Effect of In-Drilling Alignment with General Dynamic Error Model on Azimuth Estimation

Directional drilling is common in oil and natural gas extraction, offering numerous advantages. However, directional drilling requires accurate trajectory measurements. Azimuth is a critical part of the trajectory measurement, but industry standard methods of determining azimuth have drawbacks. Inertial navigation systems (INS) have been proposed as a solution but require periodic calibration. In-drilling alignment (IDA) is a calibration method which uses measured motion of the inertial measurement unit (IMU) to overcome the observability problems that come with a static calibration. This paper presents a novel model which converts IDA motion and inertial measurements into an azimuth estimate. The model is validated using a device designed to carry out IDA under laboratory conditions.