US2475353A - Well surveying apparatus - Google Patents

Description

- July 5, 1949. HENRI-GEORGES DOLL WELL SURVEYING APPARATUS OriginaI Filed June 13, 1942 SOURCE OF ELECTRICAL ENERGY) (RECORDER.

BY I W/ 2 Shets-Sheet 1 FIG. 2.

iNVENTOR.

HENRI-GEORGES DOLL 7 7% HIS ATTORNEYS.

July 5, 1949.

Original Filed June 13, 1942 SOURCE OF EL\EC'TR/CAL ENERGY 3( REfORDER HENRI- GEORGES DOLL WELL SURVEYING APPARATUS 2 Sheets-Sheet 2 INVENTOR.

HENRI-GEORGES oou.

HIS ATTORNEYS.

Patcnted July 5, 1949 WELL SURVEYING APPARATUS Henri-Georges Doll, Houston, Tex, assignor to Schlumberger Well Surveying Corporation,

Houston, Tex., a corporation of Delaware Original application June 13, 1942, Serial No. 446,888. Divided and this application October 8, 1947, Serial No. 778,681

The present invention relates to apparatus for investigating earth formations traversed by a bore hole, and more particularly to new and improved apparatus for determining the depth and thickness of permeable formations traversed by a bore hole.

This application is a division of my copending application Serial No. 446,888, filed June 13, 1942, for Method and apparatus for investigating earth formations traversed by a bore hole, now Patent No. 2,433,746, granted December 30, 1947.

The above-mentioned copending application discloses methods and apparatuses for investigating earth formations traversed by a bore hole by means of alternating electro-filtration potentials. The latter potentials are created artificially by producing periodically fluctuating pressure in the bore hole liquid in the vicinity of permeable i'ormations, and they are picked up by electrodes connected to suitable indicating means.

The present application is addressed specifically to one form of apparatus in which mechanical means are employed for producing the periodically fluctuating pressure in the bore hole liquid.

The invention may be better understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

Figure 1 is a schematic diagram in longitudinal.

section of apparatus constructed according to the invention for producing alternating potentials related to electrofiltration potentials in a bore hole;

Figure 2 illustrates a curve of spontaneous potentials such as might be obtained by means of the apparatus shown in Figure 1;

Figure 3 is a schematic" showing of a modified form of the invention; and

Figure 4 shows the type of electrofiltration potential curve produced with the apparatus of Figure 3.

Referring now to Figure' l', the invention is shown embodied in apparatus'lll for producing periodic variations in the pressure of the liquid II at the level of a relatively permeable formation l3 traversed by a bore hole l2. It will be assumed in the following description that the pressure of the bore hole liquid l l is greater than the pressure of any fluid contained in the formation l3, so'that electrofiltration potentials will be present. The apparatus It comprises preferably a cylindrical water tight casing l4 containing an electric motor l5 which is adapted to drive, through conventional type gearing IS, a crank 3 Claims. (Cl. 175-182) arm ll on which is mounted a weight l8. The

22 in opposite directions.

crank arm I! is mounted in suitable bearin s l8 and 20 for rotation about a vertical axis.

The crank arm ll drives, through conventional gearing 2|, a second crank arm 22, journalled in suitable bearings 23 and 24 for vertical rotation within the casing l4 and having a weight 25 mounted thereon. It will be noted that the gearing 2| causes the crank arms I! and 22 to rotate in opposite directions, when the motor I5 is in operation.

One terminal ofthe motor I5 is connected to a conductor 26 in the supporting cable 21, the upper end of which is connected in series with a conventional type switch 28 and a suitable source of electrical energy 29, the other terminal of which is connected to ground at the point 30 at the surface of the earth. The energizing circuit for the motor I5 is completed through the earth and the bore hole liquid II and to this end its other terminal is grounded to the body of the apparatus H at the point 3|. If any interference is encountered between the current and the recording circuits, it may be desirable to use a second conductor in the cable 21 instead of the ground return.

