A new generation of a near real-time, cost-effective distributed downhole temperature and pressure measurement system that utilizes improved microchip technology was developed in the laboratory and tested in the field.

The improved microchip technology splits temperature and pressure measurement into two individual systems. Design of the printed circuit board and the electrical components has minimized the measurement error and power comsumption of the system. Significant improvements in the integrity of the drilling microchip have been achieved by using a new protective material. Experimental results show that the accuracy of the system measurement is within ±0.5°C for temperature measurements and ±0.05% for pressure measurements.

The drilling microchip is typically deployed by using a tracer injection system continuously (controlled by a computer) or by dropping it into the drillpipe while making a pipe connection during rig operation. It travels along the inner passage of the drillpipe, exits the bit nozzle, and returns toward the surface in the wellbore annulus because of dynamic circulation with drilling fluid. Then, it is usually captured at the shale shaker at the surface.

A total of 14 new generation tracers were deployed into two different wells in two batches (4 pieces and 10 pieces) during the field evaluations in Saudi Arabia. Nine of the deployed 14 microchips were recovered at the surface with the measurement data stored in the on-chip memory. The results of the field tests proved that the microchip system is able to survive in a well with 13,800ft vertical depth under more than 150°C bottomhole temperature and 10,000 psi bottomhole pressure conditions. Measurements retrieved from the recovered microchips show excellent consistency.

The circulating mud temperature in the field test well has also been predicted by using existing thermal model. The modeling result has been compared to the microchip measurements and it shows a strong agreement between two temperature profiles inside the drillpipe. However, the modeling result is probably not accurate in the annular section based on comparison to the microchip measurements.

The new generation microchip system developed is ready to be deployed in most oilfield conditions to provide a downhole in-situ circulating mud temperature and pressure (i.e., equivalent circulating density) profiles for optimizing cement formulation as well as identifying hole problems such as seepage, lost circulation zones, and open-hole restriction due to poor hole cleaning or an under-gauged hole.

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