CN1248016C - Synthetic focusing method for excited polarized logging - Google Patents

Abstract

The present invention relates to a synthetic focusing method for excited polarization well logging, which divides the well logging into two partial fields, wherein the first partial field transmits constant electric current by a main electrode, a shielding electrode does not transmit electric current, and partial field excited polarization electric potential on a monitoring electrode corresponding to the first partial field and a secondary electric potential attenuation curve after power cut are recorded; the second partial field transmits constant electric current by a shielding electrode, a main electrode does not transmit electric current, and the secondary partial field electric potential attenuation curve is fitted to obtain secondary electric potential amplitude. The secondary partial field electric potential is equivalent to the partial field excited polarization electric potential to obtain an excited polarization electric potential curve during partial field electricity supply, and then, an electric field is superposed to supervise electrode electric potential focusing, synthesize polarization total field electric potential and obtain primary electric potential, excited polarization total field electric potential and a secondary electric potential attenuation curve after the focusing. The present invention can effectively reduce the influences of a wellbore, wall rocks and an invaded zone on the well logging to improve measurement precision, the detection depth can reach 2.4 meters, and the stratification can reach 0.5 meter. The present invention provides important well logging information for residual oil distribution and thick stratum subdivision in a period of high water contents.

Description

The synthetic focusing method of induced polarization log

Technical field

The present invention relates to the logging technology of petroleum geology exploration and metal mineral reserves exploration, particularly a kind of synthetic focusing method that can be used for the induced polarization log of dark survey and shallow survey.

Background technology

The induced polarization log method is the comparatively ripe electric logging technology of using at present, and its principle is to apply a constant external electric field in by well logging, the current potential after record power supply and the outage, and then calculate parameter such as formation conductivity.The existing induced polarization log method in home and abroad has only single electric field non-focusing method, apply a constant external electric field at first for the sand shale stratum, make it to produce polarization field, that is electricity layer deformation of generation idol and local concentration change, when extra electric field is disconnected go after because the diffusion of ion, ion concentration gradient will fade away, be that secondary field is decayed gradually, return to original state of nature.

If measured passive system is linear, and do not consider electro-kinetic effect influence, Δ U (t) curve and U during power supply ₂(t) die-away curve is corresponding consistent, like this, and polarized potential: U ₂=U _P-U ₁, polarizability:

$\mathrm{\η}=\frac{U_2}{U_P}=\frac{U_P-U_1}{U_P}\×100\%.$

Actual conditions at well logging (contain well, country rock, invaded zone etc.), as long as when finding the solution the Laplace's equation formula, the ground electricity condition of being given is also identical with the boundary condition of solving a problem, then just can replace resistivity, thereby, look equivalent resistivity by primary field expression formula just directly obtain the polarizing expression formula of resultant field with equivalent resistivity: ${{\mathrm{\ρ}}_a}^{*}=\frac{{\mathrm{\ρ}}_a}{1-{\mathrm{\η}}_a},$ Apparent chargeability: ${\mathrm{\η}}_a=\frac{{{\mathrm{\ρ}}_a}^{*}-{\mathrm{\ρ}}_a}{{{\mathrm{\ρ}}_a}^{*}}.$

Above measuring method is subject to the influence of well, country rock and invaded zone, and resolution and measuring accuracy are not high, and investigation depth only is a 0.6-0.8 rice, and bed resolution only is 1 meter, thereby has limited practical ranges.

Summary of the invention

The purpose of this invention is to provide and a kind ofly can be used for dark the survey and shallow survey, reduce the influence of well, country rock and invaded zone, the synthetic focusing method of the induced polarization log of raising bed resolution and measuring accuracy induced polarization log.

