CN1448710A - Process for measuring heavy oil relative density - Google Patents

Abstract

The method of determining the relative density of heavy oil includes constituting the correcting set of representative heavy oil specimens, smoothing and standardizing processing their 13C-nuclear magnetic resonance spectrogram, regression analysis mathematically with the basic data of corresponding heavy oil relative density to establish model, and calculating the relative density of unknown oil product from its 13C-nuclear magnetic resonance spectrogram and correcting model. The method is simple and fast, and can meet the requirement of determining the relative density of heavy oil.

Description

A kind of method of measuring the mink cell focus relative density

Technical field

The invention relates to a kind of method of measuring the mink cell focus relative density, further say so and measure the method for mink cell focus relative density about a kind of nuclear magnetic resonance method (NMR).

Technical background

The light fraction content of crude oil in China is generally lower, how to make full use of and heavy component behind the lightweight oil is extracted in processing rationally, and be one of important topic of present petroleum refining research.Structure and the character of understanding these mink cell focus components are rationally to utilize their prerequisite.

The relative density of oil product is an important properties parameter, and the national standard of petroleum products density measurement is GB2540-81, i.e. pycnometer method.In the method, amount of samples is more, and operating process is manual to be finished, and automaticity is low, though pre-service simply can not obtain structures of samples information simultaneously,

Nuclear magnetic resonance (NMR) technology is used very extensive in the analysis of oil product, compare with additive method, it is fast that NMR has analysis speed, and amount of samples reaches characteristics such as sample pretreatment is simple less, and these characteristics make it have great superiority aspect research of heavy oil product.

At Symposium on Composition of petroleum Oils, Determination andEvaluation, ASTM, S.T.P.1985, No.224 has all discussed employing in 168 and Fuel, 1960,39 (2), 87,79 ¹The achievement that the H nuclear magnetic resonance method is studied mink cell focus; " University of Petroleum's journal (natural science edition), 1993,17 (1), 99-103 ", " East China University of Science's journal; 1994,20 (4), 501-521 " and " petroleum refining; 1991, (35) 2,60-65 " have all reported with the research of magnetic nuclear resonance method to the mink cell focus structure; " University of Petroleum's journal (natural science edition), 1995,19 (2) 85-90 " and " Petroleum Review, 1987,6,41-45 " study the average molecular structure of mink cell focus and the relevance of usability.

Different group diverse locations ¹³The C atom, because its residing chemical environment difference, so have different chemical shifts.Can distinguish the kind of group and the position of group by chemical shift, peak area then reflects the relativeness of each group amount of carbon atom.Therefore, oil product C ¹³The quantitative measurement data can reflect architectural characteristic, according to ¹³The nmr spectrum of C can be determined some character with structurally associated.In several pieces of patent documentations such as USP6208137, USP5675253 and USP5519319, disclose the technology of the character that adopts online NMR system prediction superpolymer, but up to now, yet there are no employing ¹³The C-NMR method is carried out method for measuring to the relative density of mink cell focus.

Summary of the invention

It is few to the purpose of this invention is to provide a kind of amount of samples, automaticity height, the method for rapid and accurate determination mink cell focus relative density.

Method provided by the invention is: representative mink cell focus sample is formed calibration set, to they ¹³The C-nmr spectrum carries out regretional analysis with corresponding mink cell focus relative density basic data with mathematical method after adopting level and smooth and standardization, sets up calibration model; According to unknown mink cell focus sample ¹³The C-nmr spectrum, the calibration model of being set up by calibration set calculates relative density.

In the assay method provided by the present invention, obtain sample ¹³The routine operation process of C-nmr spectrum is: sample is put into the baking oven heating have good mobility until it, stirring then makes sample even, drip 3 to 5 samples in test tube with little spoon, add solvent and relaxation reagent, shaking test tube to sample dissolves fully, with transfer pipet solution is moved on in the nuclear magnetic resonance sample pipe then, add cap, carry out ¹³The mensuration of C-NMR.

Because different carbon atoms have different chemical shifts, the present invention is said ¹³It is according to Fuel that C-NMR measures, 1997,76 (1), and the chemical shift of the various group carbon atoms of 9-15 report is carried out, and table 1 is classified the chemical shift of various group carbon atoms as.

