Development and Preliminary Acoustic Calibration of an Experimental Platform for Evaluating the Cement–Formation Interface

In cementing operation, the “cement-–rock” interface bonding ability is an important factor affecting the long-term sealing ability of cement sheath, and the evolution mechanism of the interface sealing ability needs to be further studied. However, due to the particularity of the interface transition area, it is difficult to comprehensively analyze the macroscopic acoustic properties, mechanical properties and sealing evolution ability of the interface due to the lack of precise quantitative testing equipment. To solve the above problems, a cement-sheath cementing-interface sealing capability evolution evaluation device was developed, and a laboratory acoustic response accuracy experiment was carried out to form a quantitative evaluation method of cement–formation interface capability. The developed apparatus withstood pressures up to 30 MPa and temperatures up to 150 °C during basic performance testing. The ultrasonic probes were calibrated using standard cylindrical steel specimens, with P- and S-wave measurement accuracies exceeding 95%. Preliminary cement stone–sandstone acoustic calibration was subsequently performed at 17 °C and 9.8 MPa for 9 days, corresponding to the conditions of the selected field interval. Comparison of the normalized laboratory acoustic response with representative field VDL data showed an agreement of approximately 86.8%. These results provide preliminary validation of the basic operational and acoustic measurement capabilities of the developed platform; however, cement stone–rock interfacial behavior under a broader range of temperature and pressure conditions remains to be systematically validated.