Horizontal well length optimization considering wellbore hydraulics

Abstract

Horizontal wells covering entire length of the reservoirs are not economically suitable. Frictional pressure drops increases with the increase in well length and flow rates. Optimal Horizontal length is estimated through economic analysis i.e. Net present Value of the project (NPV). Well construction costs including incremental costs of drilling horizontal section, friction losses in horizontal section, Hydrocarbon prices and Drainage area affect NPV. This thesis work estimates NPV and Productivity Indices of horizontal well projects with the use of simulation results under operating conditions of draw drawdown limits and constant Bottom hole flowing pressures using Finite conductivity concept. Horizontal wells assuming frictionless wellbores are also discussed.The results of NPV and PI are used to estimate the optimal length of horizontal wellbore in this work. Relatively shorter well lengths were found to be more economical than the lengthier ones in every case. Well bore flow rates of 1600 stb/day in the case of well bore roughness variation didn t decrease productivity to high extent . Higher flow rates such as a minimum of 2600 stb/day were reported to be involved in decreasing productivity for well lengths of 3000-4000 ft. for diameter of 2.5 inches. Well length optimization through objective functions based on NPV, flow rates and bottom hole flowing pressures are possible future works.