CN102012526A - Method for discriminating type of reservoir fluid by using resistivity data - Google Patents

Abstract

The invention discloses a method for discriminating the type of reservoir fluid by using resistivity data, which relates to the technical field of oil and gas logging as well as geology and core experiment analysis, and comprises the steps of: a, logging the well through scaling core data, and correctly calculating the mud content, the rock constituents and the porosity of the reservoir fluid; b, eliminating the influence from the lithology and the porosity to the resistivity; c, obtaining m, a, n and b by using core experiment to reflect the parameters of the pore structure, calculating the lower limit RR of the gas-layer resistivity, and eliminating the influence from the pore structure to the resistivity; and d, discriminating the type of the reservoir fluid through comparing a deep lateral resistivity RT in deep induction with the lower limit RR of the gas-layer resistivity obtained in the step c. The method eliminates the influence from the non-fluid factors such as the lithology, the porosity, and the pore structure and the like to the resistivity, and retains and utilizes the response characteristics of different fluids for the resistivity so as to greatly improve the coincidence rate of the discriminating the type of the reservoir fluid.

Description

Adopt resistivity data to carry out the method for distinguishing reservoir fluid type

Technical field

The present invention relates to petroleum gas well logging, geology and rock core test analysis technical field, exactly relate to a kind of method that adopts resistivity data accurately to discern fluid type of reservoir through such as gas-bearing formation, oil reservoir and water layer.

Background technology

Resistivity-gas (oil) layer lower limit resistivity fluid diagnostic method belongs to scientific research and innovation in the petroleum natural gas exploration field, mainly be to utilize high-new well-log information, geologic information and core experiment data, research rock gas (oil), stratum water or other fluid factor and lithology, factor of porosity, the resistivity response feature and the influence degree of nonfluid factors such as pore texture, the nonfluid response factor of getting rid of resistivity value, finally extract the resistivity response attribute of reflection fluid type, and this attribute number value, thereby fast, accurately discern gas-bearing formation, oil reservoir and water layer, for oil and gas development provides formation testing layer position, and then instruct oilfield prospecting developing.

Resistivity data convection cell type reflection is responsive, and the response characteristic difference of gas (oil) layer, water layer, is that fluid type is differentiated one of the most frequently used method.But resistivity data is subjected to nonfluid factor affecting such as lithology, factor of porosity, pore texture big simultaneously, usually makes the distinguishing reservoir fluid type coincidence rate not high, and production brings very big difficulty to oil-gas field development.Differentiate coincidence rate in order to improve fluid type, so need to get rid of the influence of above-mentioned nonfluid factor to resistivity, reservation and utilization are to the response characteristic of resistivity different fluid.

Publication number is CN1243958, and the Chinese patent literature that open day is on February 9th, 2000 discloses a kind of equipment of discerning the borehole measurement method of properties of fluid in bearing stratum and implement this method in the petroleum geology exploration exploitation.Measuring method is to import the recombination current of at least two kinds of frequencies simultaneously to tested reservoir, receive the signal that respective frequencies produces, relatively the big bright properties of fluid in bearing stratum of well segment table of its amplitude difference is an oil (gas), and the bright properties of fluid in bearing stratum of well segment table that its amplitude difference is little is a water.The equipment work principle of implementing this method and the instrument class of existing Formation Resistivity Measurement seemingly, its principle of work feature is to have to tested reservoir to supply with the ability of recombination current of at least two kinds of frequencies and the ability that the respective frequencies measuring-signal is put in sorting in order.But this method is not still got rid of the influence of nonfluid factors such as lithology, factor of porosity, pore texture to resistivity, and the distinguishing reservoir fluid type coincidence rate is still low.

Summary of the invention

For solving the problems of the technologies described above, the present invention proposes a kind of method that adopts resistivity data to carry out distinguishing reservoir fluid type, can get rid of of the influence of nonfluid factors such as lithology, factor of porosity, pore texture to resistivity, keep and utilize response characteristic, thereby can improve the distinguishing reservoir fluid type coincidence rate greatly the resistivity different fluid; And this method can reflect fluid type with numerical values recited, fluid is differentiated by the qualitative of prior art have been brought up to quantitatively, use more convenient more easy to operate on the one hand, on the other hand, can combine this numerical value and seismic data, carry out the prediction of gas (oil) water in the plane, the well logging fluid is differentiated be converted into complanation, improved directive function greatly oilfield prospecting developing by a peephole view.

