JPH03291564A - Method for identifying oil indications - Google Patents

Abstract

PURPOSE:To rapidly detect the presence of an oil layer by analyzing circulating mud water or cuttings with liquid chromatography and detecting light arom. compds. on the excavating site of a petroleum mining well. CONSTITUTION:While the circulating mud water or cuttings are continuously fed to a mixer 18 by a pump 17 from the excavating site 16, the diluting liquid stored in a diluting liquid tank 19 is supplied to a mixer 18 at a specified flow rate by a pump 28. The circulating mud water diluted and mixedby the mixer 18 is sent through a solid separator 21 to a sample injector 3 of the liquid chromatography and a sample is sent at need from the injector 3 together with the eluting liquid from an eluting liquid tank 1 into a sepn. column 4. The peak area of the desired component of the resulted chromatography is determined by a data processor 7 and the concn. of the desired component in the mud water is determined. Detection and determination of benzene, toluene, and xylenes are executed at every specified intervals according to excavating depth and the presence of crude oil, etc., in the ground is detected from a change in the concn. thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for identifying oil signatures performed during drilling of oil wells, and more specifically, the present invention relates to a method for identifying oil signatures during drilling of oil wells. Alternatively, the existence of an oil layer can be detected by analyzing cuttings and quantifying the light aromatic hydrocarbon components derived from crude oil, such as benzene, toluene, and xylenes (om-, p-xylene) contained therein. The present invention relates to a detection method for identifying oil marks.

[Conventional technology]

At oil and gas well drilling sites, oil is released during the drilling process.
It is important to quickly and accurately detect whether the gas layer has been reached. Conventional methods for this purpose include analyzing so-called mud gas emitted from muddy water and observing the fluorescence reaction of cores and cuttings.

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

There are two methods for detecting hydrocarbons in mud gas: a method using a heat ray detector, a thermal conductivity difference detector, an infrared absorption detector, etc., and a method using a gas chromatograph. For example, in a hot ray detector, when mud gas containing hydrocarbons flows, the hot rays act as a combustion catalyst, and as the temperature rises, the electrical conductivity changes, and the hydrocarbon gas concentration is detected by the degree of this change. be able to. Heat ray detectors have the advantage of being easy to use and can record continuously, but they have drawbacks such as poor quantitative performance and inability to detect gas properties, so they are not used much these days. Differential thermal conductivity detectors, infrared absorption detectors, and the like have similar drawbacks.

On the other hand, gas chromatography allows the concentration of each of the hydrocarbon gas components in mud gas to be measured intermittently in relatively short cycles. To detect hydrocarbon-containing layers associated with ore deposits, it is important to identify hydrocarbons ranging from methane to pentane or hexane, so gas chromatography is an extremely effective method and is currently the mainstream mud gas analysis method. It becomes.

However, even if the presence of light hydrocarbons such as methane or ethane is confirmed in mud gas, it cannot be immediately determined that it is 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 past data based on the obtained analytical values, and to confirm the presence of crude oil, it is necessary to make a comprehensive judgment in conjunction with other geological information.

In contrast, the fluorescence reaction method is a method for directly detecting whether crude oil exists underground. This is a method that attempts to identify oil signs by irradiating the core or cuttings with ultraviolet light and observing the degree and color of the fluorescent reaction with the naked eye. If these are contaminated with oil caused by crude oil,
Alternatively, if they remain in the pores, the unique fluorescent reaction from the polycyclic aromatic compounds contained in them can be detected.
This can be said to be a more direct oil signature identification method. The fluorescence reaction method is widely used because the equipment and measurement operations used are simple.

However, since the fluorescence reaction method relies on naked eye observation, it currently relies largely on the experience and intuition of the observer, and there are individual differences in judgment results. Another drawback is that the presence of relatively light oil such as gas condensate accompanying the gas layer cannot be detected. Furthermore, when performing measurements, sufficient attention must be paid to contamination caused by circulating muddy water. To cope with the various conditions during drilling, muddy water is filled with various chemicals including surfactants, light oil,
Petroleum products such as heavy oil are used. Some drugs are made from petroleum. These muddy water materials originally have
Oil should not contain substances that would interfere with oil micro-identification, but recently, in addition to the diversification of drilling conditions,
Due to economic reasons, there is a tendency for materials to become heavier, and because they exhibit a fluorescent reaction similar to that of crude oil, they are often mistaken for oily substances. In order to avoid this, various methods have been used to clean the cuttings before measurement, but these methods are not sufficient.

