Redesigning casing programs with protection strings as liners to improve safety and cost efficiency in directional well construction
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Full Text |
Pdf
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Author |
Mahmoud Kamal, Taher Elfakharany and Ahmed Nooh
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e-ISSN |
1819-6608 |
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On Pages
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270-289
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Volume No. |
21
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Issue No. |
5
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Issue Date |
May 10, 2026
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DOI |
https://doi.org/10.59018/032637
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Keywords |
protection casing string, liner casing, casing design, directional drilling, safety improvement, non-productive time (NPT) reduction, drilling cost optimization, well integrity.
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Abstract
This study proposes the use of a protection casing string as a liner in low- and medium-pressure zones of directional wells to reduce drilling costs, minimize non-productive time (NPT), and enhance operational safety. Two directional wells were redesigned using Halliburton Landmark software to analyze casing stresses, while Microsoft Excel was employed to model costs. The conventional well design was modified to replace the traditional 9⅝″ production casing with a liner system, supported by single-stage cementing and mechanical hangers. This improved design reduced casing pipe length, eliminated the need for additional wellhead components, and avoided cold cutting operations. Pipe costs decreased by 50–60%, cement costs by 30–50%, and NPT related to the relevant operations was reduced by approximately 90%. Overall, the approach lowered well construction costs by $190,000 to $200,000 per well. Using the protection string as a liner is a technically viable, cost-effective, and safer alternative for directional wells, particularly in depleted reservoirs. This method improves drilling efficiency, reduces operational risks, and offers significant economic benefits in multi-well development scenarios.
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