A method for monitoring the oleophilic fluid to aqueous fluid ratio of a drilling fluid includes selecting a sample of the drilling fluid that has been recirculated, measuring the NMR response of the sample of the drilling fluid and determining the oleophilic fluid to aqueous fluid ratio of the drilling fluid based at least in part on the NMR response.

A method for partitioning NMR T.sub.1-T.sub.2 data may comprise: identifying modes in NMR T.sub.1-T.sub.2 data from a plurality of samples with a multimodal deconvolution or decomposition with regularized nonlinear inversion; deriving a modal properties vector comprising modal properties for each of the modes; performing a cluster analysis of the modes to identify clusters; assigning a poro-fluid class to the clusters based on one or more of the modal properties of the modes in each of the clusters; and deriving partitioned representations for the clusters based on the cluster analysis.

A method for deriving at least one pore or fluid relaxation parameter and endpoint selected from the group consisting of a longitudinal T.sub.1 pore surface relaxivity constant (ρ.sub.1), a transverse T.sub.2 pore surface relaxivity constant (ρ.sub.2), a pore surface-to-volume ratio (A/V), an equivalent pore-throat radius (r.sub.eq), and a bulk fluid relaxation time (T.sub.B) comprising: identifying modes in NMR T.sub.1-T.sub.2 data; assigning the modes to a poro-fluid class; clustering the modes based on poro-fluid class; estimating T.sub.B based on an asymptote fit of the clusters using T.sub.1 and T.sub.2 relaxation mechanisms in a bulk fluid relaxation-dominated limit; estimating ρ.sub.2/ρ.sub.1 based on an asymptote fit of the clusters using T.sub.1 and T.sub.2 relaxation mechanisms in a surface relaxation-dominated limit; fitting the T.sub.1 and T.sub.2 relaxation mechanisms to the clusters using the estimated T.sub.B; and deriving the pore or fluid relaxation parameter and endpoint for the poro-fluid classes from the fit.

A method and device for detection of solid organic matter and fluids in a shale rock by means of low field Nuclear Magnetic Resonance (NMR) in a single measurement, by submitting a rock sample to a 2D NMR assay comprising applying a 2D pulse sequence with a saturation-recovery, or inversion-recovery, in an indirect dimension and an FID-CPMG in a direct dimension. The method can be used as an analytical technique for rock samples from unconventional hydrocarbon reservoirs.

The application relates to the technical field of oil and gas field development, and discloses a correction method and system for a permeability model considering gas hydrate distribution, and a method and system for determining the permeability of the hydrate-bearing porous medium. The correction method includes: calculating a water mass and a hydrate saturation of each subregion of a porous medium in a dissociation process of a gas hydrate; calculating an average permeability of the porous medium in the dissociation process of the gas hydrate according to the hydrate saturation and a permeability model, wherein a value of a permeability characteristic parameter in the permeability model is an initial value of the permeability characteristic parameter; and determining the initial value of the permeability characteristic parameter as an optimal value of the permeability characteristic parameter under a condition that an difference between the average permeability of the porous medium and an actually measured permeability in the dissociation process of the gas hydrate is less than or equal to a preset value. In the application, through the corrected permeability model, the permeability characteristics of the porous medium considering the heterogeneous distribution of the hydrate can be accurately measured.

A method of evaluating a subterranean formation includes conveying a tool along a borehole. The tool includes a transmitter that transmits a drive pulse and a receiver that receives at least one formation response to the drive pulse. The method further includes calculating a signal-to-noise ratio of the at least one formation response and comparing the signal-to-noise ratio to a programmable threshold. The method further includes determining, based on the comparing, an adjusted drive pulse to transmit and transmitting the adjusted drive pulse. The method further includes and receiving at least one formation response to the adjusted drive pulse and deriving formation data from the at least one formation response to the adjusted drive pulse. The method further includes displaying a representation of the formation based on the formation data.

A method of evaluating a subterranean formation includes conveying a tool along a borehole. The tool includes a transmitter that transmits a drive pulse and a receiver that receives at least one formation response to the drive pulse. The method further includes calculating a signal-to-noise ratio of the at least one formation response and comparing the signal-to-noise ratio to a programmable threshold. The method further includes determining, based on the comparing, an adjusted drive pulse to transmit and transmitting the adjusted drive pulse. The method further includes and receiving at least one formation response to the adjusted drive pulse and deriving formation data from the at least one formation response to the adjusted drive pulse. The method further includes displaying a representation of the formation based on the formation data.

System for detecting explosive substances and drugs by nuclear quadrupole resonance having a central processing unit (UC) which connects to a storage, data processing, and interface unit (USPI) provided with a user console (1C) and a with a head (CS1) for scanning explosives/drugs around the legs and a head (CS2) for scanning suspicious objects on the ground or that cannot be moved having a radio processing system (SPR) which includes a programmable RF signal generator (DDS) which transmits RF pulses to a power amplifier (AP) coupled to an interface for gain control and for the acquisition of the reflected signal level (IAP), a series-parallel tuning circuit (CA) consisting of a flat spiral ferrite-core coil (L) and two variable capacitors (CV1, CV2) driven by two stepper motors (M1, M2) which are controlled by an automatic tuning matching module (WIAA) through control interfaces.

System for detecting explosive substances and drugs by nuclear quadrupole resonance having a central processing unit (UC) which connects to a storage, data processing, and interface unit (USPI) provided with a user console (1C) and a with a head (CS1) for scanning explosives/drugs around the legs and a head (CS2) for scanning suspicious objects on the ground or that cannot be moved having a radio processing system (SPR) which includes a programmable RF signal generator (DDS) which transmits RF pulses to a power amplifier (AP) coupled to an interface for gain control and for the acquisition of the reflected signal level (IAP), a series-parallel tuning circuit (CA) consisting of a flat spiral ferrite-core coil (L) and two variable capacitors (CV1, CV2) driven by two stepper motors (M1, M2) which are controlled by an automatic tuning matching module (WIAA) through control interfaces.

A shale oil analysis method and apparatus for continuously characterizing saturation of adsorbed oil and free oil, comprising: obtain NMR T2 spectrum, NMR porosity, oil saturation and wettability indexes of a core samples, determine a lower limit value for the saturation calculation of the absorbed oil based on the NMR T2 spectrum, the NMR porosity, the oil saturation and wettability indices; determining a lower limit value for the saturation calculation of the free oil according to the bulk relaxation T.sub.2 spectrum of the crude oil of the well interval or an adjacent well interval and the NMR T.sub.2 spectrum of the core samples; calculating the saturation of the absorbed oil and the free oil, and analyzing the shale oil in the well interval to be analyzed. The solution realizes the quantitative and continuous characterization of the adsorbed oil and the free oil of the shale oil via well logs.