Experimental Studies on the Effect of Mechanical Cleaning Devices on Annular Cuttings Concentration and Applications for Optimizing ERD Systems
- Ramadan Mohammed Ahmed (U. of Oklahoma) | Munawar Sagheer (U. of Tulsa) | Nicholas Takach (U. of Tulsa) | Reza Majidi (U. of Tulsa) | Mengjiao Yu (U. of Tulsa) | Stefan Z. Miska (U. of Tulsa) | Christophe Rohart | Jean Gilbert Boulet (VAM Drilling)
- Document ID
- Society of Petroleum Engineers
- SPE Annual Technical Conference and Exhibition, 19-22 September, Florence, Italy
- Publication Date
- Document Type
- Conference Paper
- 2010. Society of Petroleum Engineers
- 1.6 Drilling Operations, 4.1.2 Separation and Treating, 1.4 Drillstring Design, 4.1.9 Tanks and storage systems, 4.3.4 Scale, 3 Production and Well Operations, 1.7.7 Cuttings Transport, 1.15 Fundamental Research in Drilling, 1.10.1 Drill string components and drilling tools (tubulars, jars, subs, stabilisers, reamers, etc), 2.1.7 Deepwater Completions Design, 1.10 Drilling Equipment, 1.11 Drilling Fluids and Materials, 4.1.5 Processing Equipment, 1.6.1 Drilling Operation Management
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In horizontal and highly deviated portions of an Extended Reach Drilling (ERD) well, cuttings beds form on the low-side of the annulus. The bed partially blocks the annulus resulting in excessive pressure loss and a higher equivalent circulating density (ECD) that is exacerbated by the increase in length of the annulus. This condition limits hole-cleaning capabilities. As a result, selecting favorable drilling parameters is not always sufficient to overcome the hole cleaning problem. Recently, the use of downhole Mechanical Cleaning Devices (MCDs) has been introduced to the industry to mitigate the problem without inducing excessive ECD. Although the use of these tools is increasing, very limited studies have been conducted to optimize their performance.
This paper presents results of an experimental study that was carried out to evaluate cuttings removal efficiency of MCDs and applications of MCDs for optimizing ERD systems. Experiments were carried out in a large-scale flow loop that has an 8-inch transparent test section. Three different drillpipe sizes were considered in the investigation. The Taguchi approach was implemented to reduce the number of experiments while covering the most relevant parameters such as flow rate, ROP, diameter ratio, tool design and drillpipe rotation speed. For each test, the amount of cuttings accumulated in the test section was determined from weight measurements. Results indicate that the tools significantly reduce the amount of cuttings in the annulus, especially around the MCDs, compared to locations where there is no tool.
Experimental results were evaluated to obtain the overall effect of operating parameters on annular cuttings concentration and develop correlations. The results show that the flow rate and inclination angle have the most significant impact. The correlations are useful to develop an analytical model for designing and optimizing drilling systems with MCDs, either in terms of operating parameters or drillstring design.
Efficient cuttings transport is an important issue in drilling highly deviated and horizontal wells. In directional wells, drilled cuttings tend to accumulate on the lower side of the annulus and form a thick cuttings bed when the flow velocity becomes insufficient to suspend the cuttings bed particles. Particularly, in high-angle and horizontal boreholes, the formation of thick cuttings bed can give rise to numerous difficulties such as lost circulation, differential sticking, high torque and drag. Recently, hydro-mechanical hole cleaning devices such as HydrocleanTM tools have been developed to enhance cuttings transport efficiency in directional wells. These tools are introduced in the drillstring with different spacing arrangements.
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