US2374227A - Geochemical prospecting system - Google Patents

Description

April 24, 1945. I E, METCALF 2,374,227

TING SYSTEM 2 Sheets-Sheet 1 Filed June 17, 1940 fZisJ INVENTOR fie/255R 21'' ME 04 F W Cr? v ATTORNEYS.

' April 24, 1945. E ALF 2,374,227

GEOCHEMICAL PROSPECTING SYSTEM Filed June 17, 1940 2 Sheets-Sheet 2 s ANALYs/s PPA EATUS INVENTOR. HERBERT 1 METC'ALF BY k ATTORNEYS.

Patented Apr. 24, 1945 GEOCHEMICAL PROSPECTING SYSTEM Herbert E. Metcalf, San Francisco, Calif., as-

signor, by mesne assignments, to-Consolidated Engineering Corporation, Pasadena, Calif., corporation of California I Application'June 17, 1940, Serial No. 341,003

3 Claims.

My invention relates to a means and method for geochemical prospecting, and more particularly to a means and method of obtaining fluid .samples of undisturbed soil below the surface of the earth, together with analysis of the samples and correlation of the results to obtain data indicative of the presence or absence of deeper mineral deposits. My invention has its widest application in prospecting surface layers of the earth for gases which have migrated from deeper petroliferous deposits.

Among the objects of my invention are: to obtain fluid samples from below the surface of the earth without any substantial atmospheric contamination thereof; to provide a means and method ofobtaining substantially uncontaminated fluid samples from 'soil in situ; to provide a substantially uncontaminated soil fluid sample; to provide a gas and water sampling method which collects these fluids at a substantial depth beneath the earths surface from substantially undisturbed soil; to provide an apparatus for obtaining fluid samples from soil in situ beneath cases it is highly desirable the surface of the earth; to provide a means and method of trapping fluids from relatively undisturbed soil in a sample container; and to provide a simple and efficient means and method of obtaining fluid samples from soil beneath the surface of the earth. I

My invention possesses numerous other objects and features of advantage, some of which, together with the foregoing, will be set forth in the following description of specific apparatus embodying and utilizing my novelmethod. It

is therefore to be understood that my method is.

applicable to other apparatus, and that I do not limit myself, in any way, to /the apparatus of the present application, as I may adopt vari ous other apparatus embodiments, utilizing the method, within the scope of the appended claims.

In the copending application of Metcalf and Lawlor, Serial No. 341,004, filed June 1'7, 1940, entitled: Geochemical prospecting system, there was described and claimed a method and apparatus for aspirating liquid from soil in situ beneath the surface of the earth, and for directing this liquid into a sample container which is then sealedbefore being brought to the surface. In that application a means of supplying negative .pressure to the container was used in order that available liquids in the soil be aspirated therefrom and pass into the container. The preferred 'means outlined for that purpose was an exhaust pump situated on the surface of the ground and by which the container was inserted into the ground.

In utilizing the system as outlined just above, any gas which existed in the soil, as gas, would be exhausted to the surface by the pump and would therefore not be' present withinthe sample container. There are, of course, many types of prospecting where this loss of gas would in no way be significant, providing the analysis be confined wholly to the gas whichis entrained, dissolved or otherwise held by the aspirated liquid. It has been found, however, that in other to entrap .and seal as a sample both the soil gas and the liquid without any substantial'loss of either. Analysis is then made of the combined gas and liquid sample. I

Broadly, therefore, my present invention involves as to method, preexhaustion of a container, which is sealed to maintain the negative pressure therein, and which is then inserted in the ground to a predetermined depth, punctured to cause gas and liquid from the soil immediately surrounding the container to enter thereinto, and then rescaled in place to isolate from the atmosphere the fluids which have entered the container.

Preferably, as to apparatus, I prefer arod to be driven or otherwise progressed into the ground, the'end thereof carrying the exhausted container. Means are then provided to puncture the container so that the fluids may be drawn from the soil surrounding the container and rod into the container. Means are provided to reseal the container before withdrawal of the rod. I prefer to exclude atmospheric air from the container during the time that it is open so that practically its entire content is a fluid I sample fromsoil relatively undisturbed beneath the surface of the earth. As stated above, the

sample might comprise gas alone, gas and water,

or other liquid, or be almost wholly water in accordance with the water concentration at the location of taking the sample, which is preferples at uniform depthsbelow the water table.

ably below the water table although not necessarily so.

