Background
The injection of CO₂ in depleted oil fields can provide new opportunities to prolong and revamp an otherwise unused resource.

The effect of CO₂ injectivity on the residual hydrocarbons in depleted chalk oil fields will be investigated to gain insight into undesired reactions between hydrocarbons and CO₂, including presence of solid bitumen, asphaltene precipitation and hydrocarbon moveability.

This project will address the organic residual fraction in the matrix of the chalk reservoir. Despite it is well-known that most of the in-place hydrocarbons are left behind during production, this issue has yet not been investigated in any detail.

The results on specific risks for residual hydrocarbons moveability/clogging will translate directly into the decision-making process of the applicability of a depleted chalk reservoir as storage site. It will further address issues related to potential leakage due to CO₂-induced hydrocarbon moveability.

Objectives
The project will investigate effect of residual hydrocarbons in non-flooded and water-flooded chalk reservoirs on CO₂ injectivity. The project will therefore help de-risk depleted oil field CO₂ storage sites and may have a substantial impact on emission reduction and thus on reaching the goal of atmospheric CO₂ reduction in Denmark.

Expected results

1. Characterization of the residual hydrocarbons pre-CO₂ flooding.
2. Characterization of the residual hydrocarbons post-CO₂ flooding experiments on core samples at reservoir condition.
3. Determinate the impact of CO₂ injection on the residual hydrocarbon composition(s), in particular the fractions of moveable hydrocarbons and core clogging bitumen.