CN106154343B - Method for calculating oil saturation of tight oil reservoir - Google Patents
Method for calculating oil saturation of tight oil reservoir Download PDFInfo
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Abstract
The invention provides a method for calculating oil saturation of a compact oil reservoir. The method comprises the following steps: collecting data by using a nuclear magnetic resonance logging instrument, and obtaining transverse relaxation time T through data processing2A spectrum; determining a transverse relaxation time threshold for the tight oil reservoir that is hydrophilic or neutrally wetted, corresponding to a lower limit of the pore throat radius; continuously calculating the content of the compact oil reservoir according to the transverse relaxation time T2 spectrum and the transverse relaxation time threshold valueOil saturation. The method is based on nuclear magnetic resonance logging data, and forms a brand new transverse relaxation time T applying nuclear magnetic resonance by determining the nuclear magnetic resonance transverse relaxation minimum time threshold corresponding to the lower limit of the oil-containing pore throat radius of a compact oil reservoir under the condition of hydrophilic or neutral wetting2A method for directly calculating the oil saturation of a compact oil reservoir by a spectrum.
Description
Technical field
The present invention relates to petroleum exploration domains, in particular to a kind of oil saturation calculating fine and close oily reservoir
Method.
Background technology
Oil saturation is the important parameter of reservoir oiliness characterization.For conventional reservoir, stored up with the method for well logging
The method of layer oil saturation usually has electrical log, nuclear magnetic resonance log and C/O to compare spectrometry logging.For fine and close oily reservoir,
The application of above-mentioned logging method is restricted.
Wherein, electrical log calculates saturation degree needs and porosity logging use in conjunction, and oil-containing saturation is calculated using following formula
Degree：In formula：Φ is the porosity value that porosity logging obtains, decimal；A, b, m, n are that rock electricity is real
Test parameter, dimensionless；RT is the formation resistivity that electrical log obtains, Ω .m；Rw is formation water resistivity, Ω .m.However, right
For fine and close oil, water is not produced on stratum usually, is unable to get formation water resistivity data, above-mentioned to effectively can not directly apply
Formula calculates oil saturation.C/O is to have higher porosity than the condition that spectrometry logging is applied, and it is relatively high could to obtain noise
Well-log information, fine and close oil reservoir porosity is usually relatively low, and this method is also not suitable for.
Calculating oil saturation using NMR logging data, usually there are two types of methods：One is by nuclear magnetic resonance log
Relaxation wave spectrum be converted to pseudo- capillary pressure curve, in the case of known oil-water interfaces and grease density contrast, calculate every bit
Oil saturation.The achievement in research of domestic this aspect is more, apparent in clastic reservoir rock and volcanic rock reservoir application effect.Fault
Lai trainings etc., 2003 (southwestern petroleum journals) have studied is converted to pseudo- capillary pressure curve using nuclear magnetic resonance T 2 spectrum, to calculate
The method of saturation degree；Since 2000, the combination such as the beginning of spring of rectifying, Mao Zhiqiang, Sun Zhongchun, He Dan, Xiao Liang Junggar Basin low-resistance,
The characteristics of low hole, low permeability sandstone reservoirs and volcanic rock reservoir, converts capillary pressure curve to application NMR logging data
Method is studied, it is proposed that the method for segmentation power exponent conversion, and national inventing patent (2012) is obtained, in clast
Preferable geological effect has been seen in rock, volcanic rock reservoir saturation computation.Another method assumes that reservoir height is sufficiently large,
Oil saturation is estimated with the irreducible water saturation that nuclear magnetic resonance log obtains.
However, the characteristics of compact oil reservoir has source storage one, and non-buoyancy is at hiding, without specific oil-water interfaces, the first
Method can not be applied directly.Since fine and close oily reservoir is based on nano-pore, can not flow under formation conditions, fluid almost all
It is constraint fluid, second method can not also use.That is, under existing technical conditions, oil saturation calculates
It is the fine and close oily technical barrier of reservoir characterization and the critical issue of urgent need to resolve.
