Heat-Pulse flowmeter Diagram

Diagram of heat-pulse flowmeter (HPFM) in a borehole. The centralizer centers the tool in the borehole, and the diverter channels flow through the measurement sensors. Fluid flows from the fracture with higher head toward the fracture with lower head, causing vertical flow in the borehole. In the borehole illustrated here, this results in upflow in the borehole.