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

FIELD: oil and gas industry.

SUBSTANCE: analysis of service water is performed, gelling agent is tested for solubility in water and structure formation. If the result is satisfactory, gelling agent is dissolved in water and tested again for structure formation; if results are satisfactory, clay stabiliser, demulsifier and destruction regulating component is added to solution of gelling agent in water. The obtained solution is pumped to the well, and decomposer and cross-linking agent is added to the solution during pumping process, thus forming fracturing fluid. Volume of the well is replaced with fracturing fluid, pumping is stopped and pressure decay is recorded. Pumping of fracturing fluid is restored with working flow rate per hydraulic fracturing. Fracturing fluid blanket is pumped with volume of 3 to 6 m³. Then, there performed is trial sequence of fracturing fluid with proppant in the volume of up to 1 m³ with concentration of 30 to 200 kg/m³ and again fracturing fluid without proppant in the volume of 1.5-1.8 m³. Fracturing fluid is forced through in the volume equal to the volume of tubing string, zone under packer to the roof at perforation interval and 2-4 m³ more. Forcing-through is stopped and pressure decay is recorded. Intensity of wellhead pressure reduction is recorded and processed. The obtained data is processed; data on operating efficiency of fracturing fluid, value of pure pressure, formation stress gradient, time and pressure of fracture closing, pore pressure in manifold, hydraulic pressure losses at perforation interval and bottom-hole part of formation is obtained. Adaptation of design data on hydraulic fracturing process to the obtained test pumping processing data is performed on the basis of the obtained data. Updated data is used for re-calculation of three-dimensional model of hydraulic fracturing and performance of specified version of hydraulic fracturing. Initial plan of the main hydraulic fracturing process is changed by changing initial data on mining-and-geological coefficients for the one obtained with the programme after test pumping is performed. The main hydraulic fracturing process that was changed is performed. When the main hydraulic fracturing process that has been changed is performed on the basis of the made calculations, the required volume of service water is taken, gel is prepared and test is performed. If the test results are satisfactory, hydraulic fracturing process is performed in compliance with the changed design, where volume of final forcing-through is determined as sum of volume of tubing string and zone under packer to the roof of perforation interval. When rise of wellhead pressure is detected during pumping of trial sequence of fracturing fluid with proppant by the value of 1 to 2.5 MPa, volume of pumped proppant of small and average fraction of 20/40, 16/30 and 16/20 mesh is increased for minimum concentrations of 30 to 120 kg/m³ to 800-1000 kg per stage, and efficiency of this activity is evaluated as per reduction of wellhead pressure as this sequence of proppant passes through perforation zone, and when pressure is decreased by 1 and more MPa, the conclusion is made that hydraulic connection with formation has been improved, and hydraulic fracturing process shall be performed according to the planned parameters. When there are no signs of recovery of connection with formation, hydraulic fracturing plan shall be changed until the required result is obtained.

EFFECT: improving monitoring quality of hydraulic fracturing process and expedition of well placing on production.

2 cl, 2 ex, 1 tbl