The Research On Tight Formation Flow Law Of Supercritical CO₂ Injection

In recent years,due to the characteristics of low permeability and tight reservoir physical properties,a lot of carbon dioxide flooding is carried out to enhance oil recovery.Carbon dioxide is easy to reach supercritical state in the reservoir,while in this state,carbon dioxide has zero surface tension,easy to diffusion in porous material.The distribution of supercritical area is the focus of attention.However,due to the contact of crude oil and CO₂,hydrocarbon component in crude oil was extracted,and the critical properties and parameters of CO₂ were changed.Therefore,it is of great significance to study the law of the change of carbon dioxide in the low permeability and tight reservoir.In this paper,we first use the PVTi module to study the properties of CO₂ in the vicinity of the critical point,and study the change of the critical parameters and the critical properties of CO₂ with different light components.By using the numerical simulation experiment,the change law of the mixture of CO₂ and crude oil in the static and dynamic state is studied,and the variation characteristics of the critical parameters are analyzed.Then combined with the development process of gaseous components changes,forming a supercritical region judgment method.The displacement variation of the critical region under the condition of one dimensional long core on the basis of this,at the same time for the five spot pattern and inverted nine spot pattern two modes of variation analysis of the critical region.The reservoir numerical simulation method,combined the CQ oilfield Chang7 reservoir characteristics,based on fluid high pressure physical experiment data and the reservoir fluid phase state characteristic fitting,reservoir numerical simulation model is established,study on the law of the change of supercritical region in the development of the typical well group.To study the law of the change of the supercritical region,provide the basis for the study of the percolation characteristics of supercritical CO₂ in reservoir,at the same time can take different development countermeasures based on the critical region,has a certain guiding significance to the study of reservoir development of CO₂ injection.