METHOD FOR DETERMINATION OF FORMATION INTERVALS WITH VISCOUS OR HIGHLY VISCOUS OIL Russian patent published in 2015 - IPC E21B47/00 

FIELD: oil and gas industry.

SUBSTANCE: invention is referred to oil industry and may be used to determine intervals in the well log with viscous or highly viscous oil. The method for determination of formation intervals with viscous or highly viscous oil includes geophysical survey in the well and analysis of obtained data. The survey is performed at the stage of hole director drilling, propagation distance is assessed preliminary for all logging instruments and the instrument with the least propagation distance is selected; the borehole is drilled with drill bit having diameter that allows surveying by the instrument with the least propagation distance, the borehole is worked out with the drill bit and contractions in the borehole are eliminated, the borehole is filled in with clay drilling mud, at geophysical surveying in the well compensatory dual neutron logging plus gamma-ray logging and carbon/oxygen logging are performed, logging is doubled in the assumed interval of formation with viscous or highly viscous oil, the instruments are removed from the well, the borehole is drilled out with the drill bit as per hole director diameter, and at analysis of the obtained data intervals with high porosity and increased carbon/oxygen ratio and symmetric reduced calcium/silicon ratio are selected.

EFFECT: invention allows determining formations with viscous or highly viscous oil in the well log.

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