The conventional measurement of a relative permeability curve (RPC) is usually conducted at room temperature, which is much lower than the reservoir temperature. Previous research work on high temperature relative...The conventional measurement of a relative permeability curve (RPC) is usually conducted at room temperature, which is much lower than the reservoir temperature. Previous research work on high temperature relative permeability mainly take oil-wetted cores as objective. In this paper, laboratory test and measurement are conducted using water-wet cores from the Lunnan Oilfield. Since irreducible water saturation (Swi) is a critical factor that affects and controls the relative permeability curve, special tests are conducted to measure Swi at different temperatures for water-wet cores in the course of the experiment of relative permeability. The experimental results indicate that for the water-wet cores Swi decreased with the increasing temperature from ambient to 105℃,and the relative permeability curve shifted in a low water saturation direction, i.e. moved toward the left, while it moved toward the right for oil wetness reservoirs. Seen from both macroscopic and microcosmic view, the reasons and mechanisms of relative permeability change with temperature are discussed, and factors including core wetness, viscosity force, capillary forces, contact angle, interfacial tension change are considered.展开更多
The irreducible water saturation(Swir) is a significant parameter for relative permeability prediction and initial hydrocarbon reserves estimation.However,the complex pore structures of the tight rocks and multiple fa...The irreducible water saturation(Swir) is a significant parameter for relative permeability prediction and initial hydrocarbon reserves estimation.However,the complex pore structures of the tight rocks and multiple factors of the formation conditions make the parameter difficult to be accurately predicted by the conventional methods in tight gas reservoirs.In this study,a new model was derived to calculate Swir based on the capillary model and the fractal theory.The model incorporated different types of immobile water and considered the stress effect.The dead or stationary water(DSW) was considered in this model,which described the phenomena of water trapped in the dead-end pores due to detour flow and complex pore structures.The water film,stress effect and formation temperature were also considered in the proposed model.The results calculated by the proposed model are in a good agreement with the experimental data.This proves that for tight sandstone gas reservoirs the Swir calculated from the new model is more accurate.The irreducible water saturation calculated from the new model reveals that Swir is controlled by the critical capillary radius,DSW coefficient,effective stress and formation temperature.展开更多
This paper, using the monads theory in the topological space, gives a new characterization of irreducible sets in the nonstandard enlarged models. Further, the discretization expression of Sober topological spaces is ...This paper, using the monads theory in the topological space, gives a new characterization of irreducible sets in the nonstandard enlarged models. Further, the discretization expression of Sober topological spaces is presented.展开更多
This paper obtains a necessary and sufficient condition for an irreducible complex matrix whose comparison matrix is a singular M-matrix to be singular. This is used to establish a necessary and sufficient condition f...This paper obtains a necessary and sufficient condition for an irreducible complex matrix whose comparison matrix is a singular M-matrix to be singular. This is used to establish a necessary and sufficient condition for a boundary point of Brualdi’s inclusion region of the eigenvalues of an irreducible complex matrix to be an eigenvalue.展开更多
Irreducible graphs are those graphs which can hot be embedded on some surface but deleting ally edge of this graph, the resultant graph can be embedded on the surface. This paper characterizes one kind of irreducible ...Irreducible graphs are those graphs which can hot be embedded on some surface but deleting ally edge of this graph, the resultant graph can be embedded on the surface. This paper characterizes one kind of irreducible graphs and it is shown that the lower bound number of irreducible graphs for the surface of genus n is 2 × 16n.展开更多
This paper an cited instances in illustration of the incorrectness of the criteria of asymptotic stability of a class of nonlinear large seale system that L_j·T·Grujie gave in paper [1] by the comparison the...This paper an cited instances in illustration of the incorrectness of the criteria of asymptotic stability of a class of nonlinear large seale system that L_j·T·Grujie gave in paper [1] by the comparison theory and then corrected it,and has given the sufficient conditions of the asymptotic stability.展开更多
