US2595578A

US2595578A - Fluid ingress location in wells

Info

Publication number: US2595578A
Application number: US135908A
Authority: US
Inventors: Ralph E Hartline; Robert P Murphy
Original assignee: Stanolind Oil and Gas Co
Current assignee: Stanolind Oil and Gas Co
Priority date: 1949-12-30
Filing date: 1949-12-30
Publication date: 1952-05-06
Anticipated expiration: 1969-05-06

Description

May 6,1952 R. E. HARTLlNE ET AL FLUID INGREss LOCATION 1N wELLs 3 Sheets-Sheet 2 Filed Deo. 30, 1949 L F. In..

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f l/ f ...Hg l/ I Z Z E 1H /VVN /H T u mw mw u wwa wwf: @L u e /f Fresh Water 23 INVENTORS: Ralph E. Hortline @Sllml ATTO RN EY May 6, 1952 R. E. HARTLINE ET AL FLUID INGREss LOCATION 1N wELLs 3 Sheets-Sheet 3 Filed Deo.

o Conductivity Recorder /Fresh Woer Top of Fresh Woier Column Leuk ol Casing Sull Water Zone Sali Water Zone con? IY Static Fluid Level Produclng Fluid Level Oil Sand :ie shale fi? oil san'd Saltwater Sand III f @im iw Fresh Woter lllllh@ il Fig.7

. INVENTORS: Ralph E. Hartline BY Robert P. Murphy ATTORNEY Patented May 6, 1952 UNITED STATES PATENT GFFICE FLUID INGREss LOCATION m WELLS Ralph E. Hartline and Robert P. Murphy, Tulsa,

Okla., assignors to Stanolind Oil and Gas Company, Tulsa, Okla., a corporation of Delaware Application December 30, 1949, Serial No. 135,908

(Cl. V75- 182) desired hydrocarbon fluids, the invention will be described with particular reference to such wells, although its utility is clearly not so limited.

Numerous attemptshave been made, and some commercial success has been attained in solving problems of water-entry location in oil and gas wells, but all of the methods heretofore employed have had their usefulness somewhat limited by certain difficulties and drawbacks. Almost all of such methods have employed steps of well conditioning or preparation which required extended periods of time and very careful manipulation of the well and of the conditioning fluid and equipment. Extreme and even impractical precautions have been necessary to avoid overbalancing the fluid pressures of the exposed formations in wells, whichV overbalancing could result in forcing into the formations foreign fluids that would later mask the identity of true formation fluidsl in subsequent testing. In many methods the success or failure of the testing process has been dependent upon the manner of distribution of a particular testing material through the well fluids, such material being also more cr less expensive and hazardous to handle in the case of acids or radioactive tracing agents and solutions. In addition, with some methods the signicant indications are of such short duration that they could be completely missed if the measuring or detecting equipment happened to be at a different level in the well at the critical time. In most of such prior art methods also the tests are carried out with the well under quite different conditions of production from those prevailing during the normal production of the desired oil and gas. Also a drawback in some cases is the fact that the insertion of additional tubing into the wall, or more or less handling of the well production tubing and pumping equipment, may be required, all of which add greatly .to the time and expense of the testing operation.

In view of the fact that most of the foregoing disadvantages and drawbacks are minimized or are completely overcome in our invention, some of the objects of the improved testing procedure of the invention may be briefly enumerated as follows: (l) to provide well-conditioning steps of a very simple nature, which are capable of being carried out from the surface in a comparatively brief time, and which cause a minimum of interference with the normal production of the well; (2) to provide a conditioning process involving no possibility of overbalancing the static formation fluid pressures and causing intrustion of foreign fluids into the permeable formations; (3) to vemploy one of the least expensive and hazardous of all possible conditioning agents, namely, fresh orsaltwater; y(4) to produce in a well a semipermanent indication or pattern which is capable of being repeatedly observed as long or as .of our invention by a testing method which involves generally the following steps: rst, producing the well to lower its bottom-hole pressure substantially below its static value, preferably withdrawing the well fluids through the well tubing from a point near the bottom of the well, or at least from a depth as great as testing is desired; then, rapidly introducing into the well annulus a quantity of conditioning liquid, preferably water or brine miscible with the formation liquid to be located but contrasting with it in some measurable characteristic such as electrical conductivity, which quantity is calculated to increase the bottom-hole pressure by some substantial fraction of, but less than all of the total amount it was initially reduced; continuing to produce through the well tubing and to introduce conditioning liquid into the annulus at some reduced rate, less than the producing rate, while the rapidly introduced liquid falls through the annulus liquid column to the well bottom, where tamination of the entering formation fluids, all the while producing the Well through the tubing to induce flow from the formations and simultaneously to draw down the consolidated column of conditioning liquid in the annulus through the test zone. To these steps may advantageously be added in many wells a preliminary washing step to free the oil column and the well bore of any salt accumulations which could reduce the contrast between the conditioning and the formation liquids by initially contaminating the conditioning liquid.

