Drilling bits which exploit the destructive energy of cavitation are being developed. A systematic series of tests is now under way, first to establish feasibility, and then to define the effective adaptation of the CAVIJET™ cavitating water jet method for augmenting the cutting action of mechanical deep-hole drilling bits. Successful drilling tests, using a 1/4-in. (6.4-mm) CAVIJET nozzle, were performed at atmospheric pressure and in a test chamber which provided simulated wellbore pressures up to 3000 psi(21 MPa). The effect of back pressure on standoff distance, and a comparison of steady jet versus CAVIJET cutting efficiencies are discussed.

We report on the discovery and testing of a downhole sparker source that is able to generate acoustic signals with peak frequencies from 2 to 1000 Hz. The sparker can be configured such that the energy of the produced acoustic signals lies within a spectral band that is suitable for transmission lengths of the order of thousands of feet, making it a viable source for single-well imaging and reverse vertical seismic profiling. The sparker produces repeatable shots and allows a firing rate much less than typical listening times in borehole seismic applications. Together with its robust design and reliability the described sparker can be operated for thousands of shots before spark plug maintenance is needed. This paper summarizes the development of the tool and presents results from recent field tests.

Commercial introduction of Microhole Technology to the gas and oil drilling industry requires an effective downhole drive mechanism which operates efficiently at relatively high RPM and low bit weight for delivering efficient power to the special high RPM drill bit for ensuring both high penetration rate and long bit life. This project entails developing and testing a more efficient 2-7/8 in. diameter Turbodrill and a novel 4-1/8 in. diameter drill bit for drilling with coiled tubing. The high-power Turbodrill were developed to deliver efficient power, and the more durable drill bit employed high-temperature cutters that can more effectively drill hard and abrasive rock. This project teams Schlumberger Smith Neyrfor and Smith Bits, and NASA AMES Research Center with Technology International, Inc (TII), to deliver a downhole, hydraulically-driven power unit, matched with a custom drill bit designed to drill 4-1/8 in. boreholes with a purpose-built coiled tubing rig.

A breakthrough has been discovered for controlling seismic sources to generate selectable low frequencies applicable to many seismic applications. All possible borehole pulsed sources, including hydraulically driven devices, explosives, and etc., by their very nature produce high frequencies. This is counter to the need for long transmission through rock. Specifically, we are reporting the application of an otherwise high frequency sparker source on the drill string for Drill Bit Seismic While Drilling (SWD). The low frequency source provides real-time imaging in deep (15,000 feet+) high-temperature (150°C) high-pressure (HTHP) wells ahead of the bit for accurate pore pressure determinations and geosteering, reservoir model verification, and near wellbore diagnostics. Furthermore, to have additional energy available at the drill bit can result in increased rates of penetration. Introduction It has been said, " The time is coming when we will not drill without looking ahead of the bit anymore than we would drive at night without headlights - occasionally shining a lamp to see what we hit.?? An alternative seismic source for the roller bit as it was being replaced by the PDC bit is something oil and service companies have sought since the early 1990's. A breakthrough has been discovered for controlling seismic sources to generate selectable low frequencies (< 40 Hz) applicable to many seismic applications. All possible borehole pulsed sources, including hydraulically driven devices, sparkers, explosives, etc., by their very nature produce high frequencies. This is counter to the need for long distance transmission through rock. Specifically, we have demonstrated the application of an otherwise high frequency sparker source which can be encorporated into a drill bit for Drill Bit Seismic While Drilling (SWD). The low frequency source, capable of creating selectable mid-band frequencies of 1 to 20 Hz, provides a source to perform real-time imaging in deep (15,000 feet+), high-temperature (150 degrees C), high-pressure (HTHP) wells for (a) geosteering, (b) accurate seismic hole depth, (c) accurate pore pressure determinations ahead of the bit, (d) near wellbore diagnostics with a downhole receiver and wired drill pipe, and (e) reservoir model verification. Furthermore, to have additional energy available at the drill bit for rock desintergation can result in increased rates of penetration.

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