| dc.description.abstract | Mud Pulse Telemetry (MPT) is the standard way of communicating with downhole tools on the Norwegian Continental Shelf today. Wired Drill Pipe (WDP) is a high-speed telemetry alternative to traditional telemetry systems. The WDP technology enables bi-directional data transmission at speeds up several magnitudes larger than mud pulse telemetry. This means getting memory quality downhole data in real time and being able to communicate commands to downhole tools much faster while drilling.
With the search for new oil and gas reservoirs intensifying, the need for downhole information is bigger than ever. While formation logs taken while drilling provide a lot of information, the best way to obtain information about the formation properties is through core analysis. Coring is a time consuming and expensive operation due to low rate of penetration, time spent on tripping and difficulty with obtaining a full core, leading to unplanned runs and extra time. Vibrations and jamming are the main culprits for failure to obtain good core recovery.
This thesis introduces the WDP technology and the possible advantages of such technology. A data analysis has been performed in order to evaluate the value of having real-time, downhole measurements in coring operations. Data was provided from Lundin Norway and National Oilwell Varco (NOV), and consists of eight core runs from an Edvard Grieg exploration well. A Dynamic Drilling Sub, placed in near the bit during coring, recorded the downhole data.
Based on the data provided for this analysis it was found that it was not possible to predict jamming; no trends leading up to the jam were detected and having real-time downhole data did not give an earlier indication of jam than surface parameters alone. The surface parameters were in most cases sufficient to identify jam and correctly decide when to pull the string, but the downhole measurements are beneficial and provide a more accurate picture of downhole events.
Since core jamming is one of the biggest reasons of failure in obtaining good core recovery, part of the focus of the analysis was on identifying jam and jam signatures . A jam signature was identified for Polycrystalline Diamond Compact core heads and a jamming signature was suggested when using diamond impregnated core head. Since only one core was confirmed to have jammed when using impreg core heads it is hard to verify the signature. These signatures can be used to create a warning system for the driller, and prevent the increased amount of data available at surface from creating confusion instead of confidence.
It is definitely an advantage to use WDP in a coring operation, but based on the data analyzed in this thesis it is hard to say if using WDP in coring operations, alone, justifies the cost of implementing the technology. | en |
