Breakthrough Research on Salt-Gypsum Rock Formations Yields New Insights into Drilling Fluid Dynamics

Strategic Insights -

Scientists at China University of Petroleum Beijing Karamay have made significant contributions to the field of drilling technology with their latest study on salt-gypsum rock formations. The research focused on the problems of borehole shrinkage and pipe sticking caused by creep in salt-gypsum rock formations during deep well drilling. Through multi-field coupling creep experiments and numerical simulations, the team constructed a nonlinear creep constitutive model and determined the critical value of liquid column pressure for borehole shrinkage. The study's findings have critical implications for preventing borehole wall instability and have been widely recognized as a significant breakthrough in the field.

Key Takeaways:

  • The research team conducted multi-field coupling creep experiments on deep salt-bearing gypsum mudstone to address the problems of borehole shrinkage and pipe sticking caused by creep in salt-gypsum rock formations.
  • A nonlinear creep constitutive model was constructed based on the Drucker-Prager criterion, allowing for the determination of the critical value of liquid column pressure for borehole shrinkage through numerical simulation.
  • The study found that salt-gypsum rock is more prone to plastic flow under high temperatures and confining pressure, and that the creep constitutive equation can accurately describe three-stage creep.
  • The numerical simulation revealed a nonlinear relationship between drilling fluid density and borehole shrinkage, with a critical safe density range of 2.1-2.3 g/cm3.
  • The research results provide an experimental basis and quantitative method for the dynamic regulation of drilling fluid density in deep gypsum rock formations, and have significant engineering implications for preventing borehole wall instability.

Statistics:

  • The shrinkage rate exceeds 1.47% when the drilling fluid density is 1.0 mm when = 2.4 g/cm3.
  • The critical safe density range for drilling fluid is 2.1-2.3 g/cm3.
  • The stress exponent m = 2-5, and the time exponent n decrease linearly with the increase in deviatoric stress.

Sources:

  • Study On the Construction of a Nonlinear Creep Constitutive Model of Salt-gypsum Rock In the Bayan Deep and the Critical Value of Wellbore Shrinkage Liquid Column Pressure. Processes, 2025;13(9):2747.
  • NewsRx. Study Findings from China University of Petroleum Beijing Karamay Broaden Understanding of Technology (Study On the Construction of a Nonlinear Creep Constitutive Model of Salt-gypsum Rock In the Bayan Deep and the Critical Value of Wellbore ...). Mathematics Week. November 4, 2025; p 475.