Study On Selection And Evaluation Of Shallow Heavy Oil Reservoir Exploitation Methods

Shallow heavy oil reservoirs has shallow bed,loose cementation,low formation pressure pressure,low reservoir temperature,large crude oil viscosity,low dissolved gas oil ratio,and severe heterogeneity.Conventional methods has poor results.The shallow heavy oil field in Xinjiang explored the field tentatives of thermal recovery and revealed problems such as high local water content,unequal use of profiles,and high deep-seated steam defects.Therefore,starting from the adaptability of five exploitation methods:steam soak,steam flooding,CO₂ Huff-Puff,and CO₂ auxiliary thermal recovery,the appropriate exploitation methods for shallow heavy oil in Xinjiang are evaluated.The main understanding are as follows:?1?At the beginning of exploitation,steam soak has good adaptability,the steam throughput output and the oil steam ratio are large.As the reservoir thickness and the permeability increases,the crude oil viscosity decreases,the rhythm stratum is vertically anisotropic,the effect becomes better.After four rounds,the formation pressure will drop by 1 MPa.It is recommended to transfer steam soak to steam flooding.?2?Steam flooding is suitable for the early and middle development of shallow heavy oil reservoirs.Steam flooding produces a large extent,but the oil steam ratio is relatively low.As the reservoir thickness,the reservoir permeability,and the initial oil saturation increase,the crude oil viscosity decreases,the Lorentz coefficient decreases,the effect becomes better.?3?CO₂ Huff-Puff is only a supplement to shallow heavy oil reservoir exploitation.As the initial oil saturation increases,the average permeability of the reservoir decreases,the rhythm stratum is vertically anisotropic,the effect becomes better.?4?Compared to single steam soak,the effect of CO₂ based steam soak has improved,and the CO₂ oil draining rate is relatively low.The process parameters need to be further designed in the process of field application?5?Compared with single steam flooding,CO₂ based steam flooding has little effect on improving the development of shallow heavy oil reservoirs,but the CO₂ oil draining rate is low.We recommend adding a small amount of CO₂.