Salt Water Disposal System Modification during Low Water Flow Rates from Khurais Fields

摘要

The Khurais Central Processing Facility (KhCPF) includes four salt water disposal (SWD) systems distributed among four oil trains. Each SWD system is comprised of one water-oil separator (WOSEP), three 33% salt water disposal pumps, and necessary piping from pump discharge, which are terminated at the water injection header. The SWD system has been designed to accommodate ultimate produced formation water (30% water cut from Khurais fields); however, due to the unexpected very low water flow rate from the fields since the commissioning period of the facility, SWD systems are encountering inconvenient operation and frequent equipment failure. To eliminate the operational difficulties and protect the major pieces of equipment, various options were evaluated. The most optimum solution found was to divert salt water from three WOSEPs to a depressurizing vessel by pressure transfer and then recycling it back to a single train. The benefits from modification included — energy conservation by minimizing the running of salt water disposal pumps, reducing the environmental impact and huge operational flexibility for the facility — even if the water cut increases in the future. This modification is expected to be one of the best solutions for the gas-oil separation plants (GOSPs) that that are facing operational difficulties due to low water flow rates from an oil field. This paper describes the modifications in a salt water disposal system, hydraulic assessments, HAZOP study and the field modification that are planned in the KhCPF for the recycling of salt water from the WOSEP to the depressurizing vessel.