考虑沥青质沉积的储层压力场数值模拟

油藏开发过程中,随着储层压力的下降和轻质组分的采出,原油中的胶质、沥青质等重质成分逐渐析出并沉积在岩石孔隙表面,造成渗流通道的堵塞,导致开发效果变差。本文根据相平衡理论和修正的Flory-Huggins溶解理论,建立了沥青质组分的最大溶解度模型,结合毛管束模型,推导了沥青质沉积对孔喉半径的影响公式,建立了单井渗流模型,并对模型进行了求解;与常规模型相比,该模型考虑了沥青质沉积造成的绝对渗透率损伤,压力场的波动导致沥青质的析出,而沥青质的析出又会反作用于压力场,影响开发效果。研究结果表明,随着储层压力降低,沥青质的溶解度先减小后增大,在饱和压力处取得最低值,为减少沥青质析出对开发效果的影响,应尽量使地层压力保持在饱和压力附近;沥青质沉积主要发生在生产井附近,随着到生产井距离的增大,沥青质沉积量逐渐减小,对储层渗透率、孔隙度的影响也逐渐变弱;压力场求解结果表明,当考虑沥青质沉积时,生产井附近渗流阻力增大,地层压力衰减加快。     

衰竭开发沥青质析出相态及数值模拟研究

在油田开发过程中,沥青质沉积可导致地层孔隙堵塞,造成油田产量下降,因此开展沥青质沉积规律研究非常必要。本文在室内实验的基础上,研究了沥青质的相态特征,利用气-液-固三相平衡理论绘制了沥青质析出包络线图,得到了沥青质析出的温度和压力范围。根据A油田实际资料,建立了沥青质模拟的数值模拟模型,能够模拟沥青质析出、絮凝、沉淀和伤害四个过程;分析了沥青质析出对地层的伤害,随着沥青质的析出,地层孔隙度和渗透率降低,原油粘度增加;研究了沥青质析出对采出程度的影响,考虑沥青质时,生产10年采出程度下降2.3%,最优井底流压为35MPa。     

基于最小二乘支持向量机的二氧化碳驱油沥青质沉积对储层伤害的动态分析

油田开发过程中注CO2驱替原油常会发生沥青质沉积现象,沥青质沉积由于吸附和桥塞作用会伤害储层,会降低储层的孔渗性。本文利用数值模拟方法研究沥青质沉积过程,及对油田实际生产的影响。首先通过LSSVM机器学习算法拟合了沥青质沉积与气体浓度及压力之间的非线性关系;之后运用渗透率伤害GPT模型来建立砂岩储层沥青质沉积量与渗透率降低率的伤害模板;最后建立了五点井网下的地质模型,模拟相应工作制度下沥青质伤害前后的注入井注入能力、生产井生产能力及剩余油分布状况。模拟结果表明,沥青质沉积主要集中在近井地带,对注入井的注入能力影响较大,同时由于沥青质对储层的伤害会导致渗流阻力的增大影响气水波及效率,从而引起生产井产量的下降及最终采收率的降低。     

高凝油油藏冷伤害机制

考虑高凝油石蜡组分溶解在原油中、分散颗粒悬浮在原油中、沉积在孔隙壁面3种形态,静态沉积、动态沉积、孔喉捕集3种沉积过程,以及地层孔隙度与渗透率的指数关系,建立高凝油油藏冷伤害机制数学模型.实例计算表明:油藏温度场的变化是影响高凝油油藏开发效果的主控因素;注入冷水将导致近井带温度很快降到析蜡点以下并逐步向外推进,石蜡颗粒逐渐析出;随着生产的进行,注水井井筒附近区域石蜡析出量和沉积量增加幅度逐渐减小,而在远离注水井的区域则呈现相反趋势;石蜡沉积使产油量大幅度下降,应采取措施避免地层冷伤害的出现.     

