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

FIELD: oil and gas industry.

SUBSTANCE: method involves perforation of well walls at well formation interval with channels with the depth that is not less than length of stress concentration zone in rocks from the well shaft; lowering of pipe string with packer; installation of packer above roof of perforated productive formation; pumping of fracturing fluid gel to under-packer zone; creation of formation hydraulic fracturing pressure in under-packer zone and pumping of fracturing fluid gel with proppant to the formed formation crack. According to the invention, formation hydraulic fracturing is performed using different fractions of proppant and two types of fracturing fluid gel; besides, first, total volume of fracturing fluid gel is determined as per analytical expression. Total volume of fracturing fluid gel is divided into two parts, of which 2/3 of that fluid is volume of crosslinked gel, and 1/3 of that fluid is inline gel. Formation hydraulic fracturing process is started from pumping to the well via pipe string of fracturing fluid gel - crosslinked gel with dynamic viscosity of 150-200 sPa till a fracturing crack is formed in the formation. After fracturing crack is created in the formation, the rest volume of crosslinked gel of 2/3 of fluid is pumped in equal portions during 3-5 cycles with addition of proppant with fraction size of 12-18 mesh with flow rate of 1.5-2 m³/min. Proppant is added to crosslinked gel in steps with increase in concentration from 200 to 1000 kg/m³. After that, without interrupting the formation hydraulic fracturing process, inline gel with dynamic viscosity of 30-50 sPa is pumped to the well via pipe string in equal portions during 3-5 cycles to the fracturing fluid; proppant with fraction size of 20-40 mesh is added with stepped increase of concentration from 200 to 1000 kg/m³. After the last portion of inline gel with proppant is pumped to the well pipe string, they are forced to the formation with process fluid. Besides, process fluid flow rate is decreased to 0.5-1 m³/min during 1-3 minutes and pumping with flow rate of 2.5-3 m³/min is recovered again till complete forcing of inline gel with proppant to the formation. Exposure is performed during the period of time, which is required for pumping pressure drop by 70-80%; packer is removed with pipe string from the well.

EFFECT: increasing the method's efficiency owing to increasing the well drainage radius.

3 ex, 2 dwg