A new and reliable model for predicting methane viscosity at high pressures and high temperatures

In recent years, there has been an increase of interest in the flow of gases at relatively high pressures and high temperatures. Hydrodynamic calculation of the energy losses in the flow of gases in conduits, as well as through the porous media constituting natural petroleum reservoirs, requires knowledge of the viscosity of the fluid at the pressure and temperature involved. Although there are numerous publications concerning the viscosity of methane at atmospheric pressure, there appears to be little information available relating to the effect of pressure and temperature upon the viscosity. A survey of the literature reveals that the disagreements between published data on the viscosity of methane are common and that most investigations have been conducted over restricted temperature and pressure ranges. Experimental viscosity data for methane are presented for temperatures from 320 to 400 K and pressures from 3000 to 140000 kPa by using falling body viscometer. A summary is given to evaluate the available data for methane, and a comparison is presented for that data common to the experimental range reported in this paper. A new and reliable correlation for methane gas viscosity is presented. Predicted values are given for temperatures up to 400 K and pressures up to 140000 kPa with Average Absolute Percent Relative Error （EABS） of 0.794.

Modeling viscosity of methane,nitrogen,and hydrocarbon gas mixtures at ultra-high pressures and temperatures using group method of data handling and gene expression programming techniques

Accurate gas viscosity determination is an important issue in the oil and gas industries.Experimental approaches for gas viscosity measurement are timeconsuming,expensive and hardly possible at high pressures and high temperatures(HPHT).In this study,a number of correlations were developed to estimate gas viscosity by the use of group method of data handling(GMDH)type neural network and gene expression programming(GEP)techniques using a large data set containing more than 3000 experimental data points for methane,nitrogen,and hydrocarbon gas mixtures.It is worth mentioning that unlike many of viscosity correlations,the proposed ones in this study could compute gas viscosity at pressures ranging between 34 and 172 MPa and temperatures between 310 and 1300 K.Also,a comparison was performed between the results of these established models and the results of ten wellknown models reported in the literature.Average absolute relative errors of GMDH models were obtained 4.23%,0.64%,and 0.61%for hydrocarbon gas mixtures,methane,and nitrogen,respectively.In addition,graphical analyses indicate that the GMDH can predict gas viscosity with higher accuracy than GEP at HPHT conditions.Also,using leverage technique,valid,suspected and outlier data points were determined.Finally,trends of gas viscosity models at different conditions were evaluated.

Structures and Low Temperature Magnetic Anomalies of High Pressure RE_2CuO_4

A series of oxygen-doped RE_2CuO_4 (RE=Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm) was synthesized using high-pressure/oxygen-doped technique. The structures and low temperature magnetic properties were investigated. The XRD patterns indicate that the structures of high oxygen pressure RE_2CuO_4 (only for RE=Sm, Eu) samples are pure T′ phase, but when RE= Gd, Tb, Dy, Ho, Er, Tm, the structures turn to disorder. The magnetic anomalies that occurred at T^30 K are observed in high oxygen pressure RE_2CuO_4. It is found that the transition temperatures of weak ferromagnetic anomalies are nearly independent of the rare-earth components. Thus, the O-doping plays an important role in anomalous magnetic properties of RE_2CuO_(4+δ). The magnetic anomalies in RE_2CuO_4 are considered to be due to ferromagnetic clusters formed in the Cu-O plane after the oxygen doping.

Advanced high-pressure transport measurement system integrated with low temperature and magnetic field

We briefly introduce a new high-pressure transport measurement system integrated with low temperature and magnetic field that is being established as one of the user experimental stations of the Synergetic Extreme Condition User Facilities in the Huairou District of Beijing, China. To demonstrate the capabilities of the system for condensed matter research, the emergence of some pressure-induced phenomena and physics related to superconductivity found previously is also introduced, and then a perspective for such an advanced high-pressure system is presented.

Pressure-Induced Metallization and Electrical Phase Diagram for Polycrystalline CaB_6 under High Pressure and Low Temperature

The electrical properties of polycrystaltine CaB6 are revealed by in-situ resistance measurements under high pressure and low temperature. Due to the existence of grain boundaries, polycrystalline CaB6 behaves with semiconducting transport properties, which is different from the semimetallic CaB6 single crystals. The temperaturedependent resistance measurement results show that before the structural phase transition at 12.3 GPa the high pressure first induces the metallization at 6.5 GPa for CAB6. Moreover, the phase diagram for CaB6 is drawn based on the investigated electric conducting properties and at least three different conducting phases are found even at moderate high pressure and low temperature, indicating that the electric nature of CaB6 is very sensitive to the environment.

