METHOD FOR HYDRAULIC FRACTURING OF PRODUCTIVE FORMATION WITH CLAY LAYER AND GAS-BEARING HORIZON Russian patent published in 2017 - IPC E21B43/267 C09K8/80 

FIELD: oil and gas industry.

SUBSTANCE: invention can be applied for the hydraulic fracturing treatment (HFT) of a formation containing a clay layer with a gas-bearing horizon. Method involves carrying out the perforation in the productive formation interval of the well oriented in the direction of the main maximum stress, lowering the tubing string (TS) with the packer to the well, seating the packer, performing the hydraulic fracturing treatment (HFT) by means of pumping the hydraulic fracture liquid via the tubing string with the packer through the perforation interval into the production formation with obtaining the fracture and its further fixation by a propping agent, relieving the pressure in the well, releasing the packer and its extracting with the TS from the well. The oriented perforation is carried out using a hydromechanical perforator with an orienting sub, the HFT process starts with pumping the hydraulic fracturing fluid, which is represented by a crosslinked gel, to create a fracture in the productive formation, after which the fracture formed is developed by pumping linear gel with the density of 1,150 kg/m³ with an ultralight proppant with the density of 1,050 kg/m³ of the 40/80 mesh fraction with the weight of 3 tons with the concentration of 200 kg/m³, then the fracture is fixed by pumping crosslinked gel with the proppant of 20/40 mesh fraction or 12/18 mesh fraction, depending on the permeability of the production formation, in batches with the stepwise increasing of the proppant concentration by 100 kg/m³, starting from 200 kg/m³ up to 900 kg/m³. Wherein the crosslinked gel with the proppant of 20/40 mesh fraction is pumped into the productive formation with the permeability from 0.01 to 100 mD during the fracture fixation, while in the productive formation with the permeability from 100 to 500 mD the crosslinked gel with a proppant of 12/18 mesh fraction is pumped during the fracture fixation.

EFFECT: improving the reliability of the fracture creation and development in the presence of a clay layer and a gas-bearing horizon above the production formation, increasing the method efficiency; reducing the hydraulic resistance in the perforation interval, reducing the length and complexity of the technological process of the method implementation.

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