Middle East Energy. INERT CENTRALIZER SYSTEMS FOR THE DRILLING INDUSTRY. Necessity of Invention. Metal manufactured centralizers appear capable of ensuring that the casing is correctly centered prior to the cementation.
Metal manufactured centralizers appear capable of ensuring that the casing is correctly centered prior to the cementation.
However, it is often the case that a significant number of the centralizers are rendered useless during the installation process.
This is because many of the bows will flatten against the casing when encountering a slight obstruction/protrusion from the formation wall, key seats, ledges or when the weight of the casing exceeds the tensile strength of the mild steel.
Either Way, the bow does not reform, unless constructed from expensive spring steel. Once some of the centralizer bows are deformed, there is nothing to stop the casing from resting against the wall of the hole during the cementation, resulting in a compromised cementation job.
The section of casing adjacent to the thinner or even non-existent parts of the cement sheath, will almost always be the first part of the casing to fail over time due to corrosion, particularly when that section is located within an aquifer containing high salinity water and/or gases.
A second major flaw of mild steel centralizers is the vulnerability of the centralizer itself to corrosion.
Whilst it is true that the function of a centralizers is usually to hold the casing central in the bore only until the annulus is cemented, mild steel centralizers can compromise an otherwise perfect cement job as they corrode over time.
Metallic centralizers are in contact with both the casing and the wall of the formation, even after the annulus has been cemented. As a result, groundwater is in contact with the outside edges of the steel centralizers and it will often completely corrode over time, leaving behind a channel or conduit through which the corrosive water and/or gases can travel and come into direct contact with the production casing.
In any case, the inevitable result of both situations is the eventual complete failure of the bore due to corrosion of the casing.
Corrosion issues aside, most drillers will admit to almost having nightmares about the thought of any metallic casing centralizer becoming jammed and breaking up in the hole during casing installation. This scenario is particularly worrying when non metallic casing/coatings are used (FBE, FRP, uPVC, etc).
Features and Benefits
Manufactured as segments from a corrosive resistant
Ultimate Inventory control – Two sizes fit all casing
sizes (2-3/8” to 7” – 155 Series)(7” to 36” – 380 Series).
Ideal for use on all types of Casing, Tubing, Screens,
Expandables, Chrome, CRA’s.
Pre-set centralizer bows and Annular Spacer Fins,
promoting cement flow and optimum stand-off.
No Stop collars required.
Will not damage Casing.
No Pins, Bolts or Welding.
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