| 摘要 |
A tracer system can monitor in real-time the propagation of a fracture through a rock formation traversed by a well borehole, during hydraulic fracturing processes. The inventive system permits continuous measurement of the movement of gamma-emitting tracers in the fracturing fluid, while the fluid is pumped into the formation. The tracers are injected into the fluid from downhole-placed exploding charges. The fracturing fluid with the tracers passes through perforated production casing into the induced formation fracture, and the tracers emit characteristic gamma radiation. Multiple sodium-iodide scintillometer detectors, arrayed on the logging tool above and below the neutron source, are calibrated to detect the characteristic energy spectra emitted from the activated radioactive tracer isotopes in the fractured formation through the formation rock and the steel production casing and tubing. The detectors pass data to a surface computer system by wireline logging cable or telemetry, allowing graphical display of fracture propagation at the wellsite while the fracturing treatment proceeds. The system allows the operator to control fracture propagation in response to present conditions, preventing "out of zone" fracturing, which can ruin a well. The system helps operators to maximize production while preventing economic waste.
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