Laboratory Experiment And Numerical Simulation Of Gas Assisted Steam Flooding In Block B Of Xinjiang Oilfield

The steam recovery technology of heavy oil is currently one of the main heavy oil thermal recovery technologies.Block B of Xinjiang Oilfield had a good development effect in the early steam flooding process.However,in the later stage of steam flooding,the occurrence of steam channeling and decreased oil displacement efficiency were caused by several problems,so that the heat utilization efficiency and economic benefits of steam flooding had a cliff descent.In order to improve the development effect in the later stage of steam flooding,the laboratory experiments and numerical simulation techniques were carried out.Besides,other researches such as gas-assisted steam flooding mechanism,production well development dynamic analysis in the test area,and optimization of injection-production parameters were also conducted.Firstly,the current development stage and the mechanism of the development mode in the test area were analyzed,the key point of adjustment in the denudation stage could be found,which is the perforations adjustment and gas-assisted steam flooding.Later,the PVT experiments of gas and heavy oil were carried out,so that the dissolution of N₂ and CO₂ gas and the viscosity characteristics of heavy oil were clarified,the mechanism of these two gases can be clearly understood.Besides,the one-dimensional displacement experiments were carried out,and it was found that CO₂ can significantly improve the displacement effect of heavy oil,while the N₂ used as a comparison was not suitable in this Block.Secondly,a dynamic analysis of the development status of the test area in Block B was conducted,and the current problems in the test area were also analyzed.By using OFM,the production data of the test area was statistically summarized and the production wells were divided into five types.Finally,a mechanism model was established through CMG's STARS,and the production injection ratio,steam injection rate,gas-liquid ratio and sub-cool were optimized through numerical simulation,the optimized parameters can bring better production effect to the test area.For problems such as steam channeling,low recovery rate,a later adjustment plan was proposed for the test area through history matching and production dynamic prediction.