Surface Facilities for a Giant Thermal EOR Project - Cost and HSE Implications of Alternative Fuels for Steam Generation

Abstract

AbstractThis paper describes three different surface facility configurations for an Enhanced Oil Recovery (EOR) project in the Orinoco Oil Belt (OOB), where steam-based, thermal EOR processes are planned to be used at a very large scale.After an initial EOR screening process, four steam-based, thermal EOR technologies werepre-selected as potentially suitable options for the field: Cyclic Steam Stimulation (CSS), Steam Flooding (SF), Steam-Assisted Gravity Drainage (SAGD), and Horizontal Alternating Steam Drive (HASD). In the conceptualization phase, several alternative cases were consideredfor each technology, including variations in injection rates, deployment schedule, and well spacing. All these subsurface cases could be condensed into two design cases for the surface facilities: a low steam generation rate case, and a high steam generation case. However, due to the very large project size and the potential competition with other developments, uncertainty existed about the amount of natural gas that could be available as fuel for the steam generation, as well as about the environmental implications of the EOR operations.To handle these uncertainties, two alternative fuels were considered in addition to natural gas: coke and extra-heavy oil (XHO); a fourth option consisting in a combination of gas and coke was also included in the study. Surface facilities for the two steam generation rates and for the four different fuel alternatives were conceptualized obtaining class V cost estimates. Environmental impact in terms of CO2 emissions and fresh water demand was also evaluated for all the design cases.As expected, natural gas is the fuel that leads to lower cost facilities, as well as to a smaller environmental footprint. On the other hand, in the probable case that not enough gas is available, the decision to use coke or XHO as an alternative fuel will depend on the relative weight given to the economic and environmental factors, which are very related to the EOR technology selected for the field. Thus, this work demonstrates how the integration of the surface facility designs with the reservoir studies allows obtaining very useful insights on the advantages, risks and drawbacks of each EOR technology. This innovative subsurface-surface integrated approach sets the basis for high quality project decisions.