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Stresses at the Bottom of a Borehole and its Effect on Wellbore Stability

Bahrami, Babak | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47527 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Goodarznia, Iraj
  7. Abstract:
  8. Instability means that when wellbore is out of circle due to any reasons in which it may be associate with fracture or falling of wellbore wall. Wellbore instability problem in production and exploration wells cause high costs over than 100 million dollars in all over the world in which these costs can be increased to 1 billion dollars so, necessary forecasts for preventing of instability is essential. Up to now, a lot of methods are suggested for investigation of wellbore instability, but in this study, analytical investigation with the help of triaxial tension is considered. Failure criterion and rock behavioral model are two important factors in wellbore stability modeling. In this study, 15 failure criteria are compared according to data of 14 different rock samples and modified lead criterion is known as the most accurate relation, finally. By merging failure criterion with around well stresses, a new relation for forecasting of the minimum mud weight for preventing from falling of wellbore wall is obtained. Real data of two wells in Norouz and Ziloei oil fields and also two wells outside from Iran are used to check the accuracy of the obtained relation in which they confirm the accuracy of the new relation
  9. Keywords:
  10. Failure Criteria ; In-Situ Stresses ; Mohr-Coloumb Model ; Wellbore Stability ; Mud Window ; Hoek-Brown Method

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