The variety ddpM of de Morgan algebras with double demi-pseudocomplementation consists of those algebras （L; ∧ , ∨ , , , ＋ , 0, 1） of type （2, 2, 1, 1, 1, 0, 0） where （L; ∧ , ∨ , , 0, 1） is a de Morgan alge...The variety ddpM of de Morgan algebras with double demi-pseudocomplementation consists of those algebras （L; ∧ , ∨ , , , ＋ , 0, 1） of type （2, 2, 1, 1, 1, 0, 0） where （L; ∧ , ∨ , , 0, 1） is a de Morgan algebra, （L; ∧ , ∨ , , ＋ , 0, 1） is a double demi-p-lattice and the operations x → x , x → x and x → x ＋ are linked by the identities x = x , x ＋ = x ＋ and x ＋ = x ＋ . In this paper, we characterize congruences on a ddpM-algebra, and give a description of the subdirectly irreducible algebras.展开更多
Using the symbol calculus developed by Berezin, Kree and Raczka, it is shown that the algebra generated by the canonical commutation relation (CCR) is splitted into creation part and annhilation part with holomorphic ...Using the symbol calculus developed by Berezin, Kree and Raczka, it is shown that the algebra generated by the canonical commutation relation (CCR) is splitted into creation part and annhilation part with holomorphic and anti-bolomorphic symbols respectively. Further. in the Weyl representation of CCR, three Weyl operators will constitute an irreducible set of the fall CCR-algebra if some number theoretic conditions are satisfied.展开更多
In this paper Dirce group is constructed on the basis of algebraic properties of α’s and β’s matrices in Dirac equation. It is then establisbed that the dimensions of the matrices must be four (i. e., 4 × 4 m...In this paper Dirce group is constructed on the basis of algebraic properties of α’s and β’s matrices in Dirac equation. It is then establisbed that the dimensions of the matrices must be four (i. e., 4 × 4 matrices), and the concrete formulations of them in Pauli-Dirac representation are derived.展开更多
For any prime p, all finite noncyclic p-groups which contain a self-centralizing cyclic normal subgroup are determined by using cohomological techniques. Some applications are given, including a character theoretic de...For any prime p, all finite noncyclic p-groups which contain a self-centralizing cyclic normal subgroup are determined by using cohomological techniques. Some applications are given, including a character theoretic description for such groups.展开更多
Some spectral characterizations of positive operators on Hilbert lattices are presented. The application of these results can yield some equivalent relations of an irreducible positive operator. Some related results f...Some spectral characterizations of positive operators on Hilbert lattices are presented. The application of these results can yield some equivalent relations of an irreducible positive operator. Some related results for positive operators on Hilbert lattice are also obtained.展开更多
We have used ab initio pseudopotential method to generate basis wavefunctions and eigen energies to carry out first principle calculations of the static macroscopic dielectric constant for GaAs and GaP.The resulted co...We have used ab initio pseudopotential method to generate basis wavefunctions and eigen energies to carry out first principle calculations of the static macroscopic dielectric constant for GaAs and GaP.The resulted converged random phase approximation(RPA)value is 12.55 and 10.71,in excellent agreement to the experimental value of 12.4 and 10.86,respectively.The inclusion of the exchange correlation contribution makes the calculated result slightly worsen,A convergence test with respect to the number of k points in Brillouin zone(BZ)integration was carried out.Sixty irreducible BZk points were used to achieve the converged results.Integration with only 10 special k points increased the RPA value by 15%.展开更多
By taking the concept of weight conservation into account,new solations of Yang-Baxter equation without spectral parameter are obtained through the non-standard A-matrix on the feensorial space V^(1/2) (j≠1/2)in term...By taking the concept of weight conservation into account,new solations of Yang-Baxter equation without spectral parameter are obtained through the non-standard A-matrix on the feensorial space V^(1/2) (j≠1/2)in terms of the irreducible representation of the quantum universal enveloping algebra SLq(2).The non-standard R-matrix J?1/21 is obtained in an explicit form for j=1.展开更多
A gauge invariant and Lorentz-irreducible three-gluon conserved vector current is constructed,and the mass of the vector glueball is calculated in the framework of the Quantum Chromodynamics sum rules.
