Novel Survey Method Using a Rotary Steerable System Significantly Improves the Dynamic Inclination and Azimuth Measurement

摘要

When kicking off at low inclination, static measurement-while-drilling (MWD) surveys are used to confirm the kickoff direction when free of magnetic interference from offset wells. However, as MWD continuous azimuth and inclination measurements have limited accuracy, the directional driller will not have confidence in the kickoff direction with continuous (dynamic) survey while drilling, thus requiring additional static surveys to be made, taking up precious rig time. In a novel continuous survey method used in a particular rotary steerable system (RSS), a six-axis survey was taken continuously, both while drilling and when static, with the survey sensors being housed in the RSS. This algorithm was first verified in a software simulator, and it was subsequently implemented and tested in hardware. The effectiveness of the new measurement method was field tested and compared against MWD static survey points. The field test result from multiple wells shows that the new near-bit continuous azimuth and inclination from the RSS is considerably more accurate than that of the axial MWD continuous measurements at very low inclinations of between 1 and 5 degrees. This unique measurement method has valuable applications, such as low-angle kickoff without using multiple static surveys as the directional driller can use the real-time continuous azimuth and/or toolface to accurately steer the well through crowded offshore platform environments. When drilling out of the shoe, this survey method will allow an accurate kickoff approximately 50 ft earlier than would normally be expected as magnetic interference is cleared, and thus saving the precious rig time needed to kick off. Additionally, the use of a continuous gravity toolface is possible without the need for static surveys, allowing accurate low-side sidetracks to be performed even in areas of high magnetic interference.