Small-sized drilling microchips become useful and efficient logging devices for distributed downhole temperature and pressure measurement. In this paper, new generation of temperature and pressure microchips are developed. Advanced technologies including micro-size wireless charging and light weight protective material have been used to improve reliability and durability as well as the recovery rate of the microchips. Tests have been conducted both in the laboratory and in the field for evaluation.
During drilling operations, initialized microchips are dropped into the drill pipe while making pipe connections. The microchips travel downwards in the drill pipe and pass through the bit nozzle carried by the mudflow. Then microchips are pushed upwards in the annular section and are eventually recovered at the shale shaker. Distributed downhole parameters such as temperature and pressure measurements are recorded periodically in the memory of the microchip, which can be downloaded entirely after the recovery process.
The lab test result shows the new generation microchip is able to work longer in lower power consumption under simulated extremely harsh conditions. By applying different light weight protective material, microchip can adjust its own density close to the mud density to make it easier for flowing upward in the annular section. This way the microchip recovery rate can be increased in the field. The field test results show an excellent correlation between the measurements and the pump flow rate. The wellbore in-situ temperature profile processed from the microchips could be of significant importance for optimizing cement formulation.
Unlike other downhole measurement method, microchips provide valuable pressure and temperature data in front of the drill bit while drilling. It is an efficient diagnostic tool for identifying problems encountered in drilling process, such as seepage, lost circulation and local overheating. Microchip technology can be considered as an open distributing sensing platform for integrating other sensor units and creating downhole sensor networks, which will be a digital evolution to achieve internet of things (IoT) in oil and gas industry.
