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Evaluation of residual hydrocarbons effect on CO2 injectivity in depleted chalk reservoirs

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.

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.

  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.