ABSTRACT
Squeeze cementing is, by historical definition, the application of differential pressure across a cement slurry to accomplish the process of cement dehydration. The primary purpose of the dehydration is to create immobility of the cement slurry until some compressive strength can be developed. Current cementing technology and additives have improved the process sufficiently that the term "squeeze" may no longer be applicable. It is felt that "Remedial Cement Placement" may be more appropriate, and may more accurately define the process.
The success of a remedial cementing operation depends on a finite definition of the existing problem and the results expected from the operation. If the purpose of the squeeze is not definable, a squeeze job may not be necessary. Significant completion dollars are wasted annually on unnecessary squeezes, poorly designed squeeze slurries, and/or improper slurry placement. Many of the various applications of squeeze cementing may be classifiable as one purpose, i.e., repairing the primary cement sheath to isolate producing intervals and protect the casing string. Proper placement of a low-water loss cement slurry, at minimal surface pressure, into the casing-open hole annulus can satisfy most requirements of squeeze cementing. Initial breakdown pressures and pump-in rates prior to squeeze operations should be conducted at less than Bottom Hole Fracturing Pressure, (surface pressure [or ISDP] + hydrostatic pressure = bottom hole frac pressure). This will insure the placement of the slurry into the annulus, not into the formation. High pressure squeezes are not required, and are in fact, discouraged.
Placement of large volumes of cement slurries into the formation via created fractures, natural fractures, vugs, or zones with worm holes seldom satisfies any squeeze performance criteria; including improvement of GOR, WOR, or isolating a zone for stimulation (block squeeze). If the initial breakdown and pump-in test cannot be performed at sub-fracturing pressure, the cement sheath is competent and the squeeze operation is not required.
