Wellbore Cleaning Degree and Hydraulic Extension in Shale Oil Horizontal Wells

The efficient development and exploitation of shale oil depends on long-distance horizontal wells. As the degreeof cleaning of the wellbore plays a key role in these processes, in this study, this problem is investigated experimentallyby focusing on the dimensionless cuttings bed height. A method is proposed to calculate the horizontalwellhydraulic extension taking into account the influence of the wellbore cleaning degree on the wellborepressure distribution and assess the effect of a variety of factors such as the bottom hole pressure, the circulatingpressure drop, the drilling pump performance and the formation properties. The analysis shows that the hydraulicextension of horizontal wells decreases with an increase in the cuttings bed height, and the higher the displacementof drilling fluid, the faster the hydraulic extension declines. The annular pressure drop of the horizontalsection increases with the increase of the cuttings bed height, resulting in a higher bottom-hole pressure. Severalarguments are provided to guide the safe drilling of shale oil horizontal wells and overcome the limits of currenttechnological approaches.

Rules Governing Pressure Distribution for a Traveling Charge Under the Condition of Lagrange Hypothesis

Aim To study the rules governing pressure distribution of traveling charge under the condition of Lagrange hypothesis. Methods\ The study is based on the laws of conservation of momentum and energy. Results\ The gas flow velocity distribution formula at the back of a projectile and the momentum equation of a traveling charge are deduced, and rules governing their pressure distribution under the Lagrange hypothesis conditions are established. The pressure distribution of a traveling charge is compared with that of a conventional charge. Conclusion\ The pressure distribution in the bore of a traveling charge can be accurately predicted. A parabolic pressure distribution type is revealed.

The Pairing Analysis Improvement of Magnetized Structure in Electromagnetic Bulging Process in Case of Tube with Field Shaper

In the current practical science, the accuracy in the formability of metal alloys being the goal when using electromagnetic forming (EMF) technology, which is a high-speed processing technology that uses Lorentz forces to achieve plastic deformation of sheet metal;according to the previous analysis, the results have shown that in most cases, the Lorentz force acting on the workpiece (metal) is not uniform, there are uneven axial deformations of the metal plates which prevent the rapid advancement of today’s technology. In this article, we presented some advanced analyzes which will lead us to improve the technical solution for the problems of non-uniform axial deformations of the metals in the traditional tube electromagnetic forming technology (EMF). A field shaper is used as a practical forming tool to influence the magnetic field and magnetic pressure distribution, thereby improving the forming ability and result during the electromagnetic forming (EMF) process and we see that induced eddy current control is realized by changing the structural parameters of the magnetic field shaper;which improves the strength and controllability of the magnetic force that acts on the workpiece;thereby a greater radial magnetic pressure can be achieved with field shaper than the case without it;the field shaper regulates the electromagnetic force, the distribution of the magnetic pressure decreases, and the uniform force area of the tube increases which effectively enhances the uniform range of the pipe electromagnetic bulging and the electromagnetic induction coupling between the coil and the metallic workpiece is generally required to produce the Lorentz forces. Using COMSOL Multiphysics® simulation software helped us to accurately represent the real world, simulating multiple physical effects that happened in this model during the process.

Improved finite difference method for pressure distribution of aerostatic bearing

An improved finite difference method （FDM）is described to solve existing problems such as low efficiency and poor convergence performance in the traditional method adopted to derive the pressure distribution of aerostatic bearings. A detailed theoretical analysis of the pressure distribution of the orifice-compensated aerostatic journal bearing is presented. The nonlinear dimensionless Reynolds equation of the aerostatic journal bearing is solved by the finite difference method. Based on the principle of flow equilibrium, a new iterative algorithm named the variable step size successive approximation method is presented to adjust the pressure at the orifice in the iterative process and enhance the efficiency and convergence performance of the algorithm. A general program is developed to analyze the pressure distribution of the aerostatic journal bearing by Matlab tool. The results show that the improved finite difference method is highly effective, reliable, stable, and convergent. Even when very thin gas film thicknesses （less than 2 Win）are considered, the improved calculation method still yields a result and converges fast.