The present invention adopts following technical proposals to realize:

A kind of method that adopts resistivity to carry out distinguishing reservoir fluid type is characterized in that step is as follows:

A, by rock core information scale well logging, obtain reservoir shale index, rock composition and factor of porosity accurately;

The well logging of rock core scale is one of logging data processing technology of the extensive utilization of present logging community, can adopt existing rock core scale logging technology; But be more preferably, we have than quantum jump on the basis of original technology, and concrete grammar is as follows:

1. shale index is calculated in rock core information scale well logging

Determine clay type and clay property with rock core data such as rock core X diffraction analysis achievement and electron-microscope scanning analysis results, the analysis-by-synthesis well-log information, preferential logging trace, computing method and the processing parameter that calculates shale index, and demarcate the shale index numerical value that well logging is calculated with core analysis shale index numerical value, fine setting shale processing parameter and disposal route, shale index and result of core analysis error minimum (satisfying predefined standard) that well logging is calculated.

Can directly calculate shale index (this is common method) with well-log informations such as natural gamma, spontaneous potential, resistivity for conventional stratum.

For being rich in radioactivity stratum such as feldspar, mica,, can not directly calculate shale index with the individual event well-log information because its natural gamma value is high especially.Mainly contain two class methods:

One class: when the power spectrum data, analyze the kind and the character of non-shale radiomaterial in the stratum earlier, find out and shale radioactivity difference.According to clay type and clay property, select for use thorium, potassium, no uranium gamma to calculate shale index.Based on thorium, just select potassium curve calculation shale index as the radioactivity of non-shale composition; The radioactivity of non-shale composition is just selected thorium curve calculation shale index based on potassium; If not radiothorium, the potassium of shale composition have, as potassium feldspar, because feldspar uranium-bearing not is different fully with shale, therefore the relative content of available uranium is indicated shale.Computing formula is:

$\mathrm{SH}=\frac{\mathrm{SPECT}-{\mathrm{SPECT}}_{\mathrm{nin}}}{{\mathrm{SPECT}}_{\max }-{\mathrm{SPECT}}_{\min }}$

In the formula: V _SH-stratum shale index;

The SH-shale index;

SPECT, SPECT _Max, SPECT _Min-be respectively stratum gamma spectra (thorium, potassium or do not have uranium

$V_{\mathrm{SH}}=\frac{2^{\mathrm{GCUR}\×\mathrm{SH}}-1}{2^{\mathrm{GCUR}}-1}$

Curve) log value, maximal value, minimum value.

Another kind of: when not having the power spectrum data, owing to comprise total hydrogen index of water in the neutron data reaction stratum, available neutron data and factor of porosity data simultaneous calculate shale index.When calculating shale index, it is little to select influenced by other factors, can react the factor of porosity data (acoustic logging data or density data) of stratum truth.The formula that neutron and density simultaneous calculate shale index is:

Φ _N＝φ _t(Φ _wS _w+Φ _hS _h)+Φ _shV _sh+Φ _ma(1-φ _t-V _sh)

ρ _b＝φ _t(ρ _wS _w+ρ _hS _h)+ρ _shV _sh+ρ _ma(1-φ _t-V _sh)

In the formula: Φ _N, φ _t, Φ _w, Φ _s, Φ _Sh, Φ _Ma-be respectively total hydrogen index, factor of porosity, the hydrogen index of water, the hydrogen index of hydrocarbon, the hydrogen index of shale, the hydrogen index of rock skeleton;

ρ _b, ρ _w, ρ _h, ρ _Sh, ρ _Ma-be respectively the density of gross density, water, the density of hydrocarbon, the density of shale, the density of rock skeleton;

S _w, S _h, V _Sh-be respectively saturation degree, the shale index of water saturation, hydrocarbon.

2. factor of porosity, permeability, water saturation and rock component content are calculated in rock core scale well logging

At first utilize Mathematical Statistics Analysis methods such as X plot, histogram tentatively to determine interval transit time, neutron, density value and the fluid parameter of shale and skeleton, determine to calculate the method for factor of porosity and rock composition according to the reservoir space characteristic, utilize core analysis factor of porosity data, lithification to analyze rock composition result again and demarcate factor of porosity and the rock component content that well logging is calculated, adjust shale correction parameter, mineral skeleton and fluid parameter, make logging data processing result and result of core analysis satisfy error requirements.

