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1.
储层宏观参数是储层微观参数的宏观体现.以孔隙度、绝对渗透率、相对渗透率等宏观参数作为约束条件,拟合生成网络模拟模型,在此基础上讨论了孔喉半径、喉道半径均质系数、孔喉比、孔喉润湿性、孔喉形状和配位数等微观参数的变化对孔隙度、绝对渗透率和相对渗透率等宏观参数的影响.在影响因素敏感性分析的基础上,确定了引起储层宏观参数变化的...  相似文献   

2.
研究气液非混相驱替过程中的相界面卡断机理及其影响因素在气驱, 气水交替及泡沫驱等提高油气采收率领域具有重要意义. 本文在原始伪势格子玻尔兹曼模型的基础上, 改进流体-流体作用力格式, 添加流-固作用力, 耦合RK状态方程, 并采用精确差分方法将外力添加到LBM框架中. 通过校准模型的热力学一致性以及模拟测试界面张力, 静态平衡接触角及液相在角隅的滞留等一系列两相体系验证模型的准确性. 基于改进的伪势格子玻尔兹曼模型, 在孔-喉-孔系统中开展气液非混相驱替模拟, 结果表明: 卡断现象与驱替压差, 孔喉长度比及孔喉宽度比有关, 只有当驱替压差处于一定范围内时, 气液两相驱替过程中才会发生卡断现象; 当驱替压差大于临界驱替压差上限时, 即使达到了经典静态准则所预测的卡断条件, 卡断也会被抑制; 当驱替压差小于临界驱替压差下限时, 无法克服毛管“钉扎”作用, 形成无效驱替. 对于固定孔喉宽度比的孔-喉-孔结构, 随着孔喉长度比的增大, 发生卡断现象的驱替压差范围增大; 对于固定孔喉长度比的孔-喉-孔结构, 随着孔喉宽度比的减小, 发生卡断现象的驱替压差范围增大.   相似文献   

3.
聚合物驱油作为一种重要的三次采油方法,在国内外油气田开发中得到了广泛应用.聚合物驱油效果的好坏取决于多种因素,其中很重要的一个因素是聚合物的注入能力,这一因素直接决定了聚合物驱油的成败.本文利用实验方法研究了聚合物的分子质量、岩样的渗透率以及注入速度等因素对聚合物注入能力的影响.结果表明,聚合物溶液具有粘弹性,注入速度增大,注入性变差.同时聚合物分子量越大,岩心渗透率越低,聚合物注入性越差.对于孤岛中一区,平均孔隙半径与聚合物分子折算半径之比大于10时,聚合物可顺利注入地层.研究结果可用于指导现场聚合物的选取,从而有效保证聚合物的注入能力,使聚合物驱油达到预期效果.  相似文献   

4.
将多孔介质简化为一簇变截面毛管束,根据多孔介质的颗粒直径、颗粒排列方式、孔喉尺度 比及束缚水饱和度,计算出变截面毛细管的喉道半径和孔隙半径. 在考虑多孔介质喉道和孔 隙中单个气泡的受力和变形基础上,利用动量守恒定理,推导出单个孔隙单元内液相的压力 分布和孔隙单元两端的压差计算公式,最终得到多孔介质的压力分布计算公式. 利用长U型 填砂管对稳定泡沫的流动特性进行了实验研究. 研究结果表明:稳定泡沫流动时多孔介质中 的压力分布呈线性下降,影响泡沫在多孔介质中流动特性的因素包括:多孔介质的孔喉结构、 泡沫流体的流量和干度、气液界面张力、气泡尺寸,其中孔喉结构和泡沫干度是影响泡沫封 堵能力的主要因素. 关键词: 稳定泡沫;多孔介质;变截面毛管;流动;表观粘度;压力分布;实验研究  相似文献   

