Investigation of asphaltene deposition under dynamic flow conditions

Asphaltene deposition is one of the most serious problems, which usually occurs in oil wells, petroleum production, oil processing, and transportation facilities. Deposition of heavy organic components, especially asphaltene, can lead to wellbore blockage and impacts well economics due to reduction in oil production. Therefore, it is necessary to pay more attention to finding some solution to overcome this problem. In this study, a pipe-loop apparatus for investigation of oil stability was employed to measure deposition thickness using a thermal method. The effects of many factors such as oil type, oil temperature, oil velocity, inhibitors, and solvents on asphaltene deposition were investigated. The results showed that the deposition increased with the increasing value of the colloidal instability index. Besides, the deposition thickness increased with the decreasing velocity of oil, but did not change with oil temperature. In addition, n-heptane could result in more deposition; however, toluene had no effect on the deposition. Branched dodecyl benzene sulfonic acid (Branched DBSA) and Linear DBSA as inhibitors decreased the rate of asphaltene deposition.     

抽油杆柱动态特性的计算机模拟

在分析有杆抽油系统抽油杆柱井下基本工况、运动和动力特性的基础上 ,根据抽油机光杆运动方程 ,确定了抽油杆柱井下运动的 4个时间区段及边界条件。采用有限元软件MARC按不同时间区段对多级抽油杆柱的运动和动力学特性进行计算机模拟 ,得到计算机模拟的地面示功图和抽油杆柱一个上下冲程循环中各节点的位移与载荷随时间变化的动态特性曲线。分析对比计算机模拟曲线和实测曲线表明 ,采用有限元软件MARC获得的抽油杆柱计算机动态模拟结果与测试结果基本吻合 ,前者可作为后者的度量基准 ,动态模拟曲线还可为游梁式抽油机设计和井下故障诊断提供理论依据     

电加热柔性连续抽油杆动态特性的计算机模拟

根据电加热柔性连续抽油杆的特性、参数及井下基本工况,建立了三级混合抽油杆柱的有限元模型。运用有限元软件对混合杆柱的动态特性进行计算机模拟,得到各关键点位移、速度随时间变化曲线,以及计算机模拟的地面示功图,为抽油机、抽油杆设计和井下故障诊断提供理论依据。与传统电加热空心抽油杆相比,电加热柔性连续抽油杆在降载和节能方面优势显著。     

流动单元四维动态演化仿真模型研究

流动单元是油气储集最小宏观地质单元,应用室内岩心样品不同注入体积倍数驱替实验、不同开发阶段完钻井的测井参数评价及大量生产动态资料,研究分析了不同成因流动单元在水驱开发过程中储层宏观物性参数的演化规律,进而建立各类参数的数学演化模式,找出其相应物性参数的变化因子.并借助工作站三维地质建模软件Earthvision,在原始三维地质属性参数模型研究的基础上,加载物性参数变化因子,并经数据处理和结果提取,形成各类流动单元随开发过程的四维动态系列演化仿真模型,揭示和预测了不同开发阶段流动单元内部油水运动特点及剩余油分布状况.     

含硫天然气相态及渗流

近年来，四川东北部地区发现了大量硫化氢含量很高的天然气藏。天然气中元素硫的含量受地层压力、温度以及天然气组分的控制，在开采过程中，由于近井区域压力低、气体流速高，将使天然气的状态发生变化，析出的固相硫沉积在储集层的孔隙喉道中堵塞天然气渗流通道，井筒中会沉积更多的元素硫，影响气井产能。采用热力学理论解释了硫随温度和压力变化的沉积规律，建立了在达西流和非达西流条件下渗流过程中的硫沉积方程。图1参20     

膨胀管金属流动行为的计算机模拟研究

膨胀套管技术在我国尚处于理论探索阶段。鉴于此 ,用ADINA软件的弹塑性有限元接触问题建立了可膨胀管膨胀过程的力学模型 ,对壁厚 8 94mm的 2 4 4 5mm套管进行膨胀过程的计算机模拟 ,通过分析和比较沿膨胀管径向不同位置处的单元节点组在X轴和Y轴方向的位移量 ,得出了膨胀管在不同摩擦系数和不同内径膨胀幅度时的金属流动规律 ,为膨胀锥体的结构设计和材料选择以及膨胀技术的实际应用提供了理论依据。     

