Earthquakes, hydrocarbons and the tobacco industry: lessons from the past
OKLAHOMA CITY – Most, if not all, Oklahomans are aware of the dramatic increase in the number of earthquakes we’ve experienced since the beginning of the last decade, and debate is raging about the connection between hydrocarbon exploration and production (E&P) and the occurrence of these earthquakes. On one hand, hydrocarbon E&P companies strenuously defend their practices of hydraulic fracturing (fracking) and deep well wastewater injection (DWWI) and dispute any connection to these earthquakes. If they were to be prohibited from using these techniques, less hydrocarbon would be produced in Oklahoma as well as many other areas of the US, negatively affecting both jobs and tax revenues; plus, it would increase our reliance on foreign sources of oil.
On the other hand, concerned residents and environmentalists are calling for a halt to these practices immediately, due to concerns about safety and groundwater contamination, which is also of great importance to Americans.
So who has the more compelling argument? Examining the parallel between this debate and the smoking vs. lung cancer debate of decades past may prove instructional.
The story of Big Tobacco’s misinformation campaign with respect to the health effects of smoking is well known. For years, the tobacco industry actively promoted weak, unscientific research and denied every bit of independent evidence for as long as they could. When faced with real evidence they could not deny, they resorted to using obfuscation and nullification, attempting to delay action as long as possible. One of the reasons this strategy worked for as long as it did, was that it is virtually impossible to connect any single case of lung cancer to any single pack of cigarettes. However, the scientific community has definitively proved that there is a causal connection between smoking and a myriad of diseases, including lung cancer.
The acceptance of this connection relies on three pillars of observation. The first pillar is a spatial connection: smokers contract lung cancer at higher rates than non-smokers. The second pillar provides a temporal connection: the longer you smoke the more likely you are to get lung cancer. The third pillar is the physical basis for connecting the first two: chemicals in cigarettes are known to cause cancer in animal experiments.
The tobacco industry’s years of denial essentially destroyed the credibility and reputations of virtually all tobacco-related companies. This is a lesson that the hydrocarbon exploration industry should study closely.
It is important to point out that, unlike tobacco, there can great benefits to exploring for oil and gas domestically. Energy independence is ultimately a positive for the American economy. However, the current tactics of hydrocarbon E&P companies actively engaged in fracking and DWWI seem to parallel that of big tobacco. Scientific research is routinely criticized and denials of a connection between fracking/DWWI and seismic activity (a.k.a., earthquakes) are commonplace. While we should, in general, support a strong domestic oil and gas resource, it is becoming increasingly difficult to defend an industry from people who are beginning to question them the same way we questioned Big Tobacco in the past.
Realistically, it is impossible to connect a single earthquake to a single hydrocarbon E&P or DWWI project. It is probably the latter that is a bigger concern, but the former is the catchphrase in the media and companies tend to dispose of wastewater on sites very close to the production locations, which can be the source of the general public’s confusion. The three questions that need to be answered are: 1) Is there is a geographical connection? 2) Is there a temporal connection? And finally: Is there a physical basis for connecting these practices with earthquakes?
Is there a geographical connection between hydrocarbon E&P and earthquakes?
Oklahoma has been a major hydrocarbon producing state for decades. However, there has been an explosion in E&P activity in the state in recent years. The Oklahoma Energy Resources Board (OERB) reports that oil production in Oklahoma has more than doubled since 2008. Nowhere is this more evident than in the Anadarko Basin, where the Woodford play has become one of the hottest targets in Oklahoma in the past decade. Taken from their corporate website, Figure 1 shows acreage and well locations for Chaparral Energy. This is a representative example since most other E&P companies would produce similar looking acreage and production patterns. Other significant players in this area include Newfield Exploration, XTO, Devon Energy, Chesapeake Energy, and Continental Resources, among others. All have essentially overlapping acreages in the Anadarko-Woodford play.
Figure 1 Exploration and Production map for Chaparral Energy. Figure obtained from their corporate website.
