Investigating depth structure uncertainty for horizontal well placement, Bauer Field, Cooper-Eromanga Basin

Abstract

The Bauer Field was discovered in August 2011 on the Western Flank of the Cooper-Eromanga Basin. Bauer 1 discovered an 11 m oil column in the Namur Sandstone, directly overlain by a 4 m oil column in the McKinlay Member. The Bauer Field has been developed by vertical wells targeting the high deliverability Namur Sandstone with the McKinlay Member as a secondary target. In 2017 the decision was made to specifically target the McKinlay Member with a horizontal well, requiring a multi-disciplinary approach to combine geological, geophysical and engineering datasets. The McKinlay Member is 3–5 m in thickness and below seismic resolution with the wavelet being dominated by the larger acoustic impedance contrast produced from the Namur Sandstone. The McKinlay Member depth structure was mapped using various depth conversion methods to investigate the uncertainty in the depth structure expected for the landing of the well and along the lateral section. An average depth surface generated from the different techniques was useful for providing the general form of the structure and was used to predict dip changes along the lateral section. Understanding the uncertainty led to successful well placement of the first horizontal well in the McKinlay Member on the Western Flank.