GB2238488A - Measuring ion exchange capacity - Google Patents
Measuring ion exchange capacity Download PDFInfo
- Publication number
- GB2238488A GB2238488A GB9026265A GB9026265A GB2238488A GB 2238488 A GB2238488 A GB 2238488A GB 9026265 A GB9026265 A GB 9026265A GB 9026265 A GB9026265 A GB 9026265A GB 2238488 A GB2238488 A GB 2238488A
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- Prior art keywords
- measuring
- exchange capacity
- ion exchange
- ions
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J47/00—Ion-exchange processes in general; Apparatus therefor
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/24—Earth materials
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- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Analytical Chemistry (AREA)
- Geology (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Food Science & Technology (AREA)
- Medicinal Chemistry (AREA)
- Environmental & Geological Engineering (AREA)
- Remote Sensing (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
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- Chemical Kinetics & Catalysis (AREA)
- Sampling And Sample Adjustment (AREA)
Abstract
Apparatus for measuring ion exchange capacity of a material e.g. a geological sample comprises a Hassler tube 1 and a fluid applicator 2 from an HPLC pump 3. The material may be in the form of a sample core plug 4 supported by the tube 1 and is fed solvent containing cations in a soluble form from the pump 3. The first exchange stage replaces all exchangeable cations from the cation exchange sites with Fe<3+> cations. Then the Fe<3+> cations stripped from the exchange site, are collected in a volumetric flask. This is done by treating the plug with a solvent solution containing Na<+> ions. The quantity of Fe<3+> ions recovered is determined by standard analytical procedures and the mass and porosity of the plug are measured used to calculate the cation exchange capacity (CEC). It is preferred the solvents used are methanol, dichloromethane and a combination of the two. <IMAGE>
Description
"Apparatus for use in and method for measuring ion exchanae capacity"
This invention relates to a method of measuring ion exchange capacity particularly on material taken as a geological sample.
It is often necessary to measure the water content of a rock formation in order to obtain an indication of its oil content. For this purpose a resistivity measurement is taken. However, this measurement may be affected by the position of other ions in the material, particularly cations. To determine the extent of this effect the cation exchange capacity (CEC) is measured.
The conventional 'wet' chemical method of measuring the cation exchange capacity of core material requires that the core is crushed. The physical process of crushing leads to the creation of new cation exchange sites, thereby reducing the accuracy with which the analysis can be performed.
According to the present invention there is provided a method of measuring the ion exchange capacity of a material, comprising applying a fluid to the material, substituting ions in the fluid for ions in the material, and calculating the amount of substituted ions, without physically disrupting the structure of the material.
Further according to the present invention there is provided apparatus for measuring the ion exchange capacity of a material, comprising means for holding the material, means for applying fluid to the material and means for measuring the amount of ions in the fluid which have replaced ions in the material.
Preferably the material is core material, a sample of which is taken in the form of a plug.
Preferably the fluid is applied to the plug under pressure.
Preferably the method is carried out using a HPLC pump to apply the fluid and the plug is confined under pressure in a Hassler tube.
Preferably the fluid comprises an organic solvent, most preferably methanol and/or dichloromethane.
Preferably the solvent comprises cations. Preferably said cations are provided as organic salts. However other agents such as chelating agents may be used to provide cations.
Preferably a first solvent is applied to the sample followed by a second solvent. Said first solvent preferably comprises ferric (Fe3+) ions and said second solvent preferably comprises sodium (Na+) ions.
Preferably the amount of substituted ions is calculated by measuring the amount of ions from the first solvent which replaced them.
Preferably the holding means is a Hassler tube.
Preferably a pressure regulator is provided to ensure that the flow of fluid through the plug is as even as possible.
The method of the present invention will now be described by way of example with reference to the single figure which is a sectional view of apparatus for measuring ion exchange according to the present invention. Experimental details are given in the
Appendix.
Apparatus for measuring the ion exchange capacity of a material comprises a holding means in the form of a
Hassler tube 1, a fluid applicator in the form of a conduit 2 from an HPLC pump 3 and measuring means provided as a measuring cylinder or volumetric flask (not shown) into which the fluid can flow as shown at 3 and which is then subjected to standard analytical techniques. The material is provided as a sample core plug 4 and is supported by the Hassler tube under a confining pressure shown at 5.
