Experimental Study on the Stick-slip Phenomenon of Intact Granite under Solid Confining Pressure

In this paper,compression tests of intact granite samples have been made in a triaxial testing machine with solid confining pressure.From the tests,the influences of confining pressure and loading rate(axial strain rate)on the deformation and fracture process of rock samples,on the stress drop and recurrence interval of stick-slip events,and on the geometric distribution of the main fracture have been studied.The experimental results show that the loading rate influences the stress drop and recurrence interval of stick-slip events greatly.At lower loading rates,the stress drop of stick-slip events is greater,their recurrence interval is longer and shows no regularity in distribution.When the loading rate goes higher,the stress drop will become smaller and the recurrence interval will tend to be constant and stick-slip events show a quasi-periodicity.At lower confining pressures and strain rates,the main fracture may evolve into 2 X-shaped conjugate shear faults; whereas at higher confining pressures

Pore-scale study of the pressure-sensitive effect of sandstone and its influence on multiphase flows

The pressure-sensitive effect on the pore structure of sandstone was investigated using X-ray computed micro-tomography and QEMSCAN quantitative mineral analysis. In a physical simulation study, we extracted the pore network model from digital cores at different confining pressures and evaluated the effect of pressure sensitivity on the multiphase displacement process. In both the pore network model and QEMSCAN scanning, the pore structure was observed to be damaged under a high confining pressure. Due to their different scales, the pores and throats exhibited inhomogeneous changes; further, the throats exhibited a significant variation compared to that exhibited by the pores. Meanwhile, the heterogeneity of the pore structure under the two aforementioned activities was aggravated by the elastic-plastic deformation of the pore structure.The pressure-sensitive effect increased the proportion of mineral particles, such as quartz(the main component of the core skeleton), and reduced the proportion of clay minerals. The clay minerals were originally attached to the pore walls or interspersed in the pores; however, as the pressure increased, the clay minerals accumulated in the pores resulting in blockage of the pores. While simulating the multiphase displacement process, increasing the confining pressure was observed to severely restrict the flowability of oil and water. This study promises to improve the efficiency of reservoir development in terms of oil and gas exploitation.

Comparison of electrochemical properties of atmospheric pressure plasma coatings for Al_2O_3-3TiO_2 and CoNiCrAlY in sea water

To improve the durability of underwater rotating products,the corrosion characteristics in harsh marine environment were evaluated through various electrochemical experiments on the Al2O3-3TiO2 and CoNiCrAlY coating layers by atmospheric pressure plasma spray coating process.By evaluating the corrosion resistance of these materials,their applicability to environmentally friendly power generation equipment such as blades of tidal current turbines was examined.According to the Tafel analysis for micro-areas including the coating layer,the coating/metal interlayer and the base metal,the Al2O3-3TiO2 coating layer and the CoNiCrAlY coating layer show markedly lower corrosion current density than the base metal.The corrosion current density of the CoNiCrAlY coating layer (9.75316×10-8A/cm2) is about 1.6 times more than that of the Al2O3-3TiO2 coating layer (6.13139×10-8A/cm2).

THE CENTRAL DISTRIBUTION OF ADRENOMEDULLIN AND ITS EFFECTS ON BLOOD PRESSURE AND HEART RATE IN RATS

The present study was designed to make certain whether there exists adrenomedullin (ADM) in the rat central nervous system and evaluated the hemodynamic actions of intracerebroventricular administration (ICVA) of human ADM[13-52]. By immunohistochemistry (ABC method),We found that there was a discrete localization of ADM-positive immunoreactivity in the rat central system including cerebral cortex,paraventricular tissues, hypothalamus, cerebella cortex, mesencephalon and medulla oblongata. By reverse transcription-polymerase chain reaction(RT-PCR) analysis, rat ADM mRNA was found to be expressed in rat brain. These above results of immunohistochemistry and RT-PCR suggest that ADM exists in the rat brain. We also found that centrally administered ADM[13-52]in a dose of 0.4 to 3. 2 nmol/kg provoked marked, prolonged and dosedependent increases in mean arterial blood pressure (MABP) and heart rate (HR). To clarify the mechanisms of the hemodynamic changes induced by centrally administered ADM [13-52]. the effect of centrally administered ADM [13-52] on renal sympathetic nerve activity (RSNA) was studied. The result showed that centrally administered ADM [13-52] ( 1. 6 nmol/kg) provoked a marked increase in RSNA .therefore .the increases in MABP and HR induced by centrally administered ADM [13-52]might be due to the stimulation of central sympathetic mechanism. In addtion,we also compared the relationship of activity and structure among the different fragments of ADM. In conclusion, ADMexists in the rat brain, and it may play an important role in the central control of cardiovascular system.

