Horizontal well surveying
High inclination wells (above 70°) and specially horizontal wells have specific difficulties for obtaining accurate surveys. Two main problems arise with high inclination surveying:
- getting wireline survey tools down;
- vertical position uncertainty.
Another application with horizontal wells where surveying is a problem is with dual horizontal wells. With dual horizontal wells, two closely spaced parallel wells are drilled. In addition to the two above problems, magnetic interference from the casing of the first well while drilling the second well will preclude the use of conventional magnetic surveying techniques . . .