the drill pipe through the wellbore and formations. The two parameters are often used as indicators for downhole conditions and must be maintained within certain ranges to ensure successful drilling to the targeted depths and running in hole the required completion equipment. Prior to any drilling operation, an estimate of both torque and drag are calculated based on the known drilling fluid properties, and formation parameters. Which is then used as an indicator of drilling issues such as wellbore collapse, cuttings accumulation, and change in drilling fluid properties. Several analytical models are utilized for torque and drag calculation. The first, and widely used approach is the soft string model which assumes the drill pipe acts as soft string taking the shape of the wellbore. This assumption neglects additional forces that cause the drill pipe to bend in deviated locations, which often results in underestimating torque and drag measurements in complex well designs. To address this, a stiff string model was implemented which considers the pipe’s bending stiffness and its effects on torque and drag calculations. Additionally, finite elements analysis (FEA) has been implemented to validate torque and drag calculations throughout the industry. However, the application of FEA often includes mesh generations which creates a 3D model of the drill pipe and subdivides the object into smaller domains to perform the calculations across the entire volume. This approach typically requires special software or large computational power to perform the calculations in a timely manner for real time monitoring applications. This thesis presents an approach to FEA that utilizes the Euler-Bernoulli beam equations, with the addition of an axial forces component to address both axial and transverse forces and deformations. The outcome of this thesis provides an accurate representation of torque and drag calculations, performed efficiently which could be used for planning, and real time monitoring during drilling operations.

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