Visualization of the Effect of Porous Media Wettability on Polymer Flooding Performance through Unconsolidated Porous Media using Magnetic Resonance Imaging

Abstract

Waterflooding effectiveness depends on the mobility ratio of the injected water to displaced fluids, and on the geologic heterogeneity of the reservoir rock. Rock wettability also affects the performance of water and polymer flooding. It is generally recognized that waterflooding in a water-wet reservoir is more efficient than waterflooding in an oil-wet reservoir. Polymer absorption/retention in porous media is also affected by rock wettability. The Centric Scan SPRITE Magnetic Resonance Imaging (MRI) technique is applied in this work to visualize the performance of polymerflooding and to quantify in situ fluid saturation distribution in rocks with wettability ranging from strongly water-wet to preferentially oil-wet.     

注水开发油藏润湿性变化及其对渗流的影响

为提高水驱开发油藏采收率预测精度,研究了油藏岩石润湿性与相对渗透率之间的变化规律及其对两相渗流的影响。采用室内润湿性实验测定方法,对水驱开发油藏润湿指数与含水饱和度的关系进行了定量表征,导出了适合润湿性变化型油藏的两相渗流方程,建立了变润湿性水驱开发油田的采收率预测方法。润湿实验结果表明:所测岩心的润湿指数的对数与取心油层的含水饱和度呈近似线性关系。相对渗透率实验所测的代表低含水期到高含水期岩心的油水两相等渗点对应的含水饱和度由41%增加到53%,亲水程度增强。一维模型计算结果表明,含水率达到98%时,油润湿和强水润湿性油藏的预测采收率分别为52.7%和73.3%。研究揭示的水驱油藏岩石润湿性变化规律和建立的数学模型,可为更加准确地预测水驱油采收率提供参考。      

黏弹性流体分形多孔介质渗流数学模型及计算方法

为了研究黏弹性流体在多孔介质中的渗流规律,将分形理论应用于黏弹性流体的渗流模拟中,通过推导黏弹性流体有效黏度关系式,得到了多孔介质的分形孔隙度和分形渗透率表达式,进一步建立了黏弹性流体分形多孔介质渗流数学模型。使用有限差分方法对黏弹性流体分形多孔介质渗流数学模型进行了数值求解,并利用拉格朗日插值法求得了稳定流状态不同压力下的流量。通过对大庆油田采油四厂5口复合驱井进行实例计算的结果表明,黏弹性流体分形多孔介质渗流数学模型计算所得产液量与实测产液量之间的平均相对误差较小,该模型具有一定的实用价值。     

表面活性剂对低渗油湿灰岩表面性质及渗吸行为的影响

裂缝发育的低渗灰岩储层，当基质岩块为混湿及油湿时，毛细渗吸驱油作用很弱。本工作采用毛管上升、渗吸及相对渗透率曲线方法，在62℃下研究了CTAB和SDBS溶液对油湿灰岩表面性质及渗吸行为的影响。浓度为700mg／L时，SDBS溶液与原油间的界面张力为0．035mN／m，而CTAB溶液为1．25mN／m；随着浓度增大，SDBS溶液使亲油的毛管表面润湿接触角缓慢减小，而CTAB溶液使润湿接触角大幅减小，在与最大吸附量对应的浓度下润湿接触角有最低值；亲油岩心在CTAB溶液中的渗吸驱油速度较SDBS溶液中的渗吸驱油速度高；相渗曲线表明，与亲油岩心／SDBS溶液体系相比，亲油岩心／CTAB溶液体系的油相相对渗透率较高而水相相对渗透率较低。因此，CTAB类阳离子表面活性剂可望用于该类油藏的开发。讨论了相关的机理。图6参10。     

低渗透裂缝性砂岩油藏多孔介质渗吸机理研究

低渗透裂缝性油田开发比较复杂,其中水的自发渗吸对原油的开采十分有利。影响渗吸的因素有岩样大小、岩石特性(孔隙度、渗透率)、流体特性(密度、粘度和界面张力)、润湿性、初始含油饱和度以及边界条件等。利用常规室内渗吸实验和先进的核磁共振技术,系统地研究了低渗透裂缝性砂岩油藏中以上各种因素对渗吸的影响程度,得到了一些变化规律,从而为低渗透裂缝性砂岩油藏的开发提供了理论根据.     

Investigating the performance of hot water injection in geostatistically generated permeable media

The study investigates the performance of hot water flooding compared to conventional water flooding in recovering heavy oil from heterogeneous reservoirs through fine-mesh numerical simulations. A total of 16 permeability maps were generated geostatistically to cover a wide range of reservoir heterogeneity. Two measures of heterogeneity were used to characterize the permeability maps: the Dykstra–Parsons coefficient and the spatial correlation length. Extensive three-dimensional, fine-mesh simulation runs were performed to study the functional relationships between several design parameters and the oil recovery obtained during hot water flooding. These results were then compared to those obtained by conventional water flooding. Parameters which were investigated include: (1) degree of reservoir heterogeneity (2) injected fluid temperature (3) well configurations, and (4) viscosity ratio. Results showed that these parameters play important roles in the displacement behavior of heavy oil, with reservoir heterogeneity having more significant effects. It is proven that hot water flooding can be more effective than conventional one by considering the critical values of the above studied parameters. The paper also shows the conditions that can be detrimental to hot water flooding.     

