CN103439748A - Method for detecting stratum, method for calculating oil and gas saturation of stratum, combination electrode and detector - Google Patents

Abstract

The embodiment of the invention discloses a method for detecting a stratum, a method for calculating oil and gas saturation of the stratum, a combination electrode and a detector. The method for detecting the stratum includes the steps that measuring signals are transmitted to a target stratum; vector electric potentials and vector currents of reflected signals obtained through the transmitted measuring signals via reflection of the target stratum are measured; first complex resistivity of the target stratum is obtained according to the vector electric potentials and vector currents of the reflected signals; the initial value of an SW is set, and second complex resistivity is obtained by means of a formula; when the difference between the first complex resistivity and the second complex resistivity is less than or equal to a predetermined value, the current SW value is determined as the SW value of the target stratum; when the difference between the first complex resistivity and the second complex resistivity is greater than the predetermined value, the SW value is adjusted according to a predetermined step length until the difference between the first complex resistivity and the second complex resistivity is less than or equal to the predetermined value, and at the moment, the SW value is determined as the SW value of the target stratum; the oil and gas saturation value of the target stratum is obtained according to the determined SW value of the target stratum. Accordingly, the result can be more accurate.

Description

Survey the method on stratum, method and combination electrode and the detector of calculating stratum hydrocarbon saturation

Technical field

The present invention relates to the seismic exploration technical field, particularly a kind of method on stratum, method and combination electrode and detector of calculating stratum hydrocarbon saturation surveyed.

Background technology

In seismic exploration, in order to determine whether the stratum of exploring has oil-gas mining and be worth, and generally will this parameter of hydrocarbon saturation based on this stratum determine.In order to obtain this parameter, need to by a series of measurement, calculate the reflection virgin zone other parameter.Carry out the hydrocarbon saturation of evaluation of earth formations by these other parameters that obtain, and then the concrete mining type of planning and employing etc. is exploited, exploited to decision whether.

Prior art adopts single scalar parameter, and then the hydrocarbon saturation of evaluation of earth formations.This single scalar parameter is for example real part resistivity or conductivity, or the real part specific inductive capacity.Because this resistivity or conductivity parameter are affected greatly by the local water salt-containing amount mineralization degree, be difficult for obtaining the exact value of resistivity or conductivity parameter, therefore utilize this resistivity or conductivity parameter to determine that the hydrocarbon saturation that approaches truth has difficulties.

Summary of the invention

One object of the present invention is to provide a kind of method on stratum, method and combination electrode and detector of calculating stratum hydrocarbon saturation surveyed, to obtain hydrocarbon saturation comparatively accurately.

For achieving the above object, the scheme that the present invention adopts is as follows:

A kind of method of surveying stratum comprises:

S1: to formation at target locations emission measurement signal;

S2: the measuring-signal of measuring described emission reflects vector current potential and the vector current of the reflected signal obtained through described formation at target locations;

S3: the first complex resistivity that obtains formation at target locations according to vector current potential and the vector current of described reflected signal;

S4: set a water saturation S _winitial value, utilize following formula to obtain the second complex resistivity:

${{\mathrm{\ρ}}^{*}}_2\left(\mathrm{\ω}\right)=\frac{\mathrm{ab}{R}_W}{{\mathrm{\φ}}^m{S}_W^n}[1-{\mathrm{\η}}_1(1-\frac{1}{1+{\left(\mathrm{j\ω}{\mathrm{\τ}}_1\right)}^{c_1}})]\×[1-{\mathrm{\η}}_2(1-\frac{1}{1+{\left(\mathrm{j\ω}{\mathrm{\τ}}_2\right)}^{c_2}})]$

In above formula, ρ ^* ₂(ω) be the second complex resistivity, the angular frequency that ω is electric field, j is imaginary unit; τ is relaxation time; η is polarizability; C is frequency correlation coefficient; R _wit is formation water resistivity; φ is formation porosity; A, b are coefficient; M, n are provisional index;

S5: when the difference of the first complex resistivity and the second complex resistivity is less than or equal to predetermined value, determine current S _wvalue is the water saturation value of formation at target locations; When the difference of the first complex resistivity and the second complex resistivity is greater than predetermined value, to be scheduled to step-length, adjust S _wvalue, until the difference of the first complex resistivity and the second complex resistivity is while being less than or equal to predetermined value, definite S now _wvalue is the water saturation value of formation at target locations;

S6: the hydrocarbon saturation value that obtains formation at target locations according to the water saturation value of definite formation at target locations.

Described measuring-signal can comprise single-frequency and/or multifrequency signal;

The signal of described single-frequency can comprise low frequency and/or high-frequency signal;

Described multifrequency signal can comprise multifrequency low frequency signal, or multifrequency high-frequency signal, or has the multifrequency signal of low frequency signal and high-frequency signal concurrently.

Can adopt inductolog or electromagnetic wave logging mode to receive described reflected signal.

Described predetermined step-length can be fixed value, can be also a series of different value.

