SOLUTION NONUNIQUENESS FOR SEPARATED GAS-LIQUID FLOW IN PIPES AND WELLS. II. ANALYSIS

As shown in [10], multiple solutions may occur for upward flow for separated flow in a pipe without wall mass transfer. For the wellbore flow with wall inflow (production well) case, multiple solutions only exist for upward flow for the gas inflow-dominant case, whereas they may exist for upward, horizontal and downward flow for liquid inflow-dominant situations. The opposite is expected for the wall outflow (injection well) case. The transient models have been proposed for separated (stratified and annular-mist) gas-liquid flow in pipes or wells and successfully applied to validate, both physically and numerically, the correct solution of liquid holdup and pressure drop whenever multiple solutions exist for separated flow. Physical considerations and numerical simulation have shown that only the solution with the lowest liquid height (holdup) is physically realistic. The solutions corresponding to the intermediate and the highest liquid holdup may not be able to lead to a stable flow.     

SOLUTION NONUNIQUENESS FOR SEPARATED GAS–LIQUID FLOW IN PIPES AND WELLS. II. ANALYSIS

ABSTRACT

As shown in [10] Ouyang, L.-B. and Aziz, K. 2001. Solution Nonuniqueness for Separated Gas–Liquid Flow in Pipes and Wells – Part 1: Occurrence. Petroleum Science and Technology, in press [Google Scholar], multiple solutions may occur for upward flow for separated flow in a pipe without wall mass transfer. For the wellbore flow with wall inflow (production well) case, multiple solutions only exist for upward flow for the gas inflow-dominant case, whereas they may exist for upward, horizontal and downward flow for liquid inflow-dominant situations. The opposite is expected for the wall outflow (injection well) case. The transient models have been proposed for separated (stratified and annular-mist) gas–liquid flow in pipes or wells and successfully applied to validate, both physically and numerically, the correct solution of liquid holdup and pressure drop whenever multiple solutions exist for separated flow. Physical considerations and numerical simulation have shown that only the solution with the lowest liquid height (holdup) is physically realistic. The solutions corresponding to the intermediate and the highest liquid holdup may not be able to lead to a stable flow.     

水平井筒气水流动规律及影响因素

由于流动方向变化及壁面流体的不断径向入流，水平井筒的气水流动规律与常规直井存在较大差异。在总结前人研究结果的基础上，优选水平井筒气液两相预测模型，并在验证模型可靠的情况下，考虑管壁入流和气液流型变化，改变气量、水量、管径、倾角、轨迹波动、气水入流位置等多个影响因素，对水平段流型、压力分布规律及影响因素进行综合预测分析，为水平气井的生产管理及后期措施优化提供依据。研究结果表明，一般生产条件下水平井筒存在分层流、间歇流和环雾流3种流型，管径和倾角对水平井筒的气、水流型影响最为明显，管壁入流对入流就地井筒流态的影响较小。水平井筒压力损失与气量、水量、轨迹上倾角及轨迹波动起伏程度呈正相关性，而与管径和下倾角呈负相关性。预测范围内，气量、轨迹上倾和管径对水平井筒压力损失的影响最为明显，是水平井筒压降的关键影响因素。随着轨迹上倾角增加，水平井筒压降随气量的变化规律发生明显反转，低气量条件下水平井筒压降随气量的减小而增加，高气量下压降随气量增加而增加。     

水平井筒变质量气液两相流动模型

根据水平井筒和常规水平管道中气液两相流动的相似和差别,可知常规水平管流的流型转换标准用于井筒流动需要进行修正或扩展。根据气液两相界面波的迅速成长机理,考虑了管壁存在入流或出流对于分层流向非分层流流型转变的影响,在Taitel Dukler的研究基础上,得到水平井筒气液两相变质量流动分层流向非分层流流型转变的判别方法。通过对分散泡状流流型中的分散气泡进行受力分析,考虑了管壁入流或出流的影响,得到判别水平井筒气液两相变质量流动分散流向间歇流流型转变的一种新方法。     

水平井筒变质量间歇流压降的理论与试验研究

间歇流是实际水平井筒气液两相流动中非常重要的一种流动形态。由于水平井筒和常规水平管道中气液两相流动的相似和差别,常规管流的压力计算方法对于水平井筒流动来说就需要进行修正和扩展。在常规水平管道间歇流动压降分析的基础上,对气、液两相分别应用质量守恒方程和动量守恒方程,考虑管壁入流或出流对压降的影响,得到一种新的水平井筒间歇流流型压降计算方法。同时,设计并建立了水平井筒流体流动模拟试验装置,在轴向为气液两相流动的前提下分别进行了上管壁单孔眼注入和下管壁单孔眼注入的间歇流动压降试验研究,获得了大量试验数据,与理论计算结果吻合较好,表明该计算方法具有实际应用价值。     

A MECHANISTIC MODEL FOR GAS-LIQUID FLOW IN HORIZONTAL WELLS WITH RADIAL INFLUX OR OUTFLUX

A new mechanistic model for gas-liquid two-phase flow with mass transfer through the pipe wall, which accounts for the effects of wall inflow or outflow on wall friction, acceleration and flow pattern transition, has been developed. Four individual flow patterns, including stratified flow, annular-mist flow, bubble flow and intermittent flow, are considered in the mechanistic model. Models for individual flow patterns have been developed. Transition mechanisms among different flow patterns are discussed and new transition criteria are proposed. Predictions by the new mechanistic model are compared with experimental data obtained on a large industrial facility.     

