METHOD FOR DETERMINATION OF INTERVALS WITH GAS-BEARING FORMATIONS IN WELL Russian patent published in 2015 - IPC E21B47/00 

FIELD: oil and gas industry.

SUBSTANCE: invention is referred to oil and gas industry, in particular, to geophysical surveying of wells, and it may be used for evaluation of location of gas-saturated terrigenous and carbonate rocks. During determination of intervals with gas-bearing formations in the well surveying 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, formation density logging (FDL) is performed together with compensation neutron log (CNL) and gamma-ray logging (GRL), logging is doubled in the assumed interval of formation. The instruments are removed from the well, the borehole is drilled out with the drill bit as per hole director diameter. During analysis of the obtained data intervals with high values of CNL and symmetrical low values of density curve for FDL and GRL are selected.

EFFECT: increased accuracy for determination of intervals with gas-bearing formations in the well.

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