论文部分内容阅读
当实施提高采收率(EOR)项目把CO2作为溶剂时,主要有三个寻求CO2注入剂来源的选择。这三个选择是天然CO2沉积物、人为烟道气捕集,或来自EOR项目早期阶段的循环CO2。所有这些来源可能都含有改变注入剂性质的杂质,潜在地影响系统的所有阶段。例如,捕集的烟道气可能含有N2,而采出或循环CO2源可能含有CH4和/或NGL。两者或其中之一可能含有SO2或H2S。这些杂质的每一种都对CO2的热力学和流体流动特征有不同影响,显示出对注入剂的混相能力、密度和黏度及其与地下油气相互作用的有利或有害影响。这些杂质还能够改变压缩能力、腐蚀控制和管道技术要求。本文描述了CO2杂质对EOR项目所有阶段(从CO2捕集到驱替效率预测)的影响。混相能力、密度和黏度以及岩石性质是给定岩石和流体系统驱替效率的主要决定因素。开发出了一个筛选工具以便预测不同原油的EOR动态。该筛选工具的一个关键组成部分是基于溶解度参数的方法,为了获得一个原油范围的混相能力,该方法可以用于筛选含有杂质的CO2注入剂。结合世界作业经验,应用这一技术评价了符合压力、温度和流体组成条件的油藏的EOR潜力。通过准确评价杂质在注入剂中的影响,能够在不增加处理液流来清除所有杂质的费用的情况下,能够找到确保和利用注入剂供给的最佳经济解决办法。通过矿场实例,讨论了混相能力、密度和黏度对CO2混相驱工艺效率的影响。
When implementing EOR projects using CO2 as the solvent, there are three main options for seeking sources of CO2 injectors. These three options are natural CO2 deposits, anthropogenic flue gas capture, or circulating CO2 from the early stages of the EOR project. All of these sources may contain impurities that alter the properties of the implants, potentially affecting all stages of the system. For example, the captured flue gas may contain N2, while the recovered or recycled CO2 source may contain CH4 and / or NGL. Either or both may contain SO2 or H2S. Each of these impurities has a different effect on the thermodynamics and fluid flow characteristics of CO2 and shows a beneficial or detrimental effect on the miscibility, density and viscosity of the implants and their interaction with subsurface hydrocarbons. These impurities can also change the compressibility, corrosion control and pipeline technical requirements. This paper describes the effect of CO2 impurities on all stages of the EOR project, from capture of CO2 to prediction of flooding efficiency. Miscibility, density and viscosity, and rock properties are the major determinants of the displacement efficiency of a given rock and fluid system. A screening tool was developed to predict the EOR dynamics of different crude oils. A key component of the screening tool is a method based on solubility parameters that can be used to screen CO2 implants containing impurities for a crude-phase miscibility. Combined with world operating experience, this technique was used to evaluate the EOR potential of reservoirs that meet pressure, temperature and fluid composition conditions. By accurately assessing the effect of impurities in the injector, the best economical solution to ensure and utilize the injector’s supply can be found without increasing the cost of the process stream to remove all impurities. Through the field examples, the influence of miscibility, density and viscosity on the efficiency of CO2 miscible flooding process was discussed.