Recently, new techniques have been announced to compensate for the shortcomings of these oil micro-identification methods. For example, (1) V. T. Jones et al. of Exploration Chinnorrhea Co., Ltd. in the United States reported a method for detecting benzene and toluene contained in circulating mud water using second-order differential ultraviolet absorption spectrophotometry ( Published by American Chemical Society, USA, No. 19
4th American Chemical Society National Meeting, Book
of Abstracts, Department of Geochemistry, Organic Geochemistry Symposium, 19th Lecture, 1987). This method differs from the gas chromatography method mentioned above because benzene and toluene are derived only from crude oil.
This is a method to directly identify oil particles.

(2) Mr. H. Denbicki of Conoco Corporation in the United States and his colleagues heated circulating mud to 300°C to evaporate all the hydrocarbons contained therein, analyzed this using a gas chromatograph, and detected the heating time and An attempt is made to estimate the oil type from the release curve diagram showing the relationship between the amount of hydrocarbons released and the pattern of the hydrocarbon chromatogram (published by the American Society of Petroleum Engineers, SPE).
Formation Evolution Magazine, Volume 1, 331
Page, 1986).

Furthermore, (3) A, E. and Worthington et al. added isooctane to muddy water and performed steam distillation to extract gasoline components by gas chromatography and aromatic compounds such as benzene, toluene, and xylene by infrared spectrophotometry. has proposed a quantitative method (see US Pat. No. 3,118,299).

[Problem that the invention seeks to solve]

In the case of method (1) above, mud gas is used as a sample similarly to the gas chromatography method, and the components in mud water are not directly analyzed. Furthermore, in order to increase the detection sensitivity of the device, the optical system is complicated, such as by lengthening the optical path, and special arithmetic processing is required.

In addition, method (2) differs from method (1) in that it directly analyzes muddy water, but since it takes more than an hour for one analysis, it is suitable for analysis at the wellhead. It's hard to say. Furthermore, in the case of method (3), although muddy water is directly measured, it requires a troublesome pretreatment of steam distillation, so it is not suitable for analysis at the wellhead.

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 are not contained in muddy water materials. Analyzing circulating mud or cuttings by liquid chromatography,
It is an object of the present invention to provide an oil signature identification method that can quickly detect the presence of an oil layer by detecting the light aromatic compounds.

[Means to solve the problem]

In order to achieve the above object, in the oil micro-identification method of the present invention, circulating mud or cuttings are collected at an oil well drilling site and analyzed by liquid chromatography to detect benzene contained therein. , toluene, 0-
The presence of crude oil or gas condensate is detected by detecting one or more components of xylene, m-xylene, p-xylene, or any of these.

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

Next, the present invention will be explained in detail.

Devices for performing liquid chromatography include:
Commercially available ordinary liquid chromatographs can be used. To explain this 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 sending 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 via piping 12 to the sample inlet of the separation column 4 housed in the constant temperature layer 5, and the sample outlet of the separation column 4 is connected to the sample inlet of the detector 6. On the other hand, the waste liquid outlet of the detector 6 is connected to the waste liquid tank 8 via the pipe 14, and the data processing device 7 is connected to the detector 6 via the signal line 15. A sample introduction tube 11 is connected to the sample inlet of the sample injection device 3.

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

The sample injection device 3 is equipped with a switching cock, and after injecting the sample, the cock is manually operated to change the flow path of the eluent so that the eluent can push the sample toward the separation column 4. Switch.

In addition, if necessary, in order to prevent column deterioration and shorten analysis time, a backflush function may be provided to flow back components that flow out after the target component.

The packing material of the separation column 4, its average particle diameter, and the inner diameter and length of the separation column are determined by taking into consideration the degree of separation of target components and the time required for analysis. That is,
It is necessary to select one in which benzene, toluene, and xylenes (hereinafter referred to as BTX) can be completely separated from other components, and the analysis time is as short as possible. Separation column 4
As the packing material, a chemically bonded packing material used in ordinary reversed phase liquid chromatography can be used. For example, octadecylsilane, in which an octadecyl group is chemically bonded to the surface of a 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
~5μ can be used. The inner diameter and length of the separation column are, for example, when using a packing material with an average particle size of 5 μ, a stainless steel tube with an inner diameter of 4.6 mm and a length of 15 to 20 cm, and when using a packing material with an average particle size of 3 μ, an inner diameter of 4.8 mm.
, a stainless steel pipe with a length of 5 to 10 cm may be used.

As the eluent, a solution containing an organic solvent such as methanol or acetonitrile and water mixed in a volume ratio of 9575 to 60/40, preferably 85/15 is used.

As the detector 6, any detector can be used as long as it can be attached to a liquid chromatography device and can detect aromatic compounds, particularly BTX, which is the object of the present invention. For example, commercially available liquid chromatography detectors such as ultraviolet absorption detectors, differential refractive index detectors, and fluorescence detectors can be used, but the effects of the present invention can be maximized by using a fluorescence detector. It will be utilized to the limit.

