A method for calculating the safe density window of hydrate formations considering mud cake
By establishing a model of mud cake, hydrate formation seepage and heat transfer, and combining finite element software and the Coulomb-Mohr criterion, the effective stress distribution of the wellbore was calculated, which solved the wellbore instability problem, provided a safe density window for drilling fluid, and reduced economic losses during the drilling process.
CN118627424BActive Publication Date: 2026-05-26CHANGZHOU UNIV
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHANGZHOU UNIV
- Filing Date
- 2024-06-14
- Publication Date
- 2026-05-26
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Figure CN118627424B_ABST
Abstract
This invention discloses a method for calculating the safe density window of hydrate formations considering drilling fluid action. A multi-field coupled thermal-fluid-solid-chemical model is established, taking into account the effects of mud cake seepage at the wellbore and the decomposition of natural gas hydrates. The simulation results present the distribution of pore pressure, temperature, and solute concentration in the drilling fluid around the wellbore after drilling fluid intrusion. Based on the solution results of the multi-field coupled model and combined with the Coulomb-Mohr failure criterion, a method for calculating the safe density window of hydrate formations under drilling fluid action is further established. This method more comprehensively considers the influence of various factors on wellbore stability during hydrate extraction, making the model results more accurately reflect the actual formation conditions and providing a basis for the design of drilling fluid anti-collapse performance during hydrate formation drilling.
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