Three-dimensional quantitative fluorescent logging method
By using a three-dimensional quantitative fluorescence logging method, fluorescence data from solid and liquid samples are acquired and processed. The combined data are used to calculate oil concentration and correlation grade, and to identify reservoir fluid properties. This method solves the accuracy and subjectivity problems of traditional logging techniques and achieves high-precision reservoir analysis.
Patent Information
- Application Number
- CN202511684886.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-17
- Publication Date
- 2026-03-20
AI Technical Summary
Traditional logging techniques are inadequate for identifying reservoir fluid properties. Cuttings logging is highly subjective, gas logging cannot accurately analyze the oil content of liquid samples, and geophysical logging is not direct or accurate enough in complex geological conditions, making it difficult to meet the requirements of high-precision logging.
The three-dimensional quantitative fluorescence logging method is used to obtain solid and liquid samples, perform preprocessing and mathematical statistics, obtain fluorescence data, combine and calculate oil concentration and correlation grade, determine crude oil properties and calculate oiliness index, and finally identify reservoir fluid properties.
It improves the accuracy and reliability of logging results, enabling more precise analysis of reservoir oil content and crude oil properties, avoiding the subjectivity problems of traditional methods, and achieving comprehensive analysis of liquid samples.
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Figure CN121702818A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application relates to the technical field of oil exploration, in particular to a three-dimensional quantitative fluorescence logging method. BACKGROUND
[0002] In the field of oil exploration, logging technology is a key technology, which has important significance for understanding the conditions of underground oil and gas layers, evaluating oil and gas resource reserves, etc. With the continuous advancement of oil exploration work to more complex geological environments, higher requirements are put forward for the accuracy and efficiency of logging technology. Accurate logging results can provide reliable basis for subsequent exploitation work, help to improve the success rate and economic benefits of oil exploitation, and promote the development of the entire oil industry.
[0003] In traditional logging work, in order to identify the properties of reservoir fluids, some conventional means are usually used. One common method is rock debris logging, which mainly relies on observation and analysis of the appearance characteristics of rock debris, core and other samples, such as the color, structure and structure of the rock, to infer the underground geological conditions and the properties of reservoir fluids. There is also a gas logging method, which detects the composition and content of the gas returned during drilling to determine whether there is an oil and gas layer and the general properties of the oil and gas. In addition, geophysical logging is also one of the commonly used means, which uses various geophysical instruments to measure the physical properties of the rock around the well hole, such as resistivity and acoustic velocity, to infer the properties of the reservoir and the fluid conditions.
[0004] However, rock debris logging mainly relies on manual observation and experience, which is highly subjective, and it is difficult to accurately grasp some subtle characteristics, which may lead to incorrect judgments. Gas logging can only detect gas information and cannot accurately analyze the oil content in liquid samples. Although geophysical logging can provide some physical property data, it is not direct and accurate enough for the judgment of reservoir fluid properties under complex geological conditions, and it is difficult to meet the current demand for high-precision logging in oil exploration. SUMMARY
[0005] In order to overcome the above technical problems, the application provides a three-dimensional quantitative fluorescence logging method.
[0006] The three-dimensional quantitative fluorescence logging method provided by the application adopts the following technical scheme: A three-dimensional quantitative fluorescence logging method, comprising the following steps S1, obtaining solid samples and liquid samples; S2, pretreatment of solid samples and liquid samples; S3, obtaining fluorescence data of solid samples and liquid samples after mathematical statistics; S4, calculating the oil concentration and contrast grade by combining the fluorescence data; S5, judging the crude oil property and calculating the oiliness index; S6, identifying the reservoir fluid property according to the oiliness index and the contrast grade parameter.
[0007] By adopting the technical scheme, solid and liquid samples are obtained, fluorescence data are obtained through pretreatment and mathematical statistics, oil concentration and contrast grade are obtained through combination calculation, the crude oil property is judged and the oiliness index is calculated, and finally the reservoir fluid property is identified according to the oiliness index and the contrast grade parameter, so that the oil-bearing condition and the crude oil property of the reservoir can be accurately analyzed and the reservoir fluid property can be effectively identified.
