Heat Engine for Co-Generating Electric Power Plant

Abstract

Utilization of geothermal energy within the Oil Industry is a topic that the Oil Industry today is aware of but no large scale systems, like the Co-Generation system, has yet been implemented to existing subsea installations.

The Co-Generation System is to be connected to the separator and receive produced water to generate power through an Organic Rankine Cycle primarily to supply the re-injection pump with electric power.

The biggest challenge regarding implementation concerning the Co-Generation System is that SSC like the heat exchanger and Organic Rankine Cycle have never before been placed subsea and there are therefore limited experience and knowledge related to this type of system.

Calculations made shows that the best power generation technique is to apply an Organic Rankine Cycle where the other option was the Kalina Cycle. In addition in some cases the ORC could generate enough power to supply the re-injection pump and other parts of the subsea processing system e.g. boosting system.

One of the biggest challenges regarding the operation of the Co-Generation System is to obtain the highest possible net power output from the ORC since the produced water volume flow is not constant and is increasing over time.

Materials selection regarding the Co-Generation System is mostly characterized by Type 25Cr Duplex where all parts of the system that are exposed to the produced water should be Type 25Cr Duplex. Materials that are exposed to the ambient seawater should be coated and protected by sacrificial anodes.