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Патент USA US2406611

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Aug. 27, 1946.
H. 'r. KENNEDY
2,406,61 1
GEOCHBIICAL PHOSPEGTING METHOD
Fllod July 3. 1940
2 Shanta-Shut 2
2,406,611
Patented Aug. .27, 1946
uuirrao srA'rss PATENT OFFICE
0
‘ Gulf Research a Development 0cm
burgh. 2a., a corporation of Delaware
Application July 3, ‘19M, Serial No. 348.804
2 Claims. (01. 23-230)
.
‘
1
,
,ured concentrations bear a far closer relation to
the true distribution of the hydrocarbons in the
earth, and to the oil and gas deposits from which
This invention or discovery relates to geochem
icai prospecting methods; and it comprises a
‘method of prospecting for gas and oil deposits
including the steps of taking samples of ground
the hydrocarbons di?use, than in any of the pre
vious expedients. Among other things, errors
due to variations in adsorptivity of soils are obvi
water in the earth at various spaced points at
~ levels adjacent the water table and quantitatively
ated.
Ground water is meteoric water (rainfall, melt
determining the concentration of petroleum hy
drocarbons in the samples; the method being
also applicable to other deposits giving rise to
water soluble vapors or gases; all as more fully
hereinafter set forth and as claimed.
ing snow, etc.) which has percolated downward
10
into the pores and ?ssures oi’ the superficial por
tion of the earth. Ground water saturates the
earth from an upper level, known as the water
Oil and gas prospecting methods have been
table, downward as far as free percolation is
devised involving detection and quantitative
possible. It is distinguished from water or brines
measurement of traces of oil and gas hydrocar
with, and of age corresponding to. the
bons in the earth at various points over a region, 15 associated
deeper sedimentary rocks. Ground waters are
with the immediate object of locating and de
‘ordinarily fresh, that is free of dissolved salines,
ilning regions of high gas concentration and the
while connate waters are often brines. Ground
ultimate object of locating subterranean oil-and
water moves in slow currents through the earth.
gas reservoirs. Such geochemical prospecting
methods are attractive because they are more 20 under the in?uence of gravity, and makes its
appearance at springs and at water wells.
direct than the usual geophysical prospecting
It is this ground water; as distinguished from
methods which at best can only reveal favorable
connate
waters. that is sampled and analyzed for
geological structures which may or may not con
petroleum‘hydrccarbons
according to the inven
tain oil and gas.
The earliest geochemical methods involved tak 25‘ tion. The ground water has in general not come
into contact with oil or gas pay formations; it is
utilized in the present invention merely as an
the surface or at depth. However such proce
absorbent
or reservoir for seep gases which have
dures often give very erratic results. In taking a
come from such. formations.
sample of gas by suction through a pipe more
In carrying out the invention, test wells to the
or less air is drawn in from the surrounding earth. 30 water
table are dug at various points over a re
and the amount of dilution from this source de
gion under investigation, if water wells are not
pends on the permeability and other characteris
already available. and water samples are taken
tics of the surrounding earth. By the same token
under conditions preservative of the gas content
such a gas sample is not fairly representative
thereof. Gas concentrations are measured and
of a small de?nite zone but may include gas 35 plotted
on a map of the region to show gas “highs”
from other levels or leaking in through crevices
and
"lows.”
It is desirable to know the direction
from quite distant points.
of movement of the ground waters, as an aid to
Some improvement is had by taking samples of
tracing structure. This can be determined by
the soil or rock itself, and extracting gas there
from for analysis. Porous soil entrains gas and 40 suitable methods or can be inferred from local
geological data.
also acts as an adsorbent for gas in a manner
It is known that leakage or diffusion of the
somewhat like activated charcoal. But here the
more volatile petroleum hydrocarbons through
concentrations formed depend on the porosity and
the crust of the earth takes place at all times
adsorptivity of the soil, which may vary widely
although the amount of such transfer may be
45
from place to place. and on other factors.
exceedingly minute. In some localities, vertical
In all these. methods the concentrations of oil
.diilusion may be of suilicient magnitude so that
and gas hydrocarbons (mostly methane and
high values may be obtained continuously over
ethane) are extremely small; of the order of a
a, reservoir. More frequently, however, high con
few parts per million at most and often only a
50 centrations are found near faults that intersect
few parts per billion.