If all of these steps are correctly carried out, the bottom-hole pressure in the well, after the beginning of the operations, is always less than its static value, so that there is always more or less ilow from the formations into the well bore. Overbalancing of the formation pressures with intrusion of foreign fluids into the formations,

giving false indications of the formation fluid j.

content in subsequent testing, is positively prevented. On the other hand, the formations are tested while producing intothe well bore (and into the descending conditioning liquid column in the annulus) at any desired rate, even approaching their ordinary producing rate.

This will be better understood by reference to the accompanying drawings forming a part of this application, taken with the following detailed description. In these drawings in which the same reference numerals are applied to the same or corresponding parts in the different figures:

Figures 1 to 6, inclusive, show in cross section a typical well and the fluid conditions therein before and during the various steps of the testing process of the invention; and

Figure 7 shows a log of fluid conductivity as a function of depth, correlated with the fluid-producing formations of the adjacent figures.

Referring now to these figures, and to Figure 1 in particular, a well 9 is shown as penetrating a variety of producing and non-producing formations including, for example, a salt Water producing sand I0, an impermeable shale Il, an oil and water producing sand or limestone producing oil from its upper portion I2 and water from its lower portion I3, another impermeable shale bed I4, a salt water stratum I5, a shale I6, an oilbearing sand I 'I, and finally a salt water bearing stratum I8. Well 9 is equipped with a casing I9 cemented in the impermeable bed I I, but for purposes of illustration it will be assumed that there is a leakage of salt water from the salt water sand I down around the casing seat as indicated at 20. Extending through the casing I9 is a production tubing 2| having at its lower end a pump 22 with an inlet port 23, the pump 22 being operated by a conventional sucker rod string reciprocated by a pumping jack 24 located at the ground surface 25.

Figure 1 shows the fluid column conditions which might exist in well 9 after it has reached static equilibrium, at some time following. the stopping of production through the tubing 2 I. After pumping has ceased, the fluid level within the annular space 26 between tubing 2| and casing I9 rises until it reaches the level 21, desig, nated as the static fluid level, at which the pres-' sure exerted by the annulus fluid column exactly balances the reservoir pressure of the fluids within the formations, and production thenceforth ceases. This bottom-hole pressure is herein called the static bottom-hole pressure. By virtue of the oil and water being immiscible and of different specific gravities, the fluid column in the well annulus separates after a time into two portions comprising an upper body 28 of oil and a lower body 29 of salt water, separated by a sharp interface 30, which frequently stands at some distance above the pump inlet port 23.

Figure 2 illustrates the changed conditions which exist in Well 9 some time after production has been under way, with pump 22 removing well fluids through tubing 2l to the ground surface 25. After a sufficient period of time of producing the well at a given rate by means of pump 22, the fluid level of the oil column 28 is drawn down to a new equilibrium level 3|, which lmay be termed the producing fluid level where, due to the decreased bottom-hole pressure exerted by the shortened fluid column in space 26, which pressure is less than the reservoir pressure existing within the formations, the well formations capable of fluid production then produce such fluids at a total rate which is exactly equal to the rate of removal of the fluids by the pump 22. In this dynamic or producing equilibrium condition the oil-water interface 30 is found to have dropped to the level of pump inlet 23, oil from formations I2 and I'I enters the oil body 28 and is produced by the pump 22, while salt water from the leak 29 and the formations I3, I5, and I8 enters the well and either descends through the oil body 28 in globules to inlet 23 or mingles with the salt water body 29 which is` similarly drawn through inlet 23.

