JPH0750093B2 - Oil indication identification method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for identifying oil characteristics performed when an oil well is excavated, and more specifically, a circulating mud using liquid chromatography equipped with a fluorescence detector or the like. Alternatively, the presence of the oil layer is determined by analyzing the cuttings and quantifying the light aromatic hydrocarbon components derived from crude oil such as benzene, toluene, and xylenes (o-, m-, p-xylene) contained in the cuttings. The present invention relates to an oil characteristic identification method for detecting the.

[Conventional technology]

At the drilling site of oil and gas wells, oil and
It is important to quickly and accurately detect whether or not the gas layer has been reached. As a method therefor, conventionally, a method of analyzing so-called mud gas released from muddy water and a method of observing a fluorescent reaction of cores and cuttings (digging waste) have been used.

Mud gas is a gas obtained by introducing circulating mud into a degasser, and by analyzing this, various underground information can be known. If it contains hydrocarbon gas such as methane, ethane, propane, butane, pentane, etc., it indicates the existence of the hydrocarbon-containing layer.

Methods for detecting hydrocarbons in the mud gas include a method using a heat ray detector, a thermal conductivity difference detector, an infrared absorption detector, and a method using a gas chromatograph. For example, in a heat ray detector, when a mud gas containing hydrocarbons flows, the heat rays act as a combustion catalyst, and the temperature rises, so that the electrical conductivity changes, so the hydrocarbon gas concentration is detected by the degree of this change. be able to. The heat ray detector has an advantage that it can be easily and continuously recorded, but has disadvantages such as poor quantitativeness and inability to detect the property of gas. Therefore, it has not been used much recently. Thermal conductivity difference detectors and infrared absorption detectors have similar drawbacks.

On the other hand, the gas chromatographic method can intermittently measure the respective concentrations of the hydrocarbon gas components in the mud gas in a relatively short cycle. Gas chromatographic method is an extremely effective method because it is important to identify hydrocarbons from methane to pentane or hexane for the detection of hydrocarbon-containing layers associated with mine powder. It is the mainstream.

However, even if the presence of light hydrocarbons such as methane and ethane in the mud gas is confirmed, it cannot be immediately judged as an oil sign. This is because these hydrocarbons are detected not only in crude oil but also in the presence of natural gas or coal. Therefore, it is necessary to compare and analyze with the past data based on the obtained analysis value, and to confirm the existence of crude oil, it is necessary to make a comprehensive judgment in association with other geological information.

On the other hand, the fluorescence reaction method is a method for directly detecting whether or not crude oil is present underground. This is a method of irradiating cores or cuttings with ultraviolet light and observing the degree and color tone of the fluorescent reaction with the naked eye to identify oil marks. If there is oil from crude oil on them,
Or if they remain in the pores, the unique fluorescent reaction from the polycyclic aromatic compounds contained in them can be detected,
It can be said that it is a more direct oil characteristic identification method. In the case of the fluorescence reaction method, it is widely used because the device used and the measurement operation are simple.

However, in the case of the fluorescence reaction method, since it depends on the naked eye observation, it depends on the experience and intuition of the observer, and there are individual differences in the determination results. Further, there is a drawback that the presence of relatively light oil such as gas condensate associated with the gas layer cannot be detected. In addition, it is necessary to pay sufficient attention to contamination by circulating mud during measurement. For muddy water, various chemicals such as surfactants and light oil, in order to cope with various conditions during excavation,
Petroleum products such as heavy oil are used. Some chemicals are made from petroleum. Originally, these muddy water materials
It should not contain any substances that hinder oil identification, but recently, in addition to the diversification of drilling conditions,
Due to economic reasons, materials tend to become heavier, and they show the same fluorescent reaction as crude oil, so that they are often mistaken for oil. In order to avoid this, various measures have been taken in the method of cleaning the cuttings before the measurement, but it cannot be said to be sufficient.

