深水原油采输管界面润滑流动改进机理研究

The exploration of Chinese deepwater petroleum resources has been facing extremely serious challenges of natural condition and geopolitical environment, foundational flow assurance theories of crude production and gathering are crucial for its technical breakthrough. This project intends to study the mechanism of flow improvement by lubrication at fluid-solid interface and its stabilization behavior. Referring to the actual narrow wellbore space and the complex production and gathering pipe routes, an indoor modeling combination pipe system will be established. Basing on numerical simulation and experimental verification, a tubular lubricating fitting for the modeling lubrication system is going to be developed. In this study, taking the super hydrophilicity and high oleophobicity of pipe inner wall as breakthrough point and considering the effects of the pipe material and its surface treatment, pipe combination type, composition and flow rate of lubricant, type and flow rate of crude oil and its simulated oil, deepwater environment temperature, etc., we are going to carrying out the experimental lubrication simulation of deepwater production and gathering pipes, and study their impacts on characteristic parameters like flow pattern, solid phase deposition, pressure drop and so on, thus reveal the mechanism of drag reduction by surface lubrication and of inhibition of solid phase deposition. Accord to the flow patterns and resistance characteristics of lubrication pipe, fluid-solid interface evolution and restart property during the shut-down of the lubrication pipe system, an evaluation method of interfacial lubrication stability is going to be established, and ways of strengthening the stability will be explored. This research can provide insights into the stabilization and flow improvement mechanism of surface lubrication, and lay the theoretical foundation for technical creation of deepwater petroleum production and gathering in China.

我国深水石油资源开发面临的自然条件与地缘政治环境挑战极为严峻，采输（即开采与输送）流动安全保障的相关基础理论对其技术的突破至关重要，本项目旨在探究深水原油采输管流固界面润滑稳定与流动改进机理。针对深水井筒空间狭小与采输管路复杂的特点，建立一套小型的深水采输管路润滑模拟系统，基于流场数值模拟与实验验证，研制适合深水采输管路模拟系统的管式润滑元件；以管内壁超亲水高疏油为切入点，在不同管材及其表面处理、采输管形式、润滑介质组成及流量、原油及其模拟油种类与流量、深水环境温度等实验条件下，实验研究深水原油采输管的润滑及其对流型、固相沉积、压降等特征参数的影响，揭示界面润滑对油流减阻与固相沉积抑制的作用机理；根据润滑管流型与阻力特性、停运过程中润滑层演化与再启动行为，建立界面润滑稳定性的评价方法，探索其强化途径，形成深水原油采输管界面润滑稳定与流动改进理论，为我国深水石油采输技术创新奠定理论基础。

根据项目计划任务书，测试分析含蜡原油、稠油及其模拟油的基本物性；基于低黏液环润滑和油水旋流分离技术，研制出润滑效果良好的管式润滑元件；依托现有环道装置研究了环状流在L型水平弯管和水平直管内的减阻效果、管流稳定性因素、停输再启动特性，并建立对应的压降预测模型；研究了含蜡原油输送过程中抑制固相沉积的影响因素；评价了耐用抗盐水基泡沫体系的性能，研究了影响稠油-泡沫分层流、环状流等流型减阻效果和输油效率的因素，并建立了相应的水动力模型。研究深水原油在采输管中的界面润滑流动改进，有益于探索高黏易凝原油的流动减阻新理论，并且对于油田内易凝高黏油井内原油采输具有降本增效的应用前景。. 研究表明：油水混合液流速为0.54～0.65 m/s时，润滑元件的界面润滑作用良好；L型水平弯管内，油核与管道内径之比为0.8，弯径比为4时，水环稳定性较好；停输时间越长，管道再启动时间就越长，而初始含油率越高，清洗流速越小，均会导致再启动困难程度越大；建立L型水平弯管环状流压降预测模型，水环中加入减阻剂后改变了水环的稳定性，但减阻效果不明显；水平管环状流中，油水性质对界面平均含油率基本没有影响，油密度为996.4 kg/m3，油黏度为943.3 mPa·s，油-水界面张力为22.36 mN/m时，水环的稳定性最好；通过对管材内表面进行改性处理，适度提高管壁粗糙度，以及减小静态接触角，可提高环状流输送稠油的稳定性；含蜡原油输送时，随着沉积时间的增加，蜡沉积量增大，而蜡沉积速率反而降低；研制出AAXH耐油抗盐兼具一定抗温性能的水基泡沫体系，当临界入口泡沫体积分数介于0.24～0.35，油相表观流速高于0.5 m/s时，减阻率高于50%，最大减阻率达70.4%；建立适用于牛顿‒非牛顿或两相均为非牛顿流体的水动力模型，实验值与预测值的相对误差小于20%。