Spectroscopic detection method of fracturing fluid drilling fluid

Abstract

The present application provides a kind of fracturing fluid drilling fluid spectral detection method, comprising the following steps: step 1, different concentration fracturing fluid and drilling fluid are matched out;Step 2, the absorption spectrum of different concentration fracturing fluid and drilling fluid is obtained;Step 3, based on partial least squares regression method, the absorption spectrum and concentration of different concentration fracturing fluid and drilling fluid are used to establish the inversion model of absorption spectrum and concentration to principal component;Step 4, the content of fracturing fluid and drilling fluid in the liquid to be measured is detected by inversion model.The present application uses absorption spectrum to quantitatively detect the content of fracturing fluid and drilling fluid in groundwater, which is beneficial to provide effective data basis for groundwater source fracturing fluid and drilling fluid pollution degree evaluation and timely management, can overcome the problem of difficult groundwater quality detection after shale gas exploitation, has the characteristics of short time consumption, low cost, small workload and sustainable detection.

Description

Technical Field

[0001] This invention relates to the field of hyperspectral quantitative detection technology, and more specifically, to a method for the spectroscopic detection of fracturing fluid and drilling fluid. Background Technology

[0002] With increasing demand for natural gas, shale gas, as a new type of unconventional natural gas, is attracting more and more attention. Drilling fluid and fracturing fluid are two important substances in shale gas extraction. During the extraction process, they are in prolonged contact with the wellbore, inevitably leading to leakage, primarily through seepage into the formation, which can pollute groundwater. Therefore, monitoring fracturing fluid and drilling fluid in groundwater after shale gas extraction provides a valuable data foundation for assessing the degree of pollution from these substances and for timely remediation.

[0003] Fracturing fluids and drilling fluids are diverse, involving hundreds of types of organic matter. While traditional monitoring methods such as chemical analysis and chromatography offer wide applicability and accuracy, they suffer from drawbacks such as long processing times, high costs, heavy workloads, and lack of continuity. In recent years, ultraviolet-visible (UV-Vis) spectroscopy has gained increasing attention due to its significant advantages over traditional chemical analysis methods. UV-Vis spectroscopy requires no chemical reagents or sample treatment, minimizing its impact on water quality. Furthermore, it offers rapid monitoring and can simultaneously detect multiple parameters. However, due to limitations in its detection mechanism, UV-Vis spectroscopy is susceptible to environmental factors such as temperature, turbidity, and light scattering, thus its primary application is in the detection of organic pollution in water bodies. Since fracturing fluids and drilling fluids contain large amounts of organic matter, and if groundwater pollution is unavoidable, UV-Vis spectroscopy can provide effective detection. Summary of the Invention

[0004] The present invention aims to provide a spectral detection method for fracturing fluid and drilling fluid to solve the problems of traditional detection methods for fracturing fluid and drilling fluid, such as long time consumption, high cost, large workload and lack of continuity.

[0005] The present invention provides a spectral detection method for fracturing fluid drilling fluid, comprising the following steps:

[0006] Step 1: Prepare fracturing fluid and drilling fluid of different concentrations;

[0007] Step 2: Obtain the absorption spectra of fracturing fluid and drilling fluid at different concentrations;

[0008] Step 3: Based on partial least squares regression, an inversion model of absorption spectrum and concentration on principal components is established using the absorption spectra and concentrations of fracturing fluid and drilling fluid at different concentrations.

[0009] Step 4: The content of fracturing fluid and drilling fluid in the test fluid is detected by inversion model.

[0010] Furthermore, the method for preparing fracturing fluid and drilling fluid of different concentrations described in step 1 includes:

[0011] Fracturing fluid and drilling fluid are diluted to different degrees using pure water as the base fluid;

[0012] The minimum and maximum detectable concentrations of fracturing fluid and drilling fluid are determined by absorption spectroscopy, thereby determining the effective concentration range of fracturing fluid and drilling fluid.

[0013] Diluted fracturing fluid and drilling fluid are mixed at different concentration ratios within the effective concentration range to prepare fracturing fluid and drilling fluid of different concentrations.

[0014] Furthermore, the fracturing fluids and drilling fluids of different concentrations include:

[0015] Single-parameter solutions of fracturing fluid or drilling fluid;

[0016] And / or a mixture of fracturing fluid and drilling fluid.