A kind of method of calculating the stratum hydrocarbon saturation comprises:

S1: obtain vector current potential and the vector current of reflected signal, obtain the first complex resistivity of formation at target locations;

S2: set water saturation S _winitial value, utilize following formula to obtain the second complex resistivity:

${{\mathrm{\ρ}}^{*}}_2\left(\mathrm{\ω}\right)=\frac{\mathrm{ab}{R}_W}{{\mathrm{\φ}}^m{S}_W^n}[1-{\mathrm{\η}}_1(1-\frac{1}{1+{\left(\mathrm{j\ω}{\mathrm{\τ}}_1\right)}^{c_1}})]\×[1-{\mathrm{\η}}_2(1-\frac{1}{1+{\left(\mathrm{j\ω}{\mathrm{\τ}}_2\right)}^{c_2}})]$

In above formula, ρ ^* ₂(ω) be the second complex resistivity, the angular frequency that ω is electric field, j is imaginary unit; τ is relaxation time; η is polarizability; C is frequency correlation coefficient; R _wit is formation water resistivity; φ is formation porosity; A, b are coefficient; M, n are provisional index;

S3: when the difference of the first complex resistivity and the second complex resistivity is less than or equal to predetermined value, determine current S _wvalue is the water saturation value of formation at target locations; When the difference of the first complex resistivity and the second complex resistivity is greater than predetermined value, to be scheduled to step-length, adjust S _wvalue, until the difference of the first complex resistivity and the second complex resistivity is while being less than or equal to predetermined value, definite S now _wvalue is the water saturation value of formation at target locations;

S4: the hydrocarbon saturation value that obtains formation at target locations according to the water saturation value of definite formation at target locations.

A kind of combination electrode that is applied to said method, this combination electrode comprises the composite structure of electrode and coil.

It is non-closing structure that the electrode part of combination electrode divides the cylinder in the outside, the axle in the axle center that center is penetrating electrode place cylinder; This axle is cylindricality, and the diameter of this columnar shaft xsect is less than the diameter of the xsect of cylinder place cylindricality; Each independent face of the non-closed cylinder in the described electrode outside is connected with described axle by connecting rod.

Described electrode and coil are crisscross arranged.

A kind of detector, comprise combination electrode as above.

By the invention described above embodiment of the method, introduced a plurality of parameters in obtaining the hydrocarbon saturation process, and adopted the comprehensive evaluation mode.The evaluation method of the information reflected with respect to single parameter, estimate by the information of a plurality of parameters reflections, can offset the inaccurate impact that result is brought of indivedual parameters, therefore can make result more accurate.

By the embodiment of the invention described above combination electrode and detector, can measure the signal under different frequency, can also measure low frequency and high-frequency signal simultaneously, can cover wider frequency range requirement.

The accompanying drawing explanation

Fig. 1 is the process flow diagram that the present invention surveys the embodiment of the method on stratum;

Fig. 2 is that the variation relation of rear real part resistivity with frequency and water saturation proofreaied and correct in electrode polarization of the present invention;

Fig. 3 is that the variation relation of rear imaginary part resistivity with frequency and water saturation proofreaied and correct in electrode polarization of the present invention;

Fig. 4 is that the variation relation of rear conductivity with frequency and water saturation proofreaied and correct in electrode polarization of the present invention;

Fig. 5 is that the variation relation of rear specific inductive capacity with frequency and water saturation proofreaied and correct in electrode polarization of the present invention;

Fig. 6 is the process flow diagram that the present invention calculates the embodiment of the method for stratum hydrocarbon saturation;

Fig. 7 is the structural drawing of prior art electrode;

Fig. 8 is the structural representation of combination electrode embodiment of the present invention;

Fig. 9 is the structural drawing of an embodiment of combination electrode of the present invention;

Figure 10 is the structural drawing of an embodiment of combination electrode of the present invention.

Embodiment

In order to make those skilled in the art person understand better the present invention program, below in conjunction with the accompanying drawing in the embodiment of the present invention, technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only the present invention's part embodiment, rather than whole embodiment.Embodiment based in the present invention, those of ordinary skills, not making under the creative work prerequisite the every other embodiment obtained, should belong to the scope of protection of the invention.

In geological engineering, water saturation and the hydrocarbon saturation on stratum are corresponding relation.When water saturation and hydrocarbon saturation mean with the number percent form, both corresponding relations are as follows:

Hydrocarbon saturation=1-water saturation

First obtain often water saturation in the middle of practice, draw hydrocarbon saturation according to above formula more afterwards.Below with S _wmean water saturation, hydrocarbon saturation is 1-S _w.

Utilize in the process of hydrocarbon saturation on measurement mechanism measurement target stratum, at first adopt measurement mechanism, by the electrode of this measurement mechanism, launch the measuring-signal of a certain frequency or certain several frequency to formation at target locations.The signal of launching, through described formation at target locations, is subject to the impact on passed stratum, the variation of signal generation amplitude and phase place etc.When these signals reflex to described measurement mechanism again, voltage vector parameter and current phasor parameter that these signals are corresponding are measured by described measurement mechanism.Corresponding voltage vector parameter and the current phasor parameter according to the described signal measured, further obtain complex resistivity or the conductivity of described formation at target locations.And then, according to described complex resistivity (or conductivity) and specific inductive capacity and the isoparametric corresponding relation of Dispersion, draw the oil gas situation of described formation at target locations.

