Overcoming Extended-Reach Challenges for Annular Fracturing

More operators are seeing the production benefits of targeted, horizontal annular fracturing. The most-active method of annular fracturing in the US involves ported sleeves installed with the completion and activated by means of an isolation packer. Initial operations were in lateral lengths of 2,000 to 3,000 ft; however, current operations are planned for accessing lateral lengths up to 10,000 ft. Increasing lateral length results in the traditional access challenges faced by all coiled-tubing operations. The traditional method of lubricant use is the primary option because of its simplicity. The second method is to use fluid-hammer tools (FHTs). These are industry standard for improving efficiency in composite-plug milling operations, but their use in genuine extended-reach operations is not as broad. This paper briefly covers historical ported-annular-fracturing operations and the various methods of achieving increased lateral reach. Results from four wells that have a lateral reach of 7,200 to 10,277 ft are detailed in the paper. The balance of the paper details operational results and optimization from several extended-reach wells. Detailed lateral-reach modeling was performed before all operations. This permitted the determination of the number of expected stages that would require the use of lubricant in the fracture-treatment flush. Given that residual lubricant in the completion is removed by the erosion effects of the proppant in the fracture treatment, each stage would require an additional fluid flush. This gives an opportunity to modify the lubricant concentration, type, and volume in the flush. Before using FHTs for setting the isolation packer, laboratory testing was performed to ensure the bottomhole-assembly-system compatibility. The lubricant testing and initial field results were reported previously (Livescu and Craig 2014; Livescu et al. 2014a, 2014b). This paper provides operators with sufficient case histories of the planned use of an advanced lubricant in genuine extended-reach wells in real-life situations. This knowledge can improve operator confidence in drilling longer laterals for predictable access for annular-fracturing operations.