This paper discusses the successful design, laboratory testing, and performance of an innovative, low-solids, organophilic-clay-free invert-emulsion fluid (OCF-IEF) used to drill the reservoir section of an extended-reach-drilling (ERD) well. This specially designed drill-in fluid helped maintain the key ERD factors within the specifications necessary and set new limits for drilling performance, thus maximizing the horizontal-section displacement and reservoir drainage and production output.
Introduction
ERD is an operative practice for drilling high-angle wellbores with long horizontal displacement. Typically, a well design is classified as ERD when the horizontal displacement is at least two times the vertical-displacement true vertical depth (TVD). The longest well drilled in the UAE had a measured depth of 35,800 ft, with 18,800 ft of horizontal displacement and a 7,894-ft TVD (Fig. 1). This technique is considered one of the more technically challenging in the industry. However, because of increased reservoir contact, it is generally preferred to conventional well designs.
