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AAPG Bulletin, 2004
... Eugene received his MS degree in geological oceanography from Old Dominion University, and a ... more ... Eugene received his MS degree in geological oceanography from Old Dominion University, and a BS degree in geology from Edinboro University of ... in subregional areas where three-dimensional (3-D) seismic or dense two-dimensional (2-D) grids are available (Tudoran et al ...
Due to the character of the original source materials and the nature of batch digitization, quali... more Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references.Issued also on microfiche from Lange Micrographics.Cores, logs, and 3D seismic data from Maljamar field (Lea County, southeast New Mexico) were examined in this study and used to construct a detailed sequence stratigraphic framework. Upper San Andres strata are divided into three high-frequency sequences (HFSs). The "maximum flooding intervals" of these HFSs consist of stacked and amalgamated meter-scale cycles which contain mostly subtidal carbonate facies (reservoir facies). In contrast, late highstand to early transgressive systems tracts ("Minimum accommodation intervals") contain cycles that are dominated by non-reservoir peritidal carbonate facies. "Maximum flooding intervals" of individual HFSs therefore comprise the primary flow units. Diagenetic overprinting of primary depositional fabrics, however, has complicated this picture and resulted in extremely complex permeability distributions. Two scales of meteoric diagenesis affected upper San Andres strata at Maljamar field: 1)Short-term (cycle-scale) subaerial exposure events resulted in local porosity inversion (interparticle to moldic) and variable degrees of cementation/dissolution of carbonate sand-shoal deposits.) Long-term subaerial exposure events related to HFS boundaries resulted in locally extensive dissolution and collapse of upper San Andres strata. Cavernous porosity was later plugged with massive anhydrite, resulting in the degradation of reservoir quality. In the overlying Grayburg Formation, cycles consist of mixed sandstone and shallowwater carbonate facies. In the study area, contacts between massive, quartzose sandstones and underlying shallow marine carbonate facies are typically gradational, suggesting that sandstones along the middle Grayburg platform were deposited during high-frequency base-level falls. Massive sandstones are interpreted as eolian sand sheet (erg margin) deposits. Petrographic evidence for an eolian origin of Grayburg sandstones includes the virtual lack of textural variation between sand grains, early evaporate cements, and rare occurrence of low-angle ripple laminae, interpreted as wind-ripple laminae. The interpretation of Grayburg sandstones as dominantly eolian sediments that were deposited during high-frequency base-level falls and lowstands provides an explanation for)the poorly developed cycle stacking patterns that are typical of mixed sandstone-carbonate strata of the Grayburg Formation-nation. Siliciclastic facies largely accumulated above marine base level, effectively filling "negative platform accommodation," and resulting in amalgamation-nation of sandstone cycles during times of reduced long-term accommodation. Because sandstone facies are interpreted as the most "regressive" facies within the Grayburg Formation, vertical trends in the dominance of nonmarine sandstone versus shallow-marine carbonate facies (visible in gamma-ray logs) can be used to constrain detailed sequence stratigraphic and lithologic correlations
AAPG Bulletin, 2012
Evaluations of porosity relevant to hydrocarbon storage capacity in kerogen-rich mudrocks (i.e., ... more Evaluations of porosity relevant to hydrocarbon storage capacity in kerogen-rich mudrocks (i.e., source rocks) have thus far been plagued with ambiguity, in large part because conventional core and petrophysical techniques were not designed for this rock type. The growing recognition of an intraparticle organic nanopore system that is related to thermal maturity is beginning to clarify this ambiguity. This mode of porosity likely evolved with the thermal transformation of labile kerogen and probably neither depends nor interacts (except perhaps chemically) with previously assumed "matrix" or "mineral" porosity that is dominated by bound water, and that may be largely irrelevant to hydrocarbon storage capacity in these rocks. To address this newly recognized and important nonmatrix kerogen pore system, that is arguably the dominant hydrocarbon storage and mobility network in these rocks, we introduce a relatively simple kinetic model that describes porosity development within kerogen as a function of thermal maturation. Kerogen porosity development is estimated within the upper Albian Mowry Shale in the Powder River Basin of Wyoming to illustrate the approach. Relevant storage capacity is considered to have evolved with thermal decomposition of organic matter during catagenesis, where we estimate that kerogen porosity does not typically exceed 3% of bulk rock volume.
