GB2149100A - An oil discrimination technique - Google Patents
An oil discrimination technique Download PDFInfo
- Publication number
- GB2149100A GB2149100A GB08427616A GB8427616A GB2149100A GB 2149100 A GB2149100 A GB 2149100A GB 08427616 A GB08427616 A GB 08427616A GB 8427616 A GB8427616 A GB 8427616A GB 2149100 A GB2149100 A GB 2149100A
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- United Kingdom
- Prior art keywords
- oil
- sample
- absorbance
- parameter
- base oil
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- 238000000034 method Methods 0.000 title claims description 19
- 238000005553 drilling Methods 0.000 claims abstract description 23
- 239000002199 base oil Substances 0.000 claims abstract description 22
- 239000003921 oil Substances 0.000 claims abstract description 20
- 238000002835 absorbance Methods 0.000 claims abstract description 18
- 239000012530 fluid Substances 0.000 claims abstract description 13
- 238000005520 cutting process Methods 0.000 claims abstract description 7
- 230000005855 radiation Effects 0.000 claims abstract description 5
- 238000002834 transmittance Methods 0.000 claims abstract description 3
- 229930195733 hydrocarbon Natural products 0.000 claims description 11
- 150000002430 hydrocarbons Chemical class 0.000 claims description 9
- 239000000463 material Substances 0.000 claims description 8
- 238000000870 ultraviolet spectroscopy Methods 0.000 claims description 2
- 230000015572 biosynthetic process Effects 0.000 abstract description 7
- 238000001228 spectrum Methods 0.000 description 18
- 239000010779 crude oil Substances 0.000 description 17
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical group ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 13
- 239000000243 solution Substances 0.000 description 9
- 239000004215 Carbon black (E152) Substances 0.000 description 8
- 238000004458 analytical method Methods 0.000 description 7
- 238000005755 formation reaction Methods 0.000 description 6
- 238000012935 Averaging Methods 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 3
- 238000000862 absorption spectrum Methods 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
- 239000012088 reference solution Substances 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 125000003118 aryl group Chemical group 0.000 description 2
- 238000004364 calculation method Methods 0.000 description 2
- 230000036571 hydration Effects 0.000 description 2
- 238000006703 hydration reaction Methods 0.000 description 2
- 125000001183 hydrocarbyl group Chemical group 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 1
- 239000004809 Teflon Substances 0.000 description 1
- 229920006362 Teflon® Polymers 0.000 description 1
- 239000011358 absorbing material Substances 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000002734 clay mineral Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 239000002283 diesel fuel Substances 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000013618 particulate matter Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000011197 physicochemical method Methods 0.000 description 1
- -1 polypropylene Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 238000013341 scale-up Methods 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 238000011895 specific detection Methods 0.000 description 1
- 238000002798 spectrophotometry method Methods 0.000 description 1
- 230000008961 swelling Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/33—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using ultraviolet light
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
- E21B49/005—Testing the nature of borehole walls or the formation by using drilling mud or cutting data
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/314—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
Landscapes
- Physics & Mathematics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Mining & Mineral Resources (AREA)
- Engineering & Computer Science (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Geology (AREA)
- Geochemistry & Mineralogy (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Fluid Mechanics (AREA)
- Environmental & Geological Engineering (AREA)
- Health & Medical Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
Oil-based drilling fluid is analysed for presence of indigenous formation oil. A well sample, derived from returned mud, core or cuttings, is subjected to ultra-violet radiation and a parameter related to absorbance, transmittance or emittance at selected wavelengths is measured. This parameter is compared with a like parameter at the same wavelengths for the base oil of the drilling fluid. Preferably, absorbance is used, and the comparison is effected by solution of simultaneous equations defined in the description.
Description
SPECIFICATION
An oil discrimination technique
This invention relates to the analysis of cuttings and drilling fluid to distinguish between indigenous formation oil and diesel or "clean" oil from the drilling fluid.
The present invention concerns the application of a physico-chemical method of analysis to the problem of specific detection and determination of hydrocarbon material derived from mixtures of crude oil from a rock formation and the diesel of "clean" oil present in an oilbased drilling fluid.
The technique of drilling a well with oilbased muds is well-estblished and such materials are used for the following reasons:- (i) to control the hydration of claystone horizon that would occur with water-based muds.
The latter, water-based fluids cause hydration of certain clay minerals, leading to swelling of the formation and consequent clogging of the pore spaces adjacent to the bore-hole; (ii) lubrication of the drill-bit, leading to faster drilling rates and thereby reducing overall drilling times. Hitherto, diesel oil has been used as base oil, but is now being replaced on environmental grounds by so called "clean" or "invert" oils of low aromaticity; (iii) the ability to drill to deeper depths; (iv) to reduce the conflict between geologists and drilling engineers when formation changes dictate the need for frequent drill-bit changes and hence large down-times.