With the bottom-hole pressure thus lowered substantially below its static value, though not necessarily all the way to the producing equilibrium value, the well is in a condition for the conditioning-liquid introduction steps of our invention. As it has been found that in many wells there are salt accumulations, either on the outside of tubing 2| or the inside of casing I9 or within the oil column 28, an initial washing step is preferably performed, as shown in Figure 3, by providing at the surface 25 a supply tank 'J5 of fresh water of which the rate of introduction into the annular space 29 is controllable by a valve 36. It is assumed that the pump inlet 23 is at least as deep as testing is desired near the bottom of the well 9, or has been lowered to that position at some time prior to the test by lengthening the tubing string 2 I, as it is ordinarily not possible to circulate the conditioning water below the pump inlet level. In any event, fresh water 3'I from supply 35 is introduced into space at a low rate while pumping is continued at a normal rate by pump 22 through tubing 2 I. Unless otherwise specified, the term' rate as applied to well production, liquid introduction, pumping, and the like in this specification is to be understood as meaning weight cr mass per unit time, rather than volume; and the term normal as applied to the pumping rate is simply that at which the pump customarily operates, no change in the strokes-per-minute or strokelength being made from the settings used during daily production of the well.

On this basis the rate of introduction of thel washing water 31 may be typically from 10 to 20 per cent of the pumping rate of the well; but, if water is readily available, it may be introduced at any higher rate not exceeding the pumping rate; for example, up to about '75 per cent of the pumping rate. As water 3'! falls through the space 26 and through the oil column 28 to the bottom of the well, it dissolves any salt depositions present and is then removed from the well by the pump through the tubing 2 I. This washing may continue over a period of several hours.

A|13 at the ground surface.

from 12 to 48 hours having been found generally 'adequate to remove the salt deposits found in most wells. It will, of course, be understood that this preliminary washing step may be dispensed with in wellsuwhere salt deposits are absent, or where it is unnecessary to have the largest possible contrast in electrical conductivity between the conditioning water 31 as it arrives at the Well bottom and the salt water 23 produced by the well.

At the end of the preliminary washing operation, the well, still being produced through tubing 2| and with the bottom-hole pressure substantially below its static value, is in a condition for starting the specific conditioning procedure of our testing process. In accordance with our invention, knowing the amount of bottom-hole pressure reduction, for example, by fluid level measurements using the test electrodes of the jinvention, a quantity of fresh water 31 is introbottom-hole pressure so that the well formations are always producing some fluids into the well bore, approximately half this maximum amount of water is the amount most often employed.

Either previously or at this time, a fluid-conductivity testing device is lowered into the well annulus 26, which device consistsof an electrode carrier 40 mounting a pair of insulated electrodes 4| exposed to the Well fluids and suspended by an armored, insulated conductor cable 42 from a reel Appropriate slip rings, brush'es,vand electrical leads connect the armor of cable 42 and the insulated conductor within it to a source of alternating current 41| and a Arecorder 45.

As appears in Figure 4, the body of water 31, being rapidly introduced, starts to fall in globules of substantial size through the oil column 28. During this period of rapid water introduction and thereafter, pump 22 continues to withdraw fluid from the bottom of well 9, while the well formations continue to produce but at a reduced rate because of the increased bottom-hole pressure created by the added fresh water in the annulus fluid column. Electrodes 4| are lowered through the well annulus to a position adjacent the pump 22 where they are able to detect the approach and arrival of the fresh water 31 at the well bottom, or they may be traversed through the fluid column to follow the progress of the fresh water downwardly.

After the rapid introduction of c-onditioning water as shown in Figure 4 and still during the tir'iues to lift fluid-at about its normal rate during this interval. Y ..5

The downward progress of the main body of conditioning water 31 is either' readily followed by the test electrodes 4|, or its approach to the level of pump 22 observed by stationing the electrodes there. Ultimately the major portion of the conditioning water 31 collects at the well bottom in a consolidated column, as shown in Figure 5. The height of this column is surveyed by the electrodes 4| until it is observed that the entire test section of the well 9 is covered, plus enough additional water 31 above the test section; either consolidated or still falling through the oil, to form a reserve supply to be drawn down in subsequent testing.v

YIt is desirable but not necessary to interrupt temporarily the operation of pump 22 when the approach of the conditioning water 31 to the well bottom Ais rst noted, as` otherwise a portion of the conditioning water would be removediwhile the remainder is consolidating, and the. supply available for testing would be reduced. This step is illustrated in Figure 5, where the introduction of water at the medium rate, one-half to threequarters of the pumping rate, has been discontinued, and the pump 22 has been shut down following the approach of the first conditioning water 31 to the well bottom, as detected by the electrodes 4|. After a brief period it is found by traversing the fresh water column with the electrodes 4| that the water column height has risen past the producing formations andv extends into the cased portion of the well.

