US 12,235,404 B2
Measurement method and apparatus
Sydney Joseph Littleford, Fife (GB)
Assigned to Welldata (Subsurface Surveillance Systems) Ltd., Fife (GB)
Appl. No. 17/642,181
Filed by Welldata (Subsurface Surveillance Systems) Ltd., Fife (GB)
PCT Filed Sep. 10, 2020, PCT No. PCT/EP2020/075410
§ 371(c)(1), (2) Date Mar. 10, 2022,
PCT Pub. No. WO2021/048319, PCT Pub. Date Mar. 18, 2021.
Claims priority of application No. 1913194 (GB), filed on Sep. 12, 2019; and application No. 2000811 (GB), filed on Jan. 20, 2020.
Prior Publication US 2022/0326407 A1, Oct. 13, 2022
Int. Cl. G01V 3/30 (2006.01); E21B 33/00 (2006.01); E21B 47/047 (2012.01); G01V 3/38 (2006.01)
CPC G01V 3/30 (2013.01) [E21B 33/00 (2013.01); E21B 47/047 (2020.05); G01V 3/38 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method for detecting, measuring or determining at least one variable or characteristic in a space, such as a well, container or vessel, the method comprising:
transmitting a first electromagnetic signal from a first position to a feature within the space;
receiving a second electromagnetic signal at a second position after reflection of the transmitted first electromagnetic signal from the feature;
transmitting a third electromagnetic signal from a third position to a calibration feature within the space;
receiving a fourth electromagnetic signal at a fourth position after reflection of the transmitted third electromagnetic signal from the calibration feature;
subsequently transmitting a further first electromagnetic signal from the first position to the feature;
receiving a further second electromagnetic signal at the second position after reflection of the transmitted further first electromagnetic signal from the feature;
transmitting a further third electromagnetic signal from the third position to the calibration feature;
receiving a further fourth electromagnetic signal at the fourth position after reflection of the transmitted further third electromagnetic signal from the calibration feature;
determining the at least one variable or characteristic from a difference or variation in time between the transmission of the first electromagnetic signal and reception of the second electromagnetic signal and the transmission of the further first electromagnetic signal and receipt of the further second electromagnetic signal and a difference or variation in time between the transmission of the third electromagnetic signal and receipt of the fourth electromagnetic signal and the transmission of the further third electromagnetic signal and receipt of the further fourth electromagnetic signal.