Practice and Cognition of Midway VSP in High Temperature and High Pressure Field of South China Sea

Ying-Qiong Basin is a typical high-temperature and overpressure basin, which is the main battlefield of oil and gas exploration in South China Sea and has made great breakthroughs in recent years. During drilling process in high pressure, the relationship between the deep and the pressure is directly related to the drilling safety and costs. In order to improve prediction accuracy, the VSP operation is carried out through the midway, and three points have been obtained: 1) The VSP has a higher accuracy of the interface depth in certain depth range of the drill bit. 2) When the low-frequency trend prediction is accurate before the drill bit, interval velocity of the VSP inversion is consistent with the formation velocity. 3) The VSP pressure forecast is based on the inversion layer velocity and under-compaction pressure. If the velocity prediction is not accurate, the pressure forecast must be erroneous. If the pressure has other sources, the formation pressure is not accurate even if the inversion velocity is accurate. The application scope and exploration effect of midway VSP operation are summarized and applied to Ledong 10-1 block in Yinggehai basin, which realize the breakthrough in the field of high temperature overpressure and provide the basis for other similar exploration areas to do VSP operation.

Interannual and Interdecadal Variability of East Asian Acas and Their Impact on Temperature of China in Winter Season for the Last Century

The interannual and interdecadal varinbility of the Siberian High (SH) and the Aleutian Low (AL) from aspects of strength and location for the past one hundred years as well as their possible relations with temperature changes over China's Mainland are investigated. The data sets used are the historical sea level pressure for 1871-1995 and surface air temperature (SAT) over China in the last 100 years. The results show that the SAT in different regions over China, central strength of the SH and the AL, the south-reaching latitude of the 1030 hPa contour of the SH and the pressure gradient between the SH and the AL experienced two obvious changes during this period. One occurred in the 1920s, with a more prominent one in the 1980s. These variations are closely linked with the change of winter temperature over China in the interdecadal timescale. In the last 50 years, there is a remarkable interannual correlation between the strength of Active Centers of Atmosphere (Acas) and the winter temperature of northern and eastern regions in China. The abrupt change of Acas in the 1980s is consistent with the rising of the SAT in China. Since the late 1980s, the atmospheric circulation is experiencing a remarkable modulation, which may cause the interdecadal transition of warming trend.

Resistivity response to the porosity and permeability of low rank coal

Laojunmiao coal samples from the eastern Junggar basin were studied to understand the relationship between coal resistivity and the physical parameters of coal reservoirs under high temperatures and pressures.Specifically,we analysed the relationship of coal resistivity to porosity and permeability via heating and pressurization experiments.The results indicated that coal resistivity decreases exponentially with increasing pressure.Increasing the temperature decreases the resistivity.The sensitivity of coal resistivity to the confining pressure is worse when the temperature is higher.The resistivity of dry coal samples was linearly related to φ~m.Increasing the temperature decreased the cementation exponent(m).Increasing the confining pressure exponentially decreases the porosity.Decreasing the pressure increases the resistivity and porosity for a constant temperature.Increasing the temperature yields a quadratic relationship between the resistivity and permeability for a constant confining pressure.Based on the Archie formula,we obtained the coupling relationship between coal resistivity and permeability for Laojunmiao coal samples at different temperatures and confining pressures.

基于压力衰减法的低渗透储层高温敏感性评价实验

低渗透油气藏在钻完井过程中易受到损害且难以解除,而利用传统的稳态驱替法评价低渗透储层损害存在适用性差及实验效率低等技术局限。为此,基于压力脉冲衰减法基本原理,分析了上游压力衰减规律及其与岩心渗透率的关系,以岩心损害前后压力脉冲衰减时间为评价指标,建立了适用于低渗透储层损害评价的实验设备与方法,并利用渤海湾盆地渤中凹陷深部低渗透砂岩岩心,开展了室温和150℃高温条件下的敏感性实验。研究结果表明:(1)当实验条件一定时,压力衰减时间仅与岩心的渗透率有关,压力脉冲衰减法可在无需计算渗透率的情况下对低渗透岩心的损害程度进行评价;(2)实验设备组成简单且操作便捷,避免了复杂的渗透率计算及其带来的误差,实验所需时间远低于常规的稳态法且可重复性良好,在低渗透气藏、特低渗透及超低渗透油藏具有很好的适用性;(3)高温环境明显加剧了储层的敏感性损害,深部高温储层损害特征及技术对策研究需要充分考虑高温的影响。结论认为,该认识解决了传统低渗透储层敏感性评价方法适用性差的难题,为高温低渗透储层保护技术对策研究提供了实验方法支撑和理论依据。