,
the pay sand, and on the lower side of these
The present invention is based on the discov
ing samples of gas directly from the soil near ‘
ery that by taking samples of ground waters at
various points over a region to be investigated,
and determining the (minute) concentrations
of oil and gas hydrocarbons therein, the meas
faults, along the path of ?ow of the ground
water.
when the direction of ?ow of ground water
is known it is frequently possible to trace the
9,408,61 1
source of the emanation, which may be a fault,
a Joint. or other channel through which the
emanation may reach the surface, especially by
concentrate in the upper vapor space of the con
denser and are drawn slowly over through the
water trap 20 which is maintained at about —80°
making a series of tests in the general direction
C. by a bath or dry ice in a Dewar container 21
of movement of the ground water. Since the
it. v'I‘he gases are then drawn
complete characteristics of faults are frequently a surrounding
through a drier tube 20 where the last traces of y
known or determinable by surface or geophysical
moisture are removed by passage over phosphoric
measurements, it is often possible to determine
anhydride, and thence pass through a tube II
with considerable accuracy the ultimate source
?lled with caustic soda, where carbon dioxide
of the emanation.
.
10 and other acid gases are removed. A Toepler
The water samples taken as described are freed
pump 30 of conventional form draws the gases
of gas by heating and the gas is analyzed by any
suitable method capable of the required high
sensitivity. Suitable spectrographic and micro
through the preceding puri?cation train and de
livers them to a reservoir Ii from which they
?ow at a slow and uniform rate through an ac
combustion methods are available. but at pres 15
tivated-charcoal tube 32 immersed in a dry ice
ent I regard a fractional evaporation method
bath maintained at a temperature oi about -80°
described in detail below as the most conven
C. The reservoir II is adapted to accumulate
ient.
gases removed from the water in the early stages
In the accompanying drawings, there are shown
diagrammatically an illustration of field prac 20 of the pumping when gas is being pumped at a
rapid rate and to deliver these gases slowly and
tice of the invention and a diagram of one suit
uniformly through the charcoal tube 82. Reser
able apparatus organization for analysis.
voir I8 is a level bottle which can be moved vere
In the drawings:
tically to receive and withdraw mercury from
Fig. 1 is a schematic view in central vertical
section through the earth, illustrating the rela 25 reservoir II when the pinch clamp is open. Dur
ing the process of passage of gas through the
tion of ground water gas concentrations to struc
charcoal tube 32 the hydrocarbons are adsorbed
ture in a typical case.
on the activated charcoal and the residual gas
Fig. 2 is a diagrammatic showing of one good
consisting mainly of oxygen, nitrogen. and some
apparatus organization suitable for use in the
times methane. pass through the charcoal and
invention. and
Fig. 3 is a chart showing how ethane concen 30 are vented to the atmosphere by means of the
two-way cock ll. It has been found that the re
trations are determined.
