Bass Strait: Long history, bright future

Lewis G. Weeks

How we turn the 'impossible' into 'easy oil'.

Article from ExxonMobil's employee magazine 'Connection'

Gippsland operations had their genesis in a historic meeting on March 18, 1960, between American  geologist Lewis Weeks and BHP Chief General Manager Sir Ian McLennan.

Lewis told Sir Ian that the place to go looking for oil was Bass Strait. This suggestion alarmed Sir Ian. “Lewis, have you ever seen Bass Strait? It’s some of the roughest water in the world.” He said there would be problems in drilling, and, if oil was found, great difficulty in producing it.

Lewis, who two years earlier had retired after a long career with Standard Oil of New Jersey (later ExxonMobil), said he had not seen Bass Strait, but there was no need to worry – it was purely an engineering problem.

This comment sums up the dynamics of the oil and gas industry the world over. The geoscientists find the resources and then the engineers devise the ways and means to produce them. This often involves extending the limits of current technology.

This is why there never was an era of easy oil – it’s only easy after the engineers have invented a way to develop it.

As Bass Strait was very much frontier territory for the offshore industry, its 40 years of production has been marked by continuous engineering excellence.

Derrick Barge installing living quarters on offshore platform

“In the early years there were challenges associated with the conditions in Bass Strait, particularly the strong currents and unpredictable weather all year round,” explained Operations Technical, Surface, Manager Geoff Humphreys.

For the first two decades the offshore platforms had to be abandoned during extreme weather events. As we came to better understand the environment hundreds of millions of dollars was spent on a pioneering project to strengthen the first generation platforms.

This platform strut project was based on the concept of “the 100-year wave”.

This is the largest wave which statistically will happen once in a hundred years.

When the platforms were built this was estimated at 17 metres. However, this was later upgraded to 23 metres. The resources and effort that ExxonMobil devoted to research by meteorologists and oceanographers looking at Bass Strait led to significant advances in weather-predicting for the area.

While Exxon had previously strengthened smaller platforms in the Gulf of Mexico, it had never  attempted this on such a large scale. The innovative platform strut project involved teams of  engineers in Esso Australia, Exxon Production Research Company in Houston and local design, fabrication and construction companies.

“This was an outstanding engineering achievement that required a range of specially designed concepts such as the struts themselves, hydraulic internal lifting tools and an acoustic positioning system,” said Geoff.

“A great deal of the work our engineers do – whether it’s major projects like the platform struts, or day-to-day corrosion prevention, or inspections – focuses on ensuring the safety and  environmental integrity of our facilities throughout their life.”

Construction of platform jacket at Barry Beach Marine Terminal

Geoff explained how engineering was very much a collaborative process. “Engineers work in  teams to overcome challenges or solve problems. Each one brings a different perspective to the project – different expertise and skill sets. This is why we are so good at what we do. In ExxonMobil we have about 14,000 scientists and engineers – about 1,000 of who have PhDs. This is a vast amount of expertise that we can draw on. And over the years Gippsland has been an active depositor as well as a drawer at this global bank of technological knowledge.”

As the Bass Strait fields started to mature many of the wells were producing increasing volumes of water along with the oil. The engineers, in collaboration with Vortoil, developed world first   hydrocyclone technology for the removal of residual oil from formation water after it came out of the primary separators. “This process, which uses a method of high centrifugal forces in a vortex, is used throughout the industry today,” said Geoff.

“But progress doesn’t just come from technological breakthroughs such as this. Often technology advances in small steps – innovations developed by engineers as well as plant operations people in their day-today work.

“This has certainly been the case with advances in water handling and spill prevention initiatives in Gippsland’s operations. It has also been the case with our corrosion prevention work as well as pipeline laying, equipment and machinery maintenance, process debottlenecking and process control, safety improvements – in fact just about every area of the operations onshore and offshore.”

The pace of technology advancing above ground was certainly mirrored below the surface.

“Bass Strait has always been at the cutting edge of drilling and well completion technology,” said Field Drilling Manager Harry Longwell. “In 1979-80 we drilled two world record longreach wells from the Mackerel platform. The first, with a total depth of over 5.2 kilometres, took 170 days to drill. The second, over 5.5 kilometres took 138 days. “We went back to Mackerel in the mid-’90s and drilled a 5 kilometre well in 54 days. We also pioneered geosteering technology using logging-while-drilling tools that improved the accuracy and effectiveness of our wells.

“In 2005 we were among the first to use ExxonMobil’s latest Fast Drill technology that represented a further  step change in drilling time and costs.”

Advances in geoscience technology have continued to open up new opportunities for Bass Strait. The most significant change has been the deployment of computing and communication capabilities enabling advances in geoscience and engineering reservoir modelling  applications.

“In the mid-80s we received the first desktop seismic workstations,” said Operations Technical, Subsurface, Manager Brad Bowman. “Although a far cry from what we use today, nevertheless they certainly changed the way we work.

“Geologic and reservoir models that took days to run and weeks to interpret are now being used between wells on our drilling programs, with the data of the previous well, being used to better position the next target location.”

But Brad said the greatest advance over our 40 years of production has been the growth in our knowledge. “You only have to consider the fact that when Bass Strait production began, 3D seismic surveys, routinely used today to map the subsurface, were not even available to us,” he said.  “As production from this basin progressed, and our technologies developed, so has our understanding of the subsurface environment. “It’s this knowledge, more than anything, that presents us with new opportunities to extend our field life and get greater value from the billions we have invested in infrastructure here.”