Browsing by Author "Nguyen, Thanh N."

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Access status: Open Access ,
Experimental study of hydraulic sweeps in horizontal wells
(2010) Nguyen, Thanh N.; Miska, Stefan; Yu, Mengjiao; Takach, Nicholas E.; Ahmed, Ramdan
Drilling fluid sweeps are commonly run in the field to help clean the borehole of cuttings that have not been removed with normal drilling fluid circulation, especially in high angle or extended reach wells where efficient hole cleaning is more difficult to maintain. This study focuses on the use of conventional and enhanced sweeps in horizontal well bores. Not much information pertaining to the use of drilling fluid sweeps is available in the literature. Furthermore, there has been a lack of agreement as to which types of sweep fluids are most effective. Conventional sweeps most often include high viscosity fluids, high density fluids or a combination of both. In addition to conventional sweep fluids, an attempt was made to use enhanced sweep fluids, in which surfactants are used to attach cuttings to oil droplets that are intentionally introduced to the drilling fluid system. Because of their low density, oil droplets can have the ability to keep cuttings particles in suspension. The use of oil droplets is a new concept in cleaning horizontal and deviated wellbores. This work focuses on experimental analysis of sweep fluids with the goal of quantifying the sweep "efficiency". A small-scale sweep loop (SSL) was mainly used to conduct sweep experiments. Moreover, some experiments were carried out in a field-scale flow loop that operates at low-pressure ambient temperature (LPAT) conditions. Results show that pipe rotation plays a very important role in improving hole cleaning. Particularly, the improvement is substantial with high-viscosity fluids. The rotation of pipe has agitation effect that forces the cuttings particles into the main flow and facilitates the removal process. As anticipated, increasing the flow rate enhances the sweep efficiency or cuttings removal regardless of the drillpipe rotation. Furthermore, the study suggests that with a more rigorous evaluation of sweep efficiency, one can objectively determine the type and frequency of drilling sweep. The results of this study are useful for selection of the optimal sweep fluid.