Abstract: Low-Frequency Stoneley Energy for Stratigraphic Evaluation

K. K. Hlaing, C. Lemoy, J. P. Maret, Y. Kremer, W. H. Borland, Myint Maw

Conventional sonic measurements of shear and compressional slowness are body waves that travel within the formation and are commonly used for petrophysical analysis of a well. Low-frequency Stoneley waves travel within the well bore and are traditionally used to interpret fractures and formation permeability, usually by analyzing the energy losses and, to a lesser extent, the slowness. We have found that Stoneley energy has been very useful in the identification of vuggy carbonate facies linked to paleokarstic surfaces in the Upper Burman limestone reservoir of Miocene age, in the YADANA gas deposit, offshore Myanmar. One good example is seen in well YAD-1 where the carbonate reservoir has been cored, allowing precise facies and porosity type determination.

Matching Stoneley energy and core description show a striking correlation between loss of energy and vuggy carbonate facies due to karstic diagenetic processes, always in relation with reefal or near reefal facies.

Accordingly, facies interpretation has tentatively been done in the deeper, noncored reservoir zone, where losses of energy are important and considered as indicating karstic influence and the specific environment.

AAPG Search and Discovery Article #90982©1994 AAPG International Conference and Exhibition, Kuala Lumpur, Malaysia, August 21-24, 1994