Survey interpolation: A software for calculating correct wellpath between survey stations

Abstract

In this Master’s thesis a Microsoft Excel Visual Basic for Applications (VBA) scheme is developed to automatically interpolate and calculate between survey stations. Interpolation techniques of the assumed mathematical model of the Minimum Curvature Method (MCM) are used to determine borehole position by employing measured depth (MD), Inclination and Azimuth as input parameters. Output parameters are Dogleg Severity (DLS) and the 3D coordinates; True Vertical Depth (TVD), Northing (E) and Easting (E). The aim is to compare survey data from continuous near bit inclination (NBI) measured by the Baker Hughes’s AutoTrak tool and survey data from OnTrak tool (MWD). The AutoTrak NBI tool measures inclination continuously while rotating and the OnTrak MWD tool measures directional coordinates usually at 10 – 30 m intervals. By using the measured NBI from the AutoTrak instead of using an interpolated inclination to calculate 3D coordinates between survey stations, especially the TVD, the aim is to compare end survey station interpolations of the MWD survey with the end results obtained utilizing the NBI for calculations. Comparison of the results showed that there is not much difference in calculated end results between NBI and MWD surveys.