oa Memory Cross-Dipole Sonic Tool and Novel Deployment Techniques

Cross-dipole sonic data has broad applications in geophysical, petrophysical and geomechanical<br>studies. The advent of the small-diameter memory cross-dipole tool improves operational efficiency in<br>a broad range of well types. The tool combines monopole and cross-dipole acquisition capabilities. It<br>extends the availability of high-quality cross-dipole data to slim and/or high dogleg wells, and reduces<br>acquisition risk in high angle wells and wells drilled through formations prone to borehole bridging. In<br>spite of the tool’s small size and weight, its novel design provides data quality that matches that of<br>previous generation tools. It is deployed with or without a wireline, and is not constrained by wireline<br>data transmission rates because data is recorded to internal memory. Deploying the tool inside drill<br>pipe on the well shuttle facilitates access into highly deviated wells and past bad hole conditions. This<br>versatility makes cross-dipole data available in a far wider range of wells than has previously been possible.<br>Operations have been conducted in diverse logging environments around the world, covering a range<br>of borehole sizes and formation velocities. Comparisons with standard cross-dipole tools have<br>demonstrated benefits in respect of well access. The data has been used in velocity calibration,<br>amplitude variation with offset, shear seismic interpretation, anisotropy, Stoneley permeability, rock<br>strength, and hydraulic fracture design.