Shale Gas Technology: Lessons learnt in Poland
“Romania has resources and is willing to explore this potential,” said Valentina Ivan, Energy Policy Analyst, Candole Partners, in her introduction of a session dedicated to technology and best practices in unconventional drilling at the Romania Oil & Gas conference in Bucharest, Romania.
She remarked, “Private operators have already expressed interest to delve deeper into this, but so far we've only drilled one well.”
The focus in Romania, she said, has been on whether the proper regulation is in place as well as environmental impact studies, but social acceptance issues are polarized.
How to be more effective in the process of unconventionals exploration was the subject that Frank Thompson, Unconventional Resources Development Manager, Europe, Schlumberger, grappled with in his presentation, as part of the session.
He said that because of the effective E&P of unconventionals in places like the US or Argentina, interest in doing so in Europe remained. Of the areas to explore on the continent, Mr. Thompson admitted that most of them have note been explored.
What had occurred in North America was not, he said, just a matter of drilling a horizontal well and performing hydraulic fracturing to produce gas. “It took years,” he remarked. “Decades. It took a historical approach of drilling hundreds of wells, kind of like a shotgun to hit a target before we actually found the wells that we could produced.”
Regarding the history of emerging shale plays in the US, like the Barnett, he said literally several hundred wells have been drilled before it became commercial to find gas in place.
“Today in Europe, this is obviously not going to happen,” he admitted, adding that there were only 120 drilling rigs in all of Europe making it impossible to drill hundreds; population density in Europe is also too high.
“So, in the same area we'd very much like to do things a bit differently, use the technology that we have, the knowledge and expertise we can tap into,” offered Mr. Thompson. “We can do things like pre-drill monitoring, we can look at look at cultural data – population density, increase the chance of success for the first well that we drill, and in the same area we can drill a lot fewer wells, but would like the first well to be successful.
“Nothing kills a project like drilling unsuccessful wells,” he added, because after three strikes the project is over.
Mr. Thompson vaguely referred to the exploration activities in Poland, which he said could have benefitted from a “more focused approach.”
Understanding the rock was the first priority when looking for shale resources, according to him.
“Does it have gas in place? Oil in place? If yes, can we produce it?”
This involved looking at the organic material – figuring what kind of kerogen is inside the shale rocks which determines what kind of hydrocarbon can be produced. “Type 1 cooks off into oil straightaway at low temperatures; Type 2 kerogen – marine, amorphous cooks off into gas at higher temperatures. So we need to know things like level of maturity of the organic material in the rock,” he explained.
He explained that having a reservoir that actually produces required having 1) the hydrocarbon in place; 2) the formation must have a seal to capture the produced hydrocarbons; 3) thickness – 20-50 meters to produce commercially.
Mr. Thompson offered, “One approach that we use to be a bit smarter about where we want to drill, is to use what's called a petroleum systems approach, where we understand that the hydrocarbon was generated in the gas- or oil-rich shales in the conventional plays, it's leaked out and we're tapping it today.”
Shales, he said, needed to still have the hydrocarbon in place – a self-sourced rock.
Schlumberger, he explained, used a technological workflow to look at available data for an area to be drilled, for which a geology model can be constructed, followed by a petroleum systems basin model.
“The main reason is to find out, was the rock cooked long enough to generate hydrocarbon?”
These, he said, are called predictive models on unconventional plays that begin with using available information on the subsurface, looking at things like structural maps, cross sections, seismic that has been acquired in a given area, or data on any wells that have been drilled. “We use this to build a geological model.
“It's important to update this living model as more data becomes available,” he explained, “because this model is also used for developing the resource in place, if we find something that's worth developing.”
Then, the geological model is transferred into a petroleum systems model, which shows what happened to the formation from the time it was deposited up 'til today. This mandates information about the temperature, type of kerogen and its maturity, which led to using a modeling system to recreate what happened to the structure during the earth's geological life.
“We want to look at how it was buried,” said Mr. Thompson, “how it was uplifted, eroded, the faults that were developed, the system stress induced by tectonic movements until we come up to the picture of how this formation exists today. This will tell us, if the time and temperature was long enough during its history to actually produce the gas and oil that we're looking for inside the shales. And, if yes, where to look for it.”
