Oil-based logging three-dimensional quantitative fluorescence reservoir oil and gas evaluation method

Abstract

This invention relates to the field of oil and gas logging technology, and provides a three-dimensional quantitative fluorescence method for evaluating reservoir oil and gas in oil-based logging. The method comprises the following steps: Step S1, taking cuttings samples from the target formation of the oil well under oil-based drilling fluid conditions, and cleaning and drying the samples; Step S2, weighing 0.01g to 0.05g of cuttings samples, and using a three-dimensional fluorescence spectrometer to detect and analyze the samples, collecting spectra and detection data; Step S3, inputting the excitation wavelength, emission wavelength, and corresponding oil content data of the main peaks of the background and reservoir cuttings into a three-dimensional coordinate space to obtain a three-dimensional fluorescence data projection map of the background and reservoir cuttings. This invention establishes a three-dimensional quantitative fluorescence method for evaluating reservoir oil and gas contaminated by oil-based drilling fluid, reducing the impact of oil-based drilling fluid on oil and gas evaluation from the source of analysis. The method is convenient and effective, enriching the interpretation means of oil-based logging.

Description

Technical Field

[0001] This invention relates to the field of oil and gas logging technology, and is a three-dimensional quantitative fluorescence reservoir oil and gas evaluation method based on oil-based logging. Background Technology

[0002] Oil-based logging refers to logging technology under oil-based drilling fluid conditions. Existing oil-based logging reservoir oil-bearing interpretation and evaluation technologies mainly rely on gas logging, geochemical three-dimensional quantitative fluorescence, etc.

[0003] Oil-based drilling fluids offer advantages over water-based fluids, including high-temperature resistance, reservoir protection, resistance to salt and calcium intrusion, wellbore stabilization, and good lubrication. Therefore, they are widely used in high-risk drilling processes such as deep wells, ultra-deep wells, shale oil and gas wells, gypsum-rich formations, and easily collapsible mudstone formations, achieving faster and more efficient drilling. However, the dissolved gas logging components (white oil or diesel oil) in oil-based drilling fluids can adhere to the cuttings surface, contaminating cuttings samples and making them difficult to clean. This severely affects the accuracy of logging data acquisition and analysis, including gas logging, cuttings logging, and geochemical logging, leading to difficulties in interpreting reservoir oil content. To address this, previous researchers have developed corresponding logging interpretation methods, among which two typical types are: gas logging and three-dimensional quantitative fluorescence logging.

[0004] Gas logging identifies true and false gas shows by analyzing the differences in the content of total hydrocarbons and methane in oil-based drilling fluids. For example, in the Sichuan Basin, white oil-based drilling fluids show significant differences in total hydrocarbons and C1 in well sections without oil and gas shows, but in well sections with oil and gas shows, the correlation between total hydrocarbons and components is better and the curve shape tends to be consistent. In addition, formation gas content and gas filling coefficient, which are less affected by oil-based drilling fluids, can be selected to establish a method for identifying oil, gas and water layers and an interpretation and evaluation chart. Yang Lin et al. (The Influence and Understanding of White Oil-Based Drilling Fluids on Gas Logging Data [J]. Logging Engineering, 2020, 31(4): 10-15.) analyzed the causes of the characteristics of gas logging data of white oil-based drilling fluids from the aspects of gas chromatography, white oil properties, bottom hole temperature and drilling conditions. Gas logging interpretation is of great significance in the field of oil and gas discovery, but it is greatly affected by the logging environment. Influencing factors include the type of oil-based drilling fluid, drilling fluid performance, underbalanced drilling, gas chromatography instrument model, degasser efficiency, etc., which makes the accuracy of gas logging measurement interpretation low.

