THE PRIMARY OBJECTIVE OF THIS PROPOSAL IS TO DESIGN AND CONSTRUCT AN ULTRASONIC MEASUREMENT TOOL THAT CAN WITHSTAND DOWNHOLE TEMPERATURES AND PRESSURES IN EXTREME GEOTHERMAL ENVIRONMENTS. PARTICULARLY, THE PROJECT WILL 1) DESIGN HIGH-FREQUENCY HIGHLY-FOCUSED PULSE-ECHO TRANSDUCER AND A PITCH-CATCH TRANSMITTER AND RECEIVERS TO ACCURATELY MEASURE CASING ID, CASING OD, AND CEMENT PROPERTIES; 2) DEVELOP A DEWAR FLASK FOR PROTECTING VULNERABLE INSTRUMENT COMPONENTS; 3) VERIFY THE RELIABLE OPERATION OF THE ELECTRONICS INTEGRATED WITH THE MEASUREMENT SYSTEM IN THE GEOTHERMAL ENVIRONMENTS; 4) BUILD A PILOT TOOL AND DEMONSTRATE ITS CAPABILITY OF OPERATING AT 250°C AND 15,000 PSI FOR 24 HOURS; 5) DEVELOP AN AI-ENHANCED DATA PROCESSING WORKFLOW TO IMPROVE THE ACCURACY OF WELL INTEGRITY EVALUATION.