[0008] Optionally, in the S1, the solid sample includes well wall coring, drilling coring and rock debris, and the liquid sample includes drilling fluid.
[0009] By adopting the technical scheme, the specific types of the solid sample and the liquid sample are determined, which provides a more accurate sample basis for subsequent accurate acquisition of fluorescence data, calculation of oil concentration and contrast grade, judgment of crude oil property, calculation of oiliness index and identification of reservoir fluid property, and helps to improve the accuracy and reliability of the three-dimensional quantitative fluorescence logging method.
[0010] Optionally, in the S2, the pretreatment of the solid sample includes sample rinsing, drying with filter paper after rinsing, grinding into powder after drying, and putting 1g of the powdered sample into a stoppered test tube, adding 5ml of n-ethane for soaking for at least 5 minutes to obtain a solid sample solution.
[0011] By adopting the technical scheme, the hydrocarbon substances in the solid sample are better dissolved in n-ethane through rinsing, drying, grinding and soaking of the solid sample, so that the solid sample solution is obtained, and a foundation is laid for subsequent accurate acquisition of fluorescence data.
[0012] Optionally, in the S2, the pretreatment of the solid sample solution and the liquid sample includes selecting a dilution multiple n, keeping the concentration of the solid sample solution after re-dilution or the concentration of the liquid sample after dilution below 40mg / L, determining the volume V2 of the final dilute solution according to the volume of the instrument cuvette, calculating the volume V1 of the concentrated solution to be taken, the calculation formula is V1=V2 / N*1000, wherein V1 is the volume of the concentrated solution to be taken, in units of uL, V2 is the volume of the dilute solution, in units of mL, n is the dilution multiple; The diluted dilute solution is observed, if the liquid is colorless and transparent, the sample to be measured can be taken to the next step, if the liquid has color, the step S2 needs to be performed again and a new dilution multiple n is selected for re-dilution until the liquid is colorless and transparent.
[0013] By adopting the above technical scheme, the concentration of the solid sample solution after re-dilution or the concentration of the liquid sample after dilution is kept below 40 mg / L, the sample concentration is within the linear response range of the testing instrument, the accuracy of subsequent fluorescence data acquisition and analysis is ensured, the diluted dilute solution is observed, if the liquid is colorless and transparent, the sample to be measured can be subjected to the next step, if the liquid has color, the subsequent fluorescence data acquisition will be affected, and the sample needs to be re-diluted until colorless and transparent, and the sample is further ensured to meet the testing requirements.
[0014] Optionally, the specific steps of acquiring fluorescence data in S3 include: putting the sample to be measured obtained in S2 into an instrument cuvette as a measured sample, scanning the measured sample by using a fluorescence spectrometer, the fluorescence wavelength scanning range is that an excitation wavelength (Ex) continuously acts on the measured sample from 200 nm to 800 nm, the fluorescence intensity of an emission wavelength (Em) of 200 nm to 800 nm is received by the fluorescence analyzer, and the highest peak value of the light emitted by the hydrocarbon substance in the measured sample, that is, the fluorescence intensity (F), is recorded, if the fluorescence intensity (F) exceeds 800 or is lower than 300, the sample needs to be re-selected in S2 for pretreatment until the fluorescence intensity (F) is between 300 and 800.
[0015] By adopting the above technical scheme, the treated sample to be measured is put into an instrument cuvette, the fluorescence spectrometer is used to continuously act on the measured sample at an excitation wavelength of 200 nm to 800 nm, the light intensity emitted by the hydrocarbon substance at an emission wavelength of 200 nm to 800 nm is received and the highest peak value is recorded, if the fluorescence peak is abnormal, the sample is re-pretreated, the fluorescence data after mathematical statistics can be accurately acquired, the data is ensured to be within a suitable range, the excitation wavelength (Ex) and the emission wavelength (Em) are taken as horizontal and vertical coordinates, and the fluorescence intensity (F) is taken as vertical coordinate to draw a three-dimensional model, which provides a reliable basis for subsequent calculation of oil concentration, comparison level, judgment of crude oil properties, calculation of oil index and identification of reservoir fluid properties.
