US 11,892,590 B2
Tight reservoir fluid characterization by using sonic slowness well logs
Mohamed Amine Haceb, Dhahran (SA)
Assigned to Saudi Arabian Oil Company, Dhahran (SA)
Filed by Saudi Arabian Oil Company, Dhahran (SA)
Filed on Feb. 11, 2021, as Appl. No. 17/173,360.
Prior Publication US 2022/0252756 A1, Aug. 11, 2022
Int. Cl. G01V 1/50 (2006.01); G01V 5/12 (2006.01); G01N 33/24 (2006.01); G01V 5/10 (2006.01); E21B 49/00 (2006.01); E21B 49/08 (2006.01); E21B 49/02 (2006.01); G01N 24/08 (2006.01)
CPC G01V 5/12 (2013.01) [E21B 49/00 (2013.01); E21B 49/02 (2013.01); E21B 49/087 (2013.01); G01N 24/081 (2013.01); G01N 33/24 (2013.01); G01V 5/10 (2013.01); E21B 2200/20 (2020.05)] 18 Claims
OG exemplary drawing
 
1. A computer-implemented method to improve a computational accuracy and a computation time for predicting a fluid type within an unconventional tight reservoir, the computer-implemented method comprising:
accessing a plurality of measurement logs encoding measurements taken from more than one well location of the unconventional tight reservoir, wherein the plurality of measurement logs comprise a neutron log, a gamma ray (GR) log, a log of bulk density, a log of sonic slowness, a log of resistivity, and a log of photoelectric measurements;
in response to determining that a measured resistivity from the log of resistivity exceeds 31.62MΩ, determining, based on the plurality of measurement logs, a plurality of parameters that characterize a corresponding set of reservoir properties without determining an elastic rock property or a seismic velocity at the more than one well location of the unconventional tight reservoir;
based on a portion of the plurality of parameters, calculating a compressional formation slowness and a shear formation slowness at the more than one well location of the unconventional tight reservoir; and
predicting the fluid type at the more than one well location of the unconventional tight reservoir based on combining a ratio of the compressional formation slowness and the shear formation slowness with at least one of the plurality of parameters such that the fluid type is classified into one of two or more distinct categories and a production of hydrocarbon at unconventional tight reservoir is adjusted according to the classified fluid type, wherein the unconventional tight reservoir is characterized by the measured resistivity exceeding 31.62MΩ.