CN105205296A - Method for calculating porosity of shale gas reservoir - Google Patents

Method for calculating porosity of shale gas reservoir Download PDF

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Publication number
CN105205296A
CN105205296A CN201410253067.6A CN201410253067A CN105205296A CN 105205296 A CN105205296 A CN 105205296A CN 201410253067 A CN201410253067 A CN 201410253067A CN 105205296 A CN105205296 A CN 105205296A
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density value
porosity
reservoir
value
skeletal density
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CN201410253067.6A
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Inventor
郭旭升
郑天发
赵陵
凡睿
严伟
王良军
程斯洁
李素兰
周依南
程丽
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China Petroleum and Chemical Corp
Sinopec Exploration Southern Co
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China Petroleum and Chemical Corp
Sinopec Exploration Southern Co
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Abstract

The invention provides a method for calculating the porosity of a shale gas reservoir, and belongs to the field of petroleum and natural gas exploration and development and geophysics. The method includes the steps that 1, a core porosity value and a core density value obtained by helium method analysis, conventional logging data and a skeleton density and volume model are combined to obtain core skeleton density values by inversion; 2, the core skeleton density values obtained in the step1 and an ECS element curve are combined to obtain reservoir rock skeleton density value inversion models, changing along with depth, of all sampling points; 3, the reservoir rock skeleton density value inversion models obtained in the step2 and a density, porosity and volume model are combined to obtain the porosity of the reservoir by inversion.