Table 1

The C atomic type	Group under δ (ppm) symbol
		Aliphatic carbon	??10.0-55.0????C aliAlkane carbon atom 10.0-18.6 CH 3Carbochain terminal methyl (except two methyl) branched chain methyl (carbocyclic ring connect on the carbochain except the α and the locational methyl of β) 18.6-23.0 CH 3αTwo methyl carbocyclic rings of the same terminal of methyl on aromatic ring or the cycloalkanes connect α and the locational methyl 23.0-32.5 of β CH on the carbochain 2Methine 34.6-42.7 CH on the methylene 32.5-34.6 CH aliphatic carbon chain on alkane methylene (except the methylene of aromatic ring or cycloalkanes α and the β position) cycloalkanes2αCarbocyclic ring connects α and the locational methylene 42.7-55.0 of β CH on the carbochain αThe methine of cycloalkanes
Aromatic ring carbon	??115.0-145.0??C aroAromatic carbon atom 115.0-129.3 CH aroProton aromatic carbon 129.3-137.1 C qpAromatic series bridge carbon atom 137.1-145.0 C qsAromatic ring four alternate c atoms

In the method provided by the invention, to mink cell focus ¹³Adopted counter-rotating gated decoupling technology (inversed gated decoupling analysis) in the C-NMR quantitative test, this technology can make the integration height of carbon spectrum be proportional to carbon number.

Said ¹³The smoothing processing of C-NMR spectrogram is a kind of disposal route of eliminating little variance signal, keeping big variance signal, wherein said big variance signal is commonly referred to be a kind of useful analytic signal, little variance signal then often is the contribution of stochastic error or noise etc., referring to " " Essential Chemistry metrology "; Science Press, 40-48 page or leaf ".In the method provided by the invention, the window number strong point of said employing smoothing processing method is n=2m+1, the preferred 2-8 of m wherein, and more preferably m is 3-6.

Said ¹³The standardization of C-NMR spectrogram is a j integrated value to each sample, with the matrix X of n sample composition, $X=\left[\begin{array}{cccc}{x}_{11}& x_{12}& \·\·\·& x_{1j}\\ x_{21}& x_{22}& \·\·\·& x_{2j}\\ \·& \·& \·& \·\\ \·& \·& \·& \·\\ \·& \·& \·& \·\\ x_{n1}& x_{n2}& \·\·\·& x_{\mathrm{nj}}\end{array}\right],{x_{\mathrm{ij}}}^{*}=\frac{x_{\mathrm{ij}}-\stackrel{\‾}{x_j}}{S_J},S_j=\sqrt{\frac{1}{n}\underset{j=1}{\overset{n}{\mathrm{\Σ}}}{(x_{\mathrm{ij}}-\stackrel{\‾}{x_j})}^2}$ Wherein, Be the integrated value that obtains after the standardization; x _IjIt is the integrated value of j integrating range of i sample; Mean value for j integrating range integrated value of all samples; S _jIt is the standard deviation of j integrating range integrated value.

In the method provided by the invention, the relative density basic data of forming the mink cell focus sample of calibration set obtains with standard method, as the GB2540-81 standard method.

In the method provided by the invention, the said basic data of concentrated mink cell focus relative density of will proofreading and correct is with corresponding ¹³The mathematical method that the C-NMR data are carried out regretional analysis is meant multivariate calibration methods, can be classical least square method (CLS), contrary least square method (ILS), multiple linear regression (MLR), principal component regression (PCR), partial least square method (PLS), sane partial least square method (RPLS) or artificial neural network (ANN), wherein preferred partial least square method (PLS).

Adopt multivariate calibration methods that basic data and corresponding nuclear magnetic resoance spectrum are carried out regretional analysis, can obtain the calibration model of respective components.

When adopting partial least square method (PLS), integrated value matrix X (as implied above) is the independent variable matrix, the character matrix $Y=\left[\begin{array}{c}{y}_1\\ y_2\\ \·\\ \·\\ \·\\ y_n\end{array}\right]$ Be dependent variable matrix, wherein y _iBe the character (relative density) of i sample.

