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。     

致密油藏储层驱替特征及开发效果——以鄂尔多斯盆地上里塬地区延长组长7油层组为例

为了研究致密油藏储层驱替特征及其开发效果,以鄂尔多斯盆地上里塬地区上三叠统延长组长7油层组为例,通过测试分析及模拟实验对致密油藏储层的敏感性、渗流特征及水驱油特征进行了分析。结果表明,研究区储层为弱速敏、弱酸敏性,无水敏、盐敏性。致密油藏单相渗流启动压力梯度达2.0 MPa/cm,与渗透率呈负相关;束缚水饱和度和残余油饱和度偏高,共渗区较窄,等渗点较低,含水饱和度增大会导致油相渗透率快速下降。根据其不同驱油阶段含水率和驱油效率的变化,将长7储层的水驱油开发大致划分为无水期、含水快速上升期及高含水期等3不同的开采阶段。无水期驱油效率为18.1%,最终驱油效率较低,仅为31.7%。同时,研究区储层润湿相为弱亲油,对后期的注水开发会产生深远影响。     

高含水后期行列井网周期注水的方法

周期注水能够提高非均质储层的驱油效率.为了改善萨南开发区南六区行列井网厚油层高含水开发后期的开发效果,在剩余油分布规律分析的基础上,应用精细地质研究成果和数值模拟技术,优化行列井网周期注水方案,优选了最佳的注水方式、注水半周期和注水强度,并总结了试验区开展周期注水后动态规律的变化,对行列井网实施周期注水的方法取得了认识:行列井网双井交替注水方式对开发效果的改善明显好于单井交替注水;注水半周期为3个月,注水强度提高1.93倍,周期注水时间为3 a,可提高采收率0.3个百分点.实践证明行列井网高含水后期采取周期注水方式是进一步挖掘剩余油潜力的一项经济有效的调整措施.     

利津油田利33-19井组周期注水数值模拟研究

储层的高度非均质性是制约油田开发的一个主要因素 ,而周期注水是减小储层非均质性不利影响的开发措施。利津油田利 33- 19井组成功地实施了周期注水 ,应用效果显著。应用油藏数值模拟手段对利 33- 19井组周期注水效果进行了分析研究。注水的周期性变化 ,使得油水平面及纵向渗流发生改变 ,引起高渗透层含水饱和度的降低 ,改善了开发效果。日注水量越大 ,高渗透层原油的浸入越多 ,效果越好 ;随开采程度的提高 ,周期注水效果变差 ,这时注水周期应缩短 ,注水幅度应加大     

克拉玛依陆相油砂注水过程中的剪胀诱导渗透率模型

特超稠油油藏普遍采用蒸汽辅助重力泄油(SAGD)方式开发,在前期注水改造阶段储层剪胀扩容导致剪切带产生剪切裂缝,孔隙度和含水/油饱和度发生变化.为了研究注水过程中水的有效渗透率的动态演化规律,考虑孔隙度和含水饱和度随扩容体积应变的变化,通过Kozeny-Poiseuille方程和Touhidi-Baghini方程关联绝...     

致密砂岩气藏润湿性对液相圈闭损害的影响

致密砂岩储层易因外来工作液入侵造成严重的液相圈闭损害,岩石表面润湿性对于液相圈闭损害程度具有重要影响。使用氟碳表面活性剂Zonyl8740处理岩心,降低岩心表面能,制得不同润湿程度的岩心。通过岩心驱替和毛管自发渗吸实验分别研究了气湿岩心和液湿岩心的束缚水饱和度、自吸油水动态;建立初始含水饱和度岩心流动实验,对比了钻井液加入气湿反转剂前后液相圈闭损害率。实验表明,致密砂岩表面由液湿反转为优先气湿可大幅度减弱毛管自吸效应、降低自吸液量和最终滞留饱和度。气湿反转剂可有效减少钻井液对储层液相圈闭损害。对预防致密砂岩储层液相圈闭损害具有一定指导意义。     

靖安油田盘古梁长6油藏控水稳油技术研究及应用

盘古梁长6油藏为构造—岩性油藏,经过长期注水开发,已进入油田开发中含水阶段,综合含水上升,油井水侵严重,影响油藏开发效果.本文针对长6油藏储层物性、储层层内层间非均质性,储层平面非均质性进行了研究,总结了长6油藏注水开发的注采矛盾,分析了控水稳油技术在盘古梁长6油藏注采系统的适用性,进行了控水稳油前后产量变化监测及应用...     