[0005] Three-dimensional quantitative fluorescence logging (3D-QFLAR) can experimentally analyze the oil content of cuttings samples with high sensitivity, detecting even very small amounts of oil, with a minimum detection concentration of 0.01 mg / L. Essentially, the crude oil components (mixed compounds) in cuttings differ from the white oil or diesel components (single compounds) in oil-based drilling fluids. This difference is reflected in the main peak positions on the 3D-QFLAR spectrum, which is the fundamental principle of oil and gas discovery and evaluation. Based on this principle, mixtures of oil-based drilling fluid and crude oil samples in different proportions are prepared experimentally, and their spectra are analyzed to establish an original spectral library. The similarity of the spectrum of the sample to be analyzed with the original spectral library is then compared to determine the true oil content of the sample. Chinese invention patent CN105092547B discloses a fluorescence analysis method for mixed samples based on spectral morphology. In the fluorescence analysis of the influence of oil-based drilling mud from oilfield logging, an original spectral library is established by combining oil-based drilling mud spectra with crude oil sample spectra. A mixed spectral library is obtained by mixing sub-spectrums of oil-based drilling mud and crude oil samples in different proportions. The similarity of the spectrum of the oil-bearing sample to be analyzed with each mixed spectrum in the library is compared, and the influence of oil-based drilling mud is eliminated to obtain the original crude oil spectrum in the oil-bearing sample. However, the original spectral library of mixed oil-based drilling fluid and crude oil samples established based on experimental methods is incomplete due to factors such as the type of oil-based drilling fluid and the complexity of crude oil properties in different regions. This results in a huge workload and is not conducive to the timeliness requirements of oil and gas exploration and evaluation. Summary of the Invention

[0006] This invention provides a three-dimensional quantitative fluorescence reservoir oil and gas evaluation method based on oil-based logging, which overcomes the shortcomings of the prior art. It can effectively solve the problem that white oil or diesel oil in oil-based drilling fluid adheres to the surface of rock cuttings and cannot be completely removed, resulting in distortion of geochemical three-dimensional quantitative fluorescence data and spectra, making oil and gas interpretation and evaluation difficult.

[0007] The technical solution of this invention is achieved through the following measures: a three-dimensional quantitative fluorescence reservoir oil and gas evaluation method based on oil-based logging, comprising the following steps:

[0008] Step S1: Take rock cuttings samples from the target formation of the oil well under oil-based drilling fluid conditions, and clean and dry the rock cuttings samples; the rock cuttings samples include background rock cuttings and reservoir rock cuttings;

[0009] Step S2: Weigh 0.01g to 0.05g of rock cuttings sample, and use a three-dimensional fluorescence spectrometer to detect and analyze the rock cuttings sample, and collect spectrum and detection data; the detection data includes the excitation wavelength, emission wavelength and equivalent oil content data corresponding to the main peak of the spectrum;

[0010] Step S3: Input the data corresponding to the three parameters of excitation wavelength, emission wavelength and equivalent oil content of the main peak of the background rock cuttings and reservoir rock cuttings into the three-dimensional coordinate space, and project them in the coordinate plane of excitation wavelength and emission wavelength to obtain the three-dimensional fluorescence data projection map of the background rock cuttings and reservoir rock cuttings, and qualitatively determine the authenticity of the oil and gas show in the reservoir.

[0011] The following are further optimizations and / or improvements to the above-mentioned technical solution:

[0012] The aforementioned three-dimensional quantitative fluorescence reservoir oil and gas evaluation method based on oil-based logging also includes:

[0013] Step S4: Using the three-dimensional quantitative fluorescence excitation wavelength, emission wavelength, and equivalent oil content data of the background rock fragment main peak as the reference point, and the three-dimensional quantitative fluorescence excitation wavelength, emission wavelength, and equivalent oil content data of the reservoir rock fragment main peak as the sample point, calculate the planar offset and vertical offset between the background rock fragment main peak and the reservoir rock fragment main peak.

[0014] Step S5: Using the well with known oil test results as the modeling well, the plane offset and vertical offset data of the sample points of the modeling well are intersected. Based on the trend of the sample landing points, the valuable layer and non-value layer are divided along the landing point boundary to obtain a quantitative plane offset and vertical offset interpretation model. The reservoir value of the oil well is evaluated using this model.

[0015] In step S1 above, the cleaning step for the rock cuttings sample is as follows: the rock cuttings sample is cleaned with an oil-based fluid containing the same components as the oil-based drilling fluid, and then the surface of the rock cuttings sample is rinsed with clean water to remove any floating oil.

[0016] In step S1 above, drying is performed by low-temperature drying using an electric baking plate or by air drying.

