Research On The Technical Strategy For The Development Of Deep Heavy Oil Enhanced Cold Production

The widespread distribution of heavy oil and the large amount of reserves make its efficient mining method more and more important.As for the low permeability deep heavy oil reservoir,the commonly used mining methods conclude steam flooding,steam stimulation and other thermal production method,these thermal recovery methods have better effect in the early stage of development,but with the process of mining,there are some problems about thermal production can be found,such as high cost of exploitation,gas pipeline easily aging,serious steam channeling and so on,so it is essential to study the cool production for heavy oil.Based on the characteristics of mid-deep heavy oil reservoir with edge and bottom water,combined with the actual geological conditions,this article firstly make the comparison between some common cool production methods and thermal production methods,and a more suitable cold recovery method is filtrated.According to the study on the changed phase of CO₂ in borehole and numerical simulation to verify the adaptability of cold mining method and the viscosity reduction mechanism of CO₂ is briefly analyzed.On the basis of the vertical well and horizontal well productivity formulas which consider the start-up pressure gradient,using equivalent flow resistance method to establish the mixed well pattern of vertical-horizontal wells productivity formula.It obtain technical well pattern density from these productivity formulas.Meanwhile,it utilizes numerical simulation to validate the optimal well spacing pattern to cool production in the square hydrocarbon reservoir with edge and bottom water.Furthermore,on the basis of the optimum well pattern,the parameters of horizontal wells are optimized from three aspects of position,length and direction.In addition,utilizing numerical simulation to optimizes the injection-production parameters,such as the volume ratio between CO₂and viscosity reducer,liquid volume and so on,and an example of its application is given.In order to exploit heavy oil in efficient way,the results reveal that CO₂ combining with viscosity reducer to aid the water drive is a better producing way,and it could get best effect for injecting CO₂ in bottom of reservoir.We could achieve satisfied outcomes when apply the vertical wells-horizontal wells irregular well pattern,place wells in side of formation to control edge and bottom water invasion.The application results of a fault block in Dongxin Oilfield show that the development effect is improved obviously,which is instructive for same kind of reservoir’s efficient development.