METHOD FOR MULTIPLE HYDRAULIC FRACTURING OF FORMATION IN HORIZONTAL SHAFT OF WELL Russian patent published in 2013 - IPC E21B43/267 C09K8/90 

FIELD: oil and gas industry.

SUBSTANCE: method involves lowering of packer on a pipe string with its further mounting in the well, formation of cracks opposite filters in series at different intervals of productive formation opened with horizontal shaft, supply of hydraulic fracturing fluid through the filter installed in each of the parts of horizontal shaft, which corresponds to each of those intervals, with insulation of the rest of its parts. According to the invention, direction of horizontal shaft is determined relative to direction of minimum primary stress. Then, interval subject to formation hydraulic fracturing (FHF) is isolated from the rest sections of horizontal shaft by installation of double packers. Then, a valve arranged inside the pipe string between double packers opposite the filter is opened. If direction of horizontal shaft is parallel to direction of minimum primary stress, hydraulic formation fracturing is performed by pumping of fracturing fluid with formation of transverse cracks relative to horizontal shaft with further reinforcement of transverse cracks by pumping of the fluid with aluminosilicate proppant with gradual increase of its fraction from 20/40 mesh to 16/30 mesh. If direction of horizontal shaft is perpendicular to direction of minimum primary stress, hydraulic formation fracturing is performed by pumping of fracturing fluid with formation of horizontal cracks relative to horizontal shaft with further reinforcement of horizontal cracks by pumping of the fluid with light-weight proppant with fraction of 20/40 mesh. After FHF is completed, the well is closed for the process pause during half the hour. After that, an adjustable choke is installed on pipe string at the well head and waste proppant fluid is drained from the formation via the pipe string on the well head before the valve is closed. By adjusting the above choke during the drain process, the value of pressure in pipe string becomes by 2-3 MPa lower that the value of pressure when the well is opened after the process pause. Packer is removed and pipe string is moved to the other part of horizontal shaft. The above FHF process performed in horizontal shaft of the well is repeated depending on number of intervals of horizontal shaft.

EFFECT: improving the efficiency of hydraulic fracturing of rocks.