Predicting the equilibrium phase behavior of carbon dioxide/hydrocarbon mixtures using a continuous thermodynamic approach

Thesis/Dissertation · Fri Jan 01 00:00:00 EST 1988

OSTI ID:5629754

Angelos, C P

Large-scale compositional reservoir simulations of enhanced oil recovery methods such as the carbon dioxide miscible process must compromise between the number of numerical gridblocks and hydrocarbon components that are utilized in the thermodynamic computations. One solution to this problem is to characterize the heptanes plus (C{sub 7+}) fraction as a continuous statistical distribution in one or more physiochemical variables. The distribution is therefore defined by its mean and variance only, and can be used in Continuous Thermodynamics (CT) models where normal discrete summation calculations are replaced by integral operations. The CT approach was investigated with respect to phase equilibria modeling by cubic equations of state (EOS). Existing EOS a, b, parameter CT expressions correlated to molecular weight (MW) were expanded to bivariate (MW, boiling point) functions for generalized use with paraffin/napthene/aromatic (PNA) mixtures. An experimental P-V-T apparatus was designed and constructed to generate equilibrium data on synthetic oils (C{sub 4}-C{sub 13}) and CO{sub 2} at temperatures of 120 F and 170 F. Experimental pressures ranged from about 800 to 1800 psia. Three different hydrocarbon systems were tested, ranging from an n-paraffins only mixture to a 23 component PNA fluid. Both discrete component/critical property and semicontinuous/MW-boiling point parameter correlation equilibrium flash models were found to do a satisfactory job of reproducing the experimental equilibrium K values and/or distributions of the System 1 data. They also accurately predict the liquid phase compositions of the System 2 and 3 PNA fluids, but overestimate the vapor phase hydrocarbon concentrations by as much as an order of magnitude.

• Research Organization: Wyoming Univ., Laramie, WY (USA)
• OSTI ID: 5629754
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
CARBON DIOXIDE
PHASE STUDIES
CARBON DIOXIDE INJECTION
RESERVOIR ENGINEERING
HYDROCARBONS
OIL WELLS
ALKANES
AROMATICS
BOILING POINTS
ENHANCED RECOVERY
EQUATIONS OF STATE
EQUILIBRIUM
MATHEMATICAL MODELS
MIXTURES
MOLECULAR WEIGHT
PETROLEUM
PRESSURE DEPENDENCE
TEMPERATURE DEPENDENCE
TEST FACILITIES
THERMODYNAMIC MODEL
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
DISPERSIONS
ENERGY SOURCES
ENGINEERING
EQUATIONS
FLUID INJECTION
FOSSIL FUELS
FUELS
MISCIBLE-PHASE DISPLACEMENT
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PARTICLE MODELS
PHYSICAL PROPERTIES
RECOVERY
STATISTICAL MODELS
THERMODYNAMIC PROPERTIES
TRANSITION TEMPERATURE
WELLS
020300* - Petroleum- Drilling & Production