In this note the authors investigates the property of the GF(2)-modules for the wreath products Sz(q)wrCt,and establish some sufficient condition for a Sz(q)wrCt, GF(2)-module to be natural.
In 1984, Isaacs proposed the theories of Bπ-character and Iπ-character in π-separated group. This paper gives some new extension conditions of Iπ characters.
The class of E＇-matrices introduced in [4] is a subclass of Q0-matrices whose proper principal submatrices are Q--matrices. In this paper, we investigate the relation of the class E＇ to other known matrix classes an...The class of E＇-matrices introduced in [4] is a subclass of Q0-matrices whose proper principal submatrices are Q--matrices. In this paper, we investigate the relation of the class E＇ to other known matrix classes and obtain a series of necessary and sufficient conditions for E＇-matrices.展开更多
Based on the measurement mechanism of mobility in pressure measurement while drilling, through analyzing a large number of mobility data, it is found that under the condition of water-based mud drilling, the product o...Based on the measurement mechanism of mobility in pressure measurement while drilling, through analyzing a large number of mobility data, it is found that under the condition of water-based mud drilling, the product of mobility from pressure measurement while drilling and the viscosity of mud filtrate is infinitely close to the water phase permeability under the residual oil in relative permeability experiment. Based on this, a method converting the mobility from pressure measurement while drilling to core permeability is proposed, and the permeability based on Timur formula has been established. Application of this method in Penglai 19-9 oilfield of Bohai Sea shows:(1) Compared with the permeability calculated by the model of adjacent oilfields, the permeability calculated by this model is more consistent with the permeability calculated by core analysis.(2) Based on the new model, the correlation between the calculated mobility of well logging and the actual drilling specific productivity index bas been established. Compared with the relationship established by using the permeability model of an adjacent oilfield, the correlation of the new model is better.(3) Productivity of four directional wells was predicted, and the prediction results are in good agreement with the actual production after drilling.展开更多
In this article,we investigate the spectral properties of a class of neutron transport operators involving elastic and inelastic collision operators introduced by Larsen and Zweifel[1].Our analysis is manly focused on...In this article,we investigate the spectral properties of a class of neutron transport operators involving elastic and inelastic collision operators introduced by Larsen and Zweifel[1].Our analysis is manly focused on the description of the asymptotic spectrum which is very useful in the study of the properties of the solution to Cauchy problem governed by such operators(when it exists).The last section of this work is devoted to the properties of the leading eigenvalue(when it exists).So,we discuss the irreducibility of the semigroups generated by these operators.We close this section by discussing the strict monotonicity of the leading eigenvalue with respect to the parameters of the operator.展开更多
文摘The conventional measurement of a relative permeability curve (RPC) is usually conducted at room temperature, which is much lower than the reservoir temperature. Previous research work on high temperature relative permeability mainly take oil-wetted cores as objective. In this paper, laboratory test and measurement are conducted using water-wet cores from the Lunnan Oilfield. Since irreducible water saturation (Swi) is a critical factor that affects and controls the relative permeability curve, special tests are conducted to measure Swi at different temperatures for water-wet cores in the course of the experiment of relative permeability. The experimental results indicate that for the water-wet cores Swi decreased with the increasing temperature from ambient to 105℃,and the relative permeability curve shifted in a low water saturation direction, i.e. moved toward the left, while it moved toward the right for oil wetness reservoirs. Seen from both macroscopic and microcosmic view, the reasons and mechanisms of relative permeability change with temperature are discussed, and factors including core wetness, viscosity force, capillary forces, contact angle, interfacial tension change are considered.