[0017] In step S1 above, the background rock fragments are mudstone rock fragments without oil and gas indications.

[0018] In step S1 above, the reservoir rock fragments are one or more of sandstone, carbonate rock, and igneous rock.

[0019] In step S4 above, the planar offset is calculated according to formula 1 below, and the vertical offset is calculated according to formula 2 below.

[0020]

[0021] |OV|=|z i -z0| Equation 2

[0022] in,

[0023] |OH| represents the plane offset.

[0024] |OV| represents the vertical offset.

[0025] x0, y0, z0 are the coordinates of the reference point in three-dimensional space.

[0026] x i y i , z i Let i be the coordinates of the sample point in three-dimensional space, i = 1, 2, ..., n, where n is the number of reservoir rock cuttings samples.

[0027] The present invention has the following advantages:

[0028] ①This invention improves the types of samples to be analyzed and reduces the impact of oil-based drilling fluids on the evaluation results.

[0029] ②The data processing method of this invention is simple and easy to operate. Without increasing the workload of analysis and testing, it improves the application and scope of three-dimensional quantitative fluorescence in oil-based logging.

[0030] ③ This invention combines qualitative and quantitative methods, which improves the accuracy of reservoir oil-bearing interpretation, enhances the applicability of three-dimensional quantitative fluorescence analysis, and is beneficial for oilfield testing, reservoir selection, and exploration and development decisions.

[0031] This invention improves the details of sample collection and analysis, and analyzes the changes in three parameters: three-dimensional quantitative fluorescence excitation wavelength, emission wavelength, and equivalent oil content. It establishes a three-dimensional quantitative fluorescence reservoir oil and gas evaluation method for oil-based drilling fluid contamination, which reduces the impact of oil-based drilling fluid on oil and gas evaluation from the source of analysis. The method is convenient and effective, enriches the means of oil-based logging interpretation, and the quantitative evaluation is flexible and easy to promote and apply. Attached Figure Description

[0032] Appendix Figure 1 This is an example of a three-dimensional quantitative fluorescence analysis spectrum of background rock cuttings under oil-based drilling fluid conditions according to the present invention.

[0033] Appendix Figure 2 This is an example of a three-dimensional quantitative fluorescence analysis spectrum of reservoir cuttings under oil-based drilling fluid conditions according to the present invention.

[0034] Appendix Figure 3 This is an example of a three-dimensional fluorescence data projection of background rock cuttings and reservoir rock cuttings for the present invention.

[0035] Appendix Figure 4 This is a three-dimensional fluorescence data projection of background rock cuttings and reservoir rock cuttings from Example 8.

[0036] Appendix Figure 5 This is the quantitative planar offset and vertical offset interpretation model for Example 8.

[0037] Appendix Figure 6 This is a schematic diagram illustrating the interpretation results of the quantitative planar offset and vertical offset of well H6 in Example 8. Detailed Implementation

[0038] This invention is not limited to the following embodiments; specific implementation methods can be determined based on the technical solution of this invention and actual circumstances. Unless otherwise specified, all chemical reagents and chemical products mentioned in this invention are well-known and commonly used chemical reagents and chemical products in the prior art.

[0039] The present invention will be further described below with reference to embodiments:

[0040] Example 1: The three-dimensional quantitative fluorescence reservoir oil and gas evaluation method based on oil-based logging is carried out according to the following steps:

[0041] Step S1: Take rock cuttings samples from the target formation of the oil well under oil-based drilling fluid conditions, and clean and dry the rock cuttings samples; the rock cuttings samples include background rock cuttings and reservoir rock cuttings;

[0042] Step S2: Weigh 0.01g to 0.05g of rock cuttings sample, and use a three-dimensional fluorescence spectrometer to detect and analyze the rock cuttings sample, and collect spectrum and detection data; the detection data includes the excitation wavelength (Em), emission wavelength (Ex) corresponding to the main peak of the spectrum, and the equivalent oil content data;

[0043] Step S3: Input the data corresponding to the three parameters of excitation wavelength, emission wavelength and equivalent oil content of the main peak of the background rock cuttings and reservoir rock cuttings into the three-dimensional coordinate space, and project them in the coordinate plane of excitation wavelength and emission wavelength to obtain the three-dimensional fluorescence data projection map of the background rock cuttings and reservoir rock cuttings, and qualitatively determine the authenticity of the oil and gas show in the reservoir.

