【作者】 梁晓飞；

【导师】 张寒琦；

【作者基本信息】 吉林大学 ， 高分子化学与物理， 2004， 硕士

【摘要】 聚合物溶液注入油层后，由于聚合物溶液的增粘性，增加了驱替相的粘度，并且聚合物在油层中存在吸附和捕集，增加了渗流阻力，降低了水相渗透率，改善了油水流度比，调整了注入剖面而扩大了波及体积；另一方面，由于聚合物溶液的粘弹性的作用，进一步改善了驱油效果。从而提高了原油的采收率。大庆油田是陆相沉积的大型砂岩油田，油层埋藏深度为1000m左右，油层温度为45℃左右，原始地层水矿化度只有7000mg/L，注入清水矿化度只有400—1000mg/L，采出水矿化度在4000mg/L左右，油层渗透率变异系数在0.5—0.8之间。研究资料表明：这样的自然条件非常适宜聚合物驱油。因而大庆油田采用聚合物驱油与国内外其它一些油田相比具有得天独厚的优越条件。大庆油田自1972年小井距注降试验以来，技术不断完善，目前已实现了聚合物驱工业化推广。在聚合物驱油过程中，聚合物溶液的粘度和粘弹性对提高驱油效率起到了至关重要的作用。聚合物驱油的主要机理是改善油水流度比，扩大波及体积，从而提高原油采收率。聚合物粘弹性越好，扩大波及体积和提高驱油效率的作用越明显。目前所用高水解度聚合物水解度范围为30-50%，随着水解度的升高，羧基基团总量的增加，聚合物溶液粘度增加，为了降低注入成本、节约用量，对高水解度聚合物的稳定性、粘度状况、使用条件、驱油效果进行实验。为保证聚驱效果，聚驱过程中一般采用低矿化度清水配制聚合物溶液。随着聚合物驱工业化的推广，油田消耗清水量越来越多，同时也造成污水由于过剩而大量外排。直接导致了水资源的浪费和严重的污染环境。为了解决这一矛盾，使油田污水得以循环利用，喇嘛甸油田开展了将采出污水用于高水解度聚合物驱油的科研攻关。室内研究表明：油田污水中的微生物及还原性物质是影响聚合物溶液粘度的主要因素。虽然油田污水的矿化度较高（4000mg/L左右），但其配制的聚合物溶液仍能保持较高的粘度。同时，油田污水配制的聚合物溶液具有良好的油层配伍性，在模拟油层条件下，该聚合物溶液抗降解能力强；通过大量的试验分析，确定了曝氧法是处理油田污水中微生物及还原性物质的经济合理的方法，开辟了油田污水处理的新途径；通过清、污水体系聚合物溶液粘弹性和驱油性能的研究分析，并结合目前聚合物配注工艺流程，最终确定了清水配制超高分子抗盐聚合物溶液，曝氧污水稀释的注入方法。该方法可将注聚用水量的五分之四替换成污水。经过喇嘛甸油田北西块5#、6#注聚站的现场试验，取得了明显的驱油效果。高水解度聚合物相对普通聚合物具有较高的粘度和良好的稳定性。采用40%水解度聚合物与普通聚合物进行混配注入或小段塞交替注入，在保证相同驱油效果条件下，可节约聚合物干粉10%。更多还原

【Abstract】 In the process of displacement of oil by polymer solution, the viscosity and viscoelasticity of polymer solution are vital to displacement efficiency. Low TDS fresh water is generally used to prepare polymer solution to ensure polymer displacement effect. The consumption of fresh water in oil field has increased dramatically as the extension of polymer- displacement industrialization. Meanwhile extremely large amount of produced water has to be drained away, directly resulting in water resource waste and serious environmental pollution. To resolve this problem, LaMaDian Oil Field embarks on the study of using produced water in polymer–displacement process to realize recycle application of produced water.Polymer solution’s viscosity and viscoelasticity are vital in the process of displacement. The main mechanism is to enhance oil recovery by improving water oil mobility ratio and expanding volumetric sweep. The more conspicuous effects could be obtained with a better polymer’s viscoelastisity. The hydrolysis range of high-hydrolysis-polymer available is 30-50%. As the hydrolysis degree rising, the total amount of carboxyl group is increasing and the viscosity is getting much higher as well. In order to lower injection cost, a series of experiments in which test high-hydrolysis-polymer solution’s stability, viscosity, using conditions and displacement effects are conducted.Lab tests show: microbes and reducing substances in produced water are major factors to influence polymer solution’s viscosity. Although the TDS of produced water is relatively high (4000mg /L or so), the polymer solution mixed with it can still maintain a higher viscosity. At the same time, this kind of polymer solution has a desirable property to match the reservoir, and demonstrate a better ability to maintain its viscosity in simulative reservoir; a lot of tests prove that the method of exposure-to-oxygen is a economical and logical way to treat microbes and reducing substances existing in produced water; combining studies of viscoelasticity and displacement ability of polymer solution preparing in fresh water and produced water respectively with the latest mix and injection process, an injection method is determined finally that preparing super- high molecule weight polymer solution in fresh water and diluting it with produced water after exposure-to–oxygen treatment. Four fifth fresh water could be replaced with produced water by using this way. Good results have been achieved in field experiments conducted in 5# and 6# injection station, locating in west northern block of LaMaDian Oil Field. Comparing to ordinary polymer solution, high-hydrolysis-polymer solution has relatively higher viscosity and desirable stability. It <WP=72>could achieve the same displacement effects when reducing polymer powder consumption by 10% by means of using high-hydrolysis-polymer with a hydrolysis degree of 40% to mix with ordinary polymer or injecting small volumes of the two sorts of polymers alternately.更多还原