The fluorescence detector has an excitation wavelength of at least 240 to 265n.
m, the fluorescence wavelength can be set arbitrarily in the range of 265 to 300 nm, and the difference between the excitation wavelength and the fluorescence wavelength is at least 4n.
It is preferable to use one that can be set to m. Furthermore, the excitation and fluorescence wavelengths of the fluorescence detector may be set to values suitable for BTX detection.

Usually, for BTX detection, for example, an excitation wavelength of 256 nm is used.
, a fluorescence wavelength of 278 nm is used. However, in this case, many monocyclic aromatic hydrocarbons other than BTX were also detected,
The chromatogram becomes more complex and the analysis time becomes longer. In order to maintain a certain degree of separation accuracy and shorten the measurement time as much as possible, the present inventor has conducted intensive research and found that it is most preferable to set the wavelength of the fluorescence detector to an excitation wavelength of 265 nm and a fluorescence wavelength of 269 nm. .

In other words, by setting the wavelength of the fluorescence detector under these conditions, it is possible to detect target monocyclic aromatic hydrocarbons such as BTX among the many complex compounds found in circulating mud, cuttings, or crude oil. , is performed selectively compared to when performed at other wavelengths, and therefore,
The chromatogram is simplified and measurements can be performed in relatively short cycles.

For example, a length of 15 mm filled with a filler with an average particle size of 5 μm
If a cm separation column is used, one analysis can be completed in about 5 to 10 minutes. Usually, the drilling speed of an oil well is 0.1 to 1 m/min, so in this case, data can be obtained at every drilling depth of 0.5 to 10 m. Based on the BTX concentration at each depth obtained in this manner, a change diagram is created, and the presence or absence of oil signs is determined from this diagram.

Next, an overview of the analysis operation will be explained.

A methanol/water mixture obtained by collecting circulating mud water of 1 to 5 m+Q, preferably 3+nQ from a well drilling site and placing it in a suitable container with a lid having a capacity of 10 to 20 mQ, and mixing this in a volume ratio of 85/15. Dilute with a solvent to 3-15 mu, preferably 10 mQ. In the case of cuttings, 1 to 5 g, preferably 3 g, are collected from the well drilling site, placed in a container with a lid, as in the case of circulating mud, and 3 to 15 mQ1, preferably 10 mR of a methanol/water mixed solvent is added. After closing the lid, shake it by hand or with a suitable device for several minutes to extract the components in the circulating slurry or cuttings. Suck up the supernatant liquid as it is or let it stand for several minutes and separate it with a syringe, filter it using filter paper or a glass filter, remove the solid content, and use it as a sample to be injected into the 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.

Solids can also be removed by centrifugation instead of filtration. In the case of circulating mud, the collected sample is mixed with methanol and
Without diluting with a water mixed solvent, 5 to 15 mQ, preferably 10 mQ of the mixture can be directly applied to a centrifuge to separate the solid content.

In a liquid chromatograph, methanol and water are mixed at a concentration of 9515 to 60/401, preferably 85, prior to sample injection.
The eluent prepared by mixing at a volume ratio of /15 is allowed to flow through the packing packed in the separation column at a flow rate of 0.5 to 3 mQ1 minute, preferably 1 to 1.5 mf/min. The liquid containing the sample is sucked up with a microsyringe with a volume of 10 to 50μ, and a certain amount of the sample is injected into the divided columns of the liquid chromatograph.

You can read the injection amount on the scale on the microsyringe, or
It may be injected using a loop (stainless steel tube with constant metering).

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

Detection and quantitative determination of benzene, toluene, and xylenes are performed at regular intervals according to the excavation depth, and the presence of crude oil or the like underground is detected from changes in their concentrations.

The above operations from pretreatment to analysis may be performed manually for one sample, or pretreatment of some samples may be performed manually and analysis automatically performed using an autosampler.

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

In Fig. 2, circulating mud is pumped from excavation site 16 to pump 1.
7 continuously to a mixer 18. On the other hand, the diluent stored in the diluent tank 19 is supplied to the mixer 18 at a constant flow rate by a pump 20. mixer 18
The diluted and mixed circulating mud water is sent to a solid separation device 21 such as a filtration device or a centrifugal separator. The sample, such as the filtrate or centrifuged liquid from which the solid matter has been separated, is sent to the sample injection device 3 of the liquid chromatography.

The eluent is sent to the sample injection device 3 by the pump 2 from the eluent tank 1, as in the case of FIG. 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 an eluent as required. Injection of the sample into the separation column 4 is performed by automatically switching the switching cock of the sample injection device 3 using a timer 22 or the like depending on the measurement time. The sample leaving the solid matter separator 21 is sent to the waste liquid tank 23 until the next analysis is performed.

