US2868625A

US2868625A - Method of tracing the flow of water

Info

Publication number: US2868625A
Application number: US523944A
Authority: US
Inventors: Wallace J Frank
Original assignee: Jersey Production Research Co
Current assignee: Jersey Production Research Co
Priority date: 1955-07-22
Filing date: 1955-07-22
Publication date: 1959-01-13
Anticipated expiration: 1976-01-13

Description

ETHYLENEDIAMINE TETRAACETIC ACID (PARTS PER MILLION) Jan. 13, 1959' w. J. FRANK 2,868,625 METHOD OF TRACING THE FLOW OF WATER Filed July 22, 1955 C-ALIBRATION CURVE FOR DETERMINATION F ETHYLENEDIAMINE TETRAACETIC ACID BY I THE NICKEL DITHIO- OXALATE METHOD 0 2o 40 so so I00 I I I I COLORIMETER READING (CHART DIVISIONS) INVENTOR. WALLACE J. FRANK,

United States Patent METHOD OF TRACING THE FLOW OF WATER Wallace J. Frank, Houston, Tex., assignor, by mesne assignments, to Jersey Production Research Company, Tulsa, Okla., a corporation of Delaware Application July 22, 1955, Serial No. 523,944

7 Claims. (Cl. 23-230) The present invention relates to tracing the flow of waters. More particularly, the present invention is directed to tracing the flow of water during its passage underground from a first point to a second point. In its more specific aspects, the invention is directed to tracing the flow of water used in water flooding operations in oil and gas fields from which hydrocarbons are produced.

For the last 25 years, many chemicals have been used as a tracer in water, in water production, and in water flooding in oil and gas fields. Tracers have also been used in detecting the flow of water in oil and gas wells, particularly where leakages may occur through a casing or around a packer. Inorganic chemicals have been used in many instances to trace flow of water in wells and particularly water movement between a well drilled to kill a blowout and the blowout well. The inorganic chemicals used heretofore have been objectionable because of the difliculty in detecting small concentrations particularly in cases where particular materials may be native to the water being traced. In many instances, inorganic chemicals have been naturally occurring and frequently obscured the arrival of the water containing the trace inorganic compounds.

Organic materials have been inefiective because they are readily adsorbed by argillaceous and other materials in the earth formation through which the water flows or with which the water comes into contact.

It has now been discovered that ethylene-diamine tetra acetic acid and its water soluble salts, such as sodium, potassium, and lithium salts as well as the calcium, magnesium, barium, strontium, nickel, copper,-iron, lead, cadmium, zinc, cobalt, aluminum, chromium and the like, salts, may be added to the water, the flow of which is bc-. ing traced either in a stream or througha pipe line, an oil or gas well conduit, or through an underground formation. When a salt is used the sodium salt is preferred. Ethylene-diamine tetra acetic acid is available on the market and is known to the trade as Versene or Tetrine. The Versenes are available from the Bersworth Chemical Co., Framingham, Massachusetts. The compound may be added as a liquid or as a solid directly .to the water, the flow of which is to be determined.

The amount of the ethylenediamine tetra acetic acid or its water soluble salts may be as little as 1 part per million in the water but usually an amount sufficient to provide parts per million may be desirable. Higher concentrations up to 50 parts per million may be used but ordinarily it will be desirable to employ an amount in the range from about 3 to about 15 parts per million; at the lower concentrations, the detection of the water is quantitative whereas in concentrations of at least 5 parts per million the detection is qualitative. The invention may thereafter be used for both the determination of qualitative and quantitative flow. The arrival of the water from a first point to a second point remote from the other methods of tests may readily be used. In a test water, such as salt water containing ethylenediamine tetra acetic acid or the sodium salt thereof, which is preferred, the water may be flowed from a first point to a second point remote from the first point, samples of about 200 cc. of the water containing the compound may be demineralized by passing same through an anion-cation demineralizer to remove any naturally containing salts, if desired. Passage of the salt water containing the ethylenediamine tetra acetic acid or its salt has no detectable effect on the concentration of the ethylenediamine tetra acetic acid in the water. 100 cc. of the demineralized water is then adjusted to a pH of about 6.5 to which is added approximately 5 cc. of ammonium hydroxide followed by the addition of 10 cc. of nickel sulfate solution. After standing for 10 minutes, 15 cc. of 1.5% dimethylglyoxime is added while stirring. This solution, after standing for 10 minutes, is filtered to remove excess nickel which has not reacted with the ethylenediamine tetra acetic acid. The acid is soluble to a suflicient extent in water for use as a tracing agent. The method of test employed is based on the fact that nickel is selectively sequestered by the ethylenediamine tetra acetic acid.

To an aliquot of the filtrate, hydrochloric acid is added to lower the pH to l, and then 10 cc. of 0.25 weight percent solution of potassium dithio-oxalate is added to give a red color. This color develops because of the reaction between the nickel and potassium dithio-oxalate. The intensity of the color is then measured in a spectrophotometer at a wave lentgh of 508 millimicrons. A calibration curve using distilled water containing various concentrations of ethylenediamine tetra acetic acid was obtained in the foregoing manner. The results of these tests presented in the single figure of the drawing show that the concentration of ethylenediamine tetra acetic acid plotted against the percent of light transmittance at a wave length of 508 millimicrons gave a straight-line relationship. This allows the determination of the concentration of the compound in the water.

