Queensland Gas Company (QGC) has recently announced that it will drill 161 new coal seam gas (CSG) wells in the Surat Basin in Queensland, a move that will enable further supply to both domestic customers and natural gas exports.

There are a number of challenges that such projects present, such as remote locations, the number of wells being drilled, and the casing material. Choosing the most appropriate products can help mitigate some of these problems. Products such as centralizers play a small but important part in ensuring the integrity of a CSG well for its full lifecycle, and reducing project costs.

Low-cost and flexible design

Located in the Great Artesian Basin in eastern Australia, the Surat Basin covers an area of 270,000km2 across New South Wales and Queensland. It’s a relatively remote location, and the high number of wells is one of the challenges for drilling contractors.

Jason Linaker, Managing Director at kwik-ZIP, said, “Working at remote sites such as the Surat Basin, there are a few considerations drilling contractors should take into account, including the use of trusted products with low inventory and transport costs.

“Products sourced from overseas can cause costs to skyrocket due to transportation costs, not to mention the time it takes to ship to Australia can slow down a project if more stock needs to be ordered part way through a project.”

Sourcing products that can be used across the whole site is also something to consider.

“When there are a high number of wells that need to be drilled, time and money can be saved if the same drilling products and associated equipment are used across the site,” Mr Linaker said.

“This removes any confusion for the workers, and cuts down on training time for each product. It also provides continuity across the project, with one point of contact if any technical advice is needed.

“kwik-ZIP centralizers for CSG wells have been designed by drillers for drillers, ensuring the design takes into account these common problems found across remote CSG sites in Australia.

“The design and packaging of kwik-ZIP centralizers is segmented, making them easy to transport across long distances at a low cost. As kwik-ZIP centralizers are held in a number of warehouses across Australia they are also quick to deliver so there’s no long periods of downtime if more stock needs to be delivered to a site.”

kwik-ZIP centralizers are also designed to be flexible to allow for different casing/borehole diameters and combinations by altering the number of segments used to make the centralizer.

“The flexible nature of this design means that only one product is required across the site rather than multiple, which can drive up costs,” Mr Linaker said.

“Furthermore, on-site personnel only need to be trained in the one centralizer system, instead of different centralizer designs and brands for each well of a differing size.”

An alternative to metallic centralizers

Fiberglass and glass reinforced plastic (GRP) well casings are commonly used in CSG wells.

However, these casings are not as strong as standard steel casings, so if a metallic centralizer is used, there is a risk of damaging the casing surface.

For example, if metallic centralizers were attached to a fibreglass casing, any movement of the two components relative to each other could cause damage to the casing.

Stop collars that are used with conventional steel centralizers also present a problem for such casing materials as the bolts that fix the stop collars to the casing can crack the fibreglass or GRP.

kwik-ZIP products overcome these hurdles and are routinely used for well completions on CSG well casing.

Another benefit of non-metallic spacers is that they are corrosive free, so in areas where corrosive groundwater is present they won’t be affected.

“kwik-ZIP centralizer systems are manufactured from a quality alternative to metallic spacers and have integrated rubber pads which prevent movement on the CSG casing, eliminating the need for stop collars and preventing damage from occurring,” Mr Linaker said.

“This also prevents them from corroding, ensuring contractors have met the requirements to ensure well integrity and long bore life.”

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