CN104790945A - Method for determining carbonate reservoir saturability - Google Patents

Abstract

The invention relates to a method for determining carbonate reservoir saturability. The method for determining the carbonate reservoir saturability is applied to the determination of heterogeneous carbonate reservoir water saturability. Firstly, a carbonate reservoir saturability capillary tube pressure function is established, standardization is performed on the carbonate reservoir oil-water transition zone electric-log interpretation water phase saturability of each oil well, then polynomial regression is performed with the capillary tube pressure J function, and an iteration method is used to determine the carbonate reservoir saturability. The method for determining the carbonate reservoir saturability has the advantage that a reasonable and reliable calculation method is provided for the calculation of the heterogeneous carbonate reservoir water saturability lack of core data.

Description

A kind of method determining Carbonate Reservoir saturation ratio

Technical field

The present invention relates to oil-gas field development technical field, particularly relate to a kind of method determining Carbonate Reservoir saturation ratio.

Background technology

The key of three-dimensional reservoir Geologic modeling how to determine original water saturation, calculates, the aspect such as the establishment of development plan has great importance to reservoir performance assessment, reserves.When lacking sealing core drilling etc. and directly determining rock core water containing saturability data, accurately ask for a great problem that heterogeneous body carbonate rock reservoir saturation ratio is Log Interpretation always.Because of geological movement change, can there is larger change in RESERVOIR PORE STRUCTURE, the fluid parameter of oil reservoir, the Capillary Pressure Data obtained by mercury injection method can not accurately ask for original water saturation.Meanwhile, asked for carbonate rock reservoir saturation ratio is determine according to Archie formula or derivative formula in the past mostly, and the main impact being subject to resistivity and degree of porosity.But there are many factors to have an impact to resistivity, therefore, utilize the water saturation value of formulae discovery, easily producing larger error of calculation when not considering other influences factor.

Technician, according to the result of calculation of Carbonate Reservoir saturation ratio and oil test data, the comparative analysis of oozing data mutually, finally evaluates the result of log interpretation of Carbonate Reservoir, therefore, accurately asks for Carbonate Reservoir saturation ratio tool and is of great significance.

Summary of the invention

The object of the invention is: a kind of method determining Carbonate Reservoir saturation ratio is provided, set up Carbonate Reservoir capillary pressure force function, standardization is carried out to every mouthful of oil well Carbonate Reservoir water to oil area electric-log interpretation water phase saturation, then polynomial regression is carried out with capillary pressure J function, by iterative method determination Carbonate Reservoir saturation ratio.

The technical scheme that the present invention takes for technical solution problem is:

The first step: the foundation of Carbonate Reservoir capillary pressure J function

$J\left(S_{\mathrm{wn}}\right)=\frac{(H_w-H_{\mathrm{ow}})({\mathrm{\ρ}}_w-{\mathrm{\ρ}}_0)\mathrm{gC}}{\mathrm{\σ}\cos \mathrm{\θ}}\sqrt{\frac{K}{\mathrm{\φ}}+\ln \frac{({\mathrm{\ρ}}_w-{\mathrm{\ρ}}_o)\mathrm{ghc}}{\mathrm{\σ}\cos \mathrm{\θ}}+r_i}......\left(1\right)$

In formula: J (S _wn) be Carbonate Reservoir capillary pressure force function; σ is oil water interfacial tension, N/m; θ is angle of wetting, degree (°); K is Carbonate Reservoir mean permeability, mD; φ is Carbonate Reservoir average pore, f; S _wnfor Carbonate Reservoir rock core standardization water saturation, f; r _ifor the corresponding pore throat radius μm of Carbonate Reservoir rock core; H _wfor the height above sea level degree of depth of aqueous carbonate salt reservoir oil-water interfaces of a certain end, m; H _owfor the degree of depth of any point in aqueous carbonate salt reservoir water to oil area of a certain end, m; H is more than table height, m; ρ _wfor the density of water, kg/m ³; ρ _ofor the density of oil, kg/m ³; G is acceleration of gravity, 9.8m/s ²; S _wnfor Carbonate Reservoir rock core standardization water saturation, f; C is unit conversion coefficient.