The mathematical model of calibration model is Y=XK+E, and wherein K is a matrix of coefficients, and E is the character residual matrix.

The general algorithm that its calibration model is set up is:

1. pretreated character matrix Y and integrated value matrix X are carried out the major component decomposition, $Y={\mathrm{TV}}^t+E_Y=\underset{k=1}{\overset{p}{\mathrm{\Σ}}}{t}_k{v}_k^t+E_Y----\left(1\right)$ $X={\mathrm{RQ}}^t+E_X=\underset{k=1}{\overset{p}{\mathrm{\Σ}}}{r}_k{q}_k+E_X----\left(2\right)$

r _k=b _kt _k(3) wherein: t _k(m * 1) is the factor score of character matrix,

v _k(1 * n) is the factor loading of character matrix,

r _k(m * 1) is the factor score of integrated value matrix,

q _k(1 * 1) is the factor loading of integrated value matrix,

b _k(1 * 1) is r _kAnd t _kRegression coefficient,

P is the main cause subnumber.

2. find the solution eigenvector and main cause subnumber p

Be the general process that eigenvector and main cause subnumber p are found the solution below:

When ignoring residual error battle array E,, have during p=1 according to formula (1) and (2):

Y=tv ^tPremultiplication t ^t: v ^t=t ^tY/t ^tt

The right side takes advantage of v to get: t=Yv/v ^tv

X=rq premultiplication r ^t: q=r ^tX/r ^tR, both sides are with getting divided by q: r=X/q

[1] ask the weight vectors w of character matrix,

The a certain row of getting integrated value battle array X are made the initial iterative value of r, replace t with r, calculate w

Equation: Y=rw ^tSeparate: t=Yw/w ^tw

[2] normalization w:

[3] ask the factor score t of character matrix, calculate t by w after the normalization,

Equation: Y=tw ^tSeparate: t=Yw/w ^tw

[4] the quadrature weight u value of value matrix replaces r to calculate u with t,

Equation: X=tu separates: u=t ^tX/t ^tt

[5] the quadrature factor score r of value matrix calculates r by u,

Equation: X=ru separates: r=X/u

Replace t to return for [1] step with this r again and calculate w ^t, by w ^tCalculate t _Newly, so iterate, restrain (‖ t as t _Newly-t _Old‖≤10 ^-6‖ t _Newly‖), continue step computing down, otherwise return step [1].

[6] ask the load vector v of character matrix by the t after the convergence,

Equation: Y=tv ^tSeparate: v ^t=t ^tY/t ^tt

[7] by the quadrature load q value of value matrix of r,

Equation: X=rq separates: q=r ^tX/r ^tr

Obtain r thus corresponding to first main gene ₁, q ₁, t ₁,

Substitution formula (3) is obtained b ₁: $b_1=r_1{t}_1/t_1^t{t}_1$

[8] calculate residual error E by formula (1) and (2),

E _X，1＝X-r ₁q ₁＝X-b ₁t ₁q ₁??????????????(4)

E _Y，1＝Y-t ₁v?????????????????????????(5)

[9] with E _{X, 1}Replace X, E _{Y, 1}Replace Y, return the r that step [1] is calculated next component ₂, q ₂, t ₂,

b ₂

[10] calculate E by formula (4) and (5) _{X, 2}, E _{Y, 2}, by that analogy, obtain all main genes of X, Y.

Determine main cause subnumber p with the cross-verification method.

Through above process, calibration model is set up and is finished.

By unknown sample ¹³C-NMR composes x _{(the unknown)}And calibration model is set up the q that stores in the process _kAnd formula (2) is calculated r _{K (the unknown)}, By the r that obtains _{K (the unknown)}With the b that stores in the trimming process _kAnd formula (3) r _k=b _kt _kCalculate t _{K (the unknown)}, t _{K (the unknown)}=r _{K (the unknown)}/ b _k, by the t that obtains _{K (the unknown)}And the v of storage _kAnd formula (1) $Y={\mathrm{TV}}^t+E_Y=\underset{k=1}{\overset{p}{\mathrm{\Σ}}}{t}_k{v}_k^t+E_Y$ Calculate y _{(the unknown)}

Method provided by the invention is the quadratic method that is based upon on the standard relative density assay method basis, is suitable for setting up the scope that the calibration model sample is contained, and therefore requires the sample in the said calibration set representative, and coverage is wide, is evenly distributed.

