Abstract
Efficient cuttings transport and improving rate of penetration (ROP) are two major challenges in horizontal drilling and extended reach drilling. A type of jet mill bit (JMB) may provide an opportunity to catch the two birds with one stone: not only enhancing cuttings transport efficiency but also improving ROP by depressuring at the bottom hole. In this paper, the JMB is further improved and a new type of depressure-dominated JMB is presented; meanwhile, the depressurization capacity of the depressure-dominated JMB is investigated by numerical simulation and experiment. The numerical study shows that low flow-rate ratio helps to enhance the depressurization capacity of the depressure-dominated JMB; for both depressurization and bottom hole cleaning concern, the flow-rate ratio is suggested to be set at approximately 1:1. With all other parameter values being constant, lower dimensionless nozzle-to-throat-area ratio may result in higher depressurization capacity and better bottom hole cleaning, and the optimal dimensionless nozzle-to-throat-area ratio is at approximately 0.15. Experiments also indicate that reducing the dimensionless flow-rate ratio may help to increase the depressurization capacity of the depressure-dominated JMB. This work provides drilling engineers with a promising tool to improve ROP.
Highlights
Horizontal drilling and extended reach drilling have been considered as an ideal technique for developing unconventional oil & gas reservoirs (Gao et al 2009; Chen et al 2016c; Chen and Gao 2018)
Epelle et al (2018) reported that small cuttings transport efficiency can be improved remarkably by improving in the rheological properties of the drilling fluid, while large cuttings still pose a challenge to the wellbore cleaning process despite the rheological enhancement
Chen et al (2016a, b, and c) developed a type of jet mill bit (JMB); this tool proffers a promising solution to the cuttings accumulation problem in horizontal drilling by comminuting cuttings into dustlike scale right after the cuttings are generated in the bottom hole
Summary
Horizontal drilling and extended reach drilling have been considered as an ideal technique for developing unconventional oil & gas reservoirs (Gao et al 2009; Chen et al 2016c; Chen and Gao 2018). Chen et al (2016a, b, and c) developed a type of jet mill bit (JMB); this tool proffers a promising solution to the cuttings accumulation problem in horizontal drilling by comminuting cuttings into dustlike scale right after the cuttings are generated in the bottom hole. As it is, the JMB provides a promising solution to catch two birds with one stone: enhancing cuttings transport efficiency and improving ROP by depressuring at the bottom hole. Junk slots around the JMB can allow cuttings and drilling fluid flowing through the annulus, it may weaken the depressurization capacity and drilling performance of the JMB
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