METHOD OF EXTRACTION OF OIL AND OTHER FORMATION FLUIDS FROM RESERVOIR (VERSIONS) Russian patent published in 2014 - IPC E21B43/20 

FIELD: oil and gas industry.

SUBSTANCE: invention group is related to the methods of increase of extraction of heavy or viscous crude oil from an underground reservoir and in variants of its fulfilment is especially related to operations of cold extraction from such reservoir. Substance claim: the method involves oil-bearing reservoir rock and has at least one development well and at least one injection well. The method provides for carrying out secondary recovery operations with the use of displacing fluid; at that, density of extracted oil is within ≤30° API, and the method includes the following operations: (a) overinjection of displacing fluid into reservoir rock with Voidage Replacement Ratio (VRR) from 0.95 to 1.11 until Water-Oil Ratio (WOR) of formed fluids is at least 0.25; and (b) underinjection of displacing fluid into reservoir rock with VRR<0.95 until Gas-Oil Ratio (GOR) of formed fluids is at least twice higher of GOR with dissolved gas of initial oil recovered from a well; at that, during water injection, accumulated VRR is kept within 0.6 to 1.25.

EFFECT: invention facilitates upgraded efficiency of the methods.

48 cl, 15 dwg