Investigation on fracture models and ground pressure distribution of thick hard rock strata including weak interlayer

Dynamic disasters,such as rock burst due to the breaking of large area stiff roof strata,are known to occur in the hard rock strata of coal mines.In this paper,mechanical models of the fracturing processes of thick hard rock strata were established based on the thick plate theory and numerical simulations.The results demonstrated that,based on the fracture characteristics of the thick hard rock strata,four fracture models could be analyzed in detail,and the corresponding theoretical failure criteria were determined in detail.In addition,the influence of weak interlayer position on the fracture models and ground pressure of rock strata is deeply analyzed,and six numerical simulation schemes have been implemented.The results showed that the working face pressure caused by the independent movement of the lower layer is relatively low.The different fracture type of the thick hard rock strata had different demands on the working resistance of the hydraulic powered supports.The working resistance of the hydraulic powered supports required by the stratified movements was lower than that of the non-stratified movements.

Side abutment pressure distribution by field measurement

Given the 7123 working face in the Qidong Coal Mine of the Wanbei Mining Group, nine dynamic roof monitors were installed in the crossheading to measure the amount and velocity of roof convergence in different positions and at different times and three steel bored stress sensors were installed in the return airway to measure rock stress at depth. On the basis of this arrange- ment, the rule of change of the distribution of the side abutment pressure with the advance of the working face and movement of overlying strata was studied. The rule of change and the stability of rock stress at depth were measured. Secondly, the affected area and stability time of the side abutment pressure were also studied. The results show that: 1) During working, the face advanced distance was from 157 m to 99 m, the process was not effected by mining induced pressure. When the distance was 82 m, the posi- tion of peak stress was 5 m away from the coal wall. When the distance was 37 m, the position of peak stress away from the coal wall was about 15 m to 20 m and finally reached a steady state; 2) the time and the range of the peak of side rock pressure obtained from stress sensors were consistent with the results from the dynamic roof monitors; 3) the position of the peak pressure was 25 m away from the coal wall.

Experimental Study on the Distribution of Velocity and Pressure near a Submarine Pipeline

As a transport means of oil and gas the submarine pipeline has many merits, such as continuous delivery, large conveying capacity, convenient management, etc. A tube was chosen in our study to simulate the submarine pipeline in the experiments. A high accuracy instrument ADV and high precision point-type pressure sensors were used to measure the parameters of the flow field, including the pressure distribution, velocities at seven cross sections near the submarine pipeline with five different clearance ratios, and twelve dynamic pressure values around the pipeline. The pressure distributions and velocity changes around the pipe under dif- ferent flow velocities and clearance ratios were analyzed. These results might be useful for further study of submarine pipeline ero- sion and protection.

BODY PRESSURE DISTRIBUTION OF AUTOMOBILE DRIVING HUMAN MACHINE CONTACT INTERFACE

Aiming at the fatigue and comfort issues of human-machine contact interface in automobile driving and based on physiological and anatomical principle, the physiological and biochemical process of muscles and nerves in the formation and development of fatigue is analyzed systematically. The fatigue-causing physiological characteristic indexes are mapped to biomechanical indexes like muscle stress-strain, the compression deformation of blood vessels and nerves etc. from the perspective of formation mechanism. The geometrical model of skeleton and parenchyma is established by applying CT-scanned body data and MRI images. The general rule of comfort body pressure distribution is acquired through the analysis of anatomical structure of buttocks and femoral region. The comprehensive test platform for sitting comfort of 3D adjustable contact interface is constructed. The test of body pressure distribution of human-machine contact interface and its comparison with subjective evaluation indicates that the biomechanical indexes of automobile driving human-machine contact interface and body pressure distribution rule studied can effectively evaluate the fatigue and comfort issues of human-machine contact interface and provide theoretical basis for the optimal design of human-machine contact interface.