匹配追踪法在碳酸盐岩流体检测中的应用——以哈萨克斯坦楚-萨雷苏盆地为例

由于碳酸盐岩储层非均质性强、结构复杂,给含油气性的正确判识带来了较大困难.匹配追踪是目前较为有效的一种高精度时频域分解技术,基于含气储层的频率特性构造的流体活动性属性参数,可较好指示碳酸盐岩储层含油气的变化.以哈萨克斯坦楚-萨雷苏盆地ASA研究区碳酸盐岩储层为例,应用匹配追踪方法对地震资料进行高精度时频分解,根据地震波入射饱和流体多孔介质波动方程,建立流体活动属性与频率关系式,获得与流体性质密切相关的流体因子,对含气储层分布范围进行预测.经钻探证实,单井吻合率达86.3 % .这一预测成果对该地区的油气勘探具有重要指导作用,也为今后碳酸盐岩储层的勘探提供了一种很好的方法.     

岩性、孔隙及其流体变化对岩石弹性性质的影响

根据Gassmann方程推导出了流体模量与含流体岩石体积模量之间的关系。该关系反映出在流体置换过程中,流体模量及岩性变化等因素对含流体岩石弹性性质的影响。通过理论计算与分析表明,流体变化对刚性较强的(硬)岩石影响较小,而对刚性较小的(软)岩石影响较大。岩石孔隙度越低,含流体岩石体积模量对流体变化愈敏感。即地震波的纵波速度随孔隙度增大而减小。岩石孔隙度及流体模量较小时,纵波速度对流体变化比较敏感。通过对实际岩石样品进行流体驱替实验,发现实验结果与理论分析相一致。     

Evaluation of gas wettability and its effects on fluid distribution and fluid flow in porous media

The special gas wettability phenomenon of reservoir rocks has been recognized by more and more researchers.It has a significant effect on efficient development of unconventional reservoirs.First,based on the preferentially gas-covered ability and surface free energy changes,definition and evaluation methods have been established.Second,a method for altering rock wettability and its mechanisms have been studied,surface oriented phenomena of functional groups with low surface energy are the fundamental reason for gas wettability alteration of rock.Third,the effect of gas wettability on the surface energy,electrical properties and dilatability are investigated.Last,the effects of gas wettability on capillary pressure,oil/gas/water distribution and flow are investigated with capillary tubes and etchedglass network models.The gas wettability theory of reservoir rocks has been initially established,which provides theoretical support for the efficient production of unconventional reservoirs and has great significance.     

新型声波探头的研制与应用

针对目前常用的声波换能器存在测试不方便,横波首波位置难以确定且不能模拟地层条件等问题,研制了新型声波探头。新型探头将纵横波晶片合为一体,并且互不影响,能有效抑制纵波干扰,可以明确判断出横波的首波位置。该声波探头中间的不锈钢引流管线可以改变岩心孔隙流体性质和孔隙压力。将声波探头安装在岩心夹持器中,就可在高温(150℃)高压(90MPa)下模拟地层条件的同时获取岩心的纵横波波形,读出纵横波时差,进而算出所测岩心的纵横波速度。新型声波探头具有结构简单、精确度高等优点,可用于岩心力学参数分析以及流体识别等领域。     

高温高压条件下油藏内源微生物微观驱油机理

为研究内源微生物微观驱油机理,在模拟油藏高温高压（60℃、10 MPa）条件下,以油田提取的内源微生物群落及其代谢产物作为驱油介质,利用研制的微观仿真光刻蚀可视模型,对水驱、微生物驱油过程中剩余油形态及流动特征进行显微观察和分析;并应用测试和图像处理技术,定量考察微生物微观驱油效果。研究结果表明：高温高压油藏条件下,内源微生物具有一定活性,且驱油效果较好;微生物被激活后,能有效启动不同类型剩余油,并可与代谢产物共同作用于水驱所无法波及到的盲端孔道,置换出剩余油,增强了原油的流动能力,同时可提高采收率。微生物微观驱油机理可归结为：微生物对原油的“啃噬”、降解;产生生物气溶解于原油,降低原油黏度;产生生物表面活性剂层层剥离、乳化剩余油,改变孔隙介质表面的润湿性等。     

油水井异常变化机理与天然地震前兆

济阳坳陷惠民凹陷中央断裂带的油水井产液异常是天然地震前兆。地震的孕育过程是区域地应力场变化的过程，导致地下储集层孔隙流体压力变化，使油层与井孔间的压差增大，造成井孔中流体的流速、流量异常变化，并使地下流体的溶解度变化，引起其物理和化学性质的变化。     