5.
用于聚合物驱油的抽油杆动力学分析   总被引:1,自引:0,他引:1  
聚驱井与水驱井相比杆管偏磨更加严重,聚驱井采出液的法向力是加剧偏磨 的重要因素之一. 根据非牛顿流体力学理论,采用上随体Maxwell模型,建立了法向力计算 模型,确定了井筒内法向力的分布规律,并将此法向力施加在抽油杆的瞬态动力学 模型中; 考虑实际边界条件,采用有限元法对聚驱抽油杆进行了分析计算. 并对FU081801 井模拟计算进行验证,模拟结果与作业检测结果吻合较好,证明了该方法的可行性. 通过此 方法可预测出聚驱井杆管的偏磨位置以及聚合物浓度对抽油杆偏磨的影响程度.  相似文献   

6.
基于三维网络模型的水驱油微观渗流机理研究   总被引:11,自引:0,他引:11  
利用逾渗网络模型在微观水平进行随机模拟来研究水驱油的微观渗流规律,通过模型计 算结果与油水稳态相对渗透率驱替实验结果对比验证了网络模拟的有效性. 在此基础上,讨 论了在不同润湿条件下、水驱不同阶段的剩余油微观分布规律. 将剩余油分布形态归纳为4 种状态:孤粒/孤滴状、斑块状、网络状和油水混合状态. 研究表明,网络状剩余油的块数 较少,但所占体积比例较大. 随着剩余油饱和度的降低,最大网络状油所占孔隙数减少,剩 余油饱和度在40{\%}$\sim$50{\%}附近开始以较快速度减少. 润湿性不仅影响驱油效率,也影响剩余油分布形态. 在驱替过程中,剩余油分布总的变化趋势是逐渐趋于分散.  相似文献   

7.
研究纳米尺度时开裂椭圆孔的III型断裂性能。基于表面弹性理论和保角映射技术,利用复势函数理论获得了缺陷(裂纹和椭圆孔)周围应力场和裂纹尖端应力强度因子的闭合解答。所得结果具有一般性,许多已有和新的解答可由本文退化的特殊情形得到。利用解析结果讨论了缺陷的绝对尺寸、椭圆孔的形状比以及裂纹的相对尺寸对应力强度因子的影响。结果表明:考虑表面效应且缺陷尺寸在纳米尺度时,应力强度因子具有显著的尺寸依赖效应;应力强度因子随椭圆孔形状比的变化规律受缺陷表面常数的影响;缺陷表面效应的影响取决于椭圆孔的形状比,非常大的形状比屏蔽了表面效应的影响;裂纹相对尺寸非常小时表面效应影响较弱,裂纹相对尺寸较大时表面效应较为明显。  相似文献   

8.
地下核爆炸后会在地表产生下陷弹坑、塌陷带等不可逆变形爆炸后效应,利用地表形变信息对地下核试验进行有效监控和评估具有十分重要的意义。基于考虑重力影响的地下强爆炸塌陷成坑相似理论,利用陆军工程大学自主研制的地下爆炸效应真空室模拟试验装置,对2017年9月3日朝鲜地下核试验诱发的地表不可逆变形进行了模型试验。试验结果表明,地表塌陷带半径为257 m,下陷弹坑的半径为154 m,与美国、前苏联等国家已有的地下核试验经验公式的数据结果基本相当,并且符合天基雷达TS-InSar卫星监测数据的估算结果,验证了地下爆炸真空室模型试验在地下强爆炸诱发地表不可逆变形区域模拟和评估的可行性,成为有效补充地震波和卫星监测地下强爆炸的一种研究手段。  相似文献   

