CN104634804B - A kind of method utilizing nuclear magnetic resonance T 2 spectrum to determine reservoir relative permeability - Google Patents

Abstract

A kind of method determining the biphase relative permeability of oilfield reservoir, belongs to oilfield reservoir assessment technique field.Select serial representativeness rock core, and rock core is carried out nuclear magnetic resonance, NMR T2 experiment and relative permeability determination experiment, and obtain rock core nuclear magnetic resonance T 2 spectrum data, relative permeability data；Cumulative porosity degree spectrum is calculated according to nuclear magnetic resonance T 2 spectrum data, ask for different relaxation time correspondence cumulative porosity amount and account for the percentage ratio of total pore space amount, then according to nuclear magnetic resonance T 2 spectrum data and the relative permeability data of core sample, nuclear magnetic resonance T 2 spectrum is converted to pseudo-relative permeability data；The pseudo-relative permeability data of gained contrast with actual permeability saturation curve, carry out coefficient C balance correction, reach two kinds of curves overlapped by balance correction, complete standardization；Carry out pseudo-permeability saturation curve graphic plotting.The present invention is to implement reservoir productivity prediction in well log interpretation evaluation procedure to lay a good foundation.

Description

A kind of method utilizing nuclear magnetic resonance T 2 spectrum to determine reservoir relative permeability

Technical field

The present invention relates to a kind of method determining the biphase relative permeability of oilfield reservoir, belong to oilfield reservoir Assessment technique field.

Background technology

Permeability saturation curve data is the important parameter in reservoir engineering and numerical simulation calculation, it is possible to Calculate oil well output and mobility ratio, determine the saturation distribution of profit in reservoir, oil water boundary position And produce the Guan Bi height of pure oil.Accurately asking for relative permeability is that oil field development calculates, dynamically analyzes And the element task of evaluating reservoir.

Measuring permeability saturation curve in laboratory is all based on rock core injection experiments, is broadly divided into Steady state method and cold store enclosure.

Steady state method is that according to certain ratio, water-oil phase fluid is injected rock core with constant injection rate, In rock core, on every bit, the flowing of two-phase fluid all reaches stable, the saturation of the most each phase, flowing speed Degree and barometric gradient change with distance in rock core the most in time.Now, the pressure reduction at rock core two ends, often The saturation of one phase, flow can be measured and obtain, then by Darcy's law and relative permeability definition The oil under this water saturation, water relative permeability can be calculated.

Cold store enclosure is to come based on Lie Weierte water drive oil theory by Bake, moves according to external water flood State determines the method for rock sample relative permeability, symmetrical external drive method, compared with steady state method, oil, Water saturation and distribution thereof change with distance in time.

In sum, above prior art at least has the following disadvantages:

Steady state method: the rock core port of export causes saturation gradient, i.e. end effect due to capillary pressure effect, Experiment pressure reduction need to be increased or use relatively long cores to eliminate or alleviate the impact of end effect；Steady state method pair Middle wettability well adapting to property of rock；Shortcoming is to measure excessive cycle.

Cold store enclosure: the cycle of measuring is shorter, needs high speed displacement, it is possible to elimination end effect, but meeting Strengthen arrival end effect, and data process more miscellaneous.

Summary of the invention

Permeate in order to relative obtained by solving in prior art laboratory end effect and measuring cycle length Rate is the most representative and ageing, and the rock core that existence cannot be carried out displacement test because of densification can not obtain The problem obtaining permeability saturation curve.Embodiments provide a kind of based on nuclear magnetic resonance T 2 spectrum The method determining oil field region reservoir relative permeability, for the biphase relative permeability of actual reservoir really Fixed, lay a good foundation for well logging is implemented the conversion of reservoir dynamic and static state parameters and capability forecasting.Described Technical scheme is as follows:

A kind of method utilizing nuclear magnetic resonance T 2 spectrum to determine reservoir relative permeability, according to following steps Operate:

1) select serial representativeness rock core, and rock core is carried out nuclear magnetic resonance, NMR T2 experiment and relative infiltration Rate determination experiment, and obtain rock core nuclear magnetic resonance T 2 spectrum data, relative permeability data；

2) calculate cumulative porosity degree spectrum according to nuclear magnetic resonance T 2 spectrum data, ask for the different relaxation time pair Cumulative porosity amount is answered to account for the percentage ratio of total pore space amount, i.e. S_i；

