QNRF Newsletter Archive

Raising concrete standards for oil and gas wells

Whenever a company finds a target to mine oil or gas, environmentalists and residents on that land throw their arms in the air. There is no disputing the potential damage these projects could cause the environment. A big reason for this is that the wells can leak. These wells are lined with pipe that is sealed by concrete. Researchers are now working on an evolutionary race between testing methods and material improvements to make leaking wells a thing of the past.

“There should not be any cracks or anything. Why? If there is a crack, gas will come up and this can result in fire and explosion. It can also leak into the environment and the water table,” said Dr Mahmood Amani, Associate Professor in the Petroleum Engineering Program at Texas A&M University at Qatar. “We can [develop ways to] tell if this cement could crack or fail or if it can stand the type of pressure and temperature and forces that will be acting on it.”

Dr Amani and his team are working on a novel method for testing the cement under extreme temperatures and pressures—it’s a method adapted from another technology within the oil and gas sector.

Cement sheath failure types under investigation.
“What we have done is we have tested cement in a way that nobody has tested it before,” Dr Amani explained. “We have adapted equipment that was for a different purpose—to test drilling fluids at pressures of up to 40K PSI and up to 600 degrees fahrenheit. It is the highest rated viscometer in the world … no other testing equipment exists within this temperature and pressure range and it was built especially based on our orders.”

The equipment that Dr Amani’s team developed was built in a German machine shop. Two testers exist—one at Texas A&M’s College Station campus in the US and one in Qatar.

“So part of the testing we did here and part was there and we validated with both of the machines,” Dr Amani said. “Now that this testing is complete, we have a patent application … we hope that this can become a standard testing procedure to bring integrity to cement so that it won’t crack even under harsh, repeated conditions of high pressure and temperature. Such a test does not exist right now.”

The question then begs—will these enhanced testing methods drive the needed improvements in cement itself? As it turns out, Dr Amani and his team will be happy to stand on both sides of the evolutionary race between improved material standards and the tests that drive them.

“The next research that I am doing with a partner of mine in Houston involves damage-tolerant and self-healing cementing materials for oil wells—we just submitted a proposal yesterday to see if we can prove if a cement can crack or not crack under the harsh conditions,” Dr Amani explained. “This researcher has worked on materials in the US that are patented, but we are going to be testing them under the harsh conditions that we can create here with our machine, and we keep changing the material to see what kind of cement mixture, based on what kind of recipe, can stand the pressure and temperature that our machines expose it to.”

This work is of course pertinent to Qatar’s massive gas industry. The extremes that the team’s equipment simulates are especially important in a part of the world where heat and corrosive, salty conditions threaten material damage.

“In Qatar’s North Field they are working through five layers,” Dr Amani said, “and if they want to go below that … when they go deeper the temperature is higher, the pressure is higher, so the conditions are harsher, so we need to make sure that we have a cement design that can withstand the conditions if we want to drill any deeper.”

Dr Amani said that without the QNRF funding behind these projects, none of the testing at this level would be possible. He is grateful for the support on this project and others he has been involved in over his years as a researcher in Qatar. He is especially impressed by the country’s dedication to the future of research based on early-education and experience programs, namely QNRF’s Undergraduate Research Experience Program.

“I have been involved in ten funded projects, and as a results I have worked with 35 students who have received real training, and some of them have received training to the degree that they finished number one in competitions.

On this cement project alone, Dr Amani has produced seven publications. Additionally, he and a colleague published a review paper a year ago on the effects of high pressure and temperature on oil and gas wells. They presented this paper in Kuwait and since that time it has been in the top ten most downloaded research papers in the petroleum industry—ranking above 10 on Onepetro.org for the past year.

NPRP 09-489-2-182
Investigation on Long-Term Stability of Casing-Cement-Rock Systems Exposed to Variable Loads with Application to Well Integrity Management

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