Probing the mechanism of in situ oil droplet swelling during low salinity water flooding

Volumetric Swelling of Bakken Crude Oil with Carbon Dioxide and Hydrocarbon Gases at 110 °C and Pressures of up to 34.5 Megapascals

“…Experimental hydrocarbon gas solubilities for a light oil similar to our Bakken test oil and our 110 °C temperature are too limited to allow valid comparisons, especially since gas solubilities vary greatly with the oil composition and the test temperature. 49,53,56,57,63,67 However, the relative solubilities for methane, ethane, and propane in crude oil, as shown in Figure 4, are consistent with those reported by Lindsly, 69 DeRuiter et al, 70 and Schwarz and Prausnitz. 71 More experimental solubility data for carbon dioxide are available with a larger range of oils and temperatures and have been reported in a review of available experimental data by Rostami et al 67 They reported a range of carbon dioxide solubilities in crude oils from 0.12 to 0.72 mole fraction at temperatures ranging from 28 to 124 °C and pressures of up to 33 MPa.…”

“…In addition, carbon dioxide dissolves into the bulk water, which increases the water's acidity and ionic strength, factors that can affect the volumetric swelling of crude oil, as reported in "carbonated water" studies. 51,56,59,62,64 The volume increase of the oil-dominated phase with injected carbon dioxide is enhanced by having water in the cell at higher pressures, results that are consistent with the carbonated water observations of Nowrouzi et al 51 and Huang et al 63 Water also affects the shape of the oil expansion behavior. With no water present, oil swelling with carbon dioxide increases to its MMP of 17.5 MPa, then a drop in the volume of the oil-dominated phase is observed with increasing pressures as more oil hydrocarbons dissolve into the upper gas-dominated phase.…”

“…22 MPa. Both continuous oil swelling with carbon dioxide (with no plateau around MMP) and discontinuous oil swelling (where the oil-dominated phase increases in volume up to MMP, then shows no increase or even a drop in oil volume as pressure is increased to around the MMP, and then shows renewed swelling at higher pressures) have been reported. ,,,, Differences in the oil swelling profiles occur because the type of oil swelling behavior is influenced by the oil composition, injected gas, temperature, and the presence or absence of water. ,− ,,,,,,,, …”

“…All experiments were conducted at typical Bakken field conditions of 110 °C and pressures of up to 34.5 MPa (5000 psi). A variety of approaches have been used to determine crude oil swelling that can be categorized by those using a variable-volume cell − and those using a fixed-volume cell (most often by a “pendant drop” approach). − In the present work, volumetric swelling of the Bakken crude oil was performed using a tall and narrow fixed-volume high-pressure cell similar to the apparatus reported by Ren and Scurto and Tsau et al The use of this tall narrow cell allows simpler measurements of the changes in oil volume during gas injection than using the “pendant drop” methods that must measure the volume of the rounded “drop-shaped” oil sample. The cell used in the present work (“G” in Figure ) is rated at 34.5 MPA (5000 psi) and has an 8 mL internal volume and a 12- × 95 mm viewing window (Model TXT-11, Inferno Manufacturing Corporation, Shreveport, LA).…”

“…injected gas, temperature, and the presence or absence of water. 43,[45][46][47]49,50,52,54,59,61,63,66 Most oil swelling studies have focused on the use of carbon dioxide, and there is a lack of comparative experimental data for carbon dioxide and hydrocarbon gases. However, Yang and Gu 52 have reported a comparison of swelling behavior for a heavy oil at 24 °C using carbon dioxide, methane, ethane, and propane at fairly low pressures (up to supply tank pressures for each gas).…”