| abstract |
A method for evaluating drilling fluids to be used with clay-rich rocks such as shales which comprises collecting shales so as to preserve the downhole hydration condition and then submitting such preserved shale to Thermo-Gravimetric Analysis, so as to obtain the derivative curve of mass with respect to temperature, then immersing a sample of the same piece of rock in the drilling fluid of which the interaction with the clay-rich rock is to be ascertained and obtaining TGA analysis at successive periods of time of immersion of the sample, so as to determine the modifications undergone by the sample immersed in the drillling fluid. From the modifications undergone by the sample it is possible to evaluate the adequacy of the drilling fluid to be contacted with the clay-rich rock. |