In operation, the switch 28 at the surface of the earth is closed and the apparatus In is moved through the bore hole I2. This energizes the motor i'5, causing it to drive the crank arms l1 and The result of this rotation of the weights I8 and 25, respectively, on the crank arms I! and 22, respectively, is to impart an extremely vigorous vibrating motion to the apparatus ill in a plane perpendicular to the paper. This vigorous vibration produces periodic increases and decreases in the pressure of the 14, preferably on a radius perpendicular to a line passing through the centers of the bearings l9 and 23. The electrode 32 may be connected through a conductor 33 in the supporting cable 21 to one terminal of a conventional alternating current potential indicating instrument 34, prefaemass erably of the. recording type, the other terminal of which may be connected to a ground point II at the surface of the earth.

A representative curve such as might be obtained by the recording apparatus 84 is shown in Figure 2, from which it appears that the spontaneous potential curve is modulated in the vicinity of the porous formation It at the frequency of vibration of the apparatus ID in the bore hole. The normal spontaneous potential curve, such as might be obtained with the switch 2. open, is shown in dotted lines for purposes of comparison.

In the embodiment described above, other measuring circuits may be employed for obtaining indications of electrofiltration potentials in a bore hole. For example, in Figure 1, indications of electroflltration potentials might be obtained by making measurements between the electrode 32 and another electrode 80 located at the same level on the other side of the casing ll opposite the electrode 82 and connected by a.conductor II to the recorder 34, as in Fig. 3. This modification produces a curve of alternating electrofiltration potentials alone (Fig. 4). As a further modification, indications might be obtained of the voltages between each of two such electrodes and ground. 1

The invention thus provides a new apparatus for obtaining indications of electrofiltration potentials apart from other continuous potentials that may be present in a bore hole. By producing a localized and periodically variable pressure variation at different depths in the bore hole, continuous electrofiltration potentials may be changed to alternating potentials that can be readily separated from other continuous potentials which may be encountered. Accordingly, the invention enables accurate indications of electroflltration potentials to be obtained with-- out taking any special precautions even in wells located in the vicinity of relatively strong telluric currents.

The embodiment described above is intended to be illustrative and not restrictive. Numerous modifications in form and detail may be made in that embodiment within the scope of the following claims.

I claim:

1. In bore hole investigating apparatus, the combination of a body adapted to be lowered into a bore hole containing a liquid, an eccentric mass rotatably mounted in the body, power means for rotating said mass to produce periodic pressure fluctuations in said liquid at a relatively rapid rate above that to which a direct current meter is responsive, thereby generating variable altemating electroflltratlon potentials in the vicinity of permeable formations, a first electrode assembled to said body so as to be movable at substantially the same level therewith, a second electrode located at a position where it is not subject to the same instantaneous pressure as said first electrode, circuit means transmitting to the surface alternating potentials picked up by said electrodes and produced by said generated alternating electroflltration potentials, and means for providing indications of said alternating potentials.

2. In bore hole investigating apparatus, the combination of a body adapted to be lowered into a bore hole containing a liquid, a pair of eccentric masses rotatably mounted in the body, electrical power means for rotating said masses to produce periodic pressure fluctuations in said liquid at a relatively rapid rate above that to which a direct current meter is responsive, thereby generating variable alternating electroflltration potentials in the vicinity of permeable formations, a source of electrical energy at the surface, electrical means for energizing said electrical power means from said source, a first electrode assembled to said body so as to be movable at substantially the same level therewith, a. second electrode located at a position where it is not subject to the same instantaneous pressure as said first electrode, circuit means transmitting to the surface alternating potentials picked up by said electrodes and produced by said generated alternating electrofiltration potentials, and means for providing indications of said alternating potentials.

3. In bore hole investigating apparatus, the combination of a body adapted to be lowered into a bore hole containing a liquid, an eccentric mass rotatably mounted in the body, power means for rotating said mass to produce periodic pressure fluctuations in said liquid at a relatively rapid rate above that to which a direct current meter is responsive, thereby generating variable alternating electroilltration potentials in the vicinity of permeable formations, a first electrode assembled to said body so as to be movable at substantially the same level therewith, a second electrode located at substantially the same level as said first electrode and on the opposite side of the body therefrom, said first and second electrodes being so positioned that they are not subjected to the same instantaneous fluid pressure, circuit means transmitting to the surface alternatin potentials picked up by said electrodes and produced by said generated alternating electrofiltration potentials, and means for providing indications of said alternating potentials. I

HENRI-GEORGES DOLL.

No references cited.

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