The object of the present invention is achieved like this:

Electrode system of the present invention is embedded on the columniform insulation rod, is central electrode A ₀, two couples of monitor electrode M ₁, M ₁' and M ₂, M ₂', two couples of guarded electrode A ₁, A ₁' and A ₂, A ₂', be the center with the central electrode, every pair of relative central electrode of electrode is arranged symmetrically, and short circuit mutually between the every pair of electrode, and B is the current supply circuit electrode, and N is for measuring loop electrode;

Well logging is divided into two another arenaes, twice measurement, first another arena is by central electrode A ₀Emission steady current I ₀, and guarded electrode A ₁, A ₁' and A ₂, A ₂' transmitter current not writes down its corresponding monitor electrode M ₁, M ₁' and M ₂, M ₂' on another arena induced polarization current potential and the outage after the secondary electric potential die-away curve;

Second another arena is by guarded electrode A ₁, A ₁' and A ₂, A ₂' emission steady current I ₁, and central electrode A ₀Transmitter current does not write down its corresponding monitor electrode M ₁, M ₁' and M ₂, M ₂' on another arena induced polarization current potential and the outage after the secondary electric potential die-away curve;

Match secondary another arena potential decay curve, obtain its secondary electric potential amplitude, divide the field potential equivalence to another arena induced polarization current potential secondary, induced polarization potential curve when obtaining the another arena power supply, again by the electric field superposition with utilize monitor electrode current potential focused condition, the total field potential of synthetic polarization, a current potential after obtaining focusing on, the total field potential of induced polarization and secondary electric potential die-away curve, resistivity and polarizability logging trace after also can obtaining focusing on.

Purpose of the present invention can also realize like this:

Well logging can be divided into the another arena more than three or three, measure the back match.

With central electrode A ₀, guarded electrode A ₁, and guarded electrode A ₂Power separately as three another arenaes, measure the branch field potential on monitor electrode and the transmitting electrode.

The present invention reduces well, country rock and invaded zone effectively to well logging influence, raising bed resolution and measuring accuracy, and investigation depth can reach 2.4 meters, 0.5 meter of bed resolution Gao Keda.This method make to focus on induced polarization log and is achieved, for the remaining oil distribution and the thick zone subdivision of high water-cut stage provides how prior well logging information.

Description of drawings

Fig. 1 is an electrode system synoptic diagram of the present invention;

Secondary electric potential die-away curve figure after charging curve when Fig. 2 is power supply and the outage.

Inventive embodiments

The present invention is further detailed explanation below in conjunction with the drawings and specific embodiments.

Electrode system of the present invention has nine ring electrodes, is embedded on the columniform insulation rod.Central electrode is A ₀, M ₁, M ₁' and M ₂, M ₂' be two pairs of monitor electrodes, two pairs of guarded electrodes are A ₁, A ₁' and A ₂, A ₂', be the center with the central electrode, with each to the relative A of electrode ₀Electrode is arranged symmetrically, and short circuit mutually between the every pair of electrode.B is the current supply circuit electrode, and N is for measuring loop electrode.

The object of the present invention is achieved like this: no matter be dark the survey or shallow survey, all induced polarization log be divided into two another arenaes or a plurality of another arena, power separately and measure the branch field potential.First another arena is by central electrode A ₀Emission steady current I ₀, and guarded electrode A ₁, A ₁' and A ₂, A ₂' transmitter current not writes down its corresponding monitor electrode M ₁, M ₁' and M ₂, M ₂' on another arena induced polarization current potential and the outage after the secondary electric potential die-away curve; Second another arena has only guarded electrode emission steady current I ₁, and central electrode A ₀Transmitter current not writes down another arena induced polarization current potential on its corresponding monitor electrode and the secondary electric potential die-away curve after the outage.Match another arena secondary electric potential die-away curve obtains its secondary electric potential amplitude.With another arena secondary electric potential equivalence to another arena induced polarization current potential, induced polarization potential curve in the time of can obtaining the another arena power supply, utilize electric field superposition principle and monitor electrode equipotential to focus on synthesis condition again, the total field potential of synthetic polarization, just a current potential after can obtaining focusing on, the total field potential of induced polarization and secondary electric potential die-away curve, resistivity and polarizability logging trace after also can obtaining focusing on.Thereby the focusing induced polarization log is achieved.

