Evolution in Reliability of High-Speed Mud Pulse Telemetry

摘要

Mud pulse telemetry (MPT) is the leading real-time data transmission technology in the oil industry torndeliver answers while drilling. New logging-while-drilling (LWD) tools produce increasing amounts ofrndata that has to be transmitted to the surface. To avoid a compromise between rate of penetration (ROP)rnand log density, the real-time data rate has to increase. This is particularly true when demanding mudrnenvironments create demanding transmission conditions for MPT. As the well depth increases, it affectsrnthe mud density and mud plastic viscosity, making the situation even more challenging.rnThis paper describes evolutionary changes to a MPT system. The system uses a special trainingrnsequence (TS) that is regularly sent by a shear valve pulser. Surface controls detect the TS and use it torntune, automatically, adaptive filters. These filters respond to the current channel conditions, enablingrnreliable physical data rates of 10bit/s and greater. To avoid decreasing the decoding quality due tornnon-optimal filters that have been calculated during pressure/flow disturbed transmission, the systemrnautomatically tests the performance of all filter sets. Afterwards, the coefficients are saved into a databasernwith additional information. This empowers the field service engineer to perform a quick look at therndatabase and maintain high decoding quality.rnSophisticated changes to the TS and to the surface algorithms have significantly improved thernautomated detection rate of the TS search. Compared to offset runs in challenging fields, decoding qualityrnand reliability have improved. The introduction of higher automation levels enables field personnel torndeliver more answers to the operator, and provide multifaceted bottomhole assemblies with many LWDrnservices. By eliminating the tradeoff between ROP and log density through higher data rates in MPT, thernoverall cost of drilling wells decreases without compromising safety.