Melissa A. Scott, Smith Energy Services a Division of Smith International, Inc.
One of the problems encountered in stimulating low pressure and/or low permeability sandstone reservoirs is recovery of the treatment fluid. Some wells have low bottomhole pressures and in many cases these pressures are so low as to give little or no aid in treatment load recovery. Reservoir permeability is determined by the relative number and size of pores as well as by the size and continuity of the pore intersections. Permeability is unique to a particular reservoir and cannot be altered by stimulation. Sandstone pores often contain water, creating capillary pressure which effectively prevents or restricts the passage of fluids. The interaction of aqueous based stimulation fluids and low pressure and/or low permeability reservoirs often results in less than desirable recovery of treatment fluids. A new surfactant technology has been developed to improve load recovery percentages.