US2480720A - Method of locating water and gaseous fluid stratas in well bores - Google Patents

Description

Aug. 30, 1949. H. .1. EASTMAN METHOD OF LOCATING WATER AND GASEOUS FLUID STRATAS IN WELL BORES Filed May .8, 1944 Haflan Jolm Easfmcm INV ENTOR fiz/IiJm/A ATTORNEY Patented Aug. 30, 1949 UNITED STATES PATENT OFFICE METHOD OF LOCATING WATER AND GASE- OUS FLUID STRATAS IN WELL BORES Harlan John Eastman, Denver, (3010., assignor to Eastman Oil Well Survey Company, Denver, 0010., a corporation of Delaware Application May 8, 1944, Serial No. 534,680

12 Claims. (Cl. 73-155) i viously because the water, gaseous fluid and oil are thoroughly admixed with each other when brought to the surface, it is impossible to determine at what elevation the water and gaseous fluid entered the fluid column. The ingress of water int the well bore is undesirable and it is necessary to determine the exact point of such ingress in order that a sealing off, by cement or other means, of the water strata may be effected. The gaseous fluid which enters the bore is, because of its pressure, desirable since it aids in flowing the oil into the well bore and for this reason, it is advantageous to know the point of entry of the gaseous fluid into the well bore so that the entry of such fluid will not be restricted when the water strata is sealed off. Various methods of locating the point of ingress of water into a well bore have been devised but all such methods involve the measurement of one or more electrical properties of the fluid column in the well bore.

The salt or saline water which enters the well bore from its strata has a higher temperature than the oil flowing into said bore whereby at the point of entry of the salt water into said bore, a high temperature zone is created. Gas or gaseous fluid on the other hand will expand as it enters the well bore from its strata and such expansion will result in the creation of a cool zone within the bore, this cool zone being located within the well bore opposite the point of entry of the gas or fluid. The present invention contemplates a method wherein these temperature zones are utilized to indicate the location or elevation of the water and gas stratas traversed by the well bore.

For the purpose of this description .the term gas will be used throughout and by this term is meant either gas as it is found in well bores or any hydrocarbon or otherfluid which enters the well bore in a gaseous state.

One object of the invention is to provide a simple and improved method whereby the exact elevation or point of entry of water, as well as gaseous fluid, into a well bore may be positively ajngi accurately determined in a minimum length 0 me.

A particular object of the invention is to pro vide an improved method, of the character described, wherein temperature recording apparatus is lowered through the well fluid column, whereby the natural higher temperature zone created by the entry of water and the cooler temperature zone created by the entry of gas may be accurately located to indicate the point of ingress of such water and gas into said well bore.

Another object of the invention is to provide an improved method of the character described which consists in first artificially changing the normal temperature of the fluid column in the well either by heating or cooling said column, and then taking temperature recordings throughout the fluid column; whereby the hotter zones caused by entry of salt water into the well bore and the cooler zones created by the entry of gas into said bore may be more readily located by means of said temperature measuring apparatus.

A particular object of the invention is to provide an improved method of locating the point of entry of salt water and gas into a well bore which includes the steps of first removing a portion of the normal well fluid column which stands in the well bore, such removal of said portion being from the top of the column so as to prevent disturbance of the remainder of said fluids, then permittin the column to return to its normal level which is caused by the entry of additional fluids from the formations, and then taking continuous temperature readings throughout the column to ascertain the difierent temperature zones created by the entry of salt water and gas into said bore which were caused to flow intothe bore by the first step of lowering of the normal standing liquid level.

Still another object of the invention is to provide an improved method, of the character described, wherein the artificial change of temperature of thefluid column may be utilized in connection with the lowering of the standing liquid level so that the temperature zones created by the entry of the water and gas are more easily detected.

A still further object of the invention is to provide a method which is preferably continuous, that is, the steps thereof, are carried out as rapidly as possible so that the temperature zones which are to be detected are not dissipated before the temperature measurements are made; also, the steps of said method may be repeated as many times as desirable in order to not only locate the point of entry but also to indicate the volume of water or gas entering at such point.

