Seismic attribute analyses to optimize the placement of tight gas horizontal wells

The Xiashihezi Formation in the Ordos Basin, China is a quartz-sandstone reservoir having low porosity, low permeability, and low pressure. Its quality is controlled primarily by deposition facies and secondarily by diagenesis. The principal targets of horizontal drilling, completion, and production are the thick massive sands and the vertically stacked sand beds. In this study, we acquired 266 km² of three-dimensional (3-D) seismic data, 20 vertical and 25 horizontal well data to show the potential of seismic attribute analyses in locating geological and engineering sweet spots for the placement of horizontal wells. The joint analyses of amplitude, texture, curvature and frequency attributes demonstrate that the geology, geophysics and the horizontal drilling properties of the reservoir are linked. The study results have improved the placement of horizontal wells in tight gas reservoirs of the Sulige gas field.