[0016] Optionally, the specific steps of combination calculation in S4 include: calculating the oil concentration (C), that is, the content of the hydrocarbon substance in the unit measured sample, The calculation formula is C=(K·F+b)×n, in the formula, C is the oil concentration of the measured sample, the unit is mg / L, K and b are instrument calibration coefficients, F is the fluorescence intensity value, n is the dilution multiple; calculating the comparison level (N), that is, the oil level of the hydrocarbon substance in the unit sample, The calculation formula is N=15-(4-lgC) / 0.301, in the formula, N is the comparison level of the measured sample, C is the oil concentration of the measured sample.
[0017] By adopting the technical scheme, after obtaining the fluorescence data, the oil content and the contrast level are calculated by combination calculation, and the content of the hydrocarbon material in the unit measured sample and the oil content level can be accurately determined.
[0018] Optionally, in S5, the properties of the crude oil are judged according to the peak position of the fluorescence wavelength according to the regional interpretation standard, the oiliness index (Oc) is calculated after the properties of the crude oil are judged, that is, the ratio of the maximum fluorescence intensity of the medium oil peak to the maximum fluorescence intensity of the light oil peak, The calculation formula is Oc=F2 / F1, wherein Oc is the oiliness index of the measured sample, F2 is the maximum fluorescence intensity value of the medium oil in the measured sample, F1 is the maximum fluorescence intensity value of the light oil in the measured sample.
[0019] By adopting the technical scheme, the peak position of the three-dimensional model is referred to, the properties of the crude oil are judged according to the regional interpretation standard, the calculated oiliness index can provide an important parameter for subsequent identification of the properties of the reservoir fluid, and the reservoir condition can be more accurately analyzed.
[0020] Optionally, the identification basis of the properties of the reservoir fluid in S6 is that The gas layer: with the increase of the well depth, the contrast level fluctuates uniformly, the maximum value of the contrast level is greater than 6, the oiliness index fluctuates stably and is less than 1; The oil layer: with the increase of the well depth, the contrast level presents a growth trend, the main part of the contrast level is greater than 6, the oiliness index fluctuates uniformly, and the main part is greater than 1; The oil-water layer: with the increase of the well depth, the contrast level presents a decreasing trend, the main part of the contrast level is greater than 5, and the oiliness index presents a growth trend; The water layer and the dry layer: with the increase of the well depth, the contrast level fluctuates unevenly, and the main part of the contrast level is less than 6.
[0021] By adopting the technical scheme, the gas layer, the oil layer, the oil-water layer and the water layer and the dry layer and other different reservoir fluid properties can be accurately and carefully identified according to the change characteristics of the contrast level and the oiliness index with the well depth.
[0022] Optionally, in S6, the identification basis of the properties of the reservoir fluid is that a two-dimensional interpretation chart with the oiliness index as the vertical coordinate and the contrast level as the horizontal coordinate is established, the fluorescence analysis data of the tested well section are plotted into the two-dimensional interpretation chart, the two-dimensional interpretation chart is divided into a water layer and a dry layer area, an oil layer area and a gas layer area according to the distribution of the data of different fluid properties of the reservoir in the two-dimensional interpretation chart, the data of the measured sample are plotted into the two-dimensional interpretation chart, and the properties of the reservoir fluid are judged according to the area where the measured sample falls.
[0023] By adopting the above technical solution, the fluorescence analysis data of the tested well section can be displayed and partitioned using a two-dimensional interpretation chart. This allows for a more intuitive judgment of the reservoir fluid properties based on the area where the tested sample falls on the chart, thereby improving the accuracy and efficiency of the judgment.
[0024] In summary, this application includes at least one of the following beneficial technical effects: 1. By performing pretreatment, acquiring fluorescence data, and combining calculations on solid and liquid samples, the oil concentration and correlation grade can be accurately determined, thus improving the accuracy of logging results; 2. The properties of crude oil are determined by the peak position of the fluorescence wavelength and the oiliness index is calculated. Combined with the parameters of the comparison stage, the properties of reservoir fluids are identified, avoiding the subjective problem of traditional cuttings logging relying on manual observation and experience. 3. This method can process both solid and liquid samples simultaneously, solving the problem that traditional gas logging can only detect gas information and cannot accurately analyze the oil content of liquid samples, thus enabling more comprehensive logging analysis. Attached Figure Description
[0025] Figure 1 This is a flowchart of the three-dimensional quantitative fluorescence logging method provided in the embodiments of this application.