注水开发后期中高渗油藏储层特征分析

本文对注水开发后期中高渗油藏储层特征进行研究。油藏注水开发过程中,各项参数是一个变化的过程,尤其中高渗油藏在高采出程度和高含水的开发后期,储层物性及重要参数发生了明显的变化,本文通过dg油田重要油井的生产历程,对注水开发后期储层物性特征进行总结分析,为后期油藏开发方案编制的准确性提供参考。     

淡水驱替过程中岩石电性实验研究

润湿性是影响储层岩石电阻率的重要因素.实验研究了不同润湿性的岩心淡水驱替过程中岩石电阻率随含水饱和度的变化规律,揭示了油层水淹后不同润湿性岩石的导电机理.实验结果显示水润湿岩心淡水驱替后.随含水饱和度变化电阻率变化曲线呈"U"型或"L"型,亲油岩心电阻率变化曲线呈单调下降趋势.岩石电阻率变化受储层原始润湿性影响.研究结果可为不同润湿性质的油藏水淹层识别和剩余油饱和度评价提供技术支持.     

胜利油田低渗透水驱油藏含水变化特征及影响因素

生产中含水率的变化特征在一定程度上可以反映水驱油效果的好坏。见水早、含水上升快、水驱油效率低等问题一直困扰着低渗透油藏开发。水驱油藏含水率的变化问题属于岩石中油水两相渗流的范畴,含水变化特征必然决定于岩石物性、油水特征和驱动力等因素。针对胜利油田低渗透水驱油藏,通过大量实验数据分析了储层孔隙结构特征、原始含水饱和度、应力敏感性和驱替压力等因素对含水率变化和水驱油效率的影响。研究发现孔隙的连通性是影响含水上升规律的重要因素,而初始含水率主要是由原始含水饱和度决定,适当的控制驱替压力有利于控制含水率,提高水驱油效率。考虑到低渗透储层渗透率的应力敏感性,建议实施超前注水,避免压力下降造成的渗透率伤害,从而利于提高水驱油效率。     

垂向非均质油层周期注水力学机理研究

由油水两相达西定律,推导出垂向非均质油层在周期注水作用下油水纵向窜流由重力窜流、毛管力窜流和附加窜流三部分组成的解析表达式.以J函数为基础,分析了毛管力纵向窜流特性及其对开发效果的影响,阐明了周期注水与稳定注水的本质差别,得出垂向非均质油层周期注水改善开发效果力学机理.     

东濮凹陷油层岩石润湿性的分析

本文认为原油中“非烃+沥青质”是影响油层岩石表面润湿性的关键因素,当其含量达到一定数值时,则油层内的含油孔道岩石表面润湿性可以改变成亲油。当含油孔道岩石表面亲油时,其润湿性受含水饱和度的影响,即含水饱和度低于30%时是亲油、高于40%时是亲水。指出油田随注水开发时间的延长,油层的润湿性将由亲油逐渐改变成亲水。     

Dimensionless groups for three-phase gravity drainage flow in porous media

The downward displacement of oil by gas (either through gas cap expansion or by gas injection) at the crest of the reservoir is an attractive method of oil recovery. The drainage of oil under gravity forces is a potentially efficient method as it can reduce the remaining oil saturation to below that obtained after waterflooding. This paper describes a series of experiments of gas invasion under gravity-dominated conditions with special attention to the effects of wettability and water saturation on three-phase flow. The experiments were performed in bead-pack models by spontaneous gas invasion at both low and high water saturations with a spreading oil. Different oil recovery rates were observed depending on the wettability of the beads and initial water saturation. At irreducible water saturation, the process appeared to be less efficient for the oil-wet conditions, while similar oil recoveries are observed for both oil-wet and water-wet media at residual oil saturation. Different recovery rates occur with different fluid morphology, which depend on the matrix wettability and the balance between gravity, viscous and capillary forces. The results have been analysed using dimensionless groups. The Bond (N_B) and capillary numbers (N_C) were modified to include the 3-phase effects of gas, oil and water. However, for these cases the Bond and capillary numbers alone were insufficient to fully describe the dynamics of oil recovery by gravity drainage. Therefore, a new dimensionless group combining the effects of gravity and viscous forces to capillary forces was defined as: N=N_B+A(μ_d/μ_g)N_C, where A is a scaling factor (in all our experiments A=−17225) and (μ_d/μ_g) is the viscosity ratio between the displaced and displacing phase. A linear relationship was found between this new group and the total recovery for all the scenarios tested. The slope was approximately 40 for three cases, i.e., water-wet case at irreducible water saturation, and water-wet and oil-wet cases at residual oil saturation. The oil-wet case at irreducible water saturation has a larger slope, probably due to the blocking effect of water. These experimental results may be used as a benchmark to test theoretical models of three-phase flow under gravity dominated conditions. The new dimensionless group should improve the understanding of the pore scale mechanisms so that these processes can be included in the development of network models and in the processes of upscaling laboratory results.     

阿尔奇公式数值分析及其意义

根据欧姆定律及微积分原理,推导出几种理想情况下的Archie(阿尔奇)公式,模拟分析了胶结指数以及饱和度指数的影响因素.模拟结果表明,亲油储层饱和度指数高于亲水储层,亲油储层饱和度指数相对稳定,而亲水储层饱和度指数受饱和度变化的影响较大,建立了两者的数学关系式.储层水淹程度对Archie公式的影响很大,在水淹层测井解释时须给予重视.     