The solvent which contains cations in a soluble form is fed from the pump 3 through the plug 4 under pressure regulator (not Shown) before going on to be measured for cation content. The exchangeable cations in the plug (eg Na+, K+, Mg2+, Ca2+, etc) are first replaced with a suitable metal cation Mn+. Next, all the excess Mn+ cations are removed by solvent flushing, from the pore spaces within the plug. The plug is then treated with a solvent solution containing Na+ ions, this enables the Mn+ cations to be stripped from the exchange sites, at which point they are collected in a volumetric flask. The quantity of Mn+ cations recovered after stripping is determined by standard analytical procedures.Finally, the mass and porosity of the plug are measured, and used to calculate the CEC and Qv ( the cation exchange capacity per unit pore volume) values.
1. Choice of replacement cations There are two separate stages at which the plug is subjected to cation exchange.
(a) The first exchange stage results in the
removal of all the indigenous cations from the
cation exchange sites and their simultaneous
replacement by another cation Mn+.
(b) The second exchange stage has the function of
recovering all the Mn+ cations (those occupying
the exchange sites) and for this purpose Na+ are
used to effect the exchange.
For the first exchange stage, the ferric (Fe3+) ion has been found to have many desirable features as the Mn+ ion. It does not for instance react with the stainless steel used in the construction of the HPLC pump, pressure apparatus and pipe work, unlike more electropositive cations such as Cu2+, Co2+ and Ni2+.
Another useful feature of working with the ferric ion is the low concentrations to which it can be detected with a visible spectrophotometer, this simplifies the analysis and assists in observing visually the progress of the exchange reaction. Although the Fe3+ ion is recommended, many other cations could be used in its place. Sodium ions are preferred for the second exchange stage since they help to restore the plug back to its original condition, however, other cations or mixtures of cations could be used instead of sodium.
2. Choice of cation 'exchange' extractants
In order to work under non-aqueous conditions it is necessary to use a cation extractant such as an organic acid, which is capable of ensuring that all cations are soluble in the organic solvents to be used. For the current work, a phosphoric acid, di(2-ethylhexyl) phosphoric acid is used. However, a variety of other reagents such as phosphonic acids, phosphinic acids, sulphonic acids, carboxylic acids and various chelating reagents, might be used provided their solubility characteristics are suitable and no undesirable side reactions occur.
3. Solvent treatment
It is advantageous to perform the method of the present invention under non-aqueous conditions since this avoids any problems that might arise from clay expansion. The clays will swell under conditions of low ion activity and/or high pH values. This results in a reduction in the permeability of the plug which consequently increases the time it takes to perform the analysis.
The solvents used by preference are methanol and dichloromethane, together with combinations of these two solvents.
Modifications and improvements may be incorporated without departing from the scope of the invention.
APPENDIX
EXPERIMENTAL DETAILS a) Preparation of reagents
The two reagents iron (III) di(2-ethylhexyl)phosphate and sodium di(2-ethylhexyl)phosphate, used in the analysis are prepared by solvent extraction.
(i) Iron (III) di(2-ethylhexylBphosphate in a dichloromethane/methanol mixture
This is prepared by dissolving 129.0g of di(2-ethylhexyl)phosphoric acid in approximately 350cm3 of dichloromethane, and then pouring the mixture into a 1 litre separatory funnel. A solution containing 60g of ferrous sulphate heptahydrate (FeS04.7H20) dissolved in 300cm3 of distilled water is also prepared and added to the contents of the separatory funnel. A further solution containing 17.5g of sodium hydroxide dissolved in approximately 50cm3 of distilled water is then added portion-wise to the contents of the separatory funnel.
It may not be necessary to add all the sodium hydroxide solution. After each addition of sodium hydroxide the contents of the flask are thoroughly shaken for about 2 minutes and then allowed to stand at room temperature until the two liquid phases disengage. Additions of sodium hydroxide are continued until about 0.5g of permanent precipitate (iron hydroxide) is formed, in the aqueous phase, which should occur after the addition of 17.1 to 17.3g of sodium hydroxide. The formation of a permanent precipitate indicates that no more iron can be extracted into the organic phase. At this point the contents of the separatory funnel are allowed to stand for 30 minutes prior to isolating and filtering the lower (organic) layer. The filtered solvent solution is then made up to 1 litre with dichloromethane.Finally, 1 litre of methanol is added slowly with stirring; care must be exercised at this stage in order to avoid any precipitation of the complexed iron. Provided no precipitation occurs the iron (III) di(2-ethylhexyl)phosphate solution is suitable for use in the cation exchange analysis.
