Chemical EOR Produced Water Management at Malay Basin Field

Abstract

This paper examines the requirements, mechanisms and mitigation options for management of produced water from chemical EOR field. As the application of Chemical EOR at Angsi field, the produced water is expected to contain some levels of injected chemicals such as surfactant and polymer. A key concern is the potential impacts on marine environment in which current field facilities design is not cater for the produced chemicals management. A detail laboratory studies were conducted such as toxicity assessment on local marine fish, grouper indicated the polymer is practically nontoxic with LC50>500 mg/L, and the surfactant is relatively toxic with LC50=1.23 mg/L. The polymer also poses significant environmental concern as it has low biodegradation property with less than 20% are biodegradable in 28 days. Complicating this situation, alterations of produced fluids physical and chemical properties are also demonstrated. Laboratory analyses of ASP produced fluids predicted higher fluids viscosities, with stable and higher emulsion formed (increment up to 40%) which contributed to higher basic sediments and water (BS&W) percentage. Even minimal scale issues is predicted, mentioned conditions had already contributed significant impact on existing facilities and chemical dosage efficiency and requirements. The complexities in the conditions render managing ASP breakthrough required defined EOR produced fluid management. In view of current facilities limitations, the study was focused in identifying suitable chemicals and mechanicals mitigation options to treat and manage surfactant and polymer residues toward Angsi Chemical EOR implementation. Recommended solutions were based on laboratory studies, current facilities configuration, technical and regulatory acceptance and economic viability as the actual impacts varied depending on fluids composition and characteristic of the receiving environment.