$S_i=\frac{{\∫}_a^b\mathrm{Ad}\left(T2\right)}{{\∫}_a^d\mathrm{Ad}\left(T2\right)}$

In formula:

A is T2 spectral amplitude,

T2 is the T2 that nuclear-magnetism is measured, and unit is ms,

A, d are respectively the initial value in nuclear magnetic resonance T 2 spectrum relaxation time, stop value,

B is the relaxation time of different aperture degree component；

3) then according to nuclear magnetic resonance T 2 spectrum data and the relative permeability data of core sample, utilize Nuclear magnetic resonance T 2 spectrum is converted to pseudo-relative permeability data by invention formula, specifically according to following invention Formula converts:

$k_{\mathrm{rw}}=\frac{{\∫}_0^{S_i}{\left(T2\right)}^2\mathrm{dS}}{{\∫}_0^1{\left(T2\right)}^2\mathrm{dS}}$

$k_{\mathrm{ro}}=\frac{{\∫}_{S_i}^1{\left(T2\right)}^2\mathrm{dS}}{{\∫}_0^1{\left(T2\right)}^2\mathrm{dS}}$

In formula:

K_rwFor aqueous phase relative permeability, dimensionless,

K_roFor oil relative permeability, dimensionless,

T2 is the T2 that nuclear-magnetism is measured, and unit is ms,

S_iThe percentage ratio of total pore space amount is accounted for for different relaxation time correspondence cumulative porosity amounts.

4) according to pseudo-relative permeability data and the actual permeability saturation curve pair of step 3) gained Ratio, carries out coefficient C balance correction, reaches two kinds of curves overlapped by balance correction, completes standardization Process；

5) pseudo-permeability saturation curve graphic plotting is carried out.

Concrete, rock core nuclear-magnetism T2 described in described step (1) tests according to " rock sample nuclear magnetic resonance, NMR Experiment Parameter room specifications of surveys SY/T6490-2007 " flow process that specifies of standard carries out.

Concrete, relative permeability described in described step (1) is tested according to " rock is biphase relatively Mensuration SY/T5345-2007 of permeability curve " flow process that specifies of standard carries out.

Concrete, described based on nuclear magnetic resonance T 2 spectrum with permeability saturation curve relation, utilize and invent Formula asks for pseudo-relative permeability, it is thus achieved that pseudo-permeability saturation curve and experiment permeability saturation curve Standardization translation coefficient.

Further, described step (2) utilizes nuclear magnetic resonance T 2 spectrum data to calculate cumulative porosity degree spectrum, Ask for different relaxation time correspondence cumulative porosity amount and account for the percentage ratio of total pore space amount.

Further, described step (3) utilizes nuclear magnetic resonance T 2 spectrum curve and wetting phase (profit) Relative permeability numerical relation, utilizes invention formula to ask for pseudo-relative permeability.

Further, described step (4) utilizes pseudo-relative permeability numerical value and actual relative permeability Value contrast, determines standardization translation coefficient.

Further, described step (2) utilizes nuclear magnetic resonance T 2 spectrum data to calculate cumulative porosity degree spectrum, Ask for different relaxation time correspondence cumulative porosity amount and account for the percentage ratio of total pore space amount.Specifically will be according to will be as Under:

$S_i=\frac{{\∫}_a^b\mathrm{Ad}\left(T2\right)}{{\∫}_a^d\mathrm{Ad}\left(T2\right)}$

In formula:

A is T2 spectral amplitude,

T2 is the T2 that nuclear-magnetism is measured, and unit is ms,

A, d are respectively the initial value in nuclear magnetic resonance T 2 spectrum relaxation time, stop value,

B is the relaxation time of different aperture degree component；

Further, nuclear magnetic resonance T 2 spectrum curve is utilized to calculate oil phase phase described in described step (3) To permeability and aqueous phase relative permeability, specifically will carry out according to by following invention formula,

$k_{\mathrm{rw}}=\frac{{\∫}_0^{S_i}{\left(T2\right)}^2\mathrm{dS}}{{\∫}_0^1{\left(T2\right)}^2\mathrm{dS}}$

$k_{\mathrm{ro}}=\frac{{\∫}_{S_i}^1{\left(T2\right)}^2\mathrm{dS}}{{\∫}_0^1{\left(T2\right)}^2\mathrm{dS}}$

K_rwFor aqueous phase relative permeability, dimensionless,

K_roFor oil relative permeability, dimensionless,

T2 is the T2 that nuclear-magnetism is measured,

S_iThe percentage ratio of total pore space is accounted for for different relaxation time corresponding aperture porosity components.

