泡沫油模型研究现状

引入泡沫油的概念是为了描述原油流动过程中伴随有分散气泡的现象。泡沫油现象被认为是加拿大和委内瑞拉稠油油田出现反常高产和超出预期较高采收率的主要机理。在充分调研泡沫油模型文献的基础上,对各种概念模型的特点进行了比较和总结。加拿大的一些稠油油藏在产出泡沫油的同时伴随有出砂现象,这表明地质力学作用和流体特殊性质2种因素并没有相互排斥,甚至存在两者的耦合作用。泡沫油的形成机理目前依然存在争论,如对于泡沫油的黏度目前尚未形成统一的认识,泡沫油形成过程的影响因素之间是否存在耦合等,要解决这些问题,未来应在泡沫油溶解气驱微观可视化模型和非常规PVT测试的基础上进一步探究其形成机理。     

稠油冷采泡沫油稳定性影响因素微观实验

在加拿大、委内瑞拉以及中国的一些稠油油藏溶解气驱过程中,表现出了异常的开发动态:低的生产气油比、高的采油速度和高于预期的一次采收率.普遍认为泡沫油是产生这种异常动态的重要机理之一.为此,通过玻璃微模型实验观察了泡沫油形成过程中微气泡的产生、运移、合并、破裂以及最终产生连续气相的全过程;同时研究了影响泡沫油稳定性的几个影响因素,即压力衰竭速率、温度、原油黏度、溶解气油比等.实验结果表明,压力衰竭速率及原油黏度是泡沫油形成和稳定性的主要影响因素.该研究有利于进一步认清泡沫油现象的微观机理.     

稠油重力驱渗流速度影响因素分析

以稠油重力与压力复合开发机理为基础,采用计算流体动力学软件ANYSY CFX计算分析原油黏度,油层厚度、含油饱和度及压力梯度对油（水）渗流速度影响。研究表明：稠油重力驱过程中,原油黏度不同影响油水渗流速度的因素不同。存在临界原油黏度,当小于此临界黏度时主要受油层厚度影响,当大于此临界黏度时主要受含油饱和度影响。在驱泄复合过程中,油（水）渗流速度主要受压力梯度影响。取得研究成果为稠油重力驱渗流研究提供借鉴。     

出砂冷采稠油油藏泡沫油研究进展

稠油广泛蕴藏于加拿大、委内瑞拉、中国等国家,出砂冷采作为一种有效的稠油冷采技术,主要通过形成泡沫油而获得高产油流,因此,加强泡沫油的相关研究对该类油藏的开发至关重要。调研了中外关于出砂冷采稠油油藏泡沫油的研究现状及最新进展,从分析泡沫油油藏非常规特征入手,系统介绍了泡沫油的定义及性质,详细说明了泡沫油非常规高压物性及压力衰竭实验方法及研究内容,总结了泡沫油孔隙网络模拟及宏观数值模拟方面的研究进展。加强泡沫油流的理论研究,明确岩石流体特征、操作条件等对泡沫油流的影响,探索泡沫油油藏开发后期有效的接替技术是今后的研究重点和方向。     

泡沫油国内外研究进展

在加拿大、委内瑞拉以及中国的一些稠油油藏溶解气驱过程中,表现出了异常的开发动态:低的生产气油比、高的采油速度和高于预期的一次采收率。"泡沫油"被认为是这种异常生产动态的原因之一,油相连续的含有大量气泡的原油称为泡沫油。在参考大量相关文献的基础上,总结了国内外在泡沫油定义、性质、形成过程、影响因素以及机理研究等方面的进展,其中重点研究了过饱和度、临界气相饱和度、原油黏度、压力衰竭速度和溶解气油比对泡沫油特性的影响,进一步分析了一些解释泡沫油机理的数学模型,指出了各自的优缺点以及存在的问题,并对稠油冷采泡沫油今后的研究方向提出了一些建议。     