Diffusion coefficients of natural gas in foamy oil systems under high pressures

The diffusion coefficient of natural gas in foamy oil is one of the key parameters to evaluate the feasibility of gas injection for enhanced oil recovery in foamy oil reservoirs. In this paper, a PVT cell was used to measure diffusion coefficients of natural gas in Venezuela foamy oil at high pressures, and a new method for deter- mining the diffusion coefficient in the foamy oil was de- veloped on the basis of experimental data. The effects of pressure and the types of the liquid phase on the diffusion coefficient of the natural gas were discussed. The results indicate that the diffusion coefficients of natural gas in foamy oil, saturated oil, and dead oil increase linearly with increasing pressure. The diffusion coefficient of natural gas in the foamy oil at 20 MPa was 2.93 times larger than that at 8.65 MPa. The diffusion coefficient of the natural gas in dead oil was 3.02 and 4.02 times than that of the natural gas in saturated oil and foamy oil when the pressure was 20 MPa. However, the gas content of foamy oil was 16.9 times higher than that of dead oil when the dissolution time and pressure were 20 MPa and 35.22 h, respectively.

Experimental analysis of pressure characteristics of catalyst powder flowing down a cyclone dipleg

An experiment was carried out for investigating pressure behavior of catalyst powders, with a Sauter mean diameter of 63.6 μm, flowing downward in a cyclone dipleg with 150 mm inner diameter and 9000 mm high. Time mean pressure and time series of pressure fluctua- tions were measured at different axial positions in the dipleg with particle mass fluxes ranging from 50.0 to 385.0 kg m-2s t. The experimental results showed that the time mean pressure in the dipleg increased progres- sively from the top section to the bottom section. The experimental phenomena displayed that the fluidization patterns in the dipleg can be divided into two types on the whole, namely the dilute-dense coexisting falling flow and the dense conveying flow along the dipleg. In the dilute- dense coexisting falling flow, the dilute phase region was composed of a length of swirling flow below the inlet of dipleg and a dilute falling flow above the dense bed level. With increasing particle mass flux, the dilute-dense coex- isting falling flow was gradually transformed to be the dense conveying flow, and the exit pressure of the dipleg increased considerably. The pressure fluctuations were closely related to the flnidization patterns inside the dipleg. In the dilute-dense coexisting falling flow, the pressure fluctuations in the dilute flow region originated from par- ticle clusters, propagating downward as a pressure wave; however, the pressure fluctuations in the dense flow region originated from rising gas bubbles, propagating upward. When the dense conveying flow was formed in the dipleg,the pressure fluctuations originated mainly from instability of the feed and the compressed gas, propagating down- ward. The standard deviation of the pressure fluctuations indicated that the intensity of pressure fluctuations first increased and then decreased with increasing particle flux.

Research on New Testing Method and Instrument of Clothing Pressure

This paper discusses the formation of the fabric clothingpressure,the efforts of the human body and the impor-tance of the clothing pressure measurement.Several as-pects such as setting up the scientific and simple measur-ing method of the clothing pressure,the designing andmaking the measuring instruments are emphasized.Bymeans of experimental testing and analysis,some usefulresults can be derived from these works.

Modeling of fluid dynamics interacting with ductile fraction propagation in high pressure pipeline

This paper presents a computational model for the fluid dynamics in a fractured ductile pipe under high pressure. The pressure profile in front of the crack tip, which is the driving source of crack propagation, is computed using a nonlinear wave equation. The solution is coupled with a one dimensional choked flow analysis behind the crack. The simulation utilizes a high order optimized prefactored compact-finite volume method in space, and low dispersion and dissipation Runge-Kutta in time. As the pipe fractures the rapid depressurization take place inside the pipe and the propagation of the crack-induced waves strongly influences the outflow dynamics. Consistent with the experimental observation, the model predicts the expansion wave inside the pipe, and the reflection and outflow of the wave. The model also helps characterize the propagation of the crack dynamics and fluid flows around the tip of the crack.

Formation permeability evaluation and productivity prediction based on mobility from pressure measurement while drilling

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.