Utilize core analysis factor of porosity and permeability data to return and obtain hole infiltration relation calculating reservoir permeability, and demarcate well logging result of calculation with the core analysis permeability data.

Utilize the local water analysis of data to obtain formation water resistivity, utilize rock electricity experimental data to obtain reflecting RESERVOIR PORE STRUCTURE and oil, gas, litho-electric parameters m (cementation exponent), the n (saturation exponent) of the distribution of water in hole, a (lithology factor), b (coefficient), calculate water saturation.

B, eliminating lithology and factor of porosity are to the influence of resistivity

1. get rid of the influence of lithology to resistivity

By the relation of each lithology of statistical study and resistivity, resistivity is carried out lithology proofread and correct.Actual and theoretical confirmation, to the resistivity effects maximum in the common lithology is shale.Be that example is illustrated with the shale correction below.

Analyze well-log information as can be known, the principal element that influences shale resistivity is the kind and the percentage composition thereof of the contained clay mineral of shale.As, the smectite content of shale is high more, and its resistivity is low more, and when being mainly smalite, resistivity is higher relatively.So when containing more smectite or illite in the reservoir shale, need carry out shale to resistivity and proofread and correct.General by analysis-by-synthesis clay type and clay property, local water character etc., select for use suitable logging trace and method to carry out shale and proofread and correct.As, be lower than 3 * 10 for common dispersed shale and reservoir water salinity ⁴The stratum of ppm can utilize Xi Mendu equation saturation equation and compensated neutron to calculate shale resistivity, carries out shale and proofreaies and correct:

$\frac{1}{\mathrm{Rxo}}=\frac{{V_{\mathrm{sh}}}^C*S_{\mathrm{XO}}}{\mathrm{Rsh}}+\frac{{\mathrm{\φ}}^2{S_{\mathrm{XO}}}^2}{a{R}_{\mathrm{mf}}(1-{\mathrm{Vsh}}^C)}$

$\mathrm{Sxo}=\frac{{\mathrm{\Φ}}_N-{\mathrm{\Φ}}_{\mathrm{Nma}}(1-\mathrm{\φ}-\mathrm{Vsh})-\mathrm{Vsh}{\mathrm{\Φ}}_{\mathrm{Nsh}}-\mathrm{\φ}{\mathrm{\Φ}}_{\mathrm{Ng}}}{\mathrm{\φ}({\mathrm{\Φ}}_{\mathrm{Nw}}-{\mathrm{\Φ}}_{\mathrm{Ng}})}$

In the formula: R _Xo, R _w, Rsh-is respectively shallow side direction (induction) resistivity, formation water resistivity and shale resistivity;

Φ _Ng, φ _Nw, Φ _Nma, Φ _Nsh-be respectively the neutron hydrogen content of rock gas, local water, rock skeleton and shale;

The Vsh-shale index;

A, C-experience factor often can be 1～2.

Formation resistivity R after shale is proofreaied and correct _cSatisfy following formula:

$\frac{1}{R_c}=\frac{1}{R_t}-\frac{\mathrm{Vcl}}{\mathrm{Rcl}}$

For for simplicity, the resistivity Rsh of the contiguous pure shale layer of also desirable reservoir is as the resistivity of the contained shale of reservoir, tries to achieve formation resistivity R after the correction with following formula again _c

2. get rid of the influence of factor of porosity to resistivity

Log well by the rock core scale, obtain reservoir accurately after factor of porosity, the water saturation data, utilize rock electricity experimental data to obtain the litho-electric parameters (cementation exponent m, saturation exponent n, lithology factor a and coefficient b) of reservoir, the resistivity data (R after the shale correction _c) the substitution Archie equation, try to achieve the resistivity value of each factor of porosity correspondence, by regretional analysis, proofread and correct the influence of factor of porosity to resistivity.

C, utilize core experiment to obtain the parameter of m, a, n, b reflection pore texture, calculate gas-bearing formation resistivity lower limit (RR), the evacuation aperture gap structure is to the influence of resistivity.

