Method for determining oil and water saturation in earth formation surrounding a borehole
US5055676A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 9, 1990 |
| Grant date | Oct 8, 1991 |
| Priority date | — |
| Expiry date | May 9, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01V5/101
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and an apparatus for determining the hydrocarbon saturation S.sub.o in an earth formation surrounding a borehole, and/or the hydrocarbon saturation C.sub.b in said borehole, comprising: irradiating the formation with a source of neutrons of sufficient energy to interact with atoms of the formation and the borehole, according to inelastic neutron reactions; detecting the resulting gamma rays at a near detector and a far detector; expressing the measured carbon (C) and oxygen (O) yields respectively as a first and second linear function of S.sub.o, S.sub.w the water saturation in the formation, C.sub.b and/or C.sub.o water saturation in the borehole; combining the respective carbon and oxygen yields (C.sup.n, O.sup.n) for the near detector, and the respective carbon and oxygen yields (C.sup.f, O.sup.f) for the far detector so as to form the differences C.sup.n -O.sup.n and C.sup.f -O.sup.f ; and solving for the unknowns S.sub.o and C.sub.b. Alternately, in case either S.sub.o or C.sub.b is known from another source, one can use a single detector.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.