Abstract: A method and system of monitoring fluid flow in a wellbore. One or more space-distributed temperature input pulses are induced into at least a portion of a fluid in a housing in the wellbore. The housing has at least one cavity and one or more flow ports. A temperature response pulse, caused by the temperature input pulses, are sensed at one or more locations downstream of the cavity and a flow rate of the fluid through the cavity is determined. The flow rate may be determined based on one or more characteristics of the temperature response pulse, and a Retention Time Distribution (RTD) of the cavity.

Abstract: A method and system of monitoring fluid flow in a wellbore (16). One or more space-distributed temperature input pulses (6a,b; 6?; 6?) are induced into at least a portion of the fluid in a housing (15; 15a,b; 15?; 15?) in the wellbore, The housing has at least one cavity (14; 14a,b) and one or more flow ports (4; 4?. 5; 5?; 5a?,b?). A temperature response pulse, caused by said temperature input pulses, are sensed at one or more locations (2) downstream of said cavity (14; 14a,b) and a flow rate of said fluid through said cavity (14) is determined. The flow rate may be determined based on one or more characteristics of said temperature response pulse, and the Retention Time Distribution (RTD) of said cavity.

Abstract: Transducer arrangement for use as receivers in acoustic borehole measurements, in particular for the purpose of geological steering, stratigraphic imaging and control during drilling of deviated and horizontal wells, whereby transducer sensitivity is focused generally in radial directions normal to the drill string axis in close proximity to the drill bit (45). Two separate and substantially similar transducer elements are adapted to be located at substantially the same axial position along the drill string axis. The transducer elements having their output terminals interconnected with opposite polarities, so as to have a combined minimum response to incident acoustic waves and vibrations being identical at both transducer elements.