基金supported by the National Science Foundation (51904324, 51674279, 51804328)the Major National Science and Technology Project (2017ZX05009-001, 2017ZX05072)+3 种基金the Key Research and Development Program (2018GSF116004)the China Postdoctoral Science Foundation (2019T120616)the Funding for Scientific Research of China University of Petroleum East China (YJ20170013)Graduate Innovative Engineering project (YCX2019023)。
文摘The irreducible water saturation(Swir) is a significant parameter for relative permeability prediction and initial hydrocarbon reserves estimation.However,the complex pore structures of the tight rocks and multiple factors of the formation conditions make the parameter difficult to be accurately predicted by the conventional methods in tight gas reservoirs.In this study,a new model was derived to calculate Swir based on the capillary model and the fractal theory.The model incorporated different types of immobile water and considered the stress effect.The dead or stationary water(DSW) was considered in this model,which described the phenomena of water trapped in the dead-end pores due to detour flow and complex pore structures.The water film,stress effect and formation temperature were also considered in the proposed model.The results calculated by the proposed model are in a good agreement with the experimental data.This proves that for tight sandstone gas reservoirs the Swir calculated from the new model is more accurate.The irreducible water saturation calculated from the new model reveals that Swir is controlled by the critical capillary radius,DSW coefficient,effective stress and formation temperature.
基金Supported by the Natural Science Foundation of Shaanxi Province（2007A12） Supported by the Scientific Research Foundation of Shaanxi Educational Committee（11JK0507）
文摘This paper, using the monads theory in the topological space, gives a new characterization of irreducible sets in the nonstandard enlarged models. Further, the discretization expression of Sober topological spaces is presented.
文摘This paper obtains a necessary and sufficient condition for an irreducible complex matrix whose comparison matrix is a singular M-matrix to be singular. This is used to establish a necessary and sufficient condition for a boundary point of Brualdi’s inclusion region of the eigenvalues of an irreducible complex matrix to be an eigenvalue.
文摘Irreducible graphs are those graphs which can hot be embedded on some surface but deleting ally edge of this graph, the resultant graph can be embedded on the surface. This paper characterizes one kind of irreducible graphs and it is shown that the lower bound number of irreducible graphs for the surface of genus n is 2 × 16n.
文摘This paper an cited instances in illustration of the incorrectness of the criteria of asymptotic stability of a class of nonlinear large seale system that L_j·T·Grujie gave in paper [1] by the comparison theory and then corrected it,and has given the sufficient conditions of the asymptotic stability.
文摘The variety ddpM of de Morgan algebras with double demi-pseudocomplementation consists of those algebras （L; ∧ , ∨ , , , ＋ , 0, 1） of type （2, 2, 1, 1, 1, 0, 0） where （L; ∧ , ∨ , , 0, 1） is a de Morgan algebra, （L; ∧ , ∨ , , ＋ , 0, 1） is a double demi-p-lattice and the operations x → x , x → x and x → x ＋ are linked by the identities x = x , x ＋ = x ＋ and x ＋ = x ＋ . In this paper, we characterize congruences on a ddpM-algebra, and give a description of the subdirectly irreducible algebras.
文摘Using the symbol calculus developed by Berezin, Kree and Raczka, it is shown that the algebra generated by the canonical commutation relation (CCR) is splitted into creation part and annhilation part with holomorphic and anti-bolomorphic symbols respectively. Further. in the Weyl representation of CCR, three Weyl operators will constitute an irreducible set of the fall CCR-algebra if some number theoretic conditions are satisfied.
文摘In this paper Dirce group is constructed on the basis of algebraic properties of α’s and β’s matrices in Dirac equation. It is then establisbed that the dimensions of the matrices must be four (i. e., 4 × 4 matrices), and the concrete formulations of them in Pauli-Dirac representation are derived.
基金Supported by the NSF of China(11171194)by the NSF of Shanxi Province(2012011001-1)
文摘For any prime p, all finite noncyclic p-groups which contain a self-centralizing cyclic normal subgroup are determined by using cohomological techniques. Some applications are given, including a character theoretic description for such groups.
