Abstract: Salvaging Dipmeters Using an Oil Field "Dinosaur"

Anita R. P. Breimayer, Laura Bigley Puzio

Although state-of-the-art methods such as 3-D seismic and formation imaging tools are widely used, the advantages of the old standard dipmeter should not be dismissed.

Seismic dip is subject to velocity errors, and formation imagers cannot be run in all borehole conditions. The dipmeter offers a relatively low cost, highly effective alternative for defining geologic features.

The 60^Prime=100^prime scale playback of the raw dipmeter data may be an oil field "dinosaur," but it is also the key to assessing the reliability of a dipmeter. This playback should be used to determine CORRELATION QUALITY, critical to the accuracy of any dipmeter. Computer computation of the raw dipmeter data does not always yield reliable dip information, particularly when dipmeters are run under adverse hole conditions or in complex geology. This data can be often salvaged by optical correlation of the 60^Prime playback -- the process of manually correlating raw dipmeter resistivity curves to determine the attitude of bedding planes in the subsurface. Problems such as tool noise, tool pulls, and poor pad contact compromise data quality. These problems can be recognized and compens ted for using optical correlation. Finally, at the 60^Prime scale many formation textures and structural characteristics visible on the formation imaging logs are also discernible on the standard dipmeter traces.

We will offer many Gulf Coast examples and some hands-on demonstrations using the 60^Prime data, and show improved tadpole plots which result from optical correlation.

AAPG Search and Discovery Article #90950©1996 AAPG GCAGS 46th Annual Meeting, San Antonio, Texas