Theoretical method for detecting in situ PDC bit dull and lithology change : Kuru, E; Wojtanowicz, A...

Drilling

932298 Theoretical method for detecting in situ PDC bit dull and lithology change Kuru, E; Wojtanowicz, A K Can Pet Technol V31, N7, Sept 1992, P35-40

PDC bits are sensitive to formation properties and operating conditions. A method has been developed to allow estimation of bit condition while drilling and to detect lithoiogy changes. A diagnostic plot is made of two dimensionless groups which contain measured values of torque, weight on bit, rotary speed, and penetration rate. This plot is a unique indicator of bit/rock interaction and is independent of bit operational vari- ables. Instantaneous wear can be computed from coordinates of the straight line points. Rapid formation changes are indi- cated by discontinuities in the diagnostic plot.

932299 Microwave-assisted drilling in hard rock Lindroth, D P; Berglund, W R; Morrell, R J; Blair, J R Min Engng V44, N9, Sept 1992, Pl159-1163

The combination of two or more energy processes has the potential to overcome the fragmentation limitations of each alone. The potential of combining microwave heating and mechanical methods in rotary drag pick cutting of hard rocks has been assessed. Pilot scale commercially available equip- ment using microwave energy at the standard industrial fre- quency of 2.45GHz was used. Test results in granodiorite and basalt rocks are presented. Penetration rate increase and decrease in direct drilling costs are found.

932300 Soft formation insert bits improve ROP and lower costs per foot Grimes, B; Scott, D Oil Gas J V90, N33, 17 Aug 1992, P82-87

The original rolling cone tungsten carbide insert (TCI) rock bits were developed for use in hard and abrasive formations. Developments in bit design and materials have led to the ultrasoft TCI bits for use in softer rocks. These bits, with longer insert projections, showed increased penetration rate at lower weight on bit than conventional TCI bits when tested on a medium hard bailing-prone shale in a bottom hole simula- tor. This can result in lower drilling costs as less energy is used to accomplish the same amount of useful work. Field data confirming these experiments are presented.

932301 Mixed metal hydroxide drilling fluid minimizes well bore washouts Lavoix, F; Lewis, M Oil Gas J II90, N39, 28 Sept 1992, P87-90

Mixed metal hydroxide (MMH)/bentonite drilling fluids are slurries with unusual rheology and suspension characteristics. The electrochemical basis for their properties is outlined. Suc- cessful application of MMH fluids in troublesome Vanji sand- stone formations, where severe washout problems had previously occurred, is described. Cost reductions resulted from increased productivity (lower coring time and improved weilbore stability) and reduced direct costs of drilling fluids as a result of lower seepage losses and better solids removal and tolerance.

110A

932302 Determination of optimal air flow rate in air drilling Adewumi, M A; Tian, S Pet Sci Engng VS, N1, July 1992, PI-11

To effectively utilise air drilling it is necessary to know and understand design parameters such as optimal transport veloc- ity, power requirements, and choking velocity. A fundamental hydrodynamic multiphase flow model of air drilling is presented. Its viability as a predictive tool is established by extensive parametric analysis. Effects of gas flow rate, rate of penetration, particle density, and effective particle diameter on efficiency are illustrated.

932303 Development of a thermal mechanical drill for sampling ice and rock from great depths Das, D K; Koci, B R; Kelley, J J Tunnlg Underground Space Technol V7, N4, Oct 1992, P377- 382

Recovering deep cores of glacial ice or of rocks from beneath glaciers requires special care. A new system based on combina- tion of hot water drilling and mechanical drilling is illustrated. Hot water drilling is used to obtain rapid access to interesting sampling areas, then downhole drilling and conventional wire- line technology used to cut and recover cores for examination. A thermal model of the effect of the drilling on the cores is included.

Blasting

See also: 932143, 932293

932304 Blast optimization and stability enhancement through geotechnical mapping at Highland Valley Copper Daly, S; Assmus, D CIM Bull V85, N962, July-Aug 1992, P78-84

Poor fragmentation, high toe areas, excessive shovel wear, and the need to re-drill and blast were found in areas of tough waste rock (quartz monzonite) in the Lornex pit. The charac- ter and extent of these zones were investigated by geological mapping and study of mine operating records. Distinct zones were identified and classified as poor, fair, or good according to diggability and blast procedures needed. Blast patterns have been adjusted for each zone to optimise mine output and con- siderable cost savings have resulted. Unstable slope areas were also identified in this work and remedial measures have been taken.

932305 Effects of quality of bulk commercial explosives on blast performance Cameron, A; Grouhel, P Proc 3rd International Symposium on Rock Fragmentation by Blasting, Brisbane, 26-31 August 1990 P335-343. Publ Parkville: AuslMM, 1990

Blast performance optimisation requires choice of explosive to match particular conditions and objectives. Techniques to characterise explosives performance have been investigated at the JKMRC, Australia. Results from several mine sites indi- cate that different explosives perform differently according to conditions and that performance of any one explosive can vary markedly. Explosive parameters (velocity of detonation, gas energy, shock energy) and factors which affect them have been evaluated. Selection of suitable explosives for particular situations is discussed.

© 1993 Pergamon Press Ltd. Reproduction not permitted