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Numerical Analysis and Opitimization of Barrel-Slips Used in Downhole Equipment

Heydarifard, Sina | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57595 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Arghavani Hadi, Jamal
  7. Abstract:
  8. Oil and gas extraction has long been considered one of the world’s major industries, with the economies of many countries, particularly Iran, heavily dependent on these resources. As the complexity of operations increases due to deeper wells and more challenging extraction conditions, we are witnessing continuous technological advancements in this field. Innovative tools are being designed and utilized daily to support and develop these industries. Downhole equipment typically has a cylindrical shape and must be positioned at specific depths to perform their respective functions. Obviously, these tools must withstand significant axial loads and weight, especially as drilling depth increases. Therefore, securing this equipment in place becomes crucial. One such tool that performs this function is the slip with tooth, which holds to the wellbore wall like a brake pad and transfers axial loads to the wellbore wall. Barrel slips, a type of integrated, reversible slip, offer the best performance and are increasingly being used. This research aims to numerically simulate, design, and optimize this type of slip. Initially, the study examines various types of slips and the advantages of the barrel-type slip over others. An initial model with geometry based on data from standard tables and existing references is proposed. Subsequent finite element analyses begin with the simplest two-dimensional problems, disregarding some system components like teeth and casing, and ultimately, the complete problem is examined using symmetry to reduce computations. Alongside finite element analysis, manual calculations are performed to validate the simulation results. Finally, a reliable model for further analysis and optimization is presented. Many parameters in the slip geometry can be optimized, but this research focuses on the most critical parameters: the length-to-outer-diameter ratio and the wedge angle. Four and three cases are considered for each parameter, respectively; and the optimal case, with a length-to-diameter ratio of 2 and a wedge angle of 20 degrees, is selected based on maximum penetration depth and minimum stress during slip installation. Additionally, the reason for choosing a triple conical surface behind the slip, instead of double or single, is explained through simulation and comparison. Finally, installation loads and differential pressure are applied on the model for the selected geometry, examining the relationship between installation pressure, tooth penetration depth, and tolerable differential pressure. It is found that with an installation pressure of 1 ksi, the average penetration depth is 0.15 mm, successfully withstanding a differential pressure of 10 ksi, which is acceptable in the industry with a safety factor of 2. The retrievability test of the slip is also successfully performed, confirming the proper operation of the slip
  9. Keywords:
  10. Oil and Gas Industry ; Supporting Pad ; Anchoring ; Downhole Equipment ; Barrel Slip ; Optimization ; Simulation

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