Horizontal sidetracks offer a very viable technique for rejuvenating production in the redevelopment of brown fields. In brown fields where significant reserves exist, but occur as scattered pockets of by-passed oil, or in stacked reservoirs, their development with new wells will hardly satisfy economic screening criteria. The abundance of old wells that have drained the recoverable reserves in their drainage area and are either producing at very low rates or are closed-in, make horizontal sidetracks a viable tool for rejuvenating production and maximising existing assets.
With a vision to improve production in SPDC by 60% in 2004 and by over 200% (to 2.5 MMbopd) in the year 2010, producing the limit or sweating the existing brown fields is now a key factor. Most new wells are now horizontal completions, due to their higher productivity over vertical or inclined wells. This paper presents the benefits of horizontal sidetracks as a productivity improvement tool that was used to boost production from Obigbo North (one of SPDC-E brown fields) by more than 10,000 BOPD in 1999 alone. It discusses production gains, geology, well construction, completion types, environmental benefits and petrophysical data acquisition and interpretation problems that could be encountered with horizontal sidetracks in brown fields, based on our experience.