US 11,719,843 B2
Determining a vertically transverse isotropy (VTI) anisotropy along a horizontal section of a wellbore drilled into a formation
Stephen Allan Horne, Haywards Heath (GB)
Assigned to CHEVRON U.S.A. INC., San Ramon, CA (US)
Filed by CHEVRON U.S.A. INC., San Ramon, CA (US)
Filed on Apr. 6, 2020, as Appl. No. 16/840,551.
Claims priority of provisional application 62/830,988, filed on Apr. 8, 2019.
Prior Publication US 2020/0319360 A1, Oct. 8, 2020
Int. Cl. G01V 1/50 (2006.01); G01V 1/30 (2006.01); G01V 5/12 (2006.01); G01V 11/00 (2006.01)
CPC G01V 1/50 (2013.01) [G01V 1/306 (2013.01); G01V 5/12 (2013.01); G01V 11/002 (2013.01); G01V 2210/47 (2013.01); G01V 2210/626 (2013.01)] 22 Claims
OG exemplary drawing
 
1. A method of determining a vertically transverse isotropy (VTI) anisotropy along a horizontal section of a wellbore drilled into a formation, the method comprising:
placing a sonic logging tool downhole in the horizontal section of the wellbore drilled into the formation;
receiving seismic waves at the sonic logging tool placed downhole in the horizontal section;
measuring compressional slowness (DTCO) of the seismic waves using the sonic logging tool placed downhole in the horizontal section and determining an elastic constant C11 of the horizontal section using the compressional slowness (DTCO) and density log data measured in the horizontal section;
measuring vertically polarized shear slowness (DTSV) of the seismic waves using the sonic logging tool placed downhole in the horizontal section and determining an elastic constant C44 of the horizontal section using the vertically polarized shear slowness (DTSV) and the density log data measured in the horizontal section;
measuring horizontally polarized shear slowness (DTSH) of the seismic waves using the sonic logging tool placed downhole in the horizontal section and determining an elastic constant C66 of the horizontal section using the horizontally polarized shear slowness (DTSH) and the density log data measured in the horizontal section;
determining an elastic constant C33 of the horizontal section by determining a vertical compressional slowness of the horizontal section using a model with a condition, wherein the model is built using sonic log data and second density log data of a vertical wellbore drilled into the formation, and wherein the sonic log data of the vertical wellbore comprises shear slowness (DTS) measured in the vertical wellbore and compressional slowness (DTCO) measured in the vertical wellbore, and wherein the condition is that the shear slowness (DTS) of the vertical wellbore is equal to the vertically polarized shear slowness (DTSV) of the horizontal section;
determining a VTI anisotropy along the horizontal section using the elastic constants C11, C44, C66, and C33 of the horizontal section; and
performing seismic imaging, fracturing simulation, a fracturing process, or any combination thereof based on the determined VTI anisotropy along the horizonal section.