METHOD DETERMINING OPTIMUM CONDITION OF OPERATION OF WELL IN ROCKS FROZEN FOR MANY YEARS Russian patent published in 2001 - IPC

FIELD: oil and gas production industry. SUBSTANCE: method can find use for operation of oil, gas and gas condensate wells in zone of presence of rocks frozen for many years. Season-acting cooling devices- thermal stabilizers are put into tubes-satellites placed immediately beyond direction of well. Standard gas-dynamic investigations are conducted. Thermal-physical properties are determined and natural temperature in zone of rocks frozen for many years is measured. Computational mathematical model of geotechnical system " well-thermal stabilizer-rocks frozen for many years " is developed with use of obtained data. This model is based on solution of two-dimensional differential equation of heat conduction in Cartesian coordinates with mobile phase boundary in inhomogeneous medium by numerical methods. Thermal interaction of well with rocks frozen for many years with specified parameters of geotechnical system is modeled on basis of results obtained at preceding step which reflect condition of thermal field of system and condition of thermal field of rocks frozen for many years in well-head zone of well by moment of switching off of thermal stabilizers with coming of warm period is determined. Later computational mathematical model of geotechnical system " well-rocks frozen for many years " based on solution of two-dimensional differential equation of heat conduction in cylindrical coordinates with mobile phase boundary in anisotropic medium by numerical methods is created. Then thermal interaction of well with rocks frozen for many years is modeled for various temperatures of produced fluid in warm period during which cooling system is switched off. Temperature on boundary " cement-rocks " in well-head zone of well is found per each version of modeling for end of warm period and is compared with temperature of beginning of phase transfers of rocks. In case of equality of computational temperature on given boundary and temperature of beginning of phase transfers of rocks temperature of extracted fluid which is maximum permissible temperature for warm period at which rocks frozen for many years do not thaw is registered. Optimum condition of operation of well is determined proceeding from obtained temperature of fluid. EFFECT: provision for stability of structure, for reliable and safe long-time operation of well under conditions of expansion of rocks frozen for many years under minimal capital outlays, operational expenses and energy consumption. 4 dwg, 1 tbl