METHOD FOR PRIMARY OPENING BY DRILLING OF HORIZONTAL SHAFT IN FRACTURE TYPE OF OIL AND GAS SATURATED CARBONATE RESERVOIR UNDER CONDITIONS OF ABNORMALLY LOW FORMATION PRESSURES Russian patent published in 2016 - IPC E21B21/00 E21B33/13 E21B43/02 

FIELD: oil and gas industry.

SUBSTANCE: invention relates to oil and gas industry, specifically to technology of construction of deep wells, oil and gas production and, in particular, to primary opening of horizontal shafts of oil and gas saturated fracture carbonate reservoir with abnormally low formation pressure. Method comprises cyclically, after complete opening of each absorbing fractured interval using a drill bit, in interval of absorption zone, arranging on "equilibrium" viscous a colmation acid-soluble stack. This temporarily isolates absorption zone. Then method comprises lifting string bottom and lowering drilling tool with "funnel" into absorption zone. After that, viscous colmation stack is washed at 15 l/s. Method then includes pumping acid-resistant proppant in design volume in said absorbing fractured interval of horizontal well. Then wellhead is sealed and at pressure not exceeding 3 MPa, providing minimum repression and intake, proppant is injected in mode of injection of 15 l/s into bottomhole formation zone. Method then includes repeatedly placing in open horizontal borehole viscous colmation acid-soluble stack on "equilibrium". This covers previously fixed cracks in zone of absorption of drilling mud. Lowering-lifting operation is performed for changing "funnel" on bit. Primary opening by drilling horizontal shaft in fractured carbonates is continued to absorption zone. After that, operation of fixation of fractures is repeated.

EFFECT: maintaining filtration properties of fractured carbonate reservoir during reduction of formation pressure and creation of large depressions during operation of said fracture collector.

1 cl, 1 ex