CO2驱分层注气井注入系统数学模型及其应用

Mathematical Model and Application of Injection System in Stratified CO2 Flooding

CO2驱分层注气是控制CO2气窜和提高开发效果的有效手段.确定合理的分层注气参数是CO2驱分层注气现场试验的关键环节.本文在CO2驱单管分层注气和同心双管分层工艺的基础上,通过分析注入CO2在地面管道、井筒、气嘴及地层中的流动规律,分别建立了两种注气工艺注入系统的数学模型,利用节点系统分析方法对数学模型进行求解和敏感性分析,能够确定不同注气工艺条件下各层合理的注气压力和注气量.以吉林油田CO2驱注气井为例,结合实际地层参数,确定了各层合理的注气参数,为CO2驱分层注气的现场实施提供理论依据和指导.

Stratified gas injection is an effective method to control the CO2 channeling and improve the development effect in CO2 flooding.The determination of reasonable gas injection parameters is the key step in the field test of CO2 flooding.Based on the single tubing and double concentric tubing stratified gas injection process,considering the CO2 flowing characteristics in the pipeline,wellbore,gas nozzle and formation,the mathematical models of the two stratified gas injection technologies are established.The models are solved with nodal analysis method and sensitivity analysis is carried out.The reasonable injection pressure and injection rate of each layer in both injection technologies can be determined.Taking the CO2 injection wells in Jilin oilfield as an example,the reasonable gas injection parameters of each layer are determined by combining with the actual formation parameters.The study in this paper can provide theoretical basis and guidance for the field application of stratified gas injection in CO2 flooding.