CN103543474A - Hydrocarbon saturation evaluation method based on non-conductive pore model - Google Patents

Abstract

The invention provides a hydrocarbon saturation evaluation method based on a non-conductive pore model, and belongs to the field of oil-gas exploration and development. The method includes determining non-conductive porosity in a stratum and the ratio in the total porosity according to rock physical experiments, and utilizing an evaluating equation based on the non-conductive pore hydrocarbon saturation to determine the hydrocarbon saturation of a reservoir stratum. The method is effective to complex reservoir stratum, which is not adaptable to the traditional Archie theory, hydrocarbon saturation quantifying evaluation; lithological background conductivity factors are taken into account, and the method is particularly adaptable to the reservoir stratum which has large changes in lithology and strong heterogeneity; the method is adaptable to hydrocarbon saturation evaluation of complex reservoir stratums of various volcanic rocks, fractured carbonate rocks, metamorphosed rocks and the like, and reliable technique support is provided for efficient exploration and development of complex oil and gas reservoirs.

Description

A kind of hydrocarbon saturation evaluation method based on non-conductive pore model

Technical field

The invention belongs to oil-gas exploration and development field, be specifically related to a kind of hydrocarbon saturation evaluation method based on non-conductive pore model.

Background technology

Utilizing well-log information to determine that in reservoir, hydrocarbon saturation is the basis of Efficient Exploration and development of fields, is also the core of Logging Evaluation of Fractured Reservoir.As far back as nineteen forty-two, Mr. A Erqi (the oil well logging slip-stick artist of Shell Co. Ltd) has delivered famous Archie equation, establish the basis of hydrocarbon saturation quantitative evaluation, in actual production, be used widely, remain at present the main stream approach of well logging hydrocarbon saturation quantitative evaluation.Tradition A Erqi theory is suitable for take primary interparticle pore as the main and factor of porosity clean sandstone reservoir of large (being generally greater than 15%).For this class reservoir, theoretical according to A Erqi, utilize well-log information to determine that hydrocarbon saturation precision is very high, its application has obtained the extensive approval of petroleum industrial circle, and this class reservoir is called A Erqi reservoir.Tradition A Erqi theory is the theoretical foundation of hydrocarbon saturation quantitative evaluation.But, in recent years, along with oil-gas exploration and development field deepen continuously and oil-gas exploration and development object day by day complicated, there is a large amount of seam hole type carbonatite, volcanics, Metamorphic Reservoirs, fractured mudstone reservoir even, the limitation of A Erqi theory also embodies.This class Reservoir Body reservoir space type is complicated, and nonuniformity is strong, electrical conduction mechanism is obviously different from A Erqi reservoir, manifest " Fei Aerqiization " phenomenon, if directly apply mechanically Archie equation for this class reservoir, carry out hydrocarbon saturation evaluation, will bring very large error, or even wrong conclusion.

At present to " Fei Aerqiization " complicated reservoirs hydrocarbon saturation Logging Evaluation Method also in constantly exploring, main method is for complicated reservoirs feature, and key parameter in A Erqi theory is revised, and is then applied to the evaluation of reservoir hydrocarbon saturation.The concrete practice is divided three classes:

One, research affects key parameter in Archie equation (being mainly cementation exponent m and saturation exponent) geologic agent, on experiment basis or with individual regional experience, these key parameters are quantized to revise, then apply Archie equation and determine reservoir hydrocarbon saturation, Ru Li army, Zhang Chaomo etc. (2009) are in storehouse car area complicated reservoirs hydrocarbon saturation is evaluated, utilize experimental data, determine m exponential sum n index quantitative relationship, revise Archie equation; Wang Qing ,Li state equality (2003), in the research of complicated reservoir well logging interpretation, employing experience estimation m, n index method are revised A Erqi theory.

They are two years old, according to multi-pore media electrical conduction model, derive and digital simulation calculating, based on this A Erqi theory is revised, as proposing, (2006) such as Pan Baozhi, Zhang Lihua form three pore models by matrix, crack and non-intercommunicating pore hole, according in parallel and series connection conductivity principle, derive the m exponential expression under different aperture array configuration, on this basis traditional A Erqi theory is revised.

They are three years old, under certain assumed condition, according to conductive network parallel conductance principle, in conjunction with A Erqi, theoretical and electric logging response feature, derives and obtains hydrocarbon saturation evaluation equation, as (2005) such as Zhao Liangxiao, Zhang Shudong, in carbonate complex rock saturation degree is evaluated, base area layer fluid is different existence state and resistivity logging response characteristic in ,Dong He crack, hole, utilizes parallel conductance principle, and theoretical in conjunction with A Erqi, a kind of hydrocarbon saturation evaluation method is proposed.

