FLOW MODEL AND PRESSURE DISTRIBUTION IN THE RE-INJECTION PIPELINE AHUACHAP¡N-CHIPILAPA, EL SALVADOR

Abstract

In the Ahuachap·n Geothermal Field the re-injection pipeline used to connect the flasher unit with the injection zone in Chipilapa has a total length of 6.02 km. The main flow is carried by a 24" pipe diameter of 4647 length until the Ch-7bis pad where it is distributed into the injector wells Ch-7, Ch-7bis and Ch-9. Because the pipeline is operated by gravity "open channel" the flow capacity is limited to the elevation between the flasher and any of the injector wells (dh). In this way using the wells Ch-7bis and Ch-9 a dh of 18.75 m give a maximum flow of 326 kg/s and if a residual water of 345 kg/s is operated 19 kg/s must be spilled into the waste channel. The use of the wells Ch-7 and Ch-9 decrease the dh to 11.7 m given a maximum flow of 239 kg/s rising the spilling water to 106 kg/s. To overcome this problem the pipeline must be operated as "filled pipe" by pressure gradient. Under this mode estimations of the pressure distribution along the pipeline give a maximum flow of 495 kg/s using by order the injector wells Ch-7, Ch-7bis and Ch-9.