This letter investigates the wavelet transform, as well as the principle and the method of the noise reduction based on wavelet transform, it chooses the threshold noise reduction, and discusses in detail the principl...This letter investigates the wavelet transform, as well as the principle and the method of the noise reduction based on wavelet transform, it chooses the threshold noise reduction, and discusses in detail the principles, features and design steps of the threshold method. Rigrsure, heursure, sqtwolog and minimization four kinds of threshold selection method are compared qualitatively, and quantitatively. The wavelet analysis toolbox of MATLAB helps to realize the computer simulation of the signal noise reduction. The graphics and calculated standard deviation of the various threshold noise reductions show that, when dealing with the actual pressure signal of the oil pipeline leakage, sqtwolog threshold selection method can effectively remove the noise. Aiming to the pressure signal of the oil pipeline leakage, the best choice is the wavelet threshold noise reduction with sqtwolog threshold. The leakage point is close to the actual position, with the relative error of less than 1%.展开更多
Compared with conventional well, herringbone-like laterals wells can increase the area of oil release, and can reduce the number of wellhead slots of platforms,?and?also can greatly improve the development efficiency....Compared with conventional well, herringbone-like laterals wells can increase the area of oil release, and can reduce the number of wellhead slots of platforms,?and?also can greatly improve the development efficiency. Based on threshold pressure gradient in heavy oil reservoir,?and?the applied principle of mirror reflection and superposition, the pressure distribution equation of herringbone-like laterals wells is obtained in heavy oil reservoir. Productivity model of herringbone-like laterals wells is proposed by reservoir-wellbore steady seepage. The example shows that the productivity model is great accuracy?to?predict the productivity of herringbone-like laterals wells. The model is used to analyze the branching length, branching angle, branching symmetry, branching position and spacing and their effects on productivity of herringbone-like laterals wells. The principle of optimizing the well shape of herringbone-like laterals wells is proposed.展开更多
In exploration for tight oil, the content and saturation of hydrocarbon in the tight reservoir is a key factor for evaluating the reserve. Therefore, it is necessary to study the geological history of hydrocarbon accu...In exploration for tight oil, the content and saturation of hydrocarbon in the tight reservoir is a key factor for evaluating the reserve. Therefore, it is necessary to study the geological history of hydrocarbon accumulation and the tight oil charging process. However, kinetic models used for petroleum development are not applicable for petroleum exploration. In this study, a static resistance model[ is proposed after analyzing resistances in ultra-slow flow in porous media. Using this model, the disco^atinuous pattern of oil charging is reproduced through incompressible Navier-Stokes equations, the phase field method and the finite element method. This study also explains macroscopic percolation behavior with microscopic flow mechanisms and discusses some issues in ultra-slow flow in a micro/nano pore-throat network. The resistance analysis reveals that capillary resistance and dissipation resistance are dominant factors in the mechanism of oil accumulation in tight reservoirs. Numerical simulations show that pressure thresholds exist and result in discontinuous oil charging. Generally, it is proven that the static model is more applicable than kinetic models in describing oil accumulation in tight reservoirs.展开更多
This paper presents a modeling procedure for deriving a single value measurebased on a regression model, and a method for determining a statistical threshold value asidentification criterion of normal or abnormal stat...This paper presents a modeling procedure for deriving a single value measurebased on a regression model, and a method for determining a statistical threshold value asidentification criterion of normal or abnormal states of machine wear. A real numerical example isexamined by the method and identification criterion presented. The results indicate that thejudgments by the presented methods are basically consistent with the real facts, and therefore themethod and identification criterion are valuable for judging the normal or abnormal state of machinewear based on oil analysis.展开更多
The paper discussed the physical and chemical properties of cooking oil vapor(COV) and its biological effects. The study showed that: (1)By ultraviolet spectrophotometry, the method to determine the concentration of C...The paper discussed the physical and chemical properties of cooking oil vapor(COV) and its biological effects. The study showed that: (1)By ultraviolet spectrophotometry, the method to determine the concentration of COV was simple, reliable and suitable; (2)At 220℃, about 60%-80% particles′ diameter of COV were less than 10 μm which referred to they are capable of reaching the deeper parts of the respiratory tract; (3)Pulmonary toxicity study of COV revealed that in acute toxicity test, there was lung tissue injury in rats and the degree increased as the concentration of oil vapor increased; subacute test in rats indicated that pulmonary injury might be the result of lipid peroxidation brought about by the activation of more general free radical system; (4)The average concentration of emitted oil vapor in the environment ranged from 0.10 to 0.20 mg/m3, the emission outlets in most restaurants were very simple or located in residential areas without any filtering device; (5)Irritative effect threshold levels of COV to volunteers and the effects on occupational exposed cooks also suggested that COV might produce harmful effects on pulmonary function in occupationally exposed personnel.展开更多
文摘This letter investigates the wavelet transform, as well as the principle and the method of the noise reduction based on wavelet transform, it chooses the threshold noise reduction, and discusses in detail the principles, features and design steps of the threshold method. Rigrsure, heursure, sqtwolog and minimization four kinds of threshold selection method are compared qualitatively, and quantitatively. The wavelet analysis toolbox of MATLAB helps to realize the computer simulation of the signal noise reduction. The graphics and calculated standard deviation of the various threshold noise reductions show that, when dealing with the actual pressure signal of the oil pipeline leakage, sqtwolog threshold selection method can effectively remove the noise. Aiming to the pressure signal of the oil pipeline leakage, the best choice is the wavelet threshold noise reduction with sqtwolog threshold. The leakage point is close to the actual position, with the relative error of less than 1%.
