Complete Cementing Solutions Brochure

Testing Restoring Force Centralizers provide the restoring force necessary to keep casing centered in a wellbore. Restoring force is the force exerted by the Bow Spring of a Centralizer against the casing to keep casing away from well bore wall. The test is performed with the inner pipe and the outer pipe within 5 degrees of the horizontal. External force is applied to the outer pipe, which is then transferred to the centralizer. The load is then applied and load de fl ection readings are recorded three times. The process is repeated until each spring and each set of springs has been tested with the load being applied directly above them and then in between the two springs, as shown in figure A & B. When the minimum restoring force has been obtained and each spring has been tested, the final load deflection curve is prepared using the arithmetic means of the force reading at corresponding deflections. Restoring force is determined from this curve at 67% stand off ratio. Field experience shows that stand off values of 75-90% are adequate even in horizontal wells.

Figure A & B


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