Abstract
A gas well in the Gulf of Mexico was frac packed with 40/60 mesh gravel using a high temperature borate cross-linked HPG polymer fluid. The flow rate and wellhead pressure were monitored during cleanup. When no further cleanup of fracturing fluid was observed, a multirate test and pressure buildup were conducted on the well. These data were interpreted to give: reservoir permeability and pressure, skin factor, fracture half-length, and fracture conductivity. The multirate testing provided the non-Darcy flow coefficient. Based upon the flowing cross sectional area of the gravel filled perforations, the non-Darcy coefficient was assumed to dominate the completion pressure drop. This coefficient was analyzed to yield the permeability of the gravel in the packed perforations connected to the fracture. This initial test and analysis showed that the permeability was much less than laboratory measured values. This damage was attributed to residual polymer damage. The well was monitored for one year. During this time, the gravel permeability increased. A multirate test and pressure buildup test were performed one year after treatment, and analysis showed that all damage to the gravel permeability had disappeared. The calculations used in these analyses are presented.
