Open hole formation evaluation logs are not run where the perceived benefits are marginal. In many horizontal wells, the benefits are not fully assessed because cost and/or access difficulties override other considerations. In these cases, sub-seismic lateral variations in reservoir properties can only be inferred - they are rarely measured. Small diameter battery-powered logging tools operating without a wireline have collected high quality data in a broad range of high angle situations. Wireless conveyance techniques are faster and safer than wireline pipe conveyed logging, and have cost, access and data quality benefits over logging while drilling (LWD). Wireless tools have been conveyed in and on drill pipe, on coiled tubing without an electric line, and as part of a modified casing string. The tools can be deployed safely in underbalanced wells.

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