Salt Domes – An Economically Significant Geological Formation

Enlarged view of salt crystals

What is a Salt Dome?

A salt dome is a geological formation deep under the surface of the Earth. It is a vertical column of salt which protrudes upwards into the layer of sediments called the caprock. Salt formations are typically horizontal, but when in a sedimentary basin where a thick layer of salt is covered by a layer of sediments of heavy mineral, salt formations can rise vertically. 

How is Salt Domes Formed?

A phenomenon known as diapirism takes place beneath the surface of the Earth. It allows lighter material to force its way upwards through denser material. In the case of a salt dome, salt has a lower density compared to the rocks above it. When a gravitational force, tectonic force, and a combination of various other forces act upon salt, this results in the deformation of salt. As a result, the salt flows upwards like a viscous liquid. 

For the formation of a salt dome, the pressure on the salt must be high enough to allow the salt to penetrate through the layer of sediment above it. Once the salt begins to flow, the process will continue as long as the pressure on the salt is more than the forces acting against it, but once the forces are in equilibrium, the flow of salt will stop. 

When conditions are favorable, salt domes can grow thousands of feet above their core. They can also reach the surface of the Earth and result in the formation of salt glaciers. The formation of salt domes does not occur overnight. It is a long process which can take centuries. The process begins in an isolated marine inlet. When the water evaporates, it leaves concentrated salt. Geologists believe that the evaporation process should occur multiple times. This will help achieve the required concentration of salt essential for creating a salt dome

Once the large deposits of salt are created, wind and other external forces will come into play. Over time, sediments are deposited on the salt. Once the sediments have completely covered the salt formation, the forces acting on the salt will become stronger. Since salt is a mineral with lighter density, it will find its way upwards through the sediments. 

Size of the Salt Domes 

Salt domes are often very large structures. The diameter of the salt dome can range from ½ a mile to over five miles. The origin or the parent rock from which the salt dome rises is typically found thousands of feet below the surface. A typical salt dome rises at least a mile from its origin and some are known to be higher than six miles.

Economic Significance of Salt Domes 

Salt domes are important due to various reasons. They serve as a reservoir for oil and gas. They are also a critical source for sulfur and salt. Once the salt is extracted, the remaining salt dome holes can be used as an effective underground storage and waste disposal site for hazardous waste. 

Oil and Gas Reservoirs 

Salt domes have a unique significance in the oil and gas industry. As the salt is rising vertically, it exerts pressure on the rocks above it. The caprock, which is the layer of sediment above the salt, is arched upwards. This upward arch serves as a structural trap and can reserve oil and gas. As the caprock is arched upwards, oil and gas migrate towards the salt dome. Salt is an effective trap rock as oil can come to rest up along the salt. 

This upward arching of the rock and collection of oil and gas in the arch allows better flow rates of hydrocarbons. This helps in the extraction and recovery of fossil fuels trapped along the salt dunes. The extraction of hydrocarbons along the salt dunes is more cost-effective and environmentally friendly compared to conventional drilling. A single salt dome can have numerous reservoirs of oil and gas at various depths and locations around the salt dome. 

A Source of Salt and Sulfur 

Since salt domes are salt formations, they can be exploited through mining. Salt is used as an essential raw material in numerous industries. It is widely used in the chemical industry and for treating snow-covered highways. Apart from commercial use, salt also has domestic applications as well. 

Another important mineral that can be recovered from salt domes is sulfur. Sulfur is not a part of the salt dome but an important component of the caprock. It occurs as a crystalline material and is known to be formed as a result of bacterial activity. The caprock of certain salt domes contains enough sulfur that can be recovered economically. 

The process of recovering sulfur from salt dome involving drilling a well and treating the rock with superheated water and air. However, as of now, this method of recovering sulfur is not cost-effective. Therefore most of the sulfur which is produced today is a byproduct of refining hydrocarbons. 

Underground Storage and Waste Disposal 

When the salt, sulfur and hydrocarbons are extracted, this leaves large holes which can be used for underground storage. Some of the mines which are developed into salt domes are sealed and can be used for the storage of oil and gas. In the US and Russia, salt domes also serve as state reservoirs of helium gas. This is because salt is the only type of rock that has very low permeability. As a result, it can hold the tiny atoms of helium gas. 

Since salt has low levels of permeability, it also restricts the flow of any type of liquid into the soil. These properties make salt domes very effective for the disposal of hazardous radioactive waste.


