US 12,359,564 B2
Self-calibrated method of determining borehole fluid acoustic properties
Wei Han, Sugar Land, TX (US); Rocco DiFoggio, Houston, TX (US); and James V. Leggett, III, Magnolia, TX (US)
Assigned to BAKER HUGHES OILFIELD OPERATIONS LLC, Houston, TX (US)
Filed by Wei Han, Sugar Land, TX (US); Rocco DiFoggio, Houston, TX (US); and James V. Leggett, III, Magnolia, TX (US)
Filed on Jun. 13, 2022, as Appl. No. 17/838,801.
Application 17/838,801 is a division of application No. 16/351,145, filed on Mar. 12, 2019, granted, now 11,359,488.
Prior Publication US 2022/0325622 A1, Oct. 13, 2022
Int. Cl. E21B 49/08 (2006.01); G01V 1/50 (2006.01)
CPC E21B 49/08 (2013.01) [G01V 1/50 (2013.01); E21B 49/0875 (2020.05)] 14 Claims
OG exemplary drawing
 
1. A method of determining an acoustic parameter of a downhole fluid using an acoustic assembly comprising a plurality of acoustic reflectors each having at least one acoustically reflective surface at least partially immersed in the downhole fluid, the method comprising:
estimating the acoustic parameter using a value for at least one wave property measured for:
a first near reflection received at a first acoustic receiver (R1) of a first pulse from a first near reflector located a first distance from the first acoustic receiver, the first near reflector having a first impedance value;
a first far reflection received at the first acoustic receiver (R1) of the first pulse from a first far reflector located a second distance from the first acoustic receiver different than the first distance, the first far reflector having a second impedance value;
a second near reflection received at a second acoustic receiver (R2) of a second pulse from a second near reflector located a third distance from the second acoustic receiver, wherein the first near reflector and the second near reflector are physically separate surfaces, the second near reflector has a third impedance value, and the third impedance value is substantially different than the first impedance value;
a second far reflection received at the second acoustic receiver (R2) of the second pulse from a second far reflector located a fourth distance from the second acoustic receiver different than the third distance;
wherein the first pulse, the first near reflection of the first pulse, the first far reflection of the first pulse, the second pulse, the second near reflection of the second pulse, and the second far reflection of the second pulse are each transmitted through the downhole fluid, and wherein estimating the acoustic parameter comprises estimating an acoustic impedance for the downhole fluid based on a first amplitude of the first near reflection, a second amplitude of the first far reflection, a third amplitude of the second near reflection and a fourth amplitude of the second far reflection.