Description

A kind of method asking for shale gas reservoir porosity
Technical field
The invention belongs to petroleum natural gas exploration, geophysics field, be specifically related to a kind of method asking for shale gas reservoir porosity, be particularly useful for the unconventionaloil pool such as shale gas, coal-seam gas field.
Background technology
Along with expanding economy, hydrocarbon resources is subject to increasing attention.Except conventional gas and oil exploration constantly obtains new discovery, the exploration of unconventional petroleum resources also obtains comparatively quantum jump.Shale gas is subject to the attention of various countries as unconventionaloil pool, and the shale gas exploration of China also achieves progress, and the shale gas probing exploitation of some blocks has obtained high industrial gas.Current shale gas reservoir porosity asked for direct method, i.e. method acquisition pores porosity by experiment.(patent No.: 201110155601.6) disclose a kind of method measuring mud shale factor of porosity, the present invention can measure the factor of porosity of rock sample, avoids the inconvenience that mud shale drills through rock core in patented invention such as " method for measuring porosity of mud shale ".But utilize measuring factor of porosity to there are some problems: the rock core of object reservoir all can not be taken in exploration, moreover some ground environments are complicated, prior art also can not complete the work of coring, and expense of coring and experimental analysis costly also govern the widespread use of this method.
Indirectly ask for porosity method namely by Well Logging Data Inversion porosity method, one is by analyzing the responsive logging trace of shale gas reservoir, utilize the method establishment sensitivity curve of mathematical statistics and the relation of core analysis porosity, regression formula, eventually through regression formula inverting reservoir porosity.But quantity statistics method is stablized in sedimentary environment, the similar region of reservoir characteristic can be promoted out, if reservoir characteristic change greatly, statistic law regression formula inverted porosity is just difficult to popularization.
Another kind is physically based deformation volume-based model, and when processing Reservoir Section, given different reservoir rock skeleton value carrys out inverting reservoir porosity.Open non-patent literature as delivered in the June, 2009 such as the beginning of spring of rectifying " capturing the method that well logging calculates Potential Volcanic Reservoir factor of porosity based on element " on " Xinjiang oil geology " (number of the edition ISSN1001-3873) the 30th volume the 3rd phase, the method is by setting up the sensitive relations of rock core skeletal density value and ECS single element, find out responsive elemental profiles, set up rock core skeletal density value and these sensitive elements curved line relations again, obtain the reservoir rock skeletal density curve with change in depth, then inverted porosity.
But all there are some problems in this technology:
1, volume-based model is not by the impact of reservoir characteristic, can apply, but the reservoir to mineral constituent complexity, choosing of matrix parameter value is the difficult point that it faces.
2, the basis that said method can realize is the rock core skeleton value possessing experimental analysis, do not do rock core skeleton pH-value determination pH experiment time, the method be difficult to realize.
Summary of the invention
The object of the invention is to solve the difficult problem existed in above-mentioned prior art, a kind of method asking for shale gas reservoir porosity is provided, the accurate and effective factor of porosity being finally inversed by shale gas reservoir.
The present invention is achieved by the following technical solutions:
Ask for a method for shale gas reservoir porosity, comprising:
(1) inverting that the density value of the core porosity value obtained with the analysis of helium method and rock core, Using Conventional Logs and skeletal density volume-based model combined obtains rock core skeletal density value;
(2) rock core skeletal density value step (1) obtained is combined the reservoir rock skeletal density value inverse model of each sampled point obtained with change in depth with ECS elemental profiles;
(3) reservoir rock skeletal density value inverse model step (2) obtained obtains reservoir porosity in conjunction with the inverting of density porosity volume-based model.
Described step (1) is achieved in that
Formula inverting is below utilized to obtain rock core skeletal density value:
ρ ma=(ρ b-φρ f)/(1-φ)
ρ in formula ma, ρ b, ρ fbe respectively rock core density value, the pore fluid density value of rock core skeletal density value, the acquisition of helium method, g/cm 3; φ is the core porosity value that helium method obtains, decimal.
Described step (2) comprising:
(21) according to shale reservoir total rock X diffraction experiment data, specify the mineral constituent of shale reservoir, determine corresponding ECS geochemical well logging curve according to the main component of mineral;
(22) the ECS constituent content value that each rock core skeletal density value is corresponding is determined;
