Scott Singleton, geophysical technology adviser at Independence Resources Management in Houston, wants to underscore that one word. He believes that if there’s a single ingredient to success in unconventional fields – and the one concept from which those in unconventionals have unfortunately moved away – it’s that geologists, geophysicists and engineers have to work together for the benefit of everyone.
“Although geology, geophysics and engineering are considered the ‘big three’ disciplines in the conventional oil and gas industry,” Singleton said, “in the unconventional industry this is not so, due to the dominant position of engineering in the factory drilling paradigm.”
He said that dominance is where the glitch, when it happens, happens.
“One of the problems with factory drilling is that it is blind to the subsurface and new wells are efficient only when many prior wells have been drilled,” he said.
To effectively correct that, while encompassing the disciplines, Singleton, who is the Society of Exploration Geophysicists’ second vice president, touts geomechanics modeling and simulation to increase efficiency in the field. It does this by modeling the effects of completions in various stacked reservoirs and then optimizes completion strategies once a landing zone is decided upon.
It takes some work getting there, but ultimately the work, which is relatively easy, is more cost-effective than relying on drilling alone.
“To build a valid geomechanical model requires a detailed and comprehensive geophysical workflow,” he said, “consisting of seismic petrophysics, rock physics modeling, full azimuth and wide bandwidth seismic data that is processed anisotropically, and a geophysical reservoir characterization that outputs rock strength and other petrophysical properties.”
This need for greater unconventional resource assessment, which a factory drilling paradigm cannot do on its own, has been exacerbated by the downturn in the oil and gas and what Singleton calls “everyone’s fight for survival.”
A Return to Integration Philosophy
“Things were going along fine” until about 2015, he said of collaboration. “The industry loved it,” he said, but after the downturn, “the sad fact is that a lot of the integrated teams that used to practice that philosophy pretty much got ripped to shreds and a lot of those people just tossed out … on the street.”
Those who were left weren’t as willing to share ideas and work, he said, which he believes was a mistake, for they turned their attentions inward.
“The integrated philosophy took a bunch of hits and we’re seeing the effects of that now in terms of the number of abstracts being submitted that concentrate on the technical disciplines and comfort of those who write them, and away from a collaborative effort. It’s almost a rare thing now that the people will reach out across the hall to the guy or group that represents a different discipline,” he said.
Additionally, many of these companies that had been committed to collaboration lost their integrated teams. Singleton said re-constituting them should be job one.
“In no uncertain terms, we need to communicate that we are dead serious about returning to our roots and emphasizing the integrated nature of the unconventional business,” he said.
Building a Mechanical Earth Model
Specifically, the geomechanical model consists of an array of properties loaded into a network of 3-D cells. These cells are created by determining the x, y and z dimensions that are appropriate for the size of the model one wishes to create and considering the spatial resolution of data available. Stratigraphic units are defined by interpreted seismic horizons and include stratigraphic rules for layer terminations above and below each horizon. Faults can be input into this model, as well.
Following the construction of an appropriate geocellular model, a mechanical Earth model is built by populating each cell with properties. A MEM consists of two main components: rock strength and stresses (which include pore pressure), which are created by first assembling the individual components as logs at well control.
“These are referred to as 1-D MEMs. Once enough 1-D MEMs have been defined so that geologic changes within the model area are adequately represented, these 1-D MEMs are interpolated into the entire volumetric area, thus creating a 3-D MEM,” explained Singleton.
After the 3-D MEM is created, engineering data is loaded, including completions and production data, formation microimager fracture counts, microseismic data, tracer data, etc. This data forms the basis for data analytics which can take a number of forms.
“It is far easier and cheaper to test these configurations,” said Singleton, “in a geomechanical model than doing so in the field, especially considering that completions are a substantial portion of the cost of a lateral well.”
The more those involved with future development talk to each other, he asserts, the more successful everyone will be.
Getting Serious about Integration
The other aspect to this, said Singleton, who is also the SEG co-chair for the Unconventional Resources Technology Conference, is what happens before anyone even gets to the field: It’s how the industry talks, writes and ultimately thinks about the pursuit of unconventionals.
“Practically speaking,” Singleton said of the work at URTeC, both at the convention in Denver this past July and since, “we have actually trashed several sessions that didn’t attract a lot of attendance, merged several more that by their very nature were encouraging un-integrated abstracts, and then inserted integrated language in our call for abstract descriptions.”
So serious was Singleton and those at URTeC that they added an element in the rating process for abstracts which included the level of integration.
“We’re saying, ‘Guys, if you want to have your abstract accepted, you better pay attention to the new ratings that include integration.’”
The Role of Geology and Geophysics
Overall, he wants to re-emphasize that there is a place at the table – a continued place – for the geologists and geophysicists.
“The big boys – ExxonMobil and Chevron – are going down the path of factory drilling. This means they have to do all the G and G work up front. The problem for us G and G guys is that with that factory paradigm, once they figure out all those things, hypothetically speaking, G and G is much less important,” said Singleton.
The fear is that some of those positions can be eliminated and engineers will take over, which they actually did early on in unconventional plays.
“We’re still suffering from that and we have to convince the industry that G and G still has a valuable place in the unconventional workflow, and that place is never going to go away, despite what some engineers might think,” he said.
The hope is that through the use of an integrated and collaborative visualization and analytics package – the geomechanics modeling and simulation – all disciplines involved in the production of unconventional hydrocarbons can finally unite and work together to achieve the vision of economically sustainable development.
“Geophysics has an important role to play in unconventional resource development,” he said, calling it the “glue” that pieces together discrete well data and provides stratigraphic information unavailable from anywhere else.
“Engineers are always going to be king,” he conceded, “but we just need to convince them we have a valuable part to play, even in the factory drilling paradigm.”