One of the problems associated with the use of oil based fluids remains, however, namely the identification of hydrocarbon-bearing horizons in the presence of hydrocarbon material in a mud is detected by the observation of fluorescence from hydrocarbons irradiated with ultra-violet energy. However, both the mud oil and the formation oil fluorescence cause difficulty in discrimination.
Such an analysis is important in order to determine the top of a section, so that coring may take place (ie to detect the core-point), to ascertain whether the drill-bit is still in an oil bearing section and to find the oil-water interface.
Therefore, there is a requirement for a technique that will allow material returned to the surface with the drilling mud to be examined, rapidly, for the presence of indigenous hydrocarbon. The object of the present invention is to provide such a method.
"Clean" or "Invert" drilling oils differ from crude oil in their n-alkane distribution and aromatic content. Hence the quality and type of fluorescing and ultra-violet absorbing constituents vary considerably. Since the "clean" oils have been refined to reduce the aromatic content, most crude oils contain significantly more ultra-violet absorbing species.
The object of the invention is achieved, therefore, by subjecting the sample, or an oil containing extract thereof, to ultra-violet radiation, obtaining a parameter for absorbance, transmittance or emittance of the sample or extract at selected wavelengths, and comparing the parameters obtained with similar parameters at the same wavelengths for samples of the base oil of the drilling fluid.
The invention is based on the significant differences that exist in the parameters obtained at the selected wavelengths for the absorbing species contained in the indigenous crude oil, and those present in the low aromaticity base oil. A comparison of these sets of parameters enables a qualitative estimate of the hydrocarbon content of a sample (or extract thereof) to be made. However, if comparison of the parameters is made at two specific wavelengths for the sample (or extract thereof) and the base oil, in which the parameters are determined for known concentrations of the base oil and the crude oil (of the types known to be present at the exploration site), then a quantitative determination of the crude oil in any sample (or extract thereof) under test, may be achieved.
The analysis technique employed in the invention is preferably ultra-violet absorption spectrophotometry and the parameter utilised for detecting the presence of the indigenous hydrocarbons is by absorbance at two or more selected wavelengths. However, the basing of the invention on the extent of the emitted fluorescence detected laterally to the incident
UV radiation is envisaged, also.
The method of the invention may be accomplished on samples of drilling mud, cuttings or core coming to the surface, the former being much preferred. The analysis is best performed on an extract (from which insoluble particulate matter has been removed) of the sample in an organic solvent which is substantially UV transparent at the wavelengths under consideration. The preferred solvent is methylene chloride.
When an oil-based mud is circulated in the course of drilling a well, absorption of UV absorbing material occurs. The absorbance of a used drilling fluid, therefore, can be many times that of a freshly prepared mud. However, such changes do not prevent the detection of a sudden change in absorption of the fluid, for example as a result of circulating "bottoms-up" at a drilling break at the point of entry into a reservoir.
For practical purposes therefore the parameters for the base oil are obtained, preferably, from a sample thereof, extracted (eg with methylene chloride) from mud or cuttings returned to the surface. The reason for this requirement relates to the UV absorbance and fluorescence characteristics of the base oil, which may be altered (on its passage from the surface to the drill-bit and back to the surface) by "contamination" due to mixing with for mation crude oil. Such measurement ensures that the parameters of the base oil in the sample under analysis and in the "reference" sample are identical, and, thus, that any differences are due to the presence of indigenous oil.
Two exemplary methods of carrying out the invention are as follows.
Example 1
A sample of mud (5 cm3) taken by automatic pipette from the ditch line is diluted with 50 cm3 of methylene chloride and filtered using a hypodermic syringe and a teflon disc filter attached to the syringe. The filtrate is passed directly to the spectrometer cuvette and the parameter measured allowing for the dilution factor. The experimental error incurred in this technique is no greater than that expected in normal spectrophotometry (viz around 0.5%).
Example 2
In order to compensate for weighing errors caused by heave and vibration, weighings are accomplished using a mass averaging balance. The averaging computer programme for the balance is incorporated within the main computer programme so that any masses are compensated automatically during the calculation.
A sample of mud and cuttings (5 g) from the shale shaker is shaken in a sealed glass vial with methylene chloride (10 ml) and allowed to settle. A volume (0.03 cm3) of the separated liquid is filtered using a hypodermic syringe and attached filter into a quartz spectrometer cuvette (1 cm) and the required parameter measured by scanning over the requisite UV range.