[0026] Figure 2 This is a two-dimensional explanatory diagram provided in the embodiments of this application. Detailed Implementation
[0027] The following is in conjunction with the appendix Figures 1-2 This application will be described in further detail.
[0028] This application discloses a three-dimensional quantitative fluorescence logging method.
[0029] like Figure 1 As shown, the three-dimensional quantitative fluorescence logging method includes the following steps.
[0030] S1, Obtain solid and liquid samples.
[0031] Solid samples include wellbore cores, drilling cores, and cuttings; liquid samples include drilling fluid.
[0032] Before drilling begins, take at least two drilling fluid samples; during drilling, take at least one drilling fluid sample every 100m of drilling.
[0033] In the target layer, cuttings should be sampled according to the cuttings logging interval. If no cuttings are found in the target layer, drilling fluid samples should be taken according to the cuttings logging interval. In non-target layers, cuttings should be sampled according to the cuttings logging interval for reservoirs and for non-reservoir layers, samples should be taken for each layer. When the thickness is greater than 5m, at least one sample should be taken every 5m.
[0034] The core sampler is used to continuously extract cores from the bottom of the wellbore.
[0035] When coring, at least one sample should be taken every 10 cm in the reservoir and at least one sample should be taken every 20 cm in the non-reservoir area.
[0036] S2, Pretreatment of solid and liquid samples.
[0037] The pretreatment of solid samples includes rinsing the sample, drying it by blotting with filter paper, grinding it into powder, taking 1g of powdered solid sample with a balance and putting it into a stoppered test tube, adding 5ml of n-hexane and soaking for at least 5 minutes to obtain a solid sample solution.
[0038] Pretreatment of solid and liquid samples includes selecting a dilution factor n to maintain the concentration of the diluted solid sample solution or liquid sample below 40 mg / L, determining the final volume V2 of the diluted solution based on the volume of the instrument's cuvette, and calculating the volume V1 of the concentrated solution to be obtained. The calculation formula is V1 = V2 / N × 1000, where V1 is the volume of the concentrated solution to be collected in microliters (µL). V2 is the volume of a dilute solution, expressed in mL (milliliters). n is the dilution factor; Observe the diluted solution. If the liquid is colorless and transparent, the sample is ready for the next step. If the liquid is colored, step S2 needs to be repeated, and a new dilution factor n needs to be selected to dilute it again until the liquid is colorless and transparent. Table 1 shows the selectable range of dilution factors.
[0039] Table 1. Selectable range of dilution factors S3, acquire fluorescence data of solid and liquid samples after mathematical statistics.
[0040] The sample obtained in step S2 is placed in the instrument's cuvette. A fluorescence spectrometer is used to scan the sample, with the fluorescence wavelength scanning range being the excitation wavelength (Ex) continuously applied to the sample from 200 nm to 800 nm. The fluorescence analyzer receives the fluorescence intensity from the emission wavelength (Em) from 200 nm to 800 nm and records the highest peak value of the light emitted by hydrocarbon substances in the sample, i.e., the fluorescence intensity (F). If the fluorescence intensity (F) exceeds 800, it is necessary to return to step S2 and reselect n for preprocessing until the fluorescence intensity (F) is below 800. A three-dimensional model is plotted using the excitation wavelength (Ex) and emission wavelength (Em) as the horizontal and vertical axes, and the fluorescence intensity (F) as the vertical axis.
[0041] S4, the oil concentration and contrast grade are obtained by combining and calculating the fluorescence data.
