Supercritical CO (sub) 2 Mouth Flow Characteristics And Stratified Gas Injection Well Simulation

Separate layer CO2injection is an important method to solve the contradictions among layers in the process of reservoir development, ensure effectively injecting CO2into layers with different permeability, keep the energy of permeable formation, maintain long-term stable and high yields, and improve recovery. CO2phase change is found in the wellbore, CO2is supercritical around the injection choke., There are differences in practice compared with conventional single-phase water injection Well chart, characteristic curves of single-phase gas in the ground and choke flow curves of gas-liquid. So those theories cannot be directly applied to choke flow of CO2, it seriously hinders the further popularization and application of separation CO2injection technology. Therefore, this paper combines the physical simulation with’ theoretical research, has done a deep reseach of choke flow characteristics of supercritical CO2and gas injector system analysis model, the main work as following:(1) Choke flow experiment of CO2was carried out, having simulated the critical flow and subcritical flow, tested the flow rate of supercritical CO2in different choke size (0.8～1.2mm), upstream temperature of choke (333-363K)/pressure (16～20MPa), established theory model and multiple parameters model of flow rate, and predicted more supercritical CO2choke flow characteristics using multiple parameters model, providing a important key technology for separation CO2injection technology;(2) Based on the literature data, this paper has evaluated and optimized the physical parameters and thermodynamic parameter model of deviation factor, viscosity, density et al; established the predicting coupled model of wellbore pressure/temperature gradient. Combining of the formation inspiratory model, this paper has put forward the corresponding numerical method, providing the theory support for separate CO2injection;(3) This paper has developed a simulation software of separate CO2injection which can calculate the wellbore pressure/temperature profile of the CO2injection Wells and the size of th chokes, analysizing the single parameter using the node system method, providing a important key tool for separation CO2injection technology;This paper has taken Well X in Jilin Oilfield as an example for the simulation and analysis. The calculation of wellbore temperature and pressure error are respectively1.16%and3.36%, the calculation of different flow rate in different choke size provides an important theoretical basis and method.