US 4,729,960 A · Method of prospecting for hydrocarbon deposits

Abstract

Disclosed are methods of prospecting for subterranean deposits of hydrocarbon. Earth samples are taken at various depths in a substantially vertical column of earth overlying an area suspected of containing an underground petroliferous deposit. The magnetic susceptibility of each sample is then measured (or the concentration of maghemite or greigite therein determined) to determine the relative concentration of diagenetic magnetic material therein. The relative concentration data is correlated with depth from the surface to the approximate maximum penetration depth of surface-related oxygen. An anomaly occurring in the curve produced by such correlation demonstrates the likelihood of discovering a subterranean deposit therebelow. The relative concentration of diagenetic magnetic material in the earth's surface within the layer thereof subject to surface water penetration is increased by oxidation of ferrous iron previously reduced from the ferric to the ferrous state by the reducing effect of upwardly migrating hydrocarbons diffusing toward the surface from a subterranean deposit thereof.

Claims37

Dependent claims

The method of prospecting for conditions indicative of subterranean deposits of hydrocarbon comprising the steps of:

(a) determining the approximate maximum depth of diagenetically-formed magnetic materials in a substantially vertical column of earth;
(b) taking earth samples from said substantially vertical column of earth at pre-selected depths from the earth's surface to approximately said maximum depth of diagenetically-formed magnetic materials;
(c) determining the magnetic susceptibility of said earth samples;
(d) correlating the magnetic susceptibility data of said samples to form a curve representative of the distribution of magnetic susceptibility as a function of depth;
(e) comparing the magnetic susceptibility distribution curve to the approximate maximum depth of diagenetically-formed magnetic materials;
and
(f) determining if a discontinuity occurs in the magnetic susceptibility distribution curve above the depth representative of the approximate maximum depth of diagenetically-formed magnetic materials in said vertical column of earth.

4 more elements

The method of estimating the general surface boundary outline of a known subterranean deposit of hydrocarbons comprising the steps of:

(a) taking earth samples at various known depths from the earth's surface in at least one borehole extending from the earth's surface to said subterranean deposit;
(b) measuring the magnetic susceptibility of said earth samples;
(c) correlating the magnetic susceptibilty data of said earth samples to form a curve representative of the distribution of magnetic susceptibility as a function of depth for said borehole;
(d) determining the approximate maximum depth of diagenetically-formed magnetic materials in the vicinity of said borehole;
(e) taking earth samples at various known depths between the earth's surface and the approximate maximum depth of diagenetically-formed magnetic materials in a plurality of substantially vertical columns of earth laterally displaced from said borehole;
(f) measuring the magnetic suseptibility of said earth samples;
(g) correlating the magnetic susceptibility data of the samples from each of said substantially vertical columns to form a curve representative of magnetic susceptibility as a function of depth for each of said plurality of substantially vertical columns;
and
(h) comparing the curves of magnetic susceptibility as a function of depth for each of said plurality of substantially vertical columns to the curve of magnetic susceptibility as a function of depth for said borehole.

6 more elements

The method of estimating the general surface boundary outline of a known subterranean deposit of hydrocarbons comprising the steps of:

(a) taking earth samples at various known depths from the earth's surface in at least one borehole extending from the earth's surface to said subterranean deposit;
(b) measuring the maghemite concentration in said earth samples;
(c) correlating the maghemite concentration of said earth samples to form a curve representative of the relative distribution of maghemite concentration as a function of depth for said borehole;
(d) determining the approximate maximum depth of diagenetically-formed magnetic materials in the vicintity of said borehole;
(e) taking earth samples at various known depths between the earth's surface and the approximate maximum depth of diagenetically-formed materials in a plurality of substantially vertical columns of earth laterally displaced from said borehole;
(f) measuring the maghemite concentration of said earth samples;
(g) correlating the maghemite concentration of the samples from each of said substantially vertical columns to form a curve representative of the relative concentration of maghemite as a function of depth for each of said plurality of substantially vertical columns;
and
(h) comparing the curves of relative distribution of maghemite concentration as a function of depth for each of said plurality of substantially vertical columns to the curve of relative distribution of maghemite concentration as a function of depth for said borehole.

6 more elements

The method of estimating the general surface boundary outline of a known subterranean deposit of hydrocarbons where the earth's surface is covered with a body of water comprising the steps of:

(a) taking earth samples at various known depths from the earth's surface in at least one borehole extending from the earth's surface to said subterranean deposit;
(b) measuring the greigite concentration in said earth samples;
(c) correlating the greigite concentration data of said earth samples to form a curve representative of relative greigite concentration as a function of depth for said borehole;
(d) determining the approximate maximum depth of diagenetically-formed magnetic materials in the vicinity of said borehole;
(e) taking earth samples at various known depths between the earth's surface and the approximate maximum depth of diagenetically-formed magnetic materials in a plurality of substantially vertical columns of earth laterally displaced from said borehole;
(f) measuring the greigite concentration in said earth samples;
(g) correlating the greigite concentration data of the samples from each of said substantially vertical columns to form a curve representative of relative greigite concentration as a function of depth for each of said plurality of substantially vertical columns;
and
(h) comparing the curves of relative greigite concentration as a function of depth for each of said plurality of substantially vertical columns to the curve of relative greigite concentration as a function of depth for said borehole.

6 more elements

Dependencies are inferred from the claim text.

Method of prospecting for hydrocarbon deposits

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Method of prospecting for hydrocarbon deposits

Life of this patent

Abstract

Claims37