Wherein, complex resistivity and conductivity mean as shown in the formula (1), (2) respectively:

Conductivity: σ ^*(ω)=[σ ' (ω)+ω ε "]+j[σ " (ω)+ω ε '] (1)

Complex resistivity:

${\mathrm{\ρ}}^{*}\left(\mathrm{\ω}\right)=\frac{1}{{\mathrm{\σ}}^{*}\left(\mathrm{\ω}\right)}=\frac{{\mathrm{\σ}}^{\′}\left(\mathrm{\ω}\right)+{\mathrm{\ω\ϵ}}^{\′\′}}{{({\mathrm{\σ}}^{\′}\left(\mathrm{\ω}\right)+{\mathrm{\ω\ϵ}}^{\′\′})}^2+{({\mathrm{\σ}}^{\′\′}\left(\mathrm{\ω}\right)+{\mathrm{\ω\ϵ}}^{\′})}^2}$ (2)

$-j\frac{{\mathrm{\σ}}^{\′\′}\left(\mathrm{\ω}\right)+{\mathrm{\ω\ϵ}}^{\′}}{{({\mathrm{\σ}}^{\′}\left(\mathrm{\ω}\right)+{\mathrm{\ω\ϵ}}^{\′\′})}^2+{({\mathrm{\σ}}^{\′\′}\left(\mathrm{\ω}\right)+{\mathrm{\ω\ϵ}}^{\′})}^2}$

Meaning as shown in the formula (3) of complex permittivity:

Complex permittivity: ${\mathrm{\ϵ}}^{*}\left(\mathrm{\ω}\right)=[{\mathrm{\ϵ}}^{\′}\left(\mathrm{\ω}\right)+\frac{{\mathrm{\σ}}^{\′\′}}{\mathrm{\ω}}]+j[{\mathrm{\ϵ}}^{\′\′}\left(\mathrm{\ω}\right)-\frac{{\mathrm{\σ}}^{\′}}{\mathrm{\ω}}]---\left(3\right)$

In the actual measurement process, can adopt rock multifrequency electricity physical model, this model can be expressed as with formula (4):

${\mathrm{\ρ}}^{*}\left(\mathrm{\ω}\right)={\mathrm{\ρ}}_0[1-{\mathrm{\η}}_1(1-\frac{1}{1+{\left(\mathrm{j\ω}{\mathrm{\τ}}_1\right)}^{c_1}})]\×[1-{\mathrm{\η}}_2(1-\frac{1}{1+{\left(\mathrm{j\ω}{\mathrm{\τ}}_2\right)}^{c_2}})]---\left(4\right)$

In top formula (1)-(4), with asterisk * sign plural number; Subscript ' and " represent respectively real part and imaginary part; ρ ^*(ω) be the complex resistivity of formation at target locations; The angular frequency that ω is electric field; ε is specific inductive capacity; τ is relaxation time; J is imaginary unit; η is polarizability, and it is worth between 0 and 1; C is frequency correlation coefficient, and it is worth also between 0 and 1.

ρ ₀complex resistivity amplitude during for zero frequency can be expressed as follows with formula (5):

${\mathrm{\ρ}}_0=\frac{\mathrm{ab}{R}_W}{{\mathrm{\φ}}^m{S}_W^n}---\left(5\right)$

In formula (5), R _wbe formation water resistivity, φ is formation porosity.

In formula (4) and (5), η ₁, η ₂, c ₁, c ₂, τ ₁, τ ₂, a, b, m, n, φ, these parameters of Rw solving in follow-up introduction in embodiments of the present invention.Sw is most important amount to be asked.Wherein, τ ₁, τ ₂be respectively the first relaxation time, the second relaxation time; η ₁, η ₂be respectively the first polarizability and the first polarizability; c ₁, c ₂be respectively first frequency related coefficient and second frequency related coefficient.τ ₁, τ ₂, η ₁, η ₂, c ₁, c ₂for the parameter relevant with water saturation.

By formula (5) substitution formula (4), obtain following formula (6):

${\mathrm{\ρ}}^{*}\left(\mathrm{\ω}\right)=\frac{\mathrm{ab}{R}_W}{{\mathrm{\φ}}^m{S}_W^n}[1-{\mathrm{\η}}_1(1-\frac{1}{1+{\left(\mathrm{j\ω}{\mathrm{\τ}}_1\right)}^{c_1}})]\×[1-{\mathrm{\η}}_2(1-\frac{1}{1+{\left(\mathrm{j\ω}{\mathrm{\τ}}_2\right)}^{c_2}})]---\left(6\right)$

Formula (6) right-hand member except φ, Rw and angular frequency known, remaining is amount to be asked; And the directly measured quantities of left end Xiang Zewei the method.

In order to determine 11 unknown numbers of formula (6) right-hand member, the system of equations that at least needs 11 equations to form could be determined.Because above formula is complex number equation, its 1 equation comprises 2 real number equations, thereby at least must have the complex resistivity of 6 different Frequency points to measure the Sw parameter that (i.e. 6 complex number equations) just can obtain the equation right-hand member.And, for multifrequency measurement, consider to cover frequency corresponding to complex resistivity imaginary part curve the lowest point and the susceptibility of water saturation, should allow these frequencies cover as much as possible it, this is the needs of being avoided the inverting multi-solution as far as possible.