埕海1-1区二开244.5 mm套管防黏卡安全下入分析

大港油田埕海区块大位移井套管下入困难,卡套管问题频发,急需解决方案。针对大港油田埕海1-1区块近年来发生的卡套管事故进行了统计分析,发现卡钻机理以压差黏卡为主。结合压差黏卡机理,构建了基于管柱-泥饼接触模型的压差卡钻预测模型,并研究了解决方案。分析得出的通过减轻套管重量从而减少与井壁接触面积来预防黏卡的作用机理,在埕海1-1-XX井与埕海1-1-YY井上得到了应用,成功实现了该大位移井244.5 mm套管的安全下入,证明该防黏卡分析机理正确、技术可行。其中埕海1-1-XX井以漂浮2846 m打破中石油244.5 mm套管漂浮段长纪录,埕海1-1-YY井在中石油内部首次实现大位移井244.5 mm套管全漂浮下入。

圆柱和平面之间粘-滑接触分析

当圆柱和平面产生粘-滑接触时，在Hertz理论和Mindlin理论基础上，推导了平面内应力分量的计算公式．分析了平面内应力的分布，描述了应力分布的特点．x轴向应力在接触表面的导向边均为压应力，而在拖动边存在拉应力；最大拉应力和最大压应力均出现在接触表面，其中，最大拉应力存在于拖动边的边缘。而最大压应力存在于导向边．z轴向应力均为压应力，最大压应力出现在接触表面的接触中心邻近区域．第一主应力的最大拉应力出现在接触表面的拖动边边缘，而在导向边均为压应力．第三主应力均为压腹力，最大压应力出现在接触表面的导向边．剪应力、主剪应力和VonMises等效应力（当摩擦系数较小时）的最大值均出现在平面内部．因此，第一型裂纹的产生和扩展首先会发生在拖动边的边缘;而塑性滑动开始首先会出现在接触体内，然后扩展到接触表面．这些将为研究接触变形和接触体的失效提供理论基础．

Y521-110FQ防卡注水封隔器的研制及应用

针对Y521封隔器在文明寨油田应用中存在的若干问题,研制了Y521-110FQ防卡注水封隔器。该封隔器主要由上接头、油压活塞、洗井活塞、水力锚、内外中心管、压缩环、摩擦及卡瓦装置、下接头等组成。洗井活塞采用油压和下压双重关闭设计,最大限度地满足了注水和停注时不同压力系统下洗井机构密封的要求;解封时洗井活塞强制开启,使上、下压力系统连通,解决了上部高压导致解封困难的问题。文明寨油田16口注水井的应用效果表明,该封隔器结构合理,原理可靠,能提高管柱分层注水成功率,提高封隔器密封性能,满足高温高压、层间差异大井的分注要求。

高密度水包油钻井液在磨005-H8井的应用

以川中磨溪构造嘉陵江组为目的层的水平井,在钻井过程中均发生了不同程度的压差粘附卡钻,部分井除多次发生高压差卡钻外,还发生了下套管不到位等技术难题。针对这些难题,研制了一套高密度弱凝胶、无土相水包油钻井液体系。通过在川中磨005-H8井的应用表明,该体系具有较好的抗盐、抗钙能力,润滑性接近油包水钻井液体系,在起钻接单根与起下钻过程中摩阻较小,体系的性能十分稳定,维护处理简单,现场操作性强。

DH1-H3深阶梯水平井钻井液技术

DH1-H3井是位于塔里木盆地塔北隆起东河塘断裂构造带东河1背斜的一口超深阶梯水平井,完钻井深为6326 m。该井深、井眼大且长裸眼,油层压力系数低、存在高压差,钻井过程中的潜在事故、复杂隐患多,该区的1口水平井因在二开大井眼无法解决"流变性与压耗"的矛盾,被迫提前中途完钻;另1口水平井因卡钻而侧钻。该井通过优选正电胶-聚合物-聚磺体系,优化配方及维护处理方案,保证了该井的顺利完成并节约钻井周期80多天。提出,采用强封堵、强润滑,结合"无故障及间歇"钻井的思路,可解决高压差、枯竭产层的压差卡钻问题;合理复配使用正电胶与高分子量聚合物,是解决抑制与分散、循环压耗与岩屑携带的关键。

动态高压微射流协同糖基化处理对β-乳球蛋白热稳定性和结构的影响

采用动态高压微射流(dynamic high pressure microfluidization,DHPM)协同葡聚糖糖基化处理对β-乳球蛋白(β-lactoglobulin,β-Lg)进行改性,研究其热稳定性和结构的变化。结果表明,β-Lg的峰顶温度为73. 48℃,经DHPM不同压力(40、80、120 MPa)处理后,其热稳定性先下降后上升,但经DHPM协同糖基化处理后,其热稳定性均呈上升趋势。理化分析结果显示,80 MPa DHPM协同糖基化处理的β-Lg具有最低的游离氨基酸含量(2. 20 mg/m L)和最高的褐变程度(A294=1. 092,A420=0. 062),说明DHPM预处理可以促进β-Lg-葡聚糖的糖基化反应,且80 MPa为最佳处理压力。结构分析表明,DHPM处理可明显提高β-Lg的表面疏水性和自由巯基含量,降低其内源荧光强度,使其发生二级结构变化。经DHPM协同糖基化处理后,β-Lg的表面疏水性有所降低,但仍高于天然β-Lg的表面疏水;自由巯基含量呈现先降低后升高趋势,在80 MPa时明显高于天然β-Lg,内源荧光强度随着压力的增加呈先降低后上升的趋势,但均明显低于天然β-Lg的内源荧光强度。因此,DHPM 80 MPa预处理样品具有最高的热稳定性和糖基化程度,且β-Lg的糖基化程度越高,其热稳定性越好。

