Flat rheology invert drilling fluids (those which have thermally independent rheological properties) have been used for years. Initially the applications were in deepwater, but more recently their utility has been seen in many other areas such as extended reach drilling, arctic drilling (or more accurately cold weather drilling) and high angle wells. Although the performance of the flat rheology drilling fluids - stable rheological profile, good hole cleaning and good rates of penetration (ROP) - has helped increase their general acceptance, there still are aspects of these fluids which limited their application. A newly developed Flat Rheology Drilling Fluid (FRDF) addresses these limitations while still maintaining a stable and thermally independent rheological profile. In addition to thermally independent rheology, the benefits that are realized in this new FRDF are:
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Ability to be formulated with a greater variety of base oils and synthetic materials
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Greater ease in engineering of the system by reducing the overall basic product offering, while maintaining fluid properties
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Reduced thixotropic properties of the drilling fluid especially after solids contamination which results in lower and non-progressive gels
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Increased thermal stability of the flat rheological profile These improvements make the FRDF system more versatile and robust, while adding even more applicability on those critical wells where hole cleaning and maintaining a narrow equivalent circulating density are paramount to the success of the well.
Wells involving extended reach drilling, depleted zones or where hole cleaning or barite sag are major concerns are just a few of the type wells that FRDF systems have been used on. This paper also discusses the development and field usage of the new FRDF as well as demonstrates the benefits to a variety of drilling operations with field data and hydraulic simulations
