Study on the Plugging Rules of Cement Sheath Fractures Under Sustained Casing Pressure in Gas Wells,Western Sichuan Area
Sustained casing pressure is common in abandoned wells of Western Sichuan area,which makes the ef-fective plugging of cement sheath fractures crucial to prevent natural gas leaks and groundwater contamination.Under sustained casing pressure plugging fractures becomes more challenging,requiring higher standards for seal-ing technologies and materials.This paper uses a high-temperature and high-pressure core multi-parameter measur-ing instrument to carry out simulation experiments to test the flow performance of fracture plugging agents.It uses numerical simulation methods to study the flow patterns of flexible plugging agents in fractures under different pressure differences,and evaluates the flow performance of conventional oil well cement and flexible plugging a-gents under sustained casing pressure in abandoned well.The results show that increasing displacement pressure does not effectively enhance the flowability of flexible plugging agents for fracture widths ≤ 207 μm,while for widths ≥383 μm,it significantly improves their flowability and plugging efficiency.For fracture widths ≤446μm,increasing displacement pressure does not effectively enhance the flowability of conventional oil well cement.At smaller fracture widths,the flow of the plugging agent is laminar,distinct,smooth,and orderly.Using fluctua-ting pressure injection methods can improve the plugging efficiency of plugging agents.This paper provides strong experimental and data support for testing and evaluating the flow performance of plugging agents under sustained annular pressure in abandoned wells,offering a theoretical basis for the rational selection of plugging agents in plugging operations.
sustained casing pressureabandoned wellflexible plugging agentconventional well cementplugging effect
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