[0042] The specific steps of the combined calculation include calculating the oil concentration (C), which is the content of hydrocarbons in a unit of the sample being tested. The calculation formula is C = (K·F + b) × n, where C is the oil concentration of the sample being tested, in mg / L. K and b are instrument calibration coefficients. F represents the fluorescence intensity value. n is the dilution factor; Calculate the comparison grade (N), which is the oil content level of hydrocarbons per unit sample. The calculation formula is N = 15 - (4 - lgC) / 0.301, where N is the comparison grade of the sample being tested. C represents the oil concentration of the sample being tested.
[0043] S5, determine the properties of crude oil and calculate the oiliness index.
[0044] The properties of crude oil were determined by combining the peak positions of fluorescence wavelengths from the three-dimensional model with regional interpretation standards. Table 2 shows the interpretation standards for the classification of crude oil properties in the Bohai region using three-dimensional quantitative fluorescence. Table 2. Interpretation Standards for the Classification of Crude Oil Properties in the Bohai Region using Three-Dimensional Quantitative Fluorescence After determining the properties of the crude oil, the oiliness index (Oc) is calculated, which is the ratio of the highest fluorescence intensity of the medium-quality oil peak to the highest fluorescence intensity of the light-quality oil peak. The calculation formula is Oc = F2 / F1, where Oc is the oiliness index of the sample being tested. F2 is the maximum fluorescence intensity value of the oil in the tested sample. F1 represents the maximum fluorescence intensity value of the light oil sample being tested.
[0045] S6 identifies reservoir fluid properties based on the oiliness index and correlation parameters.
[0046] The embodiments of this application provide two interpretation methods.
[0047] Fluid properties can be determined based on data that varies with well depth. The identification criteria are as follows: Gas layer: With increasing well depth, the relative grade fluctuates uniformly, and the maximum value of the relative grade is greater than 6. The oiliness index fluctuates stably and is less than 1. Oil layer: With the increase of well depth, the relative grade shows an increasing trend, with the majority of relative grades being greater than 6, and the oiliness index fluctuates evenly, with the majority being greater than 1; Oil-water co-containment: As well depth increases, the relative grade shows a decreasing trend, the relative grade is generally greater than 5, and the oiliness index shows an increasing trend; Water layer and dry layer: As well depth increases, the correlation grade fluctuates unevenly, with the main correlation grade being less than 6.
[0048] It is possible Figure 2 A two-dimensional interpretation chart is established with the oiliness index on the vertical axis and the comparison grade on the horizontal axis. Fluorescence analysis data of the tested well sections are plotted on the two-dimensional interpretation chart. Based on the distribution of data of reservoirs with different fluid properties on the two-dimensional interpretation chart, the two-dimensional interpretation chart is divided into water-bearing dry zone, oil-bearing zone, and gas-bearing zone. Data of the tested samples are plotted on the two-dimensional interpretation chart. The reservoir fluid properties are determined based on the area where the tested samples fall.
[0049] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.
Claims
1. A three-dimensional quantitative fluorescence logging method, characterized in that, Includes the following steps: S1, Obtain solid and liquid samples; S2, Pretreatment of solid and liquid samples; S3, acquire fluorescence data of solid and liquid samples after mathematical statistics; S4, the oil concentration and contrast grade are obtained by combining and calculating the fluorescence data; S5, determine the properties of crude oil and calculate the oiliness index; S6 identifies reservoir fluid properties based on the oiliness index and correlation parameters.
2. The three-dimensional quantitative fluorescence logging method according to claim 1, characterized in that, In S1, the solid sample includes wellbore core, drilling core and rock cuttings, and the liquid sample includes drilling fluid.
3. The three-dimensional quantitative fluorescence logging method according to claim 2, characterized in that, In step S2, the pretreatment of the solid sample includes rinsing the sample, drying it with filter paper after rinsing, grinding it into powder after drying, taking 1g of powder sample and placing it into a stoppered test tube, adding 5ml of n-hexane and soaking it for at least 5 minutes to obtain a solid sample solution.
