Conceptual Design for Carbon-Neutral Oil Production System in Brazilian Pre-Salt Fields

Abstract

Summary Brazilian pre-salt oil fields usually have an original CO2 content. In current production systems, it is already commonplace to consider the separation and reinjection of this original CO2, reducing emissions and, simultaneously, supplying Enhanced Oil Recovery (EOR). However, the design of a carbon-neutral offshore production system (assumed a FPSO unit - Floating, Production, Storage and Offloading) requires added infrastructure to capture, compress, transport and reinject CO2 from third party sources. On this scenario, onshore dry CO2 sources shall be connected to the FPSO by a dedicated pipeline, to offset CO2-intensive production activities. The onshore CO2 stream is directed to the reinjection gas stream, enhancing the well-known capture and utilization (EOR) process that is already in course. As a proof-of-concept, the UNISIM-III model representing a fractured karst pre-salt carbonate reservoir was used for flows simulations and economic evaluations with additional assumptions regarding the added CO2 volumes. There are two main sources of economic gains, the first being the incremental oil production from Enhanced Oil Recovery (EOR) and the second the carbon credits for the captured volumes. On the other hand, the added CAPEX challenges the feasibility of this enterprise, leading to economic loss in the deterministic economic scenario for an average case of carbon pricing. Finally, it is possible to define the minimum carbon price scenario that delivers a carbon-neutral oil production that is economically interesting in Brazilian offshore context.