Natural gas is one of the biggest energy sources powering the Earth. But years of mining for natural gas have depleted reservoirs across the world.
Together, the United States and the People’s Republic of China increased natural gas consumption by 10% and 18% respectively in 2018, accounting for two thirds of the world’s increased consumption of natural gas. China’s adoption of the coal-to-gas substitution policy and the US’ growing power industry were the primary causes of increased gas consumption.
Now, with natural gas resources taking longer to mine and recycle, scientists and companies are in a race against time to identify new areas where natural gas is deposited. Two places where they’ve found an abundance of natural gas deposits are the Earth’s deserts and the ice-clad arctic regions.
While deserts have, for long, been the traditional mining areas for natural gas, research shows that a significant portion of the remaining 7,124 trillion cubic feet of natural gas is still available in the deserts. Other large deposits have been found in the glacial landscape of the arctic.
But why is this the case? Why is natural gas found in places like deserts and the arctic region?
The Role of Decomposition and Tectonic Plates in Natural Gas Formation
Before we address why natural gas is found in large quantities in deserts and the arctic, let’s look at how the natural gas formation process works. After all, how the gas is formed and where it is formed determines where it is finally located.
Normally, when an animal dies, the oxygen in the air enters the body and starts the decomposition process within three to four minutes of the animal’s death. Microorganisms start to break down the body of the animal, resulting in the release of enzymes and chemicals. Within a span of one year, the body will be stripped down to the bones, and any gases and minerals in the body will be absorbed by the Earth.
But, if the animal’s body were to be rapidly buried deep inside the Earth right after death, it wouldn’t have access to the oxygen it needs to decompose. As time goes on and the body is buried deeper and deeper under thousands of metric tons of soil, extreme pressure (plus a lack of oxygen) starts the thermal breakdown of the animal’s body. The by-product of this break-down is hydrocarbon – of which fossil fuels are an important part.
Just like any other fossil fuel, natural gas is formed when dead animal matter decomposes and is exposed to intense pressure from the earth. It can take anywhere up to 550 million years or more for natural gas to be formed.
Gas is the lightest of all the fossil fuels produced. But the intense pressure of the earth and the nature of the rocks in the soil prevent it from escaping into the atmosphere. Instead, natural gas is stored inside these rocks and can be obtained by drilling into them.
So let’s assume that an animal died over 600 million years ago. Its body was buried inside the earth in a particular place – let’s call it Place A – that’s at one end of the Earth. Now, as the natural gas is forming, something else is happening inside the Earth. The ever-evolving planet has tectonic plates (which are massive slabs of natural rock that make up the Earth’s surface or lithosphere), which are constantly in motion.
Tectonic plates typically move anywhere between 2 and 11 centimeters each year. Over the course of these 600 million years, the tectonic plate that contains Place A (and the natural gas) moves from one corner of the planet to the opposite corner. When the time comes to drill the natural gas out, natural gas is no longer in the area where the animal died 600 million years ago. Instead, it’s at the opposite end of the world, because the tectonic plate housing Place A has moved thousands of miles away.
That’s why you may find that the natural gas from the fossil of a dinosaur that died in Australia is now located somewhere in the Middle East. In fact, it is this movement of the tectonic plates that scientists believe have led to the creation of natural gas deposits even in the Arctic.
Now, let’s take a detailed look at this process.
How Natural Gas Reservoirs are Formed in the Deserts
Decomposition and plate tectonics aside, the formation of natural gas reservoirs in the world’s deserts are also impacted by the presence of very specific soil conditions. For one thing, the soil needs to be capable of creating conditions to attract and hold the right type of organic matter, which forms the base for fossil fuels. Second, the soil in deserts needs to possess certain types of rocks, which are capable of absorbing and storing fossil fuels for millions of years.
For a long while, we’ve known that the ocean (or any large water body) is instrumental to the creation of natural gas resources. Animal and plant matter sinks to the bottom of the oxygen-free anoxic waters of the stratified oceans (oceans, where only some layers have oxygen content and others don’t). Here, they are covered by sediment already in the ocean and sediment falling into the ocean from surrounding landmasses.
