一种流度调控剂的合成及其在孤东油藏的适应性研究

Synthesis of a mobility regulating agent and research of its adaptability in Gudong reservoir

关键词:  非均质高含水油藏  流度调控剂  缔合聚合物  油藏适应性

Key words:  heterogeneous and high water-cut reservoir  mobility regulating agent  associative polymer  reservoir adaptability

摘要:

目的 针对胜利油田孤东油藏现场深部调驱段塞试验效果不理想、油藏适应性差的问题,开发具有良好油藏适应性的高效流度调控剂。方法 以丙烯酰胺和十六烷基烯丙基二溴化四甲基乙二铵(CDAD)为共聚单体,通过水溶液自由基聚合法合成了一种流度调控剂,采用FTIR和¹H-MNR确认了调控剂分子结构,结合黏度、动态光散射、Waring剪切、岩心流动等测试系统地研究了流度调控剂的油藏适应性。结果 在优化确定的最佳反应条件(单体总质量分数为25%、氧化还原型复合低温引发剂(DW-A+DW-B)质量浓度为80 mg/L、pH值为8、尿素质量分数为0.5%)下合成的流度调控剂HAWSP-1具有良好的油藏适应性,当质量浓度为2 000 mg/L时,黏度可达238.3 mPa·s,高速剪切后黏度保留率大于83%,当质量浓度为400 mg/L时,主要粒径分布在2.30~7.50 μm,在渗透率为700×10-3 μm²的岩心上建立较高阻力系数与残余阻力系数的同时,呈现出较低的动态滞留量(256.62 μg/g),在平均渗透率为2 500×10-3 μm²的3层非均质岩心驱油实验中,可提高采收率20.25%。结论 引入疏水单体,通过对分子结构的设计与合成条件的优化,可明显提升流度调控剂的溶液性能,还可在保证注入性的前提下呈现较好的非均质调驱性能,在非均质高含水油藏深部调驱中具有重要的参考和推广意义。 

Abstract:

Objective In view of the problems of poor pilot effect and poor reservoir adaptability of the existing mobility regulating slugs in Gudong oil reservoir of Shengli oilfield, a high-efficient mobility regulating agent with good reservoir adaptability was developed. Methods The mobility regulating agent(HAWSP-1)was synthesized by aqueous free radical copolymerization of acrylamide and cetyl allyl dibromo tetramethyl ethylene diamonium (CDAD), and then the molecular structure of HAWSP-1 was further confirmed by FTIR and ¹H-NMR. Moreover, the reservoir adaptability of HAWSP-1 was systematically studied by the tests involving viscosity, dynamic light scatter, Waring shear, core flow, and so on. Results HAWSP-1, prepared under the determined optimal reaction conditions (total monomer mass of 25 wt%, redox composite low-temperature initiator (DW-A+DW-B) dosage of 80 mg/L, pH value of 8 and urea dosage of 0.5 wt%), exhibits good reservoir adaptability. HAWSP-1 can achieve viscosity of 238.3 mPa·s and higher viscosity retention ratio (more than 83%) after high-speed shearing at the concentration of 2 000 mg/L, as well as own a size distribution ranging from 2.3 to 7.5 μm at the concentration of 400 mg/L. More importantly, HAWSP-1 can establish a higher resistance (or residual resistance) factor and present a lower dynamic retention amount of 256.62 μg/g at a water permeability of 700×10-3 μm², which was accompanied with a higher enhanced oil recovery by 20.25% in three-layer heterogeneous core with an average permeability of 2 500×10-3 μm². Conclusion sThe introduction of hydrophobic monomers, molecular structure design and optimization of synthesis conditions not only can significantly improve the solution performance of the mobility regulating agent, but also can present better performance to profile control and oil displacement under the premise of ensuring injectability, which has important reference and promotion significance in the in-depth profile control and oil displacement for heterogeneous and high water-cut reservoirs.