Jim Carrigan Observatory and directional drilling in Alaska

External field variations, such as those observed in one-minute observatory data are sources of error for magnetic down-hole survey tools used in directional drilling. These tools, which include magnetic probes, are used in measurement while drilling (MWD) methods to monitor the well-bore position and navigate to the planned oil or gas target. Significant deviations from the well plan can be avoided by using measurements from magnetic observatories to correct the surveys. In order to support directional drilling operations in Prudhoe Bay, Alaska, Jim Carrigan Observatory (JCO) was established in 1997 as a joint venture between science and industry and has operated to meet drilling needs ever since. The site was chosen to be as near to the well positions as possible providing the necessary data to combine the measured external field variations with global and crustal field models and thus provide accurate reference values for well-bore surveys in real time. We describe the JCO operations and developments made to help counteract the extreme weather conditions and other difficulties associated with its’ high latitude location. The data processing and quality control procedures required to enable the use of JCO data for real time MWD operations are discussed and examples of their use by industry are shown. We also present a summary of the JCO results since 2003, when the observatory was upgraded to the same standard as the other BGS operated observatories. We discuss the quality of these results and the potential for use of them in scientific studies.