According to Alistair Fraser, a geoscientist at the Imperial College London, the temperature at the bottom of the ocean (where the organic matter lays buried) increases by 54 degrees Fahrenheit (30 degrees Centigrade) every time there is a 0.6 miles increase in the size of the sediment layer above the fossil. So this means that as time passes and the sediment layer grows in size, the temperature inside the ocean floor rises tremendously, creating the heat and pressure needed for the thermal break-down of the fossil and forming natural gas in the process.
But how does this have any connection to the world’s deserts? After all, deserts are dry, predominantly water-less, and don’t support any of the conditions that are required for the formation of natural gas.
But that’s where we are wrong. In reality, deserts – in particular those found in the Middle East (the largest reservoir for natural gas in the world) – were once entirely covered by an ancient sea.
The Tethys Sea is a now-extinct sea that once covered a large portion of the prehistoric Earth, starting from the time of the Paleozoic Era. In fact, there wasn’t just one Tethys Sea, but multiple Tethys seas.
While there are still debates about this, some scientists believe that the very first Tethys Sea was supposedly the Proto Tethys Sea. It is believed to have been formed at a time before the break-up of the Earth’s first supercontinent Pangea – a time when all the continents were fused as one.
But for official purposes, the Paleo Tethys Sea is considered to be the first Tethys Sea, and it was formed after the break-up of Pangea. It existed between the supercontinent of Gondwana (which consisted of regions known today as Africa, South America, India, Antarctica, Australia, and regions south of the Alpine-Himalayan range) and Laurasia (the amalgamation of the two minor supercontinents of Laurentia – which makes up present-day North America and today’s Eurasia).
The second Tethys Sea (formed during the Triassic period of the Mesozoic Era) is called the Neo Tethys Sea. It has led to the creation of a coastline that covered what is today known as the Mediterranean region.
Extensive tectonic plate activity during the millions of years that followed the creation of the Neo Tethys Sea led to the end of the ancient water body of Tethys. However, even today, we can find the remnants of the Paleo Tethys and the Neo Tethys inside the soil that forms the mountain ranges of Turkey, South Caucasus, Afghanistan, North Africa, the Middle East, Northern Iran, Tibet, Indochina, and China. Each of these places was formed by the collisions and rearrangement of tectonic plates. Additionally, it is these regions that we drill today for oil, natural gas, and petroleum.
So as the tectonic plates began moving, colliding and fusing, large swathes of the sedimentary soil from the Paleo and Neo Tethys Seas came together, creating extremely large pools of broken-down fossil matter in today’s Middle East and North Africa regions. You can see the same process mimicked in the regions we know today as Latin America. Over a period of a few million more years, this fossil matter became natural gas.
Now we know how the dry and arid Middle East (and some of the other desert regions around the world) developed the sedimentary conditions needed for the creation of natural gas. But it still doesn’t explain how the gas stayed in place for millions of years.
As we know, natural gas is very light, and methane is the lightest of all the natural gases. Without the presence of something that could hold it, natural gas from the ocean bed could have dissolved in the ocean millennia ago.
This is where sandstone comes into the picture.
Sandstone is a sedimentary rock – a rock formed in cold temperatures, typically under the sea/ocean bed. It’s made up of a combination of sand and minerals found on the surface of the Earth. Since sandstone is formed when layers of sedimentary material fall on top of each other, you can see multiple layers/strata on the rock – sometimes, each layer is a different color and texture, depending on its mineral composition.
The sand that makes up the sandstone is of medium-grained quality, that is, measuring between 1/16th and 2 millimeters. Compared to other types of soil, sand particles have a higher porosity. This means they have more space to hold and store hydrocarbons in them, ensuring they don’t evaporate into the atmosphere or dissolve into the ocean. As the natural gas forms, it gets trapped in the pores of the sandstone, getting lodged there until it is drilled out.
Sandstone typically has a porosity between 5 and 40 percent. Depending on its porosity and permeability (ability to let liquid/gas flow through), the gas inside the sandstone will either come up to the surface (where it will be prevented from exiting the surface by an impervious soil -to tap this, conventional extraction methods are used), or, if the sandstone has low permeability, the gas will continue to stay within the tight stone (it can be extracted only by breaking down the sandstone reservoir using unconventional extraction methods) until deliberately extracted.
In desert regions, like the Middle East, you get a combination of both ‘highly porous & highly permeable’ and ‘highly porous but with low permeability’ sandstone. This sandstone – which has been in creation since the time of the Tethys Sea – holds the natural gas that the desert regions boast of.
