April 16,1935.
`
`H; R. PRESCOTT
`, 1,998,412
`METHODVOF MAKING GEOLOGICAL EXPLORATIONS
`
`' Fil'ed March 29, 1954
`
`2 Sheets-Sheet 1.
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`1/50
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`5249. a.
`
`INVENTOR
`hbm/a'E/Drcscofz‘
`
`BY
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`1
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`'
`
`_ ATTORNEY
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`PGS Exhibit 1012
`PGS v. WG
`
`

`

`j -April 16, 1935.-
`
`-
`
`H. R. PRESCOTT
`
`'
`
`1,993,412
`
`METHOD OF MAKING GEOLOGICAL EXPLORATIONS
`
`’
`
`Filed March 29, 1934
`
`' 2 Sheets-Shéet 2
`
`77ME
`
`ATTOR I Y
`
`PGS Exhibit 1012
`PGS v. WG
`
`

`

`Patented Apr. 16, 1935
`
`1,998,412
`
`UNITED STATES.
`
`PATENT: OFFICE‘ ~
`
`> 1,998,412
`
`METHOD OF MAKING ' GEOLOGICAL
`
`>
`
`I
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`EXPLORATIONS
`
`(Cl. 181-05) _
`.
`Figure 2 is a diagrammatic view showing the
`waves generated by the several charges in Fig. 1
`as would‘be received by a seisphone positioned at ‘
`
`pointQinFig. 1.v
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`‘Fig. 3 is the resultant curve of the sine curves in
`Fig. 2 showing the resultant of the impulses which
`would be received by a seisphone at point Q in
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`Harold It. Prescott, Ponca City, Okla., assignor to
`Continental Oil Company, Ponca City, Okla.)
`corporation of Delaware;
`Application March 29.
`‘1934, Serial No. 711,932
`4 Claims.
`My invention relates to a method ‘of making -
`geological explorations, and more particularly to
`a method whereby geological explorations are
`carried out by generating vibrations in the earth’s
`5 surface in such a manner as to eliminate many
`undesirable vibrations near the origin thereof,
`and particularly in the vicinity of the earth’s sur
`- face.
`
`Fig. 1.
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`Fig. 4 is a diagrammatic view showing wave mo- _
`One method of making geological'explorations
`tions of longer wave lengths than those shown‘in
`consists in generating earth vibrations by deto
`nating an explosive at or. near the earth’s surface.
`Fig. 2.
`'
`wave motions
`Fig. 5 is the resultant curve of the
`Vibrations or wave trains of motion are set up in
`the surface of the earth passing in all directions
`in Fig. 4.
`‘
`Fig. 6 is a curve showing the wave motion which
`from the center of the disturbance. Part of the
`would occur if the amount of explosive detonated
`vibrations travels into the earth; another portion
`in accordance'with the method of my invention
`of the vibrations is re?ected'or refracted when
`were exploded according to the practice of the
`ever vibrations pass from one medium into an- '
`prior art.
`other medium having diiferent' physical charac
`- In general, my invention provides a method of ,
`teristics. The re?ected or echoed portion of the
`generating earth vibrations in which 'the' total
`20 "
`vibrations travels back to the surface of the earth
`amount of .explosive is ‘divided up into a plurality
`where suitable seisphones are stationed which are
`of independent parts suitable spaced from each
`adapted to translate the vibrations ‘into record
`other. The‘uppermost portion of the explosive is
`able vibrations by electrical or combined electrical '
`?rst detonated and the succeeding portions vare
`and photographic means.
`detonated in succession in a progressive manner. '7
`A large part of ‘the vibrations caused by the‘
`The arrangement is such, as will be‘ more fully
`explosion passes‘ directly to the surface layer of
`explained hereinafter,‘ that a large part of the
`.the earth and causes vibrations of large amplitude
`vibrations is eliminated, at the surface of the
`near the origin of the' blast for appreciable pe
`earth, while that portion of the earth below the
`riods of time. These vibrations are troublesome.