It also involves building maps to figure out where the best chance of success lies for drilling an exploration well and finding hydrocarbons, he said, which could even involve population density.
Mr. Thompson remarked, “We won't drill in the middle of Bucharest, for example. We might like to, because there are hydrocarbons under the ground here, but culturally you can't do it.”
Schlumberger, he said, also looked at transport systems' natural barriers; there are places it is impossible to drill because of a river being in the way, or a motorway. “We combine these and highlight the places where we have the best chance of success in terms of oil and gas being in place, and where we can actually go and drill for them.”
Data drives decisions, he said, that will make difference in how one explores an area. Sometimes, he recalled, drillers do not know the data is there. “We've found in the last couple of years that there's a source of data that's been very little exploited: cuttings that we have from old exploration wells.”
He explained that many national and international exploration enterprises that preserve bags of cuttings, stored in warehouses around the world. “If we're lucky enough in the area we want to explore for shale, we can actually pull those cuttings out of the warehouse and analyze them and get some more information. It's been done a couple of times,” he remarked, adding that one of Schlumberger's groups is able to bring a portable petrochemical and geophysical lab to a wellsite to test cuttings, even those that have been stored 40-50 years.
“We analyze the elements that are in the cuttings, the mineralogy, total organic content and can pick out the source rock from the non source rock,” he said.
Mr. Thompson recalled that his company had done this for four wells in an area that needed to be explored, from the 1970s. “With our portable field equipment, in about 2 weeks we had analyzed the cuttings form those wells completely. We found that even in a fairly small area there is a big variation in the thickness of the potential payzone.”
This, he said, led to the construction of a small map to determine where to drill a first exploration well, updating the project model and “play chance-of-success” map, subsequently deciding to drill vertical or horizontal pilot wells.
He offered, “We didn't use a shotgun approach; we targeted the right area, went and drilled, and found hydrocarbons – a real case study.
“So before we go out and do massive campaigns of exploration wells, which basically won't happen, think about what we're doing beforehand – take some time for the pre drill studies to increase our chance of success, and think about it before you take action,” concluded Schlumberger's Frank Thompson.
Making the best choices regarding water management issues in unconventional gas development was the topic of a presentation by Anna Kanieweska, Business Development Lead Poland and KAMs Lead Europe, Golder Associates.
“We need to think about the availability of water,” she said, explaining that it was used for both shale drilling and hydraulic fracturing, and such water use comprised about 1% of water consumption in Poland.
This, she said, requires considering competing resources for water, like domestic usage, industrial, recreational or agricultural. Droughts also can be a concern.
Well stimulation, according to Ms. Kaniewska, can use up anywhere from 7,500 to 18,000 cubic meters of water, depending on the formation. Because the geology in Poland is challenging, she said a lot of water was necessary.
She offered, “Romania is really poor in terms of water resources, so it's an important consideration.”
Water management, she said, should be thought of as a lifecycle or a supply chain; it is necessary to assess the risks at each stage of it, considering sources of water, transporting of it, management, storage, treatment, reuse and disposal, as well as alternatives to all of those choices.
Regarding what kind of water should be used, she listed ground water, surface water, industrial water and the reuse of previously used water.
Ms. Kaniewska distinguished flow back water – that which re emerges from fracking a well – and produced water, the naturally occurring water in the geological formation, which often had things like leached metals or naturally occurring radioactive materials.
“Methods like filtration can be used,” she explained, “to remove suspended solids.” Also, biological treatments are available for removing organic compounds in produced water, she added.
For drillers, it is also necessary to plan for things like spillage, as well as to consider the traffic and safety concerns in communities. Of the locals in those areas she said, “Those people have lived there for centuries and the operators are only guests, so we need to consider their needs and address them adequately in all the decision-making processes.”
It was quite important, according to her, to reduce both freshwater usage and reduce the amount of waste water generated; Ms. Kaniewska spoke of different treatment options for the latter.
Finally, she reviewed several decision-making tools for assessing the options and risks to be able to make the best choices as part of a water management strategy.
-Drew Leifheit