CN105844011A - Capillary model-based permeability computing method - Google Patents

Abstract

The invention discloses a capillary model-based permeability computing method. The method comprises the following steps: firstly, carrying out a physical property experiment and a rock electricity experiment on a rock core to obtain core porosity, core permeability, core lithology factor and cementation index; computing the pore-throat diameter ratio and the throat diameter and confirming the throat diameter of the corresponding rock core through combining with the result of the rock physical experiment and by utilizing a permeability analytical model derived on the basis of a capillary model; fitting the relations between a well-logging curve and the core porosity as well as between the well-logging curve and the core throat diameter through a least square method and computing the core porosity and the core throat diameter through the well-logging curve; and computing the reservoir permeability by utilizing the permeability analytical model. According to the permeability theoretical computing model built in the invention, rock electricity parameters are introduced into a pore throat computing structure; the permeability is computed on the basis of the computation of the porosity, the pore-throat diameter ratio and the throat diameter; the macroscopic physical quantity is reflected by microscale; and therefore, the reservoir permeability can be accurately and reliably computed and reliable reservoir parameters are provided for petroleum reservoir exploitation and evaluation.

Description

A kind of calculation of permeability based on capillary model

Technical field

The present invention relates to evaluating reservoir field, particularly to a kind of computational methods determining reservoir permeability.

Background technology

Reservoir permeability is to weigh fluid under pressure differential by a kind of amount of porous rock active porosity ability Value, accurately asks for the element task that reservoir permeability is evaluating reservoir.

Straight parallel capillary model is derivation reservoir permeability and the most typical model of microscopic void parameter, and it is set up Permeability with the relation of porosity is:

In formula: k is reservoir permeability；R is straight parallel capillary radius；For porosity.Parallel capillary model The permeability theoretical model set up does not considers that the impact of structure is shouted in hole, shouts structure with actual rock core hole and differs relatively big, Can not effectively reflect that the relation between structure is shouted in reservoir permeability and hole.

Relation between permeability and microscopic void parameter that series connection capillary model is set up is:

$k=\frac{n_0{\mathrm{\πl}}_e{D}_s^4}{128l_s(1+\frac{D_s^4{l}_l}{D_l^4{l}_s})}---\left(2\right)$

In formula: k is reservoir permeability；D_lFor elementary cell hole footpath；D_sFor elementary cell throat diameter； l_lFor elementary cell length；l_sFor elementary cell pore length；l_eLength, l is shouted for elementary cell hole_e=l_l+l_s； n₀For the series connection capillary number on unit area.

Series connection capillary model can the hole in simulated formation micropore structure and throat effectively, hole is shouted Structural parameters are incorporated in computing permeability, but there is the parameter that cannot determine in a large number in formula, do not derive The determination method of micro-parameter, it is impossible to carry out actual application.

The models treated such as other model such as networking model, percolation model, model suspending are got up excessively complicated, nothing Method sets up the theoretical model between permeability and micro-parameter, it is difficult to carry out parameter calculating.

Summary of the invention

The technical problem to be solved is to provide a kind of calculation of permeability based on capillary model, Be capable of obtaining quantitative, continuous print by rock-electric test parameter, porosity, structure is shouted in high-precision hole Parameter, makes calculated permeability more accurate.

For solving above-mentioned technical problem, the invention provides a kind of calculation of permeability based on capillary model, Step includes:

Choose the Sandstone Cores of size fractionated, obtain including rock by rock core physical property and rock core rock-electric test measurement The core experiment data of central hole porosity, permeability, lithology factor a and cementation factor m；Utilize series connection hollow billet mould Permeability set up respectively by type, hole is shouted diameter and shouted with permeability and hole than theoretical calculation model, Binding experiment data Diameter ratio, throat diameter are shouted in the hole that diameter calculates rock core micropore structure than theoretical calculation model；By Little square law matching throat diameter and well logging relation between gamma ray curve, porosity, set up based on survey The throat diameter computation model of well data, it is achieved log is to the conversion of throat diameter；Finally, will calculate Lithology factor a, cementation factor m that porosity, throat diameter and the experiment obtained obtains are updated to permeability reason Opinion computation model calculates reservoir permeability.

Further, described rock core physical property experiment is according to " core analysis method SY/T 5336-2006 " standard gauge Fixed flow process is carried out.

Further, described rock core rock-electric test is according to " core analysis method SY/T 5336-2006 " standard gauge Fixed flow process is carried out.

Further, described permeability theoretical calculation model is as follows:

In formula, k is reservoir permeability；D_sFor throat diameter；For porosity；δ is that diameter ratio is shouted in hole.

Permeability is the function that the micro-parameters such as diameter ratio, throat diameter are shouted in porosity, hole, can more preferable earth's surface Reach the physical influence factor of permeability.

Further, described hole is shouted diameter and is included than theoretical calculation formula and meaning:

In formula: δ is that diameter ratio is shouted in hole；For porosity；A is lithology factor；M is cementation factor.Pass through Above formula determines hole and shouts the analytic solutions of diameter, and it is the function of porosity and litho-electric parameters.