Utilize rock core to carry out the experiment of rock electricity and can obtain reflecting RESERVOIR PORE STRUCTURE and oil, gas, the litho-electric parameters of the distribution of water in hole: m (cementation exponent), n (saturation exponent), a (lithology factor), b (coefficient), utilize rock core phase permeability analysis of data to obtain the maximum water saturation data of reservoir, factor of porosity and resistivity data (Rc) the substitution Archie equation after shale is proofreaied and correct, obtained having eliminated lithology like this, the gas-bearing formation lower limit resistivity value of pore texture, by analyzing factor of porosity and this gas-bearing formation lower limit resistivity value, proofread and correct factor of porosity to resistivity effects on the one hand, in addition, recurrence draws the formula that calculates this resistivity value, calculates the continuous gas-bearing formation lower limit resistivity data (RR) identical with well-log information resolution in target well section.

D, the big or small discrimination of reservoir fluid type by the gas-bearing formation lower limit resistivity value (RR) in deep induction (dark side direction) resistivity value (RT) and the c step.

Because the reflection of formation resistivity convection cell is responsive, gas-bearing formation (oil reservoir) resistivity value height, the water layer resistivity value is low, but is subjected to nonfluid factor affecting such as lithology, factor of porosity and pore texture simultaneously.Gas-bearing formation lower limit resistivity value (RR) only needs except nonfluid influence factors such as lithology, factor of porosity and pore textures, and has kept the responsive characteristic of resistivity data convection cell reflection, has promptly kept the Response Property of resistivity value convection cell.Theoretical and a large amount of formation testing result verification, the size of deep induction (dark side direction) resistivity value and gas-bearing formation lower limit resistivity value (RR), can differentiate gas-bearing formation and water layer according to difference, this difference is concrete data, so we can say that this method is with the digitizing of resistivity data convection cell Response Property.Concrete discrimination standard is:

Gas-bearing formation: RT-RR＞0;

Water layer: RT-RR＜0.

Because this method can pointwise be differentiated fluid type on depth section, can accurately determine aerogenesis and the particular location that produces water for air water with layer.

Deep induction (dark side direction) resistivity data is a kind of conventional logging data that obtains by well logging.This method of discrimination also adapts to oil reservoir in theory.

Advantage of the present invention shows:

Adopt A of the present invention, B, four technical schemes that step constituted of C, D compared with prior art, because this method has been got rid of nonfluid influence factors such as lithology, factor of porosity, pore texture when utilizing resistivity data discrimination of reservoir fluid type, grasped the true Response Property of resistivity convection cell type, improved fluid type greatly and differentiated coincidence rate, in 5 peaches, 7 block distinguishing reservoir fluid types are revived in the Su Lige gas field, made coincidence rate bring up to 94% by about 70% of the past.And this method is to quantize to each depth point, with producing reservoir, can know clearly where where water outlet gives vent to anger for some gas (oil) water; In addition, because this method is to reflect fluid type with numerical values recited, fluid is differentiated by the qualitative of past have been brought up to quantitatively, use the more convenient operation that is easier on the one hand, on the other hand, can combine this numerical value and seismic data, carry out the prediction of gas (oil) water in the plane, the well logging fluid is differentiated be converted into complanation, improved directive function greatly oilfield prospecting developing by a peephole view.

Description of drawings

Fig. 1 is 8 sections factor of porosity of 5 trivial boxes of Soviet Union and the gas-bearing formation lower limit resistivity relation figure in the embodiments of the invention

Embodiment

The invention discloses a kind of method that adopts resistivity data to carry out distinguishing reservoir fluid type, step is as follows:

A, by rock core information scale well logging, accurately calculate reservoir shale index, rock composition and factor of porosity;

The well logging of rock core scale is one of logging data processing technology of the extensive utilization of present logging community, can adopt existing rock core scale logging technology; But be more preferably, we have than quantum jump on the basis of original technology, and concrete grammar is as follows:

1. shale index is calculated in rock core information scale well logging

Determine clay type and clay property with rock core data such as rock core X diffraction analysis achievement and electron-microscope scanning analysis results, the analysis-by-synthesis well-log information, preferential logging trace, computing method and the processing parameter that calculates shale index, and demarcate the shale index numerical value that well logging is calculated with core analysis shale index numerical value, fine setting shale processing parameter and disposal route, shale index and result of core analysis error minimum (satisfying predefined standard) that well logging is calculated.

