Abstract: A method for evaluating saturation of a kerogen bearing subterranean formation includes obtaining conductivity and permittivity values of the formation and providing an effective medium model relating the conductivity and the permittivity to a water filled porosity of the formation and an effective aspect ratio of graphitic kerogen particulate in the formation. The obtained conductivity and the permittivity values are input into the model which is in turn processed to compute the water filled porosity. The method may further optionally include evaluating the water filled porosity to estimate a hydrocarbon producibility of the formation.

Abstract: Methods and systems are provided for investigating a rock sample, in which wideband electromagnetic response data are obtained and processed by inversion in order to determine values for a plurality of parameters of the rock sample. The wideband electromagnetic response data is derived from electromagnetic measurements of the rock sample at frequencies that fall within a wideband of frequencies, wherein the wideband of frequencies includes a low frequency sub-band that is sensitive to conductivity of the rock sample and a high frequency sub-band that is sensitive to the permittivity of the rock sample. In one embodiment, the inversion can employ a wideband model that accounts for two different polarization mechanisms. The wideband model can be used to describe predicted electromagnetic response of the rock sample at frequencies that fall within the wideband of frequencies.

Abstract: Methods are provided for identifying one or more transition characteristics in a hydrocarbon fluid such as asphaltene onset pressure (AOP), bubble point or dew point. A transition characteristic is determined by subjecting the fluid to different pressures or temperatures, conducting NMR tests at the different pressures or temperatures to obtain signals, processing the signals to obtain values of a function of an NMR parameter as a function of pressure or temperature, and analyzing the values to find a discontinuity that identifies the transition characteristic. In embodiments, the NMR parameters may include at least one of a relaxation parameter such as T2 or a T1-T2 ratio, a diffusion parameter and an initial magnetization parameter. In embodiments, dual linear fitting, Bayesian change point detection algorithms, and instantaneous slope analysis may be utilized to analyze the values in order to find a discontinuity.

Abstract: Methods and systems are provided for investigating a rock sample, in which wideband electromagnetic response data are obtained and processed by inversion in order to determine values for a plurality of parameters of the rock sample. The wideband electromagnetic response data is derived from electromagnetic measurements of the rock sample at frequencies that fall within a wideband of frequencies, wherein the wideband of frequencies includes a low frequency sub-band that is sensitive to conductivity of the rock sample and a high frequency sub-band that is sensitive to the permittivity of the rock sample. In one embodiment, the inversion can employ a wideband model that accounts for two different polarization mechanisms. The wideband model can be used to describe predicted electromagnetic response of the rock sample at frequencies that fall within the wideband of frequencies.

Abstract: Methods are provided for identifying one or more transition characteristics in a hydrocarbon fluid such as asphaltene onset pressure (AOP), bubble point or dew point. A transition characteristic is determined by subjecting the fluid to different pressures or temperatures, conducting NMR tests at the different pressures or temperatures to obtain signals, processing the signals to obtain values of a function of an NMR parameter as a function of pressure or temperature, and analyzing the values to find a discontinuity that identifies the transition characteristic. In embodiments, the NMR parameters may include at least one of a relaxation parameter such as T2 or a T1-T2 ratio, a diffusion parameter and an initial magnetization parameter. In embodiments, dual linear fitting, Bayesian change point detection algorithms, and instantaneous slope analysis may be utilized to analyze the values in order to find a discontinuity.

Abstract: A methodology for reservoir understanding that performs investigation of asphaltene instability as a function of location in a reservoir of interest. In the preferred embodiment, results derived as part of the investigation of asphaltene instability are used as a workflow decision point for selectively performing additional analysis of reservoir fluids. The additional analysis of reservoir fluids can verify the presence of asphaltene flocculation onset conditions and/or determine the presence and location of phase-separated bitumen in the reservoir of interest.

Abstract: An improved method that performs downhole fluid analysis of the fluid properties of a reservoir of interest and that characterizes the reservoir of interest based upon such downhole fluid analysis.

Abstract: NMR logging in a wellbore is used to monitor an oil reservoir during oil recovery by miscible displacement. Diffusivity distributions found by NMR logging indicate whether one or two phases are present and composition of residual oil. Operation of the oil recovery procedure may be maintained or modified in response to monitoring of the reservoir.

