The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform

Kenter J. A. M. - One of the best experts on this subject based on the ideXlab platform.

  • Diagenetic Evolution of Selected Parasequences Across A Carbonate Platform: Late Paleozoic, Tengiz Reservoir, Kazakhstan
    'Society for Sedimentary Geology', 1
    Co-Authors: Dickson J. A. D., Kenter J. A. M.
    Abstract:

    Abstract: Predicting the diagenetic modification of reservoir quality in carbonate fields is poorly understood but of paramount importance to reservoir characterization. The diagenetic processes and current pore system are reported for two parasequences from the platform center to the margin of the Tengiz reservoir (\~ 16 km); the late Visean (Lvis13 cbs 900) and Bashkirian (Bash2.5 MSF 350) parasequences are separated by 8 million years. Syndepositional fibrous cement (\textgreater 10% rock volume) and aragonite skeletal molds developed in both parasequences. On subaerial exposure, brown soil-related calcite, and meniscus and pendant cements were emplaced in both parasequences. The application of CL petrography to these rocks for the first time has revealed the depositional components and early marine components are altered developing a mottled pattern implying that their original chemistry is not preserved. The principal calcite cement shows a complex growth pattern by CL that is unreported from any other calcite cement. CL is also used to divide the main cement into stage 1, nonluminescent, and stage 2, orange to brown luminescent, calcite. Stage 1 calcite shows vadose meniscus and pendant fabrics followed by uniform phreatic euhedral terminations. Stage 1 cement is patchily distributed at a millimeter scale; 28% to 40% in the Visean and 0.5% to 22% in Bashkirian grainstones. Stage 1 cement is more abundant at the center of the platform in the late Visean than at its margin. Abundant stage 1 calcite creates a framework that prevents later compaction preserving a high porosity at the center of the platform. This sweet spot is reinforced by the deposition of late-stage bitumen cement that occupies 8% rock volume at the margin of the platform but is almost absent at its center. Stage 1 δ13C values (-2.4‰ to +1.7‰) are derived by dissolution of host rock, and their δ18O values (-6.3‰ to -3.7‰) are compatible with precipitation from meteoric or mixed marine-meteoric water. Depositional micrite and micritic grains are transformed by dissolution–precipitation processes into porous microrhombic calcite not by Ostwald ripening. Microrhombic calcite is ubiquitous in the Tengiz icehouse, dispelling the myth that this fabric is restricted to greenhouse epochs. At \~ 300 million years before significant burial the study grainstones were patchily cemented and dissolved to reach peak porosity; their transformed texture set up flow paths that controlled the distribution of later diagenetic products. Reservoir compartmentalization did not occur through extensive hardground formation at this time as occurs in some greenhouse sequences, but ash bands at parasequence boundaries were turned into tonsteins and wackestones were compacted perhaps sufficiently to influence vertical flow. CL examination of stage 2 calcite that adds 0.5% to 16% to rock volume reveals that its precipitation was episodic and switched sites as the pore network became blocked through precipitation and compaction and was opened by new fractures. A change from acute to Equant habit occurred during stage 2 precipitation, causing the change from fibrous to Equant Crystal fabric. The δ18OPDB values of stage 2 calcite (-3‰ to -9‰) are linked to precipitation from an 18O-enriched fluid that evolved to \~ +6‰ SMOW at temperatures of 60°C to 120°C, using the equation of Kim and O'Neil (1997). Many open macropores are lined with small cement Crystals that CL shows have all stages of growth present and are terminated by euhedral surfaces. These macropores are only partly filled because of cement inhibition, not because they were dissolved during burial, as was previously claimed. Late-stage dissolution did create some macropores and rounded micrite Crystals, but its effect on overall platform porosity is small. The CL examination of Tengiz platform calcite cement has recognized many diagenetic events that cannot be recognized without CL. The new Tengiz diagenetic textures recognized here are probably present in other carbonate platforms, especially those from icehouse epo

Jeroen A. M. Kenter - One of the best experts on this subject based on the ideXlab platform.

