The Research For Horizontal Wells Productivity Evaluation Method In Low Permeability Reservoirs

Low permeability reservoirs has characteristics of difficult exploitation and low productivity. As a new technology in recent years, horizontal well can effectively improve oil recovery, it has been applied to all kinds of reservoirs successfully. Application of horizontal well to develop low permeability reservoirs, can effectively improve single well productivity and increased recoverable reserves. Based on thorough investigation and relevant theory of horizontal productivity prediction, the horizontal well productivity of low permeability reservoirs is studied in this thesis. First of all, some seepage parameters were analyzed under the condition of low permeability reservoirs, such as flow velocity, pressure, velocity potential. The redefined velocity potential is the function of threshold pressure gradient. Then using the superposition principle, mirror image and conformal transformation, horizontal well stable seepage productivity formula for two different conditions of the threshold pressure gradient and deformation medium were derived and partial productivity influential factors were analyzed. In chapter three, horizontal well unsteady flow productivity formula for two different conditions were derived by Laplace transform method , and the solution of Lapalace palace were derived. In the later two chapters using the research methods of conventional reservoir horizontal well productivity, mult-branch horizontal well productivity influential factors and horizontal well productivity of low permeability reservoirs under the condition of vertical well and horizontal well mixed well network were analyzed.