水平井水平段压降的一个分析模型

根据水平井水平段流体的流动特征，建立了水平井筒压降的一个分析模型，Ｄｉｋｋｋｅｎ的压降模型是本模型的一个特例。在水平井筒内为单相紊流情况下，对其摩擦数进行了讨论；并用实例计算了水平段内单相紊流时的压降。由计算结果可知，在水平水平较长时，不能忽略其中的压力损失。     

水平井筒气液两相变质量流动流型转变的研究

井筒中的流动是管壁存在入流或出流的变质量流动。给定井筒气液流动条件,在应用机械模型预测我们感兴趣的参数之前,我们需要识别井筒中出现的流型。由于水平井筒和常规水平管中气液两相流动的相似和差别,可以预知常规水平管流的流型转换标准对于井筒流动来说就需要进行修正或扩展。根据波的迅速成长机理,在Taitel和Dukler的研究基础上,得到水平井筒分层流向非分层流流型转变的判别方法;通过对分散气泡进行受力分析,得到水平井筒分散泡状流向间歇流流型转变的判别方法;基于Barner和Brauner的研究给出水平井筒环空雾状流向间歇流流型转变的判别方法。从而得到一种判别水平井筒气液两相变质量流动4种基本流型的新方法。     

水平井筒气液两相变质量流动流型转变实验研究

在对水平井筒气、液两相变质量流动的流型转变进行了理论研究,在此基础上,设计并建立了流型转变实验装置,对水平井筒气、液两相变质量流动的流型转变进行了模拟实验研究.在轴向为气、液两相流动的前提下分别进行了上管壁单孔眼注入和下管壁单孔眼注入的流型转变实验研究,获得了大量的实验数据.根据实验数据修正了理论计算模型,修正后的理论模型计算结果和实验数据吻合很好.     

Numerical Study of Stratified Gas-Liquid Flow

In this work the effects of empirical correlations of friction factors (wall and interfacial) on the numerical stability and parameters predictions in stratified gas-liquid pipelines flow, was studied using the two-fluid model, where unequal phase pressure effects were considered. To study the effects of such empirical correlations without taking into account the instabilities due to ill-posed initial-value problems or multiple solutions, the two-fluid model was solved using input data, which satisfies a linear stability criterion where multiple solutions do not occur. In general, we found that the empirical correlations are not important for numerical stability but do, however, affect significantly the parameters predictions.     

Numerical Study of Stratified Gas-Liquid Flow

Abstract

In this work the effects of empirical correlations of friction factors (wall and interfacial) on the numerical stability and parameters predictions in stratified gas-liquid pipelines flow, was studied using the two-fluid model, where unequal phase pressure effects were considered. To study the effects of such empirical correlations without taking into account the instabilities due to ill-posed initial-value problems or multiple solutions, the two-fluid model was solved using input data, which satisfies a linear stability criterion where multiple solutions do not occur. In general, we found that the empirical correlations are not important for numerical stability but do, however, affect significantly the parameters predictions.     

气藏水平井生产系统动态分析模型

对于水平井开发气藏，其生产系统由气藏内渗流和水平井井筒内流动两部分所组成。首先仿造采油指数的定义来定义压力平方形式下的采气指数，分别建立了气藏渗流及水平井筒流动的数学模型，该模型具有压力平方的形式，然后应用体积平衡原理将气藏内流动和井筒内流动联系起来，建立了产量耦合下生产系统分析模型，该模型实际上是水平气井的流入流出动态分析模型，分为层流、光滑管壁紊流、粗糙管壁紊流3种流态，推导出气藏水平井的产量随位置变化的关系式，并分析讨论了管壁相对粗糙度对气藏水平井产能的影响，在考虑水平井水平段内摩阻的情况下，实例分析了气藏水平井的流入流出动态关系。这为钻井工程、描述水平井流入流出动态、评价水平井产能、确定合理生产制度和管壁相对粗糙度对气藏水平井产能的影响提供了可靠的手段和方法。     

水平井变质量管内流动损失的数值研究(二):多支管流动

本文是《水平井变质量管内流动损失的数值研究(一):单支孔流动》[1]的续文,研究多支管水平井筒中流动压降和摩阻。水平井筒中压降及壁面摩擦阻力的沿程变化对水平井的产量有很大影响,因此,掌握水平段的多支孔流动损失和压降规律,对优化水平井长度及开采工艺设计、准确预测水平井产油量至关重要。本文仍采用数值方法,在预测壁面单支管注入对管流压降及壁面摩擦阻力影响的基础上,研究了壁面多支管注入对管流压降及壁面摩擦阻力影响,给出压降系数与壁面注入速度及截面雷诺数的变化规律。     

