In 2005 the project, which took place in the Pohokura gas field, off New Zealand’s North Island, achieved the longest shore approach crossing using horizontal directional drill (HDD) in the world.
The Shell engineers were very progressive and open to sound engineering, so by delivering a level of project engineering far above what Lucas had been used to they were able to take away much of the risk of the unknown.
Reflecting on the project, AJ Lucas’ Stephen Lonergan said “We adopted many of the offshore approaches to planning by conducting a number of drill well on paper sessions.
“These were normal for Shell but new to us at the level of detail required.
The experience has stood us in good stead ever since and has become a foundation of our project planning.
Many of the spreadsheets and procedures we still use today.”
Some of the main challenges with the project involved drilling fluid control and fluid technology, due to the dispersive nature of the formation, combined with the fact that the pipe had to be forward thrust 1,750 m with no cutting assembly.
Hole stability was also a key issue and largely dependent on fluid technology.
In the HDD industry old fashioned bentonite is a mainstay, but is fast becoming unsuitable as the bores become longer and more complex, certainly from an environmental perspective.
Progress after the project
Following the Pohokura Project, AJ Lucas has pushed the lengths and diameters in plastic clay formations, while gaining a considerable confidence and knowledge to pursue forward thrusting as an installation technique, with several projects undertaken since then where a traditional pipe side sting was not possible to construct.
HDD projects are now an intimate study in risk management, and since 2005 AJ Lucas has continued to look more carefully at risk management.
“Managing risk through engineering and client involvement has been an increasing focus for Lucas.
“We have not pursued the mantra of the bigger the rig the bigger the job, but rather the bigger the rig the bigger the problem it can cause.”
During the last ten years the innovative tradition has continued, with some of the project highlights that have given rise to an increased capacity including:
- 2004: Lucas forward reaming a series of 250 Mpa granite bores in Hong Kong, which had a drilling radius so tight the drill pipe could not be rotated without risk of breakage, with the exit point being a tunnel inside a mountain;
- 2005: Lucas established the longest forward reamed shore approach crossings at 1,850 m for Shell in New Zealand;
- 2006: Lucas successfully forward reamed with downhole motors a 44 inch ( 1,117 mm) hole 1,350 m long in Newcastle;
- 2007: Lucas once again set a length record by drilling dual bores in the Blue Mountains, west of Sydney, to a length of 2,500 m each, to a tunnel nearly 100 m underground. Again, no intersect technology was used;
- 2008: A series of bores were completed for the Queensland government, three of which were under the notorious Brisbane River, which is known for its treacherous gravel layers that have caused serious issues with other projects;
- 2010: Lucas completed what was contractually the largest HDD project ever attempted, in the work for Chevron at Barrow Island, Western Australia. A series of nine shore approaches in highly porous formation was tricky
enough, but the environmental and logistics requirements of working remotely in a class A nature reserve provided many levels of project complexity; and, - 2014: Lucas continues to progress well with the detailed design and engineering of two 5,100 m long bore holes that are planned to be drilled and reamed from a single side.
The future for HDD
With some 25-plus drilling rigs with a capacity over 250 t in Australia now, Mr Lonergan believes the future of the HDD industry will revolve heavily around establishing real credentials, backed by sound engineering principles.
“The HDD industry uses many of the same tools, equipment and technology found in the petroleum drilling industry, they are drilling 15 km wells nearly all of which is close to horizontal,” Mr Lonergan said.
“While the cost structure of those wells is different to the drivers we have, it does show that the HDD industry has a long way to develop yet – as long as there is a professional adoption of professional standards.”