Salt domes are a distinct geological formation with great economic value. Though it takes centuries to form, once formed, humans can continue to benefit from them for years.  

Top Five Rice Producing Nations in the World

Rice crop in a field

Rice is one of the top three food crops grown in the world. Based on production and use of land, rice only follows maize and sugarcane. Around 78% of the total crop grown in the world is consumed by humans as food.

While it continues to be a dinner table essential, it has many other uses as well. It is used as a gluing agent in various industries and is primarily consumed in the Eastern part of the world, specifically Asia. Additionally, rice has some nutritional benefits, especially brown rice.

It is one of the very few crops which need a lot of water to grow. Hence, it is grown in areas where water is available abundantly. Rice, along with maize and wheat, is the main source of calories for almost 50% of the world’s population. It is cheap and easily accessible, and many different varieties of rice are available. Since it is a staple crop for more than half of the world’s population, rice cultivation is increasing every year.

However, with the ever-growing population, the consumption of rice is also on the rise. The rate is much higher than the cultivation rate. Another major issue with rice cultivation is the shortage of water. Thus more and more farmers are relying on genetically modified crops that can be grown in a shorter period with less need for water. 

Rice is mainly grown in the Asian belt with countries like China, India, Pakistan, and Bangladesh securing a place in the top ten list of the world’s largest rice producers. But the interesting fact is the same countries are also the world’s largest consumer of rice. 

It is estimated that the demand for rice will rise to 555 million tons in the current year as opposed to 490 million tons in 2019. It is also expected that Asians will be responsible for consuming 67 % of the total yield. An overview of top rice-producing countries is as follows. 


China tops the list of the world’s largest producers of rice. The largest producer of rice is also the biggest consumer, as it also tops the list of countries with the largest population. Rice, being a dietary staple in China is essentially part of every Chinese meal. The country alone produces 35% of the top world’s rice yield. China manages to produce around 197 million tons of rice every year.

The crop is grown on more than 30 million hectares of land. With technological advancements in genetic engineering and increased use of genetically modified foods, the yield of rice per hectare in China is much higher compared to other countries in the world. China consumes almost 148 million tons on its own. Whereas the rest is exported to other parts of the world. 


India secures second place on the list of top rice-producing nations in the world. The cultivation area of rice in India is more than in China. Rice is grown on 44.1 million hectares in India as opposed to 30.17 million hectares in China. However, due to the use of genetic engineering and hybrid seeds, the annual rice yield in China is more than that in India.

The annual yield in India is 148 million tons compared to 197 million tons in China. More than 50% of the Indian population feeds on rice as a primary food and consumes around 99 million tons of rice domestically. This also makes India the second-largest consumer of rice. 

Moreover, the government supports rice cultivation by providing subsidies on rice seeds, fertilizers, and machinery. Together India and China account for more than 55% of the total rice grown in the world. 


Third on the list is Indonesia. Compared to the two rice giants, rice cultivation in Indonesia is substantially less. The crop is grown on approximately 12.2 million hectares of land. 65 million tons of rice is produced annually in Indonesia, but the country only consumes 37.5 million tons. The rest of the rice crop is exported to other parts of the world. 

The global demand for rice is increasing very rapidly and Indonesia, which is the largest Muslim country, is playing an important role in meeting this demand. 


Bangladesh is the fourth-largest producer of rice and has the highest per capita rice consumption in the world. The crop is grown on 12 million hectares of land.  The annual rice production in Bangladesh is 47 million tons. Unlike the top three producers of rice where rice is grown on a large field, Bangladesh rice cultivation is usually owned and managed by families.

The annual consumption in Bangladesh is around 40 million tons. Thus, there is practically nothing left to export. Rice is considered as a food security in Bangladesh mainly because of the high consumption rate.


The fifth-largest producer of rice is Thailand. With cultivation on an area of fewer than 10 million hectares, the country manages to produce more than 30 million tons of rice. However, the consumption of rice is around 10 million tons domestically. Hence, Thailand is one of the major exporters of rice around the world. Thailand is the largest exporter of rice with annual rice exports of around 18 million tons. The jasmine basmati rice grown in Thailand is one of the most famous varieties in the world.





Top Five Countries with Largest Reserves of Natural Gas

Stove with gas lights running

Natural gas is considered to be one of the most essential fuels used in households. Natural gas, which primarily comprises methane is commonly used in oven and stoves in almost every country of the world. Chemically, natural gas is composed of one part of carbon and four parts of hydrogen. It is much lighter in weight compared to oxygen. This is the reason why it evaporates very rapidly. Natural gas has a pungent smell which can be noticed quite easily. 

