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Conventional applications of acoustic logging
This page discusses interpretation of acoustic logging using conventional applications.
Overview
Interpretation of acoustic-log data begins with the slowness values obtained from processing the recorded waveforms. Slowness, or porosity derived from slowness, may be corrected for additional factors before use in applications. Today, log analysis and interpretation is routinely performed by computers during data acquisition (in real time) or in post-acquisition processing in offices and computing centers. Modern interpretation software is built on algorithms derived from the empirical relationships originally used to create a variety of graphical solutions contained in crossplots and nomograms.[1] Because porosity tools vary in their sensitivity to lithology, porosity, and fluid properties, the combination of different measurements allows more-accurate determination of the following kinds of characteristics:
- Porosity
- Petrophysical
- Geological
The logging service companies issue chartbooks with tool-specific charts to facilitate rapid manual determination of:
- Porosity
- Lithology
- Shaly-sand analysis
- Saturation
- Mechanical properties
- Cement-bond evaluation
These charts, which are accompanied by instructions for their use, form the basis for quick-look interpretations and for quality control of computer interpretations.[2][3]
The earliest applications of acoustic-logging measurements made use of compressional slowness, used alone or in combination with resistivity logs and other porosity logs. This group of applications still comprises the basic set of applications for acoustic-log data, which includes:
- Velocity
- Porosity
- Gas identification
- Lithology
- Fluid saturation
- Rock strength
In the 1960s, laboratory studies indicated that shear-wave data could also prove useful in formation evaluation.[4] The development and introduction of reliable shear-wave acquisition and full-waveform logging in the late 1970s and 1980s resulted in improved accuracy in these conventional applications.[5] Further advances throughout the 1980s and 1990s, in both basic and applied research as well as in tool technology, led to new and advanced applications that use shear- and Stoneley-wave amplitude and attenuation (Table 1), e.g.:
- Permeability estimation
- Anisotropy determination
- Direct hydrocarbon indicators
Table 1
Applications
Below are some applications of acoustic logging:
References
- ↑ Fertl, W.H. 1981. Openhole Crossplot Concepts A Powerful Technique in Well Log Analysis. J Pet Technol 33 (3): 535-549. SPE-8115-PA. http://dx.doi.org/10.2118/8115-PA.
- ↑ Bigelow, E.L. 1995. Introduction to Wireline Log Analysis, 1-312. Houston: Baker Atlas.
- ↑ Boyer, S. and Mari, J.-L. 1997. Seismic Surveying and Well Logging Oil and Gas Exploration Techniques, 1-192. Paris: Editions Technip.
- ↑ Pickett, G.R. 1963. Acoustic Character Logs and Their Applications in Formation Evaluation. J Pet Technol 15 (6): 659-667. SPE-452-PA. http://dx.doi.org/10.2118/452-PA.
- ↑ Medlin, W.L. and Alhllall, K.A. 1992. Shear-Wave Porosity Logging in Sands. SPE Form Eval 7 (1): 106-112. SPE-20558-PA. http://dx.doi.org/10.2118/20558-PA.
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