Solar thermal EOR is gaining traction in the Middle East, allowing companies to harness the power of the sun to produce oil, instead of burning precious gas and oil, but what is it exactly, and what are the benefits?
Enhanced oil recovery (EOR) is hitting its stride as many countries globally, as well as in the Middle East, are looking to enhanced oil recovery (EOR) methods to squeeze the very last drop of oil out of their wells.
“Proven EOR technologies are being adapted in new, smart ways. Technologies are constantly evolving from research to commercial applications, making EOR projects more economical,” explains Omer Gurpinar, technical director of enhanced oil recovery from Schlumberger.
Solar thermal EOR is changing the face of enhanced oil recovery, bringing with it benefits such as a reduction in the amount of oil or gas that is utilised to extract oil, and harnessing the power of the sun to do so.
“At the moment primary production in most of the world is in decline and demand is increasing so there is a shortfall. That shortfall will be filled in by new production and about half of that production will be heavy oil and about half of that will be thermal recovery, so solar is a very big market,” states Rod MacGregor, president & CEO at GlassPoint Solar.
In a nutshell, solar EOR uses solar arrays to concentrate the sun’s energy to heat water and generate steam. The steam is then injected into an oil reservoir to reduce the viscosity of thin, heavy crude, then allowing it to flow to the surface.
“EOR using steam is using 23% of some countries gas production, injecting steam is well proven, but the challenge is that it uses massive amounts of energy. In the Middle East, gas is a scarce commodity; outside Qatar and Iran there is no natural gas and most of these countries have a gas shortage, which is where solar comes in. In summer every square inch of ground gets one kilowatt of energy and we can harness that,” explains Daniel Palmer, VP of Sales at GlassPoint Solar.
Steam produced by solar is identical to steam produced by gas or oil. Solar thermal EOR produces the same pressure, temperature and steam quality.
“Companies can’t tell if it is solar steam or gas steam, and that was the point, to make it compatible with the existing infrastructure, the same electricity, the same infrastructure, water and produces the same output,” explains MacGregor.
More oil is produced in the long term out of each well when using solar, as compared to using oil or gas, making it an attractive proposition for the Middle East region, according to Glasspoint.
Article continues on next page …
When the well is first drilled and steam is injected into it, nothing much happens for the first few years as the rock underground has to heat up; a very long process. Once the rock heats up and oil starts to flow out of those producer wells, oil flow increases, reaches a plateau for a few years, and then it starts to decline.
During the decline period gas is still being burned to inject steam into the wells, but the amount of oil coming out of the well is decreasing to a level where it no longer makes economic sense to burn oil or gas to produce oil. The well is then shut down.
“In a solar situation you pay for all your solar system upfront when you buy the equipment, because sunshine is free. Late in the life of the field when the company is not getting much oil out of the ground, solar is not costing anything. There are some maintenance costs, but there are no fuel costs, so you just keep producing,” states MacGregor.
During the lifecycle of an oilfield the ultimate recovery fraction is higher when the company uses solar; ie the company will produce more oil over the lifetime of the field using solar thermal than oil or gas.
A good way of calculating the savings of solar thermal EOR methods, as compared to thermal EOR methods using oil or gas, is to calculate the gas break-even price or GBE. This involves calculating the average price of gas over the field’s lifetime per million btu, when compared to the initial cost of solar set up spread out over the same field’s lifetime.
“In the Middle East region, the calculation for solar EOR usually comes to between $5 and $7 per million btu, if you compare that to fuel costs, which are at $12 to $18 per million btu. You are looking at half the price for solar,” explains Glasspoint’s MacGregor.
To effectively use solar EOR heavy oil must be in production, the field must be in an area with good sunshine, and fuel supply must be consistent. For example, if a country has abundant cheap gas, it probably wouldn’t use solar. Heavy oil production, abundant sunshine and consistent fuel supplies are three factors that are available in the Gulf region.
Another problem with solar thermal EOR is space; there is only so much sunlight that falls on a square metre of land and solar thermal EOR will always be constrained by the available surface area. This is where the efficiency of the solar thermal EOR system you choose comes in; how efficient it is at turning sunlight that falls on a single square metre into steam.
“No matter how efficient your system is, we are still talking about large amounts of land. Most of the oilfields in the Middle East that are considering solar are in the middle of nowhere; they are in the desert with nothing around them for hundreds of miles so the space is there and you aren’t disrupting any one,” says MacGregor.
A big challenge for solar EOR is that while electricity can be moved a long distance, allowing the power company to put their solar power station in a clean and dust free area with little humidity, with an oilfield solar EOR system, steam cannot be pumped thousands of miles, so the solar system must be quite close to the oilfields.
Article continues on next page …
Humid and dusty oilfields can put the brakes on solar thermal enhanced oil recovery. The problem that dust and humidity creates for solar is that dust sticks to the morning dew on the mirrors, then the sun bakes it on. If something is not done, the solar mirrors stop being mirrors and efficiency decreases.
“These solar systems regularly cover 1,000 acres. It’s one of the things holding back deployment of solar in the region,” says MacGregor.
Glasspoint has developed a self-washing enclosed solar thermal EOR system to combat the sand problem.