`line of explosive units receives a large impact
`30
`Because of their amplitude they tend to camou- Y
`fully the equivalent of that which it would have I
`?age or mask the re?ected or echoed vibrations '
`‘received. if the total amount of explosive were
`from- the various tectonic formationsvand sub
`detonated simultaneously. In this manner the re
`surface strata, - In many localities because of the
`?ected or echoed vibrations can be received‘ and
`physical character of the surface layers satisfac
`recorded. at the surface of the earth by suitable
`tory exploration of the deep lying geological
`means without the camou?aging or masking ef
`strata cannot be carried out by means of earth
`feet which is~had by the methods of the prior art. "
`vibrations.
`,
`Referring now to the drawings, in the earth’s
`One object of my invention is to provide a
`method of making ‘geological explorations by
`surface 50 is'bored a hole 5| having 'a depth D, as '
`indicatedin Fig. 1. Within the hole 5| are placed
`means of generating earth vibrations in which
`a number of explosive charges ,I, 2, 3, 4, 5, 6, ‘I, 8,
`trailer waves in the near surfacelayers are min
`9 and Ill. The charges may be placed at varying ,
`distances from each other.
`Another object of my invention‘is to provide
`‘Usually _ the inter- " '
`charge distance is equal. The only limitation
`a method of geological exploration in which the
`.with respect to the distances the charges are to
`total impact in the near surface layers is reduced
`45
`be spaced from each other is that no charge shall
`_ While permitting a maximum amount of energy
`be at a greater distance from its adjacent charge 9
`to be delivered tothe deeper geological strata.
`' than that at which the effect of sympathetic deto-,
`Further and other objects of my invention will
`nation is effective, that is to say, the space be
`appear from the following description.
`tween two adjacent charges shall not be greater
`In the accompanying. drawings which form part
`than the distance at which the detonation of an
`of the instant speci?catiomand which are to be
`adjacent, explosive unit will yield su?icient shock
`read in conjunction therewith,
`_
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`to detonate an adjacent unit after the elastic .
`Fig. 1 is a diagrammatic view of a section
`wave given by a unit travels to its adjacent-unit.
`through the earth’s surface showing the paths of
`The reason for this will be apparent from the
`a number of vibrations at a given instant.
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`PGS Exhibit 1012
`PGS v. WG
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`. 2
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`ZOllB
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`it. at:
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`1,998,412 '
`‘the time duration of V2 wave length is equal to or
`mode of operation, which is as follows. when
`less than the time elapsing from the first impact
`the uppermost charge I is detonated the vibration
`of the explosive string to the last impact of the
`wave or explosive impact will travel out from
`charge I' in all directions. As this impact ‘strikes
`explosive string.
`'
`By refen'ing to Fig. 6 in which the same amount >
`charge 2, ‘it will» cause charge .2 to detonate and
`of explosive was-used asthat in obtaining the
`the detonation of charge 2 will travel out in all
`curves in Fig. 4, except detonated simultaneously,
`directions.‘ That part of the second impact which
`it will be observed that'the amplitude Gt of the
`' travels directly downward will add to the ?rst im
`trailer waves is substantially equal _to the ampli
`pact from unit I and the combined resulting im
`pact travels-downwardly to detonate unit 3. The
`tude d1 of the ?rst impact. Also it is to be‘ observed
`10
`that the or of the ?rst impact of Fig. 5 employing .
`action progresses downwardly from one explosive
`the principle of progressive detonation is de?nitely
`unit to the ‘next until all of the units are detonated.
`less than the ?rst impact (11 of Fig. 6 in which
`By referring to Fig. 1, it will be' observed that
`there is shown on‘ the ?gure a plurality of curves
`simultaneous detonation was used as in the prior .
`art. This is-also very important in reducing un
`l', 2', 3', 4', 5', 6', 'l', 8', 9', and I0’. These curves
`desirable surface vibration.
