The Influence of In-situ Stress Gradient and Geothermal Temperature on The Calculation of Coalbed Gas Pressure

On the basis of coal seam having outcrop of coal seam and outlet on ground,the method for calculating coalbed gas pressure from the one-dimensional stable gas flow equation by considering deeply the influence of in-situ stress gradient and geothermal temperature is presented. In some mine, the theoretically computing and measuring results of coalbed gas pressure show that the in-situ stress gradient and the geothermal temperature have important influence on the calculation of coalbed gas pressure, and if the factors are drew into the calculation of coaled gas pressure,it will make the results much more accurate.     

Establishment of a crop evapotranspiration calculation model and its validation

In order to contribute knowledge on the method used to calculate the actual crop evapotranspiration, soil, crop, atmosphere, and water spatial structure were integrated into a complete system. Based on the energy balance equation and aerodynamic equation, the meteorological data was reduced and the crop physiological parameter was increased, then the crop evapotranspiration calculation model under natural conditions was derived. The crop evapotranspiration calculation model was verified by the water balance formula using data generated from corn, potato, and flue-cured tobacco grown under field conditions for three consecutive years from 2017 to 2019. The results showed that: from 2017 to 2019, the average root mean square error for measured and calculated evapotranspiration of corn, potato, and flue-cured tobacco at different growth times were 0.5948, 0.4753, and 0.3326, respectively, the mean deviation, mean absolute error, and mean relative error were small, and the coefficient of determination and consistency index were both greater than 0.9100. The measured and calculated crop evapotranspiration of the selected crops increased at first and then decreased gradually as the crops matured, and finally decreased to harvest evapotranspiration, showing a parabolic trend. The crop evapotranspiration calculation model not only reflects the actual evapotranspiration of crops at different growth time but also reflects the change law of actual crop evapotranspiration. The model does not need the correction of soil moisture content, irrigation method, and crop coefficient and can directly calculate the actual crop evapotranspiration. It has the characteristics of consistency between the calculated value and the measured value, strong applicability, simple calculation process, and high accuracy and has the best effect on monitoring soil moisture and crop water shortage sensitivity. The model is significance in that it guides for monitoring soil moisture, determining actual crop evapotranspiration, crop water shortage index, and high yield and efficiency under water-saving conditions.     

Mechanism analysis of permeability based on promoting coal matrix shrinkage by water jet

High pressure pulsed water jet (HPWJ) is a new technology of effectively improving coal seam permeability. However, the mechanism of increased permeability is not yet clear, which restricts the application of HPWJ in different coal seams. From the perspective of improving permeability by coal matrix shrinkage, the impelled dynamic equations is established based on analysis of coal dynamic effects by water jet. According to theoretical analysis of the stress state of coal matrix, it is concluded that HPWJ can promote coal matrix shrinkage, and the relationship equation between jet impact-coal matrix is derived. Besides, the gas seepage function in the coal slotted by the HPWJ is gained by using PM model, which provides theoretical support for generalizing the technology in the coal mine.     

Experimental study of coalbed methane seepage in fuxin basin

Taking raw coal samples collected from the wangying colliery in Fuxin basin as the research object, the experiment of coalbed methane seepage law is conducted by the triaxial osmoscope and the relationship between effective stress and coal permeability is presented. The experiment results indicate that the coal permeability is of stress sensitivity and tended to decline in exponent with the increment of effective stress, which is consistent with the former research results. The seepage flow curves from experiments demonstrate the nonlinear characteristics under different confining pressures and moisture contents, and it accurately reflecte the effect of coal body deformation on the coalbed methane seepage flow in the experimental process. Therefore considering the influence of effective stress on the coal body deformation, a new motion equation for the nonlinear percolation characteristic of coalbed methane is established. Moreover, the motion equation is correlated well with the experimental data, and the fitting correlation coefficients are above 99.6%.     

Numerical simulation of seepage field of gas extraction drilling of single bedding of mining-coal bed

Aiming at the problem of reasonable decorate of coal gas extraction drilling, combining with the initial and boundary condition of borehole extraction, the solid and gas coupling mathematical model of gas seepage of borehole extraction is deduced based on established control equations of seepage field and deformation field. Taking gas extraction of stone coal slit as an example, according to the characteristics of coal seam in the research, the numerical simulation method is used to obtain the distribution rule of gas pressure, coalbed gas permeability, and coalbed gas seepage velocity as well as seam deformation. The effective radius of gas extraction drilling of single bedding about mining-coal bed is determined, which provides the basis for optimum arrangement of gas extraction drilling of single bedding. The results show that the effective radius of stone coal is about 4 m. If the prolonging drilling drainage time is less than 20%, the drilling quantities would reduce by about 50%.     

