Abstract: There is disclosed an apparatus (115) for detecting and/or measuring a downhole feature (195), such as a fluid/fluid interface, in a well (105). The apparatus (115) comprises a first fluid and/or liquid permeable tube (120). The first tube (120) is porous or (micro)perforated. The apparatus (115) comprises a second fluid and/or liquid impermeable tube (130). The first and second tubes (110, 130) are hollow, and therefore, provide first and second waveguides, respectively.

Abstract: There is disclosed a fluid and/or material detection device (2) comprising an electromagnetic transmitter and/or receiver arrangement (4) comprising a cable (6) or transmission line that acts as an antenna (e.g., transmitter and/or receiver). The device (2) comprises a liquid level detection device and/or particulate (particulate containing fluid) detection device. At least a portion of the cable (6) is rigid/stiff, e.g., at least a portion of the cable (6) having a length of from 0.1 meters to 10 meters. The cable (6) advantageously comprises a coaxial cable or triaxial cable, a radiating cable (RC) or a leaky feeder (LF). The device (2) finds use in an enclosed structure (36), e.g., a cased borehole or well, which can be sealed or unsealed during use of the device (6). The enclosed structure (36) provides a space (34), e.g., an annulus between a production tubing and a wellbore casing or a bore of a production tubing.

Abstract: There is disclosed in one implementation a method of or for use in or for detecting, measuring and/or determining at least one variable or characteristic in a space, such as a well, container or vessel. In one implementation the method comprises: 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.

Abstract: A method for use in or for detecting a downhole feature in a well comprises transmitting an electromagnetic signal from a first position located substantially at or adjacent to surface through a first space to the downhole feature. The method further comprises receiving an electromagnetic signal at a second position located substantially at or adjacent to surface after reflection of the transmitted electromagnetic signal from the downhole feature and after propagation of the reflected electromagnetic signal through a second space. The method may comprise sealing the well before transmitting the electromagnetic signal. Such a method may be used to detector determine a distance from surface to a downhole feature such as a fluid interface in a completed production, injection or observation well.

Abstract: There is disclosed an apparatus (115) for detecting and/or measuring a downhole feature (195), such as a fluid/fluid interface, in a well (105). The apparatus (115) comprises a first fluid and/or liquid permeable tube (120). The first tube (120) is porous or (micro)perforated. The apparatus (115) comprises a second fluid and/or liquid impermeable tube (130). The first and second tubes (110, 130) are hollow, and therefore, provide first and second waveguides, respectively.

Abstract: A structure defines an elongate space and comprises an apparatus installed within the structure. The apparatus includes a signal generator and detector arrangement, and at least one antenna coupled to the signal generator and detector arrangement. The at least one antenna is coupled to the elongate space for transmitting an electromagnetic signal into the elongate space and for receiving the electromagnetic signal from the elongate space after reflection of the electromagnetic signal from a feature within the elongate space. The apparatus may be used to monitor the feature within the elongate space.

Abstract: A structure defines an elongate space and comprises an apparatus installed within the structure. The apparatus includes a signal generator and detector arrangement, and at least one antenna coupled to the signal generator and detector arrangement. The at least one antenna is coupled to the elongate space for transmitting an electromagnetic signal into the elongate space and for receiving the electromagnetic signal from the elongate space after reflection of the electromagnetic signal from a feature within the elongate space. The apparatus may be used to monitor the feature within the elongate space.

Abstract: A method for use in or for detecting a downhole feature in a well comprises transmitting an electromagnetic signal from a first position located substantially at or adjacent to surface through a first space to the downhole feature. The method further comprises receiving an electromagnetic signal at a second position located substantially at or adjacent to surface after reflection of the transmitted electromagnetic signal from the downhole feature and after propagation of the reflected electromagnetic signal through a second space. The method may comprise sealing the well before transmitting the electromagnetic signal. Such a method may be used to detector determine a distance from surface to a downhole feature such as a fluid interface in a completed production, injection or observation well.