Diameter ratio, the determination of throat diameter are shouted in the hole of rock core micropore structure, be rock core measured hole porosity, On the basis of permeability, litho-electric parameters a, m, shout diameter and carry out inverse in conjunction with permeability, hole than theoretical model.

Further, utilize throat diameter and well logging to there is dependency between gamma ray curve, porosity, build The throat diameter computation model of vertical well-log information:

$\mathrm{\Δ}GR=\frac{GR-{\mathrm{GR}}_{min}}{{\mathrm{GR}}_{max}-{\mathrm{GR}}_{min}}---\left(4\right)$

In formula, D_sFor throat diameter；Δ GR is natural gamma relative value；GR is gamma ray log value；GR_min For clean sandstone gamma ray log value；GR_maxFor pure shale section gamma ray log value；For porosity；A、 B, C are model coefficient, by core experiment data and log data, use least square fitting to obtain.

Further, during for there is no core experiment data, can be obtained by log data fitting empirical formula Throat diameter D_s；Wherein, porosity is calculated by regional experience formula.

Further, the formula asking for permeability is as follows:

Wherein, throat diameter D_sObtained by the empirical equation of matching by log data；PorosityBase area District's empirical equation utilizes tri-porosity logging data to obtain；Hole is shouted diameter and is calculated with litho-electric parameters by porosity than δ Obtain.

Present invention is characterized in that

The permeability theoretical calculation model that the present invention sets up, is incorporated into calculating hole litho-electric parameters and shouts in structure, On the basis of diameter ratio, the calculating of throat diameter are shouted in porosity, hole, calculate permeability, reflect from micro-scale Macroscopic physical quantity；Utilize the permeability concordance that the calculated permeability of the inventive method and experiment are measured relatively Good, it is possible to permeability accurate, calculating reservoir reliably, provide reliable reservoir ginseng for oil reservoir development evaluation Number.

Accompanying drawing explanation

For the technical scheme being illustrated more clearly that in the embodiment of the present invention, institute in embodiment being described below The accompanying drawing used is needed to be briefly described.

Fig. 1 is the method flow diagram of the determination reservoir permeability that the embodiment of the present invention provides；

Fig. 2 (a) Fig. 2 (b) is the series connection capillary model schematic diagram that the embodiment of the present invention provides；

Fig. 3 is formation factor and the porosity graph of a relation of embodiment of the present invention offer；

Fig. 4 (a), (b) are respectively throat diameter and porosity linear relationship chart, throat diameter and natural gamma Relative value's logarithmic relationship figure；

Fig. 5 is the computing permeability result map that the embodiment of the present invention provides；

Fig. 6 is core permeability and the calculating permeability concordance comparison diagram of embodiment of the present invention offer.

Detailed description of the invention

Below in conjunction with specific embodiment, the present invention is described in further detail, described in the present invention Explain rather than limit.

Seeing Fig. 1, the calculation of permeability based on capillary model that the embodiment of the present invention provides, including as follows Step:

Step 101: choose the Sandstone Cores of size fractionated, according to " core analysis method SY/T 5336-2006 " The flow process that standard specifies carries out rock core physical property and rock core rock-electric test, measures and obtains including core porosity, oozing Rate, lithology factor a and the core experiment data of cementation factor m thoroughly.

Step 102: utilize series connection capillary model, set up permeability respectively, hole is shouted diameter and compared theoretical calculation model；

Permeability theoretical calculation model:

In formula, k is reservoir permeability；D_sFor throat diameter；For porosity；δ is that diameter ratio is shouted in hole.

Diameter is shouted than theoretical calculation model in hole:

In formula, δ is that diameter ratio is shouted in hole；D_lFor pore diameter；D_sFor throat diameter；A is lithology factor；m For cementation factor；For porosity.

Step 103: utilize core experiment data: core porosity, permeability, litho-electric parameters (lithology factor A and cementation factor m) combine permeability, diameter is shouted than theoretical model in hole, calculates reflection rock core microscopic void knot Diameter ratio, throat diameter are shouted in the hole of structure.

Step 104: by least square fitting rock core throat diameter and well logging gamma ray curve, porosity Between relation, set up throat diameter computation model based on well-log information；Porosity is by regional experience formula Calculate；

Throat diameter computation model based on well-log information is as follows:

$\mathrm{\Δ}GR=\frac{GR-{\mathrm{GR}}_{min}}{{\mathrm{GR}}_{max}-{\mathrm{GR}}_{min}}---\left(4\right)$

In formula, D_sFor throat diameter；Δ GR is natural gamma relative value；GR is gamma ray log value；GR_min For clean sandstone gamma ray log value；GR_maxFor pure shale section gamma ray log value；For porosity；A、 B, C are model coefficient, by core experiment data and log data, use least square fitting to obtain.

Step 105: by experiment lithology factor a, cementation factor m and the porosity of calculatingThroat diameter D_s Be updated in permeability theoretical calculation model calculate reservoir permeability k:

Below, it is described in further details by the present embodiment is embodied as situation, to support the present invention Technical problem to be solved.