The method contemplates the use of any suitable artificial heating or cooling means and also the use of any suitable continuous temperature recording apparatus.

The construction designed to carry out the invention will be hereinafter described together with other features of the invention.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawing, wherein an example of the invention is shown, and wherein:

Figure 1 is a transverse, vertical sectional view of a' well bore illustrating the various underground stratas traversed by said bore,

Figure 2 is a diagrammatic view, showing a cooling unit being lowered through the column to change its temperature,

Figure 2A is a view similar to Figure 2 and illustrating a heating pipe lowered within the well,

Figure 3 is a diagrammatic view, showing the normal standing fluid level of the well being lowered by means of an ordinary bailer,

Figure is a similar view illustrating the lowering of a temperature measuring apparatus through the fluid column which has risen back to its normal standing level,

Figure 5 is a view of a portion of the temperature recording chart of the measuring apparatus, and

Figure 6 is a view similar to Figure 5 showing another indication on the chart.

In the drawings, the numeral l0 designates a well bore which has the usual well casing H extending downwardly therein. As is the usual practice the lower end of the casing is cemented in place, as indicated by the cement 62. A perforated oil inlet pipe I3 extends downwardly from the casing and the well fluids enter the well bore through the perforation of said pipe, said fluids rising upwardly in the well casing to the normal I This standing standing liquid level of the well. liquid level, indicated at L in the drawings, will of course vary in accordance with particular well conditions.

The various subterranean stratas which are traversed by a well bore are dependent upon the particular area in which said well bore is located and merely for the purpose of illustration, the well bore i!) is shown as having a water strata A behind the well casing It, a second water strata B opposite the inlet pipe IS, a gas strata C also adjacent said pipe and an oil sand or producing formation D at the lower end of the well bore. The water from the strata A will flow downwardly along the outside of the well casing H and cement anchor and will enter the well bore at the lower end of said casing; water from area B and gas from the strata C will flow into the bore at the elevations opposite said area and said strata while the oil will enter at the lower end of the bore opposite the producing formation D. These well fluids will difl'use and admix with each other and will rise to the normal standing level L of the well. The longer said fluids are permitted to stand in the well bore undisturbed, the more diflicult it becomes to determine the point of entry of the various constituents because manifestly, the water will tend to settle downwardly while the gas and oil will tend to rise above the water. Therefore although it is readily apparent that water and gas are present in the fluid column, it is impossible to know at what elevation tsJaicl water and gas originally entered the well ore.

As has been stated, the water which enters a well bore from an underground strata is salt water and it has been proven that this salt water has a higher temperature in situ than oil. From this it follows that when the salt water first enters the well bore it creates a high temperature zone within the bore and immediately adjacent its point of entry. This zone remains within the bore until sufiicient diffusion or admixture of the water with the other well fluids has occurred to bring about an equalization of temperatures.

In contrast to the higher temperature zone created by the entry of salt water into a well fluid column, gas flowing from a subterranean strata into a well bore will expand upon entering said bore, such expansion being caused by the reduction in pressure as the gas enters the bore. This expansion of the incoming gas creates a cooler zone in the bore and manifestly, such zone will be adjacent the point of entry. Until the lapse of suflicient time to permit dissipation of the cooler zone, said zone will be apparent in the fluid column.

In carrying out the present invention, a temperature measuring apparatus i5 is adapted to be lowered through the fluid column on the usual electrical conductor cable 16 (Figure 4).

The apparatus may be of any of the well known types now in use for determining the temperature of well fluids within a bore hole and is capable of continuous recording. The electrical conductor cable 16 has electrical connection with and actuates a surface recording apparatus i! which includes a movable tape 18 and stylus l9 (Figure 5). The stylus is controlled by the measuring apparatus which is lowered through the well fluids and obviously any change in fluid temperature as measured by the measuring apparatus is visibly recorded on the tape by the indicating line 20 made by the stylus.