基金Supported by the National Natural Science Foundation of China(19771056,10571113)
文摘Some spectral characterizations of positive operators on Hilbert lattices are presented. The application of these results can yield some equivalent relations of an irreducible positive operator. Some related results for positive operators on Hilbert lattice are also obtained.
文摘We have used ab initio pseudopotential method to generate basis wavefunctions and eigen energies to carry out first principle calculations of the static macroscopic dielectric constant for GaAs and GaP.The resulted converged random phase approximation(RPA)value is 12.55 and 10.71,in excellent agreement to the experimental value of 12.4 and 10.86,respectively.The inclusion of the exchange correlation contribution makes the calculated result slightly worsen,A convergence test with respect to the number of k points in Brillouin zone(BZ)integration was carried out.Sixty irreducible BZk points were used to achieve the converged results.Integration with only 10 special k points increased the RPA value by 15%.
基金Supported in part by the National Natural Science Foundation of China.
文摘By taking the concept of weight conservation into account,new solations of Yang-Baxter equation without spectral parameter are obtained through the non-standard A-matrix on the feensorial space V^(1/2) (j≠1/2)in terms of the irreducible representation of the quantum universal enveloping algebra SLq(2).The non-standard R-matrix J?1/21 is obtained in an explicit form for j=1.
基金supported by the Science Fund of the Chinese Academy of Sciences。
文摘A gauge invariant and Lorentz-irreducible three-gluon conserved vector current is constructed,and the mass of the vector glueball is calculated in the framework of the Quantum Chromodynamics sum rules.
文摘In this note the authors investigates the property of the GF(2)-modules for the wreath products Sz(q)wrCt,and establish some sufficient condition for a Sz(q)wrCt, GF(2)-module to be natural.
基金Supported by the Education Hall Foundation of Zhejiang Province(20051313)
文摘In 1984, Isaacs proposed the theories of Bπ-character and Iπ-character in π-separated group. This paper gives some new extension conditions of Iπ characters.
基金Supported by the YSF of Guangdong University of Technology(062058)
文摘The class of E＇-matrices introduced in [4] is a subclass of Q0-matrices whose proper principal submatrices are Q--matrices. In this paper, we investigate the relation of the class E＇ to other known matrix classes and obtain a series of necessary and sufficient conditions for E＇-matrices.
基金Supported by the China National Science and Technology Major Project(2016ZX058-001)the CNOOC Scientific and Technological Project(CNOOC-KJ135-ZDXM36-TJ).
文摘Based on the measurement mechanism of mobility in pressure measurement while drilling, through analyzing a large number of mobility data, it is found that under the condition of water-based mud drilling, the product of mobility from pressure measurement while drilling and the viscosity of mud filtrate is infinitely close to the water phase permeability under the residual oil in relative permeability experiment. Based on this, a method converting the mobility from pressure measurement while drilling to core permeability is proposed, and the permeability based on Timur formula has been established. Application of this method in Penglai 19-9 oilfield of Bohai Sea shows:(1) Compared with the permeability calculated by the model of adjacent oilfields, the permeability calculated by this model is more consistent with the permeability calculated by core analysis.(2) Based on the new model, the correlation between the calculated mobility of well logging and the actual drilling specific productivity index bas been established. Compared with the relationship established by using the permeability model of an adjacent oilfield, the correlation of the new model is better.(3) Productivity of four directional wells was predicted, and the prediction results are in good agreement with the actual production after drilling.
文摘In this article,we investigate the spectral properties of a class of neutron transport operators involving elastic and inelastic collision operators introduced by Larsen and Zweifel[1].Our analysis is manly focused on the description of the asymptotic spectrum which is very useful in the study of the properties of the solution to Cauchy problem governed by such operators(when it exists).The last section of this work is devoted to the properties of the leading eigenvalue(when it exists).So,we discuss the irreducibility of the semigroups generated by these operators.We close this section by discussing the strict monotonicity of the leading eigenvalue with respect to the parameters of the operator.
