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          CN 51-1183/TE


Your Position :Home->Past Journals Catalog->2020 Vol.6

Application and Design Method of Downhole Throttling Technology in Ultra-High Pressure Gas Wells
Author of the article:Yu Yang, Wang Weilin, Peng Yang, Tan Hao, Dong Zonghao, Zhou Wei
Author's Workplace:Engineering Technology Research Institute of PetroChina Southwest Oil and Gas Field Company, Chengdu, Sichuan, 610017, China
Key Words:Ultra-high pressure; Downhole throttling; Two-stage; Hydrate; Pressure drop; Temperature drop

Downhole throttling technology is a gas production technology that uses downhole throttler to prevent hydrate formation. At present, surface wellhead heating and multi-stage throttling gathering and transportation technology are widely accepted in ultra-high pressure gas wells. Yet, there are such issues as complex surface throttling process and inconvenient operation by personnel. The maximum throttle pressure difference of the existing downhole throttler is 70 MPa, which limits the application of ultra-high pressure gas wells. To address the above problems, two schemes of Underground Plus Ground Two-Stage Throttling and Two-Stage Underground Throttling are proposed. Taking an ultra-high pressure gas well in Sichuan-Chongqing area as a case, the feasibility of two-state throttling scheme is demonstrated by modeling. The results show that: (1) With Underground Plus Ground Two-Stage Throttling, when the production is low, the temperature after ground throttling is lower than the surface hydrate formation temperature, and a heating device is required. At high production rates, the temperature after ground throttling is higher than the surface hydrate formation temperature, and no extra heating devices is required. (2) When two throttling nozzles are installed downhole, the calculated temperature after throttling is higher than the hydrate formation temperature to ensure that no hydrate is generated in the wellborn. Therefore, the downhole two-stage throttling is feasible. (3) With optimum design, the sizing difference of two downhole throttling nozzles will not lead to the failure of another throttling nozzle. So, the target of downhole two-stage throttling can be well met. The research results can provide basis for field application of downhole throttling technology in ultra-high pressure gas wells.

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