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Water injection into the Ekofisk-reservoir was introduced in 1987 to enhance oil recovery (EOR) d... more Water injection into the Ekofisk-reservoir was introduced in 1987 to enhance oil recovery (EOR) dissolution and precipitation by exposing chalk to various brines at reservoir conditions, which further increased deformation of chalk matrix. This deformation affected mechanical properties of the tested samples and is referred to as water weakening of chalk. This thesis has focused on identifying mineral changes and mapping the distribution of precipitated mineral during flooding of samples which have an artificial fracture and will compare hollow cylinder to intact chalk cores. Methods used to achieve a mineralogic map are:
Energies, May 22, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Minerals, Mar 15, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Energy & Fuels, Apr 20, 2023
Energies, Jun 1, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Energies
Analyses of fine-grained rocks like shales, cherts, and specifically chalk are challenging with r... more Analyses of fine-grained rocks like shales, cherts, and specifically chalk are challenging with regards to spatial resolution. We propose a “toolbox” to understand mineralogical alteration in chalk, especially those induced by non-equilibrium fluids or polymers and silicates during production of hydrocarbons. These data are fundamental in experiments related to improved/enhanced oil recovery (IOR/EOR) research with the aim to increase hydrocarbon production in a sustainable and environmentally friendly process. The ‘toolbox’ methods analyse rock–fluid or polymer–rock interaction and can be applied to any fine-grained rock type. In our ‘toolbox’, we include methods for routine analysis and evaluate the economic side of the usage together with the complexity of application and the velocity of data acquisition. These methods are routine methods for identification and imaging of components at the same time by chemical or crystallographic means and here applied to petroleum geology. The ...
Energies
This experiment was designed to study the water-weakening effect of artificially fractured chalk ... more This experiment was designed to study the water-weakening effect of artificially fractured chalk caused by the injection of different compositions of brines under reservoir conditions replicating giant hydrocarbon reservoirs at the Norwegian Continental Shelf (NCS). NaCl, synthetic seawater (SSW), and MgCl2, with same ionic strength, were used to flood triaxial cell tests for approximately two months. The chalk cores used in this experiment originate from the Mons basin, close to Obourg, Belgium (Saint Vast Formation, Upper Cretaceous). Three artificially fractured chalk cores had a drilled central hole parallel to the flooding direction to imitate fractured chalk with an aperture of 2.25 (±0.05) mm. Two additional unfractured cores from the same sample set were tested for comparison. The unfractured samples exposed a more rapid onset of the water-weakening effect than the artificially fractured samples, when surface active ions such as Ca2+, Mg2+ and SO42− were introduced. This ins...
Minerals, 2022
Chalk is a very fine-grained carbonate and can accommodate high porosity which is a key character... more Chalk is a very fine-grained carbonate and can accommodate high porosity which is a key characteristic for high-quality hydrocarbon reservoirs. A standard procedure within Improved Oil Recovery (IOR) is seawater-injection which repressurizes the reservoir pore pressure. Long-term seawater-injection will influence mineralogical processes as dissolution and precipitation of secondary minerals. These secondary minerals (<1 micrometer) precipitate during flooding experiments mimicking reservoir conditions. Due to their small sizes, analysis from traditional scanning electron microscopy combined with energy dispersive X-ray spectroscopy is not conclusive because of insufficient spatial resolution and detection limit. Therefore, chalk was analyzed with high-resolution imaging by helium ion microscopy (HIM) combined with secondary ion mass spectrometry (SIMS) for the first time. Our aim was to identify mineral phases at sub-micrometer scale and identify locations of brine–rock interacti...
Water injection into the Ekofisk-reservoir was introduced in 1987 to enhance oil recovery (EOR) d... more Water injection into the Ekofisk-reservoir was introduced in 1987 to enhance oil recovery (EOR) dissolution and precipitation by exposing chalk to various brines at reservoir conditions, which further increased deformation of chalk matrix. This deformation affected mechanical properties of the tested samples and is referred to as water weakening of chalk. This thesis has focused on identifying mineral changes and mapping the distribution of precipitated mineral during flooding of samples which have an artificial fracture and will compare hollow cylinder to intact chalk cores. Methods used to achieve a mineralogic map are:
Energies, May 22, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Minerals, Mar 15, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Energy & Fuels, Apr 20, 2023
Energies, Jun 1, 2022
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Energies
Analyses of fine-grained rocks like shales, cherts, and specifically chalk are challenging with r... more Analyses of fine-grained rocks like shales, cherts, and specifically chalk are challenging with regards to spatial resolution. We propose a “toolbox” to understand mineralogical alteration in chalk, especially those induced by non-equilibrium fluids or polymers and silicates during production of hydrocarbons. These data are fundamental in experiments related to improved/enhanced oil recovery (IOR/EOR) research with the aim to increase hydrocarbon production in a sustainable and environmentally friendly process. The ‘toolbox’ methods analyse rock–fluid or polymer–rock interaction and can be applied to any fine-grained rock type. In our ‘toolbox’, we include methods for routine analysis and evaluate the economic side of the usage together with the complexity of application and the velocity of data acquisition. These methods are routine methods for identification and imaging of components at the same time by chemical or crystallographic means and here applied to petroleum geology. The ...
Energies
This experiment was designed to study the water-weakening effect of artificially fractured chalk ... more This experiment was designed to study the water-weakening effect of artificially fractured chalk caused by the injection of different compositions of brines under reservoir conditions replicating giant hydrocarbon reservoirs at the Norwegian Continental Shelf (NCS). NaCl, synthetic seawater (SSW), and MgCl2, with same ionic strength, were used to flood triaxial cell tests for approximately two months. The chalk cores used in this experiment originate from the Mons basin, close to Obourg, Belgium (Saint Vast Formation, Upper Cretaceous). Three artificially fractured chalk cores had a drilled central hole parallel to the flooding direction to imitate fractured chalk with an aperture of 2.25 (±0.05) mm. Two additional unfractured cores from the same sample set were tested for comparison. The unfractured samples exposed a more rapid onset of the water-weakening effect than the artificially fractured samples, when surface active ions such as Ca2+, Mg2+ and SO42− were introduced. This ins...
Minerals, 2022
Chalk is a very fine-grained carbonate and can accommodate high porosity which is a key character... more Chalk is a very fine-grained carbonate and can accommodate high porosity which is a key characteristic for high-quality hydrocarbon reservoirs. A standard procedure within Improved Oil Recovery (IOR) is seawater-injection which repressurizes the reservoir pore pressure. Long-term seawater-injection will influence mineralogical processes as dissolution and precipitation of secondary minerals. These secondary minerals (<1 micrometer) precipitate during flooding experiments mimicking reservoir conditions. Due to their small sizes, analysis from traditional scanning electron microscopy combined with energy dispersive X-ray spectroscopy is not conclusive because of insufficient spatial resolution and detection limit. Therefore, chalk was analyzed with high-resolution imaging by helium ion microscopy (HIM) combined with secondary ion mass spectrometry (SIMS) for the first time. Our aim was to identify mineral phases at sub-micrometer scale and identify locations of brine–rock interacti...