[0044] Example 2: As an optimization of the above examples, the oil-based logging three-dimensional quantitative fluorescence reservoir oil and gas evaluation method further includes:

[0045] Step S4: Using the three-dimensional quantitative fluorescence excitation wavelength, emission wavelength, and equivalent oil content data of the background rock fragment main peak as the reference point, and the three-dimensional quantitative fluorescence excitation wavelength, emission wavelength, and equivalent oil content data of the reservoir rock fragment main peak as the sample point, calculate the planar offset and vertical offset between the background rock fragment main peak and the reservoir rock fragment main peak.

[0046] Step S5: Using the well with known oil test results as the modeling well, the plane offset and vertical offset data of the sample points of the modeling well are intersected. Based on the trend of the sample landing points, the valuable layer and non-value layer are divided along the landing point boundary to obtain a quantitative plane offset and vertical offset interpretation model. The reservoir value of the oil well is evaluated using this model.

[0047] Example 3: As an optimization of the above example, in step S1, the rock cuttings sample cleaning step is as follows: the rock cuttings sample is cleaned with the same oil-based fluid composition as the oil-based drilling fluid, and then the floating oil on the surface of the rock cuttings sample is rinsed with clean water.

[0048] Example 4: As an optimization of the above example, in step S1, drying is performed by low-temperature drying with an electric baking plate or by air drying.

[0049] Example 5: As an optimization of the above example, in step S1, the background rock fragments are mudstone rock fragments without oil and gas indication.

[0050] Example 6: As an optimization of the above example, in step S1, the reservoir rock fragments are one or more of sandstone, carbonate rock, and igneous rock.

[0051] Example 7: As an optimization of Example 2 above, in step S4, the planar offset is calculated according to Formula 1 below, and the vertical offset is calculated according to Formula 2 below.

[0052]

[0053] |OV|=|z i -z0| Equation 2

[0054] in,

[0055] |OH| represents the plane offset.

[0056] |OV| represents the vertical offset.

[0057] x0, y0, z0 are the coordinates of the reference point in three-dimensional space.

[0058] x i y i , z i Let i be the coordinates of the sample point in three-dimensional space, i = 1, 2, ..., n, where n is the number of reservoir rock cuttings samples.

[0059] The three-dimensional quantitative fluorescence reservoir oil and gas evaluation method for oil-based logging of this invention differs from the requirement of weighing 1g in the "Q / SY 02765-2020 Three-Dimensional Quantitative Fluorescence Logging Technical Specification". To reduce the influence of oil-based components, the sample weight of cuttings in this invention is 0.01g to 0.05g. Examples of three-dimensional fluorescence spectra of background and reservoir cuttings collected in step 2 of this invention are attached. Figure 1 and attached Figure 2 In the three-dimensional fluorescence data projection map of background rock cuttings and reservoir rock cuttings obtained in step S3 of this invention, if the projections of the sample points of background rock cuttings and reservoir rock cuttings show significant differences, the well section is judged to have good oil and gas content; if the differences between the projections are small, the well section is judged to have poor oil and gas content. (Appendix) Figure 3 This is an example of a three-dimensional fluorescence data projection image of background rock cuttings and reservoir rock cuttings obtained in step S3 of the present invention. (See attached image.) Figure 3As shown, in three-dimensional space, the black cubes representing background cuttings samples and the light gray spheres representing reservoir cuttings samples, when projected onto the excitation and emission wavelength coordinate planes, show significant differences between the two. This indicates that the well section has good oil and gas content, a judgment consistent with the well test results. The three-dimensional fluorescence data projection of background and reservoir cuttings visually demonstrates the differences in their three-dimensional quantitative fluorescence spectra, qualitatively identifying the authenticity of oil and gas in the reservoir. It also clarifies the effectiveness of three-dimensional quantitative fluorescence in oil-based logging interpretation and evaluation, laying a feasible foundation for further processing of three-dimensional quantitative fluorescence data.