In power supply process,, form polarization field because rock and ore under constant External Electrical Field, ionic polarization takes place.If the passive system of being studied is linear, and do not consider the electro-kinetic effect influence, secondary electric potential die-away curve after charging curve when then powering and the outage is corresponding consistent, that is can be with the secondary electric potential die-away curve (or being called discharge curve) after the outage corresponding equivalence be induced polarization potential curve (or being called charging curve) when powering.

Because what central electrode and guarded electrode sent all is steady current, under stable case, its field that produces in the stratum is quasi-static field.For the formed electric field of steady current, the differential equation of primary field and induced polarization resultant field, interface condition and boundary condition, they all are the linear representations about unknown function u and derivative thereof, promptly this consideration be the linear differential equation and linear boundary condition, thereby satisfy the electric field superposition principle.The linear superposition of the another arena polarized potential that the combined potential of polarization resultant field produces when equaling each electrode and powering separately.

U _PTFor the another arena polarized potential, mean U _PT0(M ₁), U _PT0(M ₂), U _PT1(M ₁), U _PT1(M ₂), U _RTBe the current potential in another arena, U _2T(t) for the another arena secondary electric potential die-away curve after the outage, mean U _2T0(M ₁, t), U _2T0(M ₂, t), U _2T1(M ₁, t), U _2T1(M ₂, t).As shown in the figure, apply a constant external electric field at first for the sand shale stratum, make it to produce polarization field, that is electricity layer deformation of generation idol and local concentration change, when extra electric field is disconnected go after because the diffusion of ion, ion concentration gradient will fade away, be that secondary field is decayed gradually, return to original state.

Optimum implementation of the present invention is with the equal short circuit of all symmetry electrodes, when surveying deeply with A ₁And A ₂Short circuit is as guarded electrode, and B is the current supply circuit electrode; During shallow survey with A ₁As guarded electrode, A ₂Be the current supply circuit electrode.In the another kind of power supply mode, also can be with central electrode A ₀, guarded electrode A ₁, and guarded electrode A ₂Power separately as three another arenaes, measure the branch field potential on monitor electrode and the transmitting electrode, utilize method synthetic focusing same as described above.Optimum implementation of the present invention is identical with three another arena synthetic effects, but has reduced the measurement number of times, has improved efficiency of measurement.

Two another arena synthetic method embodiments of the present invention are:

First another arena is by central electrode A ₀Emission steady current I ₀, and guarded electrode transmitter current not writes down its corresponding monitor electrode M ₁And M ₂On another arena induced polarization current potential U _PT0(M ₁), U _PT0(M ₂) and the outage after secondary electric potential die-away curve U _2T0(M ₁, t), U _2T0(M ₂, t); Second another arena has only guarded electrode (A ₁And A ₂Short circuit) emission steady current I ₁, and central electrode A ₀Transmitter current does not write down its corresponding monitor electrode M ₁And M ₂On another arena induced polarization current potential U _PT1(M ₁), U _PT1(M ₂) and the outage after secondary electric potential die-away curve U _2T1(M ₁, t), U _2T1(M ₂, t).Match secondary electric potential die-away curve U _2T0(M ₁, t), U _2T0(M ₂, t), U _2T1(M ₁, t), U _2T1(M ₂, t), obtain its secondary electric potential amplitude U _2T0(M ₁), U _2T0(M ₂), U _2T1(M ₁), U _2T1(M ₂).

