| Popis: |
Well integrity is very important for well operation in oil and gas industry. Advanced technologies and analyses have been developed to ensure well integrity. One of the most important analysis to be done is the evaluation of the cement bond which measures the presence and bonding of cement between casing and the formation in a particular depth or interval. This evaluation is critical for hydraulic isolation to withstand subsequent completion and production operation. Usually, Cement bond evaluation is done from wireline logging, with a tool that transmits acoustic waves and compute the acoustic energy propagating through the casing, the cement and the formation. The amplitude and the attenuation of the returned wave can be correlated with Bond Index (BI), due to the difference in acoustic impedance between casing and cement. Over years, different wireline technologies have been developed and matured for cement bond evaluation. Nowadays, it can be found scenarios where wireline operation is not feasible, such as in highly deviated wells or when a quick turnaround is needed. Acoustic technology in Logging While Drilling (LWD) has been developed to measure the compressional and shear slowness of the formation. These devices are able to transmit acoustic wave at different frequencies and receive them after propagation through a medium, applicable in cased hole condition. This paper presents a case study where the LWD Acoustic technology was successfully used to evaluate the cement bond in a high deviated well in Brazil and the results show the capabilities of the technology to generate a qualitative cement bond data quality. These results were successfully validated using sonic and ultrasonic wireline technologies. This comparison, between LWD acoustic and wireline results, is shown in this paper, including details of the methodology applied to the test, parameters considered and the data processing. |