1, select a certain goals research block, choose the Sandstone Cores of different gravel level, according to " core analysis side Method (SY/T5336-2006) " normal process test, measure core porosity, permeability, lithology system Number a and cementation factor m, prepare data for follow-up Experimental modeling.

2, series connection capillary model is utilized, such as Fig. 2 (a) matrix pores series connection capillary model and Fig. 2 (b) string Shown in connection hollow billet elementary cell, set up permeability respectively, diameter is shouted than theoretical calculation model in hole:

In formula, k is reservoir permeability；For porosity；δ is that diameter ratio is shouted in hole；D_sFor throat diameter；A is Lithology factor；M is cementation factor.

3, rock-electric test porosity and formation factor relation are utilized, as it is shown on figure 3, determine lithology system respectively Number a=0.9182, cementation factor m=1.7532.

4, utilize core experiment porosity, permeability, litho-electric parameters to combine permeability, diameter is shouted than theory in hole Model, diameter ratio, throat diameter are shouted in the hole calculating reflection rock core micropore structure.

5, utilize rock core throat diameter and well logging to there is dependency between gamma ray curve, porosity, set up Throat diameter computation model based on well-log information；Fig. 4 (a), (b) are respectively throat diameter and porosity line Sexual relationship figure, throat diameter and natural gamma relative value's logarithmic relationship figure.Can see from figure and have between them Preferably dependency.Therefore, utilize method of least square to carry out multiparameter modeling and determine throat diameter computation model. In this example, D_sThe fit correlation formula of value is:

6, in-place permeability is calculated.The formula asking for permeability is as follows:

Wherein, throat diameter D_sThe empirical equation utilizing log data matching obtains；Porosity is according to area warp Test formulaCalculate and obtain；Diameter is shouted than δ by porosity and litho-electric parameters meter in hole Obtain.Fig. 5 is computing permeability result map, utilizes the calculated permeability of the inventive method and experiment The permeability concordance measured is preferable.From fig. 6 it can be seen that the reservoir infiltration that the embodiment of the present invention provides Rate and core experiment permeability are near 45 degree of lines, and the two concordance is fine, illustrates that the embodiment of the present invention provides The method of determination reservoir permeability can determine reservoir permeability accurately, reliably.

It should be noted last that, above detailed description of the invention only in order to technical scheme to be described rather than Limiting, although being described in detail the present invention with reference to example, those of ordinary skill in the art should manage Solve, technical scheme can be modified or equivalent, without deviating from the technology of the present invention side The spirit and scope of case, it all should be contained in the middle of scope of the presently claimed invention.

Claims (7)

1. a calculation of permeability based on capillary model, it is characterised in that follow the steps below Operation:

1) choose the Sandstone Cores of size fractionated, carry out rock core physical property and rock core rock-electric test, measure and wrapped Include the core experiment data of core porosity, permeability, lithology factor a and cementation factor m；

2) utilize series connection capillary model, set up permeability respectively and hole is shouted diameter and compared theoretical calculation model；

3) core experiment data and permeability and hole is utilized to shout diameter more micro-than theoretical calculation model calculating reflection rock core Diameter ratio and throat diameter are shouted in the hole of view hole gap structure；

4) relation between gamma ray curve, porosity by least square fitting throat diameter and well logging, Set up throat diameter computation model based on well-log information；

5) willCalculatedPorosity, throat diameter with experiment obtain lithology factor a, cementation factor m It is updated in permeability theoretical calculation model calculate reservoir permeability.

2. the method for claim 1, it is characterised in that described rock core physical property experiment is according to " rock core Analysis method SY/T 5336-2006 " flow process that specifies of standard carries out.

3. the method for claim 1, it is characterised in that described rock core rock-electric test is according to " rock core Analysis method SY/T 5336-2006 " flow process that specifies of standard carries out.

4. the method for claim 1, it is characterised in that described permeability theoretical calculation model is as follows:

In formula, k is reservoir permeability；D_sFor throat diameter；For porosity；δ is that diameter ratio is shouted in hole.

5. the method for claim 1, it is characterised in that described hole is shouted diameter and compared theoretical calculation model As follows:

In formula, δ is that diameter ratio is shouted in hole；D_lFor pore diameter；D_sFor throat diameter；A is lithology factor；m For cementation factor；For porosity.

Method the most according to claim 1, it is characterised in that step 4) in, set up based on well logging The throat diameter computation model of data is as follows:

$\mathrm{\Δ}GR=\frac{GR-{\mathrm{GR}}_{min}}{{\mathrm{GR}}_{max}-{\mathrm{GR}}_{min}}---\left(4\right)$

In formula, D_sFor throat diameter；Δ GR is natural gamma relative value；GR is gamma ray log value；GR_min For clean sandstone gamma ray log value；GR_maxFor pure shale section gamma ray log value；For porosity；A、 B, C are model coefficient, by core experiment data and log data, use least square fitting to obtain.

Method the most according to claim 1, it is characterised in that the formula asking for reservoir permeability is as follows:

Wherein, k is reservoir permeability；Obtain by tri-porosity logging data for porosity；Diameter ratio is shouted in hole δ is calculated with litho-electric parameters by porosity.