| 1. |
- Braga, R., et al.
(författare)
-
Modelling methane hydrate stability changes and gas release due to seasonal oscillations in bottom water temperatures on the Rio Grande cone, offshore southern Brazil
- 2020
-
Ingår i: Marine and Petroleum Geology. - : Elsevier. - 0264-8172 .- 1873-4073. ; 112, s. 1-15
-
Tidskriftsartikel (refereegranskat)abstract
- The stability of methane hydrates on continental margins worldwide is sensitive to changes in temperature and pressure conditions. It has been shown how gradual increases in bottom water temperatures due to ocean warming over post-glacial timescales can destabilize shallow oceanic hydrate deposits, causing their dissociation and gas release into the ocean. However, bottom water temperatures (BWT) may also vary significantly over much shorter timescales, including due to seasonal temperature oscillations of the ocean bottom currents. In this study, we investigate how a shallow methane hydrate deposit responds to seasonal BWT oscillations with an amplitude of up to 1.5 °C. We use the TOUGH + HYDRATE code to model changes in the methane hydrate stability zone (MHSZ) using data from the Rio Grande Cone, in the South Atlantic Ocean off the Brazilian coast. In all the cases studied, BWT oscillations resulted in significant gaseous methane fluxes into the ocean for up to 10 years, followed by a short period of small fluxes of gaseous methane into the ocean, until they stopped completely. On the other hand, aqueous methane was released into the ocean during the 100 years simulated, for all the cases studied. During the temperature oscillations, the MHSZ recedes continuously both horizontally and, in a smaller scale, vertically, until a permanent and a seasonal region in MHSZ are defined. Sensitivity tests were carried out for parameters of porosity, thermal conductivity and initial hydrate saturation, which were shown to play an important role on the volume of methane released into the ocean and on the time interval in which such release occurs. Overall, the results indicate that in a system with no gas recharge from the bottom, seasonal temperature oscillations alone cannot account for long-term gas release into the ocean.
|
|
| 2. |
- Iglesias, Rodrigo S., et al.
(författare)
-
Carbon capture and geological storage in Brazil : an overview
- 2015
-
Ingår i: Greenhouse Gases. - : Wiley-Blackwell. - 2152-3878. ; 5:2, s. 119-130
-
Tidskriftsartikel (refereegranskat)abstract
- Brazil is recognized for possessing a low carbon-intensive energy matrix, with most of its power being generated from hydroelectricity. Its greenhouse gas emissions profile is dominated by deforestation and land-use change. Despite this characteristic, the country has been committed to the development of carbon capture and geological storage (CCS) research since this technology started to be recognized as a relevant solution for greenhouse gas emission reductions. This development has gained attention recently owing to the beginning of the production of pre-salt reservoirs, which may contain significant amounts of CO2 in the produced fluids. The work has been carried out mostly through the efforts of the academia and industrial enterprises. This paper presents a summary and a brief description of the recent activities being carried out by these sectors, aiming to develop and promote CCS in Brazil.
|
|
| 3. |
- Iglesias, Rodrigo S., et al.
(författare)
-
Characterization and modeling of CO2‐water‐rock interactions in Hygiene Sandstones (Upper Cretaceous), Denver Basin, aimed for carbon dioxide geological storage
- 2018
-
Ingår i: Greenhouse Gases. - : Wiley-Blackwell. - 2152-3878. ; 8:4, s. 781-795
-
Tidskriftsartikel (refereegranskat)abstract
- Carbon capture and geological storage are among the most valuable technologies capable of reducing CO2 emissions. Long‐term interactions between CO2 and a reservoir, and the integrity of geological formations, are key factors in the selection of adequate reservoirs for permanent storage. Numerical models of CO2‐water‐rock geochemical interactions are often employed to predict the fate of CO2 stored in a reservoir over time. The Hygiene Sandstone, in the Denver Basin, Colorado, USA, is a geological formation with potential for CO2 storage, and was therefore studied in this work, in which we collected and characterized outcrop samples in order to supply the input parameters for numerical simulations. Four representative thin sections of Hygiene Sandstone outcrops were quantified in terms of detrital constituents, diagenesis, and porosity on the basis of conventional petrography. Sandstone mineralogy included, in decreasing order, quartz, K‐feldspar, muscovite, albite, illite, smectite, kaolinite, poikilotopic calcite, and siderite. Porosity ranged from 4% to 13%. A geochemical modeling study of CO2‐water‐rock interactions performed with two characterized samples and brine data from the Hygiene Sandstones, simulating reservoir conditions, suggested that the mineralogy of the sandstone is quite stable under the conditions that were tested and only minor mineralogical and porosity alterations would occur within a thousand years of storage.
|
|
| 4. |
- Siqueira, Tiago A., et al.
(författare)
-
Carbon dioxide injection in carbonate reservoirs : a review of CO2-water-rock interaction studies
- 2017
-
Ingår i: Greenhouse Gases. - : Wiley. - 2152-3878. ; 7:5, s. 802-816
-
Tidskriftsartikel (refereegranskat)abstract
- Carbon dioxide injection in geological formations is currently a common procedure in several reservoirs worldwide. More recently, it has been considered a permanent storage solution, avoiding emission to the atmosphere from large industrial sources. Also, it is largely employed in the oil & gas exploration industry, for enhanced oil recovery (EOR) operations. However, it is a known fact that injection of large amounts of CO2 into geological reservoirs may lead to a series of alterations due to chemical and physical interactions with minerals and fluids, especially in carbonate or carbonate-rich reservoirs. Experimental and numerical models have been employed in many studies in the past, to investigate these effects on the geological environment. So far, most of these studies focused on siliciclastic formations, whereas carbonate reservoirs, which are known to be much more chemically reactive when interacting with CO2, were much less investigated. We present a review of experimental and numerical models that have been employed for studying CO2-water-rock interactions, and their application to the investigation of the impact in carbonate reservoir quality and integrity caused by the injection of carbon dioxide.
|
|