(ii) Sodium di(2-ethylhexyl)shosphate in dichloromethane
This solution is prepared by dissolving lOOg of di(2-ethylhexyl)phosphoric acid in approximately 350cm3 of dichloromethane, and pouring the mixture into a 1 litre separatory funnel. To the separatory funnel is then added an aqueous solution containing 12.5g of sodium hydroxide, 50g of sodium chloride and 400cm3 of distilled water. The mixture is shaken thoroughly for at least 2 minutes and allowed to stand, preferably at 20-250C, for at least 2 hours to 'allow the two liquid phases to completely disengage. The lower (organic) phase is isolated, filtered and then made up to a total volume of 2 litres with dichloromethane.
b) Analysis of CEC of core material
The plugs are first cleaned to remove oil and brine.
They can either be soxhlet cleaned (ideally cold soxhlet cleaned) with conventional solvents or cleaned using a rapid cleaner. In both cases it is important to remove all traces of salt.
The plug to be analysed is placed in a core holder fitted with a Hassler tube. A confining pressure of between 800 - 1500psi is applied. For most plugs a confining pressure of 800 - lOOOpsi is adequate but for plugs with low permeabilities (below 0.7mD), higher confining pressures may be required. To ensure that the flow of solvent through the plug is as even as possible (particularly important with horizontal plugs) a back-pressure regulator is used. A pressure setting of 500psi is normally adequate for the back-pressure regulator.
Using a HPLC pump, a series of solvents/solvent solutions are then passed through the plug. It is advisable to ensure that the solvents are first degassed and that the temperature at which the cation exchange occurs is in the region 18-25 0C. Addition rates throughout the analysis are maintained at 1.5cm3/min (this addition rate should not be exceeded when adding the iron complex).The quantities of solvents and the order of addition are as follows: (i) Methanol 40cm3 (ii) 50/50 (vol/vol) mixture of
methanol and dichloromethane 40cm3 (iii) Iron (III) di(2-ethylhexyl)
phosphate dissolved in methanol/
dichloromethane 160cm3 (iv) 50/50 (vol/vol) mixture of methanol
and dichloromethane 120cm3 (v) Dichloromethane 200cm3 (vi) Sodium di ( 2-ethylhexyl ) phosphate dissolved in dichloromethane 120cm3 (vii) Dichloromethane 40cm3 (viii) 50/50 (vol/vol) mixture of methanol
and dichloromethane 30cm3 During stages (vi), (vii) and (viii), the eluted solvent is collected in a 250cm3 volumetric flask, containing 2cm3 of acetylacetone.The recovered ferric ions generally form an orange-red complex with the acetylacetone, though the colour may vary from yellow to dark red depending on the concentration of ferric ions present. Upon completing the final addition stage (viii), the contents of the volumetric flask are made up to a total volume of 250cm3 with methanol, this solution is referred to as Solution A. Using a pipette, 10cm3 of Solution A together with 4cm3 of acetylacetone are added to a 50cm3 volumetric flask and then made up to volume with a 50/50 (vol/vol) mixture of methanol and dichloromethane, this is Solution B.
The absorption of Solution B is then determined, in a lcm cell, at the maximum absorption occurring in the region of 435 - 438nm. The concentration of iron present can then be calculated from a calibration curve prepared using standard solutions.
The plug is further cleaned to remove all traces of sodium di(2-ethylhexyl)phosphate and is then dried at 1050C for 24 hours prior to determining its mass and helium porosity. Finally, the cation exchange capacity and Qv values are determined.
The procedure outlined above describes the additions required to treat a plug of diameter 1" by 1 - 1.5" in length. For plugs of other sizes it may be necessary to make adjustments to both addition times and to the quantity of solvents used.
Claims (12)
1. A method of measuring the ion exchange capacity of a material, comprising applying a fluid to the material so as to substitute ions in the fluid for ions in the material, and calculating the amount of substituted ions, without physically disrupting the structure of the material.
2. A method of measuring the ion exchange capacity of a material as claimed in Claim 1, wherein the material is a downhole core material, a sample of which is taken in the form of a plug.
3. A method of measuring the ion exchange capacity of a material as claimed in Claim 1 or 2, wherein the fluid is applied to the material under pressure.
4. A method of measuring the ion exchange capacity of a material as claimed in any one of the preceding
Claims, wherein the method is carried out using a pump to apply the fluid and the material is confined under pressure in a Hassler tube.
5. A method of measuring the ion exchange capacity of a material as claimed in any one of the previous
Claims, wherein the fluid comprises an organic solvent.
6. A method of measuring the ion exchange capacity of a material as claimed in Claim 5, wherein the organic solvent is methanol or dichloromethane.
