DESIGN AND INITIAL FIELD-TEST RESULTS OF A NEW PULSEDNEUTRONLOGGING SYSTEM FOR CASED RESERVOIRCHARACTERIZATION

摘要

The state-of-the-art in pulsed-neutron surveillanceis constantly challenged by the many and variedwellbores and formations encountered. Pulsedneutron systems are routinely applied todetermine Sigma and Carbon/Oxygen saturations,reservoir porosity, though-casing density,lithology, gas-detection, and water flow. Tooptimize the system design given these manyparameters a new pulsed-neutron system has beendeveloped that utilizes an array of fourLanthanum Bromide (LaBr_3) detectors built into a1.6875-inch O.D. array. Beyond exceptionalpeak resolution, high speed and high temperatureperformance, these higher density halide detectorsare shown to provide incremental improvement toC/O response.Given a high-performance detector array andneutron generator, the next concern was design ofhigh-throughput pulse processors. The pulseprocessors utilize a proprietary digital-filteringand pulse-height algorithm and the operationalperformance is demonstrated both in terms ofthroughput and peak resolution.Tool specific calibrations and operatingparameters are stored in non-volatile memory inthe tool; in this manner the system can beautomatically configured. Demonstrations ofmeasurement precision, calibration, and dataquality control are shown via laboratory and fieldtests.The field-test data also demonstrates howthe system operation is configured for a specificanalysis mode.