Patent ID: 8180578

Claim:
A method of analyzing phase transitions of fluid in an oilfield operation of an oilfield, comprising: determining a plurality of phase boundaries of a multi-component multi-phase system based on a plurality of geophysical parameters associated with the oilfield, wherein the plurality of phase boundaries are determined by: determining a first temperature at which a first liquid phase associated with the plurality of phase boundaries transitions by disappearing; determining a second temperature at which a second liquid phase associated with the plurality of phase boundaries transitions by disappearing, wherein the first liquid is present when the second liquid disappears, wherein the second temperature is determined based on the first temperature and is lower than or equal to the first temperature; and determining a third temperature at which a gaseous phase transitions by appearing, wherein the third temperature is determined based on the second temperature and is lower than or equal to the second temperature, wherein determining the first, second, and third temperatures are by using pressure and temperature dependent empirical equilibrium multi-phase mole fraction ratios (K-values) of the multi-component multi-phase system; wherein the plurality of phase boundaries are associated with a liquid oil phase, a liquid water phase, and a gaseous phase, and wherein the plurality of geophysical parameters comprises at least one selected from a group consisting of a mole fraction of a volatile hydrocarbon (vhc) component of oil, a mole fraction of a non-volatile hydrocarbon (nvhc) component of oil, a mole fraction of a non-condensable hydrocarbon (nchc) component of oil, a mole fraction of water, pressure of the fluid, and enthalpy of the fluid, in presence of a non-volatile hydrocarbon (nvhc), setting a phase transition enthalpy for a liquid phase to large number representing infinity; in absence of a non-volatile hydrocarbon (nvhc), setting a phase transition enthalpy for a liquid phase based on a maximum of a determined first value of the first temperature as associated with water and a determined second value of the first temperature as associated with at least one volatile hydrocarbon (vhc) component; predicting an amount of an at least one fluid component in a liquid fluid phase of the multi-component multi-phase system by solving a set of flash equations with a computer processor based on the plurality of phase boundaries; and performing the oilfield operation based on the predicted amount.