Acoustic logging based on wellbore resonance
- Mobil R and D Corp., Dallas, TX (United States)
Wellbore resonance phenomena are the basis for a new acoustic logging method, the Stimulated Mode Acoustic Log (SMAL). The SMAL method stimulates a particular mode of wellbore vibration by exciting a resonance for that mode. Specific resonances are excited by driving an acoustic transmitter with a short tone burst of appropriate frequency. SMAL benefits include signal enhancement under adverse conditions, avoiding dispersion effects, propagating formation waves through cased and slotted liner completions, generating steady-state phase and amplitude data, and providing formation Q logs. All of these applications have arisen from studies of wellbore resonance phenomena through well logging and laboratory experiments. One means of study has been the wellbore excitation log, which shows the foot-by-foot response of the wellbore to swept-frequency excitation across the acoustic band. Excitation logs show that resonances are sensitive to lithology and formation saturation conditions. Additional insight has bene provided by generating standing waves under resonance conditions. This approach has led to a means of estimating a formation Q from the decay of standing tube waves. Q data, generated in this way, are consistent with laboratory data for core and quarry samples.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 250832
- Journal Information:
- SPE Formation Evaluation, Vol. 11, Issue 2; Other Information: DN: Paper presented at the 1992 SPE Annual Technical Conference and Exhibition, Washington, DC (US), October 4--7; PBD: Jun 1996
- Country of Publication:
- United States
- Language:
- English
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