US 12,006,815 B2
Method and system for monitoring a wellbore object using a reflected pressure signal
Artem Valeryevich Kabannik, Novosibirsk (RU)
Assigned to Schlumberger Technology Corporation, Sugar Land, TX (US)
Filed by Schlumberger Technology Corporation, Sugar Land, TX (US)
Filed on Jul. 31, 2020, as Appl. No. 16/944,861.
Claims priority of application No. PCT/RU2019/000537 (WO), filed on Jul. 31, 2019.
Prior Publication US 2021/0032984 A1, Feb. 4, 2021
Int. Cl. E21B 47/095 (2012.01); E21B 43/26 (2006.01); E21B 47/06 (2012.01); E21B 47/18 (2012.01); G01V 1/30 (2006.01); G01V 1/36 (2006.01); G01V 1/50 (2006.01)
CPC E21B 47/095 (2020.05) [E21B 43/26 (2013.01); E21B 47/06 (2013.01); E21B 47/18 (2013.01); G01V 1/307 (2013.01); G01V 1/364 (2013.01); G01V 1/50 (2013.01); G01V 2210/324 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A method of monitoring a position of a wellbore object, comprising:
a) providing at least one pump for performing hydraulic fracturing that causes a pressure signal to propagate along the wellbore and reflect from the wellbore object, thereby creating multiple reflected pressure signals;
b) providing a pressure sensor at a wellhead for registering the reflected pressure signals;
c) preprocessing the reflected pressure signals and pump noise;
d) transforming the reflected pressure signals and the pump noise from a frequency domain into a time-frequency representation with a Short Time Fourier Transform (STFT);
e) computing a pump noise mask by approximating a pump noise signal in the STFT representation with a linear combination of comb shape functions;
f) applying the pump noise mask to the STFT representation of the reflected pressure signals and the pump noise obtained at stage (d) to suppress the pump noise and to obtain a filtered reflected pressure signal;
g) processing the filtered reflected pressure signal and determining a reflection time from the wellbore object; and
h) calculating a depth of the wellbore object from the filtered reflected pressure signals by multiplying the reflection time by a filtered reflected pressure signal propagation velocity.