Method of measuring horizontal flow speed of fluids in earth formations penetrated by a wellborehole
AssigneeTexaco Inc.
InventorsDan M. Arnold, Hans J. Paap, Hubert D. Scott
Life of this patent
Estimating the term…
Abstract
The horizontal flow rate of fluid in permeable earth formations is measured by the in situ creation of a radioactive tracer isotope having a predetermined decay life time and decay mode. Measurements at different time intervals following the creation of the tracer isotope of the decay radiation may then be interpreted in terms of the horizontal movement of fluids past a well borehole. Tracer isotopes to be created are selectively provided for measuring both relatively fast and relatively slow expected values of horizontal flow speed.
Claims10
A method for determing the location and flow rate of earth formation fluids moving in a horizontal direction past a well borehole, comprising the steps of:
- irradiating the earth formations in the vicinity of a well borehole with fast neutrons for a predetermined length of time to neutron activate at least one selected tracer element having a known radioactive half life and comprising a portion of the earth formation fluid moving past a well borehole;
- moving a gamma ray detector past the earth formation which has been irradiated and detecting a first count rate signal representative of gamma radiation caused by the radioactive decay of said selected tracer element;
- waiting a predetermined selected length of time and then again moving said gamma ray detector past the earth formation which has been irradiated and detecting a second count rate signal representative of gamma radiation caused by the radioactive decay of said selected tracer element;
- and
- combining said first and second count rate signals according to a predetermined relationship to derive an indication of the horizontal flow rate of earth formation fluid past the well borehole.
Dependencies are inferred from the claim text.