Along-well measurements can provide important information about well conditions such as the presence of cuttings beds, washed out zones and gain/loss zones. However, such measurements are sparse at best. Although the introduction of high-speed telemetry and distributed sensors in drilling have helped in that respect, there are currently no methods of extracting data along the complete wellbore while drilling.
The micro-sonde (μSonde) well logging system is a concept for obtaining along-well measurements of temperature, accelerations and pressure while drilling. The μSondes are miniature, self-contained measurement devices. They are suitably designed as sphero-cylinders with a density close to the drilling fluid, such that they can be transported with the fluid flowing from the bottom to the top of the well. The μSondes are carried into the well as a part of the bottom hole assembly (BHA). Multiple μSondes are contained in a storage magazine and are released into the return mud flow for transport to surface. During the transportation through the well, the μSondes will be exposed to the ambient conditions of the drilling fluid, such as accelerations, pressure and temperature. During the flight, the sensors record parameters of interest that describe the well condition. Once the μSonde reaches surface, the recorded data can be analysed to determine the status of the well.
Post-processing of the data requires knowledge of the forces acting on the μSonde and the resulting trajectories from the release point at the BHA and to surface. The objective of the studies presented is to understand the μSonde motion in the drilling fluid.
This project has been coordinated by IRIS (now NORCE) and SINTEF has been partner in the project with the main responsibility for the development of the µSondes.