Physical simulation of production performance of fractured horizontal wells in low permeability reservoir

For the fractured horizontal wells with spindle and dumbbell-shaped distribution of fracture in the Changqing oil-field, 3-D scaled physical models are utilized to simulate their production performance in elastic drive and waterflooding. The experimental results indicate that the oil production and the experimental time of two models are closely exponential function. The oil production of the horizontal well with dumbbell-shaped fracture is higher, but its decline rate is faster. The productivity formula and material balance equation of closed reservoir with elastic drive are utilized to derive the exponential form of oil production. Influence factors of oil production and its decline rate are analyzed in elastic drive. In waterflooding, the water breakthrough time of the horizontal well with spindle fracture is later than the one with dumbbell-shaped fracture. And the rate of water cut increasing of the model with spindle fracture is slower. In the initial stage of waterflooding experiment, elastic drive is still the leading position, so the oil production of the model with dumbbell-shaped fracture is higher. When the cumulative water injected exceeds 0.2 PV, the recovery percent of the model with spindle fracture is higher than the one of the model with dumbbell-shaped fracture. When the percent water cut reaches 98%, the recovery percent of the model with spindle fracture is 33.67%, while the one of the model with dumbbell-shaped fracture is 27.48%.     

Optimization and performance analysis of nitrogen expansion liquefaction process for CBM with different nitrogen content

A nitrogen expansion liquefaction process which is suitable for small-scale liquefaction plants is proposed for coalbed methane (CBM) with high nitrogen content. In order to investigate the effects of the nitrogen content on the liquefaction system performance, optimizations are done for CBM with nitrogen content among 0~70% via simulation and calculation with HYSYS when the liquefaction rate and the methane recovery rate are fixed respectively, and with the unit product liquefaction power consumption as the major index, the corresponding system performance is compared. The results show that, the system performance of CBM liquefaction process changes greatly along with nitrogen content. However, the changing is not monotonous.     

Water/oil radial flow behavior near well bore zones in oil reservoir

The flow behavior of water and oil near well bore zones in oil reservoir is radial flow. Based on the fluid displacement experiments in radial systems, the equation describing radial flow is investigated and analytical solution about the relationship between relative permeability ratio and saturation is obtained. The analytical solution is used to treat the experiment results and the two phase flow behavior of water and oil is characterized. The results show that the analytical solution can characterize the actual flow of water and oil near well bore zone. According to the radial experiments, the saturation scope in which the relative permeability ratio and saturation is linear is smaller. The flow behavior of water and oil near well bore zones is complex and nonlinear.     

不同加工处理大豆对瘤胃干物质消化率及活体外瘤胃发酵参数的动态影响研究

(目的)本文旨在研究不同加工处理大豆对瘤胃干物质消化率及活体外瘤胃发酵参数的动态影响。（方法）以豆粕、膨化全脂大豆和焙烤大豆为试验材料,利用活体外人工瘤胃产气量法,模拟奶牛TMR(DM)条件下研究不同添加水平(0、5、10、15、20%)对反刍动物活体外产气量、活体外干物质消化率及瘤胃发酵参数的影响。（结果）结果表明：（1）同一原料不同梯度之间,膨化全脂大豆24h产气量在10%添加量最小,与对照组差异显著（P＜0.05）;（2）10%、20%豆粕添加组乙酸含量、乙:丙比例与对照组差异显著（P＜0.05）;（3）豆粕与焙烤大豆24h DMD呈逐步增加的趋势,10%添加组与0%、5%添加组差异显著,膨化全脂大豆DMD呈倒抛物线,在15%添加量时最低,与对照组及5%添加组差异显著;（4）膨化全脂大豆理论最大产气量10%添加组与对照组差异显著,继续增加添加量差异不显著,产气速度在10%添加组最低,与对照组及其它试验组相比差异显著。（5）不同原料相同梯度之间,当添加量达到10%后,乙:丙比例发生显著变化（P＜0.05）,豆粕与膨化全脂大豆、焙烤大豆间乙:丙比例呈相反的变化趋势。15%添加组乙:丙比例最低,（结论）说明膨化全脂大豆与焙烤大豆以15%添加比较合适。     

