CARBONATE FORMATION HYDRAULIC FRACTURING METHOD Russian patent published in 2012 - IPC E21B43/26 

FIELD: oil and gas industry.

SUBSTANCE: method involves lowering to the well of tubing string with packer and its further fit, lowering to tubing string of flexible tubing string below lower end of tubing string; pumping of water-insulating cement via flexible tube; hydraulic fracturing of carbonate formation with bottom water. Lower end of flexible tubing string is lowered to the level of water-oil contact (WOC); space is sealed between tubing string and flexible tubing string, insulation of bottom water is performed in carbonate formation by pumping of water-insulating cement via flexible tubing string with well filling from working face to WOC level. After that, space between tubing string and flexible tubing string is unsealed and flexible tubing string is lifted so that its lower end is 1-2 metres below roof of carbonate formation; after that, total volume of fracturing fluid is determined as per analytical expression. Space between tubing strings and flexible tubing strings is sealed and the first portion of fracturing fluid is pumped to flexible tubing string in the quantity of 60-70% of total fracturing fluid volume under the pressure of not more than 25 MPa and at the speed of not more than 2 m³/min. After that, the rest fracturing fluid volume is pumped to flexible tubing string in 3-5 cycles in turn with pumping of propping agent. As the latter there used is 25% inhibited chlorhydric acid. Volume of acid is determined depending on thickness of productive part of carbonate formation based on volume of 0.2 m³ of acid per 1 m of formation thickness per each pumping cycle. After the last pumping cycle is completed, acid is flushed with water solution of surface active substance in volume of flexible tubing string with further exposure during 1-2 h. Then, flexible tubing string is removed from tubing string and the well is brought into operation.

EFFECT: simpler and more effective method.

3 ex, 2 dwg