The frequency of supposing employing is ω ₁, ω ₂..., ω _n, measure respectively ρ ^*(ω ₁), ρ ^*(ω ₂) ..., ρ ^*(ω _n) this N value, by formula (6), can be obtained:

$\left\{\begin{array}{c}{\mathrm{\ρ}}^{*}\left({\mathrm{\ω}}_1\right)=\frac{\mathrm{ab}{R}_W}{{\mathrm{\φ}}^m{S}_W^n}[1-{\mathrm{\η}}_1(1-\frac{1}{1+{\left(j{\mathrm{\ω}}_1{\mathrm{\τ}}_1\right)}^{c_1}})]\×[1-{\mathrm{\η}}_2(1-\frac{1}{1+{\left(j{\mathrm{\ω}}_1{\mathrm{\τ}}_2\right)}^{c_2}})]\\ {\mathrm{\ρ}}^{*}\left({\mathrm{\ω}}_2\right)=\frac{\mathrm{ab}{R}_W}{{\mathrm{\φ}}^m{S}_W^n}[1-{\mathrm{\η}}_1(1-\frac{1}{1+{\left(j{\mathrm{\ω}}_2{\mathrm{\τ}}_1\right)}^{c_1}})]\×[1-{\mathrm{\η}}_2(1-\frac{1}{1+{\left(j{\mathrm{\ω}}_2{\mathrm{\τ}}_2\right)}^{c_2}})]\\ .\\ .\\ .\\ {\mathrm{\ρ}}^{*}\left({\mathrm{\ω}}_N\right)=\frac{\mathrm{ab}{R}_W}{{\mathrm{\φ}}^m{S}_W^n}[1-{\mathrm{\η}}_1(1-\frac{1}{1+{\left(j{\mathrm{\ω}}_N{\mathrm{\τ}}_1\right)}^{c_1}})]\×[1-{\mathrm{\η}}_2(1-\frac{1}{1+{\left(j{\mathrm{\ω}}_N{\mathrm{\τ}}_2\right)}^{c_2}})]\end{array}\right.---\left(7\right)$

For system of equations (7), when its corresponding real number equation number is no less than wait the amount of asking number, do not need the help of rock core Physical Experiment information just can adopt least square method directly to obtain S _w.

Adopt the least square method method for solving as follows:

At first construct an objective function

for system of equations (7) is set up, Q should obtain minimal value.According to the theory of minimizing on mathematics, need to find one group of coefficient (S _w, η ₁, τ ₁, c ₁, η ₂, τ ₂, c ₂) make Q reach minimum:

$\left\{\begin{array}{c}\frac{\&PartialD;Q}{\&PartialD;S_w}=\frac{\&PartialD;\underset{k=1}{\overset{N}{\mathrm{\&Sigma;}}}{[{\mathrm{\&rho;}}_1^{*}-{\mathrm{\&rho;}}_2^{*}\left({\mathrm{\&omega;}}_k\right)]}^2}{\&PartialD;S_w}=0\\ \frac{\&PartialD;Q}{\&PartialD;{\mathrm{\&eta;}}_1}=\frac{\&PartialD;\underset{k=1}{\overset{N}{\mathrm{\&Sigma;}}}{[{\mathrm{\&rho;}}_1^{*}\left({\mathrm{\&omega;}}_k\right)-{\mathrm{\&rho;}}_2^{*}\left({\mathrm{\&omega;}}_k\right)]}^2}{\&PartialD;{\mathrm{\&eta;}}_1}=0\\ .\\ .\\ .\\ \frac{\&PartialD;Q}{\&PartialD;{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="HDA0000371984480000052.png"\; state="\{\{state\}\}">c</figure-callout>}}_2}=\frac{\&PartialD;\underset{k=1}{\overset{N}{\mathrm{\&Sigma;}}}{[{\mathrm{\&rho;}}_1^{*}\left({\mathrm{\&omega;}}_k\right)-{\mathrm{\&rho;}}_2^{*}\left({\mathrm{\&omega;}}_k\right)]}^2}{\&PartialD;{\mathrm{<figure-callout\; id="2"\; label="c"\; filenames="HDA0000371984480000052.png"\; state="\{\{state\}\}">c</figure-callout>}}_2}=0\end{array}\right.---\left(8\right)$

Like this, by minimizing calculating on mathematics, can try to achieve S by least square method _w.

In addition, when the undetermined coefficient of system of equations (8) equates with the equation number, also can solve and obtain by common solving equations method.

Equation number in system of equations (7) is less than when the amount of asking number, needs could determine S by the help of rock core Physical Experiment _w.By the intervention of core experiment, can obtain more information.Like this, be equivalent to, in the situation that the well site, stratum is inadequate by directly measuring the equation quantity obtained, on-the-spot rock core be measured in laboratory, set up more equation.The supplementary equation by core experiment, make the equation total quantity reach requirement, thereby can make system of equations solve.

Below introduce the embodiment that measures stratum hydrocarbon saturation method in the situation that the present invention introduces core experiment.Fig. 1 shows the flow process of this embodiment, and as shown in Figure 1, this embodiment comprises:

S110: to formation at target locations emission measurement signal.

