When it comes to the long-term success of a drilling project, using a centraliser made from the right material can aid a well’s structural integrity, improve the performance and longevity of a gravel packed screen assembly, and reduce the effect of corrosion on the casing.
However, the varied nature of centraliser applications and job sites, whether it be for oil and gas, or waterwell drilling, means that it can be difficult to find a centraliser that fits each drilling project’s individual needs.
Here, Jason Linaker, Managing Director at kwik-ZIP, discusses four benefits of using centralisers for drilling projects and what you should look for when choosing a centraliser system.
Keeping pipes centralised
The primary function of centralisers is to keep the well casing and screen assembly centred in the borehole.
Mr Linaker said that correct centralisation of the casing and screen assembly prior to grouting and gravel packing ensures an even layer of grout is installed around the diameter of the casing, and provides for correct placement of gravel pack around the screen
“Maintaining an even grout cover during construction is important in achieving casing integrity. This not only increases the life cycle of the casing, but also seals it properly so that the potential for fluids to be released and migrate is minimised, preventing costly and damaging contamination of the environment, depressurisation of the well, and corrosion of the casing.
“Equally important, is correct centralisation of the screen assembly to ensure that the gravel pack is even and without voids. This will minimise the potential for the gravel pack to slump during pumping or to produce sand due to insufficient thickness of the gravel filter pack.”
Flexible design for a variety of clearances
Choosing a centraliser system that is flexible is another factor that drillers should consider.
“It is not uncommon for a project to require wells of different diameters to be drilled. For such projects, a centraliser system that can be adjusted to suit a wide range of diameters will save time and money as the same products and associated equipment are used across the site,” Mr Linaker said.
“Furthermore, on-site personnel only need to be trained in the one centraliser system, instead of different centraliser designs and brands for each well of a differing size.”
Preventing damage with inert centralisers
Fiberglass and glass reinforced plastic (GRP) are commonly used for casings but they are not as strong as standard steel casings. If a metallic centraliser is used, any movement of the two components relative to each other could cause damage to the casing.
Mr Linaker said that kwik-ZIP systems provide a solution to the problems presented by metallic centralisers as they are made from a high grade thermoplastic called ACETAL POM, which is strong and corrosive-free.
“kwik-ZIP centraliser systems are manufactured from a quality alternative to metallic centralisers, and have integrated rubber pads which prevent movement on casings, preventing damage from occurring,” Mr Linaker said.
kwik-ZIP systems are the only centralisers developed by drillers right here in Australia, so they were made for drilling applications that face the challenges of the harsh Australian environment, including areas with corrosive water and soils.
“In environments where corrosive soils or water are present, contractors should consider centralisers made from inert materials as the chance of corrosion damage is high, especially if the casing is made from steel. Corrosion is a problem as it reduces the life of the casing and places its integrity at risk,” Mr Linaker said.
The kwik-ZIP range, being completely made from thermoplastic, has no metal parts. This stops the product from being susceptible to corrosion, and ensures long-lasting, successful results across all drilling projects.
“While centralisers are a small component of a drilling project they can make a big difference to the long-term success of a well,” Mr Linaker said.