Performance Test of Casing Centralizer
ZHENGZHOU, JUNE 30,2016-In order to have favourable and sucessful cementing effect,casing centralizer must be tested according to API 10D standard(the test standard is mainly applied on bow spring casing centralizer),bow spring casing centralizer which is basically designed for vertical wells where low starting forces and high restoring forces are required, is one of casing centralizer.High quality and passed casing centralizer is good in centralization of casing string and easy to running the casing in the wellbore.The high quality spring-steel bows which are heat treated to optimize standoff play an important role in providing excellent downhole durability and performance.
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From three forces like restoring force,starting force and running force,performance of bow spring casing centralizer can be confirmed.Generally speaking,The higher restoring force,The better perforce validated to API Specification 10D.
Restoring force is the force exerted by a casing centralizer against the casing to keep it away from the bore wall.At 67% stand-off ratio,the restoring force of casing centralizer is determined.According to our oilfield experience,stand-off of 75% to 90% is enough.
The running force represent the maximum force required to slide the inner pipe inside the outer pipe once the force reading has become steady.
Readings of force used from the time, the casing centralizer is inside the outer pipe until the inner pipe is completely in place being recorded and the maximum force reported as the running force after compensation.
The spring action of each bow is verified by 12 times compression testing.