Described measuring-signal can be specifically the signal of single-frequency, as can low frequency signal, can be also high-frequency signal.In addition, can also be multifrequency signal, can be multifrequency low frequency signal, can be also multifrequency high-frequency signal, can also be the multifrequency signal that has low frequency signal and high-frequency signal concurrently.

S120: the measuring-signal of measuring described emission reflects vector current potential and the vector current of the reflected signal obtained through described formation at target locations.

As previously mentioned, the signal of launching, through described formation at target locations, is subject to the impact on passed stratum, the variation of signal generation amplitude and phase place etc.When these signals reflex to described measurement mechanism again, voltage vector parameter and current phasor parameter that these signals are corresponding are measured by described measurement mechanism.

The subject of implementation of S110 and S120 can be measurement mechanism.

When frequency is greater than 500kHz, measurement mechanism can adopt the measurement of electromagnetic wave logging mode to be measured.While adopting the electromagnetic wave logging mode to measure, will adopt the coil on detector to be transmitted and received signal, pass to the mode emitting electromagnetic wave of exchange current toward transmitting coil during measurement, when this electromagnetic wave is propagated in stratum, its amplitude and phase place are affected by the stratum electrology characteristic to change.Utilize two receiving coils from the transmitting coil different distance to receive this electromagnetic wave signal, measure Amplitude Ratio and phase differential that this electromagnetic wave arrives these two receiving coils, and then calculate conductivity and the specific inductive capacity on stratum, finally converting the complex resistivity on stratum to according to aforementioned formula (2).

S130: obtain vector current potential and the vector current of described reflected signal from measurement mechanism, thereby obtain the first complex resistivity of formation at target locations.

If described vector current potential is U, vector current is I, described measurement complex resistivity ρ ^* ₁(ω)=k (U/I), wherein k is the instrument coefficient, by instrument itself, determined, be known fixed.

S140: set a water saturation S _winitial value, utilize following formula to obtain the second complex resistivity:

${{\mathrm{\&rho;}}^{*}}_2\left(\mathrm{\&omega;}\right)=\frac{\mathrm{ab}{R}_W}{{\mathrm{\&phi;}}^m{S}_W^n}[1-{\mathrm{\&eta;}}_1(1-\frac{1}{1+{\left(\mathrm{j\&omega;}{\mathrm{\&tau;}}_1\right)}^{c_1}})]\&times;[1-{\mathrm{\&eta;}}_2(1-\frac{1}{1+{\left(\mathrm{j\&omega;}{\mathrm{\&tau;}}_2\right)}^{c_2}})]---\left(9\right)$

Wherein, the angular frequency that ω is electric field, j is imaginary unit; ρ ^* ₂(ω) be the second complex resistivity;

In addition, τ is relaxation time; η is polarizability; C is frequency correlation coefficient; R _wit is formation water resistivity; φ is formation porosity; A, b are coefficient; M, n are provisional index.

The electric field angular frequency, relaxation time τ, polarizability η, frequency correlation coefficient c, formation water resistivity R _w, formation porosity φ, coefficient a, b, these parameters of provisional index m, n are set as known quantity in this application, for example by alternate manner, obtain.Specifically how to solve, can utilize multitude of different ways of the prior art to obtain.Follow-uply will enumerate a kind of mode that specifically solves.

The step main body of step S130 and S140 can be calculation element.

It should be noted that, calculation element is set water saturation S _winitial value, also can complete in the step before S140.

S150: when the difference of the first complex resistivity and the second complex resistivity is less than or equal to predetermined value, determine current S _wvalue is the water saturation value of formation at target locations; When the difference of the first complex resistivity and the second complex resistivity is greater than predetermined value, to be scheduled to step-length, adjust S _wvalue, until the difference of the first complex resistivity and the second complex resistivity is while being less than or equal to predetermined value, definite S now _wvalue is the water saturation value of formation at target locations.

Wherein, predetermined value is predefined value, and its assignment procedure can be considered the situation on stratum, and the requirement of accuracy rating etc. is set.

Wherein, predetermined step-length can be fixed value, can be a series of different value.The latter for example can be set with an algorithm, and the adjustment of passing through step-length that is makes the difference of the first complex resistivity and the second complex resistivity be less than or equal as far as possible the result of predetermined value by the adjustment of less number of times.

S160: the hydrocarbon saturation value that obtains formation at target locations according to the water saturation value of definite formation at target locations.

As previously mentioned, obtaining the water saturation value S of formation at target locations _wafterwards, can obtain hydrocarbon saturation (1-S _w).

It should be noted that, preferably adopt from the electric signal of a plurality of different frequencies of 10Hz～10MHz scope and carry out transmitting and receiving step S110 and S120.

Relaxation time τ, polarizability η, frequency correlation coefficient c, formation water resistivity R _w, formation porosity φ, coefficient a, b, the solving of provisional index m, these parameters of n, below simply introduce a kind of mode of least square method, and this mode belongs to existing usual way.By the rock core complex resistivity under the laboratory measurement different frequency, set up the system of equations of equation number much larger than amount number to be asked, then by least square method, solve and obtain above each parameter.Because rock core is that fetch at scene, thereby it is representing on-the-spot situation.Therefore, the value of each parameter of determining by least square method, go in the aforementioned embodiment of the present invention determining the oil saturation value.Determined that the equation (8) after these coefficients is called with the calibrated model of rock core.

