US2352834A - Method of and means for adjusting flow rates of fluids through formations traversed by boreholes - Google Patents

Description

July 4, 1944. G, HASSLER 2,352,834

METHOD OF AND MEANS FOR ADJUSTING FLOW RATES OF FLUIDS THROUGH FORMATIONS TRAVERSED BY BOREHOLES Filed May 9, 1942 2 Sheets-Sheet 2 9|] 30 87 85 90 3 v 92 gg El 6 ,.f/

G) G) @D I, F QII E i w x x x x x x if; 0 0 C 'A" A x x x x x l o C C I it, x x x x x ...'i -f i v s x x x x x x s I O D C y C 1'. B x x x x x x .lj o o o o X X X X X X x Producing wen T O njzdon well faknq .0. Too much wczrer @mmm-@MM Patented July 4, 1944 METHOD OF AND MEANS FOR ADJUSTING FLOW RATES OF FLUIDS THROUGH FOR- MATIONS TRAVERSED BY BOREHOLES GeralfLL. Hassler, Berkeley, Calif., assigner to Shell Development Company, San Francisco, Calif., a corporation of Delaware Application May 9, 1942, Serial No. 442,378

7 Claims.

The present invention relates to methods of drilling and producing oil and gas wells and pertains more particularly to methods of determining the properties of formations traversed by a borehole. i

Generally, in oil wells, the strata traversed by the borehole vary considerably in their ability t conduct fluid therethrough. This difference in permeability of the various strata gives rise to considerable diiliculties, particularly in repressuring or flooding systems for secondary recovery of depleted oil Isands wherein a. complete or uniform recovery from the various oil-bearing strata cannot be obtained, since a high rate of recovery of oil is effected from the highly permeable strata while a low recovery is attained in the less permeable regions. This condition occurs when repressuring is indiscriminate, as when the flooding fluid, such as air, gas, or water, is forced into a formation from a .pressure well without regulation of the pressure, volume, and velocity as between strata of dierent permeabilities.

To overcome these diflculties, heretofore it has been proposed to place in the injection well of such systems a tubular sleeve Withspaced rings of openings of various sizes and with means to seal off ythe space outside the sleeve between the rings of openings, whereby the flow of fluid into the various strata is controlled by the size of opening communicating with the strata opposite said opening. However, this device is unsatisfactory in that permeability measurements must first be made, then a special sleeve constructed to correspond to said measurements and flow rate calculations, and subsequently the sleeveY 'a permeability-measuring device without the use of expensive and cumbersome electrical cables.

It is also an object of this invention to provide means to measure the effective permeabilities of strata traversed by a borehole and to regulate the amount of flooding iluid taken by the strata to the desired values without the necessity of extremely accurate correlation of permeability measurements with depth and location of liner sleeves or the like.

It is a further object of this invention to provide surface control means, whereby signals can be transmitted through the mud fluid, drill pipe, or walls of the borehole, for actuating permeability-measuring instrument in a well borehole.

It is still another object of this invention to provide a device for adjusting the effective permeabilities or flow resistances of the desired porous formations in an injection well of a waterflooding system toward a more nearly uniform medium value, whereby ooding water will pass into the various formations at substantially the same rate.

It is also an object of this invention to provide a method and apparatus for isolating a stratum traversed by a well from the rest of the borehole, flowing a liquid into said stratum., measuring the liquid ow rate at a point close to the point of injection into the stratum, and transmitting the measurement to the well surface by means of vibration signals.

It is a still further object of the present invention to provide means for measuring the rate of flow of a liquid into a stratum traversed by a well borehole, and, depending on the measured rate of liquid flow, either decreasing its effective permeability by partially plugging said stratum with finely divided inert material, or increasing its effective permeability by means or" acid in order to obtain a predetermined rate of liquid now into said stratum.

Other objects will be readily apparent from the following description, taken in reference, to the drawings, wherein:

Figure I is a longitudinal sectional view of the upper portion of a preferred embodiment of a device used to carry out the present invention, showing said device in operative position in a borehole.

Figure II is a continuation of Figure I, showing the lower portion of said device.

Figure III is a cross-sectional view taken along the line III-III of Figure I.

Figure IV is a schematic vertical sectional view of an oil well with the present device positioned therein.

Figure V is a diagrammatic view of a water ood lease map showing a section of the oil field before treatment and a section after treatment according to the present invention.

