Browsing by Subject "świder PDC"

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Access status: Open Access ,
Modelling of PDC drill bit whirling
(2007) Prigorovska, Tania O.
At this work it was made the attempt to explain the process of PDC drill bit whirling as an integral part of drilling in real conditions. It was shown that the causes of PDC whirling are not only the rock mass heterogeneity, but drill bit mass misbalance too and it is impossible to obtain absolutely stable drilling system. PDC drill bit previous models were based on the assumption all cutting forces are stable and that PDC drill bit oscillation is self appearable or stochastic. Based on the theory of probability it was defined the value of cutting forces on every PDC cutter and generalized drill face reaction and it was drill bit oscillation and whirling were analyzed.
Access status: Open Access ,
PDC single cutter : the effects of depth of cut and RPM under simulated borehole conditions
(2011) Majidi, Reza; Miska, Stefan; Tammineni, Sandeep
While the weight on bit (WOB) and rotary speed (RPM) are perhaps the most important drilling parameters affecting the rate of penetration, limited information are available about the fundamental mechanisms of rock destruction and the effect of cutting speed and the depth of cut during the cutting process. Experiments were carried out in a high-pressure facility with a 13 mm single PDC cutter to cut Carthage Marble and Indiana Limestone samples with depths of cut in the range of 0.02-0.12 inch and rotary speeds from 30 to 180 RPM at atmospheric and pressurized conditions. Our previous experimentations showed that an increase in the confining pressure as small as 150 PSI could significantly increase the Mechanical Specific Energy (MSE) of the cutting process and reduce the efficiency by half. Recently performed atmospheric and pressurized single cutter tests, showed that a minimum depth of cut was required to efficiently drill the rock samples. MSE required to cut the rock, reached a minimum at depths of cut greater than 0.08 inches for both Indiana Limestone and Carthage Marble samples. Most promising were the results that showed a decrease in MSE at high rotational speeds (RPM 100) and atmospheric pressure, possibly indicating a change in rock failure mechanism. A mathematical model was derived from the balance of forces acting at the PDC cutter that constitutes a single linear relation between the cutting force and the normal force. The characteristic line acts as an indication of bit-rock interaction and can be used to detect the formation and cutter dullness. The model was verified using the experimental data from the single cutter tests. Such observations and analysis provide useful insights into the physics of cutter-rock interaction and are valuable to the improvements of drilling practices selection (WOB, rotary speed, etc) and the rates of penetration.
Access status: Open Access ,
Próba wyznaczenia modelu wiercenia narzędziami PDC na przykładzie wiercenia w wybranych strukturach geologicznych
(2007) Rado, Robert; Lubaś, Jan
PDC tools have high drilling advancement and footage. These tools are efficient and accelerate the drilling rate, thus lowering the cost of drilling. Proper determining of optimal parameters of drilling technology is related with the optimization process. For doing so, it is necessary to identify a mathematical model of drilling with given tools in a respective geologic interval. The mathematical model of drilling with PDC tools for the Carpathian Foredeep is presented in the paper.