基于岩石物理实验的储层与孔隙流体敏感参数特征——以珠江口盆地东部中-深层碎屑岩储层为例

岩石物理实验是研究储层地震响应特征的重要手段,利用实验测试不同类型、含不同孔隙流体岩石样品的岩石物理参数,可为寻找优质储层及烃类流体的敏感性参数提供实验依据。根据珠江口盆地中-深层碎屑岩储层油气勘探的需要,选取珠一坳陷的惠州凹陷、陆丰凹陷和西江主洼,珠二坳陷的白云主洼、白云东洼和番禺低隆起等地区13口井的碎屑岩储层样品,开展了岩石物理参数的实验测试研究。通过地层压力条件下不同岩性、不同物性、不同孔隙流体饱和度的测试分析,得到样品的储层物性特征和岩石物理参数特征及岩样含不同孔隙流体饱和度时的地震响应特征。测试结果表明：岩样具有高孔中渗、中孔中低渗、低孔低渗、特低孔低渗等多种储层物性特征,物性具有明显的差异;岩样纵/横波速度、杨氏模量、剪切模量、体积模量、拉梅常数等岩石物理参数与孔隙度、渗透率、密度之间具有较高的相关度;岩样随着含水饱和度的提高,其拉梅常数、体积模量、泊松比、纵波波阻抗、纵波速度、纵/横波速度比随之增加,变化幅度大,表现出对含水/气、含水/油饱和度的变化比较敏感。岩样的横波速度、横波波阻抗、剪切模量变化较小,表现出对含水/气、含水/油饱和度的变化敏感性较弱。ρf、λρ、λρ ·μρ、σ、Z_p-Z_s等流体识别因子具有很强的气水识别能力,也具有一定的油水识别能力。不同流体识别因子的组合模板,具有较好的识别气、水、油的效果,且识别海相储层孔隙流体的效果明显好于陆相储层。     

CO2注入对储层多孔介质及赋存流体性质影响实验研究

明确CO2注入对储层多孔介质及赋存流体性质的影响规律是分析油藏条件下CO2驱油机理和确定提高采收率潜力的基础。开展了不同压力条件下CO2与岩心静态接触实验和岩心驱替实验,测试了CO2注入前后岩心物性及微观孔喉结构和地层流体主要离子含量、采出原油组分、黏度及其沥青质含量等特征参数。实验结果表明:CO2注入压力由5 MPa升至20 MPa过程中,储层多孔介质平均孔隙度增大19.16%,平均渗透率降低11.23%,直径为100~150μm的孔隙空间增加9.73%,直径小于1.5μm的喉道空间增加15.83%,岩心亲水性显著增强;随着CO2在不同压力下的逐渐注入,地层水中Ca^2+和HCO-3含量增大,采出原油中C 5~C 33组分含量呈现先增大后基本不变的规律,采出原油黏度及其沥青质含量呈现先迅速降低,后保持不变的规律。     

油气地下渗流发展评述

回顾地下渗流理论的诞生及其发展历程,对比地下渗流力学和粘性流体力学,指出影响油气渗流理论发展的主要因素,总结地下渗流力学的发展规律和发展路线。     

Reservoir characterization utilizing core and wire line logging data for Kareem sandstone,Ashrafi oil Field,Gulf of Suez,Egypt

This study aims to integrate core and wire line logging data for evaluation of Kareem sandstone (Middle Miocene) in Ashrafi Field, Gulf of Suez, Egypt. The study has been carried out on seven wells ASHRAFI_A_01_ST, ASHRAFI_A_02_ST, ASHRAFI_H_IX_ST2, ASHRAFI_I_1X_ST, ASHRAFI_K_1X, ASHRAFI_SW_04, ASHRAFI_SW_06, by using wire line logging data and core data. The interpretation of these data has been done by using Interactive Petrophysics software.The Net pay thickness ranges between 17?ft to about 110?ft, porosity varies from 13% to 26%, permeability from 125?mD to about 960?mD, water saturation from 19% to about 50% and shale content from about 18% to about 56%. The interpretation of the Kareem sandstone (core data for ASHRAFI_SW_04 well) indicates that the average core porosity value is about 17% and the average core permeability is about 800?mD, which indicate a suitable reservoir. The porosity increases with the increasing of the permeability and the relationship between them has good correlation coefficient of 0.81 for wire line logging data set and 0.85 for core data set. These relations can be used to determine permeability from porosity for sandstone of Kareem Formation.The new development area for Ashrafi Field can be determined where there are two zones: one in the Middle and the other in South west. Stratigraphic correlation chart shows that, the Kareem Formation thickness varies laterally in Ashrafi field so, the new well location could be determined perfectly. The integration between well logging data and core data are very important tools to evaluate the degree of heterogeneity in the Kareem sandstone and storage capacity properties as well as the zone of interest of productivity and perforation.