How geology is helping Middle East oil and gas explorations
Study of ancient rock structures is vital for the success of ongoing oil and gas exploration, like the recent discovery of a well in a gas field in Sharjah
A young Omani geologist, Asad, conducts tours of the famous Wadi Shab while planning to work in his profession. The new geological park, just opened at Jebel Buhais in Sharjah, reminds us of how important the region’s rocky foundation is to its past, present and future. Hopefully it will encourage more people to study this vital science.
The Jebel Buhais centre tells the story of how Sharjah, and the whole Arabian continental plate, drifted over the last hundreds of millions of years from south of the equator to the northern subtropics, and separated from Africa along the line of the Red Sea, an incipient ocean. As Arabia collided with the Iranian land mass, a slice of the ocean crust and upper mantle some 10 kilometres thick was forced on to land. Such an occurrence, known as an ophiolite, is the only way we can directly study the structure of the oceanic rocks. The ophiolite in Oman and the northern UAE is the best preserved and exposed in the world.
Such rocks are rich in minerals, including chromite and copper. In antiquity, Magan, now modern-day Oman, was the source of copper for the Bronze Age civilisations of Mesopotamia. Modern mining is now an important part of Oman’s efforts to diversify its economy.
The geological folds around Jebel Buhais are also found in the subsurface, where they form traps for oil and gas. The study of such structures is vital for exploration such as last month’s well in Sharjah that found the emirate’s first new gas field in 30 years. The UAE is a mosaic of folds related to the Oman mountains, older features inherited from the assembly of the Arabian continental plate, and domes created by subsurface salt deposits, also major traps for petroleum.
Significant earthquakes are rare in the UAE and Oman, but we often feel milder shocks from quakes taking place in the mountain belts in Iran and Pakistan, formed by ongoing continental collisions. A huge tsunami struck the northern Omani coast a thousand years ago, triggered by a tremor in the Makran belt on the northern side of the Arabian Sea. Evaluating such geohazards is crucial for setting building costs and establishing emergency warning systems.
The Jebel Buhais geological display also features a wide range of fossils from the limestone rocks that overlie the ophiolite. Some, such as marine snails, are familiar; some are long-extinct — such as the ammonites, spiral-shelled relatives of squid, and rudists, large cup-shaped shells whose remains lie abundantly on the park’s slopes.
These give insights into past climates and the quality of reservoirs for oil, gas and water. The Gulf owes its mineral wealth and its modern history to the unique confluence of organic-rich rocks from ancient tropical seas that form hydrocarbons when deeply buried — giant structures to trap oil and gas, and porous reservoir rocks from which it can be tapped by wells.
Elsewhere, geoscientists have mapped the jigsaw puzzle of the continents to show exactly where they fitted together into Pangaea — “all Earth”. Such clues have encouraged exploration in places like Guyana, the newest significant oil-producing country, by analogy with once-adjacent petroleum basins in Africa.
Over the past few hundred thousand years, Sharjah went through a series of drier and more humid phases, related to the ice-ages in more northerly latitudes. When sea-levels were low as water was locked up in polar ice-caps, early humans were able to cross the Red Sea to settle in southern Arabia. Water that collected underground in rainy times was the key source for agriculture and life up to the modern period. Date palms and bananas grow luxuriantly in the water trapped in the narrow Wadi Shab in Oman.
Geologists are now called on to apply this study of ancient climates to the near future. The accumulation of carbon dioxide in the atmosphere from burning fossil fuels and forests is warming the Earth, risking returning to a climate hotter than modern humans have ever experienced. Careful study of fossils, sediments and the geochemistry of rocks gives vital indications of just how much warming we can expect from a certain amount of carbon dioxide.
Geology also has an essential role to play in tackling climate change. Novel green energy technologies such as solar panels, wind turbines, electric motors and batteries require new and exotic minerals. Nickel, for instance, present in the ophiolite belt, is used in many battery designs.
Carbon dioxide can be put back into the ground instead of being released into the atmosphere. Abu Dhabi has the world’s first large-scale carbon capture project applied to an industrial facility, the Emirates Steel plant, and Adnoc plans to have more. With similar technologies to oil and gas production, this requires mapping suitable underground storage reservoirs with sealing rocks to prevent the carbon dioxide leaking out, and monitoring its flow through the subsurface.
This brings us back to ophiolites. Their minerals react rapidly with carbon dioxide in the atmosphere to form calcium carbonate, the main constituent of limestone. The Oman ophiolite is full of veins created in this way. Geoscientists Juerg Matter and Peter Kelemen from Columbia University have proposed that we could store 4-5 billion tonnes of carbon dioxide annually, of the 36.6 billion tonnes emitted worldwide, by drilling into the ophiolite rocks and circulating hot water saturated with carbon dioxide.
Geology in the Gulf of course concerns petroleum, but also covers crucial topics such as mining, water, earthquakes, climate and the environment. Jebel Buhais and other sites in the region remind us that geoscience is about the deep past but also the near future. A fascinating and crucial range of careers are open to the young Omani geologist Asad, and others like him.
Robin M. Mills is CEO of Qamar Energy, and author of The Myth of the Oil Crisis
Published: February 3, 2020 07:30 AM