Study On Productivity Evaluation And Optimal Design For Horizontal Wells In Bottom Water Reservoir

Horizontal well technology,used in the development of bottom water reservoirs,could increase contact area with oil reservoir,and control water conning.The main well completion techniques for horizontal include barefoot well completion technique,slotted screen well completion technique,perforation completion technique and so on.And on this basis,partial completion,variable density perforation completion and other completion methods have been put forward to further ease bottom water cresting.By accurately finding out the water production interval of oil wells and then adopting plugging strategy,or properly adjusting the bottom water inflow profile,these techniques can effectively prolong the life of the well.In this paper,in order to optimizing the parameters of different completion techniques,production evaluation and moving principles of bottom have been analysed,which can be provide reliable and theoretical basis for field development project designing in the actual production.Firstly,analyzing flowing discipline of the area near wellbore,a coupling model about reservoir seepage and pressure drop in horizontal well has been built.Considering the fluid flow from reservoir to horizontal wellbore and the perforation oillet,this model is effective to finish the production evaluation of perforated completed and open hole completed horizontal well.And this model with certain boundary conditions can be solved by iterative method.Using the finished programs,many parameters,such as flow rate and wellbore pressure have been calculated.And then the pressure distribution in the reservoir can also been figured out.Secondly,on the base of coupling model,production sensitivity analyses have been finished.The influence of some completion factors,such as well placement,horizontal interval length,perforation density and horizontal well segmented mode have been analyzed and the preliminary optimization of these parameters has been finished.Finally,considering the effects of bottom water breakthrough to wells' life,a bottom water cresting model have been established by use of the coupling model.In this model,the Water flooding process in the vertical direction has been viewed as piston mode.This model can be used to calculate bottom water breakthrough time,predict dynamic variation rule of water cresting and analyze the influence of different parameters to water cresting.Combined with the outcome of preliminary optimization,take cumulative free water production objective function,a more comprehensive optimization has been proposed.The research results of this paper can be used to evaluate the production condition of horizontal well with selective open hole completion or variable density perforation completion.Also,it can be well used to provide guidance to optimization of associated completion parameters.