Obviously, these methods, with regard to essence, do not depart from the framework category of A Erqi theory, and hydrocarbon saturation evaluation precision is difficult to hold, and in actual mechanical process or with personal experience, randomness is larger; Or operation is too complicated, is difficult to promote the use of.And should see, A Erqi theory has application conditions restriction, the reservoir that contains a large amount of isolated pores for those and reservoir space be the reservoir of inhomogeneous distribution extremely, does not meet essentially the theoretical application conditions of A Erqi, also just can not revise it.

From electric conductivity, hole is divided into conduction hole and non-conductive hole, and the basic reason of reservoir " Fei Aerqiization " is that the non-conductive distribution of pores form of complicated reservoirs is different from traditional A Erqi reservoir, thereby causes the inadaptability of A Erqi theory.

Summary of the invention

The object of the invention is to solve the difficult problem existing in above-mentioned prior art, a kind of hydrocarbon saturation evaluation method based on non-conductive pore model is provided, it is for complicated reservoirs " Fei Aerqiization " phenomenon, take Maxwell's equation conductivity theory as design experimental technique and flow process, measure non-conductive hole, determine on this basis hydrocarbon saturation.

The present invention is achieved by the following technical solutions:

A kind of hydrocarbon saturation evaluation method based on non-conductive pore model, first described method according to the ratio of non-conductive factor of porosity and shared total porosity thereof in the definite stratum of rock physics experiment, then utilizes the hydrocarbon saturation of determining reservoir based on non-conductive hole hydrocarbon saturation evaluation equation.

Said method comprising the steps of:

(1) utilize density logging data and neutron well logging data intersection calculation to obtain the physics total porosity φ of reservoir _t;

(2) reservoir pore space is divided into conduction hole and non-conductive hole: calling by the hole of electric current conduction hole in reservoir pore space, not calling by the hole of electric current non-conductive hole;

(3) be determined by experiment non-conductive factor of porosity φ _sand with total porosity φ _tratio;

(4) determine the hydrocarbon saturation of reservoir.

Described step (3) is specific as follows:

By rock physics, test, determine the physics total porosity φ of reservoir _twith formation resistivity factor F _r, then by Experiment Data Records with total porosity φ _tfor the longitudinal axis (Y-axis), with on figure for transverse axis (X-axis), the described experimental data in figure is carried out to matching and obtain regression straight line, described regression straight line and the longitudinal axis intersect, and the intercept of regression straight line on the longitudinal axis is described non-conductive factor of porosity φ _s; Finally calculate non-conductive factor of porosity φ _swith total porosity φ _tratio R _i:

$R_i=\frac{{\mathrm{\φ}}_s}{{\mathrm{\φ}}_t}.$

Described step (4) is specific as follows:

Utilize below based on non-conductive hole hydrocarbon saturation evaluation equation, determine water saturation S _wwith hydrocarbon saturation S _hr:

$S_w=\frac{-B+\sqrt{B^2-4\mathrm{AC}}}{2A}$

S _hr＝1.0-S _w

In formula: A=C _w

B＝-(C _wR _i+C _BG)

$C=C_{\mathrm{BG}}{R}_i-\frac{a(C_{\mathrm{Log}}-C_{\mathrm{BG}})}{{\mathrm{\φ}}_t}$

C _wfor stratum electrical conductivity of water, C _bGfor background conductance rate, C _logfor well logging conductivity, the percent continuity that α is pore space;

The obtaining value method of α is as follows: in water layer section, read conductivity C _log, be designated as C _log100:

$a=\frac{(C_w-C_{\mathrm{BG}})(1-R_i)}{(C_{\mathrm{Log}100}-C_{\mathrm{BG}})}{\mathrm{\φ}}_t.$

Compared with prior art, the invention has the beneficial effects as follows:

(1) enrich with develop of the present invention hydrocarbon saturation evaluation theory, for being unsuitable for the complicated reservoirs hydrocarbon saturation quantitative evaluation of traditional A Erqi theory, provide effective method;

(2) in the inventive method, consider lithology background conduction factor, be therefore also particularly suitable for the reservoir that lithological change is large and nonuniformity is strong;

(3) the inventive method strong adaptability, can be applicable to the complicated reservoirs hydrocarbon saturation evaluations such as all kinds of volcanics, seam hole type carbonatite and metamorphosed rock, develops this class complex reservoir robust techniques support is provided for Efficient Exploration.