Second step: the determination of Carbonate Reservoir rock core standardization water saturation

$S_{\mathrm{wn}}=\frac{S_w-S_{\mathrm{wi}}}{1-S_{\mathrm{or}}-S_{\mathrm{wi}}}...\left(2\right)$

In formula: S _wnfor Carbonate Reservoir rock core standardization water saturation, f; S _wfor Carbonate Reservoir saturation ratio, f; S _wifor irreducible water saturation, f; S _orresidual oil saturation, f.

3rd step: parameter is enrolled

3 ~ 5 mouthfuls of oil wells are chosen in a certain Carbonate Reservoir.

(1) the height above sea level depth H of aqueous carbonate salt reservoir oil-water interfaces of a certain end is calculated _w; The dark H in top of aqueous carbonate salt reservoir oil-water interfaces of a certain end _o; Irreducible water saturation S _wi; Residual oil saturation S _or; H=H _w-H ₀;

Described H _w, H _o, S _wi, S _orcomputational methods be that petroleum industry is known by the technical staff, do not describe in detail at this.

(2) application experiment method obtains σ, θ, ρ _w, ρ _oetc. parameter, its experimental technique is that petroleum industry is known by the technical staff, does not describe in detail at this.

(3) depth H of any point in the known oil well oil-water intermediate zone of a certain end aqueous carbonate salt reservoir _ow, be the degree of depth of actual required point;

The corresponding pore throat radius r of Carbonate Reservoir mean permeability K, Carbonate Reservoir average pore φ, Carbonate Reservoir rock core _i; The data obtained when being drilling well are given data;

(4) C is unit conversion coefficient, and its computational methods petroleum industry is known by the technical staff, does not describe in detail at this.

4th step: the J functional value equation data formula (1) substituted in the first step of the 3rd step admission being obtained any point in Carbonate Reservoir; Utilizing the H of any point in aqueous carbonate salt reservoir water to oil area of a certain end _ow, K, φ, r _icalculate the capillary pressure J function of every a bite oil well oil-water intermediate zone;

5th step: by the irreducible water saturation S of the 3rd step admission _wiwith residual oil saturation S _orformula (2) is utilized to carry out standardization to every mouthful of oil well Carbonate Reservoir water to oil area electric-log interpretation water phase saturation; Then carry out polynomial regression with the capillary pressure J function of every a bite oil well oil-water intermediate zone that calculates in the 4th step, setting up with J is dependent variable, S _wnfor the unary biquadratic equation of independent variable.

$J\left(S_{\mathrm{wn}}\right)={\mathrm{AS}}_{\mathrm{wn}}^4+{\mathrm{BS}}_{\mathrm{wn}}^3+{\mathrm{CS}}_{\mathrm{wn}}^2+\mathrm{DS}+E......\left(3\right)$

6th step: utilize and choose 3 ~ 5 mouthfuls of well informations in a certain Carbonate Reservoir, carries out polynomial regression to formula (3) by least square method method, obtains coefficient A, B, C, D, E in formula (3);

Described least square method method is that petroleum industry is known by the technical staff, does not describe in detail at this.

7th step: by iterative method, formula (3) formula is solved, the water saturation of any point in Carbonate Reservoir can be obtained, namely Carbonate Reservoir saturation ratio.

Beneficial effect of the present invention: the method for determination Carbonate Reservoir saturation ratio of the present invention, set up Carbonate Reservoir capillary pressure force function, standardization is carried out to every mouthful of oil well Carbonate Reservoir water to oil area electric-log interpretation water phase saturation, then polynomial regression is carried out with capillary pressure J function, by iterative method determination Carbonate Reservoir saturation ratio, provide a kind of reasonable, reliable computational methods for lacking asking for of the heterogeneous carbonate reservoir saturation ratio of rock core information.

Detailed description of the invention

Be described in detail with the method for XX basin XX group oil reservoir to determination carbonate reservoir saturation ratio of the present invention.

