基于改性氧化石墨烯作为低渗透油藏注水开发纳米减阻剂研究

发布时间：2018-02-28 10:18

本文关键词： 改性氧化石墨烯低渗透油藏纳米减阻剂水驱降压增注　出处：《西南石油大学》2015年博士论文　论文类型：学位论文

【摘要】：低渗透油藏注水开发过程中普遍存在注入压力高、注入能力差的问题,降压增注是该类油田生产的重要工作内容。研发高效的降压增注化学剂是油田化学领域的研究重点之一,本文拟研制一种基于疏水改性氧化石墨烯作为纳米减阻剂来实现低渗透油藏注水开发过程的减阻、降压与增注。论文取得以下成果：(1)对合成氧化石墨烯的传统Hummers法进行了改进：在中温反应阶段结束之后,取消98℃条件下的高温反应,让反应继续在35℃条件下进行,使整个反应的环境更加安全与稳定。采用的改进Hummers法能成功合成单层或者少层的氧化石墨烯,其厚度约为1.1 nm。(2)氧化石墨烯的横向尺寸随pH值的变化规律明显,可以通过调节氧化石墨烯水溶液的pH值来调控氧化石墨烯片层的横向尺寸,进而达到氧化石墨烯横向尺寸可控可选操作的目的。(3)通过建立模型,计算得到烷基胺为氧化石墨烯的最佳疏水改性剂,其反应条件温和,生成产物结构稳定。不同碳链长度的烷基胺与氧化石墨烯发生反应时,随着烷基胺碳链长度的增加,反应越容易进行,改性氧化石墨烯的结构越稳定,并且烷基胺上的胺基优先与氧化石墨烯边缘的羧基反应。(4)在模拟计算的基础之上,选用五种不同碳链长度的烷基胺对氧化石墨烯进行疏水改性,长链烷基均成功地接枝到氧化石墨烯之上,并且反应中伴随着一部分氧化石墨烯表面的含氧官能团的还原。五种碳链长度的纳米减阻剂均能使亲水性岩心表面润湿性发生反转,由强亲水变为强疏水,随着接枝碳链长度的增加,疏水性增强。(5) GO-HDA与GO-ODA两种纳米减阻剂能有效地降低低渗透岩心注水压力,后续水驱压力分别降低了15.32%与45.55%,此时岩心水相渗透率分别是之前的1.18与1.84倍。其中纳米减阻剂GO-ODA的最佳使用参数为：质量浓度20 mg/L～50 mg/L;注入段塞量1 PV-2 PV；与地层吸附时间48 h。温度对GO-ODA在岩心表面的吸附影响较小,并且GO-ODA耐水流冲刷能力较强,后续水驱累计注入量达到200 PV时,岩心渗透率降幅不超过10%。(6)水分子在低渗透砂岩油藏表面的吸附为较强的化学吸附,而水分子在纳米减阻剂GO-ODA-1中酰胺基的N原子附近吸附为弱的化学吸附,在GO-ODA-1碳平面上和长链烷基上的吸附为弱的物理吸附。纳米减阻剂GO-ODA-1在低渗透砂岩油藏岩石与黏土矿物表面的吸附均为强的化学吸附,容易自发进行,并且在岩石表面倾向于平行方向的吸附。纳米减阻剂GO-ODA-1与GO-ODA-1之问的吸附是不稳定的,不容易自发进行,纳米减阻剂分子之间不易于相互聚集而产生堆积堵塞地层,理想状态下在地层岩石与黏士矿物表面倾向于形成单层或者少层吸附,尽量减小对地层的堵塞负作用。(7)基于实验研究与理论计算结果,疏水改性氧化石墨烯作为低渗透油藏注水开发纳米减阻剂的减阻机理为：1)纳米减阻剂M-GO与砂岩油藏表面的水化层发生竞争吸附,形成了M-GO片层强力吸附层；2)纳米减阻剂M-GO在油藏岩石微孔道的吸附及其强疏水性,使得孔壁形成了具有强疏水特性的表面,进而对水流产生了纳米滑移效应；3)纳米减阻剂M-GO在黏土矿物表面吸附所形成的纳米疏水层具有隔水防膨作用。
[Abstract]:Universal high injection pressure waterflooding in low permeability reservoirs, injectivity problems, increasing injection is an important work in the production of oil. The research of effective decompression and augmented injection of chemical agents is one of the key research field in chemistry field, this paper developed a based on hydrophobically modified graphene oxide as nano the drag reduction agent to achieve drag reduction of waterflooding in low permeability reservoir, pressure and increasing injection. The results are as following: (1) the traditional Hummers method for the synthesis of graphene oxide has been improved: after the end of the temperature in the reaction stage, the elimination of high temperature reaction under 98 DEG C, allow the reaction to continue in under the condition of 35 DEG C, the reaction of the environment more security and stability. Using the improved Hummers method can successfully synthesized graphene oxide single or few layer, its thickness is about 1.1 nm. (2) lateral size of the graphene oxide with pH The value changes significantly, can value to control the transverse dimension of graphene oxide layers of graphene oxide by adjusting the aqueous solution of pH, and then reach the graphene oxide lateral dimension controllable optional operation. (3) through the establishment of the model, calculating the best hydrophobic alkyl amine oxide obtained graphene modifier the mild reaction conditions, product structure and stability. Different length of carbon chain alkyl amine and graphene oxide reaction, with the increase of carbon chain length of alkyl amine, reaction more