Production of the well is then resumed, as shown in Figure 6, either with or without a medium rate of introduction of water 31 from the surface 25 into the annulus 26 and with the bottom-hole pressure somewhat below its static value. Part of the fluid then produced by pump 22 through tubing 2| are those coming from the column of conditioning water beingv drawn down from the casing through the open part of the well bore, while the remainder are those coming from the well formations due to the bottomhole pressure being under its static value. Accordingly, a'resistivity pattern due to contamination of the downwardly moving conditioningwater column by entering salt water from the formations appears as shown in Figure 1.

At this point it should be noted that the relative flow rates of the conditioning water column and the Aentering well fluids are readily controllable from the surface. The conditioning water input into the annulus 26 is simply regulated to hold the bottom hole pressure at the desired reduced pressure value below static. Thus for a. large reduction in bottom-hole pressure, the well production is large compared to the downward flow of conditioning water; for a small reduction in bottom-hole pressure, the reverse is true-the well production is small and the downward conditioning-water flow is large. The actual magnitudo nf' thcf'nrnssurn rednntnn fm* a tending all the way from near static to near a normal producing equilibrium.

A typical log of the fluid conductivity as a function of depth is shown in Figure 7, correlated withy the formations shown in the adjacentgure. The interpretation of this log is as follows: a small layer of freshwater 31 overlying the nonconductive. oil body 28, and globules of water 31 falling through the oil produce the indications seen at 50, I, and 52. The top of the main fresh water column (and the base of the oil layer). appears at 53. The casing shoe leak 20 causes the sharp conductivity increase at 54, while the straight portion 55 of the curve shows no further ,water entry over the corresponding interval.l

The two gradual increases in conductivity over the

intervals

56 and 51 delineate two separate zones of salt-water entry, While the final high value of conductivity 58 may or may not indicate a bottom water entry. Salt-water stratum I5 shown by the conductivity increase 51 is par'- ticularly susceptible to being shut olf, lying as it does, between the impermeable beds i4 and I6.

A check on the production of well El below pump inlet 2S can be obtained at the end of the testing operation by shutting down pump 22 and letting the well formations produce into the annulus. If the indication 58 appears to move upward, there is fluid production below inlet 23; if it is stationary, there is not.

Since, during testing, the pump 22 operates at a steady rate, and the annulus iluid level can be maintained constant by addition of water from the surface, the pattern of fluid conducN tivity obtained due to formation water entering the downwardly moving conditioning-water column at a constant rate, is a stable or semipermarient one. Therefore the traversing of electrodes 4l through the well test section may be repeated as many times as desired to prove the stability of the contamination pattern. In fact, the usual procedure is to traverse the electrodes and record the conductivity more or less continuously until it is seen that the conductivity pattern is permanently established by the fact that it does repeat.

It should be noted that our invention is not limited strictly to the detection of salt water using fresh water as a conditioning liquid. We has found, for example, wells in which the conductivity of the water produced by the formations approaches that of normally fresh water, in which case the preferred conditioning liquid is one having a lower conductivity than the produced well water, such as is obtained by the addition of an electrolyte such as sodium chloride to otherwise fresh water conditioning rnediurn. However, the indications produced by such a technique are analogous to those illustrated in Figure 8 except, of course, that the contamination of the conditioning liquid column by the well fluids decreases rather than increases the average electrical conductivity of the mixture. Similarly, the permanence and character of the pattern obtained with the well in a dynamic state of production and conditioning water being continually introduced are the same as have been shown. V

While we have thus described our invention by giving in detail the sequence of steps by which we arrive at the desired results, it will be apparent to those skilled in the art that certain modifications of these outlined steps are possible Without affecting the validity of the results 0btained. The invention, therefore, should not be considered as limited strictly to the described procedure, but its scope is to be ascertained from the scope of the appended claims.