The apparatus I5 is first lowered through the fluid column and the normal temperature of said column is recorded on the tape. This information indicates the temperature of the fluid column throughout its length under normal dormant conditions and after the diffusion or admixture of all of the constituents making up said column. Ordinarily this temperature will be fairly constant because the various different temperatures of the water, gas and oil have had suificient time to equalize themselves.

After the normal temperature of the fluid column is obtained, the measuring apparatus 15 is withdrawn and a bailer 2| is lowered in the usual manner on a wire line or cable 22. The bailer is employed to remove a portion of the liquid column, such removal being from the upper end of said column whereby the remainder of the column is undisturbed. This bailing operation lowers the level of the fluid column from the point L, its normal level to some point therebelow as indicated by M. Preferably the level is lowered only a few feet but obviously the diameter of the well bore, the height of the normal level and other factors must be considered so that the distance which the normal level is lowered by the bailing operation is actually dependent upon individual well conditions.

When the normal standing level of the fluid column is lowered, the natural function of the column to again seek its normal level will cause additional well fluids to enter the bore. This means that water will enter at the extreme lower end of the casing II and also opposite the strata B while gas will flow into said bore adjacent its strata C. Oil will enter from the formation D at the lower portion of the bore. As explained, the water is of a higher temperature and will create high temperature zones AA and BB at its point of entry whereas the gas will create a cool zone CC at the point adjacent its entry.

As soon as the normal level L of the well is again attained, or even before such level is reached provided'additional water and gas has entered the bore, the temperature measuring apparatus is again lowered through the fluid column. The previous temperature recording apparatus has given the operator the normal temperature of the column and thus so long as the recording apparatus indicates this normal or base temperature, the operator is advised that the apparatus I is moving through the fluid which was present in'the bore upon the previous run. However, as soon as the apparatus l5 enters the higher temperature zone AA, this higher temperature is recorded by an offset 22 in the recording line (Figure'5) thereby indicating the presence of such zone. The recording tape I8 is synchronized with the lowering of the cable I6 so that the exact elevation in feet of the zone AA is indicated. Since the higher temperature zone AA is created by the entrance of salt water into the fluid column the exact point of ingress of the water is thereby determined.

As the apparatus moves downwardly out of the zone AA and into the fluid column, the temperature is again the normal or base temperature and is so indicated by the stylus and tape. Upon entry into the second zone BB, the meas uring apparatus I 5 again actuates the recorder to form a second offset 23 in the indicating line to indicate the presence and location of said zone, whereby the operator is advised that water is entering the well bore at a second elevation. Upon continued lowering of the apparatus, said apparatus passes out of the zone BB and the recorder again indicates the normal or base temperature.

Such indication continues until the apparatus l5 moves into the cool zone CC at which time the cooler temperature is recorded by an offset 24 in the recording line on the tape l8. The offset 24 is opposite to the ofisets 22 and 23 since the zone CC is cooler, rather than hotter, than the normal temperature as represented by the recording line. It is known that a cooler zone is created by the entrance of gas and thus the location of the gas strata C is determined. After passing through the zone CO, the continued lowering of the apparatus I5 to. bottom will indicate no other temperature zones since the contents of the remainder of the bore consists only of some additional oil which was caused to enter when the normal level was lowered.

From the above it will be seen that a simple and accurate method of determining the location of water and gas stratas is had. The exact point of entry of the water and gas is ascertained and when water is shown as entering at the lower end of the well casing, as illustrated in Figure 1, it is known that either there is a water strata at this point or the water is seepingdownwardly from a strata behind the casing. By accurately locating the point of entry of the water, such entry can be prevented through the usual cementing procedure. The location of the point of entry of the gas is also important because in most cases the gas is adjacent the oil producing formation. There are instances where the gas is also adjacent a water formation and in attempting to seal ofl the water, the gas and oil sands have also been unintentionally sealed off. By knowing exactlywhere the gas enters the bore, care can be taken to assure scaling 011 the water to prevent its entry without danger of also sealing oil. the gas formation. Thus, the method herein not only locates the point of entry of water but also locates the point of ingress of the gas and this is an important feature of the invention.

