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The onset of erosion of coiled tubing (CT) strings may be difficult to predict in annular fracturing operations. The complete paper describes a methodology of verifying that CT strings have not been subject to erosion caused by annular fracturing operations. An exploration of pumping rates used on these strings in operations also provides field-tested practical guidelines for avoiding erosion when performing annular fracturing jobs. A CT string may be exposed to erosion in the outer surface during CT annular fracturing operations. The critical parameters that may influence the magnitude of erosion include fracturing pump rate, sand concentration, fluid rheology, wellbore geometry, and the grade of CT string.
Shales and other low-permeability formations require multistage completions, hydraulic fracturing, and horizontal wells to produce at economic rates. This course focuses on the multistage completion systems that are used in these applications, including plug-and-perf, ball-activated systems (frac sleeves), and coiled tubing-activated systems (annular fracturing). Participants will learn the different types of multistage completion options and how they compare in different applications. They will also get an overview of low-permeability plays and learn the basics of hydraulic fracturing and refracturing. In the last decade new production from shales and other low-permeability reservoirs that require multistage hydraulic fracturing has significantly influenced the price and supply of hydrocarbons.
Abstract More operators are seeing the production benefits of targeted horizontal annular fracturing. The most active method of annular fracturing in the USA involves ported sleeves installed with the completion and activated via an isolation packer. Initial operations were in lateral lengths of 2,000 to 3,000 ft. However, current operations are planned for accessing up to 10,000 ft laterals. Increasing lateral length results in the traditional access challenges faced by all coiled tubing (CT) operations. The traditional method of lubricant use is the primary option due to its simplicity. The second method is to use fluid hammer tools (FHT). 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 with 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 modelling was performed prior to 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 fluid hammer tools (FHT) for setting the isolation packer, laboratory testing was performed to ensure the bottom-hole assembly (BHA) system compatibility. The lubricant testing and initial field results were reported previously (Livescu and Craig 2014; Livescu et al. 2014a,b). 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.