FIELD: physics.
SUBSTANCE: method of determining water saturation in a subsurface formation involves determining an invasion depth in the formation from a plurality of measurements made within a wellbore drilled through the formation. The measurements have different lateral depths of investigation in the formation. Carbon and oxygen in the formation are measured at substantially the same longitudinal position as the position of determining the invasion depth. The measured carbon and oxygen and the invasion depth are used to determine water saturation in a substantially uninvaded part of the formation.
EFFECT: high accuracy of data on saturation of formations with fluids.
19 cl, 4 dwg