Recently, a new technology has been announced as a supplement to the drawbacks of the oil signature identification method. For example, (1) VT Jones et al. Of Exploration Technologies, Inc. of the United States have reported a method of detecting benzene and toluene contained in circulating mud water by a second derivative ultraviolet absorptiometry (US USA Published by The Chemistry Society, 194th American Chemical Society National Meeting, Book of Abstracts, Geochemistry Division, Organic Geochemistry Symposium, 19th Lecture 1987). This method differs from the above-mentioned gas chromatographic method in that benzene and toluene are derived only from crude oil, and thus is a method for directly identifying the oil characteristic.

(2) H. Denbicky and colleagues from Conoco, Inc. of the United States heated circulating mud to 300 ° C to evaporate all the hydrocarbons contained in it, and analyzed it by gas chromatography to determine the heating time and detection. We are trying to estimate the oil type from the release curve diagram showing the relationship between the amount of hydrocarbons and the pattern of the hydrocarbon chromatogram (SPE) Formation Evolution, published by the American Petroleum Institute of Technology. Pp.331-331, 1986
Year).

In addition, (3) AE Worthington et al., A method in which isooctane was added to muddy water and steam distillation was performed to quantify gasoline components by gas chromatography and aromatic compounds such as benzene, toluene, and xylene by infrared absorption spectrometry. (US Patent No. 3,118,
No. 299).

[Problems to be solved by the invention]

In the case of the method (1), the mud gas is used as the sample as in the gas chromatographic method, and the components in the mud water are not directly analyzed. In addition, since the detection sensitivity is increased in terms of the apparatus, the optical system is complicated, such as lengthening the optical path, and special arithmetic processing is required.

The method (2) is different from the method (1) in that mud water is directly analyzed, but since one analysis takes 1 hour or more, it is a method suitable for analysis at a wellhead. It is hard to say. Further, in the case of the method (3), although the muddy water is directly measured, it is not suitable for the analysis at the wellhead since it requires a troublesome pretreatment such as steam distillation.

This invention focuses on the fact that light aromatic compounds such as benzene, toluene, and xylene are universally contained in crude oil and condensate, but not in mud materials, and the drilling site of oil wells In which the circulating mud or cuttings were analyzed by liquid chromatography,
It is an object of the present invention to provide an oil characteristic identifying method capable of rapidly detecting the presence of an oil layer by detecting the light aromatic compound.

[Means for Solving the Problems]

In order to achieve the above object, in the oil identification method of the present invention, at the drilling site of an oil well, circulating mud or cuttings are collected and analyzed by liquid chromatography, and the benzene contained therein is collected. , Toluene, o-
The presence of crude oil or gas condensate is detected by detecting all or one or more components of xylene, m-xylene, p-xylene.

In addition, a fluorescence detector is used as a detector for liquid chromatography, and in the case of circulating mud, the operations from collection to measurement by liquid chromatography are automatically performed.

Next, the present invention will be described in detail.

As an apparatus for performing liquid chromatography,
A commercially available normal liquid chromatography can be used. This will be explained with reference to FIG. 1. The liquid suction pipe 9 of the pump 2 for sending the eluent is connected to the eluent tank 1, and the liquid feed pipe 10 of the pump 2 is connected to the sample inlet of the sample injection device 3. The sample supply port of the sample injection device 3 is connected to the sample inlet of the separation column 4 housed in the constant temperature layer 5 via a pipe 12, and the sample outlet of the separation column 4 is connected to the sample inlet of the detector 6. It is connected via piping 13 to
In addition, the waste liquid outlet of the detector 6 is connected to the waste liquid tank 8 via the pipe 14.
Further, the data processing device 7 is connected to the detector 6 via the signal wiring 15, and the sample introduction pipe 11 is connected to the sample inlet of the sample injection device 3.

When injecting the circulating mud into the separation column 4 of the liquid chromatograph shown in FIG. 1, the solid matter in the circulating mud is removed by filtration or centrifugation, and then the circulating mud is removed.
The sample is injected from the sample injection device 3 into the separation column 4 via the sample introduction pipe 11 by a microsyringe. In the case of cuttings, extraction is performed using a solution having the same composition as the eluent, and the extracted solution is injected into the separation column 4 by a microsyringe in the same manner as in the case of circulating mud.