Invention content
The main purpose of the present invention is to provide a kind of methods for the oil saturation calculating fine and close oily reservoir.
To achieve the goals above, according to an aspect of the invention, there is provided a kind of calculating hydrophilic or neutral wetting cause
The method of the oil saturation of close oil reservoir, includes the following steps：Using nuclear magnetic resonance logging instrument gathered data, and through data
Processing obtains lateral relaxation time T2Spectrum；Determine that hydrophilic or neutral wetting fine and close oily reservoir corresponds to oil-containing pore throat radius lower limit
Lateral relaxation time threshold value；According to lateral relaxation time T2The fine and close oily reservoir of spectrum and lateral relaxation time threshold value Continuous plus
Oil saturation.
Further, lateral relaxation time T is obtained2The method of spectrum includes：Utilize the minimum echo interval of Nuclear Magnetic Resonance
The log data of the fine and close oily reservoir of acquisition, and utilize the lateral relaxation time T of log data acquisition proton2Spectrum.
Further, two methods are selected to determine that lateral relaxation time threshold value, first method are the hydrogen-frees of core sample
Desaturation and nuclear magnetic resonance translocation method, second method are sealing core drilling analysis oil saturation data and nuclear magnetic resonance log T2Threshold value
Iterative method.
Further, the hydrogen-free desaturation of core sample includes with the step of nuclear magnetic resonance translocation method：It is retained hydrogen-free rock core
Processing；The Nuclear Magnetic Resonance Measurement being retained during hydrogen-free desaturation；The identification of water spectrum and T2The determination of threshold value.
Further, sealing core drilling analysis oil saturation data and nuclear magnetic resonance log T2The step of threshold iterative method includes：
The joint for carrying out saturation analysis data using every meter of not less than 3 data lacunarity analysis data playbacks；Utilize microresistivity
Scanning imagery data carries out playback fine tuning to the rock core of fine and close oily reservoir；Lateral relaxation time threshold value is determined using iterative method, is counted
Calculate T when mean square error minimum2Value is saturation computation threshold value A T2, and its calculation formula is as follows：Wherein, WT2 (j) is j-th of iteration T2The side of threshold value calculates error, and n is oil-containing
The number of saturation degree experimental data, SOiFor the saturation degree measurement data of i-th of sampling point, SSOjiFor j-th of iteration T2The of threshold value
I calculating saturation degree, calculation formula are as follows：
When wherein AT (j) is that oil saturation starts nuclear magnetic resonance transverse relaxation
Between, ms；ATS is the nuclear magnetic resonance transverse relaxation time to count of effecive porosity；ATD is that the nuclear magnetic resonance of effecive porosity is lateral
Relaxation terminates the time.
Further, first method and second method use respectively；Or first method and second method are simultaneously
Using.
Further, according to lateral relaxation time T2The oil-containing of spectrum and the fine and close oily reservoir of lateral relaxation time threshold calculations is full
Formula with degree is：
It applies the technical scheme of the present invention, this method is based on nuclear magnetic resonance log data, by determining fine and close oil storage
Layer is in hydrophilic or neutral wetting, the corresponding nuclear magnetic resonance transverse relaxation minimum time threshold of oil-containing pore throat radius lower limit
Value, so as to form a kind of completely new lateral relaxation time T using nuclear magnetic resonance2It is full that spectrum directly calculates fine and close oily reservoir oil-containing
With the method for degree.
Description of the drawings
The accompanying drawings which form a part of this application are used to provide further understanding of the present invention, and of the invention shows
Meaning property embodiment and its explanation are not constituted improper limitations of the present invention for explaining the present invention.In the accompanying drawings：
The flow of the method for the oil saturation for the fine and close oily reservoir of calculating that Fig. 1 is provided by the application embodiment is illustrated
Figure；
Fig. 2 is the experimental result that the hydrogen-free desaturation of one piece of core sample is obtained with nuclear magnetic resonance translocation method；
Fig. 3 is the playback figure of a well sealing core drilling saturation analysis data well section；
Fig. 4 is the Analysis of Mean Square Error figure that a well sealing core drilling well section is iterated to calculate using different AT2 values；
Fig. 5 is the determining AT2 and nuclear magnetic resonance log T of a well application2Compose the oil saturation figure calculated；And
Fig. 6 is 3 mouthfuls of wells, 59 groups of calculating oil saturations and experimental analysis saturation degree error analysis figure.
