Gyrodata Developing a Wireless Gyro-While-Drilling Survey System
Current MWD systems employ magnetic sensors to calculate the direction of downhole drilling assemblies. However, magnetic interference from steel pipe in or around the wellbore can degrade sensor accuracy during certain phases of the drilling operation. When interference is present, the common practice is to run a gyroscopic survey device for an accurate reading, since gyroscopes are not affected by magnetic anomalies.
Typically, several gyroscopic surveys are conducted on electric wireline until the well is free of magnetic interference. Although a highly accurate and effective procedure, the gyro runs take costly time away from the drilling operation and require the added expense of electric wireline. The ideal solution would be a ruggedized gyro probe capable of running in the MWD system while drilling. Survey data would be transferred to surface without a wireline using the MWD telemetry, and drilling would continue uninterrupted.
Gyrodata plans to introduce this first commercial GWD survey system to the drilling industry later this year. Currently undergoing field-tests, the 1 7/8-inch OD by four-foot gyro survey probe is designed to be compatible with the magnetic MWD instrumentation of all of the major suppliers. When required, the GWD probe can be run in a special section contained within the MWD system. Utilizing existing MWD telemetry, such as pulses in the fluid, gyro survey readings can be read at surface in real-time.
The GWD system has numerous applications in standard drilling operations. Magnetic interference from adjacent wells in offshore operations requires gyroscopic surveys in shallow wellbore sections, and gyroscopic readings are always needed in the initial stages of directional, multi-lateral and re-entry drilling projects.
In addition to resolving problems with magnetic interference, gyroscopic surveys are also employed when a higher level of accuracy is required than can be obtained with magnetic sensors under normal conditions. Since the gyroscope is inherently more accurate, the GWD(TM) system should also have broad application in deeper wellbore sections to assure precise wellbore targeting and placement in the reservoir for optimum production.