US 11,054,540 B2
Computer implemented method for measurement of hydrocarbon content of tight gas reservoirs
Jinhong Chen, Katy, TX (US); Stacey M Althaus, Houston, TX (US); Daniel T Georgi, Houston, TX (US); and Hui-Hai Liu, Katy, TX (US)
Assigned to Saudi Arabian Oil Company, Dhahran (SA)
Filed by Saudi Arabian Oil Company, Dhahran (SA)
Filed on Dec. 17, 2019, as Appl. No. 16/716,900.
Application 16/716,900 is a division of application No. 15/268,022, filed on Sep. 16, 2016, granted, now 10,557,962.
Prior Publication US 2020/0124761 A1, Apr. 23, 2020
This patent is subject to a terminal disclaimer.
Int. Cl. G01V 3/32 (2006.01); G01N 24/08 (2006.01); E21B 49/00 (2006.01); E21B 49/02 (2006.01); E21B 49/08 (2006.01); G01R 33/44 (2006.01)
CPC G01V 3/32 (2013.01) [E21B 49/02 (2013.01); E21B 49/08 (2013.01); G01N 24/081 (2013.01); G01R 33/448 (2013.01); Y02A 90/30 (2018.01)] 5 Claims
OG exemplary drawing
 
1. A non-transitory computer implemented method of 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, the computer implemented method comprising the steps of:
(a) obtaining without measuring porosity the nuclear magnetic resonance relaxation time spectra from the pressurized subsurface tight gas formation in situ at the depth of interest by lowering a sonde containing the nuclear magnetic resonance well logging system by a wireline cable into the well;
(b) forming a measure of the fluid content in the pressurized subsurface tight gas formation based on the obtained nuclear magnetic resonance relaxation time spectra from the nuclear magnetic responses of the pressurized subsurface tight gas formation;
(c) obtaining nuclear magnetic resonance relaxation time spectra from nuclear magnetic resonance measurements of a sample of pure drilling mud for the well obtained at the earth surface, the obtained nuclear magnetic resonance relaxation time spectra indicating water content of the pure drilling mud for the well;
(d) obtaining nuclear magnetic resonance relaxation time spectra from nuclear magnetic resonance measurements of a sample of well fluid brought to the earth surface and containing the pure drilling mud and formation drill cuttings from the well, the obtained relaxation time spectra indicating water content of the obtained sample of the well fluid;
(e) forming a measure of water content in the obtained formation drill cuttings based on the obtained nuclear magnetic resonance relaxation time spectra of the obtained sample of the well fluid; and
(f) determining the hydrocarbon gas content of the pressurized subsurface tight gas formation from the formed measure of the water and hydrocarbon fluid content in situ of the pressurized subsurface tight gas formation and the formed measure of the water content at the earth surface in the obtained formation drill cuttings.