9.
张毅  薛世峰  韩丽美  周博  刘建林  贾朋 《力学学报》2021,53(6):1671-1683
损伤本构模型对研究材料的断裂失效行为有重要意义, 但聚合物材料损伤演化的定量表征实验研究相对匮乏. 通过4种高密度聚乙烯(high density polythylene, HDPE)缺口圆棒试样的单轴拉伸实验获得了各类试样的载荷-位移曲线和真应力-应变曲线, 采用实验和有限元模拟相结合的方法确定了HDPE材料不同应力状态下的本构关系, 并建立了缺口半径与应力三轴度之间的关系;采用两阶段实验法定量描述了4种HDPE试样单轴拉伸过程中的弹性模量变化, 并建立了基于弹性模量衰减的损伤演化方程, 结合中断实验和扫描电子显微镜分析了应力状态对HDPE材料微观结构演化的影响. 结果表明缺口半径越小, 应力三轴度越大, 损伤起始越早、演化越快; 微观表现为: 高应力三轴度促进孔洞的萌生和发展, 但抑制纤维状结构的产生;基于实验和有限元模拟获得的断裂应变、应力三轴度、损伤演化方程等信息提出了一种适用于聚合物的损伤模型参数确定方法, 最后将本文获得的本构关系和损伤模型用于HDPE平板的冲压成形模拟, 模拟结果与实验结果吻合良好.   相似文献   

10.
油藏复杂驱动体系物理模拟相似准则研究进展   总被引:7,自引:0,他引:7  
综述了水驱油、化学驱油、蒸汽驱、混相驱及非混相驱等复杂油藏驱替体系物理模拟相似准则的研究现状. 系统介绍了相似参数敏感性分析方法, 定义了表征目标函数对相似参数依赖程度的敏感因子, 结合数值方法便可定量地确定复杂体系主要相似参数, 并实际应用于工程问题. 讨论了水驱和聚合物驱物理模拟应优先满足的相似准则及其随参数范围的变化.  相似文献   

11.
The microscopic oil displacement mechanism in viscoelastic polymer flooding is theoretically analyzed with mechanical method. The effects of viscoelasticity of polymer solution on such three kinds of residual oil as in pore throat, in sudden expansion pore path, and in dead end are analyzed. Results show that the critical radius of mobile residual oil for viscoelastic polymer solution is larger than that for viscous polymer solution, which makes the oil that is immobile in viscous polymer flooding displaced under the condition of viscoelastic polymer solution. The viscous polymer solution hardly displaces the oil in dead ends. However, when the effect of viscoelasticity is considered, the residual oil in sudden expansion pore paths and dead ends can be partly displaced. A dimensionless parameter is suggested to denote the relative dominance of gravity and capillary pressure. The larger the dimensionless parameter, the more accurate the increment expressions.  相似文献   

12.
A network model is established through the techniques of image reconstruction, a thinning algorithm, and pore–throat information extraction with the aid of an industrial microfocus CT scanning system. In order to characterize actual rock pore–throat structure, the established model is modified according to the matching of experimental factors such as porosity, permeability, and the relative permeability curve. On this basis, the impacts of wetting angle, pore radius, shape factor, pore–throat ratio, and coordination number as applied to microscopic remaining oil distribution after water flooding are discussed. For a partially wetting condition, the displacement result of a water-wet pore is somewhat better than that of an oil-wet pore as a whole, and the possibility of any remaining oil is relatively low. Taking the comprehensive effects of various factors into account, a prediction method of remaining oil distribution is presented through the use of fuzzy comprehensive evaluation. It is seen that this method can predict whether there is remaining oil or not in the pore space with satisfactory accuracy, which is above 75%. This method thus provides guidance for a better understanding of the microscopic causes of the remaining oil.  相似文献   

13.
We investigate whether upscaling errors for EOR simulation can be reduced by an upscaling–static-downscaling method where the scales of simulation for the pressure and saturation/concentration switch between coarse simulation model and fine geological model. We apply a static downscaling that has been previously shown to be reliable for water flooding. We use the same algorithm of static downscaling for EOR processes that have been used for water flooding. Different EOR processes are considered: polymer, surfactant and thermal. This range of flooding processes ensures that we are examining more physically complicated systems than water flooding. For these processes, one major difference from water flooding is existence of a secondary front. The effective capturing of this front is a criterion of accuracy for upscaling because, for this front, the coupling of dispersion with the fractional flow creates excessive smearing. A scheme for numerical dispersion control is implemented to both upscaled and downscaled models to determine and reduce the sensitivity to dispersion errors.  相似文献   