Induced polarization potential curve (or being called charging curve) when the corresponding equivalence of the secondary electric potential die-away curve (or being called discharge curve) after the outage of another arena is powered for the another arena:

U _PT0(M ₁，t)＝U _PT0(M ₁)-U _2T0(M ₁，t) (1)

U _PT0(M ₂，t)＝U _PT0(M ₂)-U _2T0(M ₂，t) (2)

U _PT1(M ₁，t)＝U _PT1(M ₁)-U _2T1(M ₁，t) (3)

U _PT1(M ₂，t)＝U _PT1(M ₂)-U _2T1(M ₂，t) (4)

Another arena in the time of can being obtained not having polarization by the secondary electric potential amplitude after another arena polarized potential and the outage is (pure resistance effect) current potential once:

U _RT0(M ₁)＝U _PT0(M ₁)-U _2T0(M ₁) (5)

U _RT0(M ₂)＝U _PT0(M ₂)-U _2T0(M ₂) (6)

U _RT1(M ₁)＝U _PT1(M ₁)-U _2T1(M ₁) (7)

U _RT1(M ₂)＝U _PT1(M ₂)-U _2T1(M ₂) (8)

According to the electric field superposition principle, one time the current potential composite formula is:

U _RT(M ₁)＝U _RT0(M ₁)+C ₁U _RT1(M ₁) (9)

U _RT(M ₂)＝U _RT0(M ₂)+C ₁U _RT1(M ₂) (10)

The equipotential focused condition is:

U _RT(M ₁)＝U _RT(M ₂) (11)

Can get primary field composite coefficient and potential focus is:

$C_1=\frac{U_{\mathrm{RT}0}\left(M_1\right)-U_{\mathrm{RT}0}\left(M_2\right)}{U_{\mathrm{RT}1}\left(M_2\right)-U_{\mathrm{RT}1}\left(M_1\right)}---\left(12\right)$

U _RT＝U _RT(M ₁)＝U _RT(M ₂) (13)

By another arena polarized potential composite formula

U _PT(M ₁)＝U _PT0(M ₁)+C ₂U? _PT1(M ₁) (14)

U _PT(M ₂)＝U _PT0(M ₂)+C ₂U? _PT1(M ₂) (15)

And equipotential focused condition:

U _PT(M ₁)＝U _PT(M ₂) (16)

Resultant field composite coefficient and potential focus can polarize:

$C_2=\frac{U_{\mathrm{PT}0}\left(M_1\right)-U_{\mathrm{PT}0}\left(M_2\right)}{U_{\mathrm{PT}1}\left(M_2\right)-U_{\mathrm{PT}1}\left(M_1\right)}---\left(17\right)$

U _PT＝U _PT(M ₁)＝U _PT(M ₂) (18)

By the instantaneous polarized potential composite formula in another arena:

U _PT(M ₁，t)＝U _PT0(M ₁，t)+Ci*U _PT1(M ₁，t) (19)

U _PT(M ₂，t)＝U _PT0(M ₂，t)+Ci*U _PT1(M ₂，t) (20)

And equipotential focused condition:

U _PT(M ₁，t)＝U _PT(M ₂，t) (21)

Instantaneous composite coefficient of resultant field and potential focus can polarize:

$\mathrm{Ci}=\frac{U_{\mathrm{PT}0}(M_1,t)-U_{\mathrm{PT}0}(M_2,t)}{U_{\mathrm{PT}1}(M_2,t)-U_{\mathrm{PT}1}(M_1,t)}---\left(22\right)$

U _PT(t)＝U _PT(M ₁，t)＝U _PT(M ₂，t) (23)

Thereby the resistivity that obtains behind the synthetic focusing is:

Rt＝K*U _RT/I _A0 (24)

K is the instrument coefficient.

Secondary electric potential amplitude and die-away curve thereof behind the synthetic focusing are:

U _2T＝U _PT-U _RT (25)

U _2T(t)＝U _PT-U _PT(t) (26)

Polarizability amplitude and die-away curve thereof behind the synthetic focusing are:

η _2T＝U _2T*100/U _PT (27)

η _2T(t)＝U _2T(t)*100/U _PT (28)

Three another arena synthetic method embodiments of the present invention are:

First another arena is by central electrode A ₀Emission steady current I ₀, and guarded electrode transmitter current not writes down its corresponding monitor electrode Mx ₁, M ₂And A ₁, A ₂On another arena induced polarization current potential U _PT0(M ₁), U _PT0(M ₂), U _PT0(A ₁), U _PT0(A ₂) and the outage after secondary electric potential die-away curve U _2T0(M ₁, t), U _2T0(M ₂, t), U _2T0(A ₁, t), U _2T0(A ₂, t); Second another arena has only guarded electrode A ₁Emission steady current I ₁, and central electrode A ₀With guarded electrode A ₂Transmitter current does not write down its corresponding monitor electrode M ₁, M ₂And A ₁, A ₂On another arena induced polarization current potential U _PT1(M ₁), U _PT1(M ₂), U _PT1(A ₁), U _PT1(A ₂) and the outage after secondary electric potential die-away curve U _2T1(M ₁, t), U _2T1(M ₂, t), U _2T1(A ₁, t), U _2T1(A ₂, t); The 3rd another arena has only guarded electrode A ₂Emission steady current I ₂, and central electrode A ₀With guarded electrode A ₁Transmitter current does not write down its corresponding monitor electrode M ₁, M ₂And A ₁, A ₂On another arena induced polarization current potential U _PT2(M ₁), U _PT2(M ₂), U _PT2(A ₁), U _PT2(A ₂) and the outage after secondary electric potential die-away curve U _2T2(M ₁, t), U _2T2(M ₂, t), U _2T2(A ₁, t), U _2T2(A ₂, t);

Match secondary electric potential die-away curve U _2T0(M ₁, t), U _2T0(M ₂, t), U _2T0(A ₁, t), U _2T0(A ₂, t), U _2T1(M ₁, t), U _T1(M ₂, t), U _2T1(A ₁, t), U _2T1(A ₂, t), U _2T2(M ₁, t), U _2T2(M ₂, t), U _2T2(A ₁, t), U _2T2(A ₂, t), obtain its secondary electric potential amplitude U _2T0(M ₁), U _2T0(M ₂), U _2T0(A ₁), U _2T0(A ₂), U _2T1(M ₁), U _2T1(M ₂), U _2T1(A ₁), U _2T1(A ₂), U _2T2(M ₁), U _2T2(M ₂), U _2T2(A ₁), U _2T2(A ₂).

Induced polarization potential curve (or being called charging curve) when the corresponding equivalence of the secondary electric potential die-away curve (or being called discharge curve) after the outage of another arena is powered for the another arena:

$\left\{\begin{array}{c}{U}_{\mathrm{PT}0}(M_1,t)=U_{\mathrm{PT}0}\left(M1\right)-U_{2T0}(M_1,t)\\ U_{\mathrm{PT}0}(M_2,t)=U_{\mathrm{PT}0}\left(M_2\right)-U_{2T0}(M_2,t)\\ U_{\mathrm{PT}0}(A_1,t)=U_{\mathrm{PT}0}\left(A_1\right)-U_{2T0}(A_1,t)\\ U_{\mathrm{PT}0}(A_2,t)=U_{\mathrm{PT}0}\left(A_2\right)-U_{2T0}(A_2,t)\\ U_{\mathrm{PT}1}(M_1,t)=U_{\mathrm{PT}1}\left(M_1\right)-U_{2T1}(M_1,t)\\ U_{\mathrm{PT}1}(M_2,t)=U_{\mathrm{PT}1}\left(M_2\right)-U_{2T1}(M_2,t)\\ U_{\mathrm{PT}1}(A_1,t)=U_{\mathrm{PT}1}\left(A_1\right)-U_{2T1}(A_1,t)\\ U_{\mathrm{PT}1}(A_2,t)=U_{\mathrm{PT}1}\left(A_2\right)-U_{2T1}(A_2,t)\\ U_{\mathrm{PT}2}(M_1,t)=U_{\mathrm{PT}2}\left(M_1\right)-U_{2T2}(M_1,t)\\ U_{\mathrm{PT}2}(M_2,t)=U_{\mathrm{PT}2}\left(M_2\right)-U_{2T2}(M_2,t)\\ U_{\mathrm{PT}2}(A_1,t)=U_{\mathrm{PT}2}\left(A_1\right)-U_{2T2}(A_1,t)\\ U_{\mathrm{PT}2}(A_1,t)=U_{\mathrm{PT}2}\left(A_2\right)-U_{2T2}(A_2,t)\end{array}\right.---\left(29\right)$