Specific implementation mode
It should be noted that in the absence of conflict, the features in the embodiments and the embodiments of the present application can phase
Mutually combination.The application is described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.
It should be noted that term used herein above is merely to describe specific implementation mode, and be not intended to restricted root
According to the illustrative embodiments of the application.As used herein, unless the context clearly indicates otherwise, otherwise singulative
It is also intended to include plural form, additionally, it should be understood that, when in the present specification using term "comprising" and/or " packet
Include " when, indicate existing characteristics, step, operation, device, component and/or combination thereof.
The present invention is built on the basis of rock core desaturation nuclear magnetic resonance experiment data and continuous sealing core data are analyzed
The corresponding nuclear magnetic resonance transverse relaxation minimum time threshold value of determining fine and close oil reservoir minimum oil-containing pore throat radius is found, to be formed
A kind of completely new method for directly calculating fine and close oil reservoir oil saturation using nuclear magnetic resonance lateral relaxation time wave spectrum.Such as
Shown in Fig. 1, this approach includes the following steps：It is obtained laterally using nuclear magnetic resonance logging instrument gathered data, and through data processing
Relaxation time T2Spectrum；When determining that hydrophilic or neutral wetting fine and close oily reservoir corresponds to the transverse relaxation of oil-containing pore throat radius lower limit
Between threshold value；According to lateral relaxation time T2The oil saturation of spectrum and the fine and close oily reservoir of lateral relaxation time threshold value Continuous plus.
For the present invention on the basis of log data of fine and close oily reservoir, fine and close oil reservoir minimum oil-containing pore throat radius is corresponding
Nuclear magnetic resonance transverse relaxation minimum time threshold value, so as to form a kind of completely new lateral relaxation time T using nuclear magnetic resonance2
The method that spectrum directly calculates fine and close oily reservoir oil saturation.
The method of the oil saturation according to the fine and close oily reservoir of calculating provided by the invention is described in more detail below
Illustrative embodiments.However, these illustrative embodiments can be implemented by many different forms, and should not be by
It is construed to be only limited to embodiments set forth herein.It should be understood that thesing embodiments are provided so that this Shen
Disclosure please is thoroughly and complete, and the design of these illustrative embodiments is fully conveyed to ordinary skill people
Member.
First, using nuclear magnetic resonance logging instrument gathered data, and lateral relaxation time T is obtained through data processing2Spectrum.It should
It is general to be adopted using the minimum echo interval that instrument provide the characteristics of development according to fine and close oily reservoir nanoaperture in step
Collection, and control and test the speed, the signal-to-noise ratio of well-log information is improved, the lateral relaxation time T of proton is obtained with well-log information2Compose (i.e. T2Wave
Spectrum).
Then, it is determined that when hydrophilic or neutral wetting fine and close oily reservoir corresponds to the transverse relaxation of oil-containing pore throat radius lower limit
Between threshold value.
The present invention provides two methods：A kind of hydrogen-free desaturation for core sample and nuclear magnetic resonance translocation method.It is another
Kind is that sealing core drilling analyzes oil saturation data and nuclear magnetic resonance log T2Threshold iterative method.The former is suitable for no system sealing core drilling
The case where data, can be completed with conventional coring, and the latter is suitable for having the case where system sealing core drilling.Two methods also can be simultaneously
Using mutually confirmation, to improve saturation degree T2The determination precision of threshold value.