Can directly calculate shale index (common method, computing formula are slightly) with well-log informations such as natural gamma, spontaneous potential, resistivity for conventional stratum.

For being rich in radioactivity stratum such as feldspar, mica,, can not directly calculate shale index with the individual event well-log information because its natural gamma value is high especially.Mainly contain two class methods:

One class is to use the power spectrum data: when the power spectrum data is arranged, analyze the kind and the character of non-shale radiomaterial in the stratum earlier, find out and shale radioactivity difference.According to clay type and clay property, select for use thorium, potassium, no uranium gamma to calculate shale index.Based on thorium, just select potassium curve calculation shale index as the radioactivity of non-shale composition; The radioactivity of non-shale composition is just selected the thorium opisometer based on potassium $\mathrm{SH}=\frac{\mathrm{SPECT}-{\mathrm{SPECT}}_{\mathrm{nin}}}{{\mathrm{SPECT}}_{\max }-{\mathrm{SPECT}}_{\min }}$ Calculate shale index; If not radiothorium, the potassium of shale composition have, as potassium feldspar, because feldspar uranium-bearing not is different fully with shale, therefore the relative content of available uranium is indicated shale.Computing formula is:

In the formula: V _SH-stratum shale index;

The SH-shale index;

SPECT, SPECT _Max, SPECT _Min-be respectively stratum gamma spectra (thorium, potassium or do not have uranium $V_{\mathrm{SH}}=\frac{2^{\mathrm{GCUR}\×\mathrm{SH}}-1}{2^{\mathrm{GCUP}}-1}$ Curve) log value, maximal value, minimum value.

Another kind of: when not having the power spectrum data, owing to comprise total hydrogen index of water in the neutron data reaction stratum, available neutron data and factor of porosity data simultaneous calculate shale index.When calculating shale index, it is little to select influenced by other factors, can react the factor of porosity data (acoustic logging data or density data) of stratum truth.The formula that neutron and density simultaneous calculate shale index is:

Φ _N＝φ _t(Φ _wS _w+Φ _hS _h)+Φ _shV _sh+Φ _ma(1-φ _t-V _sh)

ρ _b＝φ _t(ρ _wS _w+ρ _hS _h)+ρ _shV _sh+ρ _ma(1-φ _t-V _sh)

In the formula: Φ _N, φ _t, Φ _w, Φ _s, Φ _Sh, Φ _Ma-be respectively total hydrogen index, factor of porosity, the hydrogen index of water, the hydrogen index of hydrocarbon, the hydrogen index of shale, the hydrogen index of rock skeleton;

ρ _b, ρ _w, ρ _h, ρ _Sh, ρ _Ma-be respectively the density of gross density, water, the density of hydrocarbon, the density of shale, the density of rock skeleton;

S _w, S _h, V _Sh-be respectively saturation degree, the shale index of water saturation, hydrocarbon.

2. factor of porosity, permeability, water saturation and rock component content are calculated in rock core scale well logging

At first utilize Mathematical Statistics Analysis methods such as X plot, histogram tentatively to determine interval transit time, neutron, density value and the fluid parameter of shale and skeleton, determine to calculate the method for factor of porosity and rock composition according to the reservoir space characteristic, utilize core analysis factor of porosity data, lithification to analyze rock composition result again and demarcate factor of porosity and the rock component content that well logging is calculated, adjust shale correction parameter, mineral skeleton and fluid parameter, make logging data processing result and result of core analysis satisfy error requirements.

Utilize core analysis factor of porosity and permeability data to return and obtain hole infiltration relation calculating reservoir permeability, and demarcate well logging result of calculation with the core analysis permeability data.

Utilize the local water analysis of data to obtain formation water resistivity, utilize rock electricity experimental data to obtain reflecting RESERVOIR PORE STRUCTURE and oil, gas, litho-electric parameters m (cementation exponent), the n (saturation exponent) of the distribution of water in hole, a (lithology factor), b (coefficient), calculate water saturation.