高凝油藏中蜡沉积对开发效果的影响

针对高凝油注水开发中蜡析出造成孔隙堵塞、渗透率下降这一问题,推导蜡沉积量与孔隙度、渗透率变化关系,建立水驱油藏渗流场与蜡沉积的耦合模型,对比地表水常温及适当升温(25、35、45、55、65℃)注入时,含水饱和度分布及孔隙度、渗透率降低情况。结果表明:注入冷水导致近井地带温度降至析蜡点以下,蜡晶颗粒大量析出,地层采出水(45℃,不加热)回注时,注水1 a后水井附近30 m温度受到影响,平均累积沉积量约占孔隙体积的4%;随着温度降低,含水饱和度前缘跃变程度减弱,渗透率与初始渗透率比值由93%降到72%;地层冷伤害随时间延长加剧,但增加速率逐渐减小,并逐渐向油层深部推进。     

衰竭开发沥青质析出相态及数值模拟

在油田开发过程中,沥青质沉积可导致地层孔隙堵塞,造成油田产量下降,因此开展沥青质沉积规律研究非常必要。本文在室内实验的基础上,研究了沥青质的相态特征,利用气-液-固三相平衡理论绘制了沥青质析出包络线图,得到了沥青质析出的温度和压力范围。根据F油藏实际资料,建立了沥青质数值模拟模型,能够模拟沥青质析出、絮凝、沉淀和伤害4个过程;分析了沥青质析出对地层的伤害,研究了沥青质析出对采出程度的影响,随着沥青质的析出,地层孔隙度和渗透率降低,原油黏度增加,生产10年采出程度下降2.3%。通过优化井底流压,可为防止沥青层沉积提供指导,研究成果显示F油藏最优井底流压为35.5MPa。     

高含硫气藏元素硫沉积及其对储层伤害模型研究

根据元素硫的溶解沉积机理和物质平衡原理,利用高速非达西渗流理论,建立了元素硫沉积模型及受元素硫沉积影响的地层孔隙度、渗透率随生产时间的变化关系.研究表明:元素硫的沉积主要发生在近井地带1.5m以内,离井筒越近,沉积越严重,孔隙度和渗透率下降越大,对储层伤害越大;气井产量越大,硫沉积越严重,孔隙度和渗透率下降越大,合理产量应控制在(15~20)×104m3/d;高含硫气体的渗流表现出强烈的流固耦合特性.     

生产参数对沥青质井筒析出影响规律研究

针对油田沥青质井筒沉积问题,开展了生产参数对沥青质井筒析出影响规律研究,研究中采用了压差法,高温高压条件下测定温度、油气比、流速等对沥青质析出压力与再溶解的临界压力的变化规律。研究结果表明,沥青质析出压力（p_onset）与温度成反比,而沥青质再溶解的临界压力（p_red）与温度成正比;温度一定,沥青质析出压力（p_onset）随着油气比增大而增大,即原油中溶解气体量大,沥青质沉积的趋势增大;油气比和温度一定时,流速变化对沥青质的析出压力和再溶解压力几乎没有影响。     

原油沥青质的沉积条件及其控制

原油温度、压力和组分的改变均会引起沥青质发生絮凝和沉积,造成储层损害。沥青质沉积热力学预测模型可以更直观、方便地确定沥青质的沉积条件。建立了一种沥青质沉积条件的预测模型,该模型将沥青质沉积相视为固相,按液固相平衡来处理沥青质的沉积问题,根据井筒流体组成和地层性质等资料,估算原油沥青质开始沉积的压力,并提出相应的井下热力学控制条件。利用该模型预测了渤海SZ36-1油田具有代表性的3口油井的原油沥青质发生沉积的初始压力,结果表明,随着压力不断下降,原油中的沥青质在沉积初始压力处开始发生沉积,且该压力比地层温度下的原油饱和压力高出2~4 MPa,这为预防油井发生沥青质沉积具体措施的制订提供了理论依据。     

致密砂岩油藏CO2驱替沥青质沉积及储层伤害特征

CO2注入原油后产生的沥青质沉积会引发储层伤害并严重影响致密油藏开发效果.以鄂尔多斯盆地HQ油田B153区块为例,通过开展不同注气压力下的岩心驱替在线核磁扫描实验,在排除矿物沉积的影响下,分别从CO2驱替前后沥青质沉积量、渗透率伤害率和孔喉堵塞率三个方面研究沥青质在岩心中的沉积特征,评价不同注气压力下沥青质沉积对储层的伤害程度.结果表明,随着CO2注入压力上升,CO2溶解和抽提萃取能力增强,CO2突破时间延迟,原油采收率大幅度提高.但当注气压力高于最小混相压力(MMP)时,原油采收率增加幅度减小.沥青质沉淀量和渗透率伤害率随注入压力的升高而不断增加,但当驱替方式由近混相(20 MPa)向混相(24 MPa)过渡时,沥青质沉淀量和渗透率伤害率增加幅度最大,且小孔喉(0.68×10-3μm相似文献   

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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