After the temperature measuring run is made to locate the elevations at which the water and gas is entering the bore, the bailer 2| may again be used to again lower the level of the fluid column whereby additional water, gas and oil may flow into the column. The temperature measuring apparatus is then again lowered through the fluid column and the recordings made thereby noted. It is pointed out that by the time the apparatus reaches the zones AA, BB and CC, these zones have expanded or diffused outwardly in the fluid column due to additional entry of water and gas. The diffusion or expansion of such zones indicates the volume of flow of water and gas into the bore and this is recorded on the tape Hi. This recording is shown in Figure 6, the offsets 22a, 23a and 24a representing the zones AA, BB and CC respectively. It is noted that the offset 23a is of greater area than the offset 22a thereby indicating that .the zone BB was of greater area than the zone AA. The

increased area of zone BB was caused by a greater volume of water entering the bore from the strata B than the water entering zone AA from strata A. Thus, the second run of the measuring apparatus will indicate the volume or rate of how of the water and gas into the bore at the various elevations.

It is apparent that the bailing operation followed by the lowering of the temperature measuring apparatus may be carried out as many successive times as desirable. Ordinarily three or four runs are ample, although in many cases one or two runs may provide sufiicient definite information. In all cases, the particular well conditions will control.

There may be instances, particularly in high temperature wells where it may be difficult to locate the zones AA and BB created by the entry of the salt water; in-other low temperature wells location of the gas zone CC may be hard to discern because of the lack of sufiicient temperature difierenc between the zone and the normal temperature of the fluid column. When temperature conditions in the well bore are such as to make the determination of the location of the zones AA, BB, and CC clifiicult, an auxiliary step is added to the method.

In the location of the high temperature zones, a cooling unit 25 (Figure 2) is first lowered through the well fluid column in order to cool said column to a desired temperature which is known to be below the temperature of the incoming salt water. This cooling unit may be an elongate container containing carbon dioxide or Dry Ice as it is commercially called. This container is lowered slowly through the column and may have to be raised and lowered several times in order to obtain the desired lower temperature.

After the column is cooled, the temperature of the column is recorded to establish a normal or base temperature. A bailing operation, as has been described, is then carried out followed by another run of the measuring apparatus. It will be apparent that by first cooling the column by artificial means, a greater temperature differential will be set up between the zones AA and BB and the fluid column, whereby said zones are more easily detected and more accurately located. Of course as has been pointed out, any desired number of subsequent bailing operations and measuring apparatus runs may be made.

The COOIii'lg of the fluid column may be controlled so that the zone CC will be of a lower temperature than the artificial zone so created so that the zone CC will also be indicated. In such event, the gas zone CC is determined at the same time as the water zones are located.

If the normal temperature of the fluid column is low thereby making the gas zone difficult to locate, said column may be heated to accentuate a temperature difference between the gas zone and the fluid. Such heating step may be carried out by lowering a small pipe 26 within the well bore (Figure 2A) and introducing steam or hot water into the liquid column. When the column has been heated to the desired temperature, the

bailing operations and measuring apparatus runs, as herein before described, are made to locate the zones AA, BB and CC.

From the foregoing, it will be seen that a simple and accurate method of locating the point of entry of both water and gas into a well bore is provided. It is only necessary to lower the level of the fluid column to permit entry of additional well fluids and then make temperature measurements. Successive measurements make it possible to not only locate the water and gas stratas but to also determine the rate of flow or volume of the water and gas entering the bore. The use of artificial heating or cooling means to produce a resired temperature in the fluid column sets up an increased temperature differential between the zones created by the water and gas and the fluid column, whereby said zones are more easily and more accurately located.

The foregoing description, of the invention is explanatory thereof and various types of temperature recording, bailing, heating and cooling apparatuses may be employed to practice the method, within the scope of the appended claims, without departing from the spirit of the invention.