B, eliminating lithology and factor of porosity are to the influence of resistivity

1. get rid of the influence of lithology to resistivity

By the relation of each lithology of statistical study and resistivity, resistivity is carried out lithology proofread and correct.Actual and theoretical confirmation, to the resistivity effects maximum in the common lithology is shale.Be that example is illustrated with the shale correction below.

Analyze well-log information as can be known, the principal element that influences shale resistivity is the kind and the percentage composition thereof of the contained clay mineral of shale.As, the smectite content of shale is high more, and its resistivity is low more, and when being mainly smalite, resistivity is higher relatively.So when containing more smectite or illite in the reservoir shale, need carry out shale to resistivity and proofread and correct.General by analysis-by-synthesis clay type and clay property, local water character etc., select for use suitable logging trace and method to carry out shale and proofread and correct.As, be lower than 3 * 10 for common dispersed shale and reservoir water salinity ⁴The stratum of ppm can utilize Xi Mendu equation saturation equation and compensated neutron to calculate shale resistivity, carries out shale and proofreaies and correct:

$\frac{1}{\mathrm{Rxo}}=\frac{{V_{\mathrm{sh}}}^C*S_{\mathrm{XO}}}{\mathrm{Rsh}}+\frac{{\mathrm{\φ}}^2{S_{\mathrm{XO}}}^2}{{\mathrm{aR}}_{\mathrm{mf}}(1-{\mathrm{Vsh}}^C)}$

$\mathrm{Sxo}=\frac{{\mathrm{\Φ}}_N-{\mathrm{\Φ}}_{\mathrm{Nma}}(1-\mathrm{\φ}-\mathrm{Vsh})-\mathrm{Vsh}{\mathrm{\Φ}}_{\mathrm{Nsh}}-\mathrm{\φ}{\mathrm{\Φ}}_{\mathrm{Ng}}}{\mathrm{\φ}({\mathrm{\Φ}}_{\mathrm{Nw}}-{\mathrm{\Φ}}_{\mathrm{Ng}})}$

In the formula: R _Xo, R _w, Rsh-is respectively shallow side direction (induction) resistivity, formation water resistivity and shale resistivity;

Φ _Ng, φ _Nw, Φ _Nma, Φ _Nsh-be respectively the neutron hydrogen content of rock gas, local water, rock skeleton and shale;

The Vsh-shale index;

A, C-experience factor often can be 1～2.

Formation resistivity R after shale is proofreaied and correct _cSatisfy following formula:

$\frac{1}{R_c}=\frac{1}{R_t}-\frac{\mathrm{Vcl}}{\mathrm{Rcl}}$

For for simplicity, the resistivity Rsh of the contiguous pure shale layer of also desirable reservoir is as the resistivity of the contained shale of reservoir, tries to achieve formation resistivity R after the correction with following formula again _c

2. get rid of the influence of factor of porosity to resistivity

Log well by the rock core scale, obtain reservoir accurately after factor of porosity, the water saturation data, utilize rock electricity experimental data to obtain the litho-electric parameters (cementation exponent m, saturation exponent n, lithology factor a and coefficient b) of reservoir, the resistivity data (R after the shale correction _c) the substitution Archie equation, try to achieve the resistivity value of each factor of porosity correspondence, by regretional analysis, proofread and correct the influence of factor of porosity to resistivity.

C, utilize core experiment to obtain the parameter of m, a, n, b reflection pore texture, calculate gas-bearing formation resistivity lower limit (RR), the evacuation aperture gap structure is to the influence of resistivity.

Utilize rock core to carry out the experiment of rock electricity and can obtain reflecting RESERVOIR PORE STRUCTURE and oil, gas, the litho-electric parameters of the distribution of water in hole: m (cementation exponent), n (saturation exponent), a (lithology factor), b (coefficient), utilize rock core phase permeability analysis of data to obtain the maximum water saturation data of reservoir, factor of porosity and resistivity data (Rc) the substitution Archie equation after shale is proofreaied and correct, obtained having eliminated lithology like this, the gas-bearing formation lower limit resistivity value of pore texture, by analyzing factor of porosity and this gas-bearing formation lower limit resistivity value, proofread and correct factor of porosity to resistivity effects on the one hand, in addition, recurrence draws the formula that calculates this resistivity value, calculates the continuous gas-bearing formation lower limit resistivity data (RR) identical with well-log information resolution in target well section.