7. A method of measuring the ion exchange capacity of a material as claimed in Claim 5 or 6, wherein the solvent is provided in the form of an organic salt or chelating agent.
8. A method of measuring the ion exchange capacity of a material as claimed in Claim 7, wherein a first solvent is applied to the sample followed by a second solvent, said first solvent comprising ferric (Fe3+) ions and said second solvent comprising sodium (Na+) ions.
9. A method of measuring the ion exchange capacity of a material as claimed in Claim 8, wherein the amount of substituted ions is calculated by measuring the amount of ions from the first solvent which replaced them.
10. Apparatus for measuring the ion exchange capacity of a material, comprising means for holding the material, means for applying the fluid to the material and means for measuring the amount of ions in the fluid which have replaced ions in the material.
11. A method of measuring the ion exchange capacity of a material substantially as hereinbefore described, with reference to the accompanying examples.
12. Apparatus for use in a method of measuring the ion exchange capacity of a mixture substantially as hereinbefore described, with reference to the accompanying examples.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9026265A GB2238488A (en) | 1989-12-02 | 1990-12-03 | Measuring ion exchange capacity |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB898927299A GB8927299D0 (en) | 1989-12-02 | 1989-12-02 | Apparatus for use in and method for measuring ion exchange capacity |
| GB9026265A GB2238488A (en) | 1989-12-02 | 1990-12-03 | Measuring ion exchange capacity |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9026265D0 GB9026265D0 (en) | 1991-01-16 |
| GB2238488A true GB2238488A (en) | 1991-06-05 |
Family
ID=26296298
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9026265A Withdrawn GB2238488A (en) | 1989-12-02 | 1990-12-03 | Measuring ion exchange capacity |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2238488A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2711801A1 (en) * | 1993-10-29 | 1995-05-05 | Elf Aquitaine | Method for measuring the cationic exchange capacity of clays by percolation |
| CN105223306A (en) * | 2015-09-25 | 2016-01-06 | 国网山东省电力公司电力科学研究院 | A kind of device measuring Hydrogen weak-acid cation-exchange resin CEC |
| WO2021221692A1 (en) * | 2020-04-27 | 2021-11-04 | Saudi Arabian Oil Company | Methods of determining cation exchange sites occuped by crude oil and the wettability of cation exchange sites in rock core samples in a non-preserved state |
| WO2021221693A1 (en) * | 2020-04-27 | 2021-11-04 | Saudi Arabian Oil Company | Methods of determining cation exchange sites in rock core samples |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2202047A (en) * | 1987-03-09 | 1988-09-14 | Forex Neptune Sa | Monitoring drilling mud |
| GB2226135A (en) * | 1988-12-15 | 1990-06-20 | Forex Neptune Sa | Monitoring ions present in drilling muds or fluids |
-
1990
- 1990-12-03 GB GB9026265A patent/GB2238488A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2202047A (en) * | 1987-03-09 | 1988-09-14 | Forex Neptune Sa | Monitoring drilling mud |
| GB2226135A (en) * | 1988-12-15 | 1990-06-20 | Forex Neptune Sa | Monitoring ions present in drilling muds or fluids |
Non-Patent Citations (1)
| Title |
|---|
| JP-A-61258165 * |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2711801A1 (en) * | 1993-10-29 | 1995-05-05 | Elf Aquitaine | Method for measuring the cationic exchange capacity of clays by percolation |
| CN105223306A (en) * | 2015-09-25 | 2016-01-06 | 国网山东省电力公司电力科学研究院 | A kind of device measuring Hydrogen weak-acid cation-exchange resin CEC |
| WO2021221692A1 (en) * | 2020-04-27 | 2021-11-04 | Saudi Arabian Oil Company | Methods of determining cation exchange sites occuped by crude oil and the wettability of cation exchange sites in rock core samples in a non-preserved state |
| WO2021221693A1 (en) * | 2020-04-27 | 2021-11-04 | Saudi Arabian Oil Company | Methods of determining cation exchange sites in rock core samples |
| US11300494B2 (en) | 2020-04-27 | 2022-04-12 | Saudi Arabian Oil Company | Methods of determining cation exchange sites in rock core samples |
| US11555812B2 (en) | 2020-04-27 | 2023-01-17 | Saudi Arabian Oil Company | Methods of determining cation exchange sites occupied by crude oil and the wettability of cation exchange sites in rock core samples in a non-preserved state |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9026265D0 (en) | 1991-01-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |