Reducing drilling risk using advanced depth imaging: A land case study

Abstract

Accurately positioning wells with respect to faults is critical. This is especially true for appraisal or development wells. Depending on the reservoir structure, wells may need to be as close as feasibly possible to faults. In such situations, the imaging and positioning of the faults are the key success factors and they rely heavily on the quality of the seismic imaging and interpretation. We found out how advanced depth imaging on a land data set leads to reduced drilling risk by improving the lateral positioning of the faults. We will use a real example of a well that was positioned using a legacy narrow-azimuth data set image and unexpectedly reached a fault. We will explain how using full-azimuth data and updating the depth-velocity model produces a prestack depth-migrated (PreSDM) image that gives a more accurate interpretation of the fault. A postmortem analysis of the well indicates that using interpreted horizons and faults from the new PreSDM volume provided a correct fit with the well data. We evaluated some examples of full-waveform inversion results on the same data set, which may lead to near-future improvements in the resolution of the depth-velocity model and the corresponding migrated image.