Equipment suitable for Examples 1 and 2: 1. Syringe: 25 mm3 (polypropylene) 2. Filter: 0.4 micron 1.5 cm dia. PTFE
Gelman Science 3. Cuvettes: 1 cm path length matched quartz 4. Spectrophotometer: specifically designed
to scan the range of wave lengths in the
UV that are required for the method and
to withstand the rigours of the rig envi
ronment in which measurement is made
A further factor considered in the design
of the instrument concerned is its physi
cal size to allow for the confined space
available on board a drilling rig 5. Balance: weight averaging balance Saito
rius Model 1 408 (100 g - 1 mg range) 6. Computer: integral with the spectrophoto
meter 7. Modem: integral with the spectrophoto
meter 8. Range of 'A' quality volumetric glassware 9. Automatic pipettes: Gilson 1 cm3, 5 cm3 10.Dichloromethane (methylene chloride)
(Analytical reagent grade) 11. Plotter: any suitable plotter.
This invention is further illustrted by way of example only with reference to the accompanying drawings in which: Figure 1 shows the UV absorbance spectra for solutions of base oil and indigenous hydrocarbon of known concentration:
Figure 2 shows the UV absorbance spectra for an organic solvent extract of a sample of drilling mud returned to the surface; and
Figure 3 is a histogram of results from a practical experiment.
In Fig. 1, spectrum A represents the UV absorbance spectrum of a 1% w/v solution of base oil (eg Inverkleen) extracted from a mud sample returned to the surface and which is known not to contain indigenous hydrocarbon. Spectrum B is obtained from a 1% w/v solution of the crude oil of the type known to be present in the area of exploration.
The spectrum S shown in Fig. 2 is that of an organic solvent extract (X) of a crude oil containing sample of mud of known weight returned to the surface.
The spectra of Figs. 1 and 2 may be scanned over the range 230-350 nm. Within this range two wavelengths Al and A2 are selected at each of which there are substantially different absorbances between the base oil and crude oil. Generally the difference in absorbance should be at least 10%.
The values of Al and A2 may, for example, be in the region of 257 and 320 respectively.
Now, let concentration of base oil in the solvent
X extract X = C
A concentration of crude oil in the solvent
X extract X= C
B absorbance of base oil solution at Al (Spectrum A)
A
= E
Al absorbance of crude oil solution at Al (Spectrum B)
B
= E Al absorbance of base oil solution at A2 (Spectrum A)
A
= E
A2 absorbance of crude oil solution at A2 (Spectrum B)
B
= E
A2 absorbance of sample oil solution at Al (Spectrum S)
S
= E Al absorbance of sample soil at A2 (Spectrum S)
S
= E
A2
Two simultaneous equations may be set up as follows
A B S
E +C E =E -1
A Al B Al Al A B S
E +C E =E -2
A A2 B A2 A2
All of the E values are known so that equations 1 and 2 may be solved to obtain
X X
C and C
A B ie the concentrations of base oil and crude oil respectively in the sample extract from the mud. It is thus possible to establish the concentration of crude oil in the original sample of mud.
It will have been noted that the concentration of the reference solutions of base oil and crude oil for spectra A and B have been set as 1%. This is to ensure that the concentrations
CA and CB may be obtained from equations 1 and 2. It is possible to run spectra on the reference solutions at concentrations other than 1% and scale up the spectra to a nominal 1% concentration. Alternatively allowance may be made in equation 1 and 2 for the fact that the reference solutions ar.e not of 1% concentration.
The analysis method described with reference to the drawings may be completed within 1 5 minutes, including time required for the preparation of the solution for running spectrum S. It will of course be appreciated that spectra A and B are reference spectra and need not be repeated each time a fresh sample of mud or cutting is to be analysed. It should however be noted that the reference spectrum for the base oil (ie spectrum A) should be repeated periodically as the absorption characteristics of the base oil may change with time.
The calculation is based on the Beer-Lambert law-viz lo log- Elc
It where lo is the incident intensity
It is the transmitted intensity
E is the molar absorptivity
I is the cill path length (1 cm)
c is the concentration in g uvl/dm3
The latter unit assumes a knowledge of the molecular weight of the material which is not known in the current application. Hence
10%
E
1 cm values are used instead of E.
The computer programme is used to calculathe: (i) C,---concentration of base oil (ii) C,---concentration of crude oil from the basic simultaneous equation using the weight of sample from the balance. The computer then calculates
CB x100 (CA+CB) and plots this figure automatically against depth.
The method has been tested under rigorous conditions and has been proved to behave correctly. The results shown in Table I are from a North Sea well and show three major hydrocarbon regions that are more obvious in the histogram shown in Fig. 3.
TABLE I
Ultra-violet Absorbance of Samples
Spot sample depth or E(1 %) interval range--ft.
