Innovative and Cost-Effective Approach to Deal with the Challenges of Trapped Gas and Flashing in Produced Water System

Abstract The purpose of this paper is to present a case study on the challenges faced in handling produced water expansion project due to trapped gas and flashing which may lead to process safety event. This case study explains how the problem was solved during the integrated field development project at one of Company onshore's largest oil fields, which enabled the timely start-up of an extra 200,000BWPD capacity for handling produced water. Oil production facilities are equipped with a produced water system, which includes primary and secondary treatments to ensure the produced water meets the necessary standards for reservoir reinjection and water disposal. In the context of integrated field development, two new disposal tanks and their associated pumping systems were added. However, during the commissioning phase of these tanks, high back pressure was noted, affecting the performance of all running five gas oil separation processing trains. Produced water is not fully stabilized liquid, therefore dissolved gases flashed out once exposed to low pressure system plus the flashing that occurs along the line creates gas trapped in the highest point of the header which increases the back pressure in the header. This was finally crossed check with the piping network simulation. Based on field trail and dynamic simulation the successful implementation of the highest point close loop flash gas removal to low-pressure system indicates how trapped gas can be efficiently removed to secure the additional throughput of the water disposal system to cater to the future expansion demand of the oil and gas fields. Oil and gas producers may consider this provision in the inherent safety design of the produced water handling system. This paper presents a case study of how Company solved the problem of trapped gas and flashing in the produced water handling system at one of its largest oil fields. The remedial exercise involved installing a close loop flash gas removal system at the highest point of the header, which reduced the back pressure and improved the performance of the gas oil separation trains. Early stage identification & evaluation of such instances can avoid disturbance in process safety events and timely commissioning of new facilities This solution enabled the timely start-up of an extra 200,000BPWD capacity for handling produced water and improved the process safety and reliability of the facility.