Recognition of variations in borehole shape in real time drilling allows the drilling engineer to actuate appropriate counteractions to avoid costly failures, or to implement alterations in the drilling practices to optimize the shape of the borehole and thus improve the drilling efficiency.
Developing a high accurate ultrasonic caliper with a special design helps the drilling engineer not only to monitor the wellbore shape and profile but also detecting a kick in real time drilling.
The result of ultrasonic calipers measurement is a 4D image of the borehole, which helps the driller to make proper decisions such as reaming a critical zone, changing the flow rate to reduce erosion or modifying the string rotation speed to reduce vibrations and also detecting a kick when an influx enter to the borehole while drilling.
This paper reviews tests and experiments which have been performed by using high frequency ultrasonic caliper sensor in different drilling fluids and wellbore conditions. A fully automated test robot has been designed which allows vertical and lateral movement as well as rotation of a sensor head in an artificial wellbore for performing the test. Results show that, new design of the ultrasonic caliper increases the accuracy of the measurement by recording the sound velocity in downhole condition.
To simulate the kick condition, pressured air was injected while measuring borehole profile to simulate a kick situation. According to the results, with the special design of the tool it is possible to detect the kick while drilling as well as during wellbore diameter measurement procedure in the downhole condition.