Temperature, mineralogy, and fluid effect on unconventional formation properties
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The goal of this work is to quantitatively study the effects of fluids, composition of the rock, and temperature on the properties of unconventional formations. XRD and XRF tests were used to collect the mineralogy and elemental composition of the samples. To compare the effects of different drilling fluids and shale mineralogy on swelling rates of Marcellus and South Asia shale formations, core samples were half submerged into different fluids and swelling data were collected for seven days. Oil based mud and synthetic oil provided lower swelling rate than 3.5% brine and 7% KCl. The effect of fluid type on dispersion rate was measured using the dispersion test. To study the effect of temperature on the mechanical properties of shale, UCS tests were run on cores exposed to different temperatures. The unconfined compressive strength, Poisson’s ratio, and Young’s modulus for the shale samples varied with different temperature. Lastly, four models to predict the swelling rate of samples based on their elemental composition and type of fluid were developed using raw data from swelling and mineralogy tests. The models could be used to predict how much swelling a formation would exhibit given its elemental composition and type of drilling fluid used.