Study On Productivity Evaluation And Parameters Optimization Of Multi-Branch Horizontal Well

As a high efficiency production method, the technique of multi-branch horizontal well is widely used in low permeability reservoir, heavy oil reservoir, shallow layer reservoir and multi-layer reservoir, because it can significantly improve the productivity of sigle well, inhibit coning and enhance oil recovery. Studying on productivity evaluation and parameters optimization of multi-branch horizontal well is the front subject of this technique. Therefore, Studying on productivity evaluation and parameters optimization of multi-branch horizontal well is important for enhancing oil recovery and integral exploitation benefit of oilfields.On the basis of the related research result at home and abroad, focusing on the key scientific and technical problems which existed in the coupling model of multi-branch horizontal well reservoir seepage and wellbore flow, sensitivity parameter analysis of multi-branch horizontal well, comprehensive and systematic study was done in this thesis, and four aspects of the work was accomplished as follows:(1) Based on the equivalent radium model,horizontal wellbore mass variable flow model and completion skin factor model, the coupling model of multi-branch horizontal well reservoir seepage and wellbore flow is presented, which provides the theoretical basis for sensitivity parameter analysis and parameters optimization design of multi-branch horizontal well.(2) According to the generalized concept of skin factor, on basis of intergral expression of well completion skin factor, the well completion skin factor models of open hole, perforation and slotted screen completion are improved, and the effect of completion parameters on skin factor are studied.(3) Based on the coupling model of multi-branch horizontal well reservoir seepage and wellbore flow, the NPV economic foecast model is established, and the effect of sesitivity parameters of multi-branch horizontal well on the productivity of multi-branch horiozntal well and NPV economic net present value is studied, which provides scientific theoretical basis of parameters optimization designing. (4) Focusing on the completion parameters optimization design problem of the target wellbore section in heterogeneous reservoir, based on coupling model of multi-branch horizontal well reservoir seepage and wellbore flow and well completion skin facor model, the method of the completion parameters sectionalized optimization method of target section wellbore of horizontal well in heterogeneous reservoir is established.From this research, the coupling model of multi-branch horizontal well reservoir seepage and wellbore flow is established. The average error of the result of this model and the numerical simulation is less than 3%. The theoretical basis of the branch parameter optimization and completion parameters optimization is provided by this model. The problem of branch parameter optimization and target well seciton completion parameters optimization design is solved. Meanwhile, a lot of regularity knowledge is got from the research which can provide the technical basis of the completion optimization studying of multi-branch horizontal well.