As hydrocarbon production costs rise, the need for greater completion and production efficiency is becoming increasingly important. The Haley Field in the Delaware Basin of West Texas has begun utilizing frac baffles in order to improve the overall efficiency of the multi-stage completion process. The frac baffles, which are strategically placed within the casing string, allow for zonal isolation by means of dropping a frac ball that seats on the frac baffle at the specified depth. The isolated zone is then ready to be perforated and fractured.
The process of utilizing frac baffles has proven to be more efficient compared to the traditional method of setting composite bridge plugs for zonal isolation. First, the need for wireline is reduced because there is no need to set composite bridge plugs. Additionally, the challenges experienced with setting and milling the composite bridges plugs are completely eliminated. Finally, the processes of perforating, stimulating, and coiled tubing milling have been dramatically improved.
In particular, coiled tubing milling of the frac baffles / balls has improved in the areas of milling speed, coiled tubing cycling, and circulation of milled particles returned. Most important, is the significant operational time savings, which allows the well to be brought on production faster.
Since October 2006, approximately 30 wells have been completed with this method. This paper provides an introduction to the frac baffle technology and shows how the utilization of frac baffles has improved the efficiency of the completion process. Specifically, the improvement with coiled tubing milling of the frac baffles / balls over the traditional composite bridge plugs is compared and discussed.
The Haley Field is located in west Texas between the towns of Kermit and Mentone in Loving County (Figure 1). The field was discovered in 1983 and is comprised of approximately 150 gas wells ranging from 15,000 to 18,000 feet in depth. A large independent operator entered the field in 2002 and holds a major land position in the field's central development area. The operator has drilled and completed approximately 90 gas wells.
The gas field produces from the Pennsylvanian age rock formation. The primary producing intervals in the Haley Field are all over-pressured and consist of the Morrow, Atoka, and Strawn formations (Figure 2). The pay interval is comprised of up to 4,000 feet of a stacked conglomerate that ranges in depth from 14,000 to 18,000 feet. The pay system in the Haley Field is a lithologically complex system containing shales, sandstones, limestones, and spiculites. The main source of gas in the field derives from channeled pay sands that range from 2 feet to 50 feet in net thickness.
The Haley field is unique in that the wells exhibit diverse characteristics and performances. The field operates under a 640 acre spacing. The pay zones are extremely discontinuous and pinchouts are evident. For example, a sand in one well could be non-existent in a well in an adjacent section. This discontinuity presents challenges when selecting well locations for potential drill sites.