变工况时气液两相机械密封端面动压实验分析

在理论分析变工况时机械密封动环密封圈摩擦力和比压的变化 ,以及端面轴向力平衡变化的基础上 ,采用 1GX70非平衡型机械密封 ,在实验室模拟变工况条件下开展了气液两相机械密封端面动压实验。实验结果表明 ,变工况时处于气液两相的机械密封 ,因端面间液膜闪蒸而导致端面开启 ,动、静环不再平行 ,动环密封圈摩擦力增大 ,动环追随性遭破坏致使密封失效 ;机械密封的动压膜压沿收敛间隙呈正弦分布 ,计算变工况密封开启力时不但要考虑密封端面闪蒸造成沸腾区压力的影响 ,还要考虑动压的影响     

New dynamic permeability upscaling method for flow simulation under depletion drive and no-crossflow conditions

The main purpose of upscaling in reservoir simulation is to capture the dynamic behavior of fine scale models at the coarse scale.Traditional static or dynamic methods use assumptions about the boundary conditions to determine the upscaled properties.In this paper,we show that the upscaled properties are strongly dependent on the flow process observed at the fine scale.We use a simple no-crossflow depletion drive process and demonstrate that an upscaled property is not a constant value.Instead,if the goal is to match the performance of the fine scale model,the upscaled permeability changes with time.We provide an analytical solution to determine the upscaled permeability and present the value of upscaled permeability under limiting conditions.Our equation suggests that it is possible that upscaled value can fall outside the range of fine scale values under certain conditions.We show that for pseudo steady state flow,using common averaging methods like arithmetic or even geometric averaging methods can lead to optimistic results.We also show that the no-crossflow solution is significantly different than crossflow solution at late times.We validate our method by comparing the results of the method with flow simulation results in two and multi-layered models.     

储层动态流动单元研究——以别古庄油田京11断块为例

流动单元是油气储集最小宏观地质单元，它综合反映了储层的岩性、物性及微观孔喉特征。在分析流动单元定义的基础上，针对高含水期油田开发，提出动态流动单元的概念和定量划分方法。以别古庄油田京11断块为例，从取心井入手，通过优选参数，将储层流动单元划分为4种类型，建立了各类流动单元的数学判别函数，对非取心井进行了流动单元划分，并应用序贯指示模拟建立了不同含水期动态的流动单元模型。研究表明，不同含水期储层流动单元类型受储层物性和流体性质的变化所控制，其分布是动态变化的，动态流动单元能够描述不同开发阶段油水运动规律相似的储集带的动态变化，不同开发阶段的剩余油分布与储层动态流动单元关系密切。实践证实了动态流动单元对剩余油预测的准确性，表明应用动态流动单元方法预测高含水期油田剩余油分布和提高采收率更具有实际意义。     

Characterization of a centrifugal pump impeller under two-phase flow conditions

Multiphase pumping is an area of primary interest, particularly for the petroleum industry, where fair amount of gas can be found in oil wells production. This study presents the results of numerical simulations carried out in a centrifugal pump impeller of an Electrical Submersible Pump (N_s = 2063) conveying an air–water mixture. The results include the impeller head and the relative flow angle at the outlet (β₂) as a function of the liquid flow rate, as well as the phases distribution within the impeller. A sensibility analysis with regard to the Gas-Void Fraction (GVF) and the bubble diameter was also included. The deterioration of the head reported by other investigators (in the case of two-phase flow) is reproduced and substantiated by means of the forces acting on bubbles within centrifugal impellers. Finally, comparison with experimental data is excellent, which demonstrate that Computational Fluid Dynamics (CFD) is a useful tool in the analysis of turbomachinery.     

应力敏感效应的气井流量动态特征研究

在油气藏的开发过程中,特别是对于低渗透油气藏及火山岩油气藏的开发,储层岩石应力敏感性会明显影响油气藏的开发效果。文中考虑了表皮系数及孔隙受应力敏感效应影响而发生变形的问题,利用不稳定渗流理论建立了数学模型,并利用Stehfest数值反演法得到了模型实空间的解。根据实空间中无因次产量与无因次时间的变化关系,分析了表皮系数、无因次应力敏感系数、封闭边界以及定压边界对气井流量动态特征的影响。研究结果表明,科学合理地开发具有应力敏感效应的气藏,可保证气井和气藏的正常生产。     

特高含水水驱油藏流场边界动态追踪模型研究

特高含水水驱油藏油水流动差异、剩余油分散富集现象日益严重.为了从宏观尺度制定油藏动态高效开发策略,提出一套基于界面重构思想的流场边界动态追踪模型,预测了二维及三维流场的速度差异界面、饱和度差异界面演化规律,完成了特高含水油藏区块高速、高含水流场边界定量表征的测试,并制定开发对策验证其工程应用的可行性.在经典黑油模型基础...     

