Tighter drilling on tighter margins


New coal seam gas field testing of Tight Radius Drilling (TRD) technology at an operation in the Bowen Basin is delivering successful results.

These tests, of the technology developed by CRCMining, are the first time that the radial drilling system has been deployed under the Petroleum and Gas legislation.

Originally developed for coal mine gas drainage, Tight Radius Drilling is an alternative to fracking.

The system uses high pressure water jets connected to the surface via flexible house, and is deployed from a conventionally drilled vertical well to create a series of lateral, horizontal boreholes in coal seams.

These boreholes then allow the trapped gases to be drained.

According to CRCMining, one of the key advantages of this water jet drilling system over hydraulic fracturing are the drilling rates, which in the Tight Radius Drilling systems can be higher than four meters per minute.

“Over a six hour drilling period, TRD has been demonstrated to drill over 350 metres within the coal seam,” CRCMining stated, “significantly increasing connectively to the gas reservoir at a very low cost.”

“It is a rapid, continuous, flexible and controlled drilling system, [and] trials have proven TRD provides greater costs savings than other surface to in-seam techniques as TRD is more effective in capturing fugitive carbon emissions with lower production risks.”

This technology can also be used for the commercial production of coal bed methane as well as for the seam drainage ahead of coal mining operations.

“TRD also enables low-cost, targeted de-gassing in difficult drain areas; as a step change for safety in coal seam gas extraction, TRD enables remote operation and eliminates rod handling during drilling.”

Trials began a few years ago at BHP’s South Walker Creek coal mine, located 40 kilometres west of Nebo in the Bowen Basin.

These trials have been aimed at validating comparative modelling between medium radius drill and TRD, with data demonstrating how tight radius drilling outperforms traditional drilling.

Five well trials have been carried out successfully, below cost, and gas production from the wells continues to increase, CRCMining said.

It allows for multiple laterals for redundancy and flexibility in difficult geology; multiple seam simulation; showed 300 metres plus of laterals with no ‘mud cake’ skin effects; and has an ability to connect to the reservoir.