HYDRAULIC FRACTURING METHOD OF LOW-PERMEABLE BED WITH CLAY LAYERS Russian patent published in 2012 - IPC E21B43/26 

FIELD: oil and gas industry.

SUBSTANCE: method includes pumping of hydraulic fracturing fluid through the well via tubing with packer into productive formation with the following pumping-in of propping agent. As hydraulic fracturing fluid there used is a water-base foam system that includes: 55-75% of nitrogen, 1% solution of potassium muriate and water solution of surface-active reagent. The process of hydraulic fracturing of formation consisting of productive and non-permeable interlayers begins at initial density of foam system of 0.25 g/cm that is supplied to the formation bottom-hole zone via tubing with the aid of device for hydraulic fracturing fluid with propping agent pumping with gradual increase of pumping pressure till maximum value. Note that the maximum pressure created in the process of formation hydraulic fracturing should be higher than the pressure of hydraulic fracturing of productive interlayers, but lower than the pressure of hydraulic fracturing of clay layers. There formed are the cracks of hydraulic fracturing in the rocks that have the least critical rock breaking gradient. After that the hydraulic fracturing cracks are reinforced by pumping of foam system with propping agent that represents silica sand with sand concentration in foam system from 800 to 1000 g/l with obtaining the end density of foam system to 0.8 g/cm³. After formation hydraulic fracturing the well is closed for process break for 30 minutes. At well mouth there installed is an adjustable nozzle to the tubing and the well is produced to flow. Nozzle adjustment helps to obtain the flow pressure in tubing lower than the pressure at well closing not less than by 1.5-2 MPa.

EFFECT: increase of hydraulic fracturing efficiency.

2 cl, 2 dwg