The first step: the foundation of Carbonate Reservoir capillary pressure J function

$J\left(S_{\mathrm{wn}}\right)=\frac{(H_w-H_{\mathrm{ow}})({\mathrm{\ρ}}_w-{\mathrm{\ρ}}_0)\mathrm{gC}}{\mathrm{\σ}\cos \mathrm{\θ}}\sqrt{\frac{K}{\mathrm{\φ}}+\ln \frac{({\mathrm{\ρ}}_w-{\mathrm{\ρ}}_o)\mathrm{ghc}}{\mathrm{\σ}\cos \mathrm{\θ}}+r_i}......\left(1\right)$

In formula: J (S _wn) be Carbonate Reservoir capillary pressure force function; σ is oil water interfacial tension, N/m; θ is angle of wetting , degree (°); K is Carbonate Reservoir mean permeability, mD; φ is Carbonate Reservoir average pore, f; S _wnfor Carbonate Reservoir rock core standardization water saturation, f; r _ifor the corresponding pore throat radius μm of Carbonate Reservoir rock core; H _wfor the height above sea level degree of depth of aqueous carbonate salt reservoir oil-water interfaces of a certain end, m; H _owfor the degree of depth of any point in aqueous carbonate salt reservoir water to oil area of a certain end, m; H is more than table height, m; ρ _wfor the density of water, kg/m ³; ρ _ofor oil, density kg/m ³; G is acceleration of gravity, 9.8m/s ²; S _wnfor Carbonate Reservoir rock core standardization water saturation, f; C is unit conversion coefficient.

Second step: the determination of Carbonate Reservoir rock core standardization water saturation

$S_{\mathrm{wn}}=\frac{S_w-S_{\mathrm{wi}}}{1-S_{\mathrm{or}}-S_{\mathrm{wi}}}...\left(2\right)$

In formula: S _wnfor Carbonate Reservoir rock core standardization water saturation, f; S _wfor Carbonate Reservoir saturation ratio, f; S _wifor irreducible water saturation, f; S _orresidual oil saturation, f.

3rd step: parameter is enrolled

5 mouthfuls of oil wells are chosen in a certain Carbonate Reservoir.

(1) the height above sea level depth H of aqueous carbonate salt reservoir oil-water interfaces of a certain end is calculated _w; The dark H in top of aqueous carbonate salt reservoir oil-water interfaces of a certain end _o; Irreducible water saturation S _wi; Residual oil saturation S _or; H=H _w-H ₀;

Table 1: calculate in a certain Carbonate Reservoir and choose 5 mouthfuls of oil well basic parameters

Pound sign	S wi(f)	S or(f)	H o(m)	H w(m)	h(m)
						Y1	0.3713	0.2459	2271.6	2287.3	15.7
Y2	0.3583	0.1872	2278.2	2293.1	14.9
						Y3	0.2831	0.2659	2281.4	2292.3	10.9
Y4	0.3518	0.1986	2283.1	2294.8	11.7
						Y5	0.3808	0.1972	2282.7	2293.9	11.2

Described H _w, H _o, S _wi, S _orcomputational methods be that petroleum industry is known by the technical staff, do not describe in detail at this.

(2) application experiment method obtains σ, θ, ρ _w, ρ _oetc. parameter, its experimental technique is that petroleum industry is known by the technical staff, does not describe in detail at this.

Table 2: experiment obtains choosing 5 mouthfuls of oil well basic parameters in a certain Carbonate Reservoir

Pound sign	σ(N/m)	θ(°)	ρ w(kg/m 3)	ρ o(kg/m 3)
					Y1	0.035	30	991.0	718.6
Y2	0.04	120	991.3	718.4
					Y3	0.035	60	991.7	718.1
Y4	0.04	45	992.0	719.2
					Y5	0.04	60	991.6	718.8

(3) depth H of any point in the known oil well oil-water intermediate zone of a certain end aqueous carbonate salt reservoir _ow, the degree of depth of actual required point;

