- Title
- Upper limit of borehole fluid pressure to prevent near wellbore shear failure
- Creator
- Huang, Jinsong; Wong, Sau-Wai
- Relation
- 14th International Conference of International Association for Computer Methods and Recent Advances in Geomechanics. Computer Methods and Recent Advances in Geomechanics : Proceedings of the 14th International Conference of International Association for Computer Methods and Recent Advances in Geomechanics (Kyoto, Japan 22-25 September 2014) p. 1687-1690
- Publisher Link
- http://dx.doi.org/10.1201/b17435-298
- Publisher
- CRC Press
- Resource Type
- conference paper
- Date
- 2015
- Description
- In deep drilling operation, borehole collapse due to insufficient drilling fluid pressure and borehole fracturing as a result of excessive drilling fluid pressure are two major modes of borehole failure. The latter may result in severe loss of drilling fluid into the formation, resulting in potential well control issues with influx of high pressure fluid or gas from adjacent formation layers. To prevent drilling fluid loss, the fluid pressure must not exceed an upper limit, otherwise the borehole will fail in tension or fracture. However, if the fluid pressure is too low, the borehole may collapse or fail in compression. Drilling fluid pressure window is therefore typically set by the upper limit of tensile failure and the lower limit of compressive failure. If the stress state and rock strength require a lower limit which is close to the upper limit, then the drilling fluid pressure design needs to stay within a very narrow window and consequently the feasibility of drilling may be questioned. Based on rigorous mechanics principles, this paper shows that it is possible to experience shear failure due to increasing drilling fluid pressure even before it reaches the upper limit of tensile failure. This may mean a more restricting drilling fluid pressure window in drilling weaker rocks. Implications of near wellbore shear failure are also briefly discussed in the context of water injection design which relies on injection at high pressure.
- Identifier
- http://hdl.handle.net/1959.13/1316019
- Identifier
- uon:23058
- Identifier
- ISBN:9781138001480
- Language
- eng
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