基于流固耦合传热模型的井下注天然气流量测量仿真研究

注气是一种常见的提高油田采收率、延长油田生产寿命的措施,将气体(天然气、二氧化碳、空气等)通过注入井注入到油层中,以保持或恢复油层压力,使油藏有很强的驱动力,进而提高油藏的开采速度和采收率。综合考虑气源稳定性、成本、运输、腐蚀性及混相压力等因素,天然气或伴生气被认为是最有前景的选择。井下气体流量测量是实现精确定量分层注气的重要技术手段,然而由于天然气组分不固定以及井下高温高压的复杂工况,其流量的精确测量及现场标定面临很大挑战。基于流固耦合传热模型对热式流量计在不同工况下的天然气流量测量进行仿真研究,模拟高温高压下的实验环境,建立气体质量流量与温差之间的输入输出关系,为后续现场实验和测量提供有效指导。

高酸性天然气流量测量的修正方法

由于高酸性天然气中含有较高浓度的H2S和CO2气体,对天然气的临界温度和临界压力有较大的影响,导致天然气的压缩因子增大.因此,当采用常规天然气流量测量仪表用于高酸性天然气的流量测量时,需要针对其测量结果进行必要的修正.通过查阅大量的文献资料,对各种天然气压缩因子计算方法进行分析、比较,提出采用Wichest-Aziz校正方法与Bumett关系式相结合的方法计算高酸性天然气的压缩因子,在其适用条件范围内（温度为-12.2～93.3℃,压力为0～13.789 6 MPa,酸性组分H2S＋CO2的摩尔分数不大于80％）,计算得到的天然气压缩因子准确度较高,适于工程应用,也便于实现电算化,利用该方法计算的酸性天然气压缩因子与直接采用Bumett关系式计算的天然气压缩因子（替代常规天然气流量测量仪表内部计算的天然气压缩因子）相比,即可有效地求得天然气流量测量仪表的修正系数,从而提高了酸性天然气流量测量的准确度.

天然气流量测量中高精度温压补偿方法的研究

对天然气在常温常压下的温度、压力、压缩系数之间的关系进行了分析 ,得到天然气在标准状况附近的温度、压力与气体压缩系数的精确的关系 ,提出了一种对天然气流量测量的高精度的温压补偿方法。

利用在线色谱仪测量天然气能量

本文介绍了利用在线色谱仪测量天然气热能量的原理和仪器构成。并对色谱仪分析C6以上元素的注意事项进行了讨论。

浅议测量天然气的流量计选择

实际上,天然气计量测量的是天然气的流量,检测于天然气流动的过程当中。测量的准确度在很大程度上取决于流量计的选择、整套测量系统的合理设计、安装和操作等。本文将针对测量天然气流量计的几种常见类型进行分析,并提出在选择上应注意的问题,以供广大同行参考。

对真空蒸馏脱气自动控制系统的研究

开发了一种钻井液真空蒸馏脱气自动控制系统 (简称 AVMS) ,采用该气路流程方式的天然气组分分析仪在钻井现场天然气测量中提高了分析密度 ,文中给出了 AVMS的工作原理。

Analytical solution of coal-bed methane migration with slippage effects in hypotonic reservoir

Using theoretical analysis, the single-phase gas seepage mathematical model influenced by slippage effects was established. The results show that the pressure of producing wells attenuates more violently than the wells without slippage effects. The decay rate of reservoir pressure is more violent as the Klinkenherg factor increases. The gas prediction output gradually increases as the Klinenberg factor increases when considering gas slippage effects. Through specific examples, analyzed the law of stope pore pressure and gas output forecast changing in a hypotonic reservoir with slippage effects. The results have great theoretical significance in the study of the law of coal-bed methane migration in hypotonic reservoirs and for the exploitation of coal-bed methane.