〔Example〕

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

Example 1 3 mQ of muddy water collected at a well drilling site was put into a container with a capacity of about 20 mQ, and methanol and water (volume mixing ratio: 85
Add 10mQ of /15), shake several times, and add about 3m of
Q was filtered through a 0.45μ filter paper, and the obtained filtrate was filtered using a fluorescence detector as the detector 6 in the liquid chromatography shown in FIG. Diameter 4.6mm, length 2
Using a separation column packed in a 0 cm stainless steel tube, the excitation wavelength of the fluorescence detector was set to 265 nm and the fluorescence wavelength was set to 269 nm.
It was analyzed as m. As an eluent, methanol/water (
A volume mixing ratio of 85/15) was used, and the flow rate was 1 m2/min. The analysis results are shown in Figure 3. According to the results of this analysis, aromatic compounds such as toluene and xylene are detected, which indicates the presence of an oil layer.

Example 2 In an oil drilling well, toluene and m-xylene concentrations in circulating mud were analyzed every 10 m from a drilling depth of 2100 to 2540 m under the same conditions as in Example 1. The result is the 4th drawing.

Shown in ■.

The toluene and m-xylene concentrations in the circulating mud are 22
It can be seen that the concentrations of these compounds were below the detection limit up to 10 m, but increased at depths deeper than 2220 m. Based on the results of electrical logging and several other physical methods conducted after the completion of excavation, Fig. 4.
As shown in 231O to 2360 (A layer), 2372
The layers ~2407m (B layer), 2418-2468 (C layer) and 2481-2502m (D layer) were completed as productionable layers. When performing this finishing,
For example, a casing pipe connected to a perforated pipe is inserted into a wellbore, the perforated pipe is positioned in a sampling layer, and then a hardening material such as cement is applied between the wellbore circumferential wall and the casing pipe in the upper part of the sampling layer. Fill the material.

Next, a production test was conducted on each of these finished layers, and as a result, it was confirmed that both gas and condensate were produced from each layer. 4th drawing.

As shown in ■, when the depth is deeper than 2220m,
The concentrations of toluene and m-xylene show an increasing trend, which corresponds to the presence of condensate.

Comparative Example In the same well as in Example 2, mud gas separated from mud water was analyzed at 1-5 m intervals by conventional gas chromatography. Figure 4 I shows the resulting total mud gas (total amount of gaseous hydrocarbons analyzed by gas chromatography, indicated as TMG in Figure 4) and changes in the concentration of methane gas in the total mud gas.
Shown in II and IV.

In the change diagram of total mud gas (TMG) and methane,
Although some notable peaks were observed up to an excavation depth of 2210 m, toluene and m-xylene were not detected at all up to this depth. Therefore, it is expected that the geological formations in this area contain gas mainly composed of methane, but not condensate or crude oil.

On the other hand, in geological formations deeper than 2220 m, peaks appear continuously in the total mud gas (TMG) and methane change diagrams, and peaks also appear in the toluene and m-xylene change diagrams. This indicates that condensate or crude oil may be present along with gas in these formations.

In this way, with conventional gas chromatography, it is possible to know the presence of gas such as methane in a geological formation during the drilling process, but it is difficult to know whether condensate or crude oil is present. This method is possible and provides useful information when drilling oil wells.

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

By analyzing circulating mud or cuttings at an oil well drilling site after a relatively simple pretreatment, we determined that benzene, which is commonly found in crude oil but not found in mud materials, was detected. , toluene, and xylenes, and quantify them, making it possible to detect the presence of an oil layer more directly and quickly than with conventional methods. Also, compared to the fluorescence reaction method, there are no individual differences in the judgment of results,
Moreover, there is no need to worry about contamination by petroleum-based muddy water materials, and it is possible to clearly detect oil layers. Furthermore, by automating the operation, it can become a new mud logging method that replaces the gas chromatograph measurement method of mud gas, making a major contribution to the field of oil exploration.

[Brief explanation of the drawing]

Figure 1 shows the configuration of liquid chromatography, Figure 2 shows the configuration of liquid chromatography.
The figure shows the configuration of a liquid chromatography system equipped with an automatic sample pretreatment device, Figure 3 shows a liquid chromatogram of circulating mud, and Figure 4 shows the drilling depth of the well and toluene and toluene in the circulating mud. It is a figure showing the relationship with the 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 processing device, F is a pump, 18 is a mixer, 1
9 is a diluent tank, 20 is a diluent pump, -. is solid matter separator, 22 is timer

Claims (3)

[Claims] (1) At the drilling site of an oil well, circulating mud or cuttings are collected and analyzed by liquid chromatography, and all or An oil signature identification method that detects the presence of crude oil or gas condensate by detecting any one or more of these components. (2) The oil signature identification method according to claim 1, wherein a fluorescence detector is used as the liquid chromatography detector. (3) The oil signature identification method according to claim 1 or 2, wherein operations from sampling the circulating mud to measurement by liquid chromatography are automatically performed.