(23) value of these two kinds of elements of Si, AL of the corresponding degree of depth of the rock core skeletal density value that obtains of determining step (1), obtains the rock core skeletal density value ρ that each core sample is corresponding maand ECS logs well DWAL, DWSI constituent content value obtained, then set up ρ by statistical study mawith the relational expression of DWAL, DWSI, i.e. reservoir rock skeletal density value inverse model, as follows:
ρ ma=a*(DWSI)+b*(DWAL)+f(x 1、x 2......x m)+P
ρ in formula mafor reservoir rock skeletal density value, g/cm 3; DWSI, DWAL are respectively the content of elemental silicon, the content of element aluminum, Kgf/Kgf, f (x 1, x 2... x m) be extender, change, x with Reservoir Minerals change of component 1, x 2, x mfor element x 1, x 2, x mcontent, m>=0, a, b are coefficient, and P is constant term;
Coefficient a, b ..., constant term P ask for according to system of equations, as follows:
Known parameters in system of equations: P ma1, P ma2..., P manfor rock core skeletal density value; (DWSI) 1, (DWSI) 2..., (DWSI) nfor the silicon content value that rock core skeletal density value is corresponding; (DWAL) 1, (DWAL) 2..., (DWAL) nfor the aluminium element content value that rock core skeletal density value is corresponding, solving equation group obtains a, b, P value, in like manner tries to achieve extender f (x 1, x 2..., x m) in coefficient.
Density porosity volume-based model in described step (3) is:
φ=(ρ mab)/(ρ maf)
In formula, φ is reservoir porosity.
Compared with prior art, the invention has the beneficial effects as follows: the present invention is a kind of technology utilizing reservoir rock skeletal density value to carry out inverting shale gas reservoir porosity, the factor of porosity being finally inversed by shale gas reservoir that can be accurate and effective.This technology not only avoid the shortcoming that Statistics Method calculates factor of porosity universality difference, and also compensate for when not having rock core skeletal density value experimental data, reservoir rock skeletal density value chooses difficult shortcoming, also saves the expense of ad hoc analysis matrix parameter experiment simultaneously.Improve porosity inversion precision, shale gas testing can be served better and select layer, instruct exploration deployment.Shale gas reserves are huge, and porosity inversion can be accurately assessment shale gas reserves, readjusts the energy structure, promotes that industrial upgrading is contributed.Shale gas is clean energy resource, verifies shale gas reserves, promotes widely using of shale gas, can promote environmental protection;
The technology of the present invention is not only helpful to the inverting of shale gas reservoir porosity, also can promote out, for the porosity calculation of complex lithology reservoir is offered reference.
Accompanying drawing explanation
Fig. 1 is the step block diagram of the inventive method;
Fig. 2 is XX wellhole porosity calculating achievement figure in example of the present invention;
Fig. 3 is XX wellhole porosity computational accuracy analysis chart.
Embodiment
Below in conjunction with accompanying drawing, the present invention is described in further detail:
The present invention analyzes porosity value based on helium method to combine with ECS (element captures well logging) and ask for shale gas reservoir rock skeletal density value, and then utilize the technology of physical size model inversion shale gas factor of porosity, shale gas reservoir porosity can be finally inversed by accurately.Technology provided by the invention comprises: obtain the core porosity value of helium method analysis and the density value of rock core, utilize density x volume model inversion to obtain rock core skeletal density value; Set up rock core skeletal density value and ECS to log well the relational model of constituent content, obtain reservoir rock skeletal density value model, and then inverting reservoir porosity.
As shown in Figure 1, the embodiment of the technology of the present invention is:
(1) inverting that combines of experimental data, Using Conventional Logs and skeletal density volume-based model obtains rock core skeletal density value.
Using well more complete for experimental data as modeling well, modeling well shale gas Reservoir Section has a large amount of helium methods to analyze porosity data, step (1) is analyzed factor of porosity for helium method and is tested the factor of porosity, the density data that provide and combine with density porosity volume-based model, inverting obtains the rock core skeletal density value that in the experiment of helium method, each core sample is corresponding, and rock core skeletal density value volume-based model is:
ρ ma=(ρ b-φρ f)/(1-φ)
ρ in formula ma, ρ b, ρ fbe respectively rock core skeletal density value, the experiment of helium method density value, pore fluid density value, g/cm 3; φ is helium method experiment porosity value, decimal.
(2) rock core skeletal density value is combined the reservoir rock skeletal density value inverse model of each sampled point obtained with change in depth with ECS elemental profiles.
The rock core skeletal density value obtained due to step (1) is discrete data, the reservoir rock skeletal density value of each sampled point can not be characterized, reacting each depth point reservoir rock skeletal density value curve to obtain a continuous print, needing to set up the rock core skeletal density value of these core samples and the relational expression of logging trace.Rock core skeletal density value refers to the discrete data that data by experiment obtains log show as discrete point; Reservoir rock skeletal density value refers to the continuous data asked for by data, log shows as a continuous print curve line.