Wherein, the hydrogen-free desaturation of core sample includes with nuclear magnetic resonance translocation method experimental procedure：1., water conservation hydrogen-free rock core
Processing；2., water conservation hydrogen-free desaturation during Nuclear Magnetic Resonance Measurement；3., the identification of water spectrum and the determinations of T2 threshold values.The experiment
Core be that water conservation obtains substantially without the NMR water spectrum containing oil samples under the conditions of hydrocarbon.The characteristics of fine and close oil reservoir is to receive
Based on metre hole gap, oil saturation is higher, containing the lower water preservation of content in oil samples in the smaller interstitial space of pore diameter
It is interior, it is relatively easy to maintain.In addition, due to reservoir samples densification, mud filtrate invasion is shallower during coring, and easily obtaining has representative
The sample of property.
Laboratory sample drills through：The full-hole core that coring obtains Cord blood at a temperature of 30 DEG C, chooses representative
Rock core 1 inch of sample is drilled through with liquid nitrogen, removing both ends has a part centainly polluted, intermediate 4cm samples as laboratory sample,
Ensure the anhydrous intrusion of specimen sample, evaporation.
Measure the remaining oil before non-washing oil, water two-phase NMR spectrum, spectral lines in Fig. 2.It is worth noting that by
It is that conventional coring obtains in sample, in this case, the light components of crude oil are lost, but this is to complete aqueous spectrum
Obtaining influences less.
It is retained hydrogen-free desaturation and NMR spectrum measures：Fine and close oil reservoir samples permeability is extremely low, overburden permeability
Usually less than 0.1md cannot achieve with the method desaturation of displacement.Using the method desaturation of carbon dioxide washing oil, first wash away
Oil gas in big pore throat washes away oil gas in smaller hole larynx again, in this course the corresponding nuclear magnetic resonance for measuring core sample
Wave spectrum obtains the remaining water spectrum for being substantially free of hydro carbons until washing away the hydro carbons in core sample substantially, in Fig. 2 × spectrum of symbol
Line.
The identification of water spectrum and T2The determination of threshold value：The feature of the remaining water spectrum of analysis, determines aqueous volume, obtains oil-containing saturation
Spend the T calculated2Threshold value.T is obtained from remaining completely aqueous spectrum2Threshold value A T2For 6ms.
In another preferred embodiment of the present invention, surveyed with nuclear-magnetism using sealing core drilling analysis oil saturation data
Well T2The step of threshold iterative method includes：1., the accurate playback of saturation data；2., iterative method determine saturation computation transverse direction
Relaxation time T2Threshold value.
The accurate playback of saturation data：First, with every meter saturation degree is carried out not less than 3 data lacunarity analysis data
Analyze the joint playback of data；Then, the fine tuning of the playback of rock core is carried out with micro resistor data, it is ensured that playback misses
Poor less 0.1m (Fig. 3).In Fig. 3, CALi, GR and SP are lithology curve, and for dividing reservoir and non-reservoir, wherein CALi is well
Diametal curve, GR are Natural Gamma-ray Logging Curves, and SP is nutural potential logging curve；RI, RXO and RT are resistivity curve, are used for
Judge that the oiliness of reservoir, wherein RXO are flushed zone formation resistivity；DEN, CNL and AC are porosity curve, for calculating storage
The size of layer porosity, wherein DEN are density curve；T2 is NMR spectrum.
Sealing core drilling analyzes oil saturation data and nuclear magnetic resonance log T2The step of threshold iterative method includes：Not using every meter
Less than 3 data lacunarity analysis data carry out the joint playback of saturation analysis data；It is provided using micro resistor
Expect that the rock core to fine and close oily reservoir carries out playback fine tuning；Lateral relaxation time threshold value is determined using iterative method, calculates mean square error
T when minimum2Value is saturation computation threshold value A T2, and its calculation formula is as follows：Its
In, WT2 (j) is that the side of j-th of iteration T2 threshold value calculates error, and n is the number of oil saturation experimental data, SOi i-th
The saturation degree measurement data of a sampling point, SSOji are i-th of calculating saturation degree of j-th of iteration T2 threshold value, and calculation formula is such as
Under：
When wherein AT (j) is that oil saturation starts nuclear magnetic resonance transverse relaxation
Between, ms；ATS is the nuclear magnetic resonance transverse relaxation time to count of effecive porosity；ATD is that the nuclear magnetic resonance of effecive porosity is lateral
Relaxation terminates the time.