Generally, the present invention resides in isclating or packing ofi a stratum traversed by a -we1l from the rest'of the borehole, for example,

Packed-olf space in the borehole, wherein its rate of eiilux may be measured.

Since the present invention is particularly ap- 4 plicable to the regulation of the ow of ooding or repressuring fluid through the various strata of an injection well of a flooding or repressuring system, it will be described in relation thereto.

After the effective permeability or flow resistance of a stratum in an injection well has been measured, the walls of the borehole in that stratum are suitably treated to adjust the uid flow rate to the desired value by flowing into the stratum together with the fluid either a permeability decreasing or plugging material, such as a finely divided, preferably acid-soluble, solid, e. g. chalk, oyster shells, etc., or a permeability increasing material such as an acid capable of forming Water-soluble salts with the earth formation, for example, hydrochloric or hydrobromic acids, solvents, for example pyridine or nitrogen bases, etc.

The permeability measurements are preferably indicated at the surface and the control of the expansion of the packers and injection of the plugging material or acid are eected by means of signals or vibrations, such as sound waves or 'the like, transmitted through the drill stem, the

borehole walls or fluid filling the well, or other wave transmission paths available in the well. However, if desired, insulated electric cables may be used in whole or in part to effect such measurement of control communications.

I Referring to Figures I, II and III of the drawings, a preferred embodiment of a device for carrying out these operations is contained in a tubular housing I I (Figure IV) which may be formed of coupled sections Ila, I Ib, llc, and Ild. The lower section IIa, as shown in Figure II, is pref- A erablyformed with a tapered lower end I2 and of two tubular housing sections IIb and llc, and

extending therethrough is a tubular member or pipe 20. End plates 22 and 23 and intermediate plate 2I, Which also acts as a coupling for the housing sections IIb and llc, surround the pipe 20 and divide the annular space thereabout into two tanks 24 and 25, which may be filled with chalk suspension and acid, respectively, by means of filler plugs 26 and 21. The tanks 24 and 25 are I l respectively provided with ports 28a and 28h in their'upper portion and ports 29a and 29h in their lower portion, which ports communicate with the central channel through pipe 20. A tubular element 30 is reciprocable coaxially in the central pipe 20 and carries valve members 3Ia,

actas lib, 3Ic and 3Id which normally close the ports 28a, 29h and 29a and 29h in tanks 24 and 25. Stops 50 within the pipe 20 andribs v5I on the tubular element 30 limit the reciprocation of said element 30. A flexible 'conduit 59 attached to the lower end of the tubular element 30 communicates with the interior of the'inflatable packers I6.

Preferably directly above the upper end plate 22 of the tank 24 is a"chamber 32 which contains a suitable flowmeter 33, shown also in Figure HI. A conduit 34 supplies fuid to the flowmeter 33 from the outside of the housing Ilcv and a second conduit 35 communicates with the centra1 pipe 20 for discharging thereinto iiuid from the owmeter 33, which thereby is adapted to measure the fluid fiow into the centra1 pipe 20. The owmeter 33 is also adapted to actuate an impulse sender and may, for example, be of the common water meter or rotary piston type, which comprises, as shown more fully in Figure III, an eccentric cylindrical rotor 36 and a reciprocable slide barrier 31 arranged to be forced against the rotor 36 by resilient means, such as a spring 39, acting on the outer end of the slide 31, which is positioned between the inlet and outlet conduits 34 and 35. Fluid entering the space between the rotor 36 and the owmeter housing 33 from the inlet conduit 34 on one side oi the barrier 31 and passing to the outlet' conduit 35 on the other side of the barrier 31 causes the eccentric rotor 36 to rotate. The reciprocation of the barrier or slide 31 caused by the rotation of the eccentric ,rotor 36 cyclically operates an impulse sender switch or a clicker, in any suitable manner, such as by closing the electrical circuit through contact 36 and spring 39, to which are attached electrical conductors leading to the sending apparatus to be subsequently described.