Hypersonic boundary-layer transition on a flared cone

Transition on a flared cone with zero angle of at- tack was studied in our newly established Mach 6 quiet wind tunnel （M6QT） via wall pressure measurement and flow visualization. High-frequency pressure transducers were used to measure the second-mode waves＇ amplitudes and frequencies. Using pulsed schlieren diagnostic and Rayleigh scattering technique, we got a clear evolution of the second-mode disturbances. The second-mode waves exist for a long distance, which means that the second-mode waves grow linearly in a large region. Strong Mach waves are radiated from the edge of the boundary layer. With further development, the second-mode waves reach their maximum magnitude and harmonics of the second-mode instability appear. Then the disturbances grow nonlinearly. The second modes become weak and merge with each other. Finally, the nonlinear interaction of disturbance leads to a relatively quiet zone, which further breaks down, resulting in the transition of the bound- ary layer. Our results show that transition is determined by the second mode. The quiet zone before the final breakdown is observed in flow visualization for the first time. Eventual transition requires the presence of a quiet zone generated by nonlinear interactions.

Modeling of flow of oil-in-water emulsions through porous media

Formation and flow of emulsions in porous media are common in all enhanced oil recovery tech- niques. In most cases, oil-in-water （O/W） emulsions are formed in porous media due to oil-water interaction. Even now, detailed flow mechanisms of emulsions through porous media are not well understood. In this study, variation of rate of flow of O/W emulsions with pressure drop was studied experimentally, and rheological pa- rameters were calculated. The pressure drop increases with an increase in oil concentration in the O/W emulsion due to high viscosity. The effective viscosity of the emulsion was calculated from the derived model and expressed as a function of shear rate while flowing through porous media. Flow of O/W emulsions of different concentrations was evaluated in sand packs of different sand sizes. Emulsions were characterized by analyzing their stability, rheological properties, and tem- perature effects on rheological properties.

东河1-H18C井钻井复杂情况分析

东河1-H18C井是位于塔里木东河油田东河1区块的一口开窗侧钻定向井。该井钻井工程的难点是:同一裸眼内存在压力系数相差较大的地层,极易造成粘卡;井斜角达到57°,Ф152.4 mm井眼下Ф127 mm尾管,环空间隙小,固井风险大。实钻过程中发生卡钻和固井憋高压事件。通过对钻井工程难点的细致分析,从中找出导致事件发生的原因,从而采取必要的措施,在今后的钻井生产中加以避免,可对现场技术工作起到借鉴作用。

Topology optimization of 3D structures with design-dependent loads

Topology optimization of continuum structures with design-dependent loads has long been a challenge. In this paper, the topology optimization of 3D structures subjected to design-dependent loads is investigated. A boundary search scheme is proposed for 3D problems, by means of which the load surface can be identified effectively and efficiently, and the difficulties arising in other approaches can be overcome. The load surfaces are made up of the boundaries of finite elements and the loads can be directly applied to corresponding element nodes, which leads to great convenience in the application of this method. Finally, the effectiveness and efficiency of the proposed method is validated by several numerical examples.

Mathematical Model of Steady State Operation in Jet Pipe Electro-Hydraulic Servo Valve

Jet pipe electro-hydraulic servo valve is the heart of feedback control systems,and it is one of the mechatronic components used for precision flow control application.It consists of several precision and ddicate components.The performance of the jet pipe servo valve depends on many parameters.During the developmental stage,it is very difficult to ascertain the function parameters.The steady-state analysis of jet pipe electro-hydraulic servo valve has been made to simulate its fluid characteristics （flowin,flow-out,leakage flow,recovery or load pressure,etc.） by mathematical modeling.Theoretical model was conducted on various affecting parameters on the pressure,the main flow rate of fluid,or leakage flow through the receiver holes.The major parameters studied are jet pipe nozzle diameters,receiver hole diameters,angle between the two centre-lines of receiver hole,nozzle offset,and nozzle stand-of distance.In this paper the research is important to determine and optimize the structural parameters of jet pipe servo valve.Thus,equations of the pressure and flow characteristics are set up and the optimal structural parameters of jet pipe are established.