Abstract: A well logging system and method for detecting the presence and estimating the quantity of gaseous and liquid hydrocarbons in the near wellbore zone. The system uses a gradient-based, multiple-frequency NMR logging tool to extract signal components characteristic for each type of hydrocarbons. To this end, a new data acquisition method is proposed in which measurements at different frequencies are interleaved to obtain, in a single logging pass, multiple data streams corresponding to different recovery times and/or diffusivity for the same spot in the formation. The resultant data streams are processed to determine mineralogy-independent water and hydrocarbon saturations and porosity estimates. Gas and oil saturations are used to obtain accurate estimates of the water content, permeability and other parameters of interest.

Abstract: A method for measuring or predicting a property of a porous material while curing, the porous material including therein a liquid which undergoes metamorphosis and which is present in the porous material in different phases during curing, the method including the steps of performing a low frequency, spin-echo nuclear magnetic resonance (NMR) measurement of each phase of the liquid, and correlating the NMR measurement, or extrapolating the property, in accordance with a predetermined relationship between the property and the NMR measurement.

Abstract: Systems and methods for identifying objects which emit signals. Systems and methods described herein utilize fast signal processing techniques which exploit the stable root structure of a signal and extract the eigenvalue of a matrix having a characteristic polynomial which is approximated from an energy spectrum from the object.

Abstract: A method and apparatus is disclosed for efficient processing of nuclear magnetic resonance (NMR) echo trains in well logging. Apriori information about the nature of the expected signals is used to obtain an approximation of the signal using a set of pre-selected basis functions. A singular value decomposition (SVD) is applied to a matrix incorporating information about the basis functions, and is stored off-line in a memory. During the actual measurement, the apparatus estimates a parameter related to the SNR of the received NMR echo trains and uses it to determine a signal approximation model in conjunction with the SVD of the basis function matrix. This approximation is used to determine in real time attributes of the earth formation being investigated.

Abstract: A device and method for rapidly performing automatic magnet shimming using algebraic techniques, based on field maps computed by phase measurement within Carr-Purcell echo sequences. The correction computation for determining shim currents is carried out by a linear programming algorithm which compensates field inhomogeneities within the sample by a linear combination of all the shims. The procedure is non-iterative, thus avoiding instability problems and improving speed performance.