摘要
井壁失稳一直是困扰石油钻井的重大技术难题,泥页岩水化是造成井壁失稳的最重要因素之一,作为最易吸水和泥页岩主要组分的蒙脱石是引起井壁失稳的根本性因素。利用分子模拟的方法,建立了有机胺类抑制剂与钠蒙脱石反应的分子结构模型,研究了甲酰胺和尿素等小分子有机胺类抑制剂对蒙脱石水化的抑制作用机理。胺类有机小分子抑制蒙脱石水化的能力与分子结构及官能团有关,甲酰胺和尿素均可与层间水分子及蒙脱石表面的氧原子形成氢键,抑制层间钠离子的水化,限制层间水分子及钠离子的自扩散。甲酰胺和尿素分子在不同浓度时对钠蒙脱石体系的密度和力学性能影响不同,但有相同的变化规律,即存在一临界浓度,低于此浓度时,胺类分子的加入可增大蒙脱石的密度,提高体系的力学性能,而高于此浓度时,体系密度减小,力学性能变差。甲酰胺和尿素都是在低浓度时能更好地发挥抑制作用,提高钠蒙脱石的稳定性,综合各参数对比分析,甲酰胺比尿素的整体作用效果好。
Wellbore instability has always been the major difficulty in the process of well drilling,and mud shale hydration is one of the most important factors leading to wellbore instability.Montmorillonite,as the composition with the highest water absorption and the main component in mud shale,is the radical factor of wellbore instability.In this paper,the molecular structure model for the reaction between organic amine inhibitors and Na-montmorillonite was established by means of molecular simulation to study the inhibition mechanisms of small-molecule organic amine inhibitors(e.g.formamide and urea)to montmorillonite hydration.It is shown that the inhibition capacity of small-molecule organic amine mainly depends on its molecular structure and functional group.Formamide and urea can form hydrogen bond with the interlayer hydrone and the oxygen on the surface of montmorillonite to inhibit the hydration of interlayer sodion and limit the self-diffusion of interlayer hydrone and sodion.When the concentrations of formamide and urea change,their effects on the density and mechanical performance of Na-montmorillonite are different,but they follow the same change laws.There is a certain critical concentration,below which the addition of amine can increase the density of montmorillonite,increasing the mechanical performance of this system,and vice versa.And at low concentration,they both can present good inhibition and increase the stability of montmorillonite.Based on the parameter analysis and comparison,formamide is,on the whole more effective than urea.
作者
黄小娟
徐加放
丁廷稷
李小迪
李力文
HUANG Xiaojuan;XU Jiafang;DING Tingji;LI Xiaodi;LI Liwen(School of Energy Resources, China University of Geosciences,Beijing 100083, China;School of Petroleum Engineering, China Petrole University, Qingdao 266580, Shandong, China;National Engineering Laboratory for Subsea Equipment Testing and Detection Technology, Qingdao 266580, Shandong, China;School of Petroleum Engineering, China Petroleum University, Karamay 834000, Xinjiang, China)
出处
《石油钻采工艺》
CAS
CSCD
北大核心
2017年第4期442-448,共7页
Oil Drilling & Production Technology
基金
国家重点基础研究发展计划973项目"海洋深水油气安全高效钻完井基础研究"(编号:2015CB251200)
油气重大专项"大型油气田及煤层气开发"(编号:2016ZX05044003-001)
关键词
蒙脱石
分子动力学模拟
水化膨胀
页岩抑制剂
甲酰胺
尿素
montmorillonite
molecular dynamics simulation
hydrate expansion
shale inhibitor
formamide
urea