文摘Compared with conventional well, herringbone-like laterals wells can increase the area of oil release, and can reduce the number of wellhead slots of platforms,?and?also can greatly improve the development efficiency. Based on threshold pressure gradient in heavy oil reservoir,?and?the applied principle of mirror reflection and superposition, the pressure distribution equation of herringbone-like laterals wells is obtained in heavy oil reservoir. Productivity model of herringbone-like laterals wells is proposed by reservoir-wellbore steady seepage. The example shows that the productivity model is great accuracy?to?predict the productivity of herringbone-like laterals wells. The model is used to analyze the branching length, branching angle, branching symmetry, branching position and spacing and their effects on productivity of herringbone-like laterals wells. The principle of optimizing the well shape of herringbone-like laterals wells is proposed.
基金supported by the Chinese Major National Scientific and Technological Program (2011ZX05001)Chinese Postdoctoral Fund (2013M540114)
文摘In exploration for tight oil, the content and saturation of hydrocarbon in the tight reservoir is a key factor for evaluating the reserve. Therefore, it is necessary to study the geological history of hydrocarbon accumulation and the tight oil charging process. However, kinetic models used for petroleum development are not applicable for petroleum exploration. In this study, a static resistance model[ is proposed after analyzing resistances in ultra-slow flow in porous media. Using this model, the disco^atinuous pattern of oil charging is reproduced through incompressible Navier-Stokes equations, the phase field method and the finite element method. This study also explains macroscopic percolation behavior with microscopic flow mechanisms and discusses some issues in ultra-slow flow in a micro/nano pore-throat network. The resistance analysis reveals that capillary resistance and dissipation resistance are dominant factors in the mechanism of oil accumulation in tight reservoirs. Numerical simulations show that pressure thresholds exist and result in discontinuous oil charging. Generally, it is proven that the static model is more applicable than kinetic models in describing oil accumulation in tight reservoirs.
文摘This paper presents a modeling procedure for deriving a single value measurebased on a regression model, and a method for determining a statistical threshold value asidentification criterion of normal or abnormal states of machine wear. A real numerical example isexamined by the method and identification criterion presented. The results indicate that thejudgments by the presented methods are basically consistent with the real facts, and therefore themethod and identification criterion are valuable for judging the normal or abnormal state of machinewear based on oil analysis.
文摘The paper discussed the physical and chemical properties of cooking oil vapor(COV) and its biological effects. The study showed that: (1)By ultraviolet spectrophotometry, the method to determine the concentration of COV was simple, reliable and suitable; (2)At 220℃, about 60%-80% particles′ diameter of COV were less than 10 μm which referred to they are capable of reaching the deeper parts of the respiratory tract; (3)Pulmonary toxicity study of COV revealed that in acute toxicity test, there was lung tissue injury in rats and the degree increased as the concentration of oil vapor increased; subacute test in rats indicated that pulmonary injury might be the result of lipid peroxidation brought about by the activation of more general free radical system; (4)The average concentration of emitted oil vapor in the environment ranged from 0.10 to 0.20 mg/m3, the emission outlets in most restaurants were very simple or located in residential areas without any filtering device; (5)Irritative effect threshold levels of COV to volunteers and the effects on occupational exposed cooks also suggested that COV might produce harmful effects on pulmonary function in occupationally exposed personnel.
