通常二氧化碳气源来自电厂或者天然气处理厂，也有部分来自于二氧化碳气井，

通常二氧化碳气源来自电厂或者天然气处理厂，也有部分来自于二氧化碳气井，这些二氧化碳在处理之前都含有一定的水、杂质气体、固体颗粒等，而杂质的存在会对整个二氧化碳处理流程和设备造成一定的影响甚至破坏，因此，需要建立一整套完善的二 氧化碳地面工程来保证从捕集—增压—干燥到注入的整个过程安全、高效地进行。 <br>二氧化碳的气源地点一般离注入地点较远，因此需要一种经济的输送方式使其到达 注入点，船舶运输不适应于内陆、汽车罐车运输方式只适用于小规模且短距离条件，因 此管道输送方式成了大规模、长距离输送二氧化碳的首选方式。 <br>管道输送二氧化碳时其状态有气态、液态和超临界状态三种形式，为了确定最有利的输送状态，从二氧化碳物性角度对其密度、粘度和热容及导热系数等参数随温度和压 力变化情况进行分析，得出管道输送二氧化碳时，最有利的状态为超临界态。进一步对 各个状态的输送距离界限进行了探索，得出输送气态时由于压降较大，其输送的有效距 离仅为37.5km，液态管道由于相态变化的影响，一次加压的有效输送距离为204.4km， 而输送超临界状态的二氧化碳时，由于超临界状态的影响，其维持超临界性的有效距离 为128.1km，若对超临界性要求不高，则可以继续增大输送距离，达到1010km。 <br>氮气和甲烷是二氧化碳气体中的主要杂质，管道输送混合气体时对其性能会产生一 定的影响，通过分析得知：少量的氮气和甲烷的存在对气体和超临界管道的压降和温降 影响可以忽略，但是对液态管道的温降和压降较大，且氮气的影响要大于甲烷的，因此 要尽量避免。 <br>论文最后以大情字井油田二氧化碳输送注入模式进行分析，提出两种优化模式，通过对先后模式和改进方式的能耗和费用进行对比，确定得出，二氧化碳在集气站进行低压超临界增压，输送方式采用低压超临界输送、在注入站进行高压超临界注入的方式最经济。

Usually, carbon dioxide gas sources come from power plants or natural gas processing plants, and some also come from carbon dioxide gas wells. These carbon dioxide gases contain certain amounts of water, impurities, solid particles, etc. before treatment, and the presence of impurities can have a certain impact or even damage on the entire carbon dioxide treatment process and equipment. Therefore, A complete set of comprehensive carbon dioxide ground engineering needs to be established to ensure the safe and efficient operation of the entire process from capture, pressurization, drying to injection.<br>The gas source location of carbon dioxide is generally far from the injection site, so an economic transportation method is needed to reach the injection point. Ship transportation is not suitable for inland transportation, and car tanker transportation is only suitable for small-scale and short distance conditions. Therefore, pipeline transportation has become the preferred method for large-scale and long-distance transportation of carbon dioxide.<br>When transporting carbon dioxide through pipelines, there are three types of states: gaseous, liquid, and supercritical. In order to determine the most favorable transport state, the density, viscosity, heat capacity, and thermal conductivity of carbon dioxide are analyzed from the perspective of its physical properties with temperature and pressure changes. It is found that the most favorable state for transporting carbon dioxide through pipelines is the supercritical state. Further exploration was conducted on the transportation distance limits of various states, and it was found that due to the large pressure drop during the transportation of gaseous states, the effective distance for transportation was only 37.5km. Due to the influence of phase changes, the effective transportation distance for liquid pipelines under one pressurization was 204.4km. However, when transporting supercritical carbon dioxide, the effective distance for maintaining supercritical state was 128.1km due to the influence of supercritical state. If the requirement for supercritical state is not high, You can continue to increase the conveying distance to 1010km.<br>Nitrogen and methane are the main impurities in carbon dioxide gas, and when transporting mixed gases through pipelines, their performance will be affected to a certain extent. Through analysis, it is found that the presence of a small amount of nitrogen and methane can have a negligible impact on the pressure drop and temperature drop of gas and supercritical pipelines, but it has a significant impact on the temperature drop and pressure drop of liquid pipelines, and the impact of nitrogen is greater than that of methane. Therefore, it is necessary to avoid it as much as possible.<br>Finally, the paper analyzes the carbon dioxide transportation and injection mode in the Daqingzijing Oilfield and proposes two optimization modes. By comparing the energy consumption and cost of the sequential mode and the improved mode, it is determined that the low-pressure supercritical pressurization of carbon dioxide in the gas gathering station is the most economical method, with low-pressure supercritical transportation and high-pressure supercritical injection at the injection station.

Usually, carbon dioxide gas comes from power plants or natural gas treatment plants, and some of it comes from carbon dioxide gas wells. Before treatment, these carbon dioxide all contain certain water, impurity gas and solid particles, and the existence of impurities will affect or even destroy the whole carbon dioxide treatment process and equipment. Therefore, it is necessary to establish a complete set of carbon dioxide ground engineering to ensure that the whole process from capture-pressurization-drying to injection is carried out safely and efficiently.<br> The gas source of carbon dioxide is generally far away from the injection point, so an economical transportation mode is needed to make it reach the injection point. Ship transportation is not suitable for inland, and truck tanker transportation mode is only suitable for small-scale and short-distance conditions, because this pipeline transportation mode has become the first choice for large-scale and long-distance transportation of carbon dioxide.<br> When transporting carbon dioxide by pipeline, there are three forms: gaseous state, liquid state and supercritical state. In order to determine the most favorable transportation state, the changes of its density, viscosity, heat capacity and thermal conductivity with temperature and pressure are analyzed from the perspective of carbon dioxide physical properties, and it is concluded that the most favorable state is supercritical state when transporting carbon dioxide by pipeline. Furthermore, the transport distance limit of each state is explored, and it is concluded that the effective transport distance is only 37.5km when transporting gaseous state, and 204.4km when transporting carbon dioxide in supercritical state because of the influence of supercritical state. If the requirement for supercritical state is not high, the transport distance can be further increased to achieve.<br> Nitrogen and methane are the main impurities in carbon dioxide gas, which will have a certain impact on its performance when transporting mixed gas in pipeline. Through analysis, it is known that the influence of a small amount of nitrogen and methane on the pressure drop and temperature drop of gas and supercritical pipeline can be ignored, but the temperature drop and pressure drop of liquid pipeline are larger, and the influence of nitrogen is greater than that of methane, so it should be avoided as far as possible.<br> At last, the paper analyzes the carbon dioxide transportation and injection mode in Daqingzijing Oilfield, and puts forward two optimization modes. By comparing the energy consumption and cost of the sequential mode and the improved mode, it is determined that it is the most economical to carry out low-pressure supercritical pressurization of carbon dioxide at the gas gathering station, and the transportation mode is low-pressure supercritical transportation and high-pressure supercritical injection at the injection station.