射孔水平管阻力系数的试验研究

根据现场实际水平井筒的布孔方式,设计并建立了室内水平井筒流动模拟试验装置,对射孔水平管的阻力系数进行了试验研究。射孔水平管当有孔眼流入时阻力系数由三部分组成:水平管固有摩擦系数、由加速损失转换的阻力系数和由水平管主流体流动与孔眼流入混合损失转换的阻力系数。为现场实际水平井流动阻力的计算提供了理论根据。     

肇州油田水平井水平段压降计算及测试

水平井水平段的流动为变径入流量的变质量流动,根据动量守恒方程建立了水平段流动的压力梯度基本方程;通过不同位置的采液指数变化,表征水平井筒中的流动与油藏渗流的耦合,考虑孔眼入流情况下的管壁摩阻系数,建立了一套系统的水平井水平段压降计算模型及方法。水平段压力损失由摩阻压力损失、加速压力损失、混合压力损失以及势能压力损失等四部分组成。对肇州油田州62-平61井水平段压降进行了计算,并在相同生产条件下进行了测试,计算值与实测值误差6％。计算表明,肇州油田9口水平井的水平段总压降大约在0．048～0．26MPa。     

大管径水平管油水两相流动特性试验研究

因井斜变化、流体密度差异等因素致使水平井井中流体流动特性复杂多变,准确进行水平井生产动态监测成为难题。基于水平管油水两相模拟试验,在完全水平流、上坡流和下坡流情况下,对油和水的分布规律、流型分类、速度剖面和滑脱效应等进行了分析,通过剖析3种不同持率测量仪器的响应规律,制作了速度剖面和滑脱速度等试验图版,能很好地用于判断流体流动特性。     

Effect of binary mixtures of surfactants on horizontal gas–liquid flow with low liquid loading

The interaction between anionic and zwitterionic surfactant (sodium dodecyl sulphate/dodecyl betaine) brings about the synergism in the surface tension reduction and the micelle formation. The binary mixtures of surfactants were added to air–water flow with low liquid loading in a horizontal 50.8 mm pipe. Two concentrations with a 6:4 molar ratio of zwitterionic to anionic surfactant were tested to investigate their effect on the frictional pressure drop. Parallel ring conductance technique was used to trace the liquid layer fluctuation near the pipe wall and examine the gas–liquid interfacial behavior. A modified two-fluid model with the consideration of a curved interface is introduced to obtain the closure relationship for scaling the gas–liquid interfacial roughness. It was found that the solution with low concentration did not have drag-reducing effect although the reduced surface tension, while the mixed surfactants solution with the concentration higher than the critical micelle concentration reduced the interfacial roughness, leading to pressure drop reduction at low and medium gas flow rates. At high gas flow rates, the effect of mixed surfactants became worse because of the degraded surface activity and the break-up of the mixed micelle under the high gas shear conditions.     

A homogeneous model for gas–liquid flow in horizontal wells

Radial influx or outflux stands for the major difference between fluid flow in a pipe and fluid flow in a well. A homogeneous model for gas–liquid flow in a horizontal well is presented in this paper. In addition to frictional and gravitational components of total pressure drop, accelerational pressure drops due to fluid expansion and radial influx or outflux are considered. Effect of radial influx or outflux on wall friction is also taken account for. With a segmented approach, the new model and several existing pipe flow models have been applied to predict pressure drop along a wellbore, and predictions are compared with experimental data. It is found that the new homogeneous model outperforms existing models for gas–liquid flow in horizontal wells.     

水平井自适应调流控水装置研制与应用

针对边底水油藏水平井由于跟端趾端效应和水平段地层非均质性造成含水率快速升高的情况,在分析油水物性和调流控水筛管应用工艺的基础上,利用层流与紊流的流动特性,研制了一种能够根据产出流体的情况自动调节附加阻力的"主动式"自适应调流控水装置。流体动力学流场模拟及室内性能试验结果表明,油水流经自适应调流控水装置时,油相的摩阻低、水相的摩阻高,最大水油压降比可达10.0以上,具有自动调节油水附加阻力的功能。自适应调流控水装置在塔河油田底水油藏水平井A井进行了现场试验,与未应用调流控水装置的邻井相比,低含水采油期延长3个月以上。研究与试验表明,自适应调流控水装置可以根据产出流体的情况,自动对产出水进行节流,解决了边底水油藏水平井底水锥进的问题。      

HPAM溶液流变性与减阻关系

通过研究不同浓度、不同分子量的HPAM溶液的流变及摩阻性能,建立了一个聚合物溶液摩阻系数方程。测试了5种不同浓度、4种不同分子量的HPAM溶液的稳态剪切黏度、触变性、流动曲线等流变性能;并分别测试其在管内径为0.77 cm,流量为3～9 L/min的压差数据,计算得摩阻系数数据,分析了聚合物分子量、聚合物浓度等对溶液减阻的影响,建立了聚合物溶液摩阻系数f和广义雷诺数Re及聚合物溶液流型参数n之间的摩阻系数方程。