Measurement result in Fig. 2, Fig. 3 is carried out to traditional rock electricity Data Processing in Experiment (SW1=0.96 in Fig. 2 and Fig. 3, SW2=0.897, SW3=0.799, SW4=0.718, SW5=0.517), take out conventional (scalar resistivity) saturation degree evaluation model, result is illustrated in fig. 4 shown below, and meets Archie equation (to be

the formula of traditional evaluation water saturation) rule, thereby these core test data are correct.Crest frequency and water saturation to the imaginary part resistivity of this rock core are mapped, obtain Fig. 5 relation, can find out that imaginary part resistivity crest frequency and rock core water containing saturability have good regular corresponding relation, and imaginary part resistivity crest frequency is corresponding to the relaxation time τ of multifrequency electricity physical model, therefore, relaxation time τ is suitable for estimating the water saturation (or hydrocarbon saturation) of rock.

In the above embodiment of the present invention, in obtaining the hydrocarbon saturation process, introduce a plurality of parameters, and adopted the comprehensive evaluation mode.The evaluation method of the information reflected with respect to single parameter, it is more accurate by the information of a plurality of parameters reflections, to estimate, and this meets information-theoretical ultimate principle.

Below introduce the embodiment that the present invention calculates stratum hydrocarbon saturation method.Fig. 6 shows the flow process of this embodiment, and as shown in Figure 6, this embodiment comprises:

S210: obtain vector current potential and the vector current of reflected signal, obtain the first complex resistivity of formation at target locations.

If described vector current potential is U, vector current is I, described measurement complex resistivity ρ ^* ₁(ω)=k (U/I), wherein k is the instrument coefficient, by instrument itself, determined, be known fixed.

S220: set water saturation S _winitial value, utilize following formula to obtain the second complex resistivity:

${{\mathrm{\&rho;}}^{*}}_2\left(\mathrm{\&omega;}\right)=\frac{\mathrm{ab}{R}_W}{{\mathrm{\&phi;}}^m{S}_W^n}[1-{\mathrm{\&eta;}}_1(1-\frac{1}{1+{\left(\mathrm{j\&omega;}{\mathrm{\&tau;}}_1\right)}^{c_1}})]\&times;[1-{\mathrm{\&eta;}}_2(1-\frac{1}{1+{\left(\mathrm{j\&omega;}{\mathrm{\&tau;}}_2\right)}^{c_2}})]---\left(9\right)$

In above formula, ρ ^* ₂(ω) be the second complex resistivity, the angular frequency that ω is electric field, j is imaginary unit; τ is relaxation time; η is polarizability; C is frequency correlation coefficient; R _wit is formation water resistivity; φ is formation porosity; A, b are coefficient; M, n are provisional index;

The electric field angular frequency, relaxation time τ, polarizability η, frequency correlation coefficient c, formation water resistivity R _w, formation porosity φ, coefficient a, b, these parameters of provisional index m, n are set as known quantity in this application, for example by alternate manner, obtain.Specifically how to solve, can utilize multitude of different ways of the prior art to obtain.

S230: when the difference of the first complex resistivity and the second complex resistivity is less than or equal to predetermined value, determine current S _wvalue is the water saturation value of formation at target locations; When the difference of the first complex resistivity and the second complex resistivity is greater than predetermined value, to be scheduled to step-length, adjust S _wvalue, until the difference of the first complex resistivity and the second complex resistivity is while being less than or equal to predetermined value, definite S now _wvalue is the water saturation value of formation at target locations.

Wherein, predetermined value is predefined value, and its assignment procedure can be considered the situation on stratum, and the requirement of accuracy rating etc. is set.

Wherein, predetermined step-length can be fixed value, can be a series of different value.The latter for example can be set with an algorithm, and the adjustment of passing through step-length that is makes the difference of the first complex resistivity and the second complex resistivity be less than or equal as far as possible the result of predetermined value by the adjustment of less number of times.

S240: the hydrocarbon saturation value that obtains formation at target locations according to the water saturation value of definite formation at target locations.

As previously mentioned, obtaining the water saturation value S of formation at target locations _wafterwards, can obtain hydrocarbon saturation (1-S _w).

As previously mentioned, relaxation time τ, polarizability η, frequency correlation coefficient c, formation water resistivity R _w, formation porosity φ, coefficient a, b, solving of provisional index m, these parameters of n, can adopt the mode of prior art to obtain, and for example the mode by least square method obtains.

Below introduce in the present invention the combination electrode embodiment that is applied to said method.

The available technology adopting single-frequency is measured single scalar parameter, employing be the structure of unitary electrode or single coil.In the unitary electrode structure, electrode is cylindrical tube shape, and electrode is closed at the circumferencial direction of cylinder, as shown in Figure 7.In single loop construction, the glass-reinforced plastic material of the general full employing insulation of its plug.