6600 0.79
0.95 6920 1.19
1.08 7080-7100 0.72 7100-7120 0.85 7120 0.77 7120-7140 1.41 7140-7160 1.13 7160-7180 0.87 7380 1.28 7510 0.97 7720 0.87 7940 2.77 8220 1.16
Claims (8)
1. A method of analysing oil-based drilling fluid, comprising separating a sample from material returned from the drilling bore, subjecting the sample, or an oil containing extract thereof, to ultra-violet radiation, obtaining a parameter for absorbance, transmittance or emittance of the sample or extract at selected wavelengths, and comparing the parameters obtained with similar parameters at the same wavelengths for samples of the base oil of the drilling fluid.
2. The method of claim 1, in which the parameter is absorbance.
3. The method of claim 2, in which the sample and the base oil are examined by ultra-violet absorption spectrophotometry and the parameter utilised for detecting the presence of the indigenous hydrocarbons is by absorbance at two or more selected wavelengths.
4. The method of claim 1, in which said parameter is determined from the extent of the emitted fluorescence detected laterally to the incident UV radiation.
5. The method of any preceding claim, in which said material is drilling mud.
6. The method of any of claims 1 to 4, in which said material comprises cuttings or core.
7. The method of any preceding claim, in which said comparison is effected by solution of equations 1 and 2 hereinbefore defined.
8. A method of analysing oil-based drilling fluid substantially as herein described with reference to the Examples and/or drawings.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08329089A GB2151017B (en) | 1983-11-01 | 1983-11-01 | Analysis of material from a drillhole |
| GB848426962A GB8426962D0 (en) | 1984-10-25 | 1984-10-25 | Oil discrimination technique |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8427616D0 GB8427616D0 (en) | 1984-12-05 |
| GB2149100A true GB2149100A (en) | 1985-06-05 |
Family
ID=26286957
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08427616A Withdrawn GB2149100A (en) | 1983-11-01 | 1984-11-01 | An oil discrimination technique |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2149100A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103217393A (en) * | 2013-04-01 | 2013-07-24 | 华南农业大学 | Detection method for adulterated tea oil |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB822848A (en) * | 1957-03-28 | 1959-11-04 | Evans Electroselenium Ltd | Improvements in or relating to fluorimeters |
| GB1208031A (en) * | 1967-04-25 | 1970-10-07 | Honeywell Inc | Improvements in or relating to fluorimeters for providing a continuous measurement of the fluorescence of a fluid stream |
| GB1426005A (en) * | 1972-09-21 | 1976-02-25 | Baxter Laboratories Inc | Dual wavelength photometer for absorbance difference measurements |
| GB1438631A (en) * | 1972-08-04 | 1976-06-09 | Parsons & Co Sir Howard G | Analysis of emulsions and suspensions |
| GB1458733A (en) * | 1973-04-16 | 1976-12-15 | Hitachi Ltd | Spectrophotometers |
| GB1478058A (en) * | 1973-08-27 | 1977-06-29 | Max Planck Gesellschaft | Method for photometric measurement of concentration ratios |
| GB1595785A (en) * | 1977-10-28 | 1981-08-19 | Water Res Centre | Optical analysis of liquids |
-
1984
- 1984-11-01 GB GB08427616A patent/GB2149100A/en not_active Withdrawn
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB822848A (en) * | 1957-03-28 | 1959-11-04 | Evans Electroselenium Ltd | Improvements in or relating to fluorimeters |
| GB1208031A (en) * | 1967-04-25 | 1970-10-07 | Honeywell Inc | Improvements in or relating to fluorimeters for providing a continuous measurement of the fluorescence of a fluid stream |
| GB1438631A (en) * | 1972-08-04 | 1976-06-09 | Parsons & Co Sir Howard G | Analysis of emulsions and suspensions |
| GB1426005A (en) * | 1972-09-21 | 1976-02-25 | Baxter Laboratories Inc | Dual wavelength photometer for absorbance difference measurements |
| GB1458733A (en) * | 1973-04-16 | 1976-12-15 | Hitachi Ltd | Spectrophotometers |
| GB1478058A (en) * | 1973-08-27 | 1977-06-29 | Max Planck Gesellschaft | Method for photometric measurement of concentration ratios |
| GB1595785A (en) * | 1977-10-28 | 1981-08-19 | Water Res Centre | Optical analysis of liquids |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103217393A (en) * | 2013-04-01 | 2013-07-24 | 华南农业大学 | Detection method for adulterated tea oil |
| CN103217393B (en) * | 2013-04-01 | 2015-04-08 | 华南农业大学 | Detection method for adulterated tea oil |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8427616D0 (en) | 1984-12-05 |
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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) |