`represent the paths of the impacts at a given
`In the drawings-the showing is theoretical in v
`instant. It is to be remembered, of course that
`the wave-front travels substantially along the
`that it is assumed the wave fronts will travel in -
`perfect spheres and that the resistance to travel
`surface of a sphere. Inasmuch as Fig. 1 is a sec
`is small. In actual practice the resistance to
`20
`tional view, the curves I’, 2', etc., appear as por
`travel, .of course, naturally reduces the ampli-'
`tions of acircle. It will also be observed that
`tude of the trailer waves. The instant showing,
`there is a point P at which all of the impacts
`however, will clearly illustrate the principle.
`are united, so that the result is equivalent of a
`Referring again to Fig. ,1 it will be observed
`'single largeimpact passing downwardly to the
`that a number of 30° zones have been drawn; the
`geological strata below. At another point, as for
`25
`zones of 30° on each side of the hole being labeled
`example Q, it will also be observed that all of
`zone I; the next zones being zones 2, and the next
`the impacts from the separate explosive units.
`zones beingzones 3, etc. 'Ihe‘two zones directly
`will arrive at different times. The wave motion
`beneath the hole and comprising an arc of 60“
`at Q from explosive unit I is represented in Fig. 2
`are designated'as zone 6. It will be obvious that
`by curve l". The wave motion at point Q from
`in. zone 6 there will be very little elimination of
`explosive unit 2 is represented in Fig. ,2 being
`trailer waves. This is what I desire inasmuch as .
`curve 2". Similarly the wave motions of respec
`I seek to get a maximum impact traveling down
`tive explosive units 3, 5, 5, 5, l, 8, g and ill at
`point Q are represented in Fig. 2 by curves 3", 5'1’,
`wardly.
`'
`In the following table Fe represents the fre¢
`5f!’ 6!!’ 'lllxsll, s!) and let!- I
`quency above which elimination of trailer waves
`Fig 3 shows the resulting vibration at point
`is fully effective. ' Fp represents the frequency
`of the separate vibrations given out by the sev
`above which elimination of trailer waves is par-.
`eral explosions. It will be observed that the
`tially e?ective. The term tp represents the elapsed
`resulting vibration consists of a single impact
`time of progressive ?ring from the ?rst to the last
`with no trailer wave motions following, the trailer
`ShOt:
`j.
`wave motions having been neutralized by "inter
`' ference. It will be further obvious by reference to
`Figs. 2 andv 3 that the troublesome trailer vibra
`tions
`be substantially eliminated by my meth- .
`0d of' progressive ?ring forall those frequencies
`of which the time duration'of one wave length
`‘ is equal to or less than the time interval for the
`~passing of the impacts from explosive units l to
`it. For example, if the elapsed time at the point
`‘Q from the ?rst impact to the last impact were .1
`second then the frequency having a wave length
`equal to .1 second, that is a wave motion of 10
`cycles per second, and all frequencies higher
`would have substantial elimination of trailer wave
`motions in the manner shown by Fig. 3.
`.»
`Referring nowto Fig. 4, I have taken, for pur
`pose of illustration only, 7 explosive charges.
`The number of explosive charges is not critical as
`long as there are su?icient to give the desired
`smooth curve. In Fig. 4 it will be observed that
`the time elapsing from the ?rst charge to the last
`charge is less than the ‘wave length of the wave
`motions. By way of example, I have taken an
`elapsed timeof ?ring which is .‘7 of the time of
`duration of one wave length. The resultant curve
`of the wave motions in Fig. 4 appearsdn Fig.5.
