低渗透油层润湿性对油水两相渗流规律的影响

油层润湿性是影响油水两相渗流规律的重要因素，它决定着水驱油方式和残余油的分布形态，亲油岩心室内试验也表明，束缚水下的油相渗透率远低于水相渗透率，根据水驱油试验的前期资料，可以预测油层润湿性和见水后两相流动区间及最终驱油效率。     

润湿性对油水渗流特性的影响

用亲水露头砂制备水测渗透率分别为0.030、0.197、0.508μm2的3组人造柱状岩心,每组岩心分为表面亲水(不处理)、中性润湿(经甲基硅油处理)、亲油(经胜利原油煤油混合油处理)3类,其表面润湿性经切片测定动态接触角确认。分别用矿化度19.4 g/L的模拟胜利地层水和模拟油测定岩心渗透率。相同渗透率岩心的水测渗透率,岩心表面亲水时最高,中性润湿时次之,亲油时最低,变化幅度随渗透率的增大而减小,最大达600倍;油测渗透率则在表面中性润湿时为最高,亲油时次之,亲水时最低。岩心的水驱采收率,以岩心表面中性润湿时为最高,表面亲水时大幅下降,表面亲油时最低,但与表面亲水时相比,降幅不大。认为油润湿是低渗透油藏注水压力高的原因之一,将油藏润湿性转为中性,可提高水(及化学驱油剂)的注入能力。表3参8。     

润湿性对采收率及相对渗透率的影响

通过实验研究了润湿性对采收率及相对渗透率的影响,还研究了利用原油老化控制岩石润湿性的方法。结果表明弱水湿岩石水驱采收率最高,亲水岩石油相相对渗透率高于亲油岩石,原油中极性物质的吸附会影响岩石表面润湿性,油湿性随老化时间增加而增强。     

润湿性对采收率及相对渗透率的影响

通过实验研究了润湿性对采收率及相对渗透率的影响 ,还研究了利用原油老化控制岩石润湿性的方法。结果表明弱水湿岩石水驱采收率最高 ,亲水岩石油相相对渗透率高于亲油岩石 ,原油中极性物质的吸附会影响岩石表面润湿性 ,油湿性随老化时间增加而增强。     

低成本低浓度表面活性剂对润湿性和相对渗透率的影响

将油水界面张力降低几个数量级可以减少表面活性荆驱的成本.本文对使用低成本表面活性剂改变润湿性从而提高原油采收率的潜力进行了研究.表面活性剂改变润湿性的程度可以通过测量接触角和油水相对渗透率来表征.利用表面活性剂改变润湿性的机理,使油层岩心/流体组合产生中间润湿或者混合润湿,最终能大幅度提高原油采收率.     

润湿性对恳东29块稠油油藏注水采收率的影响

利用制备的不同润湿性岩样,系统研究了注入水对这些岩样注水采收率的影响,得到了润湿性对恳东29块油藏注水采收率的影响规律,即随着岩样水湿性的逐渐增强,注水采收率先逐渐增加后缓慢降低;并得到了使注水采收率最高的恳东29块油藏岩石润湿指数值,对有效开发恳东29块稠油油藏具有重要的指导意义。     

不同润湿性砂岩中聚合物吸附滞留对渗流过程的影响

为了研究不同润湿性孔隙中发生聚合物吸附滞留后的流体渗流机制,首先用非稳态法实验研究了亲水岩心和亲油岩心中聚合物吸附前后的油水两相流动过程,然后改进了半渗透隔板法测试油水毛管力实验方法,用常规驱替流程直接测试了聚合物吸附前后油水毛管力.研究表明,聚合物在岩心中吸附能选择性地降低水相相对渗透率;改变孔隙与渗流流体的相互作用,使亲水岩心束缚水饱和度增加,残余油饱和度降低,亲水程度增强,油水毛管力增加,毛管力曲线变陡;使亲油岩心润湿性反转,油水毛管力由负值变为正值;深化了高含水油藏聚合物驱降水增油机理.     

油藏岩石润湿性对采收率的影响

本文综述了油藏岩石润湿性对水驱油采收率影响的两种不同观点：一种认为弱水湿油藏水驱油采收率最高，另一种认为，弱水湿油藏水驱油采收率最高。本文所做理论分析表明，弱水湿油藏水驱油采收率最高较有依据。     

裂缝性底水油藏中水平井两相渗流模型

本文研究裂缝性底水油藏中水平两相渗流问题。在流线不变的假定下，建立了底部注水时双重孔隙介质中水平井油、水两相垂剖面二维渗流的数学模型，并用特征线方法进行了精确求解，给出了裂缝系统和岩块中的含水饱和度分布以及水平井见水时间公式，从而为利用水平井开采裂缝性底水油藏提供了必要的理论基础和计算方法。     

Wettability and Its Effects on Oil Recovery in Fractured and Conventional Reservoirs

Abstract

The lattice Boltzmann method is a relatively new simulation technique of computational fluid dynamic class. Its several advantages such as dealing with complex boundary and incorporating of microscopic interaction make it an alternative and promising numerical scheme for simulating fluid flow in porous media. Three lattice Boltzmann equation models are introduced and used for calculating permeability of a 2D porous media. Analytical solutions of Poiseuille flow between infinite parallel plates is used for validating lattice Boltzmann equation models. In the numerical simulations the effects of grid resolution and viscosity on the predicted permeability are checked.     

