Models To Estimate The Productivity Of Horizontal Wells And Their Application To Optimization Designs On Segmented Perforations

To simplify the problem of the non-uniform inflow profile along the whole horizontal well bore, the well bore is partitioned into many segments. Using the pseudo-three-dimension method and additionally concerning the influence of formation damage and perforation-inflow converge, the correlation equation between reservoir flow rate and pressure difference for each segment is obtained. On the hypothesis that the pressure drop along the horizontal well is caused by friction and acceleration, a general pressure drop expression, based on the fresh proposed idea of equivalent roughness of well bore and the principles of conservation of mass and momentum, is established,and is also verified to have a high degree of accuracy. Moreover, the established models, coupled together to estimate the well productivity, are validated by comparing the calculation results with the field data, and good agreement is found between them. Finally, from the angle of technical economy and for the purpose of obtaining the maximum economic benefit, integrating the established models with the water cone behaviors of bottom water drive reservoirs and the relationship between the water cut of well-produced fluid and time, a method to optimize the horizontal well length is proposed, and the calculation result suggests this method can be applied to the design of reservoir engineering and the well management. As such, the offered models provide a theoretical foundation for long horizontal wells to be partially and effectively exploited by segmented perforations, thus to ensure maximum economic profits in horizontal wells.