L井区进一步加密井网后聚驱可行性分析及开发效果预测

针对A区块L井区聚驱后仍有一定量剩余油密集区存在的问题,研究了该区域聚驱后剩余油分布特征,对进一步加密井网后聚驱挖潜剩余油的可行性进行分析,设计并优选了聚驱开发方案.研究表明,通过进一步加密井网后聚驱的方法来挖潜L井区的剩余油是可行的,优选出最佳聚驱段塞组合方案聚驱阶段采出程度为6.68%,采收率为54.42%,与常规水驱相比,采收率提高了5.02%.     

葡I组油层聚驱后剩余油分布情况及挖潜措施

大庆南五区葡Ⅰ油层组从2005年开始进行聚驱开发.根据大庆油田第二采油厂提供的动、静态数据,采用数值模拟方法,分析了葡Ⅰ油层组聚驱后剩余油分布规律,结果表明:PI组聚驱后剩余油主要集中在P12b、P12c剩余油潜力巨大;聚驱后可以采用调剖、堵水、重复压裂、井网调整等措施进行挖潜.研究结果为葡Ⅰ油层组后续开发提供了指导依据.     

聚合物驱油藏剩余油潜力分析及压裂时机确定

萨尔图油层目前已进入高含水阶段,聚驱后剩余油分布情况及聚驱开发过程中生产井压裂时机的选择是亟待解决的问题.通过数值模拟方法分析了研究区的潜力分布情况,同时针对高含水期聚驱油藏,分别在见效初期、含水低值和含水回升三个阶段进行压裂措施开发效果预测,确定了注聚过程中的压裂最佳时机为含水低值阶段.为高含水期聚驱油藏开发过程中剩余油挖潜措施提供了技术支持,同时对矿场压裂措施的实际应用具有指导意义.     

M区块不同配制水质对聚驱开发效果影响研究

M区块目前应用聚驱三次采油技术来进一步提高原油采收率,研究不同水质配制的聚合物溶液对驱油效果的影响,运用数值模拟方法,在历史拟合的基础上对试验区剩余油分布进行了描述,并设计了4种不同水质条件下的聚合物配制方案,进行聚驱效果影响研究.研究结果表明,在聚合物浓度和注入速度均相同的前提下,清配清稀配制的聚合物溶液驱油效果最好,污配污稀曝氧后驱油效果略好于污配污稀曝氧前,清配污稀驱油效果最差,与水驱相比采收率提高值分别为10.11%、9.04%、8.59%和8.18%.     

A区块三元复合驱参数敏感性分析及合理范围研究

A区块目前应用三元复合驱采油技术来进一步提高原油采收率,不同的物化参数对驱油效果的影响大不相同,不同的参数敏感程度也不同.利用CMG数值模拟软件建立概念模型,对三元复合驱的流变性、油水界面张力、吸附等参数敏感性进行分析,在各组物化参数分析中设计不同的分析方案,分别预测不同方案下三元复合驱的开发效果,提高采收率幅度变化,根据物性相近三元复合驱B区块拟合结果确定参数合理范围.研究结果确定了A区块三元复合驱体系参数的合理设置范围,其中粘度损失率的合理范围为0.4～0.6,油水界面张力应达到10~(-3)数量级,化学剂吸附系数合理范围为0.5～1.5.     

预测水驱油藏中油、水流动问题的快速方法

以最佳正交分解(POD)技术为基础提出了一种快速预测油藏中油、水流动问题的方法.采用POD技术建立了水驱油藏中油、水两相流动的低阶模型.通过油藏数值模拟方法获得二维水驱油藏模型在时间0～500 d内的压力和含水饱和度的100个样本, 并从样本中提取出一组压力和含水饱和度的POD基函数.当注采参数不断变化后,采用已求得的POD基函数结合低阶模型对新的物理场进行预测.研究结果表明:POD方法能够快速、准确地预测出水驱油藏的压力和含水饱和度场,文中算例给出压力和含水饱和度场的预测误差分别不超过1.2%与1.5%,且计算速度比直接进行油藏数值模拟快50倍以上.     

污水中不同含聚浓度对聚合物驱油效果影响研究

M区块应用聚合物驱技术提高采收率.应用数值模拟方法进行历史拟合,在此基础上,针对700万分子量抗盐聚合物和2500万分子量聚合物,分别设计了3种不同含聚浓度聚驱方案,进行污水中不同含聚浓度对聚驱效果影响研究.结果表明,对于700万分子量抗盐聚合物和2500万分子量聚合物单一段塞聚驱方案,两种分子量下均为污水中含聚浓度越大,采收率越高,当含聚浓度为400mg/L时,采收率最高,分别比水驱提高了11.37%和11.03%;且当污水中含聚浓度相同时,700万抗盐聚合物驱油效果好于2500万聚合物.     