How the Arctic Got its Natural Gas Reservoirs
The Arctic Ocean and the surrounding glacial areas are expected to have over 30% of the Earth’s conventional natural gas resources (gas that can be extracted using conventional means). According to studies conducted by the U.S. Geological Survey, 1,670 trillion cubic feet of natural gas and 44 billion barrels of natural gas liquids are believed to be located in 25 areas North of the Arctic Circle, and they have a very high potential of being recoverable through conventional extraction methods. The area adjacent to the Alaskan continental shelf is believed to hold 72 billion barrels of natural gas, and the Alaskan North Slope (closer to the Arctic) is expected to have 80 trillion cubic feet of natural gas locked-up in Arctic rocks.
But how did this gas get here?
A little earlier in this article, we discussed how plate tectonics affect the placement of natural gas reservoirs. This is true of the Arctic too.
Unlike its southern cousin, the Antarctic, the Arctic region comprises of both water mass and landmass. Essentially, the Arctic ocean is a large water body that’s surrounded by numerous countries. 50 percent of the Arctic basin is made up of continental crust – which not only includes the surrounding continents, but also the sea beds and shores of the surrounding oceans. This continental crust is the source of the plant, animal, and sedimentary matter that sinks to the bottom of the Arctic ocean.
During the Cretaceous period, sedimentary matter from the landmasses surrounding the region we now call the Arctic, coupled with the sediments left behind by submarine volcanic plateaus, sunk to the ocean floor. This resulted in the formation of a sedimentary rock called shale. Even sediment from farther-off oceans and seas, having flowed into the Arctic ocean, brought in different minerals and added to the oceanic soil. This layer of shale became the base for the formation of fossil fuels.
Over the span of millions of years, the Arctic continental crust experienced numerous anoxic events – times of dire depletion of oxygen within the ocean. This lack of oxygen, coupled with the sinking of organic sediment, the extremely high temperature in the volcanic Arctic Deep, and the presence of shale, resulted in the formation of natural gas and other fossil fuels.
Just like sandstone in deserts, shale has the porosity and permeability to store natural gas for years. It is this gas that many countries around the world are vying to get their hands on.
The reason for the high demand in Arctic natural gas is simple. Arctic natural gas reservoirs are probably the only remaining reservoirs that haven’t been tapped yet; meaning, they could hold the key to the Earth’s future energy needs.
But while the Arctic holds immense promise for renewable energy, there are still numerous challenges when it comes to extraction. Its remoteness, sub-zero surface temperatures, shifting ice formations, and the fact that 84% of Arctic natural gas is in the offshore continental shelf and deep ocean (not on Arctic land) make the region very difficult to access. Then there is the problem of transporting natural gas from the Arctic to markets across the world – a task which will require specialized (and expensive) technology.
Yet, these issues aren’t stopping the world from attempting to access natural gas in the Arctic. Studies of the region have shown that a large part of the natural gas deposit in the Arctic is on the Asian side of the region. Countries like Russia and China, which are located on the Asian side, have already started work on natural gas extraction. The Power of Siberia – a pipeline that connects Russia’s Siberian natural gas reservoirs to China – is expected to start operations in 2020, a move that will revolutionize the natural gas industry by setting an example of co-operative Arctic mining.
At the Atlantic and Pacific side, countries like Canada, the US, Finland, Iceland, Norway, and Denmark are also working on projects that can make Arctic natural gas more accessible and inexpensive. Their target areas are the Pacific, Atlantic, and Arctic basins surrounding the Arctic circle.
Desert and Arctic Natural Gas Reservoirs Can Power the World for Years to Come
The world’s deserts and the Arctic region offer immense scope for the renewable energy industry. While a large part of the deserts has been mined for natural gas, there is still plenty left in deeper layers of the soil. Additionally, places like the Grand Canyon are still not tapped to their full potential and can offer a lot more.
The Arctic is today the most exciting frontier in the renewable energy sector. The summer season, coupled with other changes in global temperature, is accelerating the melting of sea ice, giving natural gas companies more opportunities to safely extract gas from the region.
As countries around the world come together to create a safer and more holistic natural gas extraction process for both deserts and the Arctic, we may see an increase in natural gas extraction in these two regions soon.