[0060] Example 8: This oil-based logging three-dimensional quantitative fluorescence reservoir oil and gas evaluation method was applied to the evaluation of the 7002m to 7017m reservoir in well H6. The process is as follows:

[0061] Step S1: Collect six sandstone cuttings from the 7002m to 7017m section of well H6 as reservoir cuttings samples according to the data collection principle. Collect mudstone cuttings from before drilling and uncovering this section as background cuttings. The actual sample collected was from a depth of 6982m. Clean the background cuttings and reservoir cuttings samples with the same oil-based fluid composition as the oil-based drilling fluid. Then rinse the surface oil of the cuttings with clean water. After cleaning, dry them at low temperature using an electric baking plate for later use.

[0062] Step S2: Weigh 0.01g of rock cuttings sample and use a QFA-3D three-dimensional fluorescence spectrometer to detect and analyze the rock cuttings sample. Collect the spectrum and the excitation wavelength Em, emission wavelength Ex, and equivalent oil content data corresponding to the main peak (i.e., the highest peak) of the spectrum, as shown in Table 1.

[0063] Step S3: Input the data corresponding to the excitation wavelength, emission wavelength, and equivalent oil content of the main peaks of the background and reservoir rock cuttings into a three-dimensional coordinate space to obtain a three-dimensional fluorescence data projection map of the background and reservoir rock cuttings, as shown in the appendix. Figure 4 .like Figure 4 As shown, the spatial differences between the background rock cuttings and reservoir rock cuttings are very small, and the projections of the planar sample points almost overlap, indicating that the well section has poor oil and gas content.

[0064] Step S4: Using the three-dimensional quantitative fluorescence excitation wavelength, emission wavelength, and equivalent oil content data of the background rock fragment main peak as the reference point, and the three-dimensional quantitative fluorescence excitation wavelength, emission wavelength, and equivalent oil content data of the reservoir rock fragment main peak as the sample point, calculate the planar offset and vertical offset between the background rock fragment main peak and the reservoir rock fragment main peak according to Equation 1 and Equation 2 above, respectively. The results are shown in Table 1.

[0065] Step S5: Using wells with known oil test results as modeling wells, intersect the planar and vertical offset data of the sample points of the modeling wells. Based on the trend of the sample point landing points, divide the data into value layers and non-value layers along the landing point boundaries to obtain a quantitative interpretation model of planar and vertical offsets. (See Appendix) Figure 5 The value layer refers to the reservoir that can achieve a certain oil and gas production during the oil testing process according to the existing oilfield specifications. Specifically, it includes oil layers, oil and gas layers, oil-water co-existing layers, and gas-water co-existing layers. The non-value layer refers to the reservoir that cannot achieve a certain oil and gas production during the oil testing process according to the existing oilfield specifications. Specifically, it includes oil-bearing layers, gas-bearing layers, oil-water layers, gas-water layers, water layers, and dry layers.

[0066] The reservoir value of well H6 was evaluated using this model: Three-dimensional quantitative fluorescence data of reservoir cuttings and background cuttings from the evaluation section of well H6 were extracted and substituted into the calculation formula to obtain the three-dimensional quantitative fluorescence plane offset and vertical offset of each reservoir cuttings sample point (see Table 1). The landing points of each reservoir cuttings sample point in the quantitative plane offset and vertical offset interpretation model were then determined; all landing points were non-value layers (see Appendix). Figure 6 Oil testing confirmed that this well section produces 0.25 tons of oil and 0.053 × 10⁻⁶ tons of gas per day. 4 m 3 Daily water production 7.24m 3 The oil test results showed that the reservoir was a gas-bearing water layer, which is a non-value layer, consistent with the conclusions obtained from the oil-based logging three-dimensional quantitative fluorescence reservoir oil and gas evaluation method of this invention.

[0067] In summary, this invention improves the details of sample collection and analysis, and analyzes the changes in three parameters: three-dimensional quantitative fluorescence excitation wavelength, emission wavelength, and equivalent oil content. It establishes a three-dimensional quantitative fluorescence reservoir oil and gas evaluation method for oil-based drilling fluid contamination, reducing the impact of oil-based drilling fluid on oil and gas evaluation from the source of analysis. The method is convenient and effective, enriches the means of oil-based logging interpretation, and the quantitative evaluation is flexible and easy to promote and apply.

