油气集输站场带压热开孔技术应用

随着油气田不断开发和增产,老旧站场面临着维修改造及改扩建的问题,为避免影响生产作业,需要用到带压开孔技术。结合带压热开孔工艺的技术要点及安全分析,介绍了带压热开孔常用的单开孔、单封堵和封堵不停输3种工艺在非洲某油田站场改扩建工程中的应用场景。根据站场内不同的情况对3种热开孔技术的组合使用,可以实现复杂情况下站内管线不停产改造的目的。

管线带压开孔技术分析与海外工程实践

结合作者在沙特阿美项目的实际应用,对带压开孔技术进行介绍,针对其技术特点、流程、管控程序、要点及难点做一个技术拓展与探讨,供相关类似油气工程借鉴与参考。

高速远程滑坡摩擦生热减阻机理研究现状及展望

高速远程滑坡基底层与其下伏层之间存在复杂多变的摩擦生热过程和作用,由此将产生一系列摩擦生热现象及其高速远程滑坡运动的减阻机理。这是国内外最近几十年来滑坡动力学研究领域广泛关注的重要科学问题。本文对滑坡摩擦生热减阻机理研究的发展历程与研究现状进行了述评。首先,回顾了高速远程滑坡摩擦生热现象的研究历史,重点介绍了滑坡摩擦岩术语的由来与发展历程;其次,根据摩擦生热减阻产物及过程,基于最新报道的全球典型实例,分别介绍了热熔融、热孔压、热分解与热润滑4类滑坡减阻机理的研究现状;第三,提出了下一步研究应重点关注的关键科学问题,亦即:在野外进一步发现和准确鉴定滑坡摩擦生热减阻的地质证据,在室内强化摩擦生热相关参数的定量化动态实时监测与表征,并进行多过程多场耦合的摩擦生热减阻机理研究;最后,本文对高速远程滑坡摩擦生热减阻机理的发展趋势进行了讨论与展望。

Preparation of Al-doped ZnO sputter target by hot pressing

Al-doped ZnO （AZO） target was prepared by hot pressing using ZnO and Al2O3 powder in mass ratio of 98：2.The effects of hot pressing conditions including temperature,pressure and preserving time on relative density were investigated.Pore evolution and phase structure change during densification process were studied.The results show that AZO target with super high relative density of 99% was prepared by two-stage hot pressing method under pressure of 35MPa,temperature of 1 050℃ and 1 150℃ with preserving time of 1 h,respectively.At temperature around 1 050℃,the number of isolated pore wasminimum.At temperature lower than 900℃,there existed Al2O3 phase.At temperature higher than 1 000℃,ZnAl2O4 phase was generated and its content was increased with temperature increasing.Hot pressing method had the advantage over pressureless sintering that the content of ZnAl2O4 was lower and sintering temperature could be also lower.With increasing the hot pressing temperature and preserving time,the electric resistivity of AZO target decreased greatly.A low resistivity of 3 10-3 cm was achieved under the temperature of 1 100℃,pressure of 35MPa and preserving time of 10 h.

APPLICATION OF HOT-PRESS SINTERING TECHNIQUE TO EXPLOSIVE CHARGE LINER OF PETROLEUM PERFORATION BULLET

A new method for manufacturing explosive charge liner of petroleum perforation bullet, using hot press sintering technique, has been introduced in the paper. The sintering process of making explosive charge liner has been investigated. The mechanical test and SEM analysis indicate that the property of the liner produced by the process is satisfied.

Pore structure of unidirectional solidified lotus-type porous silicon

Lotus-type porous silicon with elongated pores was fabricated by unidirectional solidification under pressurized hydrogen. Porosity, pore diameter, and pore length can be adjusted by changing solidification speed and hydrogen pressure. The porosity of the ingot is nearly constant under different solidification speeds, but decreases with the increase of hydrogen pressure. The overall porosities of ingots fabricated at different hydrogen pressures were evaluated through a theoretical model. Findings are in good agreement with experimental values. The average pore diameter and pore length increase simultaneously while the average pore aspect ratio changes slightly with the decreases of solidification speed and hydrogen pressure. The average pore length is raised from 7 to 24 mm and the pore aspect ratio is raised from 8 to 20 respectively with the average pore diameter promoted by about 0.3 mm through improving the superheat degree of the melt from 200 to 300 K.

Hot shear deformation constitutive analysis of fine-grained ZK60 Mg alloy sheet fabricated via dual equal channel lateral extrusion and sheet extrusion

Dual equal channel lateral extrusion(DECLE)process with various passes followed by sheet extrusion process was performed to produce fine-grained ZK60 alloy sheets.The coarse grain structure of the annealed sample after applying sheet extrusion(size:68μm)changed to fine grains of 6.0 and 5.2μm after 3 and 5 passes of DECLE and following extrusion.The hot shear deformation behavior of samples was studied by developing constitutive equations based on shear punch test(SPT)results.SPT was carried out in the temperature range of 200−300℃ and strain rate range of 0.003−0.33 s^(–1).The activation energy of 125−139 kJ/mol and the stress exponent of 3.5−4.2 were calculated for all conditions,which indicated that dislocation creep,controlled by dislocation climb and solute drag mechanism,acted as the main hot deformation mechanism.It was concluded that material constants of n and Q are dependent on the microstructural factors such as grain size and second phase particle fraction,and the relationship of which was anticipated using a 3D surface curve.Moreover,the similar strong basal texture of extruded sheets gave rise to the same deformation mechanisms during SPT and similar n and Q values for ZK60 alloy.