Shale gas reservoir ECS logs well available stratum essential element Si, Al, Ca, Fe, S, Ti, Gd.The analysis of shale gas reservoir total rock X diffraction experiment is known, shale gas Reservoir Minerals is mainly clay, quartz, containing a small amount of carbonatite.In stratum, often kind of mineral have very fixing chemical element composition, clay and aluminium element in close relations, quartz is closely related with element silicon, carbonatite is relevant with calcium constituent, therefore AL can be chosen, Si, these three kinds of units of Ca usually characterize the mineral of shale gas reservoir, can determine that ECS elemental profiles that shale reservoir essential mineral is corresponding is element silicon curve and aluminium element curve and calcium constituent curve, the comprehensive skeletal density value of multi mineral that what the skeletal density value due to rock core reflected is, so these three kinds of elements available set up the reservoir rock skeletal density value relational model obtained with step (1).
Step (2) is divided into three steps:
1. according to shale reservoir total rock X diffraction experiment data, specify the mineral constituent of shale reservoir, determine corresponding ECS geochemical well logging curve according to the main component of mineral.
2. ECS constituent content value corresponding to each rock core skeletal density value (rock core skeletal density value and the degree of depth thereof and ECS elemental profiles are known, just can read ECS curve values (i.e. constituent content value) by the degree of depth that rock core skeletal density value is corresponding) is determined.The value of these three kinds of elements of Si, AL, Ca of the corresponding degree of depth of the rock core skeletal density value that determining step (1) obtains, so just obtains the rock core skeletal density value ρ that each core sample is corresponding maand ECS logs well DWAL, DWSI, DWCA constituent content value obtained, ρ can be set up by statistical study mawith the reservoir rock skeletal density value model of DWAL, DWSI, DWCA.
3. the relation of rock core skeletal density value and ECS constituent content is set up, obtain reservoir rock skeletal density value model, because ECS DWAL, DWSI, the DWCA obtained that log well is a continuous print curve, the reservoir rock skeletal density value so obtained also is a continuous print curve, and reservoir rock skeletal density value model is as follows:
ρ ma=-7.2171*(DWSI)-8.7361*(DWAL)-7.6751*(DWCA)+5.7083
ρ in formula mafor reservoir rock skeletal density value, g/cm 3; DWSI, DWAL, DWCA are respectively content, the content of element aluminum, the content of element calcium of the elemental silicon obtained of logging well, Kgf/Kgf.
(3) reservoir rock skeletal density value inverse model obtains reservoir porosity in conjunction with the inverting of density porosity volume-based model.Density porosity volume-based model is:
φ=(ρ mab)/(ρ maf)
In formula, φ is reservoir porosity, decimal; ρ ma, ρ b, ρ fbe respectively reservoir rock skeletal density value, well logging density value, pore fluid density value, g/cm 3.
In order to verify the precision of applicability of the present invention and calculating.The reservoir rock skeletal density value model inverted porosity technology utilizing modeling well to set up is applied in inverted porosity in XX well.
The reservoir rock skeletal density value inversion technique determined above-mentioned steps (2) can obtain reservoir rock skeletal density value in conjunction with the ECS of XX well constituent content curve of logging well, if Fig. 2 is XX wellhole porosity calculating achievement figure, 8th road is reservoir rock skeletal density curve, first to the 5th road is ECS constituent content logging trace, and the 6th road is conventional logging densimetric curve.
Can inverting reservoir porosity to the density x volume model of reservoir rock skeletal density curve integrating step (3) that step (2) is determined.In Fig. 2, XX well the 9th road POR is the factor of porosity utilizing the inverting of foregoing invention technology, and C-POR is that helium method analyzes factor of porosity, is discrete data, represents in figure with shaft-like.Can find out that the factor of porosity of the technology of the present invention inverting and helium method are analyzed factor of porosity and had good consistance from the contrast figure.
Fig. 3 further illustrates the feature that factor of porosity applicability is strong, precision is high that the present invention calculates.Fig. 3 is the precision analysis of XX wellhole porosity, and well logging that the factor of porosity of the technology of the present invention inverting and ordinate represent calculates factor of porosity and helium method and analyzes the core analysis porosity that factor of porosity and horizontal ordinate represent and have higher correlativity.The test of XX well shale gas reservoir fracturing also all obtains industrial gas.
Technique scheme is one embodiment of the present invention, for those skilled in the art, on the basis that the invention discloses application process and principle, be easy to make various types of improvement or distortion, and the method be not limited only to described by the above-mentioned embodiment of the present invention, therefore previously described mode is just preferred, and does not have restrictive meaning.