Be the Su Lige gas field 8 sections gas-bearing formation lower limit resistivity value tables of having eliminated each factor of porosity correspondence of lithology and pore texture of 5 block boxes of reviving as: table one, Fig. 1 is factor of porosity and the gas-bearing formation lower limit resistivity relation figure that obtains from table one data, can be obtained the computing formula of gas-bearing formation lower limit resistivity (RR) by Fig. 1:

RR＝0.2834*Φ ^(-1.6755)

Table one Soviet Union's 8 sections factor of porosity of 5 block boxes and gas-bearing formation lower limit resistivity value mapping table

D, the big or small discrimination of reservoir fluid type by the gas-bearing formation lower limit resistivity value (RR) in deep induction (dark side direction) resistivity value (RT) and the c step.

Because the reflection of formation resistivity convection cell is responsive, gas-bearing formation (oil reservoir) resistivity value height, the water layer resistivity value is low, but is subjected to nonfluid factor affecting such as lithology, factor of porosity and pore texture simultaneously.Gas-bearing formation lower limit resistivity value (RR) only needs except nonfluid influence factors such as lithology, factor of porosity and pore textures, and has kept the responsive characteristic of resistivity data convection cell reflection, has promptly kept the Response Property of resistivity value convection cell.Theoretical and a large amount of formation testing result verification, the size of deep induction (dark side direction) resistivity value and gas-bearing formation lower limit resistivity value (RR), can differentiate gas-bearing formation and water layer according to difference, this difference is concrete data, so we can say that this method is with the digitizing of resistivity data convection cell Response Property.Concrete discrimination standard is:

Gas-bearing formation: RT-RR＞0;

Water layer: RT-RR＜0.

Because this method can pointwise be differentiated fluid type on depth section, can accurately determine aerogenesis and the particular location that produces water for air water with layer.

Deep induction (dark side direction) resistivity data is a kind of conventional logging data that obtains by well logging.This method of discrimination also adapts to oil reservoir in theory.

Claims (6)

1. adopt resistivity data to carry out the method for distinguishing reservoir fluid type, it is characterized in that step is as follows:

A, by rock core information scale well logging, accurately calculate reservoir shale index, rock composition and factor of porosity;

B, eliminating lithology and factor of porosity are to the influence of resistivity;

By the relation of each lithology of statistical study and resistivity, resistivity is carried out lithology proofread and correct;

By rock core scale well logging, obtain the factor of porosity, water saturation data of reservoir after, the resistivity data R after the lithology correction _cThe substitution Archie equation is tried to achieve the resistivity value of each factor of porosity correspondence, by regretional analysis, proofreaies and correct the influence of factor of porosity to resistivity;

C, utilize core experiment to obtain the parameter of m-cementation exponent, a-lithology factor, n-saturation exponent, b-coefficient reflection pore texture, calculate gas-bearing formation resistivity lower limit RR, the evacuation aperture gap structure is to the influence of resistivity;

Utilize rock core to carry out the litho-electric parameters that the experiment of rock electricity obtains reflecting RESERVOIR PORE STRUCTURE and oil, gas, the distribution of water in hole: m-cementation exponent, n-saturation exponent, a-lithology factor, b-coefficient, utilize rock core phase permeability analysis of data to obtain the maximum water saturation data of reservoir, again factor of porosity and the resistivity data R after lithology is proofreaied and correct _cThe substitution Archie equation, the gas-bearing formation lower limit resistivity value of lithology, pore texture has been eliminated, by analyzing factor of porosity and described gas-bearing formation lower limit resistivity value, proofread and correct factor of porosity to resistivity effects, also return and draw the formula that calculates this resistivity value, in target well section, calculate the continuous gas-bearing formation lower limit resistivity data RR identical with well-log information resolution;

D, by the big or small discrimination of reservoir fluid type of resulting gas-bearing formation lower limit resistivity value RR among deep induction-dark side direction resistivity value RT and the step C, specifically discrimination standard is:

Gas-bearing formation: RT-RR＞0;

Water layer: RT-RR＜0.

