ADVANCED LOGGING SYSTEM FOR PRECISE MEASUREMENT OF AIR-FILLED POROSI TY IN GEOLOGICAL FORMATIONS

ACCURATE MEASUREMENTS OF AIR-FILLED POROSITY (AFP) AT DEPTHS IN THE RANGE 200-1000 M ARE REQUIRED TO PRECISELY DETERMINE THE SEISMIC MAGNITUDE OF UNDERGROUND NUCLEAR TESTS. A PROGRAM IS PROPOSED TO: (1) SPECIFY AN APPROACH, USING ONE OR MORE DIAGNOSTICS, FOR MEASURING AFP TO AN ACCURACY OF ONE POROSITY UNIT (1 PU) AND (2) TO DEVELOP A FORMATION DENSITY/LITHOLOGY LOGGING TOOL WHICH WILL FORM A KEY ELEMENT OF THE SPECIFIED MEASUREMENT APPROACH. THE PROPOSED TOOL USES A LINEAR INDUCTION ACCELERATOR (LIA) TO GENERATE A HIGH ENERGY X-RAY BEAM. IT IS SIMILAR TO EXISTING GAMMA-GAMMA LOGGING TOOLS WITH THE FOLLOWING IMPORTANT EXCEPTIONS: (1) THE X-RAY ENERGIES EXTEND UP TO ?4 MEV, THUS FACILITATING MUCH GREATER DEPTHS OF INVESTIGATION; (2) THE STAND-OFF DISTANCE OF THE X-RAY SOURCE AND THE DETECTORS FROM THE BOREHOLE WALL CAN BE SMALLER; (3) THE X-RAY SOURCE WILL HAVE A MUCH HIGHER INTENSITY WHICH HELPS TO INCREASE THE STATISTICAL ACCURACY AND (4) IT DOESN'T CONTAIN RADIOACTIVE MATERIAL, THUS SIMPLIFYING HANDLING AND TRANSPORTATION. THE OVERALL OBJECTIVE OF PHASE I IS TO DETERMINE THE FEASIBILITY OF NEW TECHNIQUES FOR MEASURING AFP TO AN ACCURACY OF 1 PU. THIS OBJECTIVE WILL BE ACCOMPLISHED BY PERFORMING THE FOLLOWING TASKS: (1) EVALUATE NEW AND EXISTING DIAGNOSTICS FOR DETERMINING AFP AND ESTABLISH THE REQUIREMENTS FOR AN IMPROVED APPROACH; (2) DEVELOP THE CONCEPTUAL DESIGN FOR AN EXPERIMENTAL HIGH ENERGY X-RAY TOOL WHICH WOULD BE CONSTRUCTED IN PHASE II AND (3) DEVELOP AND TEST THE KEY PORTION OF THE X-RAY TOOL IN ORDER TO DEMONSTRATE ITS FEASIBILITY. ANTICIPATED BENEFITS/POTENTIAL COMMERCIAL APPLICATIONS - THIS PROJECT WILL PROVIDE AN ADVANCED LOGGING TOOL FOR MEASURING BOTH DENSITY AND LITHOLOGY IN GEOLOGICAL FORMATIONS WITH SUPERIOR DEPTHS OF INVESTIGATION. IT WILL HAVE IMPORTANT APPLICATIONS IN THE PRECISE MEASUREMENT OF AFP ABOVE AND BELOW THE WATER TABLE. IT WILL ALSO HAVE COMMERCIAL APPLICATIONS IN THE LOGGING OF OIL AND GAS WELLS.