In this regard, while I prefer to take my samconnected with the container through 'the rod the area under investigation to establish a reference gradient. In any event, the sample obtained contains all the fluids that it is possible to force into the container by the difference of pressure between that in the original container and the surrounding soil. I prefer to leave the container open for asuiilcient time so that these pressures may become equalized.

In the drawings: r

Fig. 1 is a longitudinal, sectional view of a sampling rod having an exhausted container positioned therein, together with means for puncturing and rescaling the container.

Fig. 2 is a diagram showing the puncturing position of cover and container; and

Fig. 3 is a diagrammatic view showing the resealing of the container after aspiration has occurred. v

Fig. 4 is a plan view of the inner surface of the container cover showing the puncturing blade mounted thereon.

Fig. 5 is a diagrammatical view showing how the sampling rod is inserted into the earth.

Fig. 6 is a diagrammatic view of the manner in which the container is attached to a gas analy-.

sis apparatus.

Referring to the drawings for a more detailed description of my invention. a sampling rod body container is provided with a bottom I carrying thereon a fitting 9 provided with a threaded end I and diaphragm Ii, this fitting being used for attachment of the container to a gas analysis system, as shown in Fig. 6. Bottom 1 also carries an exhaust tube I2, one end being peripherally sealed to the bottom 'I and the other end having been connected to a vacuum pump for exhaust of the container, this exhaust tube being melted later to form a terminal vacuum seal asin electric lamp exhaust practice. Container 8 is also provided with a top I4, thistop being of standard tin plate material. The top also has a circular friction channel I therein, which is shaped to receive a circular friction ridge I6 on a can cover II when registered therewith and forced thereinto. Top and bottom I! and I 5, respectively, are attached to the side walls of container 6 with the usual roll seams I9, which are for prevention of leaks, preferably thereafter soldered- Thus, container 6 with its side .walls and top and bottom 'I and I5, respectively, is a vacuum tight receptacle which may be exhausted through exhaust tube I2 and thereafter sealed to preserve the vacuum therein.

,Iop roll seam l9 fits snugly against an inner shoulder formed in the interior of-cavity 5 and, I if desired, a. gasket may be used between roll seam I9 and shoulder 20' to prevent exhaustion of air from cavity 5. The pressure of seam is against shoulder 20 is Provided by screwing nose 2 on main body I, the container being fitted so that pressure of the threads 4 .will'f'orce the two toter blade 24,- which is bent down from cutter blade base attached to can cover I1. Cutter blade 24 is sharp and has diverging sides so that when forced against container top I4 the point of the cutter blade will punctuie and shear the top I4, as will be described later. Immediately above diaphragm 22 is an operating chamber 26 into which projects an axial operating plunger 21 extending to the upper end of the rod. Just before its emergence, plunger 21 is provided with threads 29 so that the plunger may be rotatedfrom above the surface of the ground and progressed downwardly, the wrench end 30 being protected by the ground.

Apertures 32 are provided connecting the ex- I inserted and the process repeated at another 10- 1 small as possible. Apertures 32 may be made small to exclude soil or may be filled'with a fluid pervious filter material.

In operation, the nose 2 of the rod is removed on threads 4, cover 22 positioned on backing plate 2|, and an exhausted sealed container placed in cavity 5. Pointed nose 2 is then replaced and screwed up tightly to force roll edge I9 against shoulder 20. The space between cover II and container top I4 is made to have a volume that is only a small fraction of the volume of the container, so that relatively small dilution of the sample occurs. Can cover 2| is automatically retained laterally in place by the side walls of the rod and rests between backing plate 22 and top I4 with the endof the cutter blade 24 in contact with the top of thecan. The rod is then progressed into the ground, either by driving or by rotation, until the container is at a desired predetermined depth. Plunger 21 is then rotated, the lower end thereof bearing against backing plate 2|, and as the plunger is rotated the backing plate pushes cover I! ahead of it. The cutter blade 24 is then forced against top H, punctures the top and shears through the top, as shown in Fig. 2, thus opening the container to the space between the cover and the top of the container. The negative pressure in the container 6 then draws or aspirates fluids, either gas or water or both, from the soil adjacent apertures 32 until the pressures are equalized and whatever has been aspirated is then in container 6. After the proper length of time has elapsed for the entrance of the fluids into container 6, operating plunger 30 is again rotated to force cover 2| tightly into engagement with top I4 of the container to give a friction seal of ridges I8 of the cover with channel I5 on the top of the container. The sample which was drawn into thecontainer is thus sealed and the rod may be withdrawn, pointed nose 2 unscrewed and the sealed container removed, labeled as to the location, depth, et cetera where the sample was taken, and set aside for analysis of the contents thereof. A newcontainer may then be cation. Obviously, marks may be used on wrench end 30 of the plunger to set the positions of the' plunger from the surface, corresponding to punctiming and rescaling positions of thecover.

In Fig. 6, I have shown the means by which the sealed and filled containers may be attached to agas analysis device. "Fitting 9 containing diaphragm is screwedto a system fitting H which is sealed to a vertical tube 42, the latter dividing at the top into a tube 43 going to a gas analysis apparatus under control of valve 44 and to a vacuum pump or similar device through tube driving cap 3| in case the rod is to be driven into 45 under control-of valve 48. Vertical tube 42 contains a sliding weight 41 having a pointed lower end 49 sharpened to puncture diaphragm II when dropped thereon. preferably of magnetic material and liftable to an upper position by surrounding it with solenoid iii; energizing the solenoid to attract weight 41, and lifting weight 41 by lifting the solenoid. In the upper position the solenoid may be deenergized to cause the weight to drop. The sharpened end 48 punctures the diaphragm and gas will then be admitted to tube 42. Prior, however, to the puncture of diaphragm ll, tube 42 is preferably pumped out by the action of the vacuum pump with valve 48 closed and valve 42 This weight 41 is opened. The gas analysis apparatus may then beheld at a reduced pressure so that gas from the sample contained in container 8 may be released into the gas apparatus under the influence of such treatment as may be necessary to release the gas therefrom. The gas released from the container may then be analyzed in known ways, for the presence of hydrocarbons such as, for example, the combustion method,

by the use of the Hertz diffusion apparatus, or by the use of a mass spectrometer as set forth in the copending application of Washburn & Taylor, Serial No. 320,802, flledFebruary 26, 1940.

The samples can be analyzed for any of the following: g

(a) Light hydrocarbons which have migrated or diffused from a petroleum deposit; I

(11) Chemicals derived from migratory constituents by catalytic action of the soil and other natural forces;

Any significant constituent the same path as the hydrocarbons;

(it) Any migratory constituent significant of underground mineral deposits.

After the analysis has been made, the results are noted and correlated with other results obtained to endeavor to outline, on the map record kept, patterns or gradients in terms of significant gas content, which will indicate the presence or absence of a subterranean deposit.

pending application of Lawlor and Metcalf, Berial No. 341,004, filed June 1'7, 1940.

1. In the art of geochemical prospecting wherein a plurality of earth content samples are systematically taken over an area to be pros- -pected, each sample enclosed in an individual container, and the samples subsequently analyzed for constituents which are related to gases which normally migrate upward from a mineral deposit below the sampling points, the improvement which comprises exhausting each container, placing such exhausted container at a substantial depth below the surface of the earth without substantial disturbance or aeration of said soil, and wherein such soil has not been previously disturbed at any substantially near cality, by means of a tool having provision for accommodatingthe container as well as means operable .from the earth's surface for breaking the seal and rescaling the container and adapted to be driven into the soil, the container while accommodated in said tool having communication with the exterior thereof, opening the exhaustedv container to aspirate fluid into said container from the soil surrounding said container only, rescaling said container and withdrawing the tool with the container to the surface whereby the contained sample together with that follows I It may be found that the extraneous gas in the space between the can top l4 and the diainert material, I prefer to close apertures 32 by an exterior slide which can be withdrawn to a position opening apertures 32 after the device has reached its proper sampling depth. Such a slide has been shown and described in the coothers of the said plurality may be analyzed to 'obtain data useful in locating said deposit.

2. The method of geochemical prospecting which comprises exhausting a container and sealing the same, placing such exhausted container at a substantial depth below the surface of 'the earth without substantial disturbance of the earth anywhere near the container, by a tool surface, to aspirate liquids and gases from the soil, then rescaling the container by operation of said tool, then removing the tool and container to a position above the surface, and then .removing said aspirated liquids and gases from the container. l

4 3.- The method of' geochemical prospecting which comprises driving into the earth to a sub stantial depth a tool carrying an exhausted and container, from the earth.

sealed container and having provision for opening and subsequently rescaling the container from the earths surface, without substantial disturbance of the surrounding earth, then oper-] ating the tool from the earth s surface to expose the interior of said container to aspirate and receive liquids and gases from the nearby earth, then operating the tool to seal the container again. and then removing the tool with the sealed HERBERT a. mom. 4,

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