Orinoco油藏泡沫油性能评价研究

Orinoco稠油油藏采用的是压力自然衰竭的开发方式,在开发过程中具有产油量高、产气量低和降压速度慢等特征,在开采过程中会出现"泡沫油"现象。为了研究泡沫油在地层中的稳定性及流变性,利用自主研发的高温高压泡沫油配样器配制泡沫油,分析了黏度、温度、矿化度、溶解气油比等对泡沫油稳定性的影响,并通过流变仪和岩心流动装置分别测量了泡沫油的流变性。实验结果表明:随着脱气原油黏度增大,泡沫油的半衰期变长,稳定性越好;温度越高,稳定性越差;溶解气油比越高,泡沫油稳定性增强;矿化度对稳定性影响并不明显;Orinoco泡沫油具有剪切变稀的性质和轻微触变性;在多孔介质中,随着注入压力的增大,泡沫油黏度先降低后增大,相同压力梯度下,泡沫油的流度明显高于脱气原油流度。该研究提升了人们对泡沫油性能的认识,有利于进一步完善泡沫油性能研究。     

特稠油油田井间干扰评价及应用

在气藏、煤层气藏、稀油油藏的开发中普遍存在井间干扰现象。目前,我国海上开发黏度最大的某稠油油田的生产实践发现,衰竭开采的特稠油油藏也同样存在井间干扰现象。文中从油田实际干扰现象出发,建立数模模型进行定量评价。研究结果发现:原油黏度越大,其渗流速率越慢,泄油半径越小;原油黏度越大,井底压降漏斗越深。这是由于稠油黏滞阻力大,流动所要消耗的压降能耗远远大于普通稠油。随生产时间的增加,其压降漏斗越来越深,泄油半径越来越大。当井距大于280 m时,或定向井之间,井间干扰不明显。井间干扰主要发生在高产井之间及后投产井与先投产井之间。井间干扰对先投产井造成的不利影响,可以通过调整井距减弱,该研究成果对于稠油油田合理井距的确定有指导意义。     

稠油油藏水平井产能预测新模型

不同黏度下稠油室内实验研究结果,证明了稠油流动中存在启动压力梯度,启动压力梯度随原油黏度的增大而增大。考虑水平井三维空间渗流特征和启动压力梯度,应用速度势理论建立了稠油油藏水平井产能预测新的数学模型。应用新模型,对海上稠油油藏水平井产能进行了预测,分析了启动压力梯度对稠油油藏水平井产量和动用范围的影响:启动压力越大,水平井产能越低;启动压力梯度增大了渗流的阻力,减小了水平井的动用范围。     

超深层稠油降黏泡沫体系微观作用机理及其矿场应用

超深层特稠油油藏热采效益差、水驱效率低，需要依靠技术创新才能实现经济高效开发。通过开展降黏型泡沫体系开发机理物理模拟与分子模拟研究，并在鲁克沁油田超深层特稠油油藏进行了矿场实践。研究结果表明，优选的苯磺酸盐型阴离子活性剂HY-3J在高矿化度地层水环境下，既能形成较为稳定的泡沫体系，又能形成水包油乳状液降低稠油黏度。泡沫微观渗流实验结果表明，泡沫可以利用其液膜的黏弹性对稠油产生微观作用力，该作用力可以高效乳化降黏稠油。岩心驱替实验表明，超深层稠油水驱采出程度仅为12.7%。降黏泡沫体系可以显著降低含水率，提高产油速度，降黏泡沫驱提高采出程度17.4%。分子模拟结果表明，苯磺酸盐阴离子活性剂的苯环结构可以与沥青质上的芳香环形成π—π相互作用，这提高了活性剂与沥青质的范德华相互作用能，从而有利于解聚稠油沥青质形成的网状结构，降低稠油黏度。降黏泡沫体系在鲁克沁油田实施了8个井次降黏泡沫体系吞吐，均取得了较好的降水增油效果，这说明降黏泡沫体系可以有效改善超深层特稠油开发效果。     

稠油活化剂降黏机理及驱油效果研究

稠油降黏冷采是海上油田开发的主要方式,为深入认识稠油活化剂的降黏机理及其在原油黏度为150～1 000 mPa·s的稠油油藏中的应用效果,通过室内物理模拟实验和耗散粒子动力学模拟技术,研究了稠油活化剂对稠油的降黏机理及驱油效果。结果表明,稠油活化剂可提高水相黏度、降低油水界面张力,能有效降低常规可流动稠油的黏度。分子尺度上的研究结果显示,稠油活化剂分子对沥青质聚集体有明显的阻聚-分散效果,其活性基团能增大沥青质芳香盘的层间距和链间距,减小沥青质聚集体堆积高度和堆积层数,削弱沥青质间的相互作用,破坏稠油重质组分聚集结构,分散稠油,从而增强原油流动能力。稠油活化剂的多种机理协同作用使其在室内岩心驱替实验和矿场应用中,均可起到良好的降水增油效果。该研究从分子层面明确了活化剂降低稠油黏度机理,为稠油活化剂现场应用提供理论指导。     

