Casing Centralizer Selection and Installation
ZHENGZHOU, JUNE 28,2016-The profect centralization is very important for completing high quality cementing operation. The engineers from Puyang Zhongshi Group provide more than just casing centralizers, they provide service of selecting and installating casing centralizers. What they do is to minimize the compromise between getting casing to bottom and achieving good zonal isolation. Therefore they need closed communication between cementing operators and API 10D certified casing centralizers manufacturer who have rich drilling experience in oilfield before production.
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Before production,they need analyze the conditions as follows:
1.Actual downhole conditions like H2S corrosion level, well trajectory,mud density.
2.Casing size and weight,hole size,connection type.
3.Restoring force,running force and starting force analysis.
4.Test result of torque and drag by simulations.
5.Evaluate the stand-off during cementing job.
Next Step they choose the casing centralizer type.
1.Vertical section:standard bow spring centralizers are recommended.
2.Shallow dog leg: high concentration of side forces exiting,semi-rigid centralizers are recommended.
3.Bulid section:Higher restoring force existing,welded hinged casing centralizers are recommended.
4.Extended reach horizontal leg:to reduce drag, rigid centralizers are recommended.
After they select the right casing centralizer and then it is time to install the casing centralizer.There are four kinds of installation of casing centralizers(see the details as follows,this picture is from Weatherford Casing Centralizer)
Fig1:Over the stop collar:this is the best choice of installation,the features are to pull bow spring centralizers into the hole,increase starting and running force,save time and cost;but the defect is possible to break the bows.
Fig2:Between stop collars:Solid rigid centralizers are recommended to use this installation.It needs to pre-install to save time and cost.
Fig3:Over coupling:save the stop collars,reduce the stand-off at midspan,for increasing running force,we do not recommend the installation.
Fig4:Between couping and stop collar:the installation is only used in limited casing centralizer travel,using one stop collar can reduce the cost,not used in pipe racks.