What I claim and desire to secure by Letters Patent is:

l. The method of locating the point of entry of water and gaseous fluids into a well bore which includes, determining the temperature of the well fluid column which is formed by the flow of fluids into the well bore from the formation and which normally stands in the well, then removing well fluids from the upper portion of said column to permit additional well fluids to enter said bore, and then determining the temperature of the well fluid column along the entire length of said column after the entry of said additional fluids to locate the different temperature zones created by the entry of water and gaseous fluids whereby the location of the point of the entry as indicated by said zones may be ascertained.

2. The method as set forth in claim 1, with the subsequent step of removing additional fluid from the upper end of the column, and then again determining the temperature of said column to ascertain the diffusion and increase of the temperature zones created by the incoming water and gas, whereby the volume of water and gas entering the bore may be determined.

3. The method of locating the point of entry of water and gaseous fluids into a well bore which includes, artificially changing the normal temperature of the well fluid column which has entered said bore from the formation and which normally stands in the well bore to impart a known temperature to said column, then removing a portion of the fluids from the upper end of said column to permit entry of additional well fluids from their respective stratas, and then measuring the temperature of the column throughout its entire length to locate the high and low temperature zones created by the entry of water and gaseous fluids respectively, which zones are adjacent the point of entry of said water and gaseous fluids.

4. The method as set forth in claim 3, with the subsequent steps of again removing additional well fluids from the upper portion of the fluid column to admit more well fluids into the bore, and then again measurin the temperature of the fluid column to determine the extent of the expansion of the water and gaseous fluid temperature zones, which expansion is indicative of the volume of water and gaseous fluids entering said bore.

5. The method as set forth in claim 3, wherein the artificial temperature changing step is a cooling of the well fluid column so that the hotter temperature zone created by the entry of water into the bore may be more readily and accurately detected.

6. The method as set forth in claim 3, wherein the artificial temperature changing step is a heating of the well fluid column so that the cooler temperature zone created by the entry of gaseous fluid into the bore may be more readily and accurately detected.

'7. The method as set forth in claim 3, with the subsequent steps of removing fluid from the upper portion of the column, and then again measuring the temperature of said column, said subsequent steps being alternated and repeated a plurality of times to assure accurate deter mination of the elevation of the various temperature zones created by the entry of water and gaseous fluids and also to determine the extent of the diflusion or expansion of each zone to ascertain the volume of water and gas entering said bore.

8. The method of locating water and gas within a well bore which includes, measuring the temperature of the well fluid column which has entered the well bore from the formation and which normally stands in the well bore to determine the norma temperature of said column throughout its length, bailing a portion of the well fluids from the bore to lower the level of the column and thereby cause the entry of additional well fluids into the bore, and then again measuring the temperature of said column throughout its entire length after such additional fluids have entered the same to locate the elevation of the diflerent temperature zones created by the entry of water and gaseous fluid into the bore, which zones are adjacent the point of entry of said water and gaseous fluid.

the subsequent steps of alternately bailing to remove additional fluid from the column and measuring the temperature of said column to determine the extent of diffusion or expansion of the temperature zones created by the admitted water and gas, whereby the volume of water and gas entering the bore may be determined.

11. The method of locating the point of entry of water into a well bore which includes, determining the temperature of the well fluid column which is formed by the flow of fluids into the well bore 'from the formation and which normally stands in the well, then removing well fluids from the upper portion of said column to permit additional well fluids to enter said bore, and then determining the temperature of the well fluid column along the entire length of said 'column after the entry of said additional well fluids to locate the temperature zone created by the entry of water into the bore, whereby the location of the point of entry of the water as indicated by said zone may be ascertained.

12. The method of locating the point of entry of water into a well bore which includes, artificially changing the normal temperature of the well fluid column which has entered said bore from the formation and which normally stands REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,290,075 Schlumberger July 14, 1942 2,301,326 Reistle Nov. 10, 1942- 2,366,694 -Bender Jan. 9, 1045 FOREIGN PATENTS Number Country Date France NOV. 16, 1933

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