Organic Acid Interactions in Geological Reservoirs

Organic acids, particularly low-molecular-weight species such as acetic, formic and oxalic acids, play a central role in controlling the chemistry, porosity and mineralogy of sedimentary reservoirs. These acids originate during the thermal maturation of kerogen and biodegradation of organic matter, migrating through pore networks and reacting with host minerals. In carbonate settings, organic acids selectively dissolve calcite and dolomite, enlarging existing voids and generating secondary porosity. In siliciclastic environments, acid leaching of feldspars and cement phases can open microfissures, although the intensity of dissolution depends on grain sorting, cement distribution and fluid flow pathways. The mobilisation of trace metals, changes in pore-water acidity and inhibition of secondary mineral precipitation all influence fluid transport, reservoir quality and the distribution of hydrocarbons and aqueous minerals. Understanding these processes is critical for optimising hydrocarbon recovery, assessing contaminant migration and evaluating the long-term stability of subsurface CO₂ storage.

Research from Nature Portfolio

Recent studies have demonstrated that low-molecular-weight organic acids produced during early stages of thermal maturation exert a significant influence on trace element migration in organic-rich source rocks. Laboratory simulations reveal that acid generation peaks prior to primary hydrocarbon release, with acid yields closely correlating to the leaching rates of uranium, copper, lead, zinc and other metals. Statistical analyses of borehole geochemical data confirm that organic acid-driven dissolution during kerogen breakdown reduces uranium content and total organic carbon with increasing burial depth, highlighting the role of organic acids as agents of trace metal mobilisation in deep sedimentary basins.

Organic Acid Interactions in Geological Reservoirs publication trend

The graph below shows the total number of articles in organic acid interactions in geological reservoirs across all publications each year (not limited to Nature Index journals).

Technical terms

Low-molecular-weight organic acids: Small organic acids (typically C1–C6) formed during thermal maturation of organic matter that can dissolve minerals in pore spaces.

Kerogen: Insoluble organic matter in sedimentary rocks that generates hydrocarbons and organic acids upon heating.

Diagenesis: The suite of physical, chemical and biological processes transforming sediment into rock at relatively low temperature and pressure.

Secondary porosity: New pore space created after initial sediment deposition, often through mineral dissolution by reactive fluids.

Reactive transport modelling: Numerical simulation of coupled chemical reactions and fluid flow used to predict mineral alteration and porosity evolution.

References

1. Evaluation of uranium migration during the maturation of hydrocarbon source rocks. Scientific Reports (2024).
2. Dissolution of Different Reservoir Rocks by Organic Acids in Laboratory Simulations: Implications for the Effect of Alteration on Deep Reservoirs. Geofluids (2021).
3. Modelling diagenetic reactions and secondary porosity generation in sandstones controlled by the advection of low‐molecular‐weight organic acids. Basin Research (2024).
4. The Dissolution Behavior of Feldspar Minerals in Various Low-Molecular-Weight Organic Acids. Materials (2023).