2. employing resistivity data according to claim 1 carries out the method for distinguishing reservoir fluid type, it is characterized in that:

The rock core information scale well logging concrete grammar of described steps A is as follows:

1. shale index is calculated in rock core information scale well logging

Determine clay type and clay property with rock core information, the analysis-by-synthesis well-log information, calculate logging trace, computing method and the processing parameter of shale index, and demarcate the shale index numerical value that well logging is calculated with core analysis shale index numerical value, fine setting shale processing parameter and disposal route, shale index and result of core analysis error minimum that well logging is calculated;

2. factor of porosity, permeability, water saturation and rock component content are calculated in rock core scale well logging

At first utilize X plot, histogram Mathematical Statistics Analysis method tentatively to determine interval transit time, neutron, density value and the fluid parameter of shale and skeleton, determine to calculate factor of porosity and rock composition according to the reservoir space characteristic, utilize core analysis factor of porosity data, lithification to analyze rock composition result again and demarcate factor of porosity and the rock component content that well logging is calculated, adjust shale correction parameter, mineral skeleton and fluid parameter, make logging data processing result and result of core analysis satisfy error requirements;

Utilize core analysis factor of porosity and permeability data to return and obtain hole infiltration relation calculating reservoir permeability, and demarcate well logging result of calculation with the core analysis permeability data;

Utilize the local water analysis of data to obtain formation water resistivity, utilize rock electricity experimental data to obtain reflecting RESERVOIR PORE STRUCTURE and oil, gas, the litho-electric parameters m-cementation exponent of the distribution of water in hole, n-saturation exponent, a-lithology factor, b-coefficient, calculate water saturation.

3. employing resistivity data according to claim 2 carries out the method for distinguishing reservoir fluid type, it is characterized in that: described rock core information is a rock core X diffraction analysis achievement.

4. employing resistivity data according to claim 2 carries out the method for distinguishing reservoir fluid type, it is characterized in that: described rock core information is the electron-microscope scanning analysis results.

5. employing resistivity data according to claim 2 carries out the method for distinguishing reservoir fluid type, it is characterized in that: the factor of porosity data is acoustic logging data or density data.

6. employing resistivity data according to claim 2 carries out the method for distinguishing reservoir fluid type, it is characterized in that:

When adopting the well logging of rock core information scale to calculate shale index,, adopt following two class methods to calculate for the high radioactivity stratum of natural gamma value:

One class: when the power spectrum data, analyze the kind and the character of non-shale radiomaterial in the stratum earlier, find out and shale radioactivity difference.According to clay type and clay property, select for use thorium, potassium, no uranium gamma to calculate shale index; Computing formula is:

$\mathrm{SH}=\frac{\mathrm{SPECT}-{\mathrm{SPECT}}_{\mathrm{nin}}}{{\mathrm{SPECT}}_{\max }-{\mathrm{SPECT}}_{\min }}$

$V_{\mathrm{SH}}=\frac{2^{\mathrm{GCUR}\×\mathrm{SH}}-1}{2^{\mathrm{GCUR}}-1}$

In the formula: V _SH-stratum shale index;

The SH-shale index;

SPECT, SPECT _Max, SPECT _MinBe respectively stratum gamma spectrometry log value, maximal value, minimum value;

Another kind of: as when not having the power spectrum data,, to calculate shale index with neutron data and factor of porosity data simultaneous owing to comprise total hydrogen index of water in the neutron data reaction stratum; When calculating shale index, select the factor of porosity data.The formula that neutron and density simultaneous calculate shale index is:

Φ _N＝φ _t(Φ _wS _w+Φ _hS _h)+Φ _shV _sh+Φ _ma(1-φ _t-V _sh)

ρ _b＝φ _t(ρ _wS _w+ρ _hS _h)+ρ _shV _sh+ρ _ma(1-φ _t-V _sh)

In the formula: Φ _N, φ _t, Φ _w, Φ _s, Φ _Sh, Φ _MaBe respectively total hydrogen index, factor of porosity, the hydrogen index of water, the hydrogen index of hydrocarbon, the hydrogen index of shale, the hydrogen index of rock skeleton;

ρ _b, ρ _w, ρ _h, ρ _Sh, ρ _MaBe respectively the density of gross density, water, the density of hydrocarbon, the density of shale, the density of rock skeleton;

S _w, S _h, V _ShBe respectively saturation degree, the shale index of water saturation, hydrocarbon.

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