4. The three-dimensional quantitative fluorescence logging method according to claim 3, characterized in that, In step S2, the pretreatment of solid and liquid sample solutions includes selecting a dilution factor n to keep the concentration of the diluted solid sample solution or the diluted liquid sample below 40 mg / L, determining the final volume V2 of the diluted solution based on the volume of the instrument's cuvette, and calculating the volume V1 of the concentrated solution to be obtained. The calculation formula is V1 = V2 / N × 1000, where V1 represents the volume of the concentrated solution to be collected, in microliters (µL). V2 is the volume of a dilute solution, expressed in mL (milliliters). n is the dilution factor; Observe the diluted solution. If the liquid is colorless and transparent, the sample to be tested is obtained and the next step can be carried out. If the liquid has color, step S2 needs to be repeated and a new dilution factor n needs to be selected to dilute it again until the liquid is colorless and transparent.
5. The three-dimensional quantitative fluorescence logging method according to claim 4, characterized in that, The specific steps for obtaining fluorescence data in S3 include placing the sample to be tested obtained in S2 into a cuvette of the instrument, scanning the sample using a fluorescence spectrometer, and continuously applying the fluorescence wavelength scan range from the excitation wavelength (Ex) to the sample from 200 nm to 800 nm. The fluorescence analyzer receives the fluorescence intensity from the emission wavelength (Em) from 200 nm to 800 nm and records the highest peak value of the light emitted by the hydrocarbon substances in the sample, i.e., the fluorescence intensity (F). If the fluorescence intensity (F) exceeds 800 or is lower than 300, it is necessary to return to S2 and reselect n for preprocessing until the fluorescence intensity (F) is between 300 and 800.
6. The three-dimensional quantitative fluorescence logging method according to claim 5, characterized in that, The specific steps of the combined calculation in S4 include calculating the oil concentration (C), which is the content of hydrocarbons per unit of the sample being tested. The calculation formula is C = (K·F + b) × n, where C represents the oil concentration of the sample being tested, in mg / L. K and b are instrument calibration coefficients. F represents the fluorescence intensity value. n is the dilution factor; Calculate the comparison grade (N), which is the oil content level of hydrocarbons per unit sample. The calculation formula is N=15-(4-lgC) / 0.301, where N represents the comparison level of the sample being tested. C represents the oil concentration of the sample being tested.
7. The three-dimensional quantitative fluorescence logging method according to claim 6, characterized in that, In step S5, the properties of crude oil are determined based on the peak position of the fluorescence wavelength according to the regional interpretation standard. After determining the properties of crude oil, the oiliness index (Oc) is calculated, which is the ratio of the highest fluorescence intensity of the medium oil peak to the highest fluorescence intensity of the light oil peak. The calculation formula is Oc = F2 / F1, where Oc is the oiliness index of the sample being tested. F2 is the maximum fluorescence intensity value of the oil in the tested sample. F1 represents the maximum fluorescence intensity value of the light oil sample being tested.
8. The three-dimensional quantitative fluorescence logging method according to claim 7, characterized in that, The identification criteria for reservoir fluid properties in S6 are as follows: Gas layer: With increasing well depth, the relative grade fluctuates uniformly, and the maximum value of the relative grade is greater than 6. The oiliness index fluctuates stably and is less than 1. Oil layer: With the increase of well depth, the relative grade shows an increasing trend, with the majority of relative grades being greater than 6, and the oiliness index fluctuates evenly, with the majority being greater than 1; Oil-water co-containment: As well depth increases, the relative grade shows a decreasing trend, the relative grade is generally greater than 5, and the oiliness index shows an increasing trend; Water layer and dry layer: As well depth increases, the correlation grade fluctuates unevenly, with the main correlation grade being less than 6.
9. The three-dimensional quantitative fluorescence logging method according to claim 7, characterized in that, The identification of reservoir fluid properties in S6 is based on establishing a two-dimensional interpretation chart with oiliness index on the vertical axis and comparison grade on the horizontal axis. Fluorescence analysis data of the tested well sections are plotted on the two-dimensional interpretation chart. According to the distribution of data of reservoirs with different fluid properties on the two-dimensional interpretation chart, the two-dimensional interpretation chart is divided into water-bearing dry zone, oil-bearing zone, and gas-bearing zone. The data of the tested sample are plotted on the two-dimensional interpretation chart. The reservoir fluid properties are determined according to the area where the tested sample falls.