Planning and Execution of the Longest Horizontal Well in ADCO

This paper discusses the planning process, execution and lessons learned of an advanced horizontal water injector in a tight carbonate reservoir, onshore United Arab Emirates. The well design required a 10,000 ft horizontal section, to be geosteered in a 6⅛-in. hole through a narrow TVD window of 5 ft, just above the oil water contact.

The challenges were multiple, not only from the rig capability and BHA design point of view, but also from the geosteering and formation evaluation aspects pertaining to borehole hydraulics, completion and stimulation. For injection monitoring analysis the completion had to be run with a perforated 3 1/2-in. stinger design to deploy a 19,500 ft distributed temperature sensing (DTS) system to TD. Four main justifications to execute this pilot project were identified:

• to improve injectivity and therefore the area sweep efficiency in the down flank area of the field

• to segment the wellbore to provide for future selective stimulation along 10,000 ft of horizontal section

• to deploy a DTS system to continuously monitor the water injection profile

• to minimize the number of injection wells in the field, reducing CAPEX, OPEX, surface hook ups and field footprint.

The paper discusses the business case for this project, which includes an initial pilot well containing a 5,100 ft lateral section and four extended reach drilling (ERD) wells, each with a 10,000 ft lateral hole section. Furthermore, best practices from the detailed planning phase to the execution of the first extended reach well are reviewed in this paper.