Resistivity in Formation and Decomposition of Natural Gas Hydrate in Porous Medium

A new one-dimensional system for resistivity measurement for natural gas hydrate(NGH)exploitation is designed,which is used to study the formation and decomposition processes of NGH.The experimental results verify the feasibility of the measurement method,especially in monitoring the nucleation and growth of the NGH. Isovolumetric formation experiment of NGH is performed at 2°C and 7.8 MPa.Before the NGH formation,the initial resistivity is measured to be 4-7Ω·m,which declines to the minimum value of 2-3Ω·m when NGH begins to nucleate after the pressure is reduced to 3.3 MPa.As the NGH grows,the resistivity increases to a great extent,and finally it keeps at 11-13Ω·m,indicating the completion of the formation process.The NGH decomposition experiment is then performed.When the outlet pressure decreases,NGH begins to decompose,accordingly,the resistivity declines gradually,and is at 5-9Ω·m when the decomposition process ends,which is slightly higher than the resistivity value before the formation of NGH.The occurrence and distribution uniformity of NGH are determined by the distribution and magnitude of the resistivity measured on an one-dimensional sand-packed model.This study tackles the accurate estimation for the distribution of NGH in porous medium,and provides an experimental basis for further study on NGH exploitation in the future.

Flow characteristics by particle image velocimetry in liquefied natural gas vaporizer model with several baffles

Shell-and-tube vaporizers are the most commonly used and dominated types of vaporizers in liquefied natural gas （LNG） realm. Due to efficient performance, shell-side flow in this type of vaporizers has received considerable attention and has been investigated extensively. However, the detailed flow structure in the shell needs to be determined for reliable and effective design. Therefore, the objective of this study was to clarify the flow structure in shell by particle image velocimetry （PIV）. Experiments were conducted using two types of model; 15% baffle cut having inlet and outlet positions !n the direction of 90° to the cut and 30% baffle cut having inlet and outlet positions in the direction of 180° to the cut. Each test section is 169 mm in inner diameter and 344.6 mm in length. The flow features were characterized in different baffle cuts with regards to the velocity vector field and velocity distribution. The results show that the flow characteristics of 15% baffle cut type vaporizer are comparable to those of 30% baffle cut type vaporizer.

Dynamic effects of high-pressure pulsed water jet in low-permeability coal seams

Mine gas extraction in China is difficult due to the characteristics such as micro-porosity,low-permeability and high adsorption of coal seams.The pulsed mechanismof a high-pressure pulsed water jet was studied through theoretical analysis,experimentand field measurement.The results show that high-pressure pulsed water jet has threedynamic properties.What's more,the three dynamic effects can be found in low-permeabilitycoal seams.A new pulsed water jet with 200-1 000 Hz oscillation frequency andpeak pressure 2.5 times than average pressure was introduced.During bubble collapsing,sound vibration and instantaneous high pressures over 100 MPa enhanced the cuttingability of the high-pressure jet.Through high-pressure pulsed water jet drilling and slotting,the exposure area of coal bodies was greatly enlarged and pressure of the coal seamsrapidly decreased.Therefore,the permeability of coal seams was improved and gas absorptionrate also decreased.Application results show that gas adsorption rate decreasedby 30%-40%and the penetrability coefficient increased 100 times.This proves that high-pressurepulsed water is more efficient than other conventional methods.

Corrosion depth prediction based on non-linearity method

Pipeline of oil and gas have an increased risk because of pipeline punctures and rupture caused by corrosion. Therefore it is very important to have a reliable way for pipeline corrosion prediction. The corrosion depth prediction models that based on the support vector machines and chaos were introduced in this paper. A real example was given in this paper. The predicted results showed that the prediction models have a more higher precision. The two corrosion depth prediction models are reasonable in corrosion research, which can supply a scientific basis for pipeline safety management, service life prediction and repair.

Application of wireline formation tester in Tarim Oilfield

The application of wireline formation tester(WFT)gradually extends in oil-field with the constant improvement of instrument functions.Applications of WFT in oil and gas exploration in Tarim Oilfield,such as formation pressure measurement,are described,and testing efficiency between drill stem testing(DST)and WFT are compared,especially comprised of PVT sampling,hydrocarbon composition estimation,fluid characterization analysis and formation permeability analysis.The test results between WFT and traditional DST show that their functions can be complementary.The influence factors of WFT and the suitable applying conditions for WFT and DST are also discussed.

影响孔板计量装置计量准确性因素研究

天然气计量中,使用最多的是孔板流量计。正常情况下,它的测量准确度能满足国家标准和石油部标准的要求。但在实际工作中,由于节流装置设计、制造、安装和使用不符合标准,参数选择不当,用户负荷变化,人工取值不准等原因,都不同程度地影响着流量测量的准确度。因此,找出影响孔板计量装置计量准确性因素及解决办法是关系到计量准确的重要工作。