油溶性树脂双重交联凝胶型堵剂选择性机理研究

As most oilfields of China turn into the later stage of high water cut, due to the existence of formation heterogenerty，the phonomenon of producing water in oil well become so seriously that oil production falls sharply and water cut increases to a great extent,what is worse,it sometimes may lead to "flooding".Water shutoff has been an important means to increasing and maintaining oil output in the oilfield. However,the success of the water shutoff technology depends on the action and selectivity mechanism of temporary plugging additive and rock pore throat.Aiming at the problems causing by water shutoff,this technology adopts the viewpoint of increasing degree of cross-linking,degrading hydroscopicity of gel and oil soluble resin of compound material toughening and heightening polymer gel to research the microcosmic-mechanism and forms of water shutoff agent.Thereafter flooding mechanism is proposed by studying water output of production well in the later stage of high water cut,this mechanism can be combined with microcosmic-shape of various temporary plugging additive to determine selective water shut off mechanism.Polymer that guided and optimized through secondary crosslinking and blending with oil-soluble resin can synthesize a kind of compound water shutoff material called oil solubel resin-dual crosslinked-gelatinous selective water shutoff agent(ORG).After the demermination of dispensation of ORG, evaluation of prestage and terminal stage performance will play an important role in analysing rheological property,microcosmic gelling mechanism and toughening characteristic,and probing into its selective water shutoff mechanism.To sum up,the above technology will provide new ideas and methods for the research of selective water shutoff agent.

我国大多数油田现在己进入高含水开发后期，由于地层均质性的差异，油井出水现象严重，油量骤减，含水上升，甚至导致"水淹"。因此，油井堵水己经成为油田稳产增产、提高采油效率的重要措施，而堵剂的强度与选择性是指导堵水成功的关键。针对油藏堵水成功率低，选择性差的问题，提出用油溶性树脂双重交联聚合物凝胶的观点进行选择性堵水剂的设计，提高堵剂交联度，增加堵剂的选择性，指导与优化聚合物经过一次交联后，与油溶性树脂共混形成油溶性树脂双重交联凝胶型选择性堵剂(ORG)。在确定ORG的配方后，对其初始阶段及最终阶段的成胶机理进行分析，研究流变性能、微观成胶机理以及增韧特性，探讨选择性堵水机理，为ORG堵剂的应用提供理论支持，为油田的高产稳产提供技术支撑。

通过对油田开发后期油井出水类型、出水机理的调研，油井出水主要有底水錐进和裂缝突进两种类型。优选的ORG堵剂由内网络和外网络组成，ORG堵剂的最佳配方为：1000mg/L超支化聚丙烯酰胺+300mg/L内网络交联剂+800mg/L稳定剂+2000mg/L阳离子聚丙烯酰胺+2000mg/L外网络交联剂+150mg/L增强剂。ORG堵剂成胶后强度大，突破压力大于1.5 MPa/cm，对岩心中水的堵塞率大于90%，对油的堵塞率小于30%，具有堵水率高，堵油率小的特点。对ORG堵剂的力学性能进行研究，主要是通过改变第一层与第二层交联剂的浓度来改变其网络结构中的交联密度来改变其力学强度。.为提高ORG堵剂对高渗透层及裂缝油层的堵塞能力，将ORG堵剂与油溶性树脂复配使用，形成油溶性树脂双重交联凝胶型选择性堵剂，其选择堵水性能更优越。利用自制的选择性堵水模拟装置，评价了不同温度、不同渗透率和相同注入压力下ORG堵剂的选择性堵水能力，随着岩心渗透率的增加，堵水率和堵油率随之增加，低渗透岩心的堵水率和堵油率均较低，但均表现出较好的选择性堵水能力。可视化模拟实验图像可以看出，底水沿高渗条带进入孔隙之中，ORG堵剂主要进入高渗透带，有效控制了底水通道，提高了波及系数。.通过SEM微观分析可知，内网络凝胶交联体系中分子线团聚集度较大，对水的束缚能力较差。外网络凝胶分子线团舒展，网格孔隙较密，形成膜状，对水的束缚能力较强。ORG堵剂在孔隙中以束状连接物的形式存在，并表现出一定的弹性，提高对水的堵塞能力。加入油溶性树脂的ORG堵剂表面微观形貌是一层高分子膜状结构，油溶性树脂镶嵌其中，形貌图中无明显的褶皱。对水驱和ORG堵剂驱替后岩心的CT扫描结果表明，水驱2PV，再注入0.35PV的ORG堵剂，进而水驱至残余油，可以明显降低油层中残余油含量，提高水驱效果和原油采收率。ORG堵剂能使水相渗透率比油相渗透率下降的多，具有一定的选择性，其选择性堵水机理表现为：重力影响、润滑效果、系统压力、油水通道的堵塞、润湿影响、油水通道的分离等因素。主要包括阳离子聚合物的吸附和选择性堵剂凝胶的堵塞，ORG堵剂优先进入含水通道，形成凝胶，降低岩心的水相渗透率。