moval of 5 or 10 per cent of the water in the still
Referring to Fig. 1, a section of the earth
28 to the trap 20 insures the complete removal
I about four miles long is shown schematically,
with a buried fault 6 of which there is no visible 35 of ethane from the water sample, provided the
water is boiling vigorously with ample reflux in
indication at the surface of the earth. The water
the condenser 20. When this amount of water
table is indicated at ‘I. Below this surface the
has been collected in the trap 28 the stopcock
earth is saturated with water, ?owing in the ‘di
35 is closed and the tubes I0, 28 and 20 are ex
rection shown. G'as seeps up through the fault
as shown by arrows. The situation diagrammed 40 hausted to a pressure of a fraction of a millimeter
of mercury by continued action of the Toepler
is typical of the Gulf Coast. Water samples are
pump 30 transferring substantially all of the
taken at wells 0. 8, l0 and II and at point l2
dried and purified vapors removed from the water
where the water table almost intersects the sur
sample to the charcoal tube 32. When all the
face of the earth. Samples are generally not
gases have been passed through the charcoal
taken in open bodies of water, as these are sub
ject to atmospheric actions and moreover may 45 tube, excess air in the charcoal and in the ap
paratus to the right of this tube are exhausted
be contaminated with marsh gas of vegetable
by turning the cock ll so as to lead to a mercury
origin. The samples, substantially free of soil,
pump (not shown in the diagram) the cock I!
are quantitatively analyzed for ethane or other
being closed and the mercury cut-o?s 80 and
petroleum hydrocarbon, and the concentration
values (usually a few parts in ten million) are 50 39 being lowered. When the pressure in the sys
tem I2, 80, I0 and 40 reaches about 0.002 mm.
plotted to scale. The abrupt rise in ethane con
mercury as measured by the McLeod gauge ll
centration at l3, considered in relation to the
about three grams of mercury are admitted into
direction of ground water movement. gives an in
the charcoal tube 32 from the reservoir 3| by
dication of the fault.
Referring to Fig. 2, illustrative of the analysis 55 raising the reservoir 33 and heat is applied to the
charcoal tube 32 to vaporize the mercury, remov
organization, 20 is a sample tube which may be
ing adsorbed gases from the charcoal and carry
?lled with ground water by pumping the water
ing these gases into the vapor trap 40 where
through the tube, or by lowering the tube into
ethane and less volatile vapors are condensed,
the well, or by any other suitable means. In
some cases it is desirable to employ special sample co the mercury in the meantime being condensed
in the cut-oil’ 8B and residual air and other vol
containers which may be sealed while in the
atile gas are pumped off. When the mercury
well, thus preventing any loss of emanation. A
distillation is complete the adsorbed gases are
convenient sample size is a liter or thereabouts.
entirely removed from the charcoal, this being
The method of examining water samples will be
explained with particular reference to the deter 65 done at a temperature of about 150° C. The mer
cury level in the cut-off 80 is then raised, the cock
mination of ethane, since this constituent seems
31 opened to the mercury pump again until the
to be the most reliable indicator for petroleum.
pressure in the system 40, 4| and 88 is lowered
To accomplish the analysis for ethane in ground
water the sample of ground water in the con
to about 0.002 mm.
The temperature or the
70 vapor trap 40 is then slowly raised by allowing
the bath surrounding it to warm up, the tem
cock 2! in the neck of the still 20. The water
perature being conveniently measured by a triple
sample in the still is heated by heater 2‘ and the
iunction thermocouple attached to gpotentiom
water is boiled and recondensed by the condenser
eter circuit (not shown) and the pressure
II. Gases which were dissolved in the water thus
75 measured by the McLeod gauge ll. Both tem
tainer 20 is displaced by mercury up to the stop
2,406,811
5
perature and pressure are measured at frequent
intervals as shown in Figure 3.
The data obtained are plotted as shown in Fig
ure 3 and the pressure rise DP between the two
breaks is measured. The volume 01' ethane in
milliliters at atmospheric pressure originally
present in the water sample is then determined
by multiplying the pressure rise in atmospheres
by the volume in milliliters of the apparatus from
' comprises taking samples of ground water in the
earth at a plurality of spaced points in the region,
at levels adjacent the water table, said ground
water samples being free from signi?cant quan
titles of soil, con?ning the samples from access
to air before substantial diminution of ethane
concentration therein, and thereafter quantita
tively determining traces of ethane dissolved in
the samples as indicative of the presence oi’ oil or
the top of the mercury on the right side of the 10 gas.