[0017] Furthermore, the method for obtaining the absorption spectra of fracturing fluid and drilling fluid at different concentrations in step 2 is as follows:

[0018] Absorption spectra of fracturing fluid and drilling fluid of different concentrations were collected using a 10nm optical path length, thereby obtaining the absorption spectra of fracturing fluid and drilling fluid of different concentrations.

[0019] Furthermore, after obtaining the absorption spectra of fracturing fluid and drilling fluid of different concentrations in step 2, the process also includes data preprocessing of the obtained absorption spectra of fracturing fluid and drilling fluid of different concentrations. Step 3 utilizes the absorption spectra of fracturing fluid and drilling fluid of different concentrations after data preprocessing.

[0020] Furthermore, the data preprocessing method is as follows:

[0021] The absorption spectrum is smoothed and denoised using a polynomial moving average filtering method.

[0022] Furthermore, in step 3, based on partial least squares regression, the method for establishing an inversion model of absorption spectra and concentrations on principal components using the absorption spectra and concentrations of fracturing fluids and drilling fluids of different concentrations includes:

[0023] The absorption spectra and concentrations of fracturing fluid and drilling fluid of different concentrations were standardized to obtain the standardized absorption spectrum matrix and concentration matrix.

[0024] Calculate the correlation coefficient matrix of the standardized absorption spectrum matrix and concentration matrix, and then calculate the k principal components of the absorption spectrum and concentration matrix.

[0025] When the ratio of the analytical absorption spectral matrices of the k principal components is greater than the ratio of the target accuracy, regression equations for the standardized absorption spectral matrix and concentration matrix on the principal components are established, thereby obtaining the inversion model of absorption spectrum and concentration on the principal components.

[0026] Furthermore, the absorption spectra of fracturing fluid and drilling fluid at different concentrations obtained in step 2 are divided into two parts, with proportions a and b. The first part, consisting of the absorption spectra of fracturing fluid and drilling fluid at different concentrations and their corresponding concentrations, is used in step 3 to establish the inversion model of absorption spectrum and concentration on the principal component. The second part, consisting of the absorption spectra of fracturing fluid and drilling fluid at different concentrations and their corresponding concentrations, is used to evaluate the established inversion model of absorption spectrum and concentration on the principal component. Here, a + b = 1. Generally, a = 80%, b = 20%.

[0027] Furthermore, the absorption spectrum refers to the ultraviolet-visible absorption spectrum, that is, the absorption spectrum in the 210-600 nm wavelength range.

[0028] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0029] This invention utilizes absorption spectroscopy to quantitatively detect the content of fracturing fluid and drilling fluid in groundwater, which is beneficial for providing an effective data basis for assessing the degree of pollution of fracturing fluid and drilling fluid in groundwater sources and for timely treatment. It can overcome the problem of difficulty in groundwater quality testing after shale gas extraction and has the characteristics of short time consumption, low cost, small workload and sustainable testing. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a flowchart of the spectral detection method for fracturing fluid and drilling fluid in an embodiment of the present invention.

[0032] Figure 2a This is the UV-Vis absorption spectrum of the fracturing fluid after data preprocessing in this invention.

[0033] Figure 2b This is the ultraviolet-visible absorption spectrum of the drilling fluid after data preprocessing in this invention.

[0034] Figure 3 This is a graph showing the verification results of the absorption spectrum and concentration inversion model of the principal component in this embodiment of the invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0037] Example

[0038] This embodiment proposes a spectroscopic detection method for fracturing and drilling fluids to detect the degree of groundwater pollution caused by the leakage of fracturing and drilling fluids during current shale gas extraction processes. Figure 1 As shown, the spectral detection method for fracturing fluid drilling fluid includes the following steps:

[0039] Step 1: Prepare fracturing fluids and drilling fluids of different concentrations; specifically:

[0040] Fracturing fluid and drilling fluid are diluted to different degrees using pure water as the base fluid;

[0041] The minimum and maximum detectable concentrations of fracturing fluid and drilling fluid are determined by absorption spectroscopy, thereby defining the effective concentration range of fracturing fluid and drilling fluid; where the minimum and maximum detectable concentrations refer to the concentrations that can be distinguished based on the stability of the micro spectrometer and the spectral distinguishability.