Accompanying drawing explanation

Fig. 1 is the step block diagram that the present invention is based on the hydrocarbon saturation evaluation method of non-conductive pore model.

Fig. 2 is the non-conductive factor of porosity figure that the present invention is based on the reservoir samples that in the hydrocarbon saturation evaluation method of non-conductive pore model, experiment obtains.

Fig. 3 is the Metamorphic Reservoirs logging data processing result map in the embodiment of the present invention one.

Fig. 4 is the carbonate reservoir logging data processing result map in the embodiment of the present invention two.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail:

The present invention has abandoned traditional A Erqi saturation degree evaluation theory, from electrical angle, complicated reservoirs reservoir space is marked off to conduction hole and non-conductive hole, take Maxwell's equation conductivity theory as guidance, design a set of experimental technique and flow process, determine non-conductive hole and ratio thereof in reservoir, propose on this basis hydrocarbon saturation Slope map of pixels.As shown in Figure 1, a kind of hydrocarbon saturation evaluation method based on non-conductive pore model comprises the following steps:

(1) input well logging raw data (comprising porosity log data and Electric Log Data), stratum electrical conductivity of water C _w, tight zone stratum background resistivity C _bG;

(2) obtain stratum total porosity φ _tand non-conductive factor of porosity φ is determined in experiment _s:

In general, serve as the rock skeleton of oil and gas reservoir by nonconducting mineral composition, the conductive capability of rock depends on blowhole and fluid conductive capability wherein.Calling conduction hole by the part hole of electric current in reservoir pore space, can not be called by the hole of electric current non-conductive hole, as the bay shape part of isolated pore, corrosion expandable pores etc.

If the total porosity of formation rock is φ _t, non-conductive factor of porosity is φ _s, formation resistivity factor is F _r, theoretical according to Maxwell's equation, through deriving, set up and determine non-conductive factor of porosity φ _smethod.

Derivation is as follows:

Ideally (between non-conductive, mutually do not contact) formation resistivity factor (F _r) and formation porosity (φ _t) relation meet Maxwell's equation equation:

$F_r=\frac{3-{\mathrm{\&phi;}}_{\mathrm{<figure-callout\; id="2"\; label="t"\; filenames="DEST\_PATH\_HDA00002766309700021.png"\; state="\{\{state\}\}">t</figure-callout>}}}{2{\mathrm{\&phi;}}_t}---\left(2\right)$

Turn to equation is general:

$F_r=\frac{(x+1)-{\mathrm{\&phi;}}_t}{x{\mathrm{\&phi;}}_t}=1+\frac{G(1-{\mathrm{\&phi;}}_t)}{{\mathrm{\&phi;}}_t}---\left(3\right)$

$G=\frac{1+x}{x}$

In formula: x is a geometric parameter, relevant with particle shape.

(3) formula of disperseing spherolite system to follow is modified as to formula below:

$F_r=1+\frac{G(1-{\mathrm{\&phi;}}_f)}{{\mathrm{\&phi;}}_f}---\left(4\right)$

In formula: φ _fbe called conduction factor of porosity.

Above formula is implying in the irregular Complex Rock system of pore wall, and total porosity is divided into conduction factor of porosity φ _fwith non-conductive factor of porosity φ _s, that is:

φ _t＝φ _f+φ _s (5)

The pass of supposing conduction factor of porosity and total porosity is:

φ _f＝C ₁φ _t+C ₂ (6)

CONSIDERING BOUNDARY CONDITIONS:

When φ is reduced to a certain cutoff porosity φ _stime, flowing of electric current can be ignored, and works as φ that is: _t=φ _stime, φ _f=0; In addition, work as φ _t=1 o'clock, φ _f=1.

To in boundary condition substitution (6), obtain:

$C_1=\frac{1}{1-{\mathrm{\&phi;}}_s},$ ${\mathrm{<figure-callout\; id="2"\; label="C"\; filenames="DEST\_PATH\_HDA00002766309700021.png"\; state="\{\{state\}\}">C</figure-callout>}}_2=-\frac{{\mathrm{\&phi;}}_s}{1-{\mathrm{\&phi;}}_s}$

${\mathrm{\&phi;}}_f=\frac{{\mathrm{\&phi;}}_t-{\mathrm{\&phi;}}_s}{1-{\mathrm{\&phi;}}_s}---\left(7\right)$

(7) substitution (4) abbreviation is had:

${\mathrm{\&phi;}}_t={\mathrm{\&phi;}}_s+G\frac{(1-{\mathrm{\&phi;}}_t)}{F_R-1}---\left(8\right)$

Formula (8) is exactly the theoretical foundation that non-conductive hole is determined in experiment.In formula, G is geometric constant, relevant with pore shape.

