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A professor at Marietta College and two other inventors have received U.S. patents for two procedures that increase the hydrocarbon recovery from shale reservoirs and sandstone reservoirs.
Ahmed Algarhy helped develop the innovative methods with Mohamed Soliman of the University of Houston and Lloyd Heinze of Texas Tech University. The patent submissions were made four years ago.
"Hydrocarbon recovery from both conventional and unconventional reservoirs is very low," said Algarhy, who joined the Marietta College Petroleum Engineering faculty in 2018.
The hydrocarbon recovery factor for conventional reservoirs is typically between 5% and 15% after primary recovery and between 35% and 45% after secondary recovery, he said.
The hydrocarbon recovery factor for organic shale reservoirs is typically between 5% and 10%, and around 70% of the hydraulic fractures created in such reservoirs do not produce, Algarhy said.
The first strategy, called Complex Toe-to-Heel Flooding, increases oil recovery from sandstone formations under specific reservoir conditions. Toe-to-Heel Flooding is an improvement upon conventional Toe-to-Heel Waterflooding and uses gravity segregation to increase the oil production rate and the total oil recovery, Algarhy said.
The second completion strategy, Optimized Zipper Frac, increases hydrocarbon recovery from organic shales. Organized Zipper Frac is an improvement upon Zipper Frac, Alternate Fracturing and Modified Zipper Frac because it uses ballooned fractures to create stress shadows that minimize stress anisotropy and thereby maximize near-wellbore complexity and production rate, Algarhy said.
"A horizontal well completion method known as zipper fracturing has been rapidly adopted over the last 10 years by companies in the United States. Instead of drilling and hydraulically fracturing one well at a time, the zipper method involves drilling multiple wells from a pad site and then hydraulically fracturing a stage in one well, while getting ready for the next, as wireline and perforation operations take place in another," Algarhy said. "The multi-well completion method earns its name from the zipper-like configuration of the fracture stages from wells drilled with relatively tight spacing."
Many companies in the U.S. use the completion method on almost every new pad site they drill into, saving tens of millions of dollars per year while accelerating the development of their well inventories.
"But the big prize may be that zipper fractures are increasing initial production and estimated ultimate recovery rates when designed so that the fractures stimulate the most reservoir volume possible," Algarhy said.
Algarhy worked in hydraulic fracturing design and implementation from 2003-12014 before he got the chance to complete his doctorate in petroleum engineering at Texas Tech.
"I wrote a proposal to Dr. Soliman, who is now in charge of the petroleum department at the University of Houston, and Lloyd Heinze, a professor at Texas Tech, and we agreed to develop these two new techniques as part of my Ph.D. work," Algarhy said.
"These two techniques help increase the oil and gas recovery and thus help secure more hydrocarbons for the U.S. and make our country more energy independent."
Algarhy, director of PioPetro, a non-profit educational project, hopes the procedures will help the U.S. to some day achieve energy independence.
An assistant professor, Algarhy teaches production and completion, geomechanics, and unconventional reservoir evaluation and development. Algarhy received the regional distinguished achievement award for petroleum engineering faculty for the eastern North America region in 2021.
Algharhy has a Ph.D. and master's of science in petroleum engineering from Texas Tech, a master's of science in petroleum engineering, natural gas engineering postgraduate diploma and a bachelor's of science in mining engineering from Cairo (Egypt) University.
He has more than 11 years of oil and gas industry experience with operation and service companies that focus on hydraulic fracturing, geomechanics, and unconventional reservoirs evaluation and development.