FIELD: physics; geophysics.
SUBSTANCE: present invention relates to geophysics and can be used to determine porosity of a formation surrounding a well. According to the present disclosure, drilling mud penetrates a formation by a certain distance which is a function of time. First and second porosity measurements are taken at a first and a second moment in time. The first porosity measurement relates to a type selected for indicating porosity measurement in the presence of a gas different from the second porosity measurement. The first and second porosity measurements are selected to provide almost the same depth of investigation in the formation and experience an approximately proportional effect from the gas.
EFFECT: high accuracy of investigation data.
7 cl, 18 dwg