One of key content of the present invention is exactly to determine non-conductive hole.First by rock physics, test and obtain experimental data, comprise total porosity φ _twith formation resistivity factor F _r, then utilize 2 pairs of experimental datas of accompanying drawing to arrange the non-conductive factor of porosity that can obtain rock reservoir.Wherein, F _rfor formation resistivity factor.

Experimental data is carried out to (longitudinal axis (y) is factor of porosity φ as Fig. 2 _t, transverse axis (x) is ) arrangement, experimental data is done

graph of a relation, then makes regression straight line (being the straight line that fitting formula is corresponding) and intersects with y axle, and the intercept of straight line on y axle is non-conductive hole φ _s, the slope of straight line is G.For example, obtain by experiment the data of 4 samples, in Fig. 2, shown four samples

relation (being 4 points in Fig. 2), obtains fitting formula and is:

${\mathrm{\&phi;}}_t=0.0125+24.7316\frac{1-{\mathrm{\&phi;}}_t}{F_r-1}---\left(9\right)$

Thereby obtain φ _s=0.0125, G=24.7, this numerical value is the example obtaining for those 4 points, to different regions, the value of these two parameters is different.

(3) by stratum total porosity φ _twith non-conductive factor of porosity φ _sobtain non-conductive hole and total porosity ratio R _i;

(4) determine percent continuity α;

(5) calculate water saturation S _wwith calculating oil saturation S _hr;

(6) the water saturation S that output step (5) obtains _wwith oil saturation S _hr.

Step (4) and step (5) are specific as follows:

In theory, resistivity logging only reflects that the electricity of the conduction hole of connection leads ability, but practical logging is the result of pore fluid, moisture microporosity, conductive mineral and pit shaft shunting action etc.Outside definite division pore fluid conduction, the resistivity that other factors causes is background resistivity, uses symbol R _bGrepresent, meanwhile, there is following boundary condition:

If 1. well logging conductivity equals background conductance rate, interconnected porosity is 0;

If the factor of porosity being 2. communicated with is 1, is hole entirely, the conductivity of measuring is electrical conductivity of water;

3. conductivity has the sumproperties in parallel of linear, additive.

Condition 1., 2. condition be formula (10) prerequisite, and 3. condition is used when derivation formula (11).

According to these conditions, can be communicated with conduction factor of porosity φ _frelational expression is as follows:

${\mathrm{\&phi;}}_f=\frac{C_{\mathrm{Log}}-C_{\mathrm{BG}}}{C_f-C_{\mathrm{BG}}}---\left(10\right)$

In formula, C _ffor the fluid conductivity in open pore, (conductivity of hydrocarbon is C _o, electrical conductivity of water is C _w), C _logfor well logging conductivity.

Further derivation can obtain based on non-conductive hole hydrocarbon saturation evaluation equation, namely water saturation (S _w) and hydrocarbon saturation (S _hr) equation:

$S_w=\frac{-B+\sqrt{B^2-4\mathrm{AC}}}{2A}---\left(11\right)$

S _hr＝1.0-S _w

In formula,

A＝C _w

B＝-(C _wR _i+C _BG)

$C=C_{\mathrm{BG}}{R}_i-\frac{a(C_{\mathrm{Log}}-C_{\mathrm{BG}})}{{\mathrm{\&phi;}}_t}$

$R_i=\frac{{\mathrm{\&phi;}}_s}{{\mathrm{\&phi;}}_t}$

C _wfor stratum electrical conductivity of water, C _bGfor background conductance rate (corresponding pure hydrocarbon zone, or the maximum resistivity value of tight zone), C _logfor well logging conductivity, φ _tfor total porosity, φ _sfor non-conductive factor of porosity, R _ifor non-conductive hole and total pore space ratio;

α is the percent continuity of pore space.The obtaining value method of α is as follows: in water layer section, read conductivity C _log, be designated as C _log100:

$a=\frac{(C_w-C_{\mathrm{BG}})(1-R_i)}{(C_{\mathrm{Log}100}-C_{\mathrm{BG}})}{\mathrm{\&phi;}}_t---\left(12\right)$

In order to verify that the inventive method is to the adaptability of complicated reservoirs and validity, the inventive method is applied to respectively to metamorphosed rock and the carbonate reservoir of lithology and reservoir space type complexity, and contrasts with result of core analysis, specific embodiment is as follows:

Embodiment mono-:

Utilize the inventive method to calculating from certain basin Metamorphic Reservoirs hydrocarbon saturation, its result is as shown in the dotted line in the saturation degree road in Fig. 3, as shown in the solid line in the saturation degree road of the hydrocarbon saturation obtaining of pressing mercury analysis by rock core in Fig. 3, contrast two curves and can find out that both are very approaching, this shows that the inventive method is applied in the validity in Metamorphic Reservoirs.