  • Diagenetic Evolution of Selected Parasequences Across A Carbonate Platform: Late Paleozoic, Tengiz Reservoir, Kazakhstan
    Journal of Sedimentary Research, 2014
    Co-Authors: J A D Dickson, Jeroen A. M. Kenter
    Abstract:

    Abstract Predicting the diagenetic modification of reservoir quality in carbonate fields is poorly understood but of paramount importance to reservoir characterization. The diagenetic processes and current pore system are reported for two parasequences from the platform center to the margin of the Tengiz reservoir (∼ 16 km); the late Visean (Lvis13 cbs 900) and Bashkirian (Bash2.5 MSF 350) parasequences are separated by 8 million years. Syndepositional fibrous cement (> 10% rock volume) and aragonite skeletal molds developed in both parasequences. On subaerial exposure, brown soil-related calcite, and meniscus and pendant cements were emplaced in both parasequences. The application of CL petrography to these rocks for the first time has revealed the depositional components and early marine components are altered developing a mottled pattern implying that their original chemistry is not preserved. The principal calcite cement shows a complex growth pattern by CL that is unreported from any other calcite cement. CL is also used to divide the main cement into stage 1, nonluminescent, and stage 2, orange to brown luminescent, calcite. Stage 1 calcite shows vadose meniscus and pendant fabrics followed by uniform phreatic euhedral terminations. Stage 1 cement is patchily distributed at a millimeter scale; 28% to 40% in the Visean and 0.5% to 22% in Bashkirian grainstones. Stage 1 cement is more abundant at the center of the platform in the late Visean than at its margin. Abundant stage 1 calcite creates a framework that prevents later compaction preserving a high porosity at the center of the platform. This sweet spot is reinforced by the deposition of late-stage bitumen cement that occupies 8% rock volume at the margin of the platform but is almost absent at its center. Stage 1 δ13C values (−2.4‰ to +1.7‰) are derived by dissolution of host rock, and their δ18O values (−6.3‰ to −3.7‰) are compatible with precipitation from meteoric or mixed marine-meteoric water. Depositional micrite and micritic grains are transformed by dissolution–precipitation processes into porous microrhombic calcite not by Ostwald ripening. Microrhombic calcite is ubiquitous in the Tengiz icehouse, dispelling the myth that this fabric is restricted to greenhouse epochs. At ∼ 300 million years before significant burial the study grainstones were patchily cemented and dissolved to reach peak porosity; their transformed texture set up flow paths that controlled the distribution of later diagenetic products. Reservoir compartmentalization did not occur through extensive hardground formation at this time as occurs in some greenhouse sequences, but ash bands at parasequence boundaries were turned into tonsteins and wackestones were compacted perhaps sufficiently to influence vertical flow. CL examination of stage 2 calcite that adds 0.5% to 16% to rock volume reveals that its precipitation was episodic and switched sites as the pore network became blocked through precipitation and compaction and was opened by new fractures. A change from acute to Equant habit occurred during stage 2 precipitation, causing the change from fibrous to Equant Crystal fabric. The δ18OPDB values of stage 2 calcite (−3‰ to −9‰) are linked to precipitation from an 18O-enriched fluid that evolved to ∼ +6‰ SMOW at temperatures of 60°C to 120°C, using the equation of Kim and O'Neil (1997). Many open macropores are lined with small cement Crystals that CL shows have all stages of growth present and are terminated by euhedral surfaces. These macropores are only partly filled because of cement inhibition, not because they were dissolved during burial, as was previously claimed. Late-stage dissolution did create some macropores and rounded micrite Crystals, but its effect on overall platform porosity is small. The CL examination of Tengiz platform calcite cement has recognized many diagenetic events that cannot be recognized without CL. The new Tengiz diagenetic textures recognized here are probably present in other carbonate platforms, especially those from icehouse epochs.

Dickson J. A. D. - One of the best experts on this subject based on the ideXlab platform.

  • Diagenetic Evolution of Selected Parasequences Across A Carbonate Platform: Late Paleozoic, Tengiz Reservoir, Kazakhstan
    'Society for Sedimentary Geology', 1
    Co-Authors: Dickson J. A. D., Kenter J. A. M.
    Abstract:

    Abstract: Predicting the diagenetic modification of reservoir quality in carbonate fields is poorly understood but of paramount importance to reservoir characterization. The diagenetic processes and current pore system are reported for two parasequences from the platform center to the margin of the Tengiz reservoir (\~ 16 km); the late Visean (Lvis13 cbs 900) and Bashkirian (Bash2.5 MSF 350) parasequences are separated by 8 million years. Syndepositional fibrous cement (\textgreater 10% rock volume) and aragonite skeletal molds developed in both parasequences. On subaerial exposure, brown soil-related calcite, and meniscus and pendant cements were emplaced in both parasequences. The application of CL petrography to these rocks for the first time has revealed the depositional components and early marine components are altered developing a mottled pattern implying that their original chemistry is not preserved. The principal calcite cement shows a complex growth pattern by CL that is unreported from any other calcite cement. CL is also used to divide the main cement into stage 1, nonluminescent, and stage 2, orange to brown luminescent, calcite. Stage 1 calcite shows vadose meniscus and pendant fabrics followed by uniform phreatic euhedral terminations. Stage 1 cement is patchily distributed at a millimeter scale; 28% to 40% in the Visean and 0.5% to 22% in Bashkirian grainstones. Stage 1 cement is more abundant at the center of the platform in the late Visean than at its margin. Abundant stage 1 calcite creates a framework that prevents later compaction preserving a high porosity at the center of the platform. This sweet spot is reinforced by the deposition of late-stage bitumen cement that occupies 8% rock volume at the margin of the platform but is almost absent at its center. Stage 1 δ13C values (-2.4‰ to +1.7‰) are derived by dissolution of host rock, and their δ18O values (-6.3‰ to -3.7‰) are compatible with precipitation from meteoric or mixed marine-meteoric water. Depositional micrite and micritic grains are transformed by dissolution–precipitation processes into porous microrhombic calcite not by Ostwald ripening. Microrhombic calcite is ubiquitous in the Tengiz icehouse, dispelling the myth that this fabric is restricted to greenhouse epochs. At \~ 300 million years before significant burial the study grainstones were patchily cemented and dissolved to reach peak porosity; their transformed texture set up flow paths that controlled the distribution of later diagenetic products. Reservoir compartmentalization did not occur through extensive hardground formation at this time as occurs in some greenhouse sequences, but ash bands at parasequence boundaries were turned into tonsteins and wackestones were compacted perhaps sufficiently to influence vertical flow. CL examination of stage 2 calcite that adds 0.5% to 16% to rock volume reveals that its precipitation was episodic and switched sites as the pore network became blocked through precipitation and compaction and was opened by new fractures. A change from acute to Equant habit occurred during stage 2 precipitation, causing the change from fibrous to Equant Crystal fabric. The δ18OPDB values of stage 2 calcite (-3‰ to -9‰) are linked to precipitation from an 18O-enriched fluid that evolved to \~ +6‰ SMOW at temperatures of 60°C to 120°C, using the equation of Kim and O'Neil (1997). Many open macropores are lined with small cement Crystals that CL shows have all stages of growth present and are terminated by euhedral surfaces. These macropores are only partly filled because of cement inhibition, not because they were dissolved during burial, as was previously claimed. Late-stage dissolution did create some macropores and rounded micrite Crystals, but its effect on overall platform porosity is small. The CL examination of Tengiz platform calcite cement has recognized many diagenetic events that cannot be recognized without CL. The new Tengiz diagenetic textures recognized here are probably present in other carbonate platforms, especially those from icehouse epo

J A D Dickson - One of the best experts on this subject based on the ideXlab platform.

  • Diagenetic Evolution of Selected Parasequences Across A Carbonate Platform: Late Paleozoic, Tengiz Reservoir, Kazakhstan
    Journal of Sedimentary Research, 2014
    Co-Authors: J A D Dickson, Jeroen A. M. Kenter
    Abstract:

    Abstract Predicting the diagenetic modification of reservoir quality in carbonate fields is poorly understood but of paramount importance to reservoir characterization. The diagenetic processes and current pore system are reported for two parasequences from the platform center to the margin of the Tengiz reservoir (∼ 16 km); the late Visean (Lvis13 cbs 900) and Bashkirian (Bash2.5 MSF 350) parasequences are separated by 8 million years. Syndepositional fibrous cement (> 10% rock volume) and aragonite skeletal molds developed in both parasequences. On subaerial exposure, brown soil-related calcite, and meniscus and pendant cements were emplaced in both parasequences. The application of CL petrography to these rocks for the first time has revealed the depositional components and early marine components are altered developing a mottled pattern implying that their original chemistry is not preserved. The principal calcite cement shows a complex growth pattern by CL that is unreported from any other calcite cement. CL is also used to divide the main cement into stage 1, nonluminescent, and stage 2, orange to brown luminescent, calcite. Stage 1 calcite shows vadose meniscus and pendant fabrics followed by uniform phreatic euhedral terminations. Stage 1 cement is patchily distributed at a millimeter scale; 28% to 40% in the Visean and 0.5% to 22% in Bashkirian grainstones. Stage 1 cement is more abundant at the center of the platform in the late Visean than at its margin. Abundant stage 1 calcite creates a framework that prevents later compaction preserving a high porosity at the center of the platform. This sweet spot is reinforced by the deposition of late-stage bitumen cement that occupies 8% rock volume at the margin of the platform but is almost absent at its center. Stage 1 δ13C values (−2.4‰ to +1.7‰) are derived by dissolution of host rock, and their δ18O values (−6.3‰ to −3.7‰) are compatible with precipitation from meteoric or mixed marine-meteoric water. Depositional micrite and micritic grains are transformed by dissolution–precipitation processes into porous microrhombic calcite not by Ostwald ripening. Microrhombic calcite is ubiquitous in the Tengiz icehouse, dispelling the myth that this fabric is restricted to greenhouse epochs. At ∼ 300 million years before significant burial the study grainstones were patchily cemented and dissolved to reach peak porosity; their transformed texture set up flow paths that controlled the distribution of later diagenetic products. Reservoir compartmentalization did not occur through extensive hardground formation at this time as occurs in some greenhouse sequences, but ash bands at parasequence boundaries were turned into tonsteins and wackestones were compacted perhaps sufficiently to influence vertical flow. CL examination of stage 2 calcite that adds 0.5% to 16% to rock volume reveals that its precipitation was episodic and switched sites as the pore network became blocked through precipitation and compaction and was opened by new fractures. A change from acute to Equant habit occurred during stage 2 precipitation, causing the change from fibrous to Equant Crystal fabric. The δ18OPDB values of stage 2 calcite (−3‰ to −9‰) are linked to precipitation from an 18O-enriched fluid that evolved to ∼ +6‰ SMOW at temperatures of 60°C to 120°C, using the equation of Kim and O'Neil (1997). Many open macropores are lined with small cement Crystals that CL shows have all stages of growth present and are terminated by euhedral surfaces. These macropores are only partly filled because of cement inhibition, not because they were dissolved during burial, as was previously claimed. Late-stage dissolution did create some macropores and rounded micrite Crystals, but its effect on overall platform porosity is small. The CL examination of Tengiz platform calcite cement has recognized many diagenetic events that cannot be recognized without CL. The new Tengiz diagenetic textures recognized here are probably present in other carbonate platforms, especially those from icehouse epochs.

Kevin J. Roberts - One of the best experts on this subject based on the ideXlab platform.

  • Surface Adsorbed Templates for Directing the Crystal Growth of Entacapone as Monitored Using Process Analytical Techniques
    Crystal Growth & Design, 2013
    Co-Authors: Ana Kwokal, Dražen Čavužić, Kevin J. Roberts
    Abstract:

    Crystallization of entacapone (E-2-cyano-N,N-diethyl-3-(3,4-dihydroxy-5-nitrophenyl) propenamide) in acetone solution at the 500 mL scale using a self-assembled layer of the host material on Au(111) as a seeding template was studied and monitored using attenuated total reflectance (ATR)-UV-vis spectroscopy and focused beam reflectance measurement (FBRM). The data reveal that the template promotes Crystal growth at lower supersaturations and at an increased rate when compared to experiments carried out without the template. Crystals prepared using the template are also found to have superior properties compared to Crystals produced without the template. Notably, use of the template produces Crystals with a much narrower size distribution, greatly increased perfection and a more Equant Crystal morphology. These observations are consistent with the template providing a sympathetic surface for the promotion of Crystallization through an analogous mechanism to that associated with conventional seeding, but wit...

  • Surface Adsorbed Templates for Directing the Crystal Growth of Entacapone as Monitored Using Process Analytical Techniques
    2013
    Co-Authors: Ana Kwokal, Dražen Čavužić, Kevin J. Roberts
    Abstract:

    Crystallization of entacapone (E-2-cyano-N,N-diethyl-3-(3,4-dihydroxy-5-nitrophenyl) propenamide) in acetone solution at the 500 mL scale using a self-assembled layer of the host material on Au(111) as a seeding template was studied and monitored using attenuated total reflectance (ATR)-UV-vis spectroscopy and focused beam reflectance measurement (FBRM). The data reveal that the template promotes Crystal growth at lower supersaturations and at an increased rate when compared to experiments carried out without the template. Crystals prepared using the template are also found to have superior properties compared to Crystals produced without the template. Notably, use of the template produces Crystals with a much narrower size distribution, greatly increased perfection and a more Equant Crystal morphology. These observations are consistent with the template providing a sympathetic surface for the promotion of Crystallization through an analogous mechanism to that associated with conventional seeding, but with the added advantage of conferring a well-ordered, easily reproducible and more robust process