Wherein, first method and second method use respectively；Or first method and second method are applied simultaneously.
Calculate the T of mean square error minimum2Value is determining T2Saturation computation threshold value A T2.Fig. 4 is a well sealing core drilling
Well section applies different AT2Be worth the mean square error calculated, when mean square error minimum corresponding AT2For 6ms, with core experiment knot
Fruit is completely the same.
Finally, the oil-containing according to the fine and close oily reservoir of lateral relaxation time wave spectrum and lateral relaxation time threshold value Continuous plus is full
And degree.
Using determining AT2The continuous T obtained with nuclear magnetic resonance log2The full of each measuring point is calculated according to the following formula in wave spectrum
And degree：
Wherein, So is the oil saturation of the fine and close oily reservoir, φiIt is corresponded to for i-th millisecond of NMR relaxation time
Hole relative volume, AT2 be the lateral relaxation time threshold value, ATS be effecive porosity nuclear magnetic resonance transverse relaxation rise
Evaluation time, ms；ATD is that the nuclear magnetic resonance transverse relaxation of effecive porosity terminates time, ms.
Fig. 5 is the continuous T that a well application determining AT2 and nuclear magnetic resonance log are obtained2Wave spectrum calculates the reality of saturation degree
Example.Result of calculation is compared with measured result, and the form of two kinds of results is consistent, and the relative error for calculating saturation degree is relatively small.3 mouthfuls
Well sealing core drilling saturation degree is compared with the saturation degree that the present invention calculates, and is calculated error and is mainly distributed within 10%, average absolute
Error is 2.3%, and computational accuracy is high, is fully able to meet the required precision of reserves calculating.In Fig. 5, CALi, GR and SP are lithology
Curve, for dividing reservoir and non-reservoir, wherein CALi is well curve, and GR is Natural Gamma-ray Logging Curves, and SP is nature electricity
Position log；RI, RXO and RT are resistivity curve, for judging that the oiliness of reservoir, wherein RXO are flushed zone stratum electricity
Resistance rate；DEN, CNL and AC are porosity curve, and for calculating the size of reservoir porosity, wherein DEN is density curve；T2 is
NMR spectrum.
The techniqueflow of the present invention will be described in detail by taking a fine and close oilfield as an example, but should not be understood as below
To the present invention can practical range restriction.
Illustrate that block is the fine and close oilfield of the Junggar Basin Permian System one.Fine and close oil reservoir is the thin of salified lacustrine environment
Grain deposition, principal lithologic are clastic rock and carbonate rock transitionality rock class.The porosity of reservoir be mainly distributed on 6~16% it
Between, overburden permeability is generally less than 0.1md, for typical fine and close oily reservoir.The oil saturation of reservoir is generally higher, analyzes number
Mostly it is higher than 70% according to oil saturation.The more well formation testings of whole district's block have higher yield without natural production capacity after volume fracturing.Entirely
All fine and close oilfield formation testing well sections in area do not produce water, and formation water resistivity money can not be obtained by calculating saturation degree with resistivity method
Material.All fine and close oil wells of the whole district have carried out nuclear magnetic resonance log.Exploration initial stage is full using the nuclear magnetic resonance log of conventional reservoir
With degree computational methods, the saturation degree error of calculating is larger.It is unable to meet production the technology requirement of fine and close oily oiliness characterization.It presses
Preferably solves the technical barrier of saturation computation according to method and technology provided by the invention.
Specific implementation mode and implementing procedure are：
1) it, according to fine and close oily reservoir nanoaperture development the characteristics of, is acquired using minimum echo interval, and control and test the speed,
Qualified NMR logging data is obtained, Inversion Calculation obtains the lateral relaxation time T of proton2Wave spectrum.
