METHOD OF WELL-ROCKS SYSTEM STABILIZATION IN CRYOLITIC ZONE Russian patent published in 2003 - IPC

FIELD: construction and operation of producing wells in cryolitic zone for preservation of rocks of wellhead zone in frozen state and functional usefulness of well during entire term of its operation. SUBSTANCE: method includes determination of quantity and location of thermal stabilizing members, heat insulating properties of heat-insulating member and parameters of temperature conditions of well-rocks-atmosphere system. For this purpose, mathematical modeling of heat exchange is effected in calculated region, and annular heat-insulating member enclosed in heat-transmitting layer consisting of rock of thermal stabilizing members is located round upper part of well structure strings. Heat exchange mathematical modeling in calculated region is effected by solving spatial nonlinear problem of nonstationary heat exchange of well string structure with rocks and atmosphere with consideration of phase transitions of pore moisture and thermodynamic equilibrium of freezing of water-containing mass in closed volumes depending on concentration of impurities in water and pressure in it. Temperature conditions of well-rocks-atmosphere system is set to preserve frozen state of heat transmitting layer and its enclosing rocks and conditions of preservation of temperature of water-containing mass located in closed volumes of well structure annular space exceeding temperature of well structure destruction with freezing of water-containing mass. Parameters of temperature conditions of well-rocks-atmosphere system in course of well operation are monitored and in case of detection of tendency of temperature distribution in well-rocks system to level destructing casing strings, heat physical parameters of well structure and thermal stabilizing members are respectively controlled as thermal stabilizing members provide for heat supply and its elimination. Spatial nonlinear problem of nonstationary heat exchange is solved by use of special equation. EFFECT: higher efficiency of stabilization of well heat conditions in cryolitic zone. 4 cl, 4 dwg