The Impact of Surfactants on Wettability Change and Level of Water Imbibition in Relation to EOR in Carbonate Reservoirs

Some anionic, cationic, and nonionic surfactants have been examined on actual reservoir samples. Thin section analysis and core flooding techniques were used for the petrophysical and mineralogical assessments of the rock samples. Spontaneous imbibition experiments were conducted using oil-saturated plugs in combination with reservoir brine and surfactant solutions separately. Capillary pressure measurements were conducted both before and after wettability alteration. Amott-Harvey and USBM wettability indices were determined. Brooks-Corey and Brooks-Corey-Mualem models were used. Among the surfactants a cationic one could best improve the spontaneous imbibition. Fairly good fit was observed between experimental capillary pressure curves and those calculated by Brooks-Corey model.     

水驱低渗透非均质砂岩油藏提高开发效果研究

在水驱低渗透非均质砂岩油藏开发过程中，普遍存在水驱控制程度低、层间及层内矛盾十分突出、低渗透部位的剩余油难以开采等问题。以我国Ｌ油田Ｄ油藏为原型，利用数值模拟方法对其开发过程和过程中存在的主要问题进行了综合研究。研究表明，在低渗透非均质砂岩油藏开发中后期，及时调整井网并实施周期注水，不仅可提高开发效果，而且可以提高最终采收率。     

胡状集油田注水开发对储层的影响

通过对胡状集油田注水开发前后分析化验资料的对比,在注水开发过程中水岩作用试验模拟基础上,结合开发生产实际情况。探讨了其注水开发对储层孔隙度、渗透率、岩石密度、沉积物粒度及孔隙结构的影响。认为在注水开发过程中,由于受注入水的长期冲刷,储层孔隙结构发生了较大的变化,储层孔隙度、渗透率分布范围有所改变。造成了储层平均渗透率的升高。储层物性发生了较大变化。     

石油非达西渗流的新模式

为认识和了解多孔介质中渗流的基本规律,用无因次分析法对岩心的实验数据进行了分析,得出石油渗流的运动形态有5种:超低速、低速、线性达西、亚高速及高速紊流。并在无因次关系曲线上确定出这5种流态相互转化的临界值。归纳出5种流态的数学统一表达式,对超低速和低速2种新的运动形态从物理和力学角度进行分析,推导出启动压力梯度的表达式。通过对非达西渗流模型进行求解,分析出非达西对地下油气渗流的影响。     

不同类型凝析气藏在低渗多孔 介质中的相态及采收率研究

用凝析油含量不同的凝析气分别在PVT筒和长岩心中进行了衰竭实验,并应用超声波测试技术测试了其饱和度以及高温、高压平衡凝析油气相渗曲线和常温、低压常规油气相渗曲线.实验表明,凝析油含量高的凝析气在多孔介质中凝析油的采收率比PVT筒中约高1倍.采用不同相渗曲线及CMG数值模拟软件对长岩心衰竭实验中凝析油的采收率进行了预测,结果表明,造成凝析油采收率差别的主要原因是界面张力导致凝析油气相渗曲线的差别.在数值模拟中,应当使用真实相渗曲线.对于含凝析油低的凝析气藏,多孔介质中定容衰竭凝析油饱和度远高于PVT筒中凝析油采收率,多孔介质中蒸发现象不明显.凝析油饱和度达到最大值后,随压力的降低不再变化,这表明低渗凝析气藏中尽管凝析油含量低,其污染仍然存在,不能忽视.     

Wettability determination of core samples through visual rock and fluid imaging during fluid injection

Reservoir rock wettability is a key factor in oil recovery, as it controls the location, flow, and distribution of reservoir fluids. However, proper assessment of wettability is not an easy task and provides a number of challenges. Wettability is in parts determined by the history of the oil reservoir through mechanisms such as aging and fouling. Hence direct measurements on freshly exposed rock surfaces (e.g. on core plugs) are critical and might not represent the true wettability within the sample. We present a new and fast method for wettability determination based on the optical observation of injected fluids, which allows for wettability determination independent from the surface wettability state of the sample. Fluid behavior within the boundaries of the capillary regime is driven by capillary forces and thus by wettability, which is exploited for our method. We show that a combined optical white-light and fluorescence imaging technique provides excellent contrast for reliable observations. Based on this imaging technique, we successfully distinguish core samples with different internal wettability, independent of their surface state.     

Experimental Studies of the Effects of Permeability Variations on Immiscible Flow

Abstract

The properties of hydrocarbon reservoirs are generally derived from core experiments and use theories of fluid flow that normally assume homogeneous core properties. Reservoirs, however, are generally heterogeneous, and interpretations of the results of these experiments are likely to be unreliable if the core from which the data are derived is heterogeneous. This article examines experimentally immiscible displacement through well-defined permeability heterogeneities, modeled using 2-D visual models packed with clear beads of different permeabilities.

The results indicated that the displacement patterns were dominated by capillary pressure effects and that they were different from those found in miscible systems. This understanding is needed, since in reservoir simulators, the simulator codes must contain the correct physics, and in core analysis, the effluent profiles must be correctly interpreted for sensible predictions.     

水驱砂岩油藏水平井多段流描述及数值模拟研究

合理设计水平井及正确计算其产能,已经成为水平井开发油田能否达到预期效果的重要问题。在水平井渗流规律、产能预测、多段流描述技术、多相流理论以及变质量流理论的基础上,综合采用渗流力学、油藏工程、现代数学和现代计算技术等多学科交叉的方法进行研究,建立水平井井筒-油藏耦合数值模拟的数学模型。采用数值模拟的方法对水平井渗流机理进行了研究,同时,进行水平井油藏数值模拟软件的编制。研究成果的检验与应用表明,提出的基于水平井多段流描述方法的油藏数值模拟模型,可以准确预测水平井的产能,优化水平井参数,指导水平井开发方案制定。