Abstract: A method for determining a hydrocarbon concentration from drilling fluid includes pumping the drilling fluid into a wellbore and circulating a sample of the drilling fluid uphole from the wellbore so that ?13C isotopic signatures can be determined for one or more hydrocarbon components and for methane in the sample where the methane includes natural methane originating from the earth formation and artificially-produced methane caused by drill bit metamorphism (DBM). A processor is adapted to determine the concentration of the natural methane in the sample based in part on the ?13C isotopic signatures which may be performed during the drilling of the wellbore.

Abstract: A method of monitoring a subterranean operation includes sampling fluid from a borehole during the operation, and estimating, in near real time, a concentration of one or more gases in the sampled fluid and an isotope composition of the sampled fluid. The method also includes identifying an operational inefficiency in the operation based on the isotope composition associated with the one or more gases, and performing, during the operation, at least one of: alerting an operator and adjusting an operational parameter of the operation, based on identifying the operational inefficiency.

Abstract: A method for determining a hydrocarbon concentration from drilling fluid includes pumping the drilling fluid into a wellbore and circulating a sample of the drilling fluid uphole from the wellbore so that ?13C isotopic signatures can be determined for one or more hydrocarbon components and for methane in the sample where the methane includes natural methane originating from the earth formation and artificially-produced methane caused by drill bit metamorphism (DBM). A processor is adapted to determine the concentration of the natural methane in the sample based in part on the ?13C isotopic signatures which may be performed during the drilling of the wellbore.

Abstract: A method of monitoring a subterranean operation includes sampling fluid from a borehole during the operation, and estimating, in near real time, a concentration of one or more gases in the sampled fluid and an isotope composition of the sampled fluid. The method also includes identifying an operational inefficiency in the operation based on the isotope composition associated with the one or more gases, and performing, during the operation, at least one of: alerting an operator and adjusting an operational parameter of the operation, based on identifying the operational inefficiency.

Abstract: A method for generating a phase envelope log to characterize a subsurface formation includes drilling the borehole with a drill string, circulating a drilling fluid in the borehole, drawing a fluid sample representing a fluid contained in the subsurface formation, estimating a PVT parameter indicative of an in-situ condition of the subsurface formation from the drawn fluid sample, determining at least two phase envelopes at different depths using the estimated PVT parameter, and creating a phase envelope log formed of a continuous series of phase envelopes using the phase envelopes. A related system includes a drill string, a fluid sampling system, and a processor that estimates a PVT parameter indicative of an in-situ condition of the subsurface formation, determines at least two phase envelopes at different depths using the PVT parameter, and creates the phase envelope log.

Abstract: A method of analyzing formation fluids includes introducing a fluid sample into a chromatograph system, passing the fluid sample through a pre-column including a polar column member and a apolar column member in a first flow direction, separating polar constituents from the fluid sample in the pre-column forming an analytical fluid, passing the analytical fluid through a main column of the chromatograph system, and analyzing the analytical fluid in the main column.

Abstract: A method for evaluating a formation fluid includes the steps of drilling a borehole intersecting a formation with a drill string, circulating a drilling fluid in the wellbore, selectively liberating a formation fluid from the formation, injecting the liberated fluid into the drilling fluid returning to the surface, drawing a sample of the returning drilling fluid at the surface, and estimating at least one parameter of the drawn sample at the surface.

Abstract: A method for generating a phase envelope log to characterize a subsurface formation includes drilling the borehole with a drill string, circulating a drilling fluid in the borehole, drawing a fluid sample representing a fluid contained in the subsurface formation, estimating a PVT parameter indicative of an in-situ condition of the subsurface formation from the drawn fluid sample, determining at least two phase envelopes at different depths using the estimated PVT parameter, and creating a phase envelope log formed of a continuous series of phase envelopes using the phase envelopes. A related system includes a drill string, a fluid sampling system, and a processor that estimates a PVT parameter indicative of an in-situ condition of the subsurface formation, determines at least two phase envelopes at different depths using the PVT parameter, and creates the phase envelope log.

Abstract: A method for evaluating a formation fluid includes the steps of drilling a borehole intersecting a formation with a drill string, circulating a drilling fluid in the wellbore, selectively liberating a formation fluid from the formation, injecting the liberated fluid into the drilling fluid returning to the surface, drawing a sample of the returning drilling fluid at the surface, and estimating at least one parameter of the drawn sample at the surface.