James D. Blacic

Hydraulic hammer drilling technology: Developments and capabilities

Percussion drilling technology was considered many years ago as one of the best approaches for hard rock drilling. Unfortunately the efficiency of most hydraulic hammer (HH) designs was very low (8% maximum), so they were successfully used in shallow boreholes only. Thirty years of research and field drilling experience with HH application in Former Soviet Union (FSU) countries led to the development of a new generation of HH designs with a proven efficiency of 40%. That advance achieved good operational results in hard rock at depths up to 2,000 m and more. The most recent research has shown that there are opportunities to increase HH efficiency up to 70%. This paper presents HH basic design principles and operational features. The advantages of HH technology for coiled-tubing drilling is shown on the basis of test results recently conducted in the US.

Remote elemental analysis using laser-induced breakdown spectroscopy

Focusing powerful laser pulses on a material produces microplasmas that vaporize and excite a small amount of the sample. By spectrally resolving the plasma emission, the elemental composition of the material can be determined. This method, termed laser-induced breakdown spectroscopy (LIBS), has many advantages that make it particularly suited for field-based monitoring. These include: simplicity, multielement detection capability, minimal sample preparation, and remote analysis capability. The remote elemental analysis capability of LIBS is unique compared to other conventional analysis methods. Remote analysis can be provided either by direct focusing of laser pulses on a distant object or by fiber optic delivery of the laser energy to the sample. To date, useful spectra of rock samples have been obtained by projecting the laser pulses out to a distance of 24 meters and collecting the plasma light with a simple lens system. Elements at major and minor concentrations were easily detected. Using fiber optic delivery of the laser pulses, LIBS spectra can be obtained from samples in relatively inaccessible locations (e.g. down a borehole, in a reactor). Laser pulses of 80 mJ at 10 Hz repetition rate have been used to remotely generate the laser plasmas and to collect the plasma light using a single fiber optic.