Unlocking the Potential of Flare Gas Recovery: A Case Study in PDO's Zero-Routine Flaring Initiative

Abstract

ABSTRACT Flare Gas Recovery is a pivotal strategy in achieving Zero-Routine Flaring objectives in the oil and gas sector. This paper presents key insights from one of Petroleum Development Oman's (PDO) largest flare recovery endeavors, focusing on the design of Atmospheric Flares (AP) and Gas Recovery systems. The project targeted the recovery of associated gas from a major PDO oil production station, encompassing 12 atmospheric tanks. The recovered gas routed through Gas Recovery system, is to be integrated into the available high-pressure grid for reinjection system as a final sink. The challenge associated with this sink is that the recovered gas to be boosted from tank pressure upto 2.5 barg. A comprehensive feasibility study evaluated more than 15 potential technologies of which 6 have been shortlisted as promising options for the project. These are Gas Ejector, Gas-to-Power, liquid Eductor, Liquid Ring Compressor, Screw Compressor, and Rotary Vane Compressor. Due to motive gas flow constraints, and vented gas low pressure, gas ejector and gas-to-power were discarded. Screw compressor was on the other hand discarded due to the gas quality and reliability of such machines for process gas. Ultimately, the Liquid Ring Compressor, Rotary Vane Compressor and liquid educator emerged as viable options. Further evaluation of these three options against criteria such as economics, overall energy efficiency, capital and operational expenditure, operational flexibility, and system standardization were conducted. The Rotary Vane Compressor was found to be the most optimum solution for this project, offering an optimized design for low flow rate and pressure scenarios. Using the evaluation criteria, Rotary Vane Compressor offers significant benefits including higher efficiency with reduced power consumption, lower capital and operational costs and attractive economics values. This technology enabled the project to cut the capital expenditure by half compared to initial estimates and successfully achieve zero-routine flaring by recovering around 100% of routine flare gas. The choice of the Rotary Vane Compressor addresses various gas recovery challenges, ensuring zero routine flare, eliminating gas emissions with a double seal system, reducing costs, and providing an easily standardized solution for future projects. Most published papers in this area tend to address scenarios with either low pressure ratios or high flow rates, leaving a gap in the literature for solutions catering to systems with both high-pressure ratios and low flow rates. This project faced potential cancellation due to the lack of viable options for such systems, until we identified the Rotary Vane Compressor as a suitable solution. Following a site visit to assess its feasibility, numerous advantages of rotary vane were demonstrated, including low capital expenditure, low operational expenditure, minimal maintenance requirements, economic benefits, small footprint, and alignment with zero routine flaring goals. This success story highlights the importance of innovative solutions and thinking outside the box when faced with challenging engineering problems. Our experience with the Rotary Vane Compressor can serve as a valuable case study for future projects in similar contexts.