Abstract

The shale plays have drastically increased production of oil and gas in the US and North America in general. In the past couple of years, there has been tremendous research on understanding the dynamics and phase behavior of fluids at the pore scale in shale rock. The change in bubble point of oils in liquid rich shale play because of the effect of confinement of oils in nano pores has caught attention of the researchers. Our prior research based on modeling and experiments show that kerogen interacts with the oil that leads to changes in bubble point of oils. There has not been any experimental work to account for the presence of kerogen (organic matter) in vapor-liquid equilibrium calculation. Experiments have been performed in this work that show the combined effect of kerogen presence and confinement on oil bubble point.

In the current work, kerogen is isolated from a shale sample by series of acid treatments. The shale rock sample was collected from a prolific US shale play. The isolated kerogen is nano porous and was swelled with light sweet Wyoming crude oil. Differential Scanning Calorimetry is used to measure the changes in bubble point of oil in kerogen. The work, thus accounts for the effect of oil confinement and kerogen-oil interactions on the pressure-volume-temperature (PVT) properties of oil. Results show that the bubble point temperatures are suppressed in the nano pores and in the vicinity of kerogen. The changes in the bubble point of oils in shales affect properties like produced gas-oil ratio, volumes and rates of recovery of petroleum reserves.

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