Experimental investigation on rheological property of foamy oil in Venezuela

Some heavy oil reservoirs present foamy oil flow behavior under primary production, and the foamy oil viscosity and rheological property are important factors that influence the efficiency of the process. The variation of the foamy oil viscosity during the depletion process is complicated due to the generation and migration of dispersed gas bubbles within the oil phase, and still remains as a controversial topic.

?This study aims to investigate this issue by measuring the foamy oil viscosity at different pressure, temperature and flow rate with a capillary viscometer system equipped with a specially designed foamy oil generator to guarantee the generation and stable flow of gas-in-oil dispersions. Meanwhile, the dead oil and live oil viscosities were also measured for comparison.

?Based on the results from all the tests the following conclusions can be drawn. Below the bubble point pressure, the dispersed gas-bubble volume fraction and foamy oil viscosity increase with pressure decline; the viscosity of foamy oil is higher than that of live oil, and the gap between them widens with pressure decline. Moreover, foamy oil behaves as shear-thinning power-law fluid, and the shear-thinning effect becomes stronger with the decrease of pressure. The foamy oil rheology is also affected by temperature, and the shear-thinning effect becomes milder with the increase of temperature. Based on the experimental data, a formula was established for estimating foamy oil apparent viscosity within porous media, which took flow rate, shear-thinning flow parameters, permeability, porosity and other factors into consideration.     

稠油溶解气驱泡沫油特征实验研究

压力衰竭速度是影响稠油溶解气驱泡沫油生产的一个关键因素。为定量描述压力衰竭速度对泡沫油现象的影响,实验选取了4组不同压力衰竭速度进行实验。研究不同压力衰竭速度下稠油衰竭开采中的采收率、产油量、生产气油比以及实验压力的变化。通过实验发现稠油溶解气驱过程中出现明显的泡沫油阶段,且压力衰竭速度越大,泡沫油拟泡点压力越小,泡沫油阶段越长。随着压力衰竭速度增加,采收率增加,生产气油比减小,油藏压力递减变慢。     

泡沫油油藏数值模拟研究

泡沫油是一种含有大量分散性小气泡的稠油,衰竭开发泡沫油具有产量高、气油比低、地层压力下降缓慢和采收率高等特点。提出了利用数值模拟技术模拟泡沫油的关键方法,并建立了泡沫油数值模型。通过与常规溶解气驱数值模拟结果的比较以及与室内实验结果的拟合,从定性和定量2个方面证明了所建立模型的可靠性,并利用该模型进一步研究了泡沫油的驱油机理。泡沫油油藏开发过程中产生的分散气,一方面增加了原油的流动能力,当平均地层压力降低到泡点压力以下后仍然能够以初始产量生产1a以上;另一方面增加了体系的膨胀能,减缓了地层压力下降速度,地层压力从6.0MPa降低到5.1MPa的时间接近于从10.0MPa降低到6.0MPa的时间。     

稠油冷采泡沫油溶解气驱油藏开发动态数值模拟

稠油注蒸汽等热采开发方式面临着油层出砂、气窜和采油成本高等问题,而稠油冷采过程中形成的泡沫油,则使稠油油藏具有采油速度快、采收率高和生产气油比低等特点。在论述STARS模拟泡沫油机理及模型局限性的基础上,建立了稠油冷采泡沫油溶解气驱油藏模型。模拟结果表明,与常规溶解气驱油藏相比,泡沫油溶解气驱油藏具有生产气油比上升缓慢、累积产油量高等特点;在油相中气泡形成频率一致的情况下,气泡破裂速度越快,生产气油比越大,产油量越低;原油粘度越高,地层渗透率越低,开发效果越好,稳产时间越长。     

