METHOD OF DECREASE OF WATER INFLOW TO HORIZONTAL WELLS Russian patent published in 2015 - IPC E21B33/138 E21B43/20 

FIELD: oil and gas industry.

SUBSTANCE: in the method of decrease of water inflow to horizontal wells comprising a selection of the production horizontal well, injection of the working agent in it and start-up of well in production, the laboratory studies are pre-conducted using the core of the considered layer, during which the probability of migration of fine clay particles from pores under the effect of the working agent and plugging by them of pore channels, pre-determined by minimum 1.5 times decrease of phase water permeability of the reservoir, is revealed. The working agent used for injection is water with total mineralization of salts no more than 5 g/l and with the density no more than 1080 kg/m³ - soft-salted water and/or water with the hydrogen indicator pH more than 8.0 d. units - alkaline water. The injection of soft-salted and/or alkaline water is performed into the selected production well and into the closest, located at the maximum distance 500 m, injection well with the initial flow rate different from each other by no more than 20% and greater, than the flow rate into the injection well of waste or reservoir water before the activities. The injection of soft-salted and/or alkaline water is conducted during the maximum time five days. Then the production well is put into operation at the same modes, like before injection, and the injection well is injected by waste or reservoir water at the flow rate before activities. The cycles of injection of soft-salted and/or alkaline water are repeated at growth of water content of the well by 10-30% with reference to the water content after the previous cycle of injection and withdrawal of injected water. Meanwhile the volume of injected fresh-salted and/or alkaline water in each subsequent cycle is increased.

EFFECT: improvement of efficiency of isolation of water inflow to horizontal wells and increase of coefficient of oil deposit recovery.

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