TY - THES

T1 - Comparison of the Predictive Models of Rotary Drilling Performance with respect to Rock Hardness

AU - Smith, Esteban

N1 - embargoed until null

PY - 2012

Y1 - 2012

N2 - Rotary drilling is the main method used to create blastholes for surface mining operations. The rotary drilling performance is determined by several factors like operational parameters applied by driller, rock hardness, mine altitude, drill rig design and main components of the rig like feed system such as chain, rack & pinion or by ropes. El Abra is one of the most important copper ore mines in South America, located in the north of Chile. This mine is permanently looking for improving drilling performance and specially rate of penetration (ROP). This report considers a wide literature review of different authors who have been developing and improving their ROP predictive models. Some of them made their initial research in the decade of 1960 and continue their work to these days. Most of the authors found in the literature have developed their predictive models using field data from iron ore or even coal mines around the world. No information is available of validation of the predictive models in copper ore mines. During this report several comparison were made to correlate ROP with rock hardness with real field information from El Abra mine. The performance data from field was correlated with the predictive models found in the literature survey using real applied operational parameters as pulldown and rotary speed. The rock hardness is evaluated on site using the Point Load Strength method based on ASTM norm. Rock samples are taken every 50 meters and the result is plotted by bench then an empirical correlation has been used to determine Uniaxial Compressive Strength which is used to compare ROP with the predictive models. Several details has been considered to achieve a relevant correlation between ROP and rock hardness like using only one bit model, using standard pipe diameter which leads to the bailing velocity using the compressor installed on the rig among other factors. The results achieved show certain correlation with some of the predictive models like the one from Smith-Gruner but is not the same case in all drill rigs evaluated and all rock conditions. Also a new ROP predictive model was developed based on the results achieved. This new predictive model shows good correlation with the field performance data and can be used for future drilling forecast at El Abra. The new predictive model found will be a useful tool for Sandvik for any new project regarding estimation of total drilling cost including drill rig capital cost which is strongly related to ROP and for estimating tools consumption and cost.

AB - Rotary drilling is the main method used to create blastholes for surface mining operations. The rotary drilling performance is determined by several factors like operational parameters applied by driller, rock hardness, mine altitude, drill rig design and main components of the rig like feed system such as chain, rack & pinion or by ropes. El Abra is one of the most important copper ore mines in South America, located in the north of Chile. This mine is permanently looking for improving drilling performance and specially rate of penetration (ROP). This report considers a wide literature review of different authors who have been developing and improving their ROP predictive models. Some of them made their initial research in the decade of 1960 and continue their work to these days. Most of the authors found in the literature have developed their predictive models using field data from iron ore or even coal mines around the world. No information is available of validation of the predictive models in copper ore mines. During this report several comparison were made to correlate ROP with rock hardness with real field information from El Abra mine. The performance data from field was correlated with the predictive models found in the literature survey using real applied operational parameters as pulldown and rotary speed. The rock hardness is evaluated on site using the Point Load Strength method based on ASTM norm. Rock samples are taken every 50 meters and the result is plotted by bench then an empirical correlation has been used to determine Uniaxial Compressive Strength which is used to compare ROP with the predictive models. Several details has been considered to achieve a relevant correlation between ROP and rock hardness like using only one bit model, using standard pipe diameter which leads to the bailing velocity using the compressor installed on the rig among other factors. The results achieved show certain correlation with some of the predictive models like the one from Smith-Gruner but is not the same case in all drill rigs evaluated and all rock conditions. Also a new ROP predictive model was developed based on the results achieved. This new predictive model shows good correlation with the field performance data and can be used for future drilling forecast at El Abra. The new predictive model found will be a useful tool for Sandvik for any new project regarding estimation of total drilling cost including drill rig capital cost which is strongly related to ROP and for estimating tools consumption and cost.

M3 - Master's Thesis (University Course)

ER -