萨中油田无碱二元复合体系特性及驱油效果研究

发布时间：2019-03-29 20:06

【摘要】：萨中油田主力油层自1996年以来先后有区块投入了聚驱开采,已完成的部分区块取得了提高采收率10-14%的较好效果,累计采出程度达到50%以上。目前萨中聚驱已转入后续水驱的区块中,含水大于98%的井占总井数的43.6%,均已因高含水关井。这部分井的生产,造成产液高、含水高,注采低效循环,增加了生产成本。但在聚驱后油层中仍有50%左右的储量没有采出。目前尚没有聚驱后进一步提高采收率的有效技术。表面活性剂/聚合物二元复合驱油体系相对于三元复合驱来说,配方中去掉了碱,可以最大限度发挥聚合物的粘弹性,减弱由于碱存在引起的腐蚀结垢现象,保持超低界面张力的同时,驱油效果接近三元复合驱,在降低生产成本的同时还可明显提高化学驱油剂的环保性能。因此,为探索聚驱后进一步提高采收率的有效方法,开展无碱二元复合体系特性及驱油效果的研究。本文以大庆油田萨中西区一类储层为研究对象,首先进行了二元复合体系特性研究,包括二元复合体系的流变性、界面张力及注入能力的研究。分析了注入体系、岩心渗透率、聚合物浓度、表面活性剂浓度、聚合物相对分子质量对流变性、界面张力及注入能力的影响。采用静态法研究了二元复合体系中聚合物和表面活性剂的等温吸附曲线,运用天然岩心研究了二元复合体系的动态吸附滞留。通过模拟乳状液,对二元复合体系乳状液的稳定性、粘度以及聚合物和表面活性剂对油水界面流变性质的影响开展了研究。以达西定律和物质平衡法为理论依据,进行相渗曲线实验测定,分析了注入体系、岩心渗透率、聚合物浓度、表面活性剂浓度、聚合物相对分子质量以及岩心润湿性对相对渗透率曲线的影响。利用露头柱状岩心和露头均质长岩心开展驱油实验,研究聚合物平均相对分子质量、质量浓度、表面活性剂浓度和二元复合体系毛管数变化对驱油效率的影响规律。最后对萨中油田无碱二元驱现场区块的开发效果及经济效益进行了总结。研究表明：随聚合物相对分子质量、浓度和矿化度增加,聚合物体系的粘度、第一法向应力差、储能模量和耗能模量增加、界面张力同时增加。随表面活性剂浓度的增加,二元复合体系粘度先有明显降低,之后降低变缓,体系界面张力降低。剪切对聚合物体系流变性及界面张力有影响,各参数值都降低。二元复合体系注入能力实验表明低分子量聚合物与地层的配伍性更高,二元复合体系经模拟剪切作用后注入能力大幅度提升。二元复合体系聚合物的加入,表面活性剂在油砂上的吸附有所减少。二元复合体系随着吸附次数的增加,油水界面张力依次上升。岩心亲油性强、含有残余油和岩心渗透率低都会导致二元复合体系中表面活性剂在岩心中的吸附滞留量增大。二元复合体系乳状液的稳定一方面是由于聚合物和表面活性剂吸附在油／水界面上形成坚固的具有粘弹性特征的吸附膜,能有效地防止液滴之间的相互碰撞而引起的聚结不稳定性;另一方面由于聚合物的存在,在连续相中增加了溶液的粘度,聚合物分子间链链缠绕形成网络结构,束缚液滴的自由运动,使乳状液稳定性增强。渗透率大,亲水性强的岩心采出程度高且二元复合驱比水驱、聚合物驱的效果更好,同时聚合物浓度越高、聚合物相对分子质量越大,二元复合体系驱油效果越好。随着聚合物平均相对分子质量、质量浓度和二元复合体系毛管数的增加,二元复合体系的驱油效率增加,总采收率增加。对于露头均质长岩心,当无碱二元复合体系主段塞中表面活性剂的浓度达到0.2%,体系粘度达到30mPa·s以上时,聚合物驱后无碱二元复合体系驱采收率提高10%OOIP以上,达到理想效果。根据表面活性剂浓度和体系粘度对驱油效果的影响及体系性能综合评价结果,给出了矿场试验的具体方案。矿场试验全区和中心井采收率大幅度提高,见到了明显的增油效果。数值模拟结果表明,扣除钻降影响,试验区全区预汁最终采出程度59.25%,比水驱提高采收率5.9个百分点；中心区预计最终采出程度60.1%,比水驱提高采收率6.3个百分点。按照全区最终提高采收率5.9测算,试验全过程累计产油25.48×104t。全过程总成本23879×104元,平均吨油开采成本937.1元。矿场试验结果表明该技术是成功的,而且取得了较好的经济效益。
[Abstract]:Since 1996, the main oil layer of the main oil layer of the oil field has been put into the production of polymer flooding, and the completed partial block has achieved a better effect of 10-14% of the enhanced oil recovery, and the accumulated oil recovery reaches more than 50%. At present, in the block of the subsequent water drive, the wells with water content of more than 98% account for 43.6% of the total number of wells, all of which have been shut in due to the high water cut. The production of this part of the well results in high production liquid, high water content, low injection and production efficiency, and increased production cost. However, there are still more than 50% of the reserves in the post-drive oil layer. And the effective technology for further improving the recovery ratio is not yet further improved. The surfactant/ polymer binary composite oil displacement system has the advantages that the base is removed in the formula relative to the three-way compound drive, the viscoelasticity of the polymer can be furthest exerted, the corrosion and scaling phenomenon caused by the existence of the alkali is reduced, the ultra-low interface tension is maintained, The oil displacement effect is close to the three-way compound drive, and the environmental protection performance of the chemical oil displacement agent can be obviously improved while the production cost is reduced. Therefore, in order to explore the effective method to improve the recovery ratio after the polymer flooding, the characteristics of the alkali-free binary composite system and the study of the oil displacement effect are carried out. In this paper, a study on the properties of the binary composite system, including the rheological property, the interfacial tension and the injection capacity of the binary composite system, is studied. The effects of injection system, core permeability, polymer concentration, surfactant concentration, relative molecular weight of polymer on rheological property, interfacial tension and injection ability were analyzed. The isothermal adsorption curves of the polymer and the surfactant in the binary composite system were studied by static method. The dynamic adsorption and retention of the binary composite system were studied by using the natural core. The stability, viscosity and the effect of polymer and surfactant on the rheological properties of the oil-water interface were studied by means of the simulation of the emulsion. The effects of injection system, core permeability, polymer concentration, surface active agent concentration, relative molecular weight of polymer and core wettability on the relative permeability curve were analyzed with the theory of Darcy's law and material balance method. The effect of the average relative molecular mass, mass