Fundamentals of log analysis. Part 7: Determining shaliness from logs
- S.A. Holditch and Associates Inc., College Station, TX (United States)
Accurate log analysis must take into account how shaliness of rocks affects well logs. Porosity is calculated from neutron, density and acoustic logs, all of which are influenced by rock shaliness. Failure to properly take into account the impact of shaliness will result in errors in log-derived porosity. Water saturation, which is calculated from porosity and resistivity, is also affected by shaliness. Failure to correct for shaliness will therefore compound errors in water saturation calculations. These errors are further compounded in estimating calculated permeability. Shale indicators include the gamma ray log, SP log, neutron-density crossplot, neutron log, resistivity log, neutron-acoustic crossplot and acoustic-density crossplot. The approach for each shale indicator is similar. Some detail of the three most common shale indicators, the gamma ray log, SP log and neutron-density crossplot, will be discussed. The equations for calculating shaliness from logs can be found in the literature. Following is a brief discussion of the most common shale indicators and some examples of their use.
- OSTI ID:
- 455426
- Journal Information:
- World Oil, Journal Name: World Oil Journal Issue: 3 Vol. 218; ISSN 0043-8790; ISSN WOOIAS
- Country of Publication:
- United States
- Language:
- English
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