Solution and Analysis of Wellbore Temperature and Pressure Field Coupling Model under Lost Circulation

Abstract

The fluid in the annulus is in a variable mass flow state under the lost circulation condition, significantly affecting wellbore pressure distribution and the heat transfer efficiency between wellbore and formation. Therefore, based on the hydrodynamics and energy conservation law, a coupling model of transient wellbore temperature and pressure field under lost circulation conditions is established, which fully considers the casing program, bottom hole assembly, and heat source generated in drilling, as well as the influence of the temperature and pressure coupling in wellbore on the physical parameters of drilling fluid. The calculation results of the model in this paper are in good agreement with the field measured data and the previous research results, which verifies the rationality and accuracy of the model in this paper. The effects of the loss rate and the lost circulation zone location on the wellbore temperature and pressure distribution are analyzed, and the variation rule of the physical parameters of drilling fluid under the lost circulation condition is studied. The numerical simulation results show that the density and viscosity of drilling fluid in the annulus and bottom hole pressure increase with the increase in the circulation time; the annulus temperature decreases gradually with the increase in cycle time and tends to become stable after 8 h of the cycle. The annulus temperature and bottom hole pressure decrease with the increase in loss rate and closeness of the loss zone to the well bottom. When the loss zone is in the upper open-hole section, an inflection point consistent with the location of the loss zone appears on the annular temperature difference curve between the loss circulation and the nonloss circulation, and the position of the loss zone can be judged according to the inflection point.

Laws of Hydration Heat of Cement and Hydrate Stabilization in Shallow Formations of Deep Seawater

“…For a long time, researchers in various countries have mainly focused on numerical simulation methods − and modeling analysis methods − to study the temperature field and temperature-stress field of cemented sheaths in wellbore. Generally, based on the relevant theories of heat transfer, elastic-plastic mechanics, and the actual working conditions of cement sheath sealing in cemented wells, the mathematical model to analyze the temperature field of the wellbore is established by taking the case of wellbore-casing-cement sheath-surrounding rock as the research object.…”

Numerical study of temperature–pressure coupling model for the horizontal well with a slim hole

“…Marshall and Bentsen 30 provided four partial differential energy equations applicable to the drilling column, within the drilling column, in the annulus, and in the formations to solve the non-steady state heat transfer in the wellbore. Zhu et al [31][32][33] considered the influence of high temperature on wellbore drilling fluid circulation under different circumstances, and established a transient wellbore flow model suitable for dry hot rock, drilling fluid leakage or gas drilling. However, in the above methods, the physical properties of mud, such as density and viscosity, are treated as constants.…”