The upper end of the reciprocable tubular element 30 extends through chamber 32 and flowmeter 33 therein and through a packing gland 40 into a motor chamber 4I. Any suitable arrangement of power means may be provided in this chamber 4I for reciprocating at will the valve-carrying tubular element 30 and for pumping uid into the expansible packers I5 through tubular element 30 and exible conduit 59. For example, the tubular element 30 may be recipro-v cated by means of' an electric motor 45 which rotates a Worm gear 46 engaging a gear' 41 which rotates a gear 46 engaging a rack 49 carried. on the upper end portion of the tubular element 30. A second electric motor 55 operates a pump 56 having an intake 51 communicating with the outside f the housing II. The pump 56 discharges into a flexible conduit 58 which connects to the upper end of the reciprocable tubular element 30.

The upper housing section I Id provides a water tight compartment for batteries 65, a relay set 66, signal-receiving means, such as a sound receiving cone 61, and signal-transmitting means, such as a transmitter cone or horn 68. The relay set 66, which may comprise suitable amplifying means, is adapted to yactuate the pump motor. 55 and valve-operating motor 45 in response to predetermined signals transmitted from the surface to the receiving cone 61. For this purpose, any suitable type relay system 66 may be used, and may comprise for example, an impulse-activated system such as is used in dial telephone systems or a magnet system which will set up or generate a current when a diaphragm vibrates, as described, for example, in

or through a suitable amplifying system. The

assaasa current actuating impulses may be of low frequency so as not toV interfere with or to be actuated by the signal or impulse output of the transmitting cone 88 which may operate on a high frequency. I1 desired, the relay set 68 may comprise several tuned frequency circuits and thus be actuated by signals or vibration of different frequencies in a well-known manner, such, for example, as described in thev Mattingly et al. Patent No. 2,255,721, while the transmitting cone 83 which reports the ilow rate, may be operated at still other frequencies.

At the surface there may be provided suitable equipment, such as, for example, a portable unit mounted on a truck 85, as shown in Figure IV. The truck 85 may carry a small derrick 85, a

l drum 81 for the wire line 16, a vibration or sound transmitter 88 and receiver 88, together with amplifying and filter circuits and an instrument control board 90, and supply tanks 9| for acid and chalk suspension. Likewise, it is preferable to provide some means, such as a pump 82 which may be located at the well head for high pressure` injection of flooding fluid, such as water, during the period of treatment.

In operation of the preferred embodiment of this invention, the assembled device comprising the housing Il is lowered to the bottom of a borehole by means of a wire line 16, derrick 86, drum 81, etc. When the device reaches the desired depth, a particular sound, vibration, impulse or a series of impulses is initiated at the surface by means of the transmitting device 88, which travels down through the medium lling the borehole or the walls of the borehole, etc., to the receiving cone 61, and is conducted thereby to the relay set68. In response to this particular signal, the relay set 66 selectively actuates the pump motor 55 and pump 56 in a predetermined manner, depending on the nature of the signal.

' On a first signal, fluid from the borehole is caused to be forced by the pump 56 through conduit 58, the tubular element and the conduit 59 and thence into the packers I5, which are thereby expanded against the borehole walls to seal olf or isolate a portion of the borehole.

The flooding or repressuring fluid, such as. for example, water, air, gas, etc., is injected into the borehole under high pressure by pump 82 and the main portion thereof flows down around the housing- Il and through the by-pass channel I3 and into the formation but not into that portion isolated between the expanded packers l5. A small portion of this flooding uid ilows through the conduit 34 into the flowmeter 33 and out through conduit 35 into the annular space between the tubular element 38 and the walls of the central pipe 20, and thence down into the housing member Ila and out through the perforations I4 into the formation sealed off betweenthe packers I5.

It will be seen that there is only a small pressure difference across each packer, since the pressure of the flooding fiuid in the space between the packers is only slightly lower than the pressure above and below the pair of packers by the amount of the resistance of the ilowmeter and conducting tube 20. It is therefore only necessary to apply suiiicient pressure to the flooding water to cause the operation of the flowmeter 33 and the chemical tanks 24 and 25.

The rate of flow of fluid into the sealed-ofi.'

zone is measured by the flowmeter 33 and the reciprocation of the dividing barrier 31 due to the rotation of the eccentric rotor 38 causes the horn or transmitter cone 88 to be actuated periodically. If desired, instead, the reciprocation of the barrier 31 may be arranged to produce clicks which can be amplified and conducted to the-transmitter cone 88. The series of actuatins of the horn or transmitter cone 68, as can be .noted at the surface by receiver 89 and control board Il, will be fast if the zone is so permeable that it takes much fluid, or will be slow if the Zone takes a small amount of fluid.