Claims (4)

1. ask for a method for shale gas reservoir porosity, it is characterized in that: described method comprises:
(1) inverting that the density value of the core porosity value obtained with the analysis of helium method and rock core, Using Conventional Logs and skeletal density volume-based model combined obtains rock core skeletal density value;
(2) rock core skeletal density value step (1) obtained is combined the reservoir rock skeletal density value inverse model of each sampled point obtained with change in depth with ECS elemental profiles;
(3) reservoir rock skeletal density value inverse model step (2) obtained obtains reservoir porosity in conjunction with the inverting of density porosity volume-based model.
2. the method asking for shale gas reservoir porosity according to claim 1, is characterized in that: described step (1) is achieved in that
Formula inverting is below utilized to obtain rock core skeletal density value:
ρ ma=(ρ b-φρ f)/(1-φ)
ρ in formula ma, ρ b, ρ fbe respectively rock core density value, the pore fluid density value of rock core skeletal density value, the acquisition of helium method, g/cm 3; φ is the core porosity value that helium method obtains, decimal.
3. the method asking for shale gas reservoir porosity according to claim 2, is characterized in that: described step (2) comprising:
(21) according to shale reservoir total rock X diffraction experiment data, specify the mineral constituent of shale reservoir, determine corresponding ECS geochemical well logging curve according to the main component of mineral;
(22) the ECS constituent content value that each rock core skeletal density value is corresponding is determined;
(23) value of these two kinds of elements of Si, AL of the corresponding degree of depth of the rock core skeletal density value that obtains of determining step (1), obtains the rock core skeletal density value ρ that each core sample is corresponding maand ECS logs well DWAL, DWSI constituent content value obtained, then set up ρ by statistical study mawith the relational expression of DWAL, DWSI, i.e. reservoir rock skeletal density value inverse model, as follows:
ρ ma=a*(DWSI)+b*(DWAL)+f(x 1、x 2......x m)+P
ρ in formula mafor reservoir rock skeletal density value, g/cm 3; DWSI, DWAL are respectively the content of elemental silicon, the content of element aluminum, Kgf/Kgf, f (x 1, x 2... x m) be extender, change, x with Reservoir Minerals change of component 1, x 2, x mfor element x 1, x 2, x mcontent, m>=0, a, b are coefficient, and P is constant term;
Coefficient a, b ..., constant term P ask for according to system of equations, as follows:
Known parameters in system of equations: P ma1, P ma2..., P manfor rock core skeletal density value; (DWSI) 1, (DWSI) 2..., (DWSI) nfor the silicon content value that rock core skeletal density value is corresponding; (DWAL) 1, (DWAL) 2..., (DWAL) nfor the aluminium element content value that rock core skeletal density value is corresponding, solving equation group obtains a, b, P value, in like manner tries to achieve extender f (x 1, x 2..., x m) in coefficient.
4. the method asking for shale gas reservoir porosity according to claim 3, is characterized in that: the density porosity volume-based model in described step (3) is:
φ=(ρ mab)/(ρ maf)
In formula, φ is reservoir porosity.
CN201410253067.6A 2014-06-09 2014-06-09 Method for calculating porosity of shale gas reservoir Pending CN105205296A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105825055A (en) * 2016-03-16 2016-08-03 西南石油大学 Method for computing relative content of CO2 in formation by using well-log information
CN106019403A (en) * 2016-06-08 2016-10-12 西北大学 Self-generation self-storage hydrocarbon reservoir porosity measurement method
CN106295113A (en) * 2016-07-15 2017-01-04 中国海洋石油总公司 A kind of method for quantitatively evaluating of complex oil and gas reservoir permeability
CN108037528A (en) * 2017-09-25 2018-05-15 中国石油化工股份有限公司 Porosity prediction method and system of few wellblock based on statistics rock physics modeling
CN108548765A (en) * 2018-03-27 2018-09-18 中国石油天然气集团有限公司 A kind of porosity calculation method for the soil skeleton that becomes sticky

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105825055A (en) * 2016-03-16 2016-08-03 西南石油大学 Method for computing relative content of CO2 in formation by using well-log information
CN106019403A (en) * 2016-06-08 2016-10-12 西北大学 Self-generation self-storage hydrocarbon reservoir porosity measurement method
CN106295113A (en) * 2016-07-15 2017-01-04 中国海洋石油总公司 A kind of method for quantitatively evaluating of complex oil and gas reservoir permeability
CN108037528A (en) * 2017-09-25 2018-05-15 中国石油化工股份有限公司 Porosity prediction method and system of few wellblock based on statistics rock physics modeling
CN108037528B (en) * 2017-09-25 2019-08-30 中国石油化工股份有限公司 Porosity prediction method and system of few wellblock based on statistics rock physics modeling
CN108548765A (en) * 2018-03-27 2018-09-18 中国石油天然气集团有限公司 A kind of porosity calculation method for the soil skeleton that becomes sticky
CN108548765B (en) * 2018-03-27 2020-11-06 中国石油天然气集团有限公司 Porosity calculation method for clay-changing framework

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