Further, pseudo-permeability saturation curve and actual experiment are utilized described in described step (4) Permeability saturation curve contrasts, and determines coefficient C, reaches two kinds of curves overlapped by balance correction, ask Take the amount of moving left and right and be C value.

The technical scheme that the embodiment of the present invention provides has the benefit that sets up nuclear magnetic resonance, NMR curve With permeability saturation curve transformational relation, nuclear magnetic resonance T 2 spectrum is converted to pseudo-permeability saturation curve Value；Utilize pseudo-permeability saturation curve and the contrast of actual experiment permeability saturation curve, by translation school Just reach two kinds of curves overlapped, determine coefficient C.Achieve static parameter inverting dynamic parameter, utilize Nuclear magnetic resonance T 2 spectrum calculates reservoir relative permeability, it is possible to solve laboratory end effect in prior art Should be the most representative and ageing with relative permeability obtained by measurement cycle length, and exist because of densification Cannot be carried out the problem that the rock core of displacement test can not obtain permeability saturation curve.Comment for well log interpretation Implement reservoir productivity prediction during valency to lay a good foundation.

Accompanying drawing explanation

For the technical scheme being illustrated more clearly that in the embodiment of the present invention, embodiment will be described below The accompanying drawing used required in is briefly described；It should be evident that the accompanying drawing in describing below is only It is some embodiments of the present invention, for those of ordinary skill in the art, is not paying creativeness On the premise of work, it is also possible to obtain other accompanying drawing according to these accompanying drawings.

Fig. 1 is the method stream of the biphase permeability saturation curve of determination reservoir that the embodiment of the present invention provides Cheng Tu；

Fig. 2 is that the pseudo-permeability saturation curve that the embodiment of the present invention provides is real with rock core relative permeability Test the permeability saturation curve comparison diagram of acquisition.

Detailed description of the invention

For making the object, technical solutions and advantages of the present invention clearer, below in conjunction with accompanying drawing to this Invention embodiment is described in further detail.

Embodiment 1

See Fig. 1, embodiments provide a kind of method determining reservoir relative permeability, press Operate according to following steps:

Step one, chooses the serial rock core that can represent geologic feature, according to " rock sample nuclear magnetic resonance, NMR is joined Number laboratory measurement specifications SY/T6490-2007 " flow process that specify of standard carries out rock core nuclear-magnetism T2 reality Test, obtain nuclear-magnetism T2 spectrum；According to " mensuration SY/T of the biphase permeability saturation curve of rock 5345-2007 " flow process that specifies of standard carries out the experiment of rock biphase permeability saturation curve, and obtains Relative permeability experimental data.

Step 2, calculates cumulative porosity degree spectrum according to nuclear magnetic resonance T 2 spectrum data, asks for different relaxation Time correspondence cumulative porosity amount accounts for the percentage ratio of total pore space amount, i.e. S_i；

$S_i=\frac{{\∫}_a^b\mathrm{Ad}\left(T2\right)}{{\∫}_a^d\mathrm{Ad}\left(T2\right)}$

In formula:

A is T2 spectral amplitude,

T2 is the T2 that nuclear-magnetism is measured, and unit is ms,

A, d are respectively the initial value in nuclear magnetic resonance T 2 spectrum relaxation time, stop value,

B is the relaxation time of different aperture degree component；

Step 3, is converted to permeability saturation curve according to the nuclear magnetic resonance T 2 spectrum data of core sample, Utilize invention formula to ask for pseudo-relative permeability data, specifically calculate according to following invention formula,

$k_{\mathrm{rw}}=\frac{{\∫}_0^{S_i}{\left(T2\right)}^2\mathrm{dS}}{{\∫}_0^1{\left(T2\right)}^2\mathrm{dS}}$

$k_{\mathrm{ro}}=\frac{{\∫}_{S_i}^1{\left(T2\right)}^2\mathrm{dS}}{{\∫}_0^1{\left(T2\right)}^2\mathrm{dS}}$

K_rwFor aqueous phase relative permeability, dimensionless,

K_roFor oil relative permeability, dimensionless,

T2 is the T2 that nuclear-magnetism is measured,

S_iThe percentage ratio of total pore space is accounted for for different relaxation time corresponding aperture porosity components.