In the case where the flow is too great, the operator sounds another note or signal of particular frequency into the borehole, which causes the relay set 68 to energize the valve-operating motor 45 in the proper direction for moving the slidable tubular element 38 and valves 3l upwards into a position opening the ports 28a and 29a of the upper chalk-containing tank 24; the flow in the central channel 20 is thereby temporarily partially diverted through the chalk tank 24. By thus adding small increments of chalk to the fluid flowing to the sealed-off or isolated strata so as to build up a thin mud cake, and by continually observing at the surface the flow rate as reported by the iiowmeter 33 and transmitter 88, the operator can adjust (that is, in this case, restrict) the ow rate to a desired medium value. After enough chalk suspension has been added to the stream of fluid to obtain the desired restricted flow rate into this stratum, another note is sounded at the surface to .cause the motor 45 to return the valve-carrying element 30 to neutral position.

In the case where the flow is-too small, that is, less than a predetermined medium rate, the operator initiates another particular signal by transmitter 88 at the surface, which signal on travelling down through the borehole and impinging on the receiving cone 61 causes the relay set 88 to energize the valve-operating motor 45 in the proper direction for moving the slidable tubular element 38 and valves 3l downwards into a position opening the ports 28h and 29h of the lower acid-carrying tank 25. The iiow of flooding water or other uid through the central channel 20 is thereby temporarily partially diverted into the acid tank 25. A slidable annular separator or spacer above the acid in the acid tank 25 is preferably provided to prevent the water entering the upper port 28h from diluting the acid. The acid thus added to the flooding water passes into the section of the formation being tested and increases its permeability, allowing greater fluid flow thereinto. Preferably, the ports 28h and 28h are opened for short periods by first sounding a signal causing the valvecarrying element 30 to move downward and then closely thereafter sounding a signal causing the element 30 to move back to a neutral position. These signals may be repeated until enough small increments of acid are thereby injected into this isolated formation to increase the flow rate to the desired medium value while the flow rate is being continually measured and reported to the surface by the flowmeter 33 and transmitting cone or horn 68.

The packers I5 are then deflated by stopping or reversing the pump 55, which is accomplished by the relay set 5G in response to a particular note or set of Vsignals issued by surface transmitter 88, andthe device raised up to a position opposite the next higher stratum or section of the borehole. The above operation of setting the packers l5 and determiningthe rate of now of liquid into the formation between the packers I5 are repeated and thereafter the proper treatment with acid or chalk is applied, depending upon the permeability of this section of the borehole as measured and reported to the surfield, the treatment of the injectionwells in the above manner results in each injection Well taking a balanced share of the flooding water, which desirable condition is represented by the uniformity of the dots signifying injection wells in the lower treated portion B as contrasted to the non-uniformity of the upper untreated portion A of the water flood lease map shown in Figure V.

It is readily apparent that various changes and modifications can be made in the abovedescribed method and apparatus Without departing from the spirit of the invention, one essential feature of which is the step of measuring the rate of ow of fluid through a porous formation traversed by a borehole at a point closely adjacent to said porous formation. Thus, for example, if desired, instead of controlling the abovedescribed device by means of vibration or sound impulses transmitted through the medium filling the borehole. communication and control may be partially or completely accomplished directly by means of a cable containing insulated electrical conductors. Also. the present invention may be applied to other than injection wells of ooding systems. Thus, for example, the rate of flow of liquid .from/ porous formations traversed by a borehole may be measured by placing expansible packers, a suitable owmeter and reporting system, such as in the above-described flow adjusting device, at a position in the borehole with the flowrneter closely adjacent the' point of efflux of fluid from the formation sealed off from the rest of the borehole between the two expansible packers.

I claim as my invention:

l. A method for substantially equalizing fluid flow into the various porous strata trayersed by an open borehole of uid injection wells of ooding or repressuring systems, comprising successively applying to portions of the borehole the treatment comprising the steps of4 packing off a desired vertical portion of the borehole, forcing a uid into the borehole walls surrounding said portion, measuring the rate ,of said flow at a point adjacent said portion, indicating at the surface of the well said measured flow rate, and

lstantially equalized.