concentration, surfactant concentration and the change of the capillary number of the binary compound system on the oil displacement efficiency was studied by using the outcrop column core and the outcrop homogeneous long core to conduct the oil displacement experiment. Finally, the development effect and economic benefit of the field block of alkali-free binary flooding in the oil field are summarized. The results show that, with the increase of the relative molecular weight, concentration and salinity of the polymer, the viscosity of the polymer system, the first normal stress difference, the energy storage modulus and the energy dissipation modulus are increased, and the interfacial tension is increased at the same time. With the increase of the concentration of the surfactant, the viscosity of the binary composite system is obviously reduced, and then the viscosity of the system is reduced, and the interfacial tension of the system is reduced. The shear has an effect on the rheological property and the interfacial tension of the polymer system, and the parameter values are reduced. The injection capability of the binary composite system shows that the compatibility of the low molecular weight polymer and the formation is higher, and the injection capability of the binary composite system is greatly improved after the simulated shearing action. The addition of the polymer of the binary composite system and the adsorption of the surfactant on the oil sands are reduced. With the increase of the number of adsorption, the oil-water interfacial tension increased in turn. The core lipophilicity is strong, and the low permeability of the residual oil and the core can lead to the increase of the adsorption retention of the surface active agent in the core of the binary compound system. On the one hand, the stability of the emulsion of the binary composite system is to form a strong adsorption film with the viscoelastic property on the oil/ water interface by the adsorption of the polymer and the surfactant, and can effectively prevent the coalescence instability caused by the mutual collision between the liquid drops; On the other hand, due to the existence of the polymer, the viscosity of the solution is increased in the continuous phase, the chain chain of the polymer molecules is wound to form a network structure, and the free movement of the liquid drops is restrained, and the stability of the emulsion is enhanced. As the permeability is large, the core with strong hydrophilicity is high and the binary composite flooding is higher than the water drive, the effect of the polymer flooding is better, and the higher the polymer concentration, the larger the relative molecular weight of the polymer, and the better the oil displacement effect of the binary composite system. With the increase of the average molecular weight of the polymer, the mass concentration and the number of the crude pipe of the binary composite system, the oil displacement efficiency of the binary composite system is increased, and the total recovery ratio is increased. When the concentration of the surface active agent in the main section of the alkali-free binary composite system reaches 0.2% and the viscosity of the system reaches more than 30 mPa.s, the oil recovery ratio of the alkali-free binary composite system after the polymer is driven can be increased by over 10% OOIP when the system viscosity reaches more than 30 mPa.s, and the ideal effect is achieved. Based on the effect of surfactant concentration and system viscosity on the oil displacement effect and the comprehensive evaluation of the system performance, the specific scheme of the mine test is given. The recovery ratio of the whole area and the central well in the mine is greatly improved, and the obvious oil-increasing effect is seen. The results of the numerical simulation show that the final output of the pre-juice in the experimental area is 59.25%, which is 5.9 percentage points higher than that of the water drive. The final recovery of the central zone is 60.1%, which is 6.3 percentage points higher than that of the water drive. According to the final increase of EOR 5.9 in the whole region, the total production of the test is 25.48-104t. The total cost of the whole process is 23879-104 yuan, and the average ton oil production cost is 937.1 yuan. The results of the mine test show that the technology is successful and has a good economic benefit.
【学位授予单位】：东北石油大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TE357.46

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