MULTIHOLE WELL CONSTRUCTION METHOD Russian patent published in 2015 - IPC E21B7/08 

FIELD: oil and gas industry.

SUBSTANCE: multihole well construction method involves opening of windows in a casing pipe of the main well shaft, drilling of upper and lower additional shafts till design depth using the appropriate whipstocks, at least one of which is of a removable type, attachment of additional shafts by shanks from the main shaft using a fixing agent shutting off a branching interval. Sequential lowering after branching into side shafts on a pipe string of shanks attached to it through a disconnecting assembly is performed so that the upper part of the above shank and the disconnecting assembly can be located inside the casing string of the main shaft. After pumping of the fixing agent, disconnection by means of a disconnecting device of the pipe string and hardening of the fixing agent is completed, drilling-out of the disconnecting assembly and the upper part of the shank is performed, interaction of additional shafts is arranged and development of the well is performed. Opening of windows is performed by cutting-out of sections of the casing pipe of the main shaft of the well at the branching interval of additional shafts till lowering of whipstocks. An upper whipstock is of a removable type. Prior to lowering, shanks are additionally provided with one or more filters, above which there installed is a coupling of stepped cementing with a packer below the pumping hole. After installation of the shank by means of the coupling a fixing agent above the filter or filters is pumped. Drilling-out of the fixing agent is performed at two stages: first, with a drilling bit of smaller diameter to the whipstock, and then, with a drilling bit of large diameter to the lower edge of the whipstock. After the hardened fixing agent of the upper additional shaft is drilled out, the upper whipstock is removed from the well by means of a removal device, thus providing interaction with the lower additional shaft.

EFFECT: excluding penetration of non-filtered well fluid into the main shaft and onto the surface.

2 cl, 9 dwg