[0042] Diluted fracturing fluid and drilling fluid are mixed at different concentration ratios within the effective concentration range to prepare fracturing fluids and drilling fluids of different concentrations. Optionally, the fracturing fluids and drilling fluids of different concentrations include:

[0043] (1) Single-parameter solutions of fracturing fluid or drilling fluid; In this embodiment, 30 sample solutions with fracturing fluid concentration ratios ranging from 0.01 to 0.6 and 30 sample solutions with drilling fluid concentration ratios ranging from 0.0002 to 0.0034 were taken.

[0044] (2) A mixed solution of fracturing fluid and drilling fluid; In this embodiment, about 10 sample solutions of the mixed solution of fracturing fluid and drilling fluid were taken.

[0045] Step 2: Obtain the absorption spectra of fracturing fluid and drilling fluid at different concentrations; specifically:

[0046] Absorption spectra of fracturing fluid and drilling fluid of different concentrations were collected using a 10nm optical path length, thereby obtaining the absorption spectra of fracturing fluid and drilling fluid of different concentrations; wherein, the absorption spectrum refers to the ultraviolet-visible absorption spectrum, that is, the absorption spectrum in the 210-600nm band.

[0047] The absorption spectra of fracturing fluid and drilling fluid at different concentrations were preprocessed, such as... Figure 2a , 2b As shown; optionally, the data preprocessing method is to smooth and denoise the absorption spectrum using the Savitzky-Golay polynomial moving average filtering method. The basic idea of ​​the polynomial moving average filtering method is to fit a certain amount of data using a polynomial fitting method, which can retain useful information of the absorption spectrum and eliminate random noise. First, the size of the spectral smoothing window is determined to be n = 2m + 1, where m is an arbitrary constant, the purpose of which is to ensure that n is the base; each absorption spectrum is x, and a k-1 degree polynomial is mainly selected to fit the absorption spectrum within the window range, resulting in the following fitting equation:

[0048] y = a0 + a1x + a2x 2 +…+a k-1 x k-1 (1)

[0049] Where x represents n consecutive absorption spectra in each sample, a0, a1, a2, ..., a k-1 For multiple coefficients, y is the predicted value.

[0050] The absorption spectrum of each band can form an equation, resulting in a system of n linear equations with k variables. Generally, n > k is chosen. The fitting parameters A are determined by fitting using the least squares method, thus obtaining:

[0051]

[0052] In the formula, a is the coefficient and e is the residual;

[0053] The matrix is ​​represented as:

[0054] Y (2m+1)*1 =X (2m+1)*k ·A k*1 +E (2m+1)*1 (2)

[0055] In the formula, the subscripts of each parameter represent their respective dimensions, such as A k*1 The parameter represents k rows and 1 column; X is the absorption spectrum matrix; E is the residual matrix.

[0056] Least square solution of fitting parameter A for:

[0057]

[0058] Then the model predicted value or filtered value for:

[0059]

[0060] B = X·(X) T ·X) -1 ·X T (5)

[0061] Step 3: Based on partial least squares regression, using the absorption spectra and concentrations of fracturing fluid and drilling fluid at different concentrations, establish an inversion model of absorption spectra and concentrations on the principal components; specifically:

[0062] The absorption spectra and concentrations of fracturing fluid and drilling fluid of different concentrations were standardized to obtain the standardized absorption spectrum matrix X and concentration matrix Y.

[0063]

[0064]

[0065]

[0066] In the formula, X ij (n×m) represents the j-th band element of the i-th sample in the standardized absorption spectral matrix X; X ij This represents the element in the j-th band of the i-th sample in the absorption spectral matrix X; This represents the mean value of all concentrations in the absorption spectral matrix X in the j-th band; This represents the standard deviation of all concentrations in the absorption spectral matrix X in the j-th band;

[0067] Calculate the correlation coefficient matrix between the standardized absorption spectrum matrix and the concentration matrix, find the eigenvector ρ corresponding to the largest eigenvalue, and then calculate the k principal components of the absorption spectrum matrix X and the concentration matrix Y, which are U... k and V k and its score vector and

[0068] M = X T YY T X

[0069]

[0070]

[0071]

[0072] In the formula, U k V is the largest eigenvalue of the k-th principal component of the absorption spectral matrix X. k ρ is the largest eigenvalue of the k-th principal component of the concentration matrix Y. k U is the kth principal component k The corresponding eigenvector; γ k V is the kth principal component k The corresponding feature vector;

[0073] When the ratio of the analytical absorption spectral matrices of the k principal components is greater than the target accuracy (e.g., 95%), a regression equation for the principal components is established using the standardized absorption spectral matrix and concentration matrix, thus obtaining the inversion model of absorption spectrum and concentration for the principal components.