Earthquake location data for 2008 to 2013 are shown in Figure 2 for comparison. The data come directly from the USGS searchable database using a magnitude of ≥ 3.0 and a search radius 400 km centered on downtown Oklahoma City (35.5 N, 97.5 W). The locations of earthquakes and the locations of E&P wells both follow a southeast to northwest trend across central Oklahoma. Of the 265 earthquakes recorded in that time window, 243 occurred at a depth of less than 5 km (approximately 3 miles), the maximum depth for most E&P in Oklahoma. These data show both proximity and depth relationships between E&P and earthquakes.
Figure 2 Earthquakes M≥3.0 from 2008 to 2013. Data from USGS database using a 400 km radius centered over Oklahoma City.
Did the increase in earthquakes correspond to the timing of an increase in E&P?
The amount of production from the Anadarko Basin-Woodford has dramatically increased in the past decade. Figure 3 (from Wikepedia) shows gas production in Oklahoma from the Woodford since 2000. Very little production occurred prior to 2007. The advent of fracking in shale led to a rapid increase in production and a resulting increase waste water disposal.
Figure 3 Gas production since 2000 from the Woodford Shale. (from Wikipedia)
Figure 4 displays the annual earthquake frequency (using the same criteria as above) from 2000 to 2013. Again, only earthquakes greater than magnitude 3.0 are considered. From 2000 to 2007 there were a total of only 22 earthquakes. The frequency dramatically increased beginning in 2008, shortly after the increase in hydrocarbon production from the Anadarko Basin. From 2008 to 2013 there were 265 earthquakes in the same area. As of November 30, 2014 there have been a startling 542 earthquakes in the same area this year alone. It is clear that the timing of the increase in earthquake activity corresponds to the increase in E&P.
Figure 4 Annual frequency of earthquakes (M≥3.0). Data obtained from USGS database.
Is there a reason to believe that E&P activity can cause earthquakes?
Perhaps the most controversial argument is whether or not earthquakes can be caused by deep well injection of waste fluids. Some argue that the absence of earthquakes in other places where hydrocarbon exploration occurs demonstrates that there is no connection. However that is tantamount to arguing that “Granny smoked for years and did not get cancer, so smoking does not cause cancer”. The reality is that two things are required in order to generate earthquakes from E&P fluids: preexisting fractures with fluid injected directly into the fractures themselves or an increase in stress due to elevated fluid pressure nearby.
The ground beneath our feet in Oklahoma does contain numerous fractures. The two most famous are the north-south trending Nemeha Uplift fault zone running through central Oklahoma, the structure containing some of the earliest hydrocarbon traps exploited in this state, and the Meers fault in southwest Oklahoma, known to almost anyone who has looked at their seismometer while waiting for one of the best burgers in the state.
Any engineer understands that if a fracture is lubricated it is more likely to fail. In fact, anyone who has grabbed a can of WD-40 to loosen a bolt in their garage understands this. A nut that was stuck can be loosened with the same applied force after a quick spray. Fluids from DWWI can create a physical situation equivalent to spraying WD-40 on a rusty bolt. If fluid is not actually entering the fractures, then increased pressure from nearby fluid injection from DWWI is surely going to increase the stress load on the fractures. Thus, it is hard to argue that there is not a physical basis for connecting earthquakes to hydrocarbon exploration.
With a geographical connection, a temporal connection and a physical basis established, it is clear that there is a relationship between hydrocarbon E&P and earthquake events.
This leads to the next logical question: Will the hydrocarbon industry stand up and recognize that we must carefully plan where and how we produce hydrocarbons and dispose of wastewater, or will they continue to obfuscate and end up with a reputation equal to that of the tobacco lobby?
The reality is that hydrocarbon production is an important industry that creates high-paying jobs, revenue for landowners and provides a secure, independent, energy source for all Americans. However, we must do it in the right way, with minimal adverse effects on the environment. Until the hydrocarbon industry comes to the table with an honest assessment of their industry’s environmental footprint, they run the risk of becoming the “Big Tobacco” of the 21st century.
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