Phase Behaviour and Viscosity Reduction of CO2-Heavy Oil Systems at High Pressures and Elevated Temperatures

2014 ◽  
Author(s):  
Xiaoli Li ◽  
Daoyong Tony Yang ◽  
Zhaoqi Fan
Keyword(s):  
Heavy Oil ◽  
High Pressures ◽  
Elevated Temperatures ◽  
Phase Behaviour ◽  
Viscosity Reduction ◽  
Reduction Of Co2

Enhanced Swelling Effect and Viscosity Reduction of Solvent(s)/CO2/Heavy-Oil Systems

SPE Journal ◽  
2013 ◽  
Vol 18 (04) ◽  
pp. 695-707 ◽  
Author(s):  
Huazhou Li ◽  
Sixu Zheng ◽  
Daoyong Yang
Keyword(s):  
Molecular Weight ◽  
Oil Recovery ◽  
Heavy Oil ◽  
Good Accuracy ◽  
Saturation Pressure ◽  
Viscosity Reduction ◽  
Binary Interaction ◽  
Binary Interaction Parameter ◽  
Reduction Of Co2 ◽  
Swelling Factor

Summary In this paper, techniques have been developed to examine the enhanced swelling effect and viscosity reduction of CO2-saturated heavy oil with the addition of either solvent C3H8 or solvent n-C4H10. Experimentally, pressure/volume/temperature (PVT) tests are conducted to measure the saturation pressure, swelling factor, and viscosity of the C3H8/heavy-oil system, the C3H8/CO2/heavy-oil system, and the n-C4H10/CO2/heavy-oil system, respectively, in the overall temperature range of 280.45 to 391.55 K. It has been found that an increased swelling effect of heavy oil is obtained by adding the gas solvent C3H8 or n-C4H10 into the CO2 stream. An enhanced viscosity reduction of the CO2/heavy-oil system is also achieved in the presence of either C3H8 or n-C4H10. The enhanced swelling effect and viscosity reduction caused by adding either C3H8 or n-C4H10 into the CO2 stream are particularly favorable for achieving a higher heavy-oil recovery compared with pure-CO2 processes. Theoretically, three binary-interaction-parameter (BIP) correlations in the Peng-Robinson (PR) equation of state (EOS) (PR-EOS) method have been proposed for respectively characterizing CO2/heavy-oil binaries, C3H8/heavy-oil binaries, and n-C4H10/heavy-oil binaries by treating each oil sample as a single pseudocomponent with its molecular weight (MW) and specific gravity (SG). The BIP correlations (together with the PR-EOS) can be used to predict the saturation pressures and swelling factors of the C3H8/CO2/heavy-oil system and the n-C4H10/CO2/heavy-oil system with a generally good accuracy.

Quantification of Phase Behavior for Solvent/Heavy-Oil/Water Systems at High Pressures and Elevated Temperatures with Dynamic Volume Analysis

SPE Journal ◽  
2020 ◽  
Vol 25 (06) ◽  
pp. 2915-2931
Author(s):  
Zehua Chen ◽  
Zulong Zhao ◽  
Daoyong Yang
Keyword(s):  
Phase Behavior ◽  
Heavy Oil ◽  
High Pressures ◽  
Elevated Temperatures ◽  
Saturation Pressure ◽  
Water Systems ◽  
Experimental Measurements ◽  
Phase Volume ◽  
Volume Analysis ◽  
Oil Water

Summary Accurate quantification of phase behavior of solvent/heavy-oil/bitumen/water systems at high pressures and elevated temperatures is of high significance for the design of vapor extraction, cyclic solvent injection, expanding-solvent steam-assisted gravity drainage (ES-SAGD), and hot-solvent injection processes. The relevant experimental data and theoretical analyses are still insufficient for achieving a reliable model. This is especially true when the system temperatures approach or exceed the critical temperatures of the solvents used (i.e., when the solvent density is large enough). This study provides new experimental measurements of the phase behavior of propane (C3H8)/carbon dioxide (CO2)/heavy-oil/water systems at pressures up to 20 MPa and temperatures up to 432.3 K. More specifically, four feeds of C3H8/CO2/heavy-oil/water systems are used to conduct constant composition expansion (CCE) tests, during which the heights of the entire fluid system (i.e., total volume) and each phase are recorded at each pressure and temperature, respectively. Theoretically, a dynamic volume analysis (DVA) of the measured data is proposed for the first time to quantify each phase, provided that the assumption for vapor phase is valid and that the vapor and oleic phase densities can be accurately calculated. By tuning the binary interaction parameter (BIP) for solvent/heavy-oil pairs (denoted as BIPS−HO) to match the total volume, the height of the vapor/oleic (V/L) interface can be matched as well. By using the tuned BIPS−HO, the total volume and height of the V/L interface of C3H8/CO2/heavy-oil/water systems can be accurately predicted, no matter whether the solvent solubility in water is low (i.e., C3H8) or high (i.e., CO2). This DVA can be used to determine/evaluate the solvent solubility, saturation pressure/phase boundary, and phase volume/density accurately in a large temperature and pressure range. The newly proposed DVA method is also used to reproduce the experimental measurements collected from the literature, including phase-volume fractions, solvent solubility, and saturation pressure. In addition, the DVA method can serve as a tool to check whether the experimental measurements are reliable or not.

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