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Search for the first entry of the sound wave transmitted through ground layers

Developed for: OOO “GeoPhysTechnika”, Saratov, Russia

Purpose: searching for the first entry of the sound wave emitted by the geophysical probe and transmitted through the ground layers

The given development is intended for the analysis of information received while exploring rock layers. The result of acoustic well surveying, i.e. drillhole measurements, is a signal generated in the form of a wave pattern. Consequently, the main purpose of the project is processing and analysis of wave patterns. Description of the oscillations circulating within the layers is accepted by the application as the baseline data. The application processes the data and generates a number of values delineating a significant component of the signal received during the field testing. Therefore, the application primary tasks are the following:

  • Search for the first entry based on the pre-set conditions (discrimination level, periodicity of the first three half-cycles within the pre-set maximum and minimum periods, disposition in the set time frame)
  • Phases examination

Judging by the time difference between the first entries of transverse and pressure waves, it is determined which rock lays down the wellbore walls with the placed probe. A user gets a number of values to generate a model of the explored rock layers. Two methods of the signal analysis, with and without STC (Slowness Travel time Coherence) are used in the program. The results of input data processing allow generating wave patterns (slowness/time, slowness/frequency) as well as computing waves speed histograms.

The application is currently used to reduce field surveying costs and to build rock layers mathematical models.

Specification

Client: OOO “GeoPhysTechnika” LLC, Saratov, Russia
Area of use: geophysical researches, signal processing
Type (platform): .NET-classes library
Technologies and algorithms in use: .NET, C#, Task Parallel Library (TPL), discrete wavelet-transform, signal peak detection, spline approximation
More information:

References:

  1. Jingping Ji and Bernd Milkereit. Full Waveform Sonic Data From A Fast Formation // 2004 CSEG National Convention. – http://www.cseg.ca/conventions/abstracts/2004/2004abstracts/052S0131-Ji_J_Full_Waveform_Sonic_Data.pdf
  2. Andy St-Onge. Akaike Information Criterion Applied to Detecting First Arrival Times on Microseismic Data // 2011 CSPG CSEG CWLS Convention. – http://www.cspg.org/documents/Conventions/Archives/Annual/2011/058-Akaike_Information_Criterion_Applied_to_Microseismic_Data.pdf
  3. Christopher V. Kimball and Thomas L. Marzetta. Semblance processing of borehole acoustic array data. – http://geophysics.geoscienceworld.org/content/49/3/274.abstract
  4. Borehole Acoustic Waves. – http://www.slb.com/~/media/Files/resources/oilfield_review/ors06/spr06/03_borehole_acoustic_waves.pdf

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