02 September 2013, News Wires – Exploration and production, E&P, companies with onshore U.S. operations need to better understand shale oil formations and to modify certain environmental health and safety, EHS, practices, and these goals are driving technology development among oilfield service companies, according to several members of the service company community.
“We’re just in the infancy of our understanding” of shale oil plays, said Tim Ruble, a senior geochemist with Weatherford Laboratories in Houston. “Shale oil represents a much more complex system” than a shale gas formation, he noted.
“Gas is a very simple mixture of compounds – methane, ethane, propane, butane,” explained Ruble. “Oil is a very complex mixture of organic compounds – straight-chain hydrocarbons, aromatics, large asphaltenes – very complex mixtures. Understanding the physical properties of oil is much more complex.”
Deciphering the Shale Oil Code
Weatherford is developing technologies to generate three-dimensional, nano-scale models documenting exactly where the crude oil is present in a shale formation and is helping operating companies decipher the chemical composition and physical characteristics of the oil, Ruble said. The goal is to more clearly illustrate where oil resides, how oil moves within the rock and to provide data about the oil’s maturity and API gravity – factors that can help operators to map out the optimal sweet spot for drilling.
“You want to be able to predict where that oil is and you want to be able to recover that oil,” said Ruble. “To do so you need to understand the system from a chemical perspective, and you have to understand the nature of organic porosity in the system.”
Crude oil comprises a more complex array of compounds than natural gas, but some of the lessons the industry has learned to crack the shale gas code should – to a degree – contribute to a better understanding of shale oil plays, Ruble said. He cited as an example the great strides the industry has made in unlocking the mysteries of organic porosity of shale gas plays. (The term “organic porosity” refers to the “holes” within the organic material that produce hydrocarbons in a rock formation.) Some of this knowledge may be transferable to shale oil plays, Ruble said.
“We know it’s important with shale gas and we believe it’s important with shale oil systems,” he said. However, he cautioned that it is too soon to tell whether any transferability would be ubiquitous across all shale oil systems or whether different types of shale oil systems would need entirely new approaches.
Concentrating on the minutiae of shale oil systems may seem an esoteric research endeavour to some, but Ruble emphasizes the process supports an eminently practical outcome: helping operators to more quickly locate the most productive wellsites.
Weatherford is using new predictive tools like the Source Rock Analyzer (SRA) that incorporate early parameters for evaluating shale oil systems in order to give operators a competitive advantage to evaluate prospect areas and make proper decisions where to drill, he explained.
“It’s important to know, for example, if you have high oil saturation in the rock,” Ruble said. “I want to know that very early on. If I can find that out an hour or so after I’m drilling that I have high oil saturation within that zone, that could be a pretty good parameter for making a decision.”
Getting More Data Faster – and Closer to the Wellsite
Part of improving the understanding of an oil shale reservoir involves maintaining the integrity of core samples. During traditional coring operations, fluids and gases can escape from the core sample. Losing such constituents diminishes the robustness of the information the sample would otherwise provide. Houston-based Corpro, a unit of ALS Oil & Gas, contends that it can provide operators core samples that accurately and quickly present the makeup of the target zone thousands of feet beneath the earth’s surface.
“We’re helping the operators to truly understand what the in situ numbers are,” said Jeff Sinclair, QuickCapture business development manager with Corpro.
The company maintains that its specialised QuickCapture tool, a core barrel designed to capture 100 percent of all in situ gases and fluids inside the core sample, provides operators with a clear snapshot of the mixture at the wellsite. The tool works on a wireline coring system called QuickCore that cuts a full-diameter core and, once completed, is then recovered via wireline.
By encapsulating a core sample from the reservoir inside a pressurised, sealed container that is sent down the wireline, the company contends that it can gauge the actual composition of the reservoir and provide a specimen for detailed lab analysis whose richness is unrivalled with conventional core sampling practices.
The emerging technology takes the guesswork out of reservoir characterisation and directs operators toward a clearer strategy for fracking and optimising production, said Sinclair.
An executive with ALS’ service logging subsidiary, Empirica, told Rigzone that advances in the application of established technologies are also helping operators to obtain richer data in a more timely fashion.
“We’re bringing technology from the laboratory to out in the field, more economically,” said Jordan Dawson, general manager of U.S. land with Empirica.
X-ray diffraction/x-ray fluorescence, XRD/XRF, which is used to analyze drill cuttings to pinpoint target zones, is a good case in point, he said. Using XRD/XRF once required operators to send cuttings offsite for geologic interpretation – a process that could take months, Dawson noted. Now, a mobile XRD/XRF lab can provide results in real-time and interpretation by an in-house geologist, he explained.
Nuclear magnetic resonance, NMR, which is deployed as a wireline tool to test for permeability and porosity in reservoirs, is another example of an established technology that is being used in a broader array of applications, added Dawson.
Also, “the next-generation mass spectrometry” is increasingly being used in tight sand plays, he said. “You can identify pay zones that are actually there, that 3D seismic may have missed.”
Ultimately, the trend toward finding ways to deploy existing technologies at the wellsite enables the operating company to do more with more, said Dawson.
“You’re actually giving them more information about their reservoir,” he said. “If they understand more, they produce more. If they produce more, they can have more rigs.”
Transforming Frac Water Management and Safety
Service companies are using novel approaches to characterise shale oil systems, but they are also devoting considerable resources to limit how much water is used in well stimulation, according to Kenny Jordan, executive director of the Houston-based Association of Energy Service Companies.
“One of the largest issues I believe will relate to water and its use and disposal,” Jordan said.
Emerging hydraulic fracturing technologies and processes are curbing how much water is needed to frac a well and to recycle the water that is used, Jordan explained. Directing this greater focus on water are state and federal governments, which are urging the oil and gas industry to recycle frac water and return it to the environment or “clean” it to the point where it can be reused without re-injecting it in a disposal well, he added.
Notwithstanding the push from regulators to tighten water use in well stimulation, the emerging trend also stems from the fact that the United States is the source of more of the oil and gas moving through the country’s value chain, said Jordan.
“As production increases throughout the U.S. on our way to less dependence on foreign resources, the recycling of water and less use of water resources will continue to benefit the entire environment,” he said.
Another EHS issue that is driving innovation among service companies is the ongoing desire to make handling tubulars and related tasks on well servicing rigs less “hands-on,” Jordan continued.
“The largest cause of accidents in the well servicing industry is ‘struck by and caught between’ accidents,” he said. “If ways can be developed where rig floor/derrick personnel have less direct contact with the tubulars, then companies will benefit from a safety perspective. There have been some advancements in this area in the last few years. I think you will see more companies at least exploring this approach in the future.”
In addition to improving safety for well servicing rig personnel, service companies are actively working to address the issue of driver fatalities, Jordan noted.
“Driving-related fatalities are the leading cause of death in our industry,” he explained. “Companies are utilising monitoring of vehicles, equipment through remote facilities to assist them with better utilizing their assets, and also to monitor driving habits.”
“I believe we will see additional developments in this area in the coming months,” concluded Jordan.