A BOREHOLE TUBEWAVE DAMPER PROBE FOR HIGH RESOLUTION SEISMICAPPLICATIONS

HIGH RESOLUTION BOREHOLE-TO-BOREHOLE SEISMIC TOMOGRAPHY CAN PROVIDE MUCH OF THE INFORMATION NEEDED TO IDENTIFY SUBTLE OIL RESERVOIR HETEROGENEITIES. TO DATE, MUCH OF THE HIGH RESOLUTION CROSS-WELL RESEARCH HAS INVOLVED THE USE OF FLUID-COUPLED PIEZOELECTRIC SEISMIC SOURCES. HOWEVER, IN PRACTICAL COMMERCIAL APPLICATIONS OF FLUID-COUPLED SOURCES, SOME CONSIDERATION MUST BE GIVEN TO DEPLOYING THE SOURCE IN A MANNER THAT OVERCOMES THE INHERENT PROBLEMS ASSOCIATED WITH A FLUID-COUPLED DESIGN. ONE MAJOR PROBLEM IS THAT A SIGNIFICANT PORTION OF THE ENERGY GOES INTO THE GENERATION OF BOREHOLE TUBEWAVES. THIS ENERGY LOSS RESULTS IN A REDUCED EFFICIENCY OF THE SOURCE. IN GENERAL, TUBEWAVES AREA SIGNIFICANT PROBLEM IN APPLICATIONS INVOLVING EITHER BOREHOLE SOURCES OR RECEIVERS. OFTEN, TUBEWAVES CAN BE SO PROLIFIC IN BOREHOLE ENVIRONMENTS THAT SUPPORT THEIR GENERATION AND PROPAGATION THAT THEY CAN SIGNIFICANTLY MASK THE SEISMIC SIGNALS OF INTEREST. THE CAPABILITY TO SUPPRESS BOREHOLE TUBEWAVES AND/OR CONSTRUCTIVELY CONTROL THIS FLUID ENERGY COULD SIGNIFICANTLY ENHANCE THE SIGNAL-TO-NOISE RATIOS ATTAINABLE IN A VARIETY OF BOREHOLE SEISMIC APPLICATIONS. THE OBJECTIVE OF THIS PROJECT IS TO DESIGN A BOREHOLE TUBEWAVE DAMPER PROBE THAT IS AN EFFECTIVEAPPLICATION OF PROVEN SURGE SUPPRESSION TECHNIQUES EMPLOYED IN OIL FIELD APPLICATIONS FOR MANY YEARS. THIS DESIGN IS BELIEVED TO BE UNIQUE AND IS EXPECTED TO REDUCE TUBEWAVE AMPLITUDES BY AT LEAST 20 DB. THE PROJECT INVOLVES THE CONSTRUCTION OF TWO TUBEWAVE DAMPER PROBES BASED UPON THIS DESIGN. COMPUTER MODELING AND FIELD INVESTIGATIONS OF THESEDEVICES WILL BE DIRECTED TOWARD ASSESSING THE PROBES CAPABILITIES FOR TUBEWAVE SUPPRESSION AND CONTROL. THE PHASE I WORK ALLOWS FOR MINOR DESIGN MODIFICATIONS OF THE PROBES AND SUBSEQUENT TESTING.