Technical Validation of Oil Production Greenhouse Gas Emissions Estimator Using Field Data from Thermal Enhanced Oil Recovery Operations

Thermal enhanced oil recovery (TEOR) has gained attention due to its greenhouse gas (GHG) emissions and carbon intensity (CI). These emissions have regulatory implications in programs such as California’s Low Carbon Fuel Standard (LCFS). The LCFS, implemented by the California Air Resources Board (CARB), aims to reduce the CI of supplied fuels. CARB uses the Oil Production Greenhouse Gas Emissions Estimator (OPGEE) for CI evaluation of crude oils. This study assesses OPGEE’s accuracy using detailed field data from operating TEOR fields. We conducted a five-stage analysis to identify the causes of discrepancies between CARB’s published CI results and field data from a crude oil production company in San Joaquin Valley. After adjusting inputs, model settings, and boundary conditions to better represent specific field operations, we found that the CI difference between OPGEE estimates and field data decreased from 196% to approximately 10%. This represents a substantial improvement in model accuracy. Our analysis identified distinct elements responsible for the persistent discrepancy: (1) using default literature values instead of field data in OPGEE accounts for nearly 50% of the total observed difference; (2) incorporating detailed operator data can reduce the gap between modeling results by half; and (3) variations in system boundaries and accounting methods contribute about 30% of the total difference. Using high-quality data and maintaining consistent system boundaries can significantly reduce discrepancies between model results and operator data. Building on these findings, we also evaluated how various mitigation strategies affect CI calculations, including the integration of solar photovoltaics into oil and gas operations as a representative clean energy approach.