高低温对碳纤维/环氧树脂复合材料高压气瓶的性能影响

为了获得T1000碳纤维/环氧树脂复合材料高压气瓶环境适应能力,有效地掌握气瓶高低温适应性固有规律,以容积50 L、工作压力30 MPa的复合材料气瓶(钛为内衬、碳纤维/环氧树脂为复合层)为研究对象,首先介绍了高低温循环下带压气瓶(在-40~80℃范围内成功通过热真空、热循环验证,具备高压承载能力)的热真空、热循环试验数据,然后采用与气瓶相同复合材料的拉伸试样(缠绕角分别为0°和90°),通过高低温极限摸底试验获得了复合材料经历不同梯度高低温后的拉伸性能数据,通过数据比对分析获得了高低温影响拉伸强度衰减的规律。同时,提出了一种高低温极限摸底试验的可靠性评估方法。结果表明,在-50~100℃范围内,试样拉伸强度及断裂伸长率变化较小;当温度高于100℃时,纤维和树脂的性能发生衰减,导致拉伸强度明显降低;当温度低于-50℃时,树脂的性能发生衰减,纤维受到的影响较小。试样高低温极限摸底试验的可靠度大于0.999,表明采用拉伸试样高低温拉伸强度数据的替代方式具有较高的等效性。

煤的温压吸附试验方法与等温吸附试验方法比较研究

为了研究煤的温压吸附试验方法在煤层气吸附方面的可行性,本文对煤的温压吸附试验方法与煤的高压等温吸附试验方法进行了比较研究。分别取12个、10个、8个、和6个温压吸附试验点作为四组不同温度和相应不同压力作为温压吸附试验点,记为V_(实测)。使用温度-压力-吸附方程(Temperature-Pressure-AbsobingEquation(TPAE)),将方程转化为二元一次方程后进行线性回归计算其余三个参数,将所得的四个参数记为V_(计算)。通过计算_(实测)与V_(计算)之间的平均相对误差和标准偏差以衡量温压吸附试验方法的可行性。

黏温黏压下径向柱塞泵滑靴副温度分布与泄漏量分析

针对高压大排量径向柱塞泵滑靴副摩擦失效和泄漏问题,以XDP1000型径向柱塞泵为例,对滑靴副温度分布与泄漏量进行了流场仿真和数值计算。首先,根据滑靴柱塞组件运动学特性分析,求解了滑靴偏转角变化规律,并通过建立滑靴副不同通道流量计算公式的方式,建立了滑靴副静压支承特性方程;然后,建立了滑靴副泄漏功率损失和摩擦功率损失模型,求解了滑靴副最佳油膜厚度,并分析了最佳油膜厚度的变化规律;最后,在考虑了油液黏温黏压特性的基础上,通过流场数值计算的方式,研究了滑靴副温度分布与泄漏量随径向柱塞泵工况参数的变化规律。研究结果表明:额定工况下,滑靴副最佳油膜厚度值约为14μm,滑靴副最佳油膜厚度值随着转子转角的增大而增大,随着工作压力和温度的增大而减小;滑靴运动方向侧油膜温度较另一侧高13 K,滑靴副温度值基本不受工作压力的影响,而随着转速的增大而升高;滑靴副阻尼孔泄漏量较滑靴边界泄漏量大0.02 kg/s,而且泄漏量随着压力、转速和油液温度的增大而增大。该研究结论可为高压大排量径向柱塞泵滑靴副设计及优化提供参考。

