Localities of ID-74 to DGN95 Coordinate Transformation Parameters

Abstract As can be referred to almost all regulation in Ministry of Energy and Mineral Resources, all spatial information used in the oil and gas industry in Indonesia, should be referenced to DGN95. While it seems that the datum is now deprecated, the use of DGN95 in many data, especially seismic data collected in 1970 to 1990 are still used and maintain in many companies to avoid huge data transformation work if it is applied nationwide. Some work in finding coordinate transformation has been done since early 2000, but it produces a different set of parameters. In this paper, we collect some published ID74 to DGN95 coordinate transformation parameters and compare to our own results. We measure 20 common points on oil and gas fields using the GNSS method. However, only three points were found consistent and suitable to be the common points. Using the Molodensky-Badekas method, we generate a set of coordinate transformation parameters to be used in the fields. There are 10 parameters to be estimated, three translations, three rotations, one scale and coordinate of center if rotation parameters. Again, there are discrepancies between our results and other published parameters. This shows that the transformation parameters are usually exclusive to the field or region. Our study suggests that coordinate transformation parameters are best to calculate for each specific concession area.