The sample injection device 3 is provided with a switching cock, and after injecting the sample, the cock is manually operated so that the eluent can be flushed toward the separation column 4 so that the flow path of the eluent is changed. Switch.

In addition to this, in order to prevent deterioration of the column and shorten the analysis time, a backflush function for backflowing the component flowing out after the target component may be provided, if necessary.

The packing material of the separation column 4 and its average particle diameter, the inner diameter and the length of the separation column are determined in consideration of the degree of separation of the target component and the time required for analysis. That is,
It is necessary to select benzene, toluene, and xylenes (hereinafter referred to as BTX) that completely separate from other components and that the analysis time is as short as possible. As the packing material for the separation column 4, a chemical bond type packing material used in ordinary reverse phase liquid chromatography can be used.
For example, octadecylsilane in which an octadecyl unit is chemically bonded to the surface of spherical silica gel, or octylsilane in which an octyl group is chemically bonded is suitable for carrying out the present invention. The average particle size of these fillers is 3 to
It is possible to use the one having 5 μm. The inner diameter and the length of the separation column are, for example, 4.6 mm in inner diameter when a packing material having an average particle size of 5 μ is used and a stainless tube having a length of 15 to 20 cm, 4.6 mm in the case of a packing material having an average particle size of 3 μ, A stainless tube having a length of 5 to 10 cm may be used.

As the eluent, a solution in which an organic solvent such as methanol or acetonitrile and water are mixed at a volume ratio of 95/5 to 60/40, preferably 85/15 is used.

The detector 6 can be attached to a liquid chromatography, and is an aromatic compound, particularly the object of the present invention.
Any detector that can detect BTX can be used. For example, a commercially available detector for liquid chromatograph, such as an ultraviolet absorption detector, a differential refractive index detector, and a fluorescence detector, can be used, but by using the fluorescence detector, the effect of the present invention is maximized. Be utilized to the limit.

As the fluorescence detector, it is preferable to use at least an excitation wavelength of 240 to 265 nm, a fluorescence wavelength of 265 to 300 nm, and a difference of at least 4 nm between the excitation wavelength and the fluorescence wavelength. The excitation and fluorescence wavelengths of the fluorescence detector may be set to values suitable for BTX detection. Usually, for detection of BTX, for example, excitation wavelength 256 nm, fluorescence wavelength
278 nm is used. However, in this case, many monocyclic aromatic hydrocarbons other than BTX are also detected, the chromatogram becomes complicated, and the analysis time becomes long. In order to maintain a certain degree of separation accuracy and to shorten the measurement time as much as possible, the inventors of the present invention have earnestly studied, and as a result, the wavelength of the fluorescence detector was set to the excitation wavelength 26
It has been found that it is most preferable to set the wavelength to 5 nm and the fluorescence wavelength to 269 nm.

That is, by setting the wavelength of the fluorescence detector to this condition, it is possible to detect a target monocyclic aromatic hydrocarbon such as BTX among complicated compounds contained in a large number of circulating mud or cuttings or crude oil. , And is performed selectively as compared with the case of using other wavelengths, thus simplifying the chromatogram and enabling measurement in a relatively short cycle.

For example, a length of 15 cm filled with a filler with an average particle size of 5μ
When the separation column of 1 is used, one analysis can be completed in about 5 to 10 minutes. Normally, the drilling speed of oil wells is 0.
Since it is 1 to 1 m / min, in this case, data can be obtained at every excavation depth of 0.5 to 10 m. A change chart is created based on the BTX concentration for each depth obtained in this way, and the presence or absence of oily signs is determined from this chart.

Next, the outline of the analysis operation will be described.

1-5 ml, preferably 3 ml of circulating mud was collected from the well drilling site and placed in an appropriate container with a 10-20 ml capacity lid, which was mixed at a volume ratio of 85/15 methanol / water mixture Dilute with solvent to 3 to 15 ml, preferably 10 ml. For cuttings, 1-5g, preferably 3g
Was taken from the well drilling site and, like the case of circulating mud,
Put in a container with a lid, and mix methanol / water 3 ~
Add 15 ml, preferably 10 ml. After lidding, shake for a few minutes by hand or with a suitable device to extract circulating mud or components in the cuttings. The supernatant liquid separated as it is or after standing for several minutes is sucked up with a syringe or the like, filtered using a filter paper or a glass filter, etc., and the solid content is removed to obtain a sample to be injected into a separation column of a liquid chromatograph. In order to avoid adverse effects such as clogging of the separation column, the pore size of the filter medium is preferably 0.5 μm or less.

