Slurry squeeze cementing

High-pressure squeeze cementing operations are utilized where the hydraulic pressure is used to make new channels in the rock formations (by fracturing the rock) and force the cement slurry into these channels. 

Low-pressure squeeze cementing operations are utilized where the existing permeability structure is sufficient to allow the cement slurry to efficiently move in formation without making new fracture surfaces with the hydraulic pressure. 

Another technique for carrying out a squeeze cementing operation is the Bradenhead technique. This technique can be used to squeeze a cement slurry... 

Calculate the expected movement of tubing under conditions as specified below. Initially both tubing and annulus are filled with a crude of 30°API. Thereafter, the crude in the tubing is replaced by a 15-lb/gal cement slurry to perform a squeeze cementing operation. While the squeeze cementing job is performed, pressures p, = 5,000 psi and p = 1,000 psi are applied at the surface on the tubing and annulus respectively. 

Thick slurries will not fill a narrow channel well. Therefore squeeze cement slurries should be rather thin. Dispersants should be added for this reason. High compressive strength is not necessary for these types of slurries. 

Incomplete displacement of fluid from the annular space can result in gaps in the cement sheath through which fluids from different formations can intermingle. In this situation, a "squeeze cementing" treatment is required to plug these gaps. Portland cement or rapidly setting sodium silicate slurries can be used in this operation. 

Acids are sometimes used ahead of fracturing fluids to dissolve mineral fine particles and allow more rapid injection of the fracturing fluid. When used as the initial stage of a squeeze cementing treatment, the acid-promoted mineral and drilling mud particle dissolution can result in increased entry of the cement slurry into the desired portions of the formation. 

Two other types of operations involve cement slurries. They are used to plug back a well from a deeper to a shallower depth for a number of reasons abandonment, whip stocking, lost circulation, or shutting olf water. Squeeze cementing consists of forcing a column of cement slurry... 

A spearhead or breakdown fluid followed by the cement slurry is circulated downhole with the packer by-pass open. This is done to avoid the squeezing of damaging fluids ahead of the slurry. A small amount of back pressure must be applied on the annulus to prevent the slurry fall caused by U tubing. If no tail pipe has been run, the packer by-pass must be closed 2 or 3 bbl before the slurry reaches the packer. If the cement is to be spotted in front of the perforations, with the packer unset, circulation is stopped as soon as the cement covers the desired zone, the tail pipe pulled out of the cement slurry and the packer set at the desired depth. The depth at which the packer is set must be carefully decided. 

Squeeze pressure is applied at the surface. If high-pressure squeezing is practiced, the formation is broken down and the cement slurry pumped into the fractures before the hesitation technique is applied. If low-pressure squeezing is desired, hesitation is started as soon as the packer is set. 

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