三元段塞组合结合数值化方案对微观剩余油研究

微观剩余油赋存状态是设计调整评价油田开发方案的重要依据.利用微观可视驱油实验系统,结合现场段塞组合,开展三元段塞复合驱替模拟实验,并采集不同驱替阶段的图像,同时利用图像识别方法,根据不同类型微观剩余油的数字化几何特征计算出每类微观剩余油的含量及驱油效率,明确段塞组合体系微观剩余油采收效果.实验结果表明,该数值化方法可以区分出不同类型微观剩余油个数及含量,为该类可视化实验奠定良好的分析基础;强碱与弱碱三元段塞组合提高采收率幅度相当;较高的主段塞粘度能奠定一个良好的采收率基础,并且段塞粘度递增的组合提高采收率效果要高于粘度稳定的段塞组合.     

重力泄水辅助蒸汽驱开发中后期油藏动用形态

辽河油田洼59块为巨厚块状砂岩稠油油藏,采用重力泄水辅助蒸汽驱开发目前已至中后期,大排量连续汽驱后,汽腔波及体积已达到最大,继续连续汽驱势必会发生严重汽窜.为明确重力泄水辅助蒸汽驱开发中后期油藏动用形态,确保合理开发稠油油藏,建立了稠油重力泄水辅助蒸汽驱数值模型,理论研究连续汽驱至中后期的压力、含油、含水、含汽饱和度场的分布,直观展示了油藏的动用形态特征.同时,基于油汽比及油藏的热损失综合考虑,提出后续开发的研究重点,应采用重力泄水辅助间歇汽驱,研究其生产过程中油藏的生产参数变化规律,实现对超稠油的高效开发.     

胜利断块油藏细分注水技术界限研究

老油田进入特高含水期后,剩余油分布更加零散,各种地质因素也因长期注水开发而发生了一定的改变.此时稳油控水难度进一步加大,为了进一步挖掘剩余油,控制含水上升速度、减缓产量递减,必须对注水井采取进一步的细分调整.基于水湿油藏注水井注水层段吸水效果,从注入水受力分析入手,运用达西定律推导出了水驱油藏水驱油全过程中的单位体积注入水沿竖直、地层两个方向运移的渗流速度公式,明晰了水驱油藏注水层段不同开发阶段砂岩吸水机理.研究结果表明,水驱油藏细分注水效果与岩石绝对渗透率、水相相对渗透率、注入水黏度、水动力压力梯度、注水井启动压力梯度、含水饱和度、地层倾角、油水密度差等参数有关.结合胜利油田断块油藏地质特征及细分注水工艺要求,制定了一套适合胜利油田不同断块区的细分注水技术政策界限:层段内渗透率变异系数小于0.3,砂岩条带宽度极比小于2.5,且东辛油区断块油藏层段内砂岩厚度小于6m,小层数小于4个;现河油区断块油藏层段内砂岩厚度小于5m,小层数小于5个;临盘油区断块油藏层段内砂岩厚度小于6m,小层数小于6个.矿场试验证实,该细分注水技术政策界限是合理、实用的,其为胜利断块油藏注上水、注够水、注好水,实现多层断块油藏的高效开发提供了技术保障,对类似油藏细分注水技术界限研究具有一定的借鉴意义.     

榆树林油田CO_2吞吐采油目标井优选方法研究

CO_2吞吐是开发低渗透油田的有效方法之一,但进行CO_2吞吐前目标井的优选是关键步骤,它直接关系到CO_2吞吐措施的成败.首先分析了剩余油饱和度、油井含水率、油层厚度、渗透率、孔隙度、井底流压各因素对CO_2吞吐效果的影响,从而建立评价指标,然后利用层次分析方法确定各单因素的合理权重,最后根据模糊综合评判法优选出树11Y68-57和树11Y67-611两口油井适宜CO_2吞吐.优选出的油井具有良好的的油效果,表明该方法是正确可行的,具有一定的推广价值.     

Influence of the polymer degradation on enhanced oil recovery processes

Polymer flooding is one of the most common and technically developed chemical Enhanced Oil Recovery (EOR) processes. Its main function is to increase the carrying phase’s (i.e., water or brine) viscosity in order to mobilize the remaining trapped oil. Many numerical simulators have been developed during the last 30 years considering the influence of the polymer molecules on the viscosity as well as on other physical parameters (e.g., diffusion, adsorption). Nevertheless, there are certain phenomena which were not previously considered, for instance, the interfacial effects of hydrophobically modified polymers. Furthermore, the degradation of the polymer molecules in a harsh environment such as the one found in porous media is well known. This causes a deterioration on the viscosifying properties, diminishing the efficiency of the method. It is important also to consider the effect of the polymer viscoelasticity on the microscopic sweeping efficiency, lowering the residual oil saturation, which has not been properly addressed. A new compositional 2D numerical simulator is presented for polymer flooding in a two-phase, three-component configuration, considering all these physical effects present in porous media and using a fully second-order accurate scheme coupled with total variation diminishing (TVD) functions. Results demonstrated that degradation cannot be considered negligible in any polymer EOR process, since it affected the viscoelastic and viscosifying properties, decreasing the sweeping efficiency at both micro- and macroscopic scales. This simulator will allow setting the desired designing properties for future polymers in relationship with the characteristics of the oil field to be exploited.     