We claim:

1. The method of testing a well which comprises 'the steps of first producing said well to create a substantial reduction in the bottomhole pressure below its static value, then introducing rapidly into the well annulus a quantity of conditioning liquid calculated to increase said bottom-hole pressure by a substantial portion of said reduction, continuing to produce said Well and to introduce said conditioning liquid at a reduced rate which is a substantial fraction of the well-producing rate, until said conditioning liquid reaches the bottom of a test zone in said Welland forms in said well annulus a column extending at least through said zone, and measuring as a function of depth a property of said conditioning liquid characterizing its contamination by entering formation fluids, while producing said well and drawing down said conditioning liquid column through the well test zone.

2. The method of testing a well which comprises the steps of first producing said well at a substantial rate and for a substantial period of time, whereby there is created in said well a substantial reduction in the bottom-hole pressure below its static value, then introducing rapidly into the well annulus a quantity of conditioning liquid calculated to increase said bottom-hole pressure substantially but in a total amount less than said reduction, continuing the producing of said well and the introduction or" said conditioning liquid, said continuing introduction of conditioning liquid being at a rate which is a substantial fraction of said continuing well-producing rate, until said conditioning liquid reaches the bottom of a test zone in said well and forms in said well annulus a column extending at least through said zone, and measuring as a function of depth a property of said conditioning liquid characterizing its contamination by enter'- ing formation fluids, while producing said well and drawing down said conditioning liquid column through the well test zone.

3. The method of testing a, well which comprises the steps of rst producing said well at a substantial rate and for a substantial period of time, whereby there is created in said well a substantial reduction in the bottom-hole pressure below its static value, introducing into the well annulus at a slow rate and over an extended period of time a conditioning liquid miscible with a well liquid to be determined but contrasting therewith in some measurable property, then rapidly introducing into said well annulus a quantity of said conditioning liquid calculated to increase the bottom-hole pressure substantially but in a total amount less than said reduction, continuing the producing of said well and the introduction of said conditioning liquid at reduced rate which is a substantial fraction of said continuing well-producing rate, until said conditioning liquid reaches the bottom of a test Zone in said well, temporarily discontinuing said producing and introduction of conditioning liquid until said conditioning liquid forms in said well annulus a. consolidated column extending at least through said test zone, resuming the producing of said well at a substantial rate and the introduction of said conditioning liquid at a substantial fraction of said producing rate, and measuring as a function of depth a property of said conditioning liquid characterizing its contamination by entering well iluids, while producing said well and drawing down said conditioning liquid column through the well test zone.

4. The method of testing a well which comprises the steps of first producing said well at a substantial rate and for asubstantial period of time, whereby there is created in said well a substantial reduction in the bottom-hole pressure below its static value, then rapidly introducing into the well annulus a quantity of conditioningwater calculated to increase said bottom-hole pressure substantially butin a total amount less than the amount of said reduction, continuing the producing of said well and the introduction of said conditioning water, said continuing introduction of water being at a substantial rate but less than said continuingwell-producing rate, until said water has reached the bottom of a test zone in said well and formed in said annulus a column extending at least through said zone, and measuring as a function of depth the electrical conductivity of said conditioning water characterizing its contamination by entering formation water, while producing said well and drawing down said conditioning water column through the well test zone.

5. The method of testing a well which comprises the steps of first producing said well at a normal rate for -a period of time sulicient to reduce the bottom-hole pressure in said well substantially below its static value, then rapidly introducing into the annulus of said well a conditioning liquid miscible with a well liquid to be detected but contrasting therewith in some measurable property, in an amount calculated to increase said bottom-hole pressure substantially but less than the amount of its reduction, continuing the producing of said well and con tinuing the introduction of said conditioning liquid at a substantial fraction of the rate of said continuing producing, until said conditioning liquid approaches the bottom of a test zone in said well, temporarily discontinuing both said well-producing and the introducing of conditioning liquid until said conditioning liquid has consolidated into a column in said well annulus extending at least through said test zone, resuming said producing and said introducing of conditioning liquid at at substantial fraction of lthe rate of said producing, and measuring .as

a function of depth in said well a property of said conditioning liquid characterizing its contamination by rentering formation` fluids, while producing said well and drawing down said conditioning liquid column through the well test zone.