Effects of Heat Softening on Initiation of Landslides

Effects of heat softening on the initiation of slide surface(shear banding) in clayey slopes during fast deformation were discussed.Controlling equations considering heat,pore pressure and mechanical movement were presented.By perturbation method,the instability condition of localized zone(i.e.criterion for initiation of shear banding) for thermal related soils,such as clayey slope,was obtained.It is shown that slide surface initiates once the thermal-softening effects overcome the strain-hardening effects whether it is adiabatic or not.Without strain hardening effects,strain rate hardening obviously plays a role in initiation of shear band.During initiating process,heat is trapped inside the shear band,which leads rapidly to a pore pressure increase and fast loss of strength.The localized shear strain is concentrated in a narrow zone with a width of several centimeters at most and increases fast.This zone forms the sliding surface.Temperature can increase more than 2?C,pore pressure can increase 160% in about 0.1s inside this zone.These changes cause the fast decrease in friction-coefficient by about 36% over the initial value.That is how shear band initiated and developed in clayey slopes.

Simulation of pressure effects on hot isostatic pressing of stainless steel powder

To investigate the effects of pressure on the hot isostatic pressing(HIP) process of a stainless steel powder,density distribution and deformation of the powder at four different applied pressure levels were predicted and compared by using finite element method(FEM).Constitutive relations of porous compacts during HIP process were derived based on the yield criterion of porous metal materials.Thermo-mechanical coupling calculations were carried out by the MSC.Marc.Densification mechanisms were studied through evolutions of relative density,equivalent plastic strain and equivalent viscoplastic strain rate for compacts.The simulation results were also compared with experimental data.The results show that the densification rate and final density of compacts increase dramatically with the increase in the applied pressure level when it is below 100 MPa during HIP process,and the creep for compacts evolves into steady stage with the improvement of density.

Change in the Pore Structure of Carbon-Carbon Composites during Successive Stages of High-Pressure Impregnation and Heat Treatment

Pore structure of C/C （Carbon-Carbon） composite after several stages of pitch impregnation under the high pressure and heat treatment was investigated by means of low temperature nitrogen adsorption and the standard contact porosimetry. Total pore volume, pore size distribution and specific surface area were calculated for samples of composite after several successive stages of treatment. The radius of pores presented in the material changes from 1 nm to 90 tam. Total pore volume and specific surface area both decrease after successive stages of pitch impregnation under the pressure, whereas heat treatment up to 1,750 ℃ and 2,000 ℃ leads to creation of some porous space and pore volume expansion. The bulk porosity of C/C composite comes down from 33.7% to 13.7% after the serial stages of treatment and the specific surface area is reduced by half compared to the initial material.

LARGE－TIME BEHMIOR OF SOLUTIONS FOR THE SYSTEM OF COMPRESSIBLE ADIABATIC FLOW THROUGHPOROUS MEDIA

Consider the systemwhich can be used to model the adiabatic gas flow through porous media. Here v is specific volume, u denotes velocity, s stands for entropy, p denotes pressure with pv <0 for v >0. It is proved that the solutions of (1) tend to those of the following nonlinear parabolic equation time-asymptotically:

ASYMPTOTIC BEHAVIOR OF SOLUTIONS TO THE COMPRESSIBLE ADIABATIC FLOW THROUGH POROUS MEDIA WITH BOUNDARY EFFECTS

The initial boundary value problems (IBVP) for the system of compressible adiabatic flow through porous media and the IBVP for its corresponding reduced system through Darcy’ laws on [0, 1] x [0, +] are considered respectively. The global existence of smooth solutions to the IBVP problems for two systems are proved, and their large-time behavior is analyzed. The time-asymptotic equivalence of these two systems are investigated, the decay rate of the difference of solutions between these two systems are shown to be determined explicitly by the initial perturbations and boundary effects. It is found that the oscillation of the specific volume can be cancelled by that of entropy, i.e., the oscillation of the specific volume and entropy is not required to be small.

Experimental simulation of gas hydrate decomposition in porous sediment

Gas hydrate decomposition in sediments involves complicated multiphase flow and heat and mass transfer processes because of heat absorption by solid hydrates. Factors affecting gas hydrate decomposition in sediments include sediment type, mineral composition, pore size distribution, particle size, pore water composition, hydrate saturation distribution, initial formation pressure and temperature and cement characteristics. In this paper, experimental simulations of gas hydrate decomposition are carried out on an artificial core to investigate the effects of initial pressure and temperature, particle size and pore size. The experiments show that the characteristics of gas hydrate decomposition in sediments differ completely from those in a pure water system. The decomposition rate of hydrate sediments increases with the initial pressure increasing and decreasing temperatures. Furthermore, the decomposition rate of hydrate sediments decreases with decreasing particle size and increasing pore size.