2) it, chooses representational rock core and carries out hydrogen-free desaturation and nuclear magnetic resonance translocation experiment
Laboratory sample drills through：The full-hole core that coring obtains Cord blood at a temperature of 30 DEG C, chooses representative
Rock core 1 inch of sample is drilled through with liquid nitrogen, removing both ends has a part centainly polluted, intermediate 4cm samples as laboratory sample,
Ensure the anhydrous intrusion of specimen sample, evaporation.First, measure the remaining oil before non-washing oil, water two-phase NMR spectrum.It is worth
Illustrate, since sample is that conventional coring obtains, in this case, the light components of crude oil are lost, but this is right
The acquisition of complete aqueous spectrum influences little.
It is retained hydrogen-free desaturation and NMR spectrum measures：Fine and close oil reservoir samples permeability is extremely low, overburden permeability
Usually less than 0.1md cannot achieve with the method desaturation of displacement.Using the method desaturation of carbon dioxide washing oil, first wash away
Oil gas in big pore throat washes away oil gas in smaller hole larynx again, in this course the corresponding nuclear magnetic resonance for measuring core sample
Wave spectrum obtains the remaining water spectrum for being substantially free of hydro carbons until washing away the hydro carbons in core sample substantially.
The identification of water spectrum and T2The determination of threshold value：The feature of the remaining water spectrum of analysis, determines aqueous volume, obtains oil-containing saturation
Spend the T calculated2Threshold value.T is obtained from remaining completely aqueous spectrum2Threshold value A T2.
The densification oilfield has chosen 4 pieces of samples and carries out hydrogen-free desaturation and nuclear magnetic resonance translocation experiment, respectively sand formation cuttings
Yun Yan, cloud bits siltstone, feldspar landwaste siltstone and cloud matter siltstone.It is true that experiment is now introduced by taking the experiment of cloud matter siltstone as an example
Determine T2The method of threshold value A T2.The porosity of laboratory sample is 13.4%, and overburden permeability 0.09md, experimental result is shown in attached drawings
2.In figure：□T2Spectrum is the T before washing oil2Spectrum；◇ is T of the washing oil after 2 days2Spectrum；× water the spectrum obtained after 6 days for washing oil.Using note
The method of the mating measurement of helium porosity can detect light components volatile quantity and wash away the pore volume of crude oil.Before washing oil, helium is noted
It is 3.4% to measure porosity, is 10.04% by the porosity that nuclear magnetic resonance obtains, the NMR spectrum the oil-bearing characteristics of acquisition
Obviously.Hereafter, a nuclear-magnetism, the note mating measurement of helium are carried out per washing oil one day, washing oil measurement result two days later and magnetic resonance spectroscopy
It has been shown that, sample still have the oil-bearing characteristics, until washing oil after 6 days, obtains substantially completely aqueous nuclear-magnetism spectrum.At this point, sample
Basic unstressed configuration, nuclear-magnetism spectrum water spectrum signature is apparent, and the measured value of note helium porosity is 10.94%, obtains the oil-containing saturation of sample
Degree is 82%.It is 6ms from the aqueous AT2 threshold values obtained of composing.
3), the systematic sealing core drilling saturation degree survey data in the area analyzes oil saturation data using sealing core drilling
With nuclear magnetic resonance log T2Threshold iterative method further verifies core experiment result.
The accurate playback of saturation data：First, with every meter saturation degree is carried out not less than 3 data lacunarity analysis data
Analyze the joint playback of data；Then, the fine tuning of core Location is carried out with micro resistor data, it is ensured that playback error
No more than 0.1m (Fig. 3).In Fig. 3, first is respectively that well curve, Natural Gamma-ray Logging Curves and nutural potential logging are bent
Line, second are depth track, and third road is three Resistivity logs, and the 4th is tri-porosity logging curve, and the 5th is
Nuclear magnetic resonance log curve and core analysis porosity (scatterplot), the 6th is the oil saturation (scatterplot) of analysis.
