Surface gas correction by group contribution equilibrium model
First Claim
1. A method for characterizing formation fluid, comprising:
- extracting a gas sample from a fluid exposed to a formation during downhole operations;
predetermining a chemical composition of a virgin fluid prior to exposing the virgin fluid to the formation;
exposing the virgin fluid to the formation;
measuring a temperature of the gas sample;
determining from the gas sample a vapor-phase molar contribution of each of one or more components of interest in the fluid exposed to the formation;
determining a partial vapor pressure for each component of interest using the temperature;
determining a liquid-phase molar contribution of each component of interest using the determined partial vapor pressure and the determined vapor-phase molar contribution and a vapor-liquid group contribution equilibrium equation of state; and
subtracting the predetermined chemical composition of the virgin fluid from a sum of the determined vapor-phase and liquid-phase molar contributions of all the components of the fluid exposed to the formation to characterize the formation fluid.
1 Assignment
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Accused Products
Abstract
Methods and systems are disclosed to determine total hydrocarbons from fluid-carrying fluids and solids from a geological formation during downhole operations. Gas extraction at a well site occurs through a gas extractor at a set pressure, detected temperature, detected density, and controlled volume rate. The quantities of various components of interest are determined from samples of fluid influent and effluent from the wellbore by solving a system of equations of state using a group contribution equilibrium model. Knowing approximate chemical compositions of the liquid fluid and solid phases before contamination with formation materials, with the detection of the gas phase and description of the solid phase from the geological formation, allows for determination of total detectable hydrocarbons from geological formations at the surface, and their concentrations to be expressed as mole or mass fraction for materials coming from a wellbore while downhole operations.
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Citations
20 Claims
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1. A method for characterizing formation fluid, comprising:
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extracting a gas sample from a fluid exposed to a formation during downhole operations; predetermining a chemical composition of a virgin fluid prior to exposing the virgin fluid to the formation; exposing the virgin fluid to the formation; measuring a temperature of the gas sample; determining from the gas sample a vapor-phase molar contribution of each of one or more components of interest in the fluid exposed to the formation; determining a partial vapor pressure for each component of interest using the temperature; determining a liquid-phase molar contribution of each component of interest using the determined partial vapor pressure and the determined vapor-phase molar contribution and a vapor-liquid group contribution equilibrium equation of state; and subtracting the predetermined chemical composition of the virgin fluid from a sum of the determined vapor-phase and liquid-phase molar contributions of all the components of the fluid exposed to the formation to characterize the formation fluid. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system for characterizing formation fluid, comprising:
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a virgin fluid that circulates in a downhole fluid circulation system; a gas extractor fluidly coupled to a flow of fluid within a downhole fluid circulation system; a temperature detector coupled to the extractor; a pressure detector coupled to the extractor; gas analyzer that selectively generates an output corresponding to a vapor-phase molar contribution of each of one or more components of interest in the flow of fluid when exposed to a gas sample of the flow of fluid obtained by the gas extractor; and an information handling system coupled to the temperature detector, the pressure detector, and the gas analyzer, the information handling system comprising a processor and memory device containing a set of instructions that, when executed by the processor, causes the processor to; determine a partial vapor pressure for each the component using the temperature of the gas sample; calculate a liquid-phase molar contribution of each the component of interest using the partial vapor pressure and the vapor-phase molar contribution according to a vapor-liquid equilibrium group contribution equation of state; and subtract a chemical composition of the virgin fluid from a sum of the determined vapor-phase and liquid-phase molar contributions of all the components in the flow of fluid to characterize the formation fluid. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A system for characterizing formation fluid, comprising:
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a first extractor fluidly coupled to a fluid circulation system of a borehole in the earth, the first extractor arranged for extracting an effluent gas sample from a fluid effluent exiting the borehole; a first temperature detector coupled to the first extractor for measuring an effluent temperature of the effluent gas sample; a first pressure detector coupled to the first extractor for measuring an effluent pressure of the effluent gas sample; a first gas analyzer coupled to the first extractor and arranged to selectively generate an output corresponding to an effluent vapor-phase molar contribution of each of one or more components of interest in the fluid effluent when exposed to a gas sample of the fluid effluent obtained by the gas extractor; a second extractor fluidly coupled to the fluid circulation system arranged for extracting an influent gas sample from a fluid influent entering the borehole; a second temperature detector coupled to the second extractor for measuring an influent temperature of the influent gas sample; a second pressure detector coupled to the second extractor for measuring an influent pressure of the influent gas sample; a second gas analyzer coupled to the second extractor and arranged to selectively generate an output corresponding to an influent vapor-phase molar contribution of each of one or more components of interest in the fluid influent when exposed to a gas sample of the drilling fluid influent obtained by the gas extractor; and an information handling system coupled to the first and second temperature detectors, the first and second pressure detector, and the first and second gas analyzers, the information handling system comprising a processor and memory device containing a set of instructions that, when executed by the processor, causes the processor to; determine an influent partial vapor pressure for each the component using the influent temperature of the influent gas sample; determine an influent liquid-phase molar contribution of each the component using the influent partial vapor pressure and the influent vapor-phase molar contribution according to a vapor-liquid equilibrium group contribution equation of state; determine an effluent partial vapor pressure for each the component using the effluent temperature of the effluent gas sample; determine an effluent liquid-phase molar contribution of each the component using the effluent partial vapor pressure and the effluent vapor-phase molar contribution according to a vapor-liquid equilibrium group contribution equation of state; and subtract the determined influent vapor-phase and liquid-phase molar contributions of all the components of the fluid influent from a sum of the determined effluent vapor-phase and liquid-phase molar contributions of all the components of the fluid effluent to characterize the formation fluid. - View Dependent Claims (15, 16, 17, 18)
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19. A method for characterizing formation fluid, comprising:
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predetermining a chemical composition of a virgin fluid; extracting an effluent gas sample from fluid of a borehole; determining an effluent liquid-phase molar contribution of each component of the effluent gas sample using a vapor-liquid group contribution equilibrium equation of state; and characterizing formation fluid based upon the effluent liquid-phase molar contribution of each component of the effluent gas sample by subtracting the chemical composition of the virgin fluid from a sum of the determined effluent vapor-phase and liquid-phase molar contributions of all the components of the fluid of the borehole. - View Dependent Claims (20)
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Specification