Perforation-mediated modified atmosphere packaging: Part I. Development of a mathematical model

A space-and-time dependent mathematical model describing perforation-mediated modified atmosphere packages was developed for respiring commodities. The model is based primarily on fundamental laws, with empirical relations used only when no other approach can be devised or when there is a significant advantage from using an empirical approach. The computational domain is divided into four subdomains: a part of the ambient storage environment; the perforation, allowing gas exchange between the package and the ambient; the commodity layer, inside the package; and the headspace above the commodity, but also contained in the package. The package walls are rigid and impermeable to gases but heat conducting. The commodity is treated as a homogenous porous medium with distributed sinks for oxygen consumption and distributed sources for carbon dioxide production due to commodity respiration. The commodity model also accounts for water vapour production due to transpiration and removal caused by possible condensation. The effects of commodity temperature and headspace gas composition on oxygen consumption and carbon dioxide production are accounted through a respiration model. The model permits the determination of the gas mixture velocity as the solution of Darcy's law in the commodity layer and the Navier–Stokes equations in the headspace, perforation, and surrounding ambient storage area. Transport of oxygen, carbon dioxide, water vapour and nitrogen is modelled based on Maxwell–Stefan equations coupled with the Navier–Stokes equations and Darcy's law. Solubility of carbon dioxide within the commodity has been included in the model. Commodity temperature and gas mixture temperature are modelled as solutions of the energy equation in the appropriate subdomains, coupled through transpiration, condensation, and convective heat transfer at the commodity surface.     

应用施肥效应方程指导施肥的有关因素分析

近年来在合理施肥研究中,采用二次曲面效应方程反映氮、磷肥投入与产量的生产函数关系.据多点试验结果分析,二次方程均能客观地反映各点实际情况,拟合度好.但在田间运用应考虑到许多影响因素.本文拟就气候条件相近,土壤类型单一的条件下,对冬小麦田间试验结果探讨如下问题:方程中一次项与土壤初始养分测定值的关系;效应方程中一次项与二次项系数的关系;土壤养分氮、磷比例对氮、磷肥交互作用及肥效的影响;地力基础产量的估算及采用施肥效应方程推荐肥料用量的价格问题.     

STUDY ABOUT FLOW THEORY AND GOVERNING EQUATION OF GAS SEEPAGE FLOW IN COAL BEDS

This paper analyzes comprehensively the present approaches about the flow theory and governing equation of the gas seepage in China from the equations of the gas flow continuity, motion, state ane content. The viewpoint is put forward in the paper that the gas amount taking part in seepage flow is only a part of the whole gas content. The governing equation, of gas seepage flow in coal seams is set up on condition that procedures of adsorption and desorption are convertible completely.     

Mathematical Model of Selective Catalytic Reaction of Nox in Reactor and Its Simulation

As the domestic technology of selective catalytic reduction(SCR) has not been mature.A assembled-parameter dynamic mathematical model is established for the primary chemistry reaction process in SCR reactor.The mass balance equation of the NH3 adsorption-desorption on the catalyzer surface and six gas components,and total energy balance equation in SCR reactor are set up respectively.A dynamic simulation model has developed by using MATLAB simulation tool.The steady calculation for model is carried on.Based on the established dynamic simulation model,two dynamic simulation experiments have been done,which include the simulation experiment of step disturbance about NOx concentration and temperature.The simulation results current is correctl.The analyzed results indicate that the established dynamic mathematical model for SCR reactor is credible,and prove that the simulation model is practical.     