14.
A polymer solution with a transient network structure due to the entanglement of long chain molecules exhibits a viscoelastic behavior when it flows through a tortuous and diverging/converging channel in porous media. A constitutive equation is first developed to represent the viscoelastic behavior of polymer solutions in this article. Then a 3D viscoelastic polymer flooding model is established to examine the effect of elasticity of polymers on EOR (enhanced oil recovery). The model is validated in comparison with laboratorial coring data. The simulated results show that the oil recovery of viscoelastic polymer flooding can be enhanced by larger displacement efficiency due to its microscopic roles. In the meanwhile, the injection pressure required increases correspondingly if the elastic effect is significant. Relaxation time as a major characteristic parameter of viscoelastic polymer plays a decisive role, and therefore the HPAM (partially hydrolyzed polyacrylamide) with evident elastic property is recommended in chemical flooding.  相似文献   

15.
In this paper, a microscopic visualization experiment is conducted to explore the heterogeneous flow pattern of micro polymer particles in micron pore. A capillary bundle network model for micro polymer particles in porous media is established. The migration and retention mechanism of polymer particles can be clearly observed in the experiment and simulated with this numerical model. The result demonstrates that the block of large particles is one of the main factors by which micro polymer particles increase the flow resistance. The simulation results are consistent with the experimental results.  相似文献   

16.
In spite of the role of alkali in enhancing oil recovery (EOR), the formation of precipitation during alkaline-surfactant-polymer (ASP) flooding can severely do harm to the stratum of oil reservoirs, which has been observed in situ tests of oil fields such as scale deposits found in oil stratum and at the bottom of oil wells. On the other hand, remarkable variation of stratum parameters, e.g., pore radius, porosity, and permeability due to scale formation consider-ably affects seepage flow and alkaline flooding process in return. The objective of this study is to firstly examine these mutual influential phenomena and corresponding mecha-nisms along with EOR during alkaline flooding when the effects of precipitation are no longer negligible. The chem-ical kinetic theory is applied for the specific fundamental reactions to describe the process of rock dissolution in silica-based reservoirs. The solubility product principle is used to analyze the mechanism of alkali scale formation in flooding. Then a 3D alkaline flooding coupling model accounting for the variation of porosity and permeability is established to quantitatively estimate the impact of alkali scales on reser-voir stratum. The reliability of the present model is verified in comparison with indoor experiments and field tests of the Daqing oil field. Then, the numerical simulations on a 1/4 well group in a 5-spot pattern show that the precipitation grows with alkali concentration, temperature, and injection pressure and, thus, reduces reservoir permeability and oil recovery correspondingly. As a result, the selection of alkali with a weak base is preferable in ASP flooding by tradeoff strategy.  相似文献   

17.
Chemical flooding is one of the effective technologies to increase oil recovery of petroleum reservoirs after water flooding. Above the scale of representative elementary volume (REV), phenomenological modeling and numerical simulations of chemical flooding have been reported in literatures, but the studies alike are rarely conducted at the pore-scale, at which the effects of physicochemical hydrodynamics are hardly resolved either by experimental observations or by traditional continuum-based simulations. In this paper, dissipative particle dynamics (DPD), one of mesoscopic fluid particle methods, is introduced to simulate the pore-scale flow in chemical flooding processes. The theoretical background, mathematical formulation and numerical approach of DPD are presented. The plane Poiseuille flow is used to illustrate the accuracy of the DPD simulation, and then the processes of polymer flooding through an oil-wet throat and a water-wet throat are studies, respectively. The selected parameters of those simulations are given in details. These preliminary results show the potential of this novel method for modeling the physicochemical hydrodynamics at the pore scale in the area of chemical enhanced oil recovery.  相似文献   

