弱凝胶-表面活性剂复合调驱技术应用基础研究

【作者】 杜玉洪；

【导师】 赵金洲；

【作者基本信息】 西南石油学院 ， 油气田开发工程， 2005， 博士

【摘要】 目前,弱凝胶调驱技术已经成为注水开发油田后期稳油控水的主要技术之一。由于技术本身的原因以及短期效果与长期效益之间的矛盾,使得目前普遍采用小规模、多轮次重复调驱的做法。然而,油田的生产实践表明,这种做法存在随着作业轮次的增加增油效果逐渐递减的现象。因此一方面研究人员对多轮次调驱效果逐次递减机理进行研究以提高多轮次调驱工艺水平;另一方面,重新对弱凝胶调驱规模和轮次进行系统的研究显得尤为重要;同时寻找以更大程度的提高注水油田开发后期采收率为目的的稳油控水新技术就显得迫在眉睫。本文提出的弱凝胶复合调驱技术,就是将弱凝胶调驱技术与化学驱油技术结合起来的一门新兴的技术,即弱凝胶处理后采用聚合物驱、表面活性剂驱、复合驱提高原油采收率。这项研究无论是对于弱凝胶处理后的油田进一步提高采收率还是对于未进行弱凝胶处理的油田更有效的提高采收率都是有着重要的现实意义。 本文首先通过物理模拟实验研究了弱凝胶多轮次重复调驱,得出多轮次调驱逐次效果递减规律,同时分析增油效果递减机理。研究结果认为:多轮次重复注入弱凝胶体系对层间非均质性、层内非均质性能起到良好的调整作用,能够使后续水作用于低渗透层等开发程度不够的油层,能够有效的提高采收率。但是多轮次调驱明显的存在增油效果逐次递减的现象,分析的结果认为原因归结于以下几点:采用单一调驱剂时每轮调剖的受效面部分重叠、由于每轮的调剖需要不同注入等量调驱剂存在着调剖效果随径向距离增加而减弱的现象、封堵时机引起调剖效果逐次递减、注入工艺引起调剖效果逐次递减和堵剂部分失效引起调剖效果逐次递减等。因此,为了缓解多轮次调驱效果逐次递减,应建立适宜近井地带、过渡地带及远井地带的多轮次调剖堵剂系列;针对调剖剂作用随径向距离增加而递减机理,多轮次调剖时堵剂用量应适当递增,以保证堵剂在放置的位置上有足够的厚度;针对封堵时机引起调剖效果逐次递减机理,应通过数模研究及考虑经济效益综合优化确定每一轮调剖的封堵时机;为了减少注入工艺对多轮次调剖效果的影响,每一轮调剖前应研究调剖井层的启动压力,优化调剖注入压力。 本文的另一个研究重点是弱凝胶复合调驱体系的研制、技术的可行性和提高采收率机理以及弱凝胶表面活性剂复合调驱工艺研究。 本文采用了一种新型的聚合物——疏水缔合聚合物,研制出性能良好的弱凝胶复合调驱体系,完全能满足常规(<80℃)弱凝胶复合调驱的要求。同时,针对在弱凝胶配方研究方面存在的温度使用范围较窄(30～90℃)的问题,本文研制出两种耐温(90～120℃)耐盐调驱体系,完全能够满足高温高盐油藏的弱凝胶复合调驱需要。 弱凝胶复合调驱技术不是弱凝胶调驱和化学驱油的简单加和,它涉及两项技术之间的协同作用,同时调驱剂和驱油剂之间也存在相互作用,这两种作用的结果决定这项技术的可行性及驱替方式等问题。研究的结果表明:弱凝胶处理后,采用聚合物驱、表面更多还原

【Abstract】 So far, the technology on weak gel for profile modification and oil displacement has become one of the main technologies to stabilize oil-output and control water-cut at the latter exploitation of oil field by water injection. For technical reasons and conflicts between short-term effects and long-term beneficial results, multi-cycle weak gel treatments with small scale are adopting in oilfields. However, generous practices show it exists that with the cycles of treatment increasing, the results of EOR gradually decrease. Therefore, for one thing, the mechanism of this phenomenon is being studied in order to improve the technology on multicycle weak gel. For another, it’s time to take a fresh look at scale and cycles of treatment. Besides, it is urgent to search for new technologies in order to further enhance oil recovery. This article demonstrates a new technology combining weak gel and chemical flooding, namely weak-gel in-depth water-diverting and chemical flooding combination technology. That is adopting polymer flooding, surfactant flooding or combination flooding after weak gel treatment. It is a significant study on this technology to further enhance oil recovery for the oilfields by, weak gel treatment. It is also important to more efficiently enhance oil recovery for ones without gel treatment.In this article, physical models are employed to study multi-cycle weak gel treatments. The result shows that it really exists that with the cycles of treatment increasing, the results of EOR gradually decrease. The reasons are following. Firstly, the influence areas of every cycle are partly overlapping. Secondly, with the radial distance increasing, the result of profile modification by equal amount of gel injection becomes worse. Thirdly, the opportunity of injection is another important reason. Lastly, unfitting injection crafts cause worse effects. So, in. order to ease this problem, the following measures can be employed, namely adopting a series of agents, increasing the amounts of treatments with radial distance increasing, optimizing the opportunity and craft of injection.The research on the development of agents, the feasibility of this technology, the mechanism of EOR and the craft of weak-gel in-depth water-diverting and surfactant flooding combination technology is another main emphasis of this article.In this paper, a new kind of polymer, namely hydrophobic associating polymer, is adopted in the study on the development of agents. The formulation of weak gel used this polymer can suit the general need when the temperature of reservoirs is bellow 80 degree. It is well known that common weak gel can not endure high temperature (90-120□) . So, two formulations are developed in this paper in order to satisfy the need of high temperature and salinity reservoirs.The weak-gel in-depth water-diverting and chemical flooding combination technology is not the one that simply puts the technique on weak gel and chemical flooding together. It involves the cooperation of the two techniques and the compatibleness of the two kinds of agents. And the two actions determine the feasibility of the technology and ways of injection. The result of our research shows that the application of polymer flooding, surfactant flooding or polymer-surfactant combination flooding after weak gel treatment can further enhance oil recovery. In addition to weak gel enhancing sweep efficiency and chemicals improving oil displacement efficiency, the two techniques have a good cooperation and thus the oil recovery is enhanced. In-depth water diverting by weak gel results in the following chemicals entering into low permeability layer in which remaining oils enrich.The research on the compatibleness of weak gel and surfactants shows that unformed weak gel and surfactants have a disagreeable interaction. However, pre-formed weak gel and surfactants have a good compatibleness. So, the direct contact of unformed weak gel and surfactants must be avoided.In this paper, take Huabei oilfield for instance, the adaptability of weak-gel in-depth water-diverting and surfactant flooding combination technology on this oilfield is estimated. To look on the physical property and fluid property of the reservoir, the gel can selectively enter into the stratums. With the formulations of weak gel with good temperature and salinity tolerance, the suitable craft and the proper opportunity of injection, weak-gel in-depth water-diverting and surfactant flooding combination technology has an excellent adaptability in Huabei oilfield.更多还原