Duct Pipe Optimation for Geothermal Fluid in Water Dominated Reservoir

Abstract

A single pipe model for simulating the flow of geothermal fluid in a well, in a two phase flow line and in a steam line is used to determine optimum diameter of casing, two phase line, steam line as well as optimum thickness of insulator. The inlet parameters such as pressure, temperature, diameter, mass flow and steam quality are the main factors which influence the pressure loss are used as a basis of main optimization. There are two problems. The first is production restriction and the second is investation of duct pipe that has cost limitation. Both problems can be solved by doing the optimization of duct pipe, involving the technical and economical aspects. WellSim simulator is used to predict the pressure loss in the bottom hole and surface, and on the other way around. The output, namely pressure, mass flow rate, temperature, dryness and enthalpy of the wellhead are used as input data for PipeSim. PipeSim is a simulator used for calculating the pressure loss in the surface and then they are used to calculate power output from turbine and net present value. PipeSim simulator provides the parameters to determine optimation. In the present study data of well Sibayak-05 (Sibayak field) is used for determining optimum diameter of casing, surface line and insulation optimum thickness. The result shows that optimum production casing diameter is 13-3/8 in, inside diameter of two phase duct pipe is 0.5368 m (outside diameter is 0.5588 m), insulation pipe of two phase flow is 2 cm, inside steam pipe diameter is 0.2476 m (outside diameter is 0.2731 m ), pipe insulation thickness for steam flow is 7.5 cm.