Instead of filtration, the solid content can be removed by a centrifugation method. In case of circulating mud, collect the collected sample with methanol
Without diluting with a water-mixed solvent, 5 to 15 ml, preferably 10 ml, can be directly applied to a centrifuge to separate the solid content.

In a liquid chromatograph, an eluent prepared by mixing methanol and water in a volume ratio of 95/5 to 60/40, preferably 85/15, is injected into a packing material packed in a separation column prior to sample injection. Flow at a flow rate of 0.5 to 3 ml / min, preferably 1 to 1.5 ml / min. The filtrate of the sample is sucked up by a microsyringe of 10 to 50 µ, and a fixed amount thereof is injected into a dividing column of a liquid chromatograph. The injection amount may be read on the scale of a microsyringe, or may be injected using a loop (a stainless tube having a fixed amount).

The peak area of the target component of the obtained chromatograph is determined by a data processing device, and the concentration of each component in mud water is determined from these values.

Benzene, toluene, and xylenes are detected and quantified at regular intervals according to the drilling depth, and the presence of crude oil and the like is detected from the changes in their concentrations.

The above operation may be manually performed for one sample from pretreatment to analysis, or only some samples may be manually pretreated and the analysis may be automatically performed using an autosampler.

Further, in the case of circulating mud, the operations from sampling to analysis can be automatically performed. In that case, as shown in FIG. 2, an automatic sample pretreatment device is connected before the liquid chromatograph.

In FIG. 2, the circulating mud is continuously sent from the excavation site 16 to the mixer 18 by the pump 17. On the other hand, the diluting liquid stored in the diluting liquid tank 19 is supplied to the mixer 18 by the pump 20 at a constant flow rate. The circulating mud water diluted and mixed in the mixer 18 is sent to a solid matter separating device 21 such as a filtering device or a centrifugal separator. Here, the sample such as the filtrate or the centrifugally separated liquid from which the solid matter is separated is sent to the sample injection device 3 for liquid chromatography. As in the case of FIG. 1, the eluent is sent from the eluent tank 1 to the sample injection device 3 by the pump 2. The eluent is sent from the sample injection device 3 to the separation column 4. The sample is sent from the sample injection device 3 to the separation column 4 together with the eluent as required. The sample is injected into the separation column 4 by automatically switching the switching cock of the sample injection device 3 with the timer 22 or the like according to the measurement time. The sample exiting the solid separation device 21 is sent to the waste liquid tank 23 until the next analysis.

〔Example〕

Hereinafter, the content of the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

Example 1 3 ml of mud water collected at a well drilling site was put in a container having a capacity of about 20 ml, and 10 ml of methanol / water (volume mixing ratio: 85/15) was added to the container.
ml, shaken several times, and filtered about 3 ml with 0.45μ filter paper. About 20μ of the obtained filtrate, a fluorescence detector was used as the detector 6 in the liquid chromatography shown in FIG. 1, and Using a separation column in which a stainless steel tube having a diameter of 4.6 mm and a length of 20 cm was filled with octadecylsilane having an average particle diameter of 5 μ, the excitation wavelength of the fluorescence detector was 265 nm and the fluorescence wavelength was 269 nm. Methanol / water (volume mixing ratio: 85/15) was used as an eluent, and was passed at a flow rate of 1 ml / min. The analysis results are shown in FIG. According to the result of this analysis, since the aromatic compounds such as toluene and xylene are detected, the existence of the oil layer can be known.

Example 2 In an oil drilling well, analysis was performed under the same conditions as in Example 1 with the toluene and m-xylene concentrations in circulating mud water every 10 m up to a drilling depth of 2100 to 2540 m. The results are shown in FIGS.