The method of mensuration mink cell focus relative density provided by the invention can obtain the relative density data when obtaining the structural information of oil product, have following characteristics:

1) result that measures of method provided by the present invention and the standard deviation of measured value are no more than 0.0008 gram per centimeter ³, satisfy of the mensuration requirement of heavy oil phase to density.

2) adopt the method for paired t check that otherness is tested, when the given level of signifiance 0.05, promptly during degree of confidence 0.95, the t value that fruit is assembled in checking is 0.31, less than t (0.05,5)=2.45, illustrate that the result that method provided by the invention and standard method draw is consistent.

Embodiment

Following example will the present invention is further illustrated, but protection scope of the present invention is not subjected to the restriction of these examples.

Example

1,19 mink cell focus samples is formed calibration set, adopt their the relative density basic data of method mensuration of GB2540-81 record, see Table 2 measured values row.

2, mink cell focus calibration set The pretreatment and ¹³C-NMR measures.

(1) time delay: 3 seconds

(2) flip angle: 2.5 microseconds

(3) accumulative frequency :～5000

(4) sampling time: 0.2 second

Sample is put into the baking oven heating make it have good mobility, stirring makes sample even then, drips 3 to 5 samples in test tube with little spoon, adds 0.5 milliliter of CDCl ₃(deuterochloroform) adds relaxation reagent (Chromium AcetylaceTomateChromium (III) trislacetylacetonato[Cr (acac) again as solvent (tetramethylsilane that contains 5 ‰ volume contents) ₃], U.S. varian company product), shake test tube to sample and dissolve fully, with transfer pipet solution is moved on in the nuclear magnetic resonance sample pipe of Φ 5mm then, add cap, carry out ¹³The mensuration of C-NMR, nuclear magnetic resonance analyser are that Switzerland produces Bruker AM-300HZ type instrument.

3, to the sample gained in the calibration set ¹³The C-NMR spectrogram adopts 9 level and smooth and standardizations, adopts partial least square method to carry out regretional analysis with the relative density basic data again, determines that by cross verification the main cause subnumber is 3, obtains the calibration model of relative density.

Measurement result after sample is proofreaied and correct with calibration model in the calibration set sees Table 2 measured values row.In table 2, $\mathrm{SEC}=\sqrt{\frac{\mathrm{\Σ}{(y_b-y)}^2}{n-1}},$ Be the calibration set standard deviation, in the formula: y _bBe the result who measures with standard method; Y is for passing through ¹³The result that C-NMR measures; N is the calibration set sample number.Table 2

Sequence number	The calibration set sample	Measured value g/cm 3	Measured value g/cm 3	Prediction deviation g/cm 3
					????1	The Sudan Boban crude oil＞480 ℃	????0.9798	????0.9800	????0.0002
????2	Tell red＞430 ℃	????0.9804	????0.9801	????-0.0003
					????3	T032	????1.0121	????1.0113	????-0.0008
????4	Subtract slag in the sand of Zhenghai	????1.0321	????1.0315	????-0.0006
					????5	Zhenghai 90#	????1.0279	????1.0279	????0.0000
????6	608G# mixes (1)	????0.9974	????0.9970	????-0.0004
					????7	608G# mixes (2)	????0.9976	????0.9985	????0.0009
????8	The Sudan Boban crude oil＞480 ℃ (baking back)	????0.9849	????0.9843	????-0.0006
					????9	Yemen 70#	????1.0166	????1.0168	????0.0002
????10	90# in the sand of Maoming	????1.0288	????1.0288	????0.0000
					????11	99 oxygen-8 Oman 90#	????1.0124	????1.0124	????0.0000
????12	East River 70#	????1.0256	????0.0260	????0.0004
					????13	In the sand＞525 ℃	????1.0349	????1.0350	????0.0001
????14	North slope＞480 ℃	????1.0079	????1.0078	????-0.0001
					????15	Tell red＞435 ℃ (the baking back of imposing uniformity without examining individual cases)	????0.9783	????0.9784	????0.0001
????16	Oman＞542 ℃	????1.0103	????1.0098	????-0.0005
					????17	Oman S99-24 deasphalting oxygen-1	????1.0147	????1.0157	????0.0010
????18	The wide petrochemical industry 90# of 99 oxygen-11	????1.0166	????1.0165	????-0.0001
					????19	Tell red＞435 ℃ (single solution for diverse problems)	????0.9843	????0.9848	????0.0005
??????????????????????????SEC				????0.0005

