METHOD OF HYDRAULIC FRACTURING OF WELL FORMATION Russian patent published in 2013 - IPC E21B43/26 

FIELD: oil and gas industry.

SUBSTANCE: method involves lowering to the well of a tubing string with a packer, creation in the formation with bottom water of a hydraulic fracturing crack by pumping of fracturing fluid, lowering to the tubing string and below it of a string of flexible tubes to lower holes of the perforation interval, pumping of the fracturing fluid with a proppant via the tubing string, and water insulating cement via the flexible tube string in the quantity that is sufficient for filling the lower part of the fracture with water insulating cement till the level of oil-water contact (OWC) with filling of some part of the fracture in the bottom water zone. Before being lowered to the well, the tubing string with a packer is equipped with a perforated branch pipe and an additional packer, which are arranged below the packer. When the tubing string is being lowered, the perforated branch pipe is installed opposite the perforation interval of the water insulating portion of the formation, and setting of packers is performed. The packer is put 5-10 m above the formation, and the additional packer is set at OWC interval at the non-perforated interval of the formation. Flexible pipe string is lowered to the tubing string and below it to the lower openings of the perforation interval. Total volume of the fracturing fluid is determined, the space between the tubing string and flexible tube string is sealed and the fracturing fluid without the proppant is pumped to the tubing string in the volume equal to 0.2-0.25 of total volume of the fracturing fluid so that a hydraulic fracturing crack is formed. Then, water insulating cement is pumped via the flexible tube string in the volume that is sufficient for filling of lower part of the fracture in the bottom part of the formation to OWC interval. In annular space between tubing string and flexible tube string there maintained is pumping of fracturing fluid at the pressure that exceeds by 10-15% the squeeze pressure of the water insulating cement through the flexible tube string, the flexible tube string is lifted a little so that its lower end can be located on one and the same level with the lower end of the tubing string; after that, the rest volume of the fracturing fluid is pumped via the tubing string together with the proppant, and their squeezing is performed with process fluid to the formation. Then, the exposure is performed during the period of the time, which is enough for pumping pressure drop by 70-80%. The flexible tube string is removed from the tubing string, the packer and the additional packer is unpacked, and the tubing string and themselves are removed from the well.

EFFECT: improving the hydraulic fracturing efficiency.

1 dwg