METHOD FOR WELL CONSTRUCTION Russian patent published in 1994 - IPC

FIELD: well drilling. SUBSTANCE: method includes drilling of well, forming side working in well walls at the depth of lowering of casing string. Workings are formed for each intermediate casing string with height ensuring force for adhesion of cement stone to each casing string which counteracts the pushing out force. Casing string is run into well. Prior to injection of grout into each intermediate casing string, hydraulic seal in form of viscous fluid with corrosion inhibitors is injected in amount enough to fill hole clearances of these strings above side workings. Then, grout is injected. Producing formation is perforated before running tubing string into well. After lowering of tubing string, hole clearance of this string above producing formation is filled with viscous fluid to form hydraulic seal with density ensuring hydrostatic pressure exceeding formation pressure. In so doing, side workings are additionally formed in top and bottom of producing formation. Besides, when exposing formations liable to hydraulic fracturing and losses of mud, injected to said formations is viscous fluid - hydraulic seal of density less than that of viscous fluid - hydraulic seal injected below these formations. Hole clearance above producing formation is filled with viscous fluid-hydraulic seal featuring density ensuring hydrostatic pressure exceeding formation pressure by 10-5% . Before lowering of tubing string, producing formation may be perforated. Tubing strings may be provided with packer. EFFECT: higher reliability of isolation of hole clearance and provision of recovery of casing string. 5 cl, 1 dwg