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AssigneeSaudi Arabian Oil Company
InventorsJinhong Chen, Stacey M Althaus, Daniel T Georgi, Hui-Hai Liu
Estimating the term…
Nuclear magnetic resonance (NMR) well logs are obtained from a well in the reservoir measures of the total fluid, including both water and hydrocarbon, in the shale of the reservoir. NMR measurement at the surface of shale subsurface samples obtained in the form of drill cuttings or core samples from the same well provide measures of total water content of the shale. At the surface, pressure on the subsurface sample becomes that of atmospheric pressure, and hydrocarbon gas contained in the shale cuttings bleeds off. The remaining fluid within the shale cuttings is then only water, which can be measured using NMR techniques. Compensation for the effect of drilling fluids (drilling mud) on the NMR measures from the fluid cuttings is also performed. The hydrocarbon gas content of the formation shale can be determined from the difference between formation NMR well log readings and NMR measurements from subsurface sample.
A data processing system for determining hydrocarbon gas content of a pressurized subsurface tight gas formation at a depth of interest in the earth adjacent a well, the well having therein well fluids comprising drilling mud and formation drill cuttings containing drilling mud, the hydrocarbon gas content being determined from nuclear magnetic resonance relaxation time spectra obtained in situ from the pressurized subsurface tight gas formation and indicating water and hydrocarbon fluid content in the pressurized subsurface tight gas formation, the relaxation time spectra being obtained by a nuclear magnetic resonance well logging system comprising a sonde lowered by a wireline cable into the well to obtain without measuring porosity the nuclear magnetic resonance relaxation time spectra, the data processing system comprising:
Dependencies are inferred from the claim text.