Simulation and modeling of pressure pulse propagation in fluids inside drill strings

Modern bottom-hole assemblies are equipped with various sensors which measure the geological and directional information of the borehole while drilling. It is very crucial to get the measured downhole information to the surface in real time in order to be able to monitor, steer and optimize the drilling process while drilling. The transmission of the information to the surface is most commonly carried out by coded pressure pulses (the technology called mud pulse telemetry) which propagate through the drilling mud inside the drill string towards the surface. However, hardly any specific experimental research on the hydraulic data transmission can be found in the literature. Moreover, it is essential to use a reliable model/simulation tool which can more accurately simulate the pressure pulse propagation in fluids inside drill strings under various drilling operation conditions in order to improve the performance of the data transmission process. The aims of this study are to develop and test a laboratory experimental setup, a simulation model and a novel method for detecting and decoding of measurement while drilling pressure pulse propagation in fluids inside drill strings. This thesis presents a laboratory experimental setup for investigating the process of data transmission in boreholes by mud pulse telemetry. The test facility includes a flow loop, a centrifugal pump, a positive mud pulser or alternatively a mud siren, pressure transducers at four different locations along the flow loop and a data collection system. Moreover, it includes an “actuator system” for the simulation of typical noise patterns created by the common duplex or triplex mud pumps. This laboratory setup with great capabilities opens the way for testing and developing new concepts for data transmission. A theoretical model using ANSYS CFX11 (Computational Fluid Dynamics (CFD) commercial code) was successfully developed to simulate dynamic pressure pulse transmission behavior in the fluid insid