SEG Technical Program Expanded Abstracts 2008, 2008
AAPG Bulletin, 2004
... Eugene received his MS degree in geological oceanography from Old Dominion University, and a ... more ... Eugene received his MS degree in geological oceanography from Old Dominion University, and a BS degree in geology from Edinboro University of ... in subregional areas where three-dimensional (3-D) seismic or dense two-dimensional (2-D) grids are available (Tudoran et al ...
Due to the character of the original source materials and the nature of batch digitization, quali... more Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item.Includes bibliographical references.Issued also on microfiche from Lange Micrographics.Cores, logs, and 3D seismic data from Maljamar field (Lea County, southeast New Mexico) were examined in this study and used to construct a detailed sequence stratigraphic framework. Upper San Andres strata are divided into three high-frequency sequences (HFSs). The "maximum flooding intervals" of these HFSs consist of stacked and amalgamated meter-scale cycles which contain mostly subtidal carbonate facies (reservoir facies). In contrast, late highstand to early transgressive systems tracts ("Minimum accommodation intervals") contain cycles that are dominated by non-reservoir peritidal carbonate facies. "Maximum flooding intervals" of individual HFSs therefore comprise the primary flow units. Diagenetic overprinting of primary depositional fabrics, however, has complicated this picture and resulted in extremely complex permeability distributions. Two scales of meteoric diagenesis affected upper San Andres strata at Maljamar field: 1)Short-term (cycle-scale) subaerial exposure events resulted in local porosity inversion (interparticle to moldic) and variable degrees of cementation/dissolution of carbonate sand-shoal deposits.) Long-term subaerial exposure events related to HFS boundaries resulted in locally extensive dissolution and collapse of upper San Andres strata. Cavernous porosity was later plugged with massive anhydrite, resulting in the degradation of reservoir quality. In the overlying Grayburg Formation, cycles consist of mixed sandstone and shallowwater carbonate facies. In the study area, contacts between massive, quartzose sandstones and underlying shallow marine carbonate facies are typically gradational, suggesting that sandstones along the middle Grayburg platform were deposited during high-frequency base-level falls. Massive sandstones are interpreted as eolian sand sheet (erg margin) deposits. Petrographic evidence for an eolian origin of Grayburg sandstones includes the virtual lack of textural variation between sand grains, early evaporate cements, and rare occurrence of low-angle ripple laminae, interpreted as wind-ripple laminae. The interpretation of Grayburg sandstones as dominantly eolian sediments that were deposited during high-frequency base-level falls and lowstands provides an explanation for)the poorly developed cycle stacking patterns that are typical of mixed sandstone-carbonate strata of the Grayburg Formation-nation. Siliciclastic facies largely accumulated above marine base level, effectively filling "negative platform accommodation," and resulting in amalgamation-nation of sandstone cycles during times of reduced long-term accommodation. Because sandstone facies are interpreted as the most "regressive" facies within the Grayburg Formation, vertical trends in the dominance of nonmarine sandstone versus shallow-marine carbonate facies (visible in gamma-ray logs) can be used to constrain detailed sequence stratigraphic and lithologic correlations
AAPG Bulletin, 2012
Evaluations of porosity relevant to hydrocarbon storage capacity in kerogen-rich mudrocks (i.e., ... more Evaluations of porosity relevant to hydrocarbon storage capacity in kerogen-rich mudrocks (i.e., source rocks) have thus far been plagued with ambiguity, in large part because conventional core and petrophysical techniques were not designed for this rock type. The growing recognition of an intraparticle organic nanopore system that is related to thermal maturity is beginning to clarify this ambiguity. This mode of porosity likely evolved with the thermal transformation of labile kerogen and probably neither depends nor interacts (except perhaps chemically) with previously assumed "matrix" or "mineral" porosity that is dominated by bound water, and that may be largely irrelevant to hydrocarbon storage capacity in these rocks. To address this newly recognized and important nonmatrix kerogen pore system, that is arguably the dominant hydrocarbon storage and mobility network in these rocks, we introduce a relatively simple kinetic model that describes porosity development within kerogen as a function of thermal maturation. Kerogen porosity development is estimated within the upper Albian Mowry Shale in the Powder River Basin of Wyoming to illustrate the approach. Relevant storage capacity is considered to have evolved with thermal decomposition of organic matter during catagenesis, where we estimate that kerogen porosity does not typically exceed 3% of bulk rock volume.
SEG Technical Program Expanded Abstracts 2008, 2008