Step 4, utilizes pseudo-permeability saturation curve and the contrast of actual experiment permeability saturation curve, logical Cross balance correction and reach two kinds of curves overlapped, ask for the amount of moving left and right and be C value.

Step 5, carries out pseudo-permeability saturation curve graphic plotting in standard relative permeability template.

The method that the embodiment of the present invention provides, by carrying out nuclear-magnetism T2 to the rock core representing geologic feature Experiment, relative permeability experiment, obtain rock core nuclear-magnetism T2 spectrum and relative permeability data, utilize and send out Bright formula, sets up nuclear magnetic resonance, NMR curve and permeability saturation curve transformational relation, by nuclear magnetic resonance, NMR T2 Spectrum is converted to pseudo-permeability saturation curve value；Utilize that pseudo-permeability saturation curve is relative with actual experiment oozes Rate curve comparison, reaches two kinds of curves overlapped by balance correction, determines coefficient C thoroughly.

Embodiment 2

The embodiment of the present invention chooses the core sample of NW Hebei Nan Bao depression S_1 Formation reservoir.Described storage Floor district is by geologic sedimentation and diagenetic affects, and reservoir clay content is high, rock particles is thin, bury Deep and secondary pore growing, forms typical mid-deep strata low porosity permeability reservoir, chooses 4 pieces of core samples, 1 step provided determines the relative permeability of 4 pieces of core samples according to embodiments of the present invention.Specifically press Implement according to following steps.

It is first according to " rock sample nuclear magnetic resonance parameter laboratory measurement specification SY/T6490-2007 " mark The flow process of quasi-regulation carries out rock core nuclear-magnetism T2 experiment, obtains nuclear-magnetism T2 spectrum；According to " the biphase phase of rock Mensuration SY/T5345-2007 to permeability curve " flow process that specifies of standard carries out the biphase phase of rock Permeability curve is tested, and obtains relative permeability experimental data.

Secondly calculate cumulative porosity degree spectrum according to nuclear magnetic resonance T 2 spectrum data, ask for the different relaxation time Corresponding cumulative porosity amount accounts for the percentage ratio of total pore space amount, i.e. S_i；

$S_i=\frac{{\∫}_a^b\mathrm{Ad}\left(T2\right)}{{\∫}_a^d\mathrm{Ad}\left(T2\right)}$

In formula:

A is T2 spectral amplitude,

T2 is the T2 that nuclear-magnetism is measured, and unit is ms,

A, d are respectively the initial value in nuclear magnetic resonance T 2 spectrum relaxation time, stop value,

B is the relaxation time of different aperture degree component；

Nuclear magnetic resonance T 2 spectrum data again according to core sample are converted to permeability saturation curve, profit Ask for pseudo-relative permeability data with invention formula, specifically calculate according to following invention formula,

$k_{\mathrm{rw}}=\frac{{\∫}_0^{S_i}{\left(T2\right)}^2\mathrm{dS}}{{\∫}_0^1{\left(T2\right)}^2\mathrm{dS}}$

$k_{\mathrm{ro}}=\frac{{\∫}_{S_i}^1{\left(T2\right)}^2\mathrm{dS}}{{\∫}_0^1{\left(T2\right)}^2\mathrm{dS}}$

K_rwFor aqueous phase relative permeability, dimensionless,

K_roFor oil relative permeability, dimensionless,

T2 is the T2 that nuclear-magnetism is measured,

S_iThe percentage ratio of total pore space is accounted for for different relaxation time corresponding aperture porosity components.

Finally, utilize pseudo-permeability saturation curve and the contrast of actual experiment permeability saturation curve, pass through Balance correction reaches two kinds of curves overlapped, asks for the amount of moving left and right and is C value.

Nuclear magnetic resonance T 2 spectrum curve is utilized to calculate Relative permeability curve value, with actual relative permeability value Contrast, asks for normalisation coefft C=3.21；Obtain calculating relative permeability value by standardization translation, Result is shown in Fig. 2.

Nuclear magnetic resonance T 2 spectrum and capillary pressure can reflect that reservoir microscopic void is tied to a certain extent Structure, having certain transformational relation, relative permeability and capillary pressure curve is all to pass through displacement test Obtain parameter, there is certain transformational relation, thus nuclear magnetic resonance T 2 spectrum and permeability saturation curve There is internal relation equally, all reflect the situation of RESERVOIR PORE STRUCTURE, and all relevant with capillary pressure, Meet rock physics understanding.By core experiment data it can be seen that nuclear magnetic resonance T 2 spectrum is with relative Relation between permeability curve can use formula quantificational expression of the present invention.

