Abstract

In the oil and gas industry, seismic surveys are used in the search for suitable geological features in which hydrocarbons may be trapped. Seismic surveys are acquired by the generation of seismic waves and the recording of the waves interacting from subsurface geologic horizons and allow scientists to map the subsurface distribution of formations. The surveys can be either surface-seismic surveys or borehole-seismic surveys.

VSI* versatile seismic imagers have been widely used for borehole-seismic services for over a decade. However, the demand for borehole-seismic operations in hostile environments has been growing with the increase in drilling high-pressure, high-temperature wells worldwide; hence, the latest VSI tool has been designed for high-pressure and high-temperature (HPHT) environments and with a focus on data fidelity and acquisition efficiency using a modular design and isolated seismic sensor packages, along with digitization close to the sensor packages. The modular design allows multilevel shuttle configurations and enables flexibility in shuttle spacing for acquiring borehole-seismic data. The small, acoustically isolated seismic sensor packages feature three-component (3C) omnitilt geophone accelerometers, with the sensor packages decoupled from the sonde body, for measuring the particle motion of the formation. This innovative design promotes waveform fidelity by removing tool harmonic noise and tube waves from the borehole-seismic band. In the HPHT VSI tool, heat transfer from the borehole to the electronic boards is minimized by enclosure of the electronics inside of the Dewar flask housing. The performance of the HPHT VSI tool in hostile environments was verified through successful field tests, simulations, and experiments.

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