Abstract: A method of using a survey system comprising at least one sensor. The method comprises operating the survey system to provide information regarding the orientation of the sensor relative to the Earth at a first resolution level while the sensor is a first distance relative to the Earth's surface and operating the survey system to provide information regarding the orientation of the sensor relative to the Earth at a second resolution level while the sensor is a second distance relative to the Earth's surface. The second distance is larger than the first distance. The second resolution level is higher than the first resolution level.

Abstract: A method of using a survey system comprising at least one sensor. The method comprises operating the survey system to provide information regarding the orientation of the sensor relative to the Earth at a first resolution level while the sensor is a first distance relative to the Earth's surface and operating the survey system to provide information regarding the orientation of the sensor relative to the Earth at a second resolution level while the sensor is a second distance relative to the Earth's surface. The second distance is larger than the first distance. The second resolution level is higher than the first resolution level.

Abstract: A method of using a survey system comprising at least one sensor. The method comprises operating the survey system to provide information regarding the orientation of the sensor relative to the Earth at a first resolution level while the sensor is a first distance relative to the Earth's surface and operating the survey system to provide information regarding the orientation of the sensor relative to the Earth at a second resolution level while the sensor is a second distance relative to the Earth's surface. The second distance is larger than the first distance. The second resolution level is higher than the first resolution level.

Abstract: A method and apparatus are provided for determining an orientation of a drilling tool of a drilling system configured to drill a borehole into the Earth's surface. The method includes providing a survey system including at least one sensor within the drilling system. The sensor is configured to provide orientation information. The survey system is operable at a plurality of resolution levels. The method further includes operating the survey system at a first resolution level while the drilling tool is a first distance relative to the surface. The method further includes operating the survey system at a second resolution level while the drilling tool is a second distance relative to the surface. The second distance is larger than the first distance. The second resolution level is higher than the first resolution level.

Abstract: A method for well borehole survey is set out. A sonde supports X and Y accelerometers and X and & sensors on a rate gyro having a Z axis aligned with the sonde. On a slickline, or within a drill string, the sonde is used to measure four variables, these being G.sub.x and G.sub.y, A.sub.x and A.sub.z. This enables well azimuth and inclination to determined. Measuring depth enables a survey to be made.