A History of Frac-Pack Scale-Inhibitor Deployment

Abstract

In recent years, BP has moved into reservoirs in deep water subsea projects where sea water flooding is required for reserves recovery. The introduction of sulfate rich seawater into a reservoir producing a formation brine rich in barium ions significantly increases the potential for barium sulfate scale deposition. This type of scale is not acid soluble, unlike the carbonate based scales traditionally encountered in many regions. Alkaline based chelants, such as EDTA and DTPA, are only effective at removing small accumulations. Mechanical removal is generally considered to be the only effective removal option for significant sulfate scale deposits in the tubing but is not appropriate for removing scale from within the near well bore area or within a frac-pack or screen. Thus the recommended management strategy is one of prevention rather than remediation.

Preemptive Scale Management: Treating with Scale Inhibitor While Frac Packing a Well

“…For these reasons, preemptive scale management techniques that can be deployed during the completion operation are very attractive (Jordan et al, 2006). Previous studies by Fitzgerald and Cowie, 2008;Lungwitz et al 2007;Martins et al, 1992;and Vetter et al, 1988 have considered the technical and economic benefits of scale prevention treatment while simultaneously completing or stimulating a well. Benefits include better placement of the scale inhibitor through the near wellbore region and the fracture face, reduction in treatment cost and well downtime (particularly true in early stages of high production rate subsea wells), and minimum impact of early water breakthrough on operations (i.e.…”

Acid/Scale Inhibitor Stimulation Treatment for High-Temperature CHFP Subsea Wells: Fluid Qualification and Formation Damage Assessment

“…For these reasons, it is advantageous to develop an acid / scale inhibitor combination treatment that can be applied during the sand face completion process, thus removing post-perforating damage and preventing or delaying scaling in the near wellbore region. A few studies (Fitzgerald and Cowie, 2008;Lungwitz et al 2007;Martins et al, 1992;Vetter et. al., 1988) have considered the technical and economical benefits of simultaneously treating for scaling during the various stages of the stimulation operation, such as better placement of the scale inhibitor through the near wellbore region and the fracture face, reduction in treatment cost and well downtime (particularly true in early stages of high production rate subsea wells), and minimum impact of early water breakthrough on operations (i.e.…”

“…Despite the many advantages of placing the scale inhibitor along with the fracturing fluid, widespread application has been curtailed by incompatibilities with crosslinking agents and the difficulty to achieve significant gel strengths without compromising scale inhibitor performance. In response, some alternatives such as the use of encapsulated scale inhibitors and scale inhibitor-impregnated proppant have been proposed (Powell et al 1995;Fitzgerald and Cowie, 2008). The amount of scale inhibitor and scale protection that can be afforded with this approach is rather limited.…”

“…An acid stimulation treatment is usually conducted prior to the main frac operation in order to clean-up some of the perforation debris (including powdered metals from shaped charges) and residual fluid loss control (FLC) materials which can be a significant source of formation damage and plugging of screens and other wellbore jewelry. A few studies have also considered the technical and economical benefits of adding a scale inhibitor during the completion operation (Fitzgerald and Cowie, 2008;Lungwitz et al 2007;Martins et al, 1992;Vetter et. al., 1988).…”

“…al., 1988). The challenges associated with adding a scale inhibitor to the frac fluids are widely recognized, and some alternatives such as the use of encapsulated scale inhibitors and scale inhibitor-impregnated proppant have been proposed (Powell et al 1995;Fitzgerald and Cowie, 2008). The addition of scale inhibitor to the early stages of the frac operation has also been explored (Maschio et al, 2007), but the temperature ranges evaluated have been rather limited.…”