This gas is an important fossil fuel and originally natural gas reserves were classified as associated and non-associated reserves. Associated gas reserves are found along with oil reserves. They can be extracted or transferred back to the reservoir. Non-associated gas reserves are gas reserves found independently. However, as of now, we categorize natural gas into two different types; conventional natural gas and unconventional natural gas, also known as shale gas. These two distinct types of natural gas are found in different types of rock formations. Regardless of the type, natural gas is primarily used as a domestic fuel. It also has wide industrial applications and is also used as an alternative fuel for vehicles. 

Today the global reserves of natural gas are estimated to be 7,121.4 trillion cubic feet. 80% of the total proven natural gas reserves are found in eight countries. It is expected that there are other reserves of natural gas, which are not proven so far. From the data of 2018, the top five countries with the largest reserves of natural gas are: 


Russia holds the largest reserves of natural gas in the world. As of 2018, the country’s reserves are estimated to be 1,688.23 trillion. This makes up for around 24% of the global reserves of natural gas. Hence, Russia has a big stake whenever the global gas prices fluctuate. More than 50% of the Russian gas reserves are located in the cold region of Siberia, specifically in the Nadym-Pur-Taz (NPT) region of the upper-western Siberia. The three largest gas fields in Siberia are Yamburg, Urengov, and Medvedev, which account for nearly 45% of the total country’s gas output.

Gazprom, a state-run company, is responsible for more than 80% of the gas production in the country. This is one of the biggest known stakes in a natural resource for a single entity as this accounts for 20% of the world’s gas production. 


Second on the list with the largest gas reserves is Iran. The country which has always been under political instability and sanctions has managed to capitalize on its natural resources. Iran is not only rich in natural gas but possesses many other natural resources. 

Iran holds almost 1,200 trillion tons of natural gas, which accounts for almost 18% of the total global gas reserves. The largest gas field in the world, the South Pars is located in Iran. More than 80% of the Iranian gas reserves are non-associated gas reserves. This means that they are not found along with reserves of crude oil. 60 % of the country’s total gas reserves are located in the ocean as South Pars extends to Qatar and a large part of it is in the ocean. This gas field is responsible for more than 25% of the country’s total gas output. Other major gas fields in Iran include the North Pars, Kish, and Kangan. 

Recently, Iran discovered a new natural gas reserve, which according to its oil ministry holds 19 trillion cubic feet (tcf) of the resource and could potentially produce 400 million barrels, worth about $40 billion. However, increased sanctions by the US may prove cumbersome and delay or even halt their natural gas exports from this area. We’ll have to wait and see how this plays out.


Qatar, a Middle Eastern nation, which is the largest supplier of LNG liquid natural gas comes third on the list of largest gas reserves.. The country possesses around 175.5 billion cubic meters of proven natural gas reserves. The South Pars located in Iran extends to Qatar. This is the world’s largest offshore field holding the largest reserves of non-associated gas. Another major gas field located in Qatar is the North field. Also, the Barzan gas project played an important role in increasing the output of gas in Qatar since its completion in 2015.

Saudi Arabia

The global oil-producing giant and a leading member of OPEC comes fourth on the list. The country holds over 7.9 billion cubic meters of gas reserves which makes up almost 4% of the world’s total proven gas reserves. 

The Famous Ghawar onshore, Ghawar offshore, Safaniya, and Zuluf fields produce more than 50 % of the total gas output. These gas fields account for more than 55% of the total reserves in the country. There are many nonassociated gas fields in the country as well. They include the Karan field, Arabiyah field, and Hasbah gas fields. 


5th on the list is Turkmenistan. The country also holds proven gas reserves of 7.57 billion cubic meters which account for almost 4% of the world’s supply. The reserves are located mainly in the Amu Darya Basin in the South East and the Murgab South Caspian Basin which is located in Western Turkmenistan. The Dauletabad field is by far the oldest and the largest gas field in the whole country. 

The country lacks proper infrastructure and there have been very few developments when it comes to the oil and gas sector.  

There are some other major players when it comes to global reserves of natural gas. This includes countries such as Venezuela, Nigeria, Australia, Iraq, China, and Israel with exports planned to go to Egypt and Jordan shortly. Additionally, Israel recently signed a deal with Greece and Cyprus to export natural gas to these countries as well.