动态水力旋流器圆管螺旋流场特性研究

对动态水力旋流器圆管螺旋流场结构及形成原理作了简要描述。在深入研究动态水力旋流器分离机理及分离性能的基础上,运用圆管螺旋流动方程式进行了动态水力旋流器内部螺旋流动分布理论研究,得到旋流器内部流场按强制涡、自由涡、组合涡及螺旋涡的分布特性。同时利用直圆管柱模型,模拟计算出了圆管螺旋流的理论分布结果。研究和掌握动态水力旋流器内部流体螺旋流的运动及分布规律,为今后深入进行其分离机理、流场测试及分离性能研究打下了一定的基础。     

Computer program for modelling dynamic processes in pipe fittings controlled by the energy of the flowing medium

Translated from Khimicheskoe i Neftyanoe Mashinostroenie, No. 6, pp. 16–20, June, 1991.     

The effect of dynamic cooling on the flow properties of PPD-treated crude oil

Abstract

By means of DSC, test of flow parameters, and microscopic observation, this paper studied the relation between the influence on the low temperature flow properties and that on the waxy crystal of the PPD-treated crude oil due to different final temperature of dynamic cooling. It has been experimental confirmed that the influence caused by the final temperature of dynamic cooling on low temperature flow properties and waxy crystal vary from the different final temperature of dynamic cooling. With this temperature increases, the depressive effects first get worse, then improved and finally kept nearly unchanged at higher temperature.     

天然气高速非达西渗流动态产能计算

真实气体的地下渗流是个不稳定的非线性渗流过程,气井产能受流动规律的影响,并随地层压力及PVT参数的变化而变化.综合考虑天然气高速非达西渗流特征和PVT参数动态特征,建立了外边界封闭气藏中平面径向不稳定渗流数学模型.计算结果表明,考虑高速非达西流和气体PVT参数变化的产能高于达西线性流和PVT参数不变时的产能;计算得到了不同地层压力下不同投产时间的动态IPR曲线,避免了静态IPR曲线中许多不合理的假设,更加符合生产实际.     

旋转控制头侧向力研究

在钻井过程中,方钻杆的侧向力作用常常导致旋转控制头损坏,造成事故。通过将井口至大钩的方钻杆简化为连续梁,将旋转控制头上下胶心和驱动器对方钻杆的约束简化为中间弹性支座,建立了相应的钻柱横振动力学模型。通过对模型的求解,找到了一种计算方钻杆转动对旋转控制头产生侧向力的合理方法,为分析计算不同钻井条件下旋转控制头的受力情况提供了理论依据。     

钻井液固相控制叠层筛网动态特征研究

叠层粘接成形筛网具有优良性,已广泛应用于钻井液固控领域,现文介绍了用机械工程软件（Ｐro/E)对叠层筛网（平面形、波浪形等）的动态特征、仿真、筛网失效分析的研究结果。为叠层筛网的合理使用、性能改进、不断提高对钻井液的筛分效率提供重要的参考依据。     

Low-temperature separation of gas: Simulation of dynamic conditions

The aim of the present paper is to increase the efficiency of low-temperature gas separation plant with use of simulation dynamic model. The paper analyzes the main processes occurring at the installation and performs the results of model verification. In addition, the technological scheme of natural low-temperature gas separation and operating parameters of one of the existing installations were considered. A non-stationary mathematical model of the chemical-technological system of low-temperature gas separation was developed. Due to the unsteady mathematical model, it became possible to estimate the time spent on the transient phenomena, as well as to choose the rate of low-temperature separation control parameters change, depending on the technological mode. Eventually, the calculations show how it is possible to avoid the instability of plant operation upset conditions at the workplace. The field of the developed model application is oil and gas industry and also higher education institutions. This software can be used to test the stability of both existing and projected low-temperature gas separation plants.