Embodiment bis-

Application the inventive method is processed the carbonate reservoir well-log information in another gas field, basin, the hydrocarbon saturation (being the calculating water saturation in Fig. 4) as shown in the solid line of last row in Fig. 4 that adopts the inventive method to calculate, the result of measuring by rock core is as shown in the round dot in last row in Fig. 4, relatively both can find out that both are very approaching, and this explanation the inventive method is also effective to carbonate reservoir.

The inventive method is applicable to the reservoir oil-gas possibility quantitative evaluation of complicated pore media system, comprises the complicated reservoirs such as all kinds of volcanics, seam hole type carbonatite and metamorphosed rock.The inventive method enrich with develop the quantitative evaluation of complicated reservoirs oily theoretical, in process of complex reservoir exploration exploitation, there is the wide application prospect of sending out.

Technique scheme is one embodiment of the present invention, for those skilled in the art, the invention discloses on the basis of application process and principle, be easy to make various types of improvement or distortion, and be not limited only to the described method of the above-mentioned embodiment of the present invention, therefore previously described mode is just preferred, and does not have restrictive meaning.

Claims (4)

1. the hydrocarbon saturation evaluation method based on non-conductive pore model, it is characterized in that: first described method according to the ratio of non-conductive factor of porosity and shared total porosity thereof in the definite stratum of rock physics experiment, then utilizes the hydrocarbon saturation of determining reservoir based on non-conductive hole hydrocarbon saturation evaluation equation.

2. the hydrocarbon saturation evaluation method based on non-conductive pore model according to claim 1, is characterized in that: said method comprising the steps of:

(1) utilize density logging data and neutron well logging data intersection calculation to obtain the physics total porosity φ of reservoir _t;

(2) reservoir pore space is divided into conduction hole and non-conductive hole: calling by the hole of electric current conduction hole in reservoir pore space, not calling by the hole of electric current non-conductive hole;

(3) be determined by experiment non-conductive factor of porosity φ _sand with total porosity φ _tratio R _i;

(4) determine the hydrocarbon saturation of reservoir.

3. the hydrocarbon saturation evaluation method based on non-conductive pore model according to claim 2, is characterized in that: said method comprising the steps of: described step (3) is specific as follows:

By rock physics, test, determine the physics total porosity φ of reservoir _twith formation resistivity factor F _r, then by Experiment Data Records with total porosity φ _tfor the longitudinal axis, with on figure for transverse axis, the described experimental data in figure is carried out to matching and obtain regression straight line, described regression straight line and the longitudinal axis intersect, and the intercept of regression straight line on the longitudinal axis is described non-conductive factor of porosity φ _s; Finally calculate non-conductive factor of porosity φ _swith total porosity φ _tratio R _i:

$R_i=\frac{{\mathrm{\&phi;}}_s}{{\mathrm{\&phi;}}_t}.$

4. the hydrocarbon saturation evaluation method based on non-conductive pore model according to claim 2, is characterized in that: described step (4) is specific as follows:

Utilize below based on non-conductive hole hydrocarbon saturation evaluation equation, determine water saturation S _wwith hydrocarbon saturation S _hr:

$S_w=\frac{-B+\sqrt{B^2-4\mathrm{AC}}}{2A}$

S _hr＝1.0-S _w

In formula: A=C _w

B＝-(C _wR _i+C _BG)

$C=C_{\mathrm{BG}}{R}_i-\frac{a(C_{\mathrm{Log}}-C_{\mathrm{BG}})}{{\mathrm{\&phi;}}_t}$

C _wfor stratum electrical conductivity of water, C _bGfor background conductance rate, C _logfor well logging conductivity, the percent continuity that α is pore space;

The obtaining value method of α is as follows: in water layer section, read conductivity C _log, be designated as C _log100:

$a=\frac{(C_w-C_{\mathrm{BG}})(1-R_i)}{(C_{\mathrm{Log}100}-C_{\mathrm{BG}})}{\mathrm{\&phi;}}_t.$

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