2. In a device for adjusting the rate of fluid flow into the various strata traversed by an injection well of a flooding system, a housing adapted to be lowered into a borehole, a pair of tion traversed by the borehole, passage means in said housing opening outwardly above and between the packer means for directing fluid ow into said packed-off section of the formation, meter means in said passage means for measuring the ow of fluid therethrough, a reservoir in said housing containing a comminuted inert material, a second reservoir in said housing containing an acidic material capable of forming water-soluble salts with the earth formation,

said reservoirs having openings communicating with vsaid passage means, valve means closing said openings from said reservoirs to said passage means, and controlmeans operablefrom the surface for actuating said valve means to open and close said openings for selectively adding the contents of one of said reservoirs to the fluid flowing into said formation.

j 3. In a device for adjusting the rate of fluid flow into the various strata traversed by an injection well of a flooding system, a housing adapted to be lowered into a borehole, a pair of axially spaced expansible packer means mounted therein for packing oi a section of the formation traversed by the borehole, channel means in said 1 housing opening above and below the packer means and adapted to allow the main portion of duid flowing down through the borehole to bypass said packed-off portion, passage means in said housing opening outwardly above and between the packer means and adapted to cirect a smaller portion of the iiuid flow into said packedoff section of the formation, meter means in said passage means for measuring the ow of uid therethrough and means for adjusting the flow characteristics of said formation comprising a reservoir in said housing containing a comminuted inert material, a second reservoir in said housing containing an acidic material capable of forming water-soluble salts with the earth formation, said reservoirs having openings communicating with said passage means, and means controlling the opening and closingof said openings for selectively adding the contents of one of said reservoirs to the uid flow into said formation.

4. In a device for adjusting the rate of fluid ow into the various strata traversed byv an injection well of a ooding system, a housing adapted to be lowered into a borehole, a pair of axially spaced expansible packer means mounted therein for packing olf a section of the formation traversed by the borehole, channel'means 'in' said housing opening above and below the well, and means for adjusting the ow characteristics of said formation comprising a reservoir in said housing containing a comminuted inert y material, a second reservoir in said housing containing an acidic material capable of forming water-soluble salts with the earth formation, said reservoirs having openings communicating with said passage means, and means controlling the opening and closing of said openings for selec` tively adding the contents of one of said reservoirs to the fluid owing into said formation.

5. In anv apparatus for treating formations traversed by a borehole a housing adapted to be lowered into the borehole, at least two expansible packers vertically spaced from each other carried by said housing, means for expanding said packers into contact with the walls of the borehole, whereby a portion thereof is sealed oilr by said packers, passage means in said housing opening outwardly above and between the packer means and adapted to direct fluid flow into the sealedoiI portion of the borehole between said packers, metering means in said passage for measuring said flow, means for conveying the indications of said metering means to the surface, a reservoir in said housing containing a substance capable of modifying the resistance to fluid flow through the formation, said reservoir having an opening communicating with said passage means. and means controlling the opening and closing of said opening for injecting said substance into the borehole between said packers.

6. In an apparatus for treating formations traversed by a borehole, a housing adapted to be lowered into the borehole, at least two expansible f packers vertically spaced from each other carried by said housing, means for expanding said packers into ,contact with the walls of the borehole, whereby a portion thereof is sealed oir by said packers, passage means in said housing opening outwardly above and between the packer means and adapted to direct uid iiow into the sealed-oil. portion oi' the borehole between said packers, metering means in said passage for measuring said flow, means for conveying the indications of said metering means to the surface, a reservoir in said housing containing a substance capable of modifying the permeability of the borehole walls, said reservoir having an opening communicating with the passage means, valve means closing said opening from the reservoir to said passage means, and relay means actuated by an impulse transmitted from the surface for opening and closing said valve means to control the flow of permeability modifying substance through the opening in said reservoir to the sealed-off portion of the borehole packers.

7. A method for substantially equalizing fluid flow into the various 'porous strata traversed by an open borehole, comprising successively applying to portions of the borehole the treatment comprising the steps of packing oif a desired vertical portion of the borehole, forcing a fluid into the borehole walls surrounding said portion, measuring the rate of said ow at a point adjacent said portion, indicating at the surface of the well said measured flow rate, and while maintaining said vertical portion packed off changing said flow rate by injecting into said portion of the borehole a iiuid comprising' a substance capable of modifying the resistance to fluid flo'w through the formation to a predetermined value whereby the resistances to fluid iiow of the various, portions of the borehole are substantially equalized.

GERALD L. HASSLER.

between, said

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