【作者】 曹正权；

【导师】 孔瑛；

【作者基本信息】 中国石油大学 ， 化学工程与技术， 2008， 博士

【摘要】 在油田注水开发过程中,油井出水的危害很多:如消耗驱替能量,减少油层最终采收率,造成管线和设备的腐蚀与结垢,增加脱水站的负荷等等,严重时还会使油井变为无工业价值的报废井,造成极大的资源浪费,因此降低采出液的出水率有其重要的意义。长期以来,国内外堵水、调剖剂的研究与应用受到了广泛的关注。早在20世纪30年代国外就开始探索应用不同的调剖堵水剂,我国化学堵水调剖技术始于20世纪50年代,经过长期的研究试验和发展,已经形成了一系列油田注水开发过程中的治水技术。国内外油田广泛应用的化学调剖堵水剂品种繁多,以阴离子型聚丙烯酰胺类为主的水基凝胶是其中发展最快的一个大类。然而目前采用的聚丙烯酰胺可动凝胶调堵技术仍然存在许多局限性,影响了其应用规模。主要存在以下几方面问题:一是聚丙烯酰胺多为粉剂,分散溶解困难,现场施工不方便;二是成胶时间和成胶强度不易控制,往往近井地带堵调效果好,而难于到达地层深部发挥作用;三是由于地层对聚合物和交联剂的吸附能力不同,加上地层水的稀释,使得交联体系在地层中易发生色谱分离,堵剂利用率低。针对以上问题,本文开展了乳液型聚丙烯酰胺调堵剂研究,旨在开发一种新型的调堵剂,更好地满足油田开发过程中治理“水害”的需要。本文利用乳液型聚丙烯酰胺在水中易分散溶解、有效浓度高的特点,进行了乳液型聚丙烯酰胺调堵剂的研究。通过系统地开展调堵机理、乳液聚合机理、交联机理和堵剂结构设计研究,成功研制了乳液型聚丙烯酰胺-酚醛树脂凝胶调堵剂,首次将反相乳液聚合技术用于注水油田开发过程,解决了聚丙烯酰胺凝胶调剖堵水时交联时间和交联强度难以控制,现场配制不便的难题。该调堵技术是在地面将该调堵剂分散于水中,注入到地层指定位置,在地层温度和转向剂的作用下,聚丙烯酰胺反相乳液转相破乳,聚丙烯酰胺和交联剂发生交联反应形成凝胶。由于在到达指定位置前未转相破乳,聚丙烯酰胺与交联剂的比例不发生改变,交联反应得到有效控制。为了确保堵剂的应用效果,本文在以往注聚开发数学模拟分析模型的基础上,修订建立了乳液型聚丙烯酰胺调堵剂应用效果预测模型,并对现场注入方案进行了优化,较好地指导了现场应用。本文的主要研究内容包括以下三部分:第一,开展了聚丙烯酰胺反相乳液制备工艺技术研究,通过对聚丙烯酰胺反相乳液聚合体系组分及聚合条件进行研究,合成了有效含量高、稳定性好、分子量在640~1050万的聚丙烯酰胺反相乳液。研究结果表明,较低乳化剂量时体系不稳定,乳化剂量太高会造成产物分子量下降,而且造成生产成本上升,乳化剂量宜选用8wt%;随着水相单体浓度的增加,聚合物分子量增大,但是,乳液聚合的温度升高,乳液稳定性变差,因此,水相单体浓度选用45wt%,油水比选择为1:1,适宜的聚合起始温度为10~25℃。第二,开展了交联剂的合成工艺及交联机理研究,利用合成的聚丙烯酰胺反相乳液和交联剂,配制成均相的乳液型调剖堵水剂,并进行了理化性能评价、物模封堵性能实验评价。研究结果表明,聚丙烯酰胺-酚醛树脂交联符合两步交联机理,随着聚合物浓度和交联剂用量的增加,交联强度相应增加;温度在50℃以下时,聚合物交联体系不发生交联或交联程度很低;在体系处于酸性条件下时,酚醛树脂与聚丙烯酰胺的交联程度很低;pH值在中性和弱碱性条件下容易形成性能优良的凝胶;岩芯模拟实验表明乳液型调堵剂成胶性能可控,封堵效果良好。第三,通过数模研究优化了现场试验方案,并在孤岛油田油水井上进行了堵水调剖试验,见到了明显了降水增油效果。经现场应用证明,该调堵剂具有分散溶解方便、成本低、成胶时间和强度易于控制等优点,能够达到地层深部封堵出水通道,实现液流改向、控水增油的目的,在经济上可收到较好的效果,预计投入产出比可达1:3以上,推广应用前景良好。更多还原

