METHOD OF PREVENTING HYDRATES FORMATION IN OIL WELL (VERSIONS) Russian patent published in 2002 - IPC

FIELD: oil producing industry; applicable for preventing hydrates formation in oil wells drilled in regions of permafrost rocks. SUBSTANCE: according to the first version, subject to detection in shut-in or operating marginal well drilled in permafrost rocks are zones of rock local temperature drop with determination of temperature values on internal wall of flow string and depth of oil dynamic level. Temperature in annular space is increased to above temperature of hydrates formation of formation oil by value depending on determined temperature values and depth of oil dynamic level. High values of the latter require increase of temperature value in annular space. In preferable version method is realized by passing of electric current through cable consisting of sections with different electric resistances. It is possible to decrease pressure in annular space from working to atmospheric values with increase of temperature in annular space. According to the second version, pressure in annular space is reduced to preset level in shut-in or operating marginal well drilled in permafrost rock. Detected preliminarily are zones of rock local temperature drop with determination of temperature values on internal wall of flow string and depth of oil dynamic level. Pressure in annular space is decreased to below pressure of hydrates formation of formation oil by value depending on determined values of temperature and oil dynamic level depth. Invention provides for reduction of power consumption and increase of efficiency of preventing hydrates formation in tubings and annular space of shut-in and operating marginal wells drilled in regions of permafrost rocks due to creation of conditions ensuring selective temperature and pressure effect on hydrates. EFFECT: higher efficiency. 4 cl, 6 dwg