一种耐酸耐碱高强树脂的合成及性能

小套管二次固井是一种新型的固井工艺,针对目前由于水泥自身脆性大易气窜和水窜且为碱性固化体、易受压产生裂缝、易受酸性介质破坏的问题,以D-33二元醇和顺丁烯二酸为原料,苯乙烯作为活性稀释剂合成了一种不饱和型聚酯树脂。在树脂体系中引入填料,提高产品韧性及抗压强度。采用傅里叶变换红外光谱仪对树脂进行表征;通过万能试验机对树脂体系进行性能评价。结果表明,目标产物包含羰基、碳碳双键和苯环对位取代结构的特征峰,固化体系为过氧化二苯甲酰/N,N-二甲基苯胺,其在50℃、60℃和70℃条件下的添加量分别为0.2%/0.02%、0.1%/0.02%、0.1%/0.01%,万能试验机测试结果显示,在50℃、60℃和70℃下养护24h后的抗压强度分别约为50MPa、70MPa、90MPa。实验获得了一种聚合时间可调、黏度小、抗压强度高且耐酸耐碱的固井材料,有望在水平井重复压裂改造中大规模使用。

低压静电场协同低温高湿解冻对牛肉嫩度和持水性的影响

为探究低压静电场协同低温高湿解冻对牛肉嫩度和持水性的影响,本研究以牛背最长肌为试验材料,分析了低压静电场解冻(电压2500 V,温度4℃,相对湿度50%)、低温高湿解冻(温度4℃,相对湿度98%)、低压静电场协同低温高湿解冻(电压2500 V,温度4℃,相对湿度98%)与低温解冻(温度4℃,相对湿度50%)四种解冻方式对冷冻牛肉剪切力、质构、水分分布、水分含量、持水性、感官评价的影响。结果表明:低压静电场协同低温高湿解冻的解冻时间最短(804 min),其中解冻损失(2.06%)、蒸煮损失(26.09%)与离心损失(15.00%)显著低于其余三种解冻方式(P<0.05),垂直肌纤维剪切力值(95.46 N)和平行肌纤维剪切力值(41.69 N)最低,自由水含量最低,水分迁移较少,水分含量(68.31%)最高,嫩度品质最优,该解冻方式样品的组织状态、气味、弹性及色泽均最优(总体可接受度最高);综上,低压静电场协同低温高湿解冻加快了牛肉解冻速率、减少了汁液流失,改善了牛肉持水性和嫩度,品质最佳。本研究结果将为低压静电场协同低温高湿解冻技术在冷冻牛肉解冻的产业应用提供理论依据。

龙凤山气田易漏井不承压泡沫水泥浆固井技术

中国石化龙凤山地区面临井温高、地层承压能力低、周期长、承压堵漏成本高等系列固井技术难题,导致固井周期长、费用高且固井质量无法保证等。为解决上述问题,在分析工区现有固井工艺的基础上,提出了不承压泡沫水泥浆固井设计思路,形成了龙凤山地区不承压泡沫水泥浆固井工艺,建立了泡沫水泥浆井内密度及恒密度注气固井计算方法与固井工艺;优选了发泡剂、降失水剂和早强剂等泡沫水泥浆关键外加剂,开发了新型低密度泡沫水泥浆体系,耐温性可达到120℃以上,泡沫半衰期大于420 s、水泥浆30 min失水32 mL、48 h强度13.3 MPa,各项性能均可满足中石化龙凤山气田高温、深井固井要求;形成了适合于龙凤山气田泡沫水泥浆固井技术。现场11口井应用表明,该项技术能够有效提高固井质量,避免了固井前承压、分级或尾管固井作业,平均节约承压堵漏周期7 d以上,经济效益显著。龙凤山气田泡沫水泥浆固井技术对解决中国石化其他工区深井、高温井固井漏失、承压堵漏等难题具有重要借鉴意义和可持续性推广价值。

致密储层岩石超低渗测试系统研发与应用进展

面向深部非常规能源开发领域,自主研制了一套适应于储层特性和深埋环境的超低渗测试系统,旨在解决高地温、高地压、高孔压条件下致密岩石超低渗透率精准测定的难题。该系统由渗流管路和高温高压多通道压力室两部分重要组件构成,经过创新设计和系统优化,能稳定且可靠地模拟150℃高温、150 MPa围压和100 MPa孔压的深部储层环境,并能实现从亚纳达西至毫达西量级岩石样品渗透率的脉冲衰减法测量。基于该系统,开展了花岗岩和页岩在不同加卸载循环、有效应力、孔隙压力和温度条件下的渗透率测试。测试结果表明,加卸载循环次数增加有助于减少取样、制样过程中次生变形或次生微裂隙对测试结果的干扰;孔隙压力的提升抑制了气体滑脱效应,测得的表观渗透率更接近固有渗透率;相同有效应力条件下,页岩单一裂隙渗透率比基质渗透率至少高3个数量级;所建立的裂隙渗透率物理模型精准拟合了单一裂隙渗透率的测试结果,适用于刻画有效应力、孔隙压力和裂隙压缩变形共同影响下的裂隙页岩渗透率变化规律;固定有效应力和孔隙压力条件时,页岩渗透率随温度升高而降低。综上所述,所研发的超低渗测试系统可为致密储层渗透率的评价提供技术支撑,相关测试结果有助于加深对深部储层环境中流体运移机制的理解。

