Perforated Horizontal Well Productivity Analysis

More and more horizontal wells are applied while drilling technology is becoming perfect gradually. Perforation, being one of completions and stimulation, is used widely. So it is very important to study the productivity model of perforating horizontal well. In this study, a comprehensive model has been successfully built for perforated horizontal well. The Green's functions and source function solutions were used for the development of the reservoir pressure response due to the 3D convergence of flow toward perforations. The long-time asymptotic solutions were first derived under pseudo-radial flow. Then, the approach of additional drawdown due to completion pseudo-skin was developed to express the pressure response under boundary-dominated flow.The model strictly considers the influence of completion parameters on both reservoir pressure and wellbore hydraulics. The non-liner coupling matrix equations are discretized and solved numerically. The semi-analytical is capable of incorporating the effects of non-uniform mechanical skin and non-Darcy flow. Formulae were derived to predict additional pressure drops due to mechanical skin and non-Darcy effect in the perforation radial flow and wellbore radial flow.Pseudo-pressure function was used to extend the solutions of oil wells to gas wells.The horizontal wells have more concentrated flux and pressure drop on the heel end sidedue to gas expansion and acceleration. Non-Darcy flow has severe effect on the gasproductivity.A programme based on Newton-Raphson iterative method was developed to solvethe computational model. The model was verified by actual example. Sensitivity analysiswas performed for perforation parameters. The guidelines of optimization of perforationhave been developed.