Study On Water Flooding Development Performance Of Horizontal Wells In Common Heavy Oil Reservoir

In the development of common heavy oil reservoirs,horizontal wells have great advantages over vertical wells.Under the same conditions,the reservoir contact area of horizontal well is larger and the production pressure difference required is smaller,which can reasonably use the energy of reservoir,prolong the water free oil recovery period,and improve the oil production and recovery.Through literature research,it is found that the current research on the development of horizontal wells in heavy oil reservoirs at home and abroad mainly includes the development technology policy and theory of horizontal wells,numerical simulation of horizontal wells,production calculation of horizontal wells,indoor physical simulation experiment,water cut rising law of horizontal wells,and research on Influencing Factors of water drive effect of horizontal wells.The quantitative study of water drive performance of horizontal wells under different parameter combinations,such as formation permeability,crude oil viscosity and injection production well pattern,is rarely involved in the previous work.In this paper,through indoor two-dimensional physical simulation experiment,based on the experiment,using reservoir engineering dynamic analysis method,combined with reservoir numerical simulation,the water drive recovery factor and its influence law under different permeability,crude oil viscosity,injection production well pattern and other parameter combinations are studied.The main achievements are as follows(1)The results of physical simulation experiments show that when the well pattern and viscosity are fixed,with the increase of well spacing,the slower the flow velocity at the outlet,the longer the time to reach 90% water cut,and the lower the comprehensive water cut,due to the decrease of pressure gradient between injection and production wells,the more reserves controlled between injection and production wells,the more oil production,the higher the recovery degree and waterless recovery.(2)Under the condition of constant viscosity,when the well spacing is small,the water drive recovery degree of inclined injection production well pattern is larger;When the well spacing exceeds a certain range,the recovery degree of injection production well pattern is greater.(3)When the reservoir enters the high water cut stage,its production decline conforms to the law of harmonic decline.When the viscosity exceeds 300 m Pa·s,the water flooding recovery is less than 30%.(4)Through variance analysis,it can be seen that permeability,crude oil viscosity and well spacing have a great influence on final recovery.The order of significance of these three factors is: crude oil viscosity?well spacing?permeability.In the case of isotropic permeability,with the increase of permeability,the average pressure of reservoir decreases gradually,while the average water saturation,comprehensive water cut and recovery increase gradually.With the increase of crude oil viscosity,the average reservoir pressure increases,the comprehensive water cut first decreases and then increases,while the average reservoir water saturation and recovery factor decrease.Through the research on water drive performance of horizontal wells in heavy oil reservoir,this paper quantitatively analyzes the change law of water cut and recovery degree under different parameter combinations,which can provide more solid basic data and reference for water drive development of horizontal wells in common heavy oil oilfield in the future.