Stable hyperbolic singularities for three-phase flow models in oil reservoir simulation

We study the characteristic speeds of systems of two conservation laws representing three-phase flow in a porous medium with gravity taken into account.Generically hyperbolicity fails on open regions (elliptic regions) where the characteristic speeds assume complex values. The presence of such regions creates difficulties such as multiple solutions which indicate a modeling problem, according to some authors.The hyperbolicity of the models we study depends on the relative permeability functions. It is customary in oil engineering studies to suppose that the water and gas permeabilities depend only on their respective saturation, while the oil relative permeability changes with the gas and water saturations. Such a hypothesis on the oil relative permeability generically leads to elliptic regions.We define a set of three curves that surround elliptic regions of any model. By studying these curves, we indicate a procedure to locate the singularities and prove that for any choice of gravitational and viscosity parameters such regions shrinks to points where the characteristic speeds are real and equal, provided it is assumed that each relative permeability depends on its respective saturation only. Our results, together with a paper of Trangenstein, lead to the conclusion that in order to insure real wave speeds, such an assumption is necessary and sufficient when gravitational effects are considered in three-phase models.Research supported by Brazillian Government grant from CNPq under number 204395/88.7.     

基于储量结构变化的油田开发指标预测与优化数学模型研究

大型油田开发过程中,随着不同类型新储量的不断投入,地质储量结构发生变化,表征油田整体开发技术与经济效果的关键性指标,如产量、可采储量、采收率、储采比、开发成本与操作成本等等也随之改变,其变化规律可用一套数学模型来描述。在开发指标预测基础上,运用多属性决策方法如TOPSIS,可以实现新投产区块组合方案的优选。应用实例表明,本文方法实用、操作性强,可以为油区开发决策提供重要方法与手段。     

识别非均质油田无效注采井和层的数学模型

多层砂岩油藏注水开发后期,在油水井之间形成了储层高渗透通道,导致注入水沿高渗透通道做无效循环,油井产量下降.为改善注入水驱油效果,必须对无效注采井层实施调剖、堵水等措施,而有效识别无效注采井层是解决问题的关键.优选出了识别无效注采油水井和无效注采层位的判定指标,并建立了用于识别无效注采油水井和无效注采层位的模糊综合评判数学模型.     

Mathematical simulation of oil reservoir properties

The study and computational representation of porous media properties are very important for many industries where problems of fluid flow, percolation phenomena and liquid movement and stagnation are involved, for example, in building constructions, ore processing, chemical industries, mining, corrosion sciences, etc. Nevertheless, these kinds of processes present a noneasy behavior to be predicted and mathematical models must include statistical analysis, fractal and/or stochastic procedures to do it. This work shows the characterization of sandstone berea core samples which can be found as a porous media (PM) in natural oil reservoirs, rock formations, etc. and the development of a mathematical algorithm for simulating the anisotropic characteristics of a PM based on a stochastic distribution of some of their most important properties like porosity, permeability, pressure and saturation. Finally a stochastic process is used again to simulated the topography of an oil reservoir.     

冀中坳陷古近系沙河街组三段中亚段岩相古地理

冀中坳陷古近系始新统沙河街组三段中亚段地层全区广泛分布,在钻井、岩心和地震资料等定性和定量资料基础上,运用灰色关联分析方法得到的各单因素关联主因子,优选出5类与沉积相域展布有关的影响因素:地层厚度、粗碎屑岩含量、细碎屑岩含量、红色泥岩含量及暗色泥岩含量.在此基础上,采用单因素分析多因素综合作图法,编制了各层序格架下的岩相古地理图.冀中坳陷古近系沙三中亚段主要发育的沉积相,包括冲积扇、河流、(扇)辫状河三角洲、近岸湖底扇及湖泊.研究结果表明:沙三中亚段主要发育大型冲积扇河流-(扇)辫状河三角洲湖泊沉积体系,并处在冀中坳陷始新统早期的湖盆断陷扩张深陷期沉积这一演化阶段.     

低渗透油藏聚合物强化泡沫调剖剂

为改善某低渗透油田的水驱开发效果,开展了聚合物强化氮气泡沫调剖提高采收率研究.根据该油田的地质油藏条件,建立典型地质概念模型,地质模型能够比较完整地反映地层静态状况和井网条件.对聚合物强化泡沫调剖注采参数进行了优化设计.研究结果表明,聚合物强化氮气泡沫调剖最佳注采参数为:聚合物分子量为800万,聚合物浓度为1000mg/L,最佳泡沫剂浓度为0.25%(质量分数),气液比为1:1.