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sichuan online reporter wang ruoye

natural gas hydrate, commonly known as combustible ice, looks like ice and burns when exposed to fire. it is "hidden" in the deep sea or in the permafrost on land. its reserves are huge, twice as much as fossil energy such as coal and oil. it is considered to be one of the ideal clean energy sources in the 21st century. however, the environment in which combustible ice is located is very complex, and mining is not easy.

on september 10, the provincial science and technology conference awarded 247 projects the 2023 sichuan science and technology award. among them, 6 scientific and technological achievements won the sichuan technology invention award. one of them, the "key technology and equipment research and application of underground methane hydrate solid fluidization downhole double-layer pipe mining" project hosted by southwest petroleum university, won the first prize of the 2023 sichuan technology invention award.

after 10 years of research, the project has filled a gap in the field and supported the successful implementation of the world's first solid fluidized production trial of natural gas hydrates. how "hardcore" is this technology? the project team "revealed"

filling the gap: putting new ideas for developing combustible ice into practice

in layman's terms, combustible ice is a loose solid that uses water molecules as cages to imprison gas molecules such as nitrogen, carbon dioxide, and methane.

for a long time, the common mining method internationally has been to extract methane hydrate after it is vaporized in the reservoir. however, when it is mined on a large scale, the methane hydrate will vaporize and dissipate upward into the seawater. existing technology has never been able to overcome the risks of explosion, shipwreck, tsunami, submarine landslide, etc. caused by this.

in 2012, zhou shouwei, a famous expert in offshore oil development engineering, proposed a new development idea, which is to crush the combustible ice into fluidized form and then suck it into the wellbore for controllable lifting through solid fluidized mining. "to put it simply, the combustible ice is crushed, recycled into a double-layer 'suction straw', and then 'sucked' out, turning the uncontrollable into controllable," said wang guorong, the project team leader and professor of the school of mechanical and electrical engineering at southwest petroleum university.

how to implement this development idea? focusing on the basic theory gap of solid fluidization underground mining of methane hydrate, the lack of dedicated experimental platforms and integrated underground mining tool systems, southwest petroleum university, together with cnooc and other units, jointly launched the "key technology and equipment research and application of undersea methane hydrate solid fluidization underground double-layer pipe mining" project.

"what we are doing in this project is to move this development idea towards engineering and turn it into a set of practical technologies, equipment and process flows," wang guorong introduced.

a project team discussing technology. photo provided by the interviewee

under the guidance of academician zhou shouwei and professor liu qingyou of chengdu university of technology, wang guorong led his team to successfully develop, from scratch, solid fluidization underground integrated mining equipment for shallow seabed methane hydrate, and also established a new double-layer pipe mining method and a dynamic simulation experimental method and system for mining, providing new technology and equipment support for the continuous large-scale development of methane hydrate.

"this is a difficult road of exploration from '0' to '1', because it is a brand-new mining concept in the world, lacking design theory and design basis. what technical indicators the tools should achieve, how to verify, test and evaluate the performance, etc., all problems are unknown." wang guorong said that he encountered many "bottlenecks" in the middle, but they were eventually broken through one by one.

supporting trial production: using technological innovation as a weapon to safeguard national energy security

in may 2017, my country successfully conducted a test production of methane hydrate in the shenhu area in the northern part of the south china sea, which also marked that my country became the first country in the world to achieve continuous and stable gas production in the test production of methane hydrate in the sea. it is worth mentioning that the successful test production in the shenhu area of ​​the south china sea was muddy silt sand type natural gas hydrate, which accounts for more than 90% of the world's resources and is the most difficult to develop.

the successful trial production was supported by the technology and equipment developed by wang guorong's team. seven years have passed since the first trial production, and wang guorong still remembers many details. "that was the first time the whole set of process flow and supporting equipment were put into the 'test room'. we stayed at sea for more than 20 days. after repeated research and deduction, we refined the construction details and finally achieved solid fluidization trial production at a water depth of about 1,300 meters."

in the third year after the first completion of the trial production of methane hydrate, my country's trial production of methane hydrate in its waters once again achieved good results. the total gas production and average daily gas production in the second round of trial production once again broke the record, and the core technology of horizontal well drilling and production in deep-sea shallow soft formations was mastered.

the two rounds of trial production have different focuses. the first round focused on completing "exploratory trial production" to solve the problem of "whether it can be mined safely and continuously". the second round of trial production completed "experimental trial production" to solve the problem of "how to increase the scale of gas production", which is an extremely critical step in the industrialization process of natural gas hydrates. "the second trial production is a progression of the first one. the trial production is more difficult. we have also refined the details of the process technology, continuously improved the process and equipment, and ensured the trial production." wang guorong said.

"this award is an affirmation and recognition of our research work over the past decade. as scientific and technological workers, we should use scientific and technological innovation as a weapon to provide solid technical and equipment support for maintaining national energy security." wang guorong said, "we are currently working in two directions. one is to make the entire set of technical equipment and process flow move towards engineering, and at the same time try to jointly exploit methane hydrate with shallow, medium and deep oil and gas to further reduce costs and increase production."

(sichuan online)