Pioneering Sustainable Well Cementing in Brunei: Reduced Portland Cement Blends With Locally Sourced Fly Ash

Abstract The oil and gas industry in Brunei is increasingly focused on sustainable practices, particularly in well cementing, which is a crucial operation with environmental considerations. To contribute to this effort, the service company has introduced a novel reduced Portland cement (RPC) blend system. This system incorporates locally sourced fly ash, which provides a high-performance and environmentally responsible solution that aligns with the commitment to sustainable development. The RPC system prioritizes environmental stewardship with a decrease in carbon dioxide (CO2) emissions associated with clinker production through a 25% reduction in Class G Portland cement content. Additionally, the system uses readily available fly ash, a recycled material, to minimize reliance on imported ordinary Portland cement (OPC) and strengthen supply chain efficiency. This focus on localization not only reduces transportation emissions but also fosters a more adaptable and resilient supply network in Brunei. Rigorous laboratory tests have qualified the RPC blend system and have demonstrated that RPC blends maintain or even exceed the compressive strength of conventional, higher-density OPC systems. This helps ensure effective wellbore isolation, despite the lower density of the RPC blend, a crucial factor for long-term well integrity. Additionally, RPC blends exhibit lower equivalent circulating densities, which makes pressure management during wellbore construction simpler and enhances operational efficiency. The RPC system provides several advantages beyond its environmental benefits. The enhanced ductility and toughness of these blends, compared to traditional cement, allow the cement sheath to better withstand downhole stresses and strain throughout the well's life. This promotes long-term zonal isolation and helps mitigate the potential risk of leakage. Furthermore, the lower permeability of RPC blends provides superior resistance to corrosive fluid and gas that migrate through the wellbore to help ensure the long-term integrity and production efficiency of the well. Since May 2023, the RPC blend system has been successfully implemented in Brunei. This innovative approach not only minimizes the environmental impact but also delivers strong wellbore integrity. The RPC blend system represents a significant advancement in sustainable well cement operations, which paves the way for a more environmentally acceptable future for the oil and gas industry in Brunei.