6. The method of testing a well which comprises the steps of first producing said wellat a normal rate and for a suicient period of time to reduce its bottom-hole pressure substantially to a producing equilibrium Value which is substantially less than its static equilibrium value, then rapidly introducing into the well annulus a quantity of a conditioning liquid calculated to increase said bottom-hole pressure by an amount about one-half of its reduction below said static equilibrium value, continuing the producing of said well at said normal rate and the introducing of said conditioning liquid at a reduced rate which is about one-half of said normal producing rate, until said conditioning liquid has reached the bottom of a test zone in said well and formed in the well annulus a column extending at least through said zone, and measuring as a function of depth a property of said conditioning liquid characterizing its contamination by entering formation fluids, while continuing to produce said well and drawing down said conditioning liquid column through the wall test zone.

7. .The method of testing a well which comprises the steps of rst producing said well at al normal rate for a period of time suflicient to create a substantial reduction in bottom-hole pressure under its static value, then rapidly introducing into the well annulus a quantity of conditioning liquid calculated to increase said bottom-hole pressure by substantially one-half the amount of said pressure reduction, continuing the producing of said well. and the intro# ducing of said conditioning liquid, said continuing introducing being at a rate approximately one-half of the well producing rate, until said conditioning liquid has arrived at the bottom'of a test zone in said well, temporarily discontinu-y ing the producing of said well and the introduc-l ing of said conditioning liquid until it forms in the well annulus a consolidated column extending at least through said test zone, resuming the producing of said well, and measuring as a function of depth a property of said conditioning liquid characterizing its contamination by entering formation fluids, while continuing to produce said well and simultaneously drawing said column of conditioning liquid down past said test zone.

8. The method of testing a well which comprises the steps of rst producing said well at a normal rate for a time sufficient to reduce the bottomhole pressure in said well substantially below its static value, introducing into the annulus of said well at a slow rate and over an extended period of time conditioning water miscible with the well water to be determined but contrasting therewith in electrical conductivity, rapidly introducing into saidiwell annulus an additional quantity of said conditioning water calculated to increase the bottom-hole pressure in said well by about one-half the amount of its reduction below the static value, continuing the producing of said well and the introducing of said conditioning water at a reduced rate which is a substantial fraction of said producing rate, until said conditioning water reaches the bottom of a test zone'in said well and forms in the' well annulus a consolidated column extending at least through said test zone, and measuring as a function of depth the conductivity of said conditioning water characterizing. its contamination by entering formation Water, while producing said well and drawing down said conditioning water column through the well test zone.

9. The method of testing a well which comprises the steps of rst producing said well at a normal rate for a period of time to reduce substantially the bottom-hole pressure in said well under its static value, then introducing into the well annulus slowly and over an extended period of time a conditioning liquid miscible with the well liquid to be detected but distinguishable therefrom in s ome measurable property, then rapidly introducing into the well annulus a quantity of said conditioning liquid calculated to increase the bottom-hole pressure by about one-half of the amount of its reduction below said static value, continuing the producing of said well and the introducing of said conditioning 11 liquidY at a rate about one-half of said continuing Well-producing rate, until said conditioning liquid approaches the bottom of a test zone in said well, temporarily discontinuing the producing of said well and the introducing of said liquid until said conditioning liquid forms in the well annulus a consolidated column extending at least through said test zone, resuming the producing of said Well, and measuring repeatedly as a function of depth a property of said conditioning liquid characterizing its contamination by entering well uids, while continuing to produce said well and simultaneously drawing said column of conditioning liquid down past said test zone.

10. The method of testing a well which comprises the steps of rst producing said well at a normal rate for a period of time suflicient to create a substantial reduction in the bottom-hole pressure under its static value, rapidly introducing into the well annulus a quantity of conditioning liquid calculated to increase said bottomhole pressure by about one-half of said reduction, continuing the producing of said Well and the introduction of said conditioning liquid. said continuing liquid introduction being at about onehalf of the continuing well-producing rate, until said conditioning liquid approaches the bottom of a test zone in said well, temporarily discontinuing the producing of said well and the introducing of said conditioning liquid until said liquid forms in the well annulus a consolidated column extending at least through said test zone, resuming the producing of said well at a normal rate but not the introduction of said liquid into the well annulus, and repeatedly measuring as a function of depth a property of saidl conditioning liquid characterizing its contamination by entering formation iluids, while continuing to produce said well and simultaneously lowering the fluid level in the well annulus toward a position of dynamic uid level equilibrium, whereby the formation fluids are produced into said conditioning liquid column at an increasing rate.

