*Student, M. Tech, Petroleum Engineering Department, Uttaranchal Institute of Technology, Uttaranchal University, Dehradun, India
**Lecturer, Petroleum Engineering Department, Uttaranchal Institute of Technology, Uttaranchal University, Dehradun, India
Online published on 24 October, 2019.
Highly deviated wells may be described as those well whose inclination exceeds 60° for most of their length. Extended reach wells are those having MD/TVD ratio ≥ 2. It is possible to extend directional drilling techniques to increase the inclination to 60° to 90° although certain alterations may have to be made to drilling practices. Certain modifications to standard rig equipment may also be necessary to successfully drill these high angled wells. ERD wells drilled in specific fields and with specific rigs, equipment, personnel, project teams, etc. do not necessarily imply what may be readily achieved in other areas. Because of the myriad of variables which control drilling mechanics and performance, local ERD definitions should be developed in terms of the extent of experience within specific fields and with specific rigs. As one example aspect, the feasibility of ERD wells is inherently tied to the ability to manage wellbore stability. This topic alone is impacted by local geology, in-situ formation stresses, possible tectonic influences, shale reactivity, proposed well inclinations and azimuthal orientations, etc. The primary means of managing wellbore stability via mud weight, mud chemistry, casing points, etc. are likewise impacted by considerations such as loss circulation zones, permeable zones which may cause differential sticking, environmental constraints affecting mud selection and cuttings disposal, and regulatory requirements and production objectives which constrain hole/casing programs.
