METHOD OF DRILLING OF BRANCH WELLBORE FROM CASED DEVELOPMENT WELL Russian patent published in 2002 - IPC

FIELD: drilling of oil and gas wells, particularly, methods of drilling of branch wellbore. SUBSTANCE: essence of invention consists in that a part of casing string is removed and cement bridge is installed in formed aperture. Branch wellbore is start drilled from this cement bridge due to screwing in body of lower section of screw hydraulic downhole motor to which extensible bit is secured which is extended and fixed under pressure of mud. In this case, prior to start drilling of branch wellbore, wellbore of parent well is extended above point of spudding within interval of distant section flow string. EFFECT: higher quality of tapping of producing horizontal and accelerated process of drilling of secondary wellbores from drilled branch wellbores. 2 dwg