Measurement/Logging While Drilling (M/LWD)
As one single part of the Bottom Hole Assembly (BHA) piezocomposite actuators takes place in the field M/LWD. In the BHA piezocomposite actuators are used to generate sonic signals. These signals are reflected at the formation interface and/or at the bore hole coating. They deliver information about the coating and the surrounding formation. It is necessary to drown out the noise of the drill bit. Piezocomposite actuators generate frequencies of above 10 kHz. Thus it is possible to drown out the drill bits noise in a distance of 10 m/32 ft. So it is possible to generate analyzable signals during the drilling process. That’s why piezocomposite actuators from piezosystem jena save production time.
Pore Pressure Measurement in Oil Wells
U.S. patent US 7331223 B2 describes a procedure for fast pore pressure measurement in the well. A piston oscillates between extended and retracted positions and creates a fluid movement of the resource (e.g. oil). This fluid movement jets through the pores of the formation and provides a fast and precise pore pressure measurement.
Components used in the Bottom Hole Assembly (BHA) must withstand severe conditions e.g. high temperatures and high pressures (HT/HP). Piezocomposite actuators from piezosystem jena are well suited to generate the necessary oscillation even under the extreme conditions in the well. Piezocomposite actuators generate oscillations with frequencies up to 100 kHz and withstand temperatures over 200 °C/392 °F and high pressures without significant performance loss.
Classic methods for the excitation of seismic waves are usually shock events like hammer strokes, falling weights or detonations. During the last time harmonic excitation with seismic vibrators (vibroseis) gains ground. Usually this method uses trucks that are equipped with a vibrating plate that are driven hydraulically. The properties of such systems are:
- Frequencies up to a few 100 Hz
- Forces of some 100 kN
- Accelerations of a few g
- Variable frequency
- Fast, mobile excitation system
Due to their large size such systems are inapplicable for investigations at locations that are difficult to access. In fact there are approaches for more compact systems but these systems generate much smaller forces. Furthermore the signals from the mainly used hydraulic systems have high distortion factors.
Piezo materials show high energy densities which results in a high force generation of over 10 kN at relatively small sizes. Therefore it is possible to perform investigations at locations that are difficult to access. Furthermore the use of piezo technology allows a free choice of the signal waveform.
- Tunable frequencies up to several 100 Hz
- Force modulation over 10 kN
- Arbitrary waveform
- Compact size
Characteristics - Geo-Shaker PiSha: - Coupling to the ground via base plate - Force-generation: reaction / acceleration forces in conjunction with seismic masses - Seismic mass up to 200 kg - Max. force modulation ca. ± 15 kN - Basic response: typically at 200 Hz - Max. vibration amplitude of 80 microns