Controlling factors of remaining oil distribution after water flooding and enhanced oil recovery methods for fracture-cavity carbonate reservoirs in Tahe Oilfield

Measurement of CO2 diffusion coefficients in both bulk liquids and carven filling porous media of fractured-vuggy carbonate reservoirs at 50 MPa and 393 K

“…4 shows the pressure data and t results using eqn ( 7) for the CO 2 -oil system. The CO 2 diffusion coefficient in the oil phase was 4.1243 Â 10 À8 m 2 s À1 at 5.10 cm height in the diffusion cell according to eqn (8), and that in heptane was 1.17 Â 10 À8 m 2 s À1 under similar conditions according to Cadogen et al 20 The diffusion coefficient of CO 2 in the oil phase was higher than that in liquid heptane. The results presented here may contradict the theoretical Stokes-Einstein models, where the diffusivity of a solute decreases in an alkane with viscosity.…”

“…5,6 By injecting gas into the fracture-cavity production unit, gas contacts the formation uid via diffusion, which causes the oil to swell, reduces the oil viscosity, extracts the light component, lowers the interfacial tension (IFT) and suppresses the water crest. [7][8][9][10][11] Therefore, the volumetric sweeping and displacement efficiency are drastically improved.…”

“…5,6 By injecting gas into the fracture-cavity production unit, gas contacts the formation uid via diffusion, which causes the oil to swell, reduces the oil viscosity, extracts the light component, lowers the interfacial tension (IFT) and suppresses the water crest. [7][8][9][10][11] Therefore, the volumetric sweeping and displacement efficiency are drastically improved.The diffusion coefficient is one of the most basic parameters to determine the mixing rate of the injection gas and reservoir liquids. 12-14 A solution of gas in crude oil causes a series of property changes such as reduction in viscosity and volume expansion, which consequently improve the oil mobility and production capability.…”

Predicting Granitic Buried-Hill Reservoirs Using Seismic Reflection data—A Case Study From the Bongor Basin, Southwestern Chad

“…The low-frequency amplitude energy of the reservoir increases when oil and gas are present (Li et al, 2019;Luo et al, 2020). In other words, the energy of the low-frequency component of seismic waves passing through oil-gas reservoirs is stronger than that of seismic waves passing through nonreservoirs (Liu, 2013;Tian et al, 2016;Zheng et al, 2019). It is possible to predict the distribution of fracturedcave reservoirs by using weak seismic spectral variation (Wang et al, 2004;Liu, 2013).…”

Quantitative Analysis of the Main Controlling Factors of Oil Saturation Variation

“…Previous studies have looked at the distribution of remaining oil saturation and the influencing factors [26][27][28][29][30]. These studies mainly focused on static characteristics of the reservoir, such as microscopic pore structure and heterogeneity.…”