18.
宋文辉  姚军  张凯 《力学学报》2021,53(8):2179-2192
页岩储层孔隙结构复杂, 气体赋存方式多样. 有机质孔隙形状对受限空间气体吸附和流动规律的影响尚不明确, 导致难以准确认识页岩气藏气体渗流机理. 为解决该问题, 本文首先采用巨正则蒙特卡洛方法模拟气体在不同形状有机质孔隙(圆形孔隙、狭长孔隙、三角形孔隙、方形孔隙)内吸附过程, 发现不同形状孔隙内吸附规律符合朗格缪尔单层吸附规律, 分析了绝对吸附量、过剩吸附浓量、气体吸附参数随孔隙尺寸、压力的变化, 研究了孔隙形状对气体吸附的影响. 在明确不同形状有机质孔隙内气体热力学吸附规律基础上, 建立不同形状有机质孔隙内吸附气表面扩散数学模型和考虑滑脱效应的自由气流动数学模型, 结合分子吸附模拟结果研究了不同孔隙形状、孔隙尺寸有机质孔隙内吸附气流动与自由气流动对气体渗透率的贡献. 结果表明, 狭长孔隙内最大吸附浓度和朗格缪尔压力最高, 吸附气表面扩散能力最弱. 孔隙半径5 nm以上时, 吸附气表面扩散对气体渗透率影响可忽略. 本文研究揭示了页岩气藏实际生产过程中有机质孔隙形状对页岩气吸附和流动能力的影响机制.   相似文献   

19.
A novel concept for modeling pore-scale phenomena included in several enhanced oil recovery (EOR) methods is presented. The approach combines a quasi-static invasion percolation model with a single-phase dynamic transport model in order to integrate mechanistic chemical oil mobilization methods. A framework is proposed that incorporates mobilization of capillary trapped oil. We show how double displacement of reservoir fluids can contribute to mobilize oil that are capillary trapped after waterflooding. In particular, we elaborate how the physics of colloidal dispersion gels (CDG) or linked polymer solutions (LPS) is implemented. The linked polymer solutions consist of low concentration partially hydrolyzed polyacrylamide polymer crosslinked with aluminum citrate. Laboratory core floods have shown demonstrated increased oil recovery by injection of linked polymer solution systems. LPS consist of roughly spherical particles with sizes in the nanometer range (50–150 nm). The LPS process involve mechanisms such as change in rheological properties effect, adsorption and entrapment processes that can lead to a microscopic diversion and mobilization of waterflood trapped oil. The purpose is to model the physical processes occurring on pore scale during injection of linked polymer solutions. A sensitivity study has also been performed on trapped oil saturation with respect to wettability status to analyze the efficiency of LPS on different wettability conditions. The network modeling results suggest that weakly wet reservoirs are more suitable candidates for performing linked polymer solution injection.  相似文献   

20.
Many heavy oil reservoirs contain discontinuous shales which act as barriers or baffles to flow. However, there is a lack of fundamental understanding about how the shale geometrical characteristics affect the reservoir performance, especially during polymer flooding of heavy oils. In this study, a series of polymer injection processes have been performed on five-spot glass micromodels with different shale geometrical characteristics that are initially saturated with the heavy oil. The available geological characteristics from one of the Iranian oilfields were considered for the construction of the flow patterns by using a controlled-laser technology. Oil recoveries as a function of pore volumes of injected fluid were determined from analysis of continuously recorded images during the experiments. We observed a clear bypassing of displacing fluid which results in premature breakthrough of injected fluid due to the shale streaks. Moreover, the results showed a decrease of oil recovery when shales’ orientation, length, spacing, distance of the shale from production well, and density of shales increased. In contrast, an increase of shale discontinuity or distance of the shale streak from the injection well increased oil recovery. The obtained experimental data have also been used for developing and validating a numerical model where good matching performance has been observed between our experimental observations and simulation results. Finally, the role of connate water saturation during polymer flooding in systems containing flow barriers has been illustrated using pore level visualizations. The microscopic observations confirmed that besides the effect of shale streaks as heterogeneity in porous medium, when connate water is present, the trapped water demonstrates another source of disturbance and causes additional perturbations to the displacement interface leading to more irregular fingering patterns especially behind the shale streaks and also causes a reduction of ultimate oil recovery. This study reveals the application of glass micromodel experiments for studying the effects of barriers on oil recovery and flow patterns during EOR processes and also may provide a set of benchmark data for recovery of oil by immiscible polymer flood around discontinuous shales.  相似文献   

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