Another arena in the time of can being obtained not having polarization by the secondary electric potential amplitude after another arena polarized potential and the outage is (pure resistance effect) current potential once:

$\left\{\begin{array}{c}{U}_{\mathrm{RT}0}\left(M_1\right)=U_{\mathrm{PT}0}\left(M_1\right)-U_{2T0}\left(M_1\right)\\ U_{\mathrm{RT}0}\left(M_2\right)=U_{\mathrm{PT}0}\left(M_2\right)-U_{2T0}\left(M_2\right)\\ U_{\mathrm{RT}0}\left(A_1\right)=U_{\mathrm{PT}0}\left(A_1\right)-U_{2T0}\left(A_1\right)\\ U_{\mathrm{RT}0}\left(A_2\right)=U_{\mathrm{PT}0}\left(A_2\right)-U_{2T0}\left(A_2\right)\\ U_{\mathrm{RT}1}\left(M_1\right)=U_{\mathrm{PT}1}\left(M_1\right)-U_{2T1}\left(M_1\right)\\ U_{\mathrm{RT}1}\left(M_2\right)=U_{\mathrm{PT}1}\left(M_2\right)-U_{2T1}\left(M_2\right)\\ U_{\mathrm{RT}1}\left(A_1\right)=U_{\mathrm{PT}1}\left(A_1\right)-U_{2T1}\left(A_1\right)\\ U_{\mathrm{RT}1}\left(A_2\right)=U_{\mathrm{PT}1}\left(A_2\right)-U_{2T1}\left(A_2\right)\\ U_{\mathrm{RT}2}\left(M_1\right)=U_{\mathrm{PT}2}\left(M_1\right)-U_{2T2}\left(M_1\right)\\ U_{\mathrm{RT}2}\left(M_2\right)=U_{\mathrm{PT}2}\left(M_2\right)-U2T2\left(M_2\right)\\ U_{\mathrm{RT}2}\left(A_1\right)=U_{\mathrm{PT}2}\left(A_1\right)-U_{2T2}\left(A_1\right)\\ U_{\mathrm{RT}2}\left(A_2\right)=U_{\mathrm{PT}2}\left(A_2\right)-U_{2T2}\left(A_2\right)\end{array}\right.---\left(30\right)$

According to the electric field superposition principle, one time the current potential composite formula is:

U _RT(M ₁)＝U _RT0(M ₁)+D ₁U _RT1(M ₁)+D ₂U _RT2(M ₁) (31)

U _RT(M ₂)＝U _RT0(M ₂)+D ₁U _RT1(M ₂)+D ₂U _RT2(M ₂) (32)

U _RT(A ₁)＝U _RT0(A ₁)+D ₁U _RT1(A ₁)+D ₂U _RT2(A ₁) (33)

U _RT(A ₂)＝U _RT0(A ₂)+D ₁U _RT1(A ₂)+D ₂U _RT2(A ₂) (34)

The equipotential focused condition is:

U _RT(M ₁)＝U _RT(M ₂) (35)

U _RT(A ₁)＝U _RT(A ₂) (36)

Can get primary field composite coefficient D1, D2 and potential focus by current potential composite formula and equipotential focused condition.