The requirement of a most preferred embodiment of aforementioned detection method according to the present invention, detector preferably can provide transmitting and receiving of the electric signal of frequency from 10Hz～10MHz scope, and the embodiment of the present invention also provides a kind of combination electrode.Available technology adopting unitary electrode or coil all can not meet the requirement of frequency range, thereby have taked in embodiments of the present invention the combination of electrode and coil, i.e. combination electrode, and for example as shown in Figure 8, A is coil, B is electrode.Wherein low frequency signal adopts electrode measurement, and high-frequency signal adopts coil to measure.Low frequency adopts electrode effective, and the frequency height will adopt coil, because electrode does not provide radiation of power.For the electrode system of low-frequency range, can be typically to adopt array electrode to add the measurement of three kinds of different radials depth of investigetion of method acquisition of electric current focusing.For the coil system of high band, can adopt existing exemplary array: the triple coil cell array.It should be noted that, the electrode in Fig. 8, coil width and adjacent structure separately is only signal, and width and the adjacent structure that in fact can easily expect with other those skilled in the art design combination electrode, substantially can realize same effect.

The present invention for the combination electrode preferred embodiment of surveying bottom as shown in Figure 9.In this combination electrode, it is non-closing structure that electrode part divides the cylinder in the outside, is respectively pole plate 1, the axle 2 in the axle center that center is penetrating electrode place cylinder.This axle is preferably cylindricality, and the diameter of this columnar shaft xsect is less than the diameter of the xsect of electrode outside pole plate 1 place cylindricality.Described diameter requires as far as possible little in principle, but again can not be too little after the consideration requirement of mechanical strength.Each pole plate 1 in the described electrode outside by one with it corresponding connecting rod 3 with described axle, be connected.

When with coil when transmitting and receiving signal, what measure is the induction electromotive force that eddy current that alternating electromagnetic field that transmitting coil produces in space evokes at stratum media produces at receiving coil as new driving source, thereby come the size of the eddy current on reverse stratum to determine formation conductivity (or inverse of resistivity) with this, and electrode has become height to lead medium in coil is measured, form and disturb to received signal, this disturbs with lithostratigraphy and has nothing to do simultaneously, thereby must reduce as far as possible.The size of the interference that electrode produces is relevant with electrode diameter, and the undesired signal of less its generation of electrode diameter is just less, therefore, preferably electrode is made to structure as shown in Figure 9, reduces the diameter of a circle that it forms circumferential closure.

The present invention is for surveying the another preferred embodiment of combination electrode of bottom, as shown in figure 10.Shown combination electrode in Figure 10, its electrode and coil are crisscross arranged.In Figure 10, A0, A1, A2, A3, A ' 1, and A ' 2, and A'3 is electrode, T, B1, R2, B2, R2, B3, R3 is coil.In coil, T is transmitting coil, and B is for offsetting straight coupling coil, and R is receiving coil.Coil R is is generally transmitting and receiving between coil for offsetting straight coupling coil B.Arrange like this, can avoid electrode and coil overlapping, facilitate the making of combination electrode.

The present invention also provides detector embodiment.The combination electrode comprised in this detector embodiment, and this combination electrode can be above-mentioned various combination electrode embodiment any.

This detector in use, should provide transmitting and receiving of the electric signal of frequency from 10Hz～10MHz scope, and at least have three different investigation depths, is conducive to the existence of quicklook ground judgement oil gas.The darkest investigation depth is not less than 1.5 meters.Investigation depth requires deeply just can detect the stratum of virgin state, and different investigation depths provide stratum the drilled circumocular situation of change that drives a well.

As seen through the above description of the embodiments, those skilled in the art can be well understood to the mode that the present invention can add essential general hardware platform by software and realizes.Understanding based on such, the part that technical scheme of the present invention contributes to prior art in essence in other words can embody with the form of software product, this computer software product can be stored in storage medium, as ROM/RAM, magnetic disc, CD etc., comprise that some instructions are with so that a computer equipment (can be personal computer, server, or the network equipment etc.) carry out the described method of some part of each embodiment of the present invention or embodiment.

Each embodiment in this instructions all adopts the mode of going forward one by one to describe, and between each embodiment, identical similar part is mutually referring to getting final product, and each embodiment stresses is the difference with other embodiment.Especially, for system embodiment, due to it, substantially similar in appearance to embodiment of the method, so description is fairly simple, relevant part gets final product referring to the part explanation of embodiment of the method.

The present invention can be used in numerous general or special purpose computingasystem environment or configuration.For example: personal computer, server computer, handheld device or portable set, plate equipment, multicomputer system, the system based on microprocessor, set top box, programmable consumer-elcetronics devices, network PC, small-size computer, mainframe computer, comprise distributed computing environment of above any system or equipment etc.

The present invention can describe in the general context of the computer executable instructions of being carried out by computing machine, for example program module.Usually, program module comprises the routine carrying out particular task or realize particular abstract data type, program, object, assembly, data structure etc.Also can in distributed computing environment, put into practice the present invention, in these distributed computing environment, be executed the task by the teleprocessing equipment be connected by communication network.In distributed computing environment, program module can be arranged in the local and remote computer-readable storage medium that comprises memory device.

Although described the embodiment of the present invention by embodiment, those of ordinary skills know, the present invention has many distortion and variation and do not break away from spirit of the present invention, wish that appended claim comprises these distortion and variation and do not break away from spirit of the present invention.