The corresponding pore throat radius r of Carbonate Reservoir mean permeability K, Carbonate Reservoir average pore φ, Carbonate Reservoir rock core _i; The data obtained when being drilling well are given data;

Table 3: choose 5 mouthfuls of oil well basic parameters in a certain Carbonate Reservoir obtained during drilling well

Pound sign	K(mD)	φ(f)	r i(μm)
				Y1	61.5	24.1	56.2
Y2	84.8	28.3	61.9
				Y3	35.1	21.3	36.2
Y4	53.6	26.2	57.3
				Y5	69.5	19.1	61.6

(4) C is unit conversion coefficient is 147.86

4th step: the J functional value equation data formula (1) substituted in the first step of the 3rd step admission being obtained any point in Carbonate Reservoir; Utilizing the H of any point in aqueous carbonate salt reservoir water to oil area of a certain end _ow, K, φ, r _icalculate the capillary pressure J function of every a bite oil well oil-water intermediate zone;

5th step: by the irreducible water saturation S of the 3rd step admission _wiwith residual oil saturation S _orformula (2) is utilized to carry out standardization to every mouthful of oil well Carbonate Reservoir water to oil area electric-log interpretation water phase saturation; Then carry out polynomial regression with the capillary pressure J function of every a bite oil well oil-water intermediate zone that calculates in the 4th step, setting up with J is dependent variable, S _wnfor the unary biquadratic equation of independent variable.

$J\left(S_{\mathrm{wn}}\right)={\mathrm{AS}}_{\mathrm{wn}}^4+{\mathrm{BS}}_{\mathrm{wn}}^3+{\mathrm{CS}}_{\mathrm{wn}}^2+\mathrm{DS}+E......\left(3\right)$

6th step: utilize and choose 3 ~ 5 mouthfuls of well informations in a certain Carbonate Reservoir, carries out polynomial regression to formula (3) by least square method method, obtains the coefficient in formula (3)

A＝-0.763，B＝-0.567，C＝3.461；D＝-3.646，E＝1.5012

Described least square method method is that petroleum industry is known by the technical staff, does not describe in detail at this.

7th step: by iterative method, formula (3) formula is solved, the water saturation of any point in Carbonate Reservoir can be obtained, namely Carbonate Reservoir saturation ratio.

Table 4: choose any saturation ratio of 5 mouthfuls of oil wells in a certain Carbonate Reservoir

Pound sign	H ow(m)	S w(f)
			Y1	2279.3	0.3719
Y2	2284.1	02931
			Y3	2287.5	0.4207
Y4	2289.3	0.3901
			Y5	2284.4	0.2065

The method for expressing adopted in this manual, be those skilled in the art's usages, those skilled in the art know, and are not explained in more detail.

As mentioned above, embodiments of the invention are explained, but as long as do not depart from inventive point of the present invention in fact and effect can have a lot of distortion, this will be readily apparent to persons skilled in the art.Therefore, such variation is also all included within protection scope of the present invention.

Claims (5)

1. determine a method for Carbonate Reservoir saturation ratio, it is characterized in that:

The first step: the foundation of Carbonate Reservoir capillary pressure J function

$J\left(S_{\mathrm{wn}}\right)=\frac{(H_w-H_{\mathrm{ow}})({\mathrm{\ρ}}_w-{\mathrm{\ρ}}_0)\mathrm{gC}}{\mathrm{\σ}\cos \mathrm{\θ}}\sqrt{\frac{K}{\mathrm{\φ}}+\ln \frac{({\mathrm{\ρ}}_w-{\mathrm{\ρ}}_o)\mathrm{ghc}}{\mathrm{\σ}\cos \mathrm{\θ}}+r_i}......\left(1\right)$

