WATER FLOW ISOLATION TECHNIQUE IN UNCASED HORIZONTAL BOREHOLE SECTION OF PRODUCING WELL Russian patent published in 2015 - IPC E21B33/13 E21B43/00 E21B47/00 

FIELD: oil and gas industry.

SUBSTANCE: water flow isolation technique in uncased horizontal borehole section of the producing well includes removal of pumping equipment from the well, running of flow column to the well and injection of water isolating material. Upon removal of the pumping equipment from uncased horizontal borehole of the producing well an additional offshoot with horizontal section is drilled below this uncased horizontal borehole from the producing well thus opening water-bearing formation. At that bottomhole of the horizontal offshoot is made longer and at distance of 50m from bottomhole of the uncased horizontal borehole of the producing well. Then coil tubing is run down up to the bottomhole of the additional offshoot and by axial movement of coil tubing from the bottomhole zone up to the well mouth with simultaneous injection of water isolating material to the coil tubing the water-bearing formation and additional offshoot are isolated up to interval of its sidetracking from the producing well. At that mixture of high-viscous and carbonaceous oil wit ratio of 70% to 30% is used as water isolating material and high-viscous oil with temperature of 60-70°C is used as restraining material. Then coil tubing is removed from the auxiliary well, pumping equipment is run down to the uncased horizontal borehole of the producing well and the producing well is input into production. In process of operation of the producing well periodical sampling of the product is performed. When water cut of the product exceeds the permitted value pumping equipment is removed from the well and geophysical study of the horizontal borehole of the producing well is performed and inflow interval is detected in water-bearing formation. Thereafter coil tubing complete with packers is run down to the well, the required interval is shut off from both sides and interval of the uncased horizontal borehole of the producing well is shut off by injection of high-viscous emulsion represented by mixture of high-viscous and carbonaceous oil with ratio of 70% to 30%. At that water isolating screen formed in the well is impermeable for water but passes oil as viscosity of emulsion is reduced sharply when diluted by oil. Then pumping equipment is run down again to the uncased horizontal borehole of the producing well and operation of the well is continued again.

EFFECT: improved quality and workability of water shutoff works.

3 dwg, 1 tbl