Objective  Polymer-surfactant binary flooding technology is an important part of the old oilfield tertiary oil recovery. With the proposal of the national dual carbon goals, there are increasingly stringent requirements for carbon emission reduction in oil and gas field development. In this context, in order to achieve carbon emissions reduction in the oilfield binary flooding ground system, it is necessary to construct a complete polymer-surfactant binary flooding ground system carbon emissions accounting method to assess the direct and indirect carbon emissions level of the polymer-surfactant binary flooding ground system from an overall perspective and put forward practical emissions reduction countermeasures.

Method The polymer-surfactant binary drive formulation and injection system adopted the overall process of "centralised preparation-decentralised injection". The gathering and treatment system utilized the technology of tandem oil gathering and closed dehydration. The wastewater was treated using the technology of “regulating oil removal + air flotation + microbial treatment + filtration”. Based on the process route of polymer-surfactant binary flooding ground engineering, the boundary of carbon emissions was identified, the carbon emission factors were clarified, a complete carbon emission accounting method for the polymer-surfactant binary flooding ground system was constructed, the carbon emission activities were accounted for, the proportion of carbon emissions was analyzed, and the countermeasures for emission reduction were put forward.

Result The carbon emissions intensity (The mass of carbon dioxide produced by producing 1 ton of oil) by the polymer-surfactant binary flooding ground system was 126.52 kg/t. The direct carbon emission intensity was 14.66 kg/t, the indirect carbon emissions intensity was 126.62 kg/t, with a carbon sink intensity of 14.76 kg/t. Indirect emissions accounted for 89.62% of total emissions, with electricity consumption contributing 88.24% of indirect emissions, representing the primary emission source of polymer-surfactant binary flooding ground system.

Conclusion To mitigate the high electricity consumption associated with polymer-surfactant binary flooding surface facilities, six energy-saving strategies are proposed: Firstly, selecting high-efficiency equipment and motors. Secondly, adopting combinations of multiple small-capacity units. Thirdly, controlling the water cut of produced fluids. Fourthly, optimising key process parameters. Fifthly, utilising the gravitational potential of fluids to reduce lifting energy demand. Sixthly, integrating renewable energy sources with polymer-surfactant binary flooding ground system. These recommendations provide practical guidance and development directions for the low-carbon transformation of polymer-surfactant binary flooding ground systems.