(1) in formula: J (S _wn) be Carbonate Reservoir capillary pressure force function; σ is oil water interfacial tension, N/m; θ is angle of wetting, degree (°); K is Carbonate Reservoir mean permeability, mD; φ is Carbonate Reservoir average pore, f; S _wnfor Carbonate Reservoir rock core standardization water saturation, f; r _ifor the corresponding pore throat radius μm of Carbonate Reservoir rock core; H _wfor the height above sea level degree of depth of aqueous carbonate salt reservoir oil-water interfaces of a certain end, m; H _owfor the degree of depth of any point in aqueous carbonate salt reservoir water to oil area of a certain end, m; H is more than table height, m; ρ _wfor the density of water, kg/m ³; ρ _ofor the density of oil, kg/m ³; G is acceleration of gravity, 9.8m/s ²; S _wnfor Carbonate Reservoir rock core standardization water saturation, f; C is unit conversion coefficient;

Second step: the determination of Carbonate Reservoir rock core standardization water saturation

$S_{\mathrm{wn}}=\frac{S_w-S_{\mathrm{wi}}}{1-S_{\mathrm{or}}-S_{\mathrm{wi}}}...\left(2\right)$

(2) in formula: S _wnfor Carbonate Reservoir rock core standardization water saturation, f; S _wfor Carbonate Reservoir saturation ratio, f; S _wifor irreducible water saturation, f; S _orresidual oil saturation, f;

3rd step: parameter is enrolled

3 ~ 5 mouthfuls of oil wells are chosen in a certain Carbonate Reservoir;

Further: the height above sea level depth H calculating aqueous carbonate salt reservoir oil-water interfaces of a certain end _w; The dark H in top of aqueous carbonate salt reservoir oil-water interfaces of a certain end _o; Irreducible water saturation S _wi; Residual oil saturation S _or: h=H _w-H ₀;

Further: application experiment method obtains σ, θ, ρ _w, ρ _oetc. parameter;

Further: the depth H of any point in the known oil well oil-water intermediate zone of a certain end aqueous carbonate salt reservoir _ow(degree of depth of actual required point);

The corresponding pore throat radius r of Carbonate Reservoir mean permeability K, Carbonate Reservoir average pore φ, Carbonate Reservoir rock core _i; The data obtained when being drilling well are given data;

4th step: the J functional value equation data formula (1) substituted in the first step of the 3rd step admission being obtained any point in Carbonate Reservoir; Utilizing the H of any point in aqueous carbonate salt reservoir water to oil area of a certain end _ow, K, φ, r _icalculate the capillary pressure J function of every a bite oil well oil-water intermediate zone;

5th step: by the irreducible water saturation S of the 3rd step admission _wiwith residual oil saturation S _orformula (2) is utilized to carry out standardization to every mouthful of oil well Carbonate Reservoir water to oil area electric-log interpretation water phase saturation; Then carry out polynomial regression with the capillary pressure J function of every a bite oil well oil-water intermediate zone that calculates in the 4th step, setting up with J is dependent variable, S _wnfor the unary biquadratic equation of independent variable;

$J\left(S_{\mathrm{wn}}\right)={\mathrm{AS}}_{\mathrm{wn}}^4+{\mathrm{BS}}_{\mathrm{wn}}^3+{\mathrm{CS}}_{\mathrm{wn}}^2+\mathrm{DS}+E.....\left(3\right)$

6th step: utilize and choose 3 ~ 5 mouthfuls of well informations in a certain Carbonate Reservoir, carries out polynomial regression to formula (3) by least square method method, obtains coefficient A, B, C, D, E in formula (3);

Described least square method method is that petroleum industry is known by the technical staff, does not describe in detail at this.

7th step: by iterative method, formula (3) formula is solved, the water saturation of any point in Carbonate Reservoir can be obtained, namely Carbonate Reservoir saturation ratio.

2. H as claimed in claim 1 _w, H _o, S _wi, S _orcomputational methods be that petroleum industry is known by the technical staff.

3. application experiment method as claimed in claim 1 obtains σ, θ, ρ _w, ρ _oetc. parameter, its experimental technique is that petroleum industry is known by the technical staff.

4. C as claimed in claim 1 is unit conversion coefficient, and its computational methods are that petroleum industry is known by the technical staff.

5. least square method method as claimed in claim 1 carries out that multinomial and iterative method return is conventional mathematical method, is that petroleum industry is known by the technical staff.