4, to 6 mink cell focus sample determinations to be measured ¹³C-NMR calls calibration model and obtains the relative density value, and measurement result sees Table 3 measured values row.

In table 3, $\mathrm{SEP}=\sqrt{\frac{\mathrm{\Σ}{(y_b-y)}^2}{m-1}},$ Be the standard deviation of mink cell focus sample to be measured, m is the sample number of checking collection; D is the mean value of difference between standard method and the assay method measured value provided by the invention; S _dIt is the standard deviation of difference between the two method measured values.

Antithesis t method of inspection can be used for determining the difference of method provided by the present invention and conventional method measured result, and when given level of significance is 0.05, promptly degree of confidence is 0.95 o'clock, | the t| value is 0.31, the t that is put down in writing less than the t distribution table _(0.05,5)Value 2.45 illustrates assay method provided by the invention and standard method measured result there was no significant difference, is consistent.

Show that from the standard deviation and the antithesis t assay of measured result assay method provided by the invention can obtain the relative density value of mink cell focus accurately.

Table 3

Sequence number	Unknown sample	Measured value g/cm 3	Measured value g/cm 3	Prediction deviation g/cm 3
					????1	The Sudan Boban crude oil＞500 ℃ (baking back)	????0.9827	????0.9824	????-0.0003
????2	99 oxygen-5	????1.0104	????1.0118	????0.0014
					????3	Reddle crude oil＞430 ℃ (the baking back of imposing uniformity without examining individual cases)	????0.9825	????0.9827	????0.0002
????4	2# jar north slope pitch	????1.0288	????1.0284	????-0.0004
					????5	In the sand＞520 ℃	????1.0291	????1.0284	????-0.0007
????6	North slope 50#	????1.0169	????1.0174	????0.0005
					???????????????????????????SEP????????????????????????????????0.0008 ?????????????????????????? d?????????????????????????????????0.0001 ???????????????????????????S d????????????????????????????????0.0008 ???????????????????????????|t|????????????????????????????????0.31 ???????????????????????????t(0.05，5)?????????????????????????2.45

Claims (6)

1, a kind of method of measuring the mink cell focus relative density is characterized in that representative mink cell focus sample is formed calibration set, to they ¹³The C-nmr spectrum carries out regretional analysis with the basic data of corresponding mink cell focus sample relative density with mathematical method after adopting level and smooth and standardized processing, sets up calibration model; According to unknown mink cell focus sample ¹³The C-nmr spectrum, the calibration model of being set up by calibration set calculates relative density.

2, according to the said method of claim 1, it is characterized in that the window number strong point n=2m+1 of the data point of said smoothing processing, wherein m is 2-8.

3,, it is characterized in that said m is 3-6 according to the said method of claim 2.

4,, it is characterized in that said with the calibration set sample according to the said method of claim 1 ¹³The mathematical method that the relative density basic data that C-nuclear magnetic resonance data phase and phase is answered is carried out regretional analysis is meant multivariate calibration methods.

5,, it is characterized in that said multivariate calibration methods is selected from a kind of in classical least square method (CLS), contrary least square method (ILS), multiple linear regression (MLR), principal component regression (PCR), partial least square method (PLS), sane partial least square method (RPLS) or the artificial neural network (ANN) according to the said method of claim 1.

6,, it is characterized in that wherein said multivariate calibration methods is partial least square method (PLS) according to the said method of claim 1.