【Abstract】 The disadvantages of produced water from oil well during the water injection exploitation in oilfield include consuming the displacement energy, reducing the final percent recovery of oil-bearing sand, the corrosion and fouling of pipes and equipments and increasing the load of dehydration station, etc. The oil well may be changed into worthless abandoned well, which may produce enormous resources waste. Therefore, it is important to reduce the specific yield of produced liquid. It has been widely noticed worldwide about the related research of water block and drive-adjusting reagent. Seventy years have passed since the related technology about various drive-adjusting reagents was investigated. Series of water treatment technologies have been formed through research experiments and development for a long time during the water injection exploitation in oilfield. There are many kinds of chemical water block and drive-adjusting reagents used worldwide, the water base gel polyacrylamide of anion type was developed fast.However, the drive-adjusting technology with gel polyacrylamide present used has many disadvantages, which districted the application scale. Firstly, the polyacrylamide is pulvis. It is difficult to solve it, which make it is inconvenient to field use. Secondly, it is difficult to control the gel form time and gel intensity. Therefore, it is difficult to take effect into the deep stratum. Finally, the crosslinking system tends to separate because of the different sorption performance of stratum to polymer and crosslinking agent, which leads to the decreasing availability of plugging agent. With regard to the above problems, this paper has conducted the research on polyacrylamide inverse emulsion deep drive-adjusting reagent with the aim to develop a new kind of drive-adjusting reagent and satisfy the need of water treatment during the exploitation in oilfield.In this paper, the polyacrylamide emulsion deep drive-adjusting reagent, which has the advantages of easy dissolution and high effective concentration, was investigated. By the system research on the plugging mechanism, emulsion polymerization mechanism, crosslinking mechanism and structure design of plugging agent, the polyacrylamide emulsion and phenolics drive-adjusting reagent was prepared successfully. This paper took use of the inverse emulsion polymerization technology into the water injection exploitation in oilfield firstly and solved the difficult problem of uneasy control of gel form time and gel intensity as well as inconvenient formulation in field. The drive-adjusting reagent and inversion reagent are dispersed into water on ground, and then they are injected to drive-adjusting block by water well. After some time, the inversion phase deemulsification of polyacrylamide inverse emulsion will occur at the circumstances of temperature and existed water in stratum. Gel will be formed during the crosslinking reaction between polyacrylamide and crosslinking agent. The inversion phase deemulsification does not occur until the drive-adjusting reagent, which viscosity is low at this time, reaches the required stratum. To assure the application effect of plugging agent, this paper established the predictive model for application effect of polyacrylamide emulsion drive-adjusting reagent. The optimization of injection scheme in field also guided the field application.The investigation content includes the following three parts. First, the preparation process of polyacrylamide inverse emulsion was developed. The polyacrylamide inverse emulsion was synthesized by the investigation of polymerization system and polymerization conditions. The polyacrylamide inverse emulsion with the molecular weight of 6400-10500 thousand has the following advantages: high effective content, excellent stability. The experiment results showed that the optimum content of emulsifying agent was 8wt%. The system was unstable when the content of emulsifying agent was low. The molecular weight of product was low when the content of emulsifying agent was high. The molecular weight of product increased with the increasing monomer concentration. However, the temperature of emulsion polymerization increased and the stability of emulsion weakened with the increasing monomer concentration. Therefore, the optimum monomer concentration was 45wt%, the oil-water ratio was 1:1 and the optimum beginning temperature of polymerization was 10~25℃. Second, the synthesis process and crosslinking mechanism of crosslinker were developed. The homogeneous inverse emulsion drive-adjusting reagent was synthesized by polyacrylamide and crosslinker. And the physical chemical property evaluation and plugging performance evaluation were conducted. The results showed that the crosslinking was in deference to two-step crosslinking mechanism. The crosslinking intensity increased with the increasing polymer concentration and content of crosslinker. When the temperature was lower than 50℃, the crosslinking degree was at low level. The simulation experiments for well core showed that the drive-adjusting reagent can be controlled easily and has excellent plugging performance. Finally, the test scheme in field was optimized by the mathematical simulation investigation. The water plugging and drive-adjusting test was conducted in the water wells in Gugao Oilfield. The water decrease and oil increase effect was obvious. The field application results showed that the drive-adjusting reagent can be resolved easily. And the drive-adjusting reagent has low cost. The gel form time and gel intensity can be controlled easily. The product can reach the deep plugging stratum, change the flow direction, control the water and increase oil. The economic effect was obvious and the input output ratio can reach 1:3. The application prospect of the drive-adjusting reagent was excellent.更多还原