METHOD OF DETECTING GAS-BEARING FORMATIONS IN WELLS Russian patent published in 2009 - IPC E21B47/00 E21B49/00 

FIELD: physics; measurement.

SUBSTANCE: present invention pertains to geophysics, in particular to geophysical methods of surveying wells, for detecting gas-bearing formations and can be used in reservoir management of hydrocarbon deposits. The method of detecting gas-bearing formations in wells involves measurement of the natural acoustic field along the axis of the cased column of the well in three or more given frequency bands and drawing graphs based on the measurement results. The natural acoustic signals are measured using two orthogonally placed sensors, the axes of detection of which lie perpendicular to the wall of the well. The amplitude levels of acoustic signals and their ratios are evaluated. If the amplitude of acoustic signals in the highest frequency band exceeds amplitude values in the lowest frequency band, and the ratio of acoustic signals from two sensors at the highest frequency is not equal to one, then gas-bearing formations are present. The depth intervals of the gas-bearing formations are determined from the maximum level of acoustic signals recorded at the highest frequency and maximum deviation of their ratios from one on the graphs.

EFFECT: increased efficiency and reliability of detecting gas-bearing formations in cased wells.

1 dwg