Experimental Studies on the Effect of Mechanical Cleaning Devices on Annular Cuttings Concentration and Applications for Optimizing ERD Systems

Abstract

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.

CFD Method for Predicting Annular Pressure Losses and Cuttings Concentration in Eccentric Horizontal Wells

“…It is believed that, cuttings transported in the annulus are not always affected by a single parameter, but a combination of parameters to ensure efficient hole cleaning [4]. Other studies have also confirmed that increase in fluid velocity results in a decrease in cuttings accumulation in the wellbore [5][6][7]. Ozbayoglu and Sorgun [8] also conducted cuttings transport experiment and developed empirical correlations for estimating pressure losses with the presence of cuttings and drill pipe rotation in horizontal and inclined wellbores.…”

Decaying Swirl Flow and Particle Behavior through the Hole Cleaning Device for Horizontal Drilling of Fossil Fuel

“…Since the 2010s, the application of the hole cleaning device has gradually risen and achieved a remarkable hole cleaning effect. Puymbroeck et al [19][20][21] introduced a compound hole cleaning device with double helix blade small joints. Laboratory experiments and field tests show that the device has excellent cleaning ability of cuttings bed; besides, it improves the degree of hole cleaning by more than 60% and reduces the friction of drilling tools by 30%.…”

Study on Cuttings Transport Efficiency Affected by Stabilizer's Blade Shape in Vertical Wells

“…However, using stabilizer greatly reduces annulus area for drilling fluid as well as cuttings transport efficiency. Especially, studies show the outside profile of stabilizers' blade greatly affects cuttings transport [9,10]. Unreasonable blade shape may lead to bad cuttings transport, back flow, repeated fragmentation, and bit balling; all of these issues will decrease ROP, but few studies have been carried out for the influence on cuttings transport efficiency affected by blade type in vertical wells.…”