Iterative method determines saturation computation lateral relaxation time T2Threshold value：It is iterated calculating mean square error by following equation
Difference：
In formula：AT2 (j) is j-th of iteration T2The side of threshold value calculates error；
N is the number of oil saturation experimental data；
SOi is the saturation degree measurement data of i-th of sampling point；
SSOji is j-th of iteration T2I-th of calculating saturation degree of value.
Calculate the T of mean square error minimum2Value is determining T2Saturation computation threshold value A T2.This mouthful of well sealed coring well of Fig. 4
The mean square error that the different AT2 values of Duan Yingyong calculate, when mean square error minimum, corresponding AT2 was 6ms, complete with core experiment result
It is complete consistent.
4), the continuous T obtained using determining AT2 and nuclear magnetic resonance log2Wave spectrum presses the following equation Continuous plus whole district
The saturation degree of each well：
Wherein, So is the oil saturation of the fine and close oily reservoir, φiIt is corresponded to for i-th millisecond of NMR relaxation time
Hole relative volume, AT2 be the lateral relaxation time threshold value, ATS be effecive porosity nuclear magnetic resonance transverse relaxation rise
Evaluation time, ms；ATD is that the nuclear magnetic resonance transverse relaxation of effecive porosity terminates time, ms.
Fig. 5 is the continuous T that a well application determining AT2 and nuclear magnetic resonance log are obtained2Wave spectrum calculates the reality of saturation degree
Example.In figure, the 6th is the saturation degree calculated and sealing core drilling saturation degree (scatterplot) comparison diagram, in terms of comparing result, two kinds of sides
The saturation degree that method obtains has preferable consistency, and precision is higher.In Fig. 5, first is respectively well curve, natural gamma
Log and nutural potential logging curve, second are depth track, and third road is three Resistivity logs, and the 4th is three
Porosity logging curve, the 5th surveys T for nuclear magnetic resonance2Spectrum, the 6th is that the oil saturation of calculating and the oil-containing of analysis are satisfied
With degree (scatterplot).
3 mouthfuls of local area has sealing core drilling saturation analysis data, totally 59 pieces of samples.It calculates saturation degree and analysis saturation degree is missed
Poor analysis chart is shown in Fig. 6.3 mouthfuls of well sealing core drilling saturation degrees are compared with the saturation degree that the present invention calculates, and are calculated error and are mainly distributed on
Within 10%, mean absolute error 2.3%, computational accuracy is high, is fully able to meet the required precision of reserves calculating.
As can be seen from the above embodiments, the above-mentioned example of the present invention realizes following technique effect：This method is with nuclear-magnetism
Based on the log data that resonates, by determining fine and close oily reservoir under hydrophilic or neutral wetting, oil-containing pore throat radius
Corresponding nuclear magnetic resonance transverse relaxation minimum time threshold value is limited, is relaxed so as to form a kind of completely new transverse direction using nuclear magnetic resonance
Henan time T2The method that spectrum directly calculates fine and close oily reservoir oil saturation.
It these are only the preferred embodiment of the present invention, be not intended to restrict the invention, for those skilled in the art
For member, the invention may be variously modified and varied.Any modification made by all within the spirits and principles of the present invention,
Equivalent replacement, improvement etc., should all be included in the protection scope of the present invention.
