Nicolas Goujon

Development of a MEMS rotation sensor for oilfield applications

A new capacitive microelectromechanical rotation sensor (R-MEMS) with very high performances (low noise, high bandwidth) was developed for oilfield applications. After a thorough design phase based on analytical, finite element and MATLAB/Simulink models, the first R-MEMS prototypes were microfabricated using an optimized deep reactive ion etching (DRIE) process of thick silicon on insulator (SOI) wafers and then characterized in open-loop and closed-loop configurations. Further investigations along with simulations showed different design improvements to lower the noise floor and results with the latest R-MEMS prototypes are presented.

Characterization and attenuation of transverse particle motion noise on multisensor point-receiver streamer

A multicomponent towed streamer measures both pressure and the particle velocity vector. The particle velocity vector enables us to calculate the 3D upgoing wavefield at any desired position within the aperture of the seismic spread and this allows improving not only the temporal bandwidth by removing ghost notches, but also the spatial bandwidth. However, particle motion sensors measure streamer-borne noise with amplitudes typically several orders of magnitude stronger than the corresponding noise recorded by hydrophones at frequencies below about 20 Hz. Therefore, stronger noise attenuation for particle velocity data is needed at these frequencies. In this paper, we introduce a multiscale noise attenuation algorithm that provides a high-fidelity particle motion measurement at frequencies down to 3 Hz.

Applications of piezoelectric materials in oilfield services

We have described four important applications for piezoelectric materials in the oilfield services industry. High piezoelectric coupling materials are always sought after in developing our devices. However the high coupling materials invariably are ceramics-based and they tend to operate at a disadvantage into a liquid medium in terms of efficiency and bandwidth. Solutions exist to address these problems, such as matching layers and composite materials. But they pose extra complications in a harsh operating environment. It would be desirable to have a high-coupling, low-impedance piezoelectric materials as additional choices. As the industry ventures into ever-deeper and hotter wells, new high-coupling, and higher Curie temperature materials would be required.

Sensor dynamic range for seismic acquisition at the seafloor

Some of the new seafloor acquisition systems contain accelerometers instead of conventional geophones that record particle velocity. A study of the dynamic range needed for recording seismic data at the seafloor in both acceleration and velocity domains is presented. First break at the seafloor is modeled, and the maximum amplitudes in acceleration and velocity are calculated. Ambient noise spectra are presented in both domains, and dynamic ranges are then calculated.