The concentration of toluene and m-xylene in the circulating mud was 2210.
Although it was below the detection limit up to m, it can be seen that the concentration of these compounds increased at a depth deeper than 2220 m. Based on the results of electrical logging and some other physical means after the completion of excavation, as shown in Fig. 4 I and II.
2310-2360 (A layer), 2372-2407m (B layer), 2418-246
Various layers of 8 (C layer) and 2481 to 2502 m (D layer) were finished as producible layers. When this finishing is performed, for example, a casing pipe to which a perforated pipe is connected is inserted into a well, the perforated pipe is positioned in the collection layer, and then the well peripheral wall and the casing pipe are located above the collection layer. Curable material such as cement is filled in between.

As a result of performing a production test on each of these finished layers, production of condensate along with gas was confirmed from all the layers. As shown in Fig. 4 I and II, 2220
At depths deeper than m, the concentrations of toluene and m-xylene tend to increase, which corresponds to the presence of condensate.

Comparative Example In the same well as in Example 2, the mud gas separated from the muddy water was analyzed by the conventional gas chromatographic method at intervals of 1 to 5 m. The resulting changes in the total mud gas (total amount of gaseous hydrocarbons analyzed by gas chromatography, indicated as TMG in Fig. 4) and the concentration of methane gas in the total mud gas are shown in Fig. 4 III, IV
Shown in.

In the change map of total mud gas (TMG) and methane, some remarkable peaks were recognized up to the excavation depth of 2210 m, but toluene and m-xylene were not detected at this depth at all. Therefore, it is expected that the stratum around this area contains methane-based gas, but does not contain condensate or crude oil.

On the other hand, in the stratum deeper than 2220 m, peaks appear continuously in the change map of total mud gas (TMG) and methane, and peaks are also observed in the change map of toluene and m-xylene. This indicates the possible presence of condensate or crude oil with gas in these formations.

As described above, in the conventional gas chromatographic method, it is difficult to know whether or not condensate or crude oil exists in the formation, even if the existence of gas such as methane can be known in the process of excavation. This is possible with the method described in (1) and provides useful information in drilling oil wells.

〔The invention's effect〕

Since the present invention is configured as described above, it has the following effects.

Circulating muddy water or cuttings at oil well drilling sites are analyzed after a relatively simple pretreatment and then analyzed for benzene, which is universally found in crude oil but not in mud materials. Since toluene, xylenes are detected and quantified, the presence of the oil layer can be detected more directly and more rapidly than in the conventional method. In addition, compared to the fluorescence reaction method, there is no individual difference in the determination of results,
Moreover, it is possible to detect a clear oil sign without concern about contamination by petroleum-based muddy water materials. Furthermore, by automating the operation, it can be a new mud logging method that replaces the gas chromatographic measurement method for mud gas, which greatly contributes to the petroleum development field.

[Brief description of drawings]

FIG. 1 is a diagram showing the constitution of liquid chromatography, and FIG.
Figure shows the configuration of liquid chromatography equipped with an automatic sample pretreatment device, Figure 3 shows the liquid chromatogram of circulating mud water, and Figure 4 shows the drilling depth of wells and toluene in circulating mud water. It is a figure which shows the relationship with the density | concentration of m-xylene. In the figure, 1 is an eluent tank, 2 is a pump, 3 is a sample injection device, 4 is a separation column, 5 is a constant temperature bath, 6 is a detector,
7 is a data processor, 17 is a pump, 18 is a mixer, 19 is a diluent tank, 20 is a diluent pump, 21 is a solids separation device,
22 is a timer.

Claims (3)

[Claims] 1. At the drilling site of an oil well, circulating mud or cuttings is sampled and analyzed by liquid chromatography, and benzene, toluene,
A method for identifying oil characteristics, which detects the presence of crude oil or gas condensate by detecting all or one or more components of o-xylene, m-xylene, p-xylene. 2. A detector for liquid chromatography,
The oil characteristic identifying method according to claim 1, wherein a fluorescence detector is used. 3. The oil characteristic identifying method according to claim 1, wherein the operations from the collection of the circulating mud to the measurement by liquid chromatography are automatically performed.