The Petrophysics of Drilling Fluids and Their Effects on Log Data
- Geoffrey Page (Baker Hughes) | Stephen Vickers (Baker Hughes)
- Document ID
- Society of Petrophysicists and Well-Log Analysts
- Publication Date
- October 2011
- Document Type
- Journal Paper
- 369 - 380
- 2011. Society of Petrophysics and Well Log Analysts
- 3 in the last 30 days
- 356 since 2007
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Drilling fluid are carefully formulated to enable safe and efficient drilling of subsurface formations and to minimize formation damage within reservoir sections. Although the effects of these fluid on log data might have been identified they are generally accepted as an unavoidable consequence of achieving cost-effective and productive wellbores.
The effects of drilling fluid chemicals on log data are generally considered to be minimal, as tool-specific corrections are applied to account for the fluid effects within the borehole. These borehole corrections, however, only adjust tool responses to true measurements of the bulk formation properties, and do not account for the effects of invading fluid on the final petrophysical interpretation. With the introduction of more complex drilling fluid chemistry, accounting for the invading fluid properties becomes more complex and even more significant than when the drilling fluid are simple water-based or invert-oil emulsions. To retain interpretation accuracy, the log analyst might require performing complex modeling of the effects of formate and bromide base brines which induce different log responses than other aqueous fluids.
The formulation of drilling fluid for drilling purposes has been widely documented; however the effects that many common, and not so common, drilling fluid components have on petrophysical measurements are not well documented. Even the physical properties of common make-up brine and standard base oils that may affect basic log data responses have not been completely catalogued. Other components such as precipitating salts and para-magnetic particles may also influence the measurements of some logging tools.
This paper is intended as an overview of the primary effects of drilling fluid chemicals on petrophysical log data. References are provided to assist in additional research on individual mud systems.
|File Size||3 MB||Number of Pages||12|