[0068] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

[0069] Table 1

[0070] hashtag Well depth(m) Main Peak Em Main Peak Ex Planar offset Vertical offset comparable oil content Oil test results H6 6982 280 322 4.36 H6 7003 280 322 0 1.3 3.06 Aquifer H6 7008 280 320 2 0.08 4.28 Aquifer H6 7009 280 322 0 1.786 2.574 Aquifer H6 7012 280 322 0 1.65 6.01 Aquifer H6 7013 280 322 0 0.292 4.652 Aquifer H6 7016 280 321 1 0.316 4.676 Aquifer

Claims

1. A method for oil-based mud logging three-dimensional quantitative fluorescent reservoir oil and gas evaluation, characterized in that Follow these steps: Step S1: Take rock cuttings samples from the target formation of the oil well under oil-based drilling fluid conditions, and clean and dry the rock cuttings samples; the rock cuttings samples include background rock cuttings and reservoir rock cuttings; Step S2: Weigh 0.01g to 0.05g of rock cuttings sample, and use a three-dimensional fluorescence spectrometer to detect and analyze the rock cuttings sample, and collect spectrum and detection data; the detection data includes the excitation wavelength, emission wavelength and equivalent oil content data corresponding to the main peak of the spectrum; Step S3: Input the data corresponding to the three parameters of excitation wavelength, emission wavelength and equivalent oil content of the main peak of the background rock cuttings and reservoir rock cuttings into the three-dimensional coordinate space, and project them in the coordinate plane of excitation wavelength and emission wavelength to obtain the three-dimensional fluorescence data projection map of the background rock cuttings and reservoir rock cuttings, and qualitatively determine the authenticity of the oil and gas show in the reservoir. Step S4: Using the three-dimensional quantitative fluorescence excitation wavelength, emission wavelength, and equivalent oil content data of the background rock fragment main peak as the reference point, and the three-dimensional quantitative fluorescence excitation wavelength, emission wavelength, and equivalent oil content data of the reservoir rock fragment main peak as the sample point, calculate the planar offset and vertical offset between the background rock fragment main peak and the reservoir rock fragment main peak. Step S5: Using the well with known oil test results as the modeling well, the plane offset and vertical offset data of the sample points of the modeling well are intersected. Based on the trend of the sample landing points, the valuable layer and non-value layer are divided along the landing point boundary to obtain a quantitative plane offset and vertical offset interpretation model. The reservoir value of the oil well is evaluated using this model.

2. The method for evaluating oil-based reservoir oil and gas using three-dimensional quantitative fluorescence logging according to claim 1, characterized in that... In step S1, the cleaning steps for the cuttings sample are as follows: the cuttings sample is cleaned with the same oil-based fluid composition as the oil-based drilling fluid, and then the floating oil on the surface of the cuttings sample is rinsed with clean water.

3. The three-dimensional quantitative fluorescence reservoir oil and gas evaluation method based on oil-based logging according to claim 1 or 2, characterized in that... In step S1, drying is performed by low-temperature drying using an electric baking plate or by air drying.

4. The three-dimensional quantitative fluorescence reservoir oil and gas evaluation method based on oil-based logging according to claim 1 or 2, characterized in that... In step S1, the background rock fragments are mudstone rock fragments without oil and gas indications.

5. The three-dimensional quantitative fluorescence reservoir oil and gas evaluation method based on oil-based logging according to claim 1 or 2, characterized in that... In step S1, the reservoir rock fragments are one or more of sandstone, carbonate rock, and igneous rock.

6. The method for evaluating reservoir oil and gas based on oil-based logging three-dimensional quantitative fluorescence according to claim 1, characterized in that... In step S4, the planar offset is calculated according to formula 1 below, and the vertical offset is calculated according to formula 2 below. in, |OH| represents the plane offset. |OV| represents the vertical offset. x0, y0, z0 are the coordinates of the reference point in three-dimensional space. x i , y i , z i are coordinates of sample points in three-dimensional space, i = 1, 2,... n, n is the number of reservoir cuttings samples.

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