低渗透油田注水效果分析

对于注水开发,如何注好水,实现油田的稳油控水成为关键。通过对低渗透油区贝301区块注水开发效果的分析,总结出适合该类油田注水开发的措施,为实现低渗透油田稳油控水提供一定的借鉴。     

大港油田埕海二区Z29X1断块油藏注水开发试验评价

大港油田埕海二区Z29X1断块油藏是白云质灰岩复杂断块油藏,为适应提高采收率的需要,注采井网必须精细化研究和管理。在明确研究区注水开发试验目的的基础上,通过地质研究将埕海二区整体进行重新划分。通过对井数及井型进行调整,达到已有注水方案优化的目的。从注入量及产能评价两方面对Z29X1断块油藏注水效果进行了分析,结果表明,井网重新优化组合能有效地控制含水率、改善水驱开发效果。     

Beneficial effects of wettability altering surfactants in oil-wet fractured reservoirs

In fractured reservoirs, an effective matrix-fracture mass transfer is required for oil recovery. Surfactants have long been considered for oil recovery enhancement, mainly in terms of their ability to reduce oil–water interfacial tension. These surfactants are effective when the fractured formations are water-wet, where capillary imbibition of surfactants from the fracture into the matrix contributes to oil recovery. However, another beneficial aspect of surfactants, namely their ability to alter wettability, remains to be explored and exploited. Surfactants capable of altering wettability can be especially beneficial in oil-wet fractured formations, where the surfactant in the fracture diffuses into the matrix and alters the wettability, enabling imbibition of even more surfactant into the matrix. This sequential process of initial diffusion followed by imbibition continues well into the matrix yielding significant enhancements in oil recovery.In order to test this hypothesis of sequential diffusion–imbibition phenomenon, Dual-Drop Dual-Crystal (DDDC) contact angle experiments have been conducted using fractured Yates dolomite reservoir fluids, two types of surfactants (nonionic and anionic) and dolomite rock substrates. A new experimental procedure was developed in which crude oil equilibrated with reservoir brine has been exposed to surfactant to simulate the matrix-fracture interactions in fractured reservoirs. This procedure enables the measurements of dynamic contact angles and oil–water interfacial tensions, in addition to providing the visual observations of the dynamic behavior of crude oil trapped in the rock matrix as it encounters the diffusing surfactant from the fractures. Both the measurements and visual observations indicate wettability alterations of the matrix surface from oil-wet to less oil-wet or intermediate wet by the surfactants. Thus this study is of practical importance to oil-wet fractured formations where surfactant-induced wettability alterations can result in significant oil recovery enhancements. In addition, this study has also identified the need to include contact angle term in the dimensionless Bond number formulations for better quantitative interpretation of rock–fluids interactions.     

裂缝性致密油藏注水吞吐转不稳定水驱开发模拟

为解决裂缝性致密油藏经多轮次吞吐后,产量降低过快的问题,以天然裂缝较为发育的某致密油藏M区块为例,综合考虑基质、天然裂缝和压裂裂缝的物性和压力差异,开展了数值模拟研究,分析了裂缝尖端应力场和裂缝扩展特征.在此基础上,对比分析了注水吞吐、不稳定水驱的开发效果.结果表明,地层压力随注水时间延长逐渐升高,当地层压力高于裂缝开...     

温度对亲水岩心束缚水饱和度的影响

相对渗透率是描述油藏多孔介质中多相流动的重要参数,而束缚水饱和度是影响、控制油水相对渗透率曲线的一个关键因素。通常,相对渗透率是在室温下测定的,高温相对渗透率实验用的岩心偏向于亲油。针对轮南油田油藏温度高的特点,分别应用静态实验和动态实验研究了温度升高对亲水岩心束缚水饱和度的影响,及其对相对渗透率曲线特征的影响。室内实验结果表明,亲水岩心的束缚水饱和度随温度上升而下降,其相对渗透率曲线向左移;亲油岩心的束缚水饱和度随温度升高而增大。     

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注水时移地震监测作为一种提高原油采收率的方法正逐渐被国内外许多大的油气田所关注，但提高油气采收率的效果好坏与用来实施监控油气藏变化的技术有着密切关系，好的方法更能够有利于采收率的提高。在油气藏注水开发过程中，储层流体的分布会发生变化，从而引起储层地震反射波速度、密度以及波阻抗的变化，但这些变化一般很小，只会在地震资料上引起很小的异常，特别当地震资料存在噪声干扰时，利用常规油气藏监测方法实施监测时就变得非常困难。针对这种情况，文章引进了具有抗干扰能力的描述混沌的非线性参数，通过对地震数据提取Lyapunov指数属性来研究油气藏注水后储层物性变化的特征。理论模型研究表明，Lyapunov指数属性具有较强的抗干扰能力，能够较好地反映储层注水后流体的变化情况，在信噪比大于2.5的情况下，可以很好地利用它来预测储层注水后的注水分布范围和注水部位的注水强弱情况。该研究成果有利于时移地震监测技术在实际中的应用。