What is It About Shaly Sands? Shaly Sand Tutorial No. 3 of 3
- E. C. Thomas (Bayou Petrophysics)
- Document ID
- Society of Petrophysicists and Well-Log Analysts
- Publication Date
- June 2018
- Document Type
- Journal Paper
- 276 - 287
- 2018. Society of Petrophysicists & Well Log Analysts
- 7 in the last 30 days
- 295 since 2007
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Editor’s comment: This article is part of a series of short “tutorial-like” notes styled to mentor users of digital well logs in becoming confident practitioners of petrophysics.
At the close of Shaly-Sand Tutorial Part 2, I implied, or sort-of promised that this final part would provide some guidance or at least guidelines on the application of my favorite models (equations, transforms, or any of your personal preference names) used to calculate water saturation from a combination of electrical conductivity (i.e., inverse of resistivity), total porosity, formation water salinity, fitting parameters based on rock types (m*, n*), and of course, formation temperature. I need not remind you that all of these properties/parameters listed above can and do vary rapidly with depth (vertically) and transversely (horizontally) across a given reservoir.
I once requested a second core in a large reservoir which was turned down by the Division Engineering Manager using the following reason: “Easy, I am really doing you a favor because if the second core and its analyses are different than the first, you will spend a lot of time understanding the differences, and I know you will be back with a request for a third core to help in this investigation.” This fellow turned a deaf ear to all arguments that I fully expected that each core would be different and only through such sorts of studies could we ever improve our ability to predict recovery efficiency and sweep. “Anyway, that’s not the job assignment of a petrophysical engineer. Leave that job to the experts.” To me it was obvious that this manager did not know that he did not know the influence that geology and petrophysics played in selecting the correct earth model to simulate with mathematical models.
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