`vIt will be observed that the amplitude or of the
`?rst impact-is larger than the at of the trailer
`wave. It will be apparent that though the trailer
`waves have been reduced in amplitude they have
`not been fully eliminated. For practical purposes
`any reduction in the amplitude of the trailer
`waves is of’ benefit. It will be also apparent from
`the foregoing that there is a partial elimination of
`the trailer waves for all those frequencies of which
`
`' Wh?e'I have Pointed. out above that I prefer
`to space the'explosive units at distances no great
`er than that at which sympathetic detonation may _
`be effected, my method could be used equally well
`with explosives which would not detonate pro
`'gresslvely, or with the explosive charges placed
`at greater distances than those at which sympa
`thetic detonation would take place. This could
`be done by placing electric blasting caps in each
`unit and connecting the respective lead wires to
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`In an actual shot in which the depth of the
`hole was 100 feet and the time is required for the
`progressive detonation of the explosive units l to
`It was .025 second, the following table will illus
`trate the various frequencies showing the limita
`tion of fully effective elimination and partially
`e?ective “elimination in the various zones.
`quencies are given in cycles per second:
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`55
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`Fre- 1
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`CID-“Mid
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`Eases
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`Eases
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`60
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`70
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`PGS Exhibit 1012
`PGS v. WG
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`and described.
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`2. In a method of making geophysical explcrae
`a suitable electric tiring device which would space
`domain which an explosive is employed-to create.
`the intervals of detonation according to the needs
`of the geological locus being explored.
`‘ earth vibrations, and re?ections of said vibra
`In actualpractice I have been able to conduct
`tions are received at or near the earth's surface, -
`geological explorations in terrains where ordi
`detonating a vertical series of spaced explosive
`charges in succession ‘from the top downwardly,
`nary methods would have been useless, namely. at Y
`whereby trailer wave from the detonating
`_ a point having sand and river ?ll on the surface. '
`charges is reduced in‘amplitude when received
`It will be understood that I have accomplished
`.the objects of my; invention. I am enabled to
`at or‘ near the earth's surface.
`‘conduct. geological explorations and ‘eliminate
`3. In the art of creating earth vibrations for
`geological explorations, detonating a series of
`troublesome trailer vibrations at or near the
`vertically spaced explosive charges in succession
`earth’s surface, and to‘ reduce‘ the amplitude of
`the primary impacts at or near the earth's sur
`for a time interval of at least that of the time
`face. In: this manner I am able to obtain accu
`of duration of one-halfcycle of a wave motion
`of thedesired frequency, whereby the amplitude‘
`rate records which are not camou?aged by trou
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`blesome trailer vibrations. By tuning the receiv-'
`of the trailer wave of the impact from the sevf
`ing instruments to those frequencieswhose trailer
`eral detonations is reduced when received at or -
`waves are eliminated, I vam enabled to obtain'an
`near the earth's surface.
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`‘unusually \clear record from which satisfactory f
`4. A method of making geophysical explora
`tantially vertically position-i 20
`results may be obtained
`tions including s
`It will be understood that certain features and
`ing a plurality
`charges of explosives spaced
`sub-combinations are of utility and may be em‘
`from-each other at intervals su?iciently close so
`ployed without reference to other features and
`that the explosion of a charge will detonate an
`sub-combinations. This is contemplated by and
`adjacent charge by sympathy, detonating the
`is within the scope of my’ claims. Itis further
`uppermost charge,~ permitting the remaining
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`- ‘obvious that various changes may be made in de
`charges to'be sympathetically detonated in suc
`tails within the scope of my claims without'de
`cession,_and employing a su?icient number of
`parting from the spirit of my invention. It is, ’
`charges so ‘that successive explosions will occur
`therefore, to be understood ‘that my invention is
`during an interval of at least the’ time of dura
`not to be limited to the specific details shown
`- tion of one-half cycle of a wave motion of the
`desired frequency, whereby the‘ amplitude of the
`Having thus described my invention, what I
`trailer wave of the impact of the resultant of
`the several detonation's is reduced when received
`at or near the earth's surface.
`~
`Kanpur R. Panacea-1'.
`
`claim is:
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`i
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`1. A method of making. geophysical explora-v
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`tions including the step of exploding a substan
`tially vertlcal series of spaced explosive charges
`
`in
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`PGS Exhibit 1012
`PGS v. WG
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