【作者】 闫文华；

【导师】 康万利；

【作者基本信息】 大庆石油学院 ， 油气田开发工程， 2008， 博士

【摘要】 本文分析了大庆油田二类油层的地质特点,针对目前大庆油田二类油层聚合物驱矿场应用普遍存在的问题,进行了以下几方面的研究。1.针对大庆油田二类油层聚合物驱实施分质分压注入技术,对流经分子量调节器的不同相对分子质量的剪切聚合物溶液以及未剪切的相同相对分子质量的聚合物溶液的黏弹性进行了实验研究,研究结果表明:剪切聚合物溶液与未剪切聚合物溶液的黏性符合幂律模式,稠度系数随相对分子质量的增大而增大,幂律指数随相对分子质量的增大而减小;剪切聚合物溶液的第一法向应力差随剪切速率的增大变化不大,低相对分子质量聚合物溶液的第一法向应力差较低,基本不变。测定了剪切、未剪切两种聚合物溶液的残余阻力系数,实验结果表明:剪切聚合物的残余阻力系数小于相同相对分子质量的未剪切聚合物溶液的残余阻力系数;随着聚合物相对分子质量的增大,残余阻力系数增大。2.开展了不同渗透率岩心与聚合物溶液的相对分子质量的适应性研究,将经过分子量调节器剪切的相对分子质量分别是600×10⁴、800×10⁴、1200×10⁴和1600×10⁴左右的聚合物溶液以及未剪切的相同相对分子质量的聚合物溶液在均质岩心上进行驱油实验,结果表明:无论相对分子质量高低,剪切聚合物溶液的聚驱采出程度均小于相同相对分子质量的未剪切聚合物溶液的聚驱采出程度;高相对分子质量的剪切聚合物溶液的聚驱采出程度大于未经剪切低相对分子质量聚合物溶液的聚驱采出程度;无论相对分子质量高低,剪切聚合物溶液的聚驱最高注入压力小于未剪切的相同相对分子质量的聚合物溶液的聚驱最高注入压力。采取三管并联的驱油方式,模拟聚合物驱油笼统注入和分质注入工艺,实验结果表明:多层同采时,分质注入的采出程度高于笼统注入方式,分质注入的最高注入压力低于笼统注入方式;对于渗透率是300×10^-3μm²～200×10^-3μm²的岩心,驱油聚合物应选择剪切后中等相对分子质量的聚合物溶液,渗透率100×10^-3μm²左右的岩心,驱油聚合物应选剪切后低相对分子质量聚合物溶液。3.应用五点法井网的产量公式推导了聚合物驱注入压力公式,分析了影响聚驱注入压力的因素;以此开展了降低二类油层聚驱注入压力的方法研究,结果表明:注入表面活性剂、减小井距、降低注入速度、压裂、周期注聚等措施,在二类油层降低聚驱注入压力是可行的;表面活性剂与聚合物交替注入方式既可以降低注入压力又可以提高采出程度;周期注聚可以降低聚合物驱的注入压力,周期数越多,效果越好;周期注聚方式可以提高非均质岩心的采出程度,对均质岩心采收率影响不大。4.针对二类油层非均质性严重,注聚过程中同一单元内水、聚两驱共存现象进行了研究。以大庆油田北二西西块二类油层注聚开发区为例,采用数值模拟方法研究了水聚同驱情况下,水聚驱不同注入参数组合下的开采特征,研究结果表明:水聚接触区域各类油水井之间主要存在两类连通关系,一区主要连通关系为:“三次加密油井—三次加密水井—聚驱油井—聚驱水井”;二区主要连通关系为:“三次加密水井—三次加密油井—驱油井—聚驱水井”;聚水强度比对一区接触区域的影响较大,对二区接触区域影响较小;当存在水聚同驱时,应采用两口油井封边,水聚区接触区域的连通关系应采用“三次加密水井—三次加密油井—聚驱油井—聚驱水井”;对于一区连通关系,适合在注水强度较大的条件下开采,最佳方案的聚水强度比为聚:水=1:2;对于二区连通关系,适合在注聚强度较大的条件下开采,二区水聚驱接触区域最佳方案的聚水强度比为聚:水=3:1;对于一区的连通关系,当聚水强度比聚:水=1:2时,聚驱区域和水驱区域的合理的地层压力分别为11.7MPa、11.25MPa;对于二区的连通关系,当聚水强度比为聚:水=3:1时,聚驱区域和水驱区域的合理的地层压力分别为10.95MPa、10.42MPa。更多还原