Claims (3)
1. a kind of method for the oil saturation calculating fine and close oily reservoir, which is characterized in that include the following steps：
Lateral relaxation time T is obtained using nuclear magnetic resonance logging instrument gathered data, and through data processing2Spectrum；
Determine that hydrophilic or neutral wetting the fine and close oily reservoir corresponds to the lateral relaxation time threshold of oil-containing pore throat radius lower limit
Value；
According to the lateral relaxation time T2The oil-containing of fine and close oily reservoir described in spectrum and the lateral relaxation time threshold value Continuous plus
Saturation degree,
Wherein, one of following two methods are selected to determine the lateral relaxation time threshold value, first method is core sample
Hydrogen-free desaturation and nuclear magnetic resonance translocation method, second method are sealing core drilling analysis oil saturation data and nuclear magnetic resonance log T2
Threshold iterative method,
The hydrogen-free desaturation of the core sample includes with the step of nuclear magnetic resonance translocation method：It is retained the processing of hydrogen-free rock core；Water conservation
Nuclear Magnetic Resonance Measurement during hydrogen-free desaturation；The identification of water spectrum and T2The determination of threshold value,
The sealing core drilling analysis oil saturation data and nuclear magnetic resonance log T2The step of threshold iterative method includes：Not using every meter
Less than 3 data lacunarity analysis data carry out the joint playback of saturation analysis data；It is provided using micro resistor
Expect that the rock core to the fine and close oily reservoir carries out playback fine tuning；The lateral relaxation time threshold value is determined using iterative method, is calculated
T when mean square error minimum2Value is saturation computation threshold value A T2, and its calculation formula is as follows：
Wherein, WT2 (j) is j-th of iteration T2The side of threshold value calculates error, and n is the number of oil saturation experimental data, SOi
For the saturation degree measurement data of i-th of sampling point, SSOjiFor j-th of iteration T2I-th of calculating saturation degree of threshold value, calculation formula
It is as follows：
Wherein AT (j) is that oil saturation starts nuclear magnetic resonance lateral relaxation time, ms；ATS is that the nuclear-magnetism of effecive porosity is total
Shake transverse relaxation time to count, ms；ATD be effecive porosity nuclear magnetic resonance transverse relaxation terminate the time, ms,
According to the lateral relaxation time T2The oil-containing saturation of fine and close oily reservoir described in spectrum and the lateral relaxation time threshold calculations
The formula of degree is：
Wherein, So is the oil saturation of the fine and close oily reservoir, φiFor i-th millisecond of NMR relaxation time corresponding hole
Relative volume, AT2For the lateral relaxation time threshold value, ATS is the nuclear magnetic resonance transverse relaxation time to count of effecive porosity,
ms；ATD is that the nuclear magnetic resonance transverse relaxation of effecive porosity terminates time, ms.
2. according to the method described in claim 1, it is characterized in that, obtaining the lateral relaxation time T2The method of spectrum includes：Profit
The log data of fine and close oily reservoir is acquired with the minimum echo interval of Nuclear Magnetic Resonance, and is obtained using the log data
The lateral relaxation time T of proton2Spectrum.
3. according to the method described in claim 1, it is characterized in that, the first method and the second method make respectively
With；Or the first method and the second method are applied simultaneously.
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| CN108896598B (en) * | 2018-04-17 | 2021-05-28 | 中国石油天然气股份有限公司 | Method and device for determining content of compact oil |
| CN109779619B (en) * | 2019-01-21 | 2023-02-28 | 中国石油天然气集团有限公司 | Method for calculating stratum water saturation through nuclear magnetic T2 spectrum |
| CN110487835B (en) * | 2019-09-18 | 2022-04-05 | 西南石油大学 | Novel method for calculating reservoir saturation index of compact oil and gas reservoir |
| CN111007230B (en) * | 2019-11-21 | 2022-03-29 | 中国石油天然气股份有限公司 | Method for quantitatively evaluating oil content of low-porosity compact oil reservoir of continental-phase lake basin |
| CN114414609B (en) * | 2022-01-13 | 2022-11-01 | 东北石油大学 | Experiment method for calculating influence of invaded liquid on shale oil momentum based on nuclear magnetic T2 spectrum |
| CN114660668B (en) * | 2022-02-18 | 2024-09-03 | 中国石油大学(华东) | Shale porosity overburden pressure correction method based on fracture effect |
| CN115420766B (en) * | 2022-09-06 | 2023-05-19 | 东北石油大学 | Based on T 2 Method for measuring distribution of residual oil in sandstone water injection oil extraction by spectrum analysis |
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