Empirical-analytical method for evaluating the pressure distribution in the hard coal seams

At present, numerical modelling of distributions of many rock mass characteristics plays more and more important role in many geomechanical questions. In the issues related to seismic and rockburst hazards, the analyses of distributions of stress component values in the rock strata are performed, similarly as those of deformation parameters of the strata. To do this, commercial computer programs are used which function on the basis of the finite element-, separate element-, finite difference-, boundary element methods, or individually designed computer programs. They enable to obtain information, unattainable with other methods, being of importance for further concluding on those hazards. The programs based on applying those methods have contributed to important progress and development of science in the domain of analyzing and predicting the hazards. To this end, the commercial computer programs are used that are based on the methods of: finite elements, separate elements, finite differences, boundary elements, etc., or on individually developed computer programs. They enable to obtain information, unavailable using other methods, being of vital importance for further concluding on these hazards. The programs based on these methods have contributed to essential progress and development of science in the field of analysing and predicting the hazards. Apart from their obvious advantages, they have many drawbacks that hinder their practical, routine application. To allow making these type of analyses, without the necessity of constructing complicated models and knowing the detailed geomechanical parameters of rocks, together with laborious computation using a high-rank computer hardware, an analytical-empirical method has been developed at Central Mining Institute, Poland, to make prediction (modelling) of the distribution of pressure values (vertical component of stress) in SIGMAZ coal seams. It is based on geophysical measurements, generalized for the conditions of the Upper Silesia Coal Basin, of disturbing effect of the mining edge and tectonic faults on the state of stress. The paper presents methodological and programming assumptions of the method. The scope of its application has been discussed, and results of demonstration analyses for Polish hard coal mines presented. There have been also given the advantages of the method in relation to classical numerical methods.

A METHOD OF CALCULATING PRESSURE DISTRIBUTION OF PERIODIC PULSATION FLUID TRANSPORTED IN PIPING NETWORK

The pressure pulsation induced by the pumped periodic pulsation fluid is the main factor of causing fluid resonance and stimulating pipelines vibrations and noise. In order to reduce the faults caused by the vibrations of pipelines, two aspects have been researched: one is to develop high quality filters, weaken and restrain the crest of pulsation pressure; the other is to design structural parameters of the piping network and eliminate the fluid resonance. Both need calculating the pressure pulsations of different structural parameters and frequencies, and knowing the amplitude frequency. In this paper the stiffness matrix technique is used for treating the coupling of subsystems of pipelines and calculating the pressure distribution of the piping network and it is tested by simulation and experiments.

An Experimental Study on the Pressure Distribution in Horizontal Gas Wells

Laboratory experiments have been carried out to study the fluid flow in the wellbore of a horizontal gas well during the production process.The related pressure distribution has been determined considering different cases(different inflow media,different perforation opening methods and different liquid holdup).It has been found that the larger the fluid flow rate,the greater the pressure changes in the wellbore under the same hole opening mode.The uniformity of the perforation opening method was also an important factor affecting the magnitude of the wellbore pressure change.The liquid holdup also affected the pressure distribution,especially when the gas volumetric flow rate exceeded 200 m3/h.Comparison of the outcomes of the present experimental study with the predictions of a theoretical model available in the literature has provided a relative error smaller than 20%.

MATHEMATIC MODEL AND ANALYTIC SOLUTION FOR CYLINDER SUBJECT TO UNEVEN PRESSURES

According to the inverse solution of elasticity mechanics, a stress function is constructed which meets the space biharmonic equation, this stress functions is about cubic function pressure on the inner and outer surfaces of cylinder. When borderline condition that is predigested according to the Saint-Venant＇s theory is joined, an equation suit is constructed which meets both the biharmonic equations and the boundary conditions. Furthermore, its analytic solution is deduced with Matlab. When this theory is applied to hydraulic bulging rollers, the experimental results inosculate with the theoretic calculation. Simultaneously, the limit along the axis invariable direction is given and the famous Lame solution can be induced from this limit. The above work paves the way for mathematic model building of hollow cylinder and for the analytic solution of hollow cvlinder with randomly uneven pressure.

Wave Pressure Distribution over the Breast Wall of Mound Breakwater of Small Ports

In this paper, the mechanism of the interaction between the breast wall of mound breakwater and waves is expounded, then some new views and the law of variation of horizontal and vertical wave pressure over the breast wall are put forward. The results of this study have been adopted in the Specifications of Fishery Harbour Breakwater by the Ministry of Agricultures.

Pressure distributions generated by vaporizing metal foils

The pressure distributions generated by vaporizing metal foils were studied.An analytical model which described the dynamic mechanical behavior of a rectangular plate under an impulsive loading was introduced.The formed parts of free bulging tests were analyzed using the optical measurement system.Two measurement methods for pressure distributions were introduced and compared.Both the perforated sheet forming test and the pressure film were found to be effective method to measure pressure distributions.The cost of perforated sheet forming test was cheap and the pressure film was easy to operate.Three different pressure distributions were measured and discussed,namely single pressure distribution,tailored pressure distribution and double-direction pressure distribution.These three pressure distributions could be applied in different metal forming processes.