The embodiment of the present invention is provided and calculates reservoir relative permeability and core experiment relative permeability value Contrasting, as in figure 2 it is shown, wherein, X is saturation Sw, and unit is %；Y1 is that the present invention is real Executing the oil relative permeability value that example provides, unit is %.The aqueous phase that Y2 provides for the embodiment of the present invention Relative permeability value, unit is %.From figure 2 it can be seen that the reservoir that the embodiment of the present invention provides Relative permeability and core experiment relative permeability height matching, the two dependency is good, R²=0.96, Illustrate the determination reservoir relative permeability curve that the embodiment of the present invention provides method can accurately, reliable Determination reservoir relative permeability, have and well apply effect in actual reservoir calculates.

The invention described above embodiment sequence number, just to describing, does not represent the quality of embodiment.

As it has been described above, embodiments of the invention are explained, but as long as substantially Inventive point and effect without departing from the present invention can have a lot of deformation, and this is to those skilled in the art It is apparent from for Yuan.Therefore, such variation is also integrally incorporated in the protection model of the present invention Within enclosing.

Claims (2)

1. one kind utilizes the method that nuclear magnetic resonance T 2 spectrum determines reservoir relative permeability, it is characterised in that enter according to following steps Row operation:

1) select serial representativeness rock core, and rock core carried out nuclear magnetic resonance, NMR T2 experiment and relative permeability determination experiment, And obtain rock core nuclear magnetic resonance T 2 spectrum data and relative permeability data；

2) calculate cumulative porosity degree spectrum according to nuclear magnetic resonance T 2 spectrum data, ask for different relaxation time correspondence cumulative porosity amount Account for the percentage ratio of total pore space amount, i.e. S_i；

$S_i=\frac{{\∫}_a^{b}Ad\left(T2\right)}{{\∫}_a^{d}Ad\left(T2\right)}$

In formula:

A is T2 spectral amplitude,

T2 is the T2 that nuclear-magnetism is measured, and unit is ms,

A, d are respectively the initial value in nuclear magnetic resonance T 2 spectrum relaxation time, stop value,

B is the relaxation time of different aperture degree component；

3) then according to nuclear magnetic resonance T 2 spectrum data and the relative permeability data of core sample, nuclear magnetic resonance T 2 spectrum is turned It is changed to pseudo-relative permeability data, specifically converts according to equation below:

$k_{rw}=\frac{{\∫}_0^{S_i}{\left(T2\right)}^{2}dS}{{\∫}_0^1{\left(T2\right)}^{2}dS}$

$k_{ro}=\frac{{\∫}_{S_i}^1{\left(T2\right)}^{2}dS}{{\∫}_0^1{\left(T2\right)}^{2}dS}$

In formula:

K_rwFor aqueous phase relative permeability, dimensionless,

K_roFor oil relative permeability, dimensionless,

T2 is the T2 that nuclear-magnetism is measured, and unit is ms,

S_iThe percentage ratio of total pore space amount is accounted for for different relaxation time correspondence cumulative porosity amounts；

4) according to step 3) curve corresponding to the pseudo-relative permeability data of gained and the contrast of actual permeability saturation curve, Carry out coefficient C balance correction, reach curve corresponding to described pseudo-relative permeability data with described by balance correction Actual permeability saturation curve is overlapping, completes standardization, and wherein, described coefficient C is that described puppet is permeated relatively The standardization translation coefficient of curve corresponding to rate data and described experiment permeability saturation curve, i.e. the amount of moving left and right；

5) pseudo-permeability saturation curve graphic plotting is carried out.

A kind of method utilizing nuclear magnetic resonance T 2 spectrum to determine reservoir relative permeability the most according to claim 1, its feature It is:

Rock core nuclear-magnetism T2 described in described step (1) tests according to " rock sample nuclear magnetic resonance parameter laboratory measurement specification SY/T6490-2007 " flow process that specifies of standard carries out；

Relative permeability described in described step (1) is tested according to " the mensuration of the biphase permeability saturation curve of rock SY/T5345-2007 " flow process that specifies of standard carries out.