冀东冬小麦降水适宜度变化及保证率风险分析

为了更好地了解冬小麦生长期间,自然降水对其生长所需水分的满足程度,以利指导农业生产,利用降水适宜度模型、气候保证率的求算方法,对唐山地区1981—2010年冬小麦几个关键发育期期间的历年降水适宜度进行了计算,并对其进行保证率风险分析。结果表明,唐山地区冬小麦各需水关键发育期的降水适宜度各地区之间无明显差异,但年际间变化较大,返青—拔节期降水适宜度在0.05~1.00之间变化,拔节—抽穗期在0.03~0.99之间变化,灌浆期在0.04~0.88之间变化,其变异系数分别为0.79、0.72、0.65。冬小麦降水适宜度的变化趋势不显著,其10年变化速率仅0.002。冬小麦各需水关键发育期的降水适宜度在0.8以下的保证率为83%~87%,降水不能满足冬小麦生长所需,种植风险较大。降水条件是小麦生产的限制因素。     

太行山前平原土壤水分特征曲线拟合参数的确定

本文分别用BrooksandCorey ,vanGenuchten和Broadbridge White模型拟合了太行山山前平原不同层次土壤水分特征曲线 (SWC) ,并用Mualem和Burdine模型计算了土壤非饱和导水率(K)和扩散率 (D)。最能较好计算实验地点D和K的方法是用vanGenuchten模型拟和SWC(约束条件m =1- 2 /n) ,用Burdine方法计算K和D。     

Study on Methane Flow Regularity and Secondary Stress and Deformation of Coal Bady around Penetration Boreholes in Coal Seam

A new mathematical model for the coefficient of variable permeability affected by coal body, secondary stress & pressure in coalseam & a constitutive equation for gas migration are improved on the basis of the secondary stress & deformation of coal body around boreholes in coalseam. Using this model and equation,the gas flow field belongs to the 20102 experimental zone in BaiJiao coal Mine is computed & this verifies that the model & constitutive equation are both agreeable to practical results. Simultaneously, a comparison between the variable and constant permeabilities is carried out.     

Equivalent Constitutive Equations in Anti-Plane Deformation of Honeycomb Plates

Authors approach problems of anti-plane deformation in honeycomb plates by using model of polar material in which exist couple stresses. Equivalent constitutive equations are introduced in the paper and equivalent couple stresses are contained in it. It shows that in analysis of one-dimensional problem of statics the relationship of stresses to torsions and of couple stresses to strains may be negligible and this neglect simplifies analysis of problems.     

Performance analysis of StimGun technology

With further exploration and development of oil and gas wells, it is found that the unconventional oil-gas bed occupies a major proportion in gas reserves. However, it is difficult to obtain satisfactory control by using conventional perforation technology because of its characteristics of low pore, low permeability and compact lithology in the unconventional oil-gas bed. The StimGun tech (synergize compound perforation) is described as following: after the perforating gun is fired, propellant burns with high-energy gas produced. Then the high-energy gas enters the perforating hole and forms multi-path cracks around perforated hole, which connects with the natural cracks and improves the permeability of oil and gas bed. The application and advantage of StimGun are introduced. The Stimgun is successfully applied in Sichuan LG oilfield. It can control the fracture heights effectively and remove contamination formation with no water producing, and it is also a great help to increase productivity of the oil-gas bed with low permeability.     

THE MATHEMATICAL MODEL OF CARBURIZED MASS-TRANSFER AND ITS MEANINGS

This paper deals with the kinetics of carbon atoms transfer from gas phase to solid phase in gas carburizing. According to the kinetic equations of the chemical reactions on the solid surface, it is deduced that the carbon transfer quantity from gas phase to solid phase is in direct proportion to the difference of carbon activiries between gas phase and solid phase. Based on what is mentioned above, we set up the kinetic equation of carbon transfer from gas phase to solid phase, discussed the factors which affected the carbon transfer. It was known then that increasing the contents of carbon monoxide and hydrogen in gas phase could qu'icken the carbon transfer. On the other hand, proper oxidants, especially proper water, could quicken the carbon transfer.     

Simulation research on oxygen blast furnace ironmaking process

A system simulation mathematical model on oxygen blast furnace ironmaking process is established. Provided that the material composition and the values of necessary process parameters are given, the model can predict the consumptions of raw material, fuel and flux, the quantity and composition of slag, the quantities and components of all kinds of gases, etc. At the condition of 90% stack ore metallization, the calculated results of the model show that when more circulating gas are introduced into the stack, the heat controls the total gas for the stack ore reduction, while when more circulating gas are introduced into the hearth, the reductive components control the total gas for the stack ore reduction. At normal operations with coke rate fixed, the coal consumption linearly increases with the output top gas. When the coke rate is fixed at 200 kg, the minimum value of calculated coal rate is 200 kg or so.