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In this paper, we report first acoustic communications experiments along deep drill strings enabling data rates up to 20 kbit/s. To reduce costs for geothermal energy, search for water-bearing fault zones in the rocks hundreds of meters below the ground will be assisted by seismic prediction while drilling (SPWD) enabling control of the drilling direction. The SPWD tool needs higher data rates to the ground. In contrast to common mud-pulse telemetry offering few bit/s, our approach is based on acoustic wave propagation along the steel wall of the drill string. Based on waveguide theory, we develop a tractable channel model for drill-string communication predicting the pass-and stop-bands created by regular screw joints between the pipes. For data transmission, we use closed-loop adaptive orthogonal frequency-division multiplexing (OFDM) following the 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE). First results indicate that, in this way, much highe r data rates can be realized in future deep drilling applications

For reducing costs in drilling technology, seismic prediction while drilling (SPWD) is envisioned. SPWD needs a fast data link bringing up the seismic data from bottomhole to the ground. In this paper, we propose a flexible and easy-to-use acoustic channel model for long drill strings. The model enables efficient design of adaptive OFDM communication links and prediction of achievable data rates for variable string dimensions. We describe acoustic wave propagation by the S-parameters of the drill string modelled as a series of alternating short and long resonators due to segments of constant acoustic impedance. All segments have been parametrised and the final channel is a concatenation of all its segments. We verify the new model by comparison with measurements on a 55 m long drill string. By using our model, the properties of a manifold of real drill pipes with variable dimensions can be predicted. We investigate the impact of length variations typical for rough drilling applications. For efficient communications over 1.5 km, length variations of the screwed tool joints should be limited to a few centimetres while the pipe length may vary up to one meter

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