2. A method of exploring for relatively deep
mercury cut-oi! I. to the top of the mercury on
the left side of the cut-oi! 39, including the Mo
Leod gauge. By this method, ethane in amounts
petroleum deposits which comprises taking a
ground water sample substantially free of soil
particles from each or a plurality of spaced points
as small as 0.0001 milliliter may be detected, and
larger amounts may be measured with a fair de 15 located near the water table in the zone of ex
ploration. promptly con?ning each sample from
gree of accuracy. Other emanations such as
methane, propane may be similarly determined,
but for reasons already given. ethane is preferred
as an indicator of petroleum.
What I claim is:
1. A method of prospecting a region of the
earth for subterranean gas and oil deposits which
contact with extraneous ?uids and
tly
analyzing the samples for dissolved gaseous con
stituents derivable from petroleum, as indicative
of the presence of relatively deep hydrocarbon
deposits.
HARVEY '1'. 1w
1"
Certi?cate of Correction
August 27, 1946.
HARVEY T. KENNEDY
It is hereby certi?ed that error appears in the rinted speci?cation of the above
olumn 4, line 58, strike out the
Patent No. 2,406,6 1 1.
num ered patent requiring correction as follows:
such that; and that the
"where” and insert instead cooled to a_ low temperature
_
said Letters Patent should be read with this correction therein that the same may
conform to the record of the case in the Patent Oi?ce.
Signed and sealed this 15th day of October, A. D. 1946.
[Ian-1
LESLIE FRAZER,
First Am'atmzt Uommiasioner of Patents.
2,406,811
5
perature and pressure are measured at frequent
intervals as shown in Figure 3.
The data obtained are plotted as shown in Fig
ure 3 and the pressure rise DP between the two
breaks is measured. The volume 01' ethane in
milliliters at atmospheric pressure originally
present in the water sample is then determined
by multiplying the pressure rise in atmospheres
by the volume in milliliters of the apparatus from
' comprises taking samples of ground water in the
earth at a plurality of spaced points in the region,
at levels adjacent the water table, said ground
water samples being free from signi?cant quan
titles of soil, con?ning the samples from access
to air before substantial diminution of ethane
concentration therein, and thereafter quantita
tively determining traces of ethane dissolved in
the samples as indicative of the presence oi’ oil or
the top of the mercury on the right side of the 10 gas.
2. A method of exploring for relatively deep
mercury cut-oi! I. to the top of the mercury on
the left side of the cut-oi! 39, including the Mo
Leod gauge. By this method, ethane in amounts
petroleum deposits which comprises taking a
ground water sample substantially free of soil
particles from each or a plurality of spaced points
as small as 0.0001 milliliter may be detected, and
larger amounts may be measured with a fair de 15 located near the water table in the zone of ex
ploration. promptly con?ning each sample from
gree of accuracy. Other emanations such as
methane, propane may be similarly determined,
but for reasons already given. ethane is preferred
as an indicator of petroleum.
What I claim is:
1. A method of prospecting a region of the
earth for subterranean gas and oil deposits which
contact with extraneous ?uids and
tly
analyzing the samples for dissolved gaseous con
stituents derivable from petroleum, as indicative
of the presence of relatively deep hydrocarbon
deposits.
HARVEY '1'. 1w
1"
Certi?cate of Correction
August 27, 1946.
HARVEY T. KENNEDY
It is hereby certi?ed that error appears in the rinted speci?cation of the above
olumn 4, line 58, strike out the
Patent No. 2,406,6 1 1.
num ered patent requiring correction as follows:
such that; and that the
"where” and insert instead cooled to a_ low temperature
_
said Letters Patent should be read with this correction therein that the same may
conform to the record of the case in the Patent Oi?ce.
Signed and sealed this 15th day of October, A. D. 1946.
[Ian-1
LESLIE FRAZER,
First Am'atmzt Uommiasioner of Patents.
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