高海拔下内燃机车车顶热流输运特性研究

内燃机车车顶排放的高温浮射流会对列车外流场分布和下游设备的散热性能产生影响,研究高温浮射流对车体周围气动特性的影响有助于评估下游设备的散热环境状况。采用三维、非定常、可压缩雷诺时均Navier-Stokes方法的Realizable k-ε两方程湍流模型,对5节编组高速列车进行数值仿真模拟计算,并与实车试验结果进行对比验证。此外,还分析了不同海拔高度、列车运行速度下的高温浮射流扩散效应。结果表明:随着海拔高度升高,大气密度减小,柴油机排放的高温气体所受的惯性力加强,气流向上运动趋势增加,列车表面最高温度降低。当运行环境的海拔高度由3000 m上升至5000 m时,内燃机车车顶最高温度由117℃下降到86℃。而列车运行速度加快致使柴油机释放的高温气流更贴近列车表面,导致车顶表面最高温度上升。当列车以80 km/h运行在3000 m海拔高度时,列车车顶最高温度为81℃,列车运行速度提高到160 km/h时,最高温度为143℃。研究阐明了高海拔、低气压、低密度的环境中,内燃动力车驱动列车以不同运行速度在明线运行时,柴油机出风口产生的高温气流对列车外流场气动特性的影响机制。

低压喷雾冷却高温高速排气技术研究

为研究在高温高速排气中使用低压喷雾冷却的传热传质特征,本文采用理论推导的方法建立了适用于高速排气中喷雾冷却快速计算模型,包括基于热力学理论的喷水量零维计算模型、基于喷雾学的液滴粒径和液滴受力零维计算模型、基于拉格朗日法的单液滴蒸发运动轨迹二维模型。基于这些模型,先分析采用柴油机海水泵低压供水喷雾的粒径,阐释高速排气弥补海水泵供水压力低的不足,减小液滴粒径的原理;然后分析排气管道内液滴的沉降风险,从液滴受力的角度说明在竖直管道内进行低压喷雾冷却的优越性;最后研究并比价了水平管道和竖直管道内低压喷雾单个液滴的运动蒸发轨迹,直观展示出液滴蒸发与运动关系的生命历程。结果表明,在竖直管道内采用低压逆流喷雾是效果最佳的喷雾冷却方式。

莺歌海盆地东方区高温高压储层物性特征评价研究

通过采用薄片鉴定、扫描电镜分析及图像分析等技术系统地认识高温高压条件下岩石学特征、成岩作用及低渗储层成因机制。结果表明:黄流组一段储层物性受控于沉积微相,临滨砂坝物性最好,平均为17.1%,泥质含量较低;临滨滩砂物性次之,分布相对集中,平均值为12.6%,滨外砂坝最差,平均值为13.1%。该项研究成果对高温高压储层物性研究具有重要指导意义。

高温共烧陶瓷大深径比通孔填充工艺改良

通孔填充是高温共烧陶瓷(HTCC)制作流程中的关键工艺之一,直接影响着元件内部不同层之间电气连接的可靠性。此工艺主要是对冲孔后的陶瓷片进行通孔金属化,即将具有导通作用的金属浆料填充进通孔内。随着通孔深径比增大,常规通孔填充技术无法保证通孔填充质量,通孔填充工艺急需改良。影响通孔填充质量的因素较多,分析了浆料黏度、填孔压力、刮刀速度、刮刀硬度对大深径比通孔填充质量的影响。研究结果表明调整填孔压力、调整浆料黏度及降低刮刀速度均能改善通孔填充效果;刮刀硬度对填孔效果影响较大,当刮刀硬度降低至邵氏A60°~A70°时可保证大深径比通孔填充质量。这一研究结果可为高温共烧陶瓷填孔工艺中通孔填充质量的改善提供参考。