easily, the structure of modified graphene oxide is more stable, and the reaction of carboxyl alkyl amine amine preferentially with graphene oxide edge. (4) on the basis of simulation, the hydrophobic modification of graphene oxide by alkyl amine with five different carbon chain length, long alkyl chains were successfully grafted onto graphene oxide, and the reaction is accompanied by A part of the graphene oxide surface oxygen reduction. Five kinds of nano carbon chain length of drag reduction agent can make the hydrophilic core wettability of reversed, from strong hydrophilic to hydrophobic graft, along with the increase of carbon chain length, and increase the hydrophobicity. (5) GO-HDA and GO-ODA two nm drag reducing agent can effectively reduce the pressure of water injection in low permeability cores, subsequent water flooding pressure were decreased by 15.32% and 45.55%, the core permeability is respectively 1.18 and 1.84 times before use. The best parameters including nano friction reducing agent for GO-ODA concentration of 20 mg/L ~ 50 mg/L; 1 PV-2 PV injection slug with the formation; adsorption time 48 H. temperature on the adsorption of GO-ODA on the surface of the core is small, and the GO-ODA water scour ability, cumulative injection volume reached 200 PV after water flooding, permeability decline is not more than 10%. (6) of water in low permeability The surface of sandstone reservoir is strong chemical adsorption, adsorption of water molecules and N atoms near the amide reduction resistance agent in GO-ODA-1 nm for weak chemisorption, adsorption on GO-ODA-1 carbon plane and long alkyl chain on the physisorption. Nano DRA adsorption of GO-ODA-1 on the permeability of rock and the clay mineral surface and low permeability are strong chemical adsorption, easy spontaneous, and adsorption on rock surface tend to be parallel to the direction of the adsorption of nano GO-ODA-1 and GO-ODA-1 reduction. Resist asking is not stable, not easy to spontaneous, nano reducing resistance agent between molecular aggregation and accumulation is not easy to produce plugging ideally, in the rock and clay mineral surfaces tend to form single or few layer adsorption, to minimize the negative effect on the plug formation. (7) results of experimental study and theory based on the hydrophobic modification of oxygen Graphene nano as waterflooding in low permeability reservoir reducing resistance mechanism of drag reducing agent: 1) nano water reducing agent M-GO layer resistance and sandstone reservoir surface of competitive adsorption, forming a M-GO film layer of strong adsorption layer; 2) nano dra M-GO adsorption on the reservoir rock micro and the strong hydrophobic, the wall formed surface has strong hydrophobic properties, and produce nano slip effect on flow; 3) nano nano anti friction agent M-GO hydrophobic layer formed on the surface of the adsorption of clay minerals have water resisting anti swelling effect.

【学位授予单位】：西南石油大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TE357.6;TQ127.11

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