Viscosity Behavior of Foamy Oil: Experimental Study and Modeling

Abstract

Heavy oil cold production is faced with the foamy oil phenomenon: while extracted, a heavy crude oil is submitted to a depletion that can induce the formation of dispersed gas bubbles and makes it appear as a foam. This situation results in a change of the flow properties of the live oil that is still debated: correlations predict a decrease or an increase in the gas bubble-dispersed oil viscosity with the gas volume fraction. We attempted to improve the understanding of the foamy oil behavior through rheological measurements. A live oil was depleted inside the pressure cell of a controlled stress rheometer. The occurrence of bubbles was checked and visualized with x-ray scanning experiments. Viscosity was continuously measured using oscillatory and continuous tests. This particular experimental approach allowed us to successfully study the rheological behavior of a foamy oil in relationship with the two main parameters, which are the composition and the viscosity of the crude oils. A theoretical model describing the viscosity of a foamy oil has been established. It takes into account both first-order kinetics of appearance and release of bubbles in oil and a basic suspension model. Results from this model are in agreement with experimental data obtained from different heavy crude oils.     

Visual Experimental Study of the Factors Affecting the Stability of Foamy Oil Flow

Abstract

Some of the heavy oil reservoirs in Canada, Venezuela, and China under solution gas drive illustrate important features: low gas–oil ratio, high production rates, and very high ultimate oil recovery. It is generally believed that the foamy oil flow is one of the important mechanisms contributing to these unusual performances. A series of two-dimensional etched glass micromodel experiments was carried out to gain an insight into the processes involved in foamy oil flow. In these experiments, the bubble nucleation, migration, coalescence, breakup, and ultimate generation of a continuous gas phase can be observed continuously. On the basis of the experimental analysis, there are two bubble-point pressures in the foamy oil: One is the true bubble-point pressure, and the other is the pseudo-bubble-point pressure. The greater the difference between these two bubble-point pressures, the more stable the foamy oil flow is and the greater the contribution to oil recovery from the foamy oil drive mechanism is. The visualization experimental results show that there are many factors affecting the stability of the foamy oil, including pressure depletion rate, crude oil viscosity, temperature, dissolved gas–oil ratio, etc.     

THAI技术开发厚层稠油油藏井网参数优选

厚层稠油油藏原油黏度高、埋藏深、油藏流体流动性差、动用程度低,采用THAI(从端部到跟部注空气)技术可提高该类油藏的采收率。通过数值模拟对排状布井方式的井网参数进行优选,得出影响因素的敏感性强弱依次为生产井水平段长度、注气量、井距、注气井到生产井水平段端部的距离。在此基础上,进一步分析厚层稠油油藏中不同布井方式的开发效果。结果表明:随着燃烧前缘向前推进,生产井中会产生气窜通道;方案2VIHP的采油速度和采收率优于其他方案;层厚是影响热量传递的重要因素;垂直注气井的开采效果优于水平注气井。     

泡沫油流变特性及其影响因素实验

在常规原油流变特性测试系统基础上,研制了泡沫油流变特性测试装置,实现了不同实验条件下泡沫油流变特性的测试和泡沫油图片的动态观察。实验装置包括泡沫油生成系统、流变特性测试系统和图像采集系统。从采集到的泡沫油图片可以看出,气泡在原油中高度分散,形成了稳定的泡沫油流动状态。泡沫油黏度影响因素分析表明,随着气泡等效平均直径的增大,其对泡沫油黏度的影响逐渐增强;泡沫油黏度与泡沫质量近似呈线性正相关关系;泡沫油黏度随剪切速率的增大而逐渐降低,表现出明显的剪切变稀特性,且随泡沫质量增大,泡沫油流动特性指数减小,即泡沫油的非牛顿特性强于活油。     

Successful simulation of solution gas drive in heavy oils using conventional modeling

Detailed investigations into the production behavior of heavy oil reservoirs under foamy solution gas drive have been conducted extensively in the past. Historically, two approaches have been used to explain and model the solution gas drive in heavy oil reservoirs. The first approach is the base of foamy oil models in which solution gas drive is governed by parameters such as compressibility, viscosity, nonequilibrium phenomena, and the supersaturation. In the second approach, conventional modeling, which we show to be suitable for the history matching and prediction of the production data and macroscopic modeling of a series of depletion experiments (using a live combination of heavy oil and methane gas in a three-dimensional rectangular laboratory model), the foamy oil flow mechanism, dispersed flow of gas and the supersaturation are nonexistent. The conventional modeling uses parameters such as critical gas saturation, very low gas relative permeability, and the assumption of no supersaturation in the reservoir.