Calculating Method and Verification of Wave Pressure Distribution on the Breast Wall of Mound Breakwater

In this paper, the calculating charts and formulae about wave pressure on the breast wall are derived with seven parameters on the basis of physical model study. The verification shows that the charts agree with the example, and are adopted in the Specifications of Fishery Harbours Breakwater by the Ministry of Agricultures.

Pressure distribution of combining center cavity slipper for axial piston pump

In order to improve lubricating characteristics of slippers in an axial piston pump, the combining center cavity slipper approach was proposed based on slipper shape and moving characteristic. The cylindrical coordinate was used in the lubricant area and mesh was made. The blockweight approach was implemented to deal with non-coincidence of mesh and shallow recess border in numerical method. The finite control volume method was applied in calculating pressure distribution. The flow conservation equation and film thickness model were resolved through Gauss-Siedel relaxation iteration. The calculation and analysis results indicate that compared to the slipper （1） slip- per pressure distribution is improved; （2） hydrodynamic pressure of the combining slipper is greatly increased; （3） inclining degree is greatly reduced; （4） negative pressure in lubricant film disappear. So the combining center cavity slipper is lubricated better.

Study on Pressure Coefficient Distribution of the Airship Zhiyuan-1

A wind tunnel tests with different configurations,pitch and yaw angles were performed to study the wind load characteristics of the rigid model of the airship Zhiyuan-1. The rigid model was aimed to simulate a technical demonstrating stratospheric airship named Zhiyuan-1 according to the similarity principle of geometric and Reynolds number. Based on the results of wind tunnel test,the features of pressure coefficient distributions on the surface of the airship were described. It was indicated that the fins and the gondola of airship hardly have the effect on the pressure distribution on the surface of airship,but have obviously effect on the local areas near the fins and the gondola.

Textile-Based Capacitive Pressure Distribution Measurement System for Human Sitting Posture Monitoring

Flexible pressure monitoring device can help correct the sitting posture and prevent health problems(e.g.,deformity of spinal column and musculoskeletal disease).Currently,most measurement systems hinder their wide applications owing to the high cost or low accuracy.In this study,a flexible sitting pressure measurement system was proposed based on a textile-based capacitive pressure sensor array in order to measure sitting pressure distribution simply and conveniently.The capacitive pressure sensor array is sandwich structure composed of a high-density sponge layer and two electrode array fabrics,which possesses high resolution(2.26 sensors/cm2),high sensitivity(0.701 kPa-1)and fast response(≤35 ms).It is worth noting that the raw materials of the sensing fabric include commercialized copper sheets and polyester yarns.The as-prepared pressure measurement system can accurately measure the pressure distribution nephogram for sitting posture analysis.The sitting pressure of 10 volunteers was measured and six types of posture were distinguished clearly.

Pressure Distribution Characters of Flow Field around High-Speed Train

Based on incompressible viscous fluid Navier-stokes equation and k-ε 2-equations turbulent model, an investigation on 3D turbulent flow field around four kinds of train models has been made by finite element method. From the calculation, the pressure distribution characters of now field around high-speed trains have been obtained. It is significant for strength design of the high-speed train body, for resisting wind design of the facilities beside the high-speed railways and for determining the aerodynamic force of induced air to the human body near the railways.

Expressions of the radius and the surface tension of surface of tension in terms of the pressure distribution for nanoscale liquid threads

The expressions of the radius and the surface tension of surface of tension Rs and γs in terms of the pressure distribution for nanoscale liquid threads are of great importance for molecular dynamics （MD） simulations of the interfacial phenomena of nanoscale fluids; these two basic expressions are derived in this paper. Although these expressions were derived first in the literature[Kim B G, Lee J S, Han M H, and Park S, 2006 Nanoscale and Microscale Thermophysical Engineering, 10, 283] and used widely thereafter, the derivation is wrong both in logical structure and physical thought. In view of the importance of these basic expressions, the logic and physical mistakes appearing in that derivation are pointed out.