[0074]

[0075]

[0076] In the formula, I is the identity matrix; i is the position of the principal component; ρ j X is the absorption spectrum matrix corresponding to the j-th iteration. j-1 The eigenvectors of , satisfying τ i =X j-1 ρ j ;τ i Let σ be the score matrix for the i-th iteration; j Let X be the regression coefficient matrix of the principal component and the absorption spectrum matrix X in the j-th iteration;

[0077] Subsequently, the weight coefficients and intercept of the regression equation for the original data are obtained further using the following formula:

[0078]

[0079]

[0080] In the formula, F j W represents the intercepts of fracturing fluid and drilling fluid. ij represents the weighting coefficients for fracturing fluid and drilling fluid at the i-th wavelength; The mean and root mean square error of the fracturing fluid and drilling fluid concentrations; This represents the mean and root mean square error of column i of the absorption spectral matrix.

[0081] The constructed water quality parameter inversion model is as follows:

[0082] Y predict (n,p)=F(p)+X(n,m)*W(m,P) (10)

[0083] In the formula, Y predict (n,p) represents the predicted concentration matrix of the drilling fluid or fracturing fluid in the water sample to be tested, and X(n,m) is the ultraviolet-visible absorption spectrum matrix of the water sample to be tested. p represents the fracturing fluid or drilling fluid.

[0084] In this embodiment, the absorption spectra of fracturing fluid and drilling fluid of different concentrations obtained in step 2 are divided into two parts, a and b, respectively. The first part, consisting of the absorption spectra of fracturing fluid and drilling fluid of different concentrations and their corresponding concentrations, is used in step 3 to establish the inversion model of absorption spectrum and concentration on principal components. The second part, consisting of the absorption spectra of fracturing fluid and drilling fluid of different concentrations and their corresponding concentrations, is used to evaluate the established inversion model of absorption spectrum and concentration on principal components. Here, a + b = 1. Generally, a = 80% and b = 20%. Therefore, for the 70 sample solutions with absorption spectra of fracturing fluid and drilling fluid of different concentrations obtained in step 2, the absorption spectra of 56 sample solutions and their corresponding concentrations are used in step 3 to obtain the inversion model of absorption spectrum and concentration on principal components.

[0085] Step 4: The content of fracturing fluid and drilling fluid in the test fluid is detected using an inversion model. For example, the remaining 14 sample groups are used to evaluate the absorption spectrum and concentration inversion model of the principal components. Figure 3 As shown, the absorption spectrum and concentration inversion model for the principal components has good inversion accuracy.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for spectroscopic detection of fracturing fluid drilling fluid, characterized in that, Includes the following steps: Step 1: Prepare fracturing fluid and drilling fluid of different concentrations; Step 2: Obtain the absorption spectra of fracturing fluid and drilling fluid at different concentrations; the absorption spectrum refers to the ultraviolet-visible absorption spectrum, that is, the absorption spectrum in the 210-600nm wavelength range; Step 3: Based on partial least squares regression, an inversion model of absorption spectrum and concentration on principal components is established using the absorption spectra and concentrations of fracturing fluid and drilling fluid at different concentrations. Step 4: Detect the content of fracturing fluid and drilling fluid in the test fluid using an inversion model; Step 3, based on partial least squares regression, utilizes the absorption spectra and concentrations of fracturing fluids and drilling fluids of different concentrations to establish an inversion model of the principal components based on absorption spectra and concentrations. The method includes: The absorption spectra of fracturing fluid and drilling fluid at different concentrations were standardized to obtain the standardized absorption spectral matrix X. and concentration matrix Y ; In the formula, X represents the normalized absorption spectrum matrix. The i-th sample and the j-th band element; This represents the element in the j-th band of the i-th sample in the absorption spectral matrix X; This represents the mean value of all concentrations in the absorption spectral matrix X in the j-th band; This represents the standard deviation of all concentrations in the absorption spectral matrix X in the j-th band; Calculate the correlation coefficient matrix between the standardized absorption spectrum matrix and the concentration matrix, and find the eigenvector corresponding to the largest eigenvalue. Then, the standardized absorption spectrum matrix X is calculated. and concentration matrix Y k pairs of principal components, respectively U k and V k and its score vector and ; In the formula, The normalized absorption spectrum matrix X The largest eigenvalue of the k-th principal component The standardized concentration matrix Y The largest eigenvalue of the k-th principal component For the k-th principal component The corresponding feature vector; For the k-th principal component The corresponding feature vector; When the ratio of the analytical absorption spectral matrices of the k principal components is greater than the ratio of the target accuracy, regression equations are established for the standardized absorption spectral matrix and concentration matrix on the principal components, thus obtaining the inversion model of absorption spectrum and concentration on the principal components: In the formula, I is the identity matrix; i is the position of the principal component; The normalized absorption spectrum matrix corresponding to the j-th iteration The eigenvectors of satisfy . ; Let be the score matrix for the i-th iteration; Let X be the principal component and the normalized absorption spectrum matrix of the j-th iteration. The regression coefficient matrix; Subsequently, the weight coefficients and intercept of the regression equation for the original data are obtained further using the following formula: In the formula, The intercept of the regression equation; These are the weighting coefficients of the regression equation at the i-th wavelength; , This represents the mean and root mean square error of the j-th column of the concentration matrix; , The mean and root mean square error of column i of the absorption spectral matrix represent the value of band i. The constructed water quality parameter inversion model is as follows: In the formula, This represents the predicted concentration matrix of drilling fluid or fracturing fluid in the water sample to be tested. denoted as the UV-Vis absorption spectrum matrix of the water sample to be tested, where p represents the fracturing fluid or drilling fluid.