In an oil field in which a number of oil wells have been drilled and oil has been produced from these wells over a number of years there finally arrives a time when oil no longer flows into the well in sufficient quantity to be recoverable from an economic standpoint. When such conditions are finally present it is often economically possible to force a liquid such as water down some of the wells to flood the formation which still contains perhaps of the oil it originally contained. Depending upon formation structure, such as differences in permeability caused by fractures or more porous portions, the water flooding the formation will force oil and other water ahead of it into certain of the oil wells from which they may be recovered. A greater or less amount of the oil remaining in the formation is thereby recovered and the percentage that is recoverable depends largely upon the proper selection of the water input wells and the amount of water forced into them. The more that the operator knows about what conditions are underground the more intelligently he can control the operation and in turn the more oil will be recovered.

At the output wells the oil and water being produced can be separated and the water tested to determine whether it is connate water or whether it is input water used in the waterflood if a tracing agent of a satisfactory nature has been placed in the input water used for the waterflood.

In practicing the present method, the ethylenediamine tetra acetic acid or its water soluble salts is added to the injection water in a sutficient quantity to give preferably the concentration of from about 3 to about 15 parts per million of the compound in the water. There is no difficulty in the amount of the compound which may Patented Jan. 13, 1959 be used because ethylenediamine tetra acetic acid and its water soluble salts are not naturally occurring and do not exist naturally in flowing waters whether they be in a stream at the surface. of the earth or flowing underground. Usually 5 parts per million will give desirable results in water flood operations.

The water is added to the injection water at the input well in a water flooding operation and production of oil and/or gas or water occurs in the output wells where the Water produced is separated from the oil produced and collected at regular intervals from selected wells for analysis such as by the method indicated but not limited thereto. This makes it possible to follow the arrival of the water at the several production Wells from the injection well and allows the operator to determine whether or not the water is travelling to a particular production well.

The present invention is of considerable importance in following the flow of water. Since the ethylenediamine tetra acetic acid and its compounds are unique in that they do not occur in nature and will not be adsorbed byearth formations and will not be lost if it comes into contact with earth formations or if it moves through a subsurface earth formation.

The present invention is particularly applicable to water flooding operations either to initiate recovery of oil and/or gas from a subsurface earth structure or in secondary recovery of oil.

The nature and objects of the present invention having been completely described and illustrated, what I wish to claim as new and useful and to secure by Letters Patent is:

1. The method of tracing the flow of a stream of water which comprises adding to said water at a first point a suificient amount within the range of about 3 to about parts per million parts of Water of a compound selected from the group consisting of ethylenediamine tetra acetic acid and its water soluble salts for detection of said compound, taking samples of said water at a second point remote from the first point and testing said samples for the presence of the organic radical of said compound whereby the presence of said organic radical indicates the arrival of said water containing said compound at said second point.

2. The method of tracing the flow of water underground which comprises adding to said water at a first point a suificient amount within the range of about 3 to about 15 parts per million parts of water of a compound selected from the group consisting of ethylenediamine tetra acetic acid and its water soluble salts for detection of said compound, taking samples of said water at 4 a second point remote from said first point after flow of said water underground and testing said samples for the presence of the organic radical of said compound whereby the flow of said water from said first point underground to said second point is determined.

3. A method of tracing the flow of water underground which comprises adding to said water flowing underground a suflicient amount within the range of about 3 to about 15 parts per million parts of water of a compound selected from the group consisting of ethylenediamine tetra acetic acid and its water soluble salts, taking samples of said water at a second point remote from said first point after the flow of said water underground, and testing said samples for the presence of the organic radical of said compound whereby the flow of said water from the first point to the second point is determined.

4. A method of water flooding a field from which hydrocarbons are produced and tracing the progress of water used in said flooding in which water is forced down an input Well to force liquid out of at least one production well which comprises the steps of adding to said flooding water a sufficient amount within the range of about 3 to about 15 parts per million parts of water of a compound selected from the group consisting of ethylenediamine tetra acetic acid and its water soluble salts taking samples of water from one production well and testing said samples of water for the presence of the organic radical of said compound whereby the arrival of said flooding water at said production Well is determined.

5. A method in accordance with claim 4 in which the compound is ethylenediamine tetra acetic acid.

6. A method in accordance with claim 4 in which the compound is a sodium salt of ethylenediamine tetra acetic acid.

7. A method in accordance with claim 4 in which the amount of the compound is suflicient to provide approximately 5 parts per million of the compound in the flooding water.

References Cited in the file of this patent UNITED STATES PATENTS 2,578,500 Bernard et al Dec. 11, 1951 2,589,219 Bond et al Mar 18, 1952 2,660,887 Frei Dec. 1, 1953 2,696,468 Fisher Dec. 7, 1954 OTHER REFERENCES Martell: Chem. of the Metal Chelate Comp, page i

Claims

1. THE METHOD OF TRACING THE FLOW OF A STREAM OF WATER WHICH COMPRISES ADDING TO SAID WATER AT A FIRST POINT A SUFFICIENT AMOUNT WITHIN THE RANGE OF ABOUT 3 TO ABOUT 15 PARTS PER MILLION PARTS OF WATER OF A COMPOUND SELECTED FROM THE GROUP CONSISTING OF ETHYLENEDIAMINE TETRA ACETIC ACID AND ITS WATER SOLUBLE SALTS FOR DETECTION OF SAID COMPOUND, TAKING SAMPLES OF SAID WATER AT A SECOND POINT REMOTE FROM THE FIRST POINT AND TESTING SAID SAMPLES FOR THE PRESENCE OF THE ORGANIC RADICAL OF SAID COMPOUND WHEREBY THE PRESENCE OF SAID ORGANIC RADICAL INDICATES THE ARRIVAL OF SAID WATER CONTAINING SAID COMPOUND AT SAID SECOND POINT.