By another arena polarized potential composite formula

U _PT(M ₁)＝U _PT0(M ₁)+D ₃U _PT1(M ₁)+D ₄U _PT2(M ₁) (37)

U _PT(M ₂)＝U _PT0(M ₂)+D ₃U _PT1(M ₂)+D ₄U _PT2(M ₂) (38)

U _PT(A ₁)＝U _PT0(A ₁)+D ₃U _PT1(A ₁)+D ₄U _PT2(A ₁) (39)

U _PT(A ₂)＝U _PT0(A ₂)+D ₃U _PT1(A ₂)+D ₄U _PT2(A ₂) (40)

And equipotential focused condition:

U _PT(M ₁)＝U _PT(M ₂) (41)

U _PT(A ₁)＝U _PT(A ₂) (42)

Resultant field composite coefficient D can polarize ₃, D ₄And potential focus:

By the instantaneous polarized potential composite formula in another arena:

U _PT(M ₁，t)＝U _PT0(M ₁，t)+D _i1*U _PT1(M ₁，t)+D _i2*U _PT2(M ₁，t) (43)

U _PT(M ₂，t)＝U _PT0(M ₂，t)+D _i1*U _PT1(M ₂，t)+D _i2*U _PT2(M ₂，2) (44)

And equipotential focused condition:

U _PT(M ₁，t)＝U _PT(M ₂，t) (45)

U _PT(A ₁，t)＝U _PT(A ₂，t) (46)

The instantaneous composite coefficient D of the resultant field that can polarize _I1, D _I2And potential focus.

The resistivity that in like manner can obtain behind the synthetic focusing is:

R _t＝K*U _RT/I _A0

K is the instrument coefficient.

Secondary electric potential amplitude and die-away curve thereof behind the synthetic focusing are:

U _2T＝U _PT-U _RT

U _2T(t)＝U _PT-U _PT(t)

Polarizability amplitude and die-away curve thereof behind the synthetic focusing are:

η _2T＝U _2T*100/U _PT

η _2T(t)＝U _2T(t)*100/U _PT

Analogize according to embodiment 1 and 2, the present invention can have n to guarded electrode (... An, An '), can divide n measurement, forms a plurality of another arenaes, organizes parameter fitting more.

Claims (1)

1, a kind of synthetic focusing method of induced polarization log comprises current supply circuit electrode (B) and measures the electrode system of loop electrode (N) that electrode system is embedded on the columniform insulation rod, is central electrode (A ₀), two couples of monitor electrode (M ₁, M ₁' and M ₂, M ₂'), two couples of guarded electrode (A ₁, A ₁' and A ₂, A ₂'), be the center with the central electrode, every pair of relative central electrode of electrode is arranged symmetrically, and short circuit mutually between the every pair of electrode, it is characterized in that: well logging is divided into two another arenaes, twice measurement, first another arena is by central electrode (A ₀) emission steady current (I ₀), and guarded electrode (A ₁, A ₁' and A ₂, A ₂') transmitter current not, write down its corresponding monitor electrode (M ₁, M ₁' and M ₂, M ₂') on another arena induced polarization current potential and the outage after the secondary electric potential die-away curve; Second another arena is by guarded electrode (A ₁, A ₁' and A ₂, A ₂') emission steady current (I ₁), and central electrode (A ₀) transmitter current not,

Write down its corresponding monitor electrode (M ₁, M ₁' and M ₂, M ₂') on another arena induced polarization current potential and the outage after the secondary electric potential die-away curve; Match secondary another arena potential decay curve, obtain its secondary electric potential amplitude, divide the field potential equivalence to another arena induced polarization current potential secondary, induced polarization potential curve when obtaining the another arena power supply, superposition electric field and monitor electrode current potential focus on again, the total field potential of synthetic polarization, a current potential after obtaining focusing on, the total field potential of induced polarization and secondary electric potential die-away curve, resistivity and polarizability logging trace after also can obtaining focusing on;

Plural guarded electrode (A ₁, A ₁', A ₂, A ₂' ... A _n, A _n') respectively (n) repeatedly launch steady current (I _n), well logging is divided into three or (n) a plurality of above another arenaes, match after the measurement respectively;

Can be during shallow survey with guarded electrode (A ₂, A ₂') respectively as the current supply circuit electrode of two another arenaes.

Images