Collective Produced Water Reinjection (PWRI) Feasibility Assessment for Malaysian Oilfields

Abstract

Abstract Produced water production from oil and gas operation across the globe is estimated to be 3:1 ratio of oil production and usually continue to increase throughout the oilfield life. Thus, if not managed properly, excessive produced water discharge may lead to pollution and severe environmental impact, especially if not properly treated and managed. Treatment and disposal costs remain the primary issue with the ongoing global push towards transition to cleaner energy and Zero Liquid Discharge, technology innovations in water treatment, use and reuse are required. This paper aims to present the findings from a collective produced water reinjection (PWRI) feasibility assessment for selected Malaysian oilfields. The main constituents of produced water consist of dissolved and dispersed oil and gas compounds, dissolved formation minerals, production chemical compounds and production solids such as scale, waxes, etc. PWRI feasibility assessment addressing injectivity was conducted to establish PWRI water specification (i.e. oil concentration, particle size and concentration etc.). Other evaluation aspects including water compatibility & scaling study, reservoir souring, and corrosion study is also evaluated as part of a wholesome approach to PWRI feasibility assessment. Based on the study, oil in water (OIW) limit of 6-20 ppm, recommended total suspended solids (TSS) limit of 5-20 ppm for particle size control ranging between 2-3 μm is established. In general, low scaling tendency and corrosion potential were observed for almost all fields, and reservoir souring assessment conducted for one field shows potential due to VFA presence and shall further be studied, these can later be further addressed via scale & corrosion inhibitor injection and biocide treatment at the water injection side. Collective PWRI feasibility assessment was conducted to compare and consolidate the requirement for PWRI based on technical consideration on injectivity, scaling, reservoir souring and corrosion. The systematic approach for a wholesome evaluation covering subsurface and surface elements with findings are presented and discussed accordingly.