【Abstract】 This article analyzed geologic characteristic of sub-layers reservoir in Daqing Oil Field, and in the view of the prevalent problem of polymer flooding used of sub-layers in Daqing oil field, made some researches as bellow:1.Research on viscoelasticity of polymer solution with various molecular weights sheared by molecular weight regulator and which with same molecular weight （unsheared） was carried out , in the view of the different medium and pressure injected technique of polymer flooding used of sub-layers in Daqing oil field. It concludes that: The viscosity of polymer solution sheared or unsheared fits power law mode, consistency index increase with the increasing of molecular weight; while the power law index decrease with the increasing of molecular weight; the first normal stress different of polymer solution sheared does not change greatly with the increasing of shear rate, the first normal stress different of which with the low molecular weight is lower, nearly with no change. Through testing the residual resistance factor of polymer solution sheared and unsheared, results show that: Polymer solution with the same molecular weight, the residual resistance factor of unsheared is higher than that of which sheared; the residual resistance factor increase with the increasing of the molecular weight.2. Research on adaptiveness of core with different permeability and different molecular weights of polymer solution carried by doing flooding experiment of polymer solution which molecular weight is 600×10⁴,800×10⁴,1200×10⁴ and 1600×10⁴, which are sheared when flow through the molecular weight regulator, as well as which with the same molecular weight but unsheared on the core, the results show that: The recovery rate of polymer flooding unsheared is higher than which sheared with the same molecular weight, no matter the molecular weight is higher or not; the recovery rate of polymer flooding sheared with higher molecular weight is higher than the unsheared but with the lower molecular weight; the maximum injection pressure of polymer flooding unsheared is higher than which sheared with the same molecular weight, no matter the molecular weight is higher or not; when multi-zone produce, recovery rate of different medium injection is higher than commingled injection, and the maximum injection pressure is lower; for the core with the permeability from 200×10^-3μm² to 300×10^-3μm², polymer solution with medium molecular weight which was sheared is best for displacement, but for the core with the permeability 100×10^-3μm²,which with the low molecular weight is the best.3. Fetched the injection pressure formula of polymer flood by using production formular of five-spot flood system,analysed the factors which impact on injection pressure of polymer, and on the basis of it, researched on the methods of decreasing polymer flooding injection pressure of sub-layers reservoir, the results show that: Injecting SAA, decreasing well spacing , dropping injection rate, fracturing bond gravel, injecting polymer periodically and so on are workable for decreasing polymer flooding injection pressure of sub-layers reservoir; injection pressure could be decreased greatly and recovery rate could be also increased by injecting SAA and polymer alternatively; injection pressure could be decreased by injecting polymer periodically, the more period, the better effect, it doesn’t have much effect on homogeneous core while it could improve recovery rate of inhomogeneous core.4. Heterogeneity of the sub-layers is serious, polymer and water flooding exist in the same unit for polymer injection, the coexistence make polymer flooding potential difficult to play. In this paper, take polymer flooding sub-layers of western North Block for example, research recovery feature of water and polymer displacement at the same time with different combination of injection parameters use numerical simulation method. Study results showed that: relation of the various types of oil and water wells statistics in water- polymer contact zone show that there are two mainly types of connection, first zone connection is oil well third infill- water well third infill-oil well polymer flooding-water well polymer flooding, second is water well third infill- oil well third infill-oil well polymer flooding-water well polymer flooding. When coexistence of water and polymer displacement, border should be sealed by two oil wells, connection of water and polymer contact zone is water well third infill- oil well third infill-oil well polymer flooding-water well polymer flooding. For first zone, it should be developed with high water injecting force,the best rate is 1:2 of polymer and water injection force;for second zone,it should be developed with high polymer flooding force,the best rate is 3:1 of polymer and water injection force.For the first zone, when the ratio of force between polymer and water is 1:2,the reasonable pressures of polymer and water zone are 11.7Mpa and 11.25Mpa, and For the second zone, when the ratio of force between polymer and water is 3:1,the reasonable pressures of polymer and water zone are 10.95Mpa and 10.42Mpa.更多还原