Squeeze cementing is the process by which hydraulic pressure is used to force cement slurry through holes in the casing and into the annulus and/or the formation. Squeeze cement jobs are often used to carry out remedial operations during a workover on the well. The main applications of squeeze cementing are:
• To seal off gas or water producing zones, and thus maximise oil production
from the completion interval
• To repair casing failures by squeezing cement through leaking joints or corrosion hole
• To seal off lost circulation zones
• To carry out remedial work on a poor primary cement job (e.g. to fill up the annulus)
• To prevent vertical reservoir fluid migration into producing zones (block squeeze)
• To prevent fluids escaping from abandoned zones.
During squeeze cementing the pores in the rock rarely allow whole cement to enter the formation since a permeability of about 500 darcies would be required for this to happen.
There are two processes by which cement can be squeezed:
• High pressure squeeze – This technique requires that the formation be fractured.
which then allows the cement slurry to be pumped into the fractured zone.
• Low pressure squeeze – During this technique the fracture gradient of the formation is not exceeded. Cement slurry is placed against the formation, and when pressure is applied the fluid content (filtrate) of the cement is squeezed into the rock, while the solid cement material (filter cake) builds up on the face of the formation.
Institute of Petroleum Engineering, Heriot-Watt University