2. The spectral detection method for fracturing fluid and drilling fluid according to claim 1, characterized in that, The method for preparing fracturing fluids and drilling fluids of different concentrations as described in step 1 includes: Fracturing fluid and drilling fluid are diluted to different degrees using pure water as the base fluid; The minimum and maximum detectable concentrations of fracturing fluid and drilling fluid are determined by absorption spectroscopy, thereby determining the effective concentration range of fracturing fluid and drilling fluid. Diluted fracturing fluid and drilling fluid are mixed at different concentration ratios within the effective concentration range to prepare fracturing fluid and drilling fluid of different concentrations.

3. The spectral detection method for fracturing fluid and drilling fluid according to claim 1 or 2, characterized in that, The fracturing fluids and drilling fluids of different concentrations include: Single-parameter solutions of fracturing fluid or drilling fluid; And / or a mixture of fracturing fluid and drilling fluid.

4. The spectral detection method for fracturing fluid and drilling fluid according to claim 1, characterized in that, The method for obtaining the absorption spectra of fracturing fluid and drilling fluid at different concentrations in step 2 is as follows: Absorption spectra of fracturing fluid and drilling fluid of different concentrations were collected using a 10nm optical path length, thereby obtaining the absorption spectra of fracturing fluid and drilling fluid of different concentrations.

5. The spectral detection method for fracturing fluid and drilling fluid according to claim 1 or 4, characterized in that, After obtaining the absorption spectra of fracturing fluid and drilling fluid of different concentrations in step 2, the process also includes data preprocessing of the obtained absorption spectra of fracturing fluid and drilling fluid of different concentrations. Step 3 utilizes the absorption spectra of fracturing fluid and drilling fluid of different concentrations after data preprocessing.

6. The spectral detection method for fracturing fluid and drilling fluid according to claim 5, characterized in that, The data preprocessing method is as follows: The absorption spectrum is smoothed and denoised using a polynomial moving average filtering method.

7. The spectral detection method for fracturing fluid and drilling fluid according to claim 1, characterized in that, The absorption spectra of fracturing fluid and drilling fluid of different concentrations obtained in step 2 are divided into two parts with proportions a and b. The absorption spectra of fracturing fluid and drilling fluid of different concentrations in the first part and their corresponding concentrations are used to establish the inversion model of absorption spectrum and concentration on principal components in step 3. The absorption spectra of fracturing fluid and drilling fluid of different concentrations in the second part and their corresponding concentrations are used to evaluate the established inversion model of absorption spectrum and concentration on principal components. Wherein, a+b=1.

8. The spectral detection method for fracturing fluid and drilling fluid according to claim 7, characterized in that, a=80%, b=20%.

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