Claims (10)

1. a method of surveying stratum, is characterized in that, comprising:

S1: to formation at target locations emission measurement signal;

S2: the measuring-signal of measuring described emission reflects vector current potential and the vector current of the reflected signal obtained through described formation at target locations;

S3: the first complex resistivity that obtains formation at target locations according to vector current potential and the vector current of described reflected signal;

S4: set a water saturation S _winitial value, utilize following formula to obtain the second complex resistivity:

${{\mathrm{\&rho;}}^{*}}_2\left(\mathrm{\&omega;}\right)=\frac{\mathrm{ab}{R}_W}{{\mathrm{\&phi;}}^m{S}_W^n}[1-{\mathrm{\&eta;}}_1(1-\frac{1}{1+{\left(\mathrm{j\&omega;}{\mathrm{\&tau;}}_1\right)}^{c_1}})]\&times;[1-{\mathrm{\&eta;}}_2(1-\frac{1}{1+{\left(\mathrm{j\&omega;}{\mathrm{\&tau;}}_2\right)}^{c_2}})]$

In above formula, ρ ^* ₂(ω) be the second complex resistivity, the angular frequency that ω is electric field, j is imaginary unit; τ ₁, τ ₂be respectively the first relaxation time, the second relaxation time; η ₁, η ₂be respectively the first polarizability and the first polarizability; c ₁, c ₂be respectively first frequency related coefficient and second frequency related coefficient; R _wit is formation water resistivity; φ is formation porosity; A, b are coefficient; M, n are provisional index;

S5: when the difference of the first complex resistivity and the second complex resistivity is less than or equal to predetermined value, determine current S _wvalue is the water saturation value of formation at target locations; When the difference of the first complex resistivity and the second complex resistivity is greater than predetermined value, to be scheduled to step-length, adjust S _wvalue, until the difference of the first complex resistivity and the second complex resistivity is while being less than or equal to predetermined value, definite S now _wvalue is the water saturation value of formation at target locations;

S6: the hydrocarbon saturation value that obtains formation at target locations according to the water saturation value of definite formation at target locations.

2. the method for claim 1 is characterized in that:

Described measuring-signal comprises single-frequency and/or multifrequency signal;

The signal of described single-frequency comprises low frequency and/or high-frequency signal;

Described multifrequency signal comprises multifrequency low frequency signal, or multifrequency high-frequency signal, or has the multifrequency signal of low frequency signal and high-frequency signal concurrently.

3. the method for claim 1, is characterized in that, adopts inductolog or electromagnetic wave logging mode to receive described reflected signal.

4. the method for claim 1, is characterized in that, described predetermined step-length is fixed value, or be a series of different value.

5. a method of calculating the stratum hydrocarbon saturation, is characterized in that, comprising:

S1: obtain vector current potential and the vector current of reflected signal, obtain the first complex resistivity of formation at target locations;

S2: set water saturation S _winitial value, utilize following formula to obtain the second complex resistivity:

${{\mathrm{\&rho;}}^{*}}_2\left(\mathrm{\&omega;}\right)=\frac{\mathrm{ab}{R}_W}{{\mathrm{\&phi;}}^m{S}_W^n}[1-{\mathrm{\&eta;}}_1(1-\frac{1}{1+{\left(\mathrm{j\&omega;}{\mathrm{\&tau;}}_1\right)}^{c_1}})]\&times;[1-{\mathrm{\&eta;}}_2(1-\frac{1}{1+{\left(\mathrm{j\&omega;}{\mathrm{\&tau;}}_2\right)}^{c_2}})]$

In above formula, ρ ^* ₂(ω) be the second complex resistivity, the angular frequency that ω is electric field, j is imaginary unit; τ is relaxation time; η is polarizability; C is frequency correlation coefficient; R _wit is formation water resistivity; φ is formation porosity; A, b are coefficient; M, n are provisional index;

S3: when the difference of the first complex resistivity and the second complex resistivity is less than or equal to predetermined value, determine current S _wvalue is the water saturation value of formation at target locations; When the difference of the first complex resistivity and the second complex resistivity is greater than predetermined value, to be scheduled to step-length, adjust S _wvalue, until the difference of the first complex resistivity and the second complex resistivity is while being less than or equal to predetermined value, definite S now _wvalue is the water saturation value of formation at target locations;

S4: the hydrocarbon saturation value that obtains formation at target locations according to the water saturation value of definite formation at target locations.

6. a combination electrode that is applied to the described method of any one in the claims 1-5, is characterized in that, this combination electrode comprises the composite structure of electrode and coil.

7. combination electrode as claimed in claim 6, is characterized in that, described electrode part divides each pole plate that the cylinder in the outside is non-closing structure, the axle in the axle center that center is penetrating electrode place cylinder; This axle is cylindricality, and the diameter of this columnar shaft xsect is less than the diameter of the xsect of described pole plate place cylindricality; Each pole plate in the described electrode outside by one with it corresponding connecting rod with described axle, be connected.

8. combination electrode as described as claim 6 or 7, is characterized in that, described electrode and coil are crisscross arranged.

9. combination electrode as described in claim 8, is characterized in that, described electrode part divides the outside to be added with dielectric film or cutting.

10. a detector, is characterized in that, comprises combination electrode as described as any one in claim 6-9.

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