11. The method of testing a Well which comprises the steps of producing said well at a normal rate for a period of time suiiicient to create a substantial reduction in the bottom-hole pressure below its static value, then rapidly introducing into the Well annulus a quantity of conditioning liquid calculated to increase Said bottom -hole pressure substantially but less than the amount of said pressure reduction, continuing the producing of said Well and the introducion of said conditioning liquid, said continuing introduction being at a substantial fraction of the well producing rate, until said conditioning liquid approaches the bottom of a test zone in said well,

temporarily discontinuing the producing of said well and said liquid introduction until said liquid forms in the well annulus a consolidated column extending at least through said test zone, and whereby the Well approaches a condition of static equilibrium, resuming the producing of said well, and measuring as a function of depth a property of said conditioning liquid characterizing its contamination by entering formation fluids While said well is passing from near a static toward a producing equilibrium, during the continuous production of formation fluids and the lowering of the liquid column in the well annulus.

12. The method of testing a well to determine the location of Water ingress therein which comprises the steps of rst producing said well at a normal rate for a period of time suicient to. create a substantial reduction in bottom-hole pressure below its static value, then rapidly introducing into the well annulus a quantity of water calculated to increase said bottom-hole pressure by about half the amount of said pressure reduction, continuing the producing of said well and the introduction of said water, said continuing Water introduction being at a rate approximately one-half of the continuing well-producing rate, until said water approaches the bottom of a test zone in said Well, temporarily discontinuing the producing of said well and said water introduction until said water forms in the well annulus a consolidated column extending at least through said test zone, resuming the producing of said well, resuming the introducing of said Water at a rate which is a substantial fraction of said producing rate, and measuring as a function of depth the conductivity of said water characterizing its contamination by entering formation water, while continuing to produce said well and simultaneously drawing down said column of conditioning water past said test zone.

13. The method of testing a Well to determine the location of ingress of fresh water therein comprising the steps of irst producing said well at a normal rate for a period of time suiiicient to create a substantial reduction in bottom-hole pressure below its static value, then rapidly introducing into the well annulus a quantity of salt water calculated to increase said bottom-hole pressure by approximately one-half the amount of said pressure reduction, continuing the producing of said well and the introduction of said salt water, said continuing salt water introduction being at a rate approximately one-half of the well producing rate, until said salt water has arrived at the bottom of a test zone in said well, temporarily discontinuing the producing of said well until said salt water forms in the Well annulus a consolidated column extending at; least through said test zone, resuming the producing of said well and the introduction of said salt water at approximately one-half of the wellproducing rate, and measuring as a function of depth the electrical conductivity of said salt water characterizing its dilution by entering fresh water from the well formations, while continuing to produce said well and simultaneously drawing said column of salt water down past said test zone.

14. The method of testing a well which comprises the steps of rst producing said well at a normal rate for a period of time to reduce the bottom-hole pressure in said Well substantially below its static value, introducing rapidly into the annulus of said well a quantity of conditioning Water calculated to increase said bottomhole pressure by a substantial amount but less than the total amount of reduction of said pressure, continuing the producing of said well and the introducing of said conditioning water at a substantial fraction of said producing rate, until said water approaches the bottom of a test zone in said Well, temporarily discontinuing said well producing and introducing of conditioning water, repeatedly measuring the height of the consolidated column of water in said zone until it is at least as high as the top of said zone, then resuming the producing of said well, resuming the introducing of water at a rate less than the total producing rate of said well and adjusted to maintain a predetermined constant bottom-hole pressure on the well formations, and repeatedly measuring the electrical conductivity of said conditioning Water column until a relatively 13 14 stable pattern of contamination by entering well UNITED STATES PATENTS liquids is obtained, While producing said Well and Number Name Date drawing dwn said conditioning water column 1536,007 Huber Am 2S 1925 through the Well test zone. 555,801 Hubei. Se'p" 292 1925 RALPH@ HARTLHF 1,786,196 Ennis Das, 2s, 1936 ROBERT P- MURPHY 1,865,847 Ennis July :3, 1632 REFERENCES SETE@ The oilowing references are of record in the fue of this patent: l