Abstract: Methods and related systems are described for estimating fluid or rock properties from NMR measurements. A modified pulse sequence is provided that can directly provide moments of relaxation-time or diffusion distributions. This pulse sequence can be adapted to the desired moment of relaxation-time or diffusion coefficient. The data from this pulse sequence provides direct estimates of fluid properties such as average chain length and viscosity of a hydrocarbon. In comparison to the uniformly-spaced pulse sequence, these pulse sequences are faster and have a lower error bar in computing the fluid properties.

Abstract: A methodology for reservoir understanding that performs investigation of asphaltene instability as a function of location in a reservoir of interest. In the preferred embodiment, results derived as part of the investigation of asphaltene instability are used as a workflow decision point for selectively performing additional analysis of reservoir fluids. The additional analysis of reservoir fluids can verify the presence of asphaltene flocculation onset conditions and/or determine the presence and location of phase-separated bitumen in the reservoir of interest.

Abstract: An improved method that performs downhole fluid analysis of the fluid properties of a reservoir of interest and that characterizes the reservoir of interest based upon such downhole fluid analysis.

Abstract: The diffusion coefficients and relaxation times of mixtures of alkanes follow simple scaling laws based on the chain length of the constituents and the mean chain length of the mixture. These scaling laws are used to determine chain sizes in a mixture from the distribution of the diffusion coefficients. These scaling laws can be used to determine the mean chain lengths (or chain lengths) of a sample (alkanes or mixtures of alkanes) and therefore the constituents of the sample.

Abstract: Methods and related systems are described for estimating fluid or rock properties from NMR measurements. A modified pulse sequence is provided that can directly provide moments of relaxation-time or diffusion distributions. This pulse sequence can be adapted to the desired moment of relaxation-time or diffusion coefficient. The data from this pulse sequence provides direct estimates of fluid properties such as average chain length and viscosity of a hydrocarbon. In comparison to the uniformly-spaced pulse sequence, these pulse sequences are faster and have a lower error bar in computing the fluid properties.

Abstract: NMR logging in a wellbore is used to monitor an oil reservoir during oil recovery by miscible displacement. Diffusivity distributions found by NMR logging indicate whether one or two phases are present and composition of residual oil. Operation of the oil recovery procedure may be maintained or modified in response to monitoring of the reservoir.

Abstract: The diffusion coefficients and relaxation times of mixtures of alkanes follow simple scaling laws based on the chain length of the constituents and the mean chain length of the mixture. These scaling laws are used to determine chain sizes in a mixture from the distribution of the diffusion coefficients. These scaling laws can be used to determine the mean chain lengths (or chain lengths) of a sample (alkanes or mixtures of alkanes) and therefore the constituents of the sample.

Abstract: The diffusion coefficients and relaxation times of mixtures of alkanes follow simple scaling laws based on the chain length of the constituents and the mean chain length of the mixture. These scaling laws are used to determine chain sizes in a mixture from the distribution of the diffusion coefficients. These scaling laws can be used to determine the mean chain lengths (or chain lengths) of a sample (alkanes or mixtures of alkanes) and therefore the constituents of the sample.

Abstract: The diffusion coefficients and relaxation times of mixtures of alkanes follow simple scaling laws based on the chain length of the constituents and the mean chain length of the mixture. These scaling laws are used to determine chain sizes in a mixture from the distribution of the diffusion coefficients. These scaling laws can be used to determine the mean chain lengths (or chain lengths) of a sample (alkanes or mixtures of alkanes) and therefore the constituents of the sample.

Abstract: Nuclear magnetic resonance methods for extracting information about a fluid in a rock are described. A system of nuclear spins in the fluid are prepared in a driven equilibrium, and a series of magnetic resonance signals generated from the fluid. The series of magnetic resonance signals is detected and analyzed to extract information about the fluid in the rock.

Abstract: Nuclear magnetic resonance logging methods that detect and analyze a steady state free precession (SSFP) signal are described. In some embodiments, Carr-Purcell-Meiboom-Gill (CPMG) spin echoes are detected along with the SSFP signals. From the SSFP signal, either alone or in combination with CPMG signals, information about a region of an earth formation, such as porosity, bound fluid volume and diffusion, may be extracted.

Abstract: Nuclear magnetic resonance logging methods that detect and analyze a steady state free precession (SSFP) signal are described. In some embodiments, Carr-Purcell-Meiboom-Gill (CPMG) spin echoes are detected along with the SSFP signals. From the SSFP signal, either alone or in combination with CPMG signals, information about a region of an earth formation, such as porosity, bound fluid volume and diffusion, may be extracted.