ZHENGZHOU,DEC 07,2016-Casing centralizer is a mechanical device around the casing to keep the casing from contacting the wellbore walls.The continuous 360 degree space around the casing is better to make the cement seal the casing to the hole wall.Casing centralizers play the importanct role in improving the cementing quality by preventing mud channeling and poor zonal isolation.Simply speaking casing centralizer is used for centralizing casing( also called running of casing ) and the prevention of differential sticking.
Casing centralizer is manufactured widely during oilfield serive. It is estimated that 8 million casing centralizers are manufactured and used every year all over the world wide.When casing centralizer manufacturers hear the number of centralizer,they would like to increase the demand for casing centralizers.However ,on the other hand,cementing operators may be interested to ask why we need so much casing centralizers.
In fact casing centralizer is also used extensively.Due to the poor cementing job,the wellbore problems happen and arise year by year. Therefore casing centralizer properties and placements directly or indirectly affect the quality of the cementing job.It is the important task for cementing operators and oilfield serice companies to choose the right type of casing centralizer and place the right amount at the optimum positions on the casing to achieve a good standoff profile.
There are two following casing centralizers in cementing operation.The first centralizer is bow spring casing centralizer which is traditional ,simple,low cost centralizer,as you know OD of the bow springs are slightly larger than the wellbore,so this kinds of bow spring centralizer is mainly used in vertical or slightly deviated wells.The second centralizer is rigid casing centralizer whose OD is smaller than the wellbore,it works well even in deviated wellbores. Rigid casing centralizers are slightly more expensive and can cause trouble downhole if the wellbore is not in excellent condition.