Comparing The Depositional Environment Of The Upper Smackover Formation In Southwestern Clarke County, Mississippi And Brooklyn/ Little Cedar Creek Field, Alabama

This research evaluated the depositional settings of the upper Smackover formation in southwestern Clarke County (scc), Mississippi and compared its facies to those of the Brooklyn and little cedar creek fields (bf/lcc) in Conecuh and Escambia Counties, Alabama. The Smackover formation has been a prolific oil producing formation in the Gulf of Mexico since its discovery in Union County, Arkansas in 1937. The discovery of the lcc in 1994 and the bf in 2007 has generated additional interest in the Smackover. The bf/ lcc occur near the updip limit of the upper Jurassic (Oxfordian) Smackover formation. These fields produce from oolitic/ oolmoldic stratigraphically trapped reservoirs in the upper Smackover formation. In scc, the Smackover extends farther updip than in the bf/lcc. Scc also has several small oil fields that have produced from the Smackover formation since 1976. This research used resistivity well logs and core analyses of scc fields and selected four fields with the most oolites and therefore, the highest potential for similarity to production in the bf/lcc. The resistivity logs and core analyses of these four fields were used to construct structure contour maps and cross-sections for each field, illustrating the Smackover facies in the region. Higher resolution resistivity logs and core analyses from the bf/lcc were also used to construct cross sections of that area. Lithofacies and logfacies were defined for the research and used to compare the bf/lcc and scc. Interpretation of the cross sections and maps shothat the bf/lcc and scc have similar depositional settings and also similar lithofacies/depositional sequence. The difference between the study areas are: a lack of mudstones lithofacies in the bf/lcc; differences in thickness of the upper Smackover and; differences in logfacies. The bf/lcc and scc have substantial similarities in their depositional environment and sequence with the east nancy field in scc showing the most similarities to the bf/lcc

Diagenetic controls of reservoir quality in the Mississippian Wayne Beds in the Williston Basin, Bottineau County, North Dakota

The carbonate Wayne beds of the Frobisher-Alida interval (Mississippian Mission Canyon Formation) in the Williston Basin, North Dakota, are capable of producing as much as 400,000 barrels of oil per well at depths of only 3,100 feet. Wayne production is from structural traps in the intertidal packstone-wackestone lithofacies; however, the ultimate recoverable reserves of oil per well is controlled neither by structure, nor by depositional environments. The Wayne beds underwent cementation and micritization in the marine phreatic diagenetic environment. Hypersaline diagenesis caused minor dolomitization and anhydritization. Dissolution and minor cementation occurred in the freshwater vadose zone. Freshwater phreatic diagenesis resulted in mineralogical stabilization and minor cementation. Compaction, pressure solution, dolomite and calcite cementation, and anhydritization occurred in the burial diagenetic environment. Depleted o13C in the carbonates immediately below the pre-Mesozoic unconformity surface suggests that vugular and solution-enlarged porosity formed in the freshwater vadose zone. Beneath paleoislands, mineralogical stabilization in the freshwater phreatic zone prevented later porosity reduction by compaction or cementation. On the flanks of the paleoislands and in paleolows, porosity was occluded by dolomite and calcite cement. The dolomite cement has 6180 consistent with a burial diagenesis origin. Permeability reduction by pore-bridging anhydrite cements post-date the pore-occluding dolomites. Wayne beds contain much less pore-bridging anhydrite beneath paleohighs where the overlying Glenburn evaporites were removed due to erosion than beneath paleolows where the Glenburn is still present. Sulfur stable-isotope data suggest that the sulfur in these pore-bridging anhydrites originated in the Glenburn evaporites. The amount of Wayne oil production from structural traps in the study area is controlled by diagenetic rather than depositional features. Porosity was occluded by burial dolomite and calcite cements in paleolows. Permeability was reduced by burial anhydrite cements in localities where the Glenburn has not been eroded. Thus, the best production within a field comes from those portions of the reservoir which were once beneath islands and/or eroded highs

Structural Controls and Depositional Environments of the Glen Rose Subgroup in Pelahatchie Field in Rankin County, Mississippi

Following Lion Oil’s drilling of the Sowell #1, Lower Cretaceous step-out drilling in Pelahatchie Field has led to the establishment of Mooringsport, Paluxy, Rodessa, Sligo, and Hosston oil and gas condensate production along the flanks and crest of a salt feature within Rankin County, Mississippi. Exploration of salt features has been intermittent throughout Mississippi, but has shifted from targeting pay zones along the crests of domal and piercement salt features in the 1940s, to targeting reserves along the flanks of these features in the 1970s. The dominant structural feature in Pelahatchie Field is an elongate north-south-trending salt ridge. Results of this study suggest that combination traps predominate. The Glen Rose Subgroup in southern Rankin County transitions from upper shoreface to the south of the study area, to estuarine tidal flats in a more restrictive environment within Pelahatchie Field. The discovery of a channel within the lower Rodessa Formation records a short period of fluvial deposition. A more clear definition of paleo-depositional environments in association with structural and stratigraphic controls on production are important to the continued oil and gas exploration of salt dome plays in the Mississippi Interior Salt Basin

Controls on development and diversity of Early Archean stromatolites

The ≈3,450-million-year-old Strelley Pool Formation in Western Australia contains a reef-like assembly of laminated sedimentary accretion structures (stromatolites) that have macroscale characteristics suggestive of biological influence. However, direct microscale evidence of biology—namely, organic microbial remains or biosedimentary fabrics—has to date eluded discovery in the extensively-recrystallized rocks. Recently-identified outcrops with relatively good textural preservation record microscale evidence of primary sedimentary processes, including some that indicate probable microbial mat formation. Furthermore, we find relict fabrics and organic layers that covary with stromatolite morphology, linking morphologic diversity to changes in sedimentation, seafloor mineral precipitation, and inferred microbial mat development. Thus, the most direct and compelling signatures of life in the Strelley Pool Formation are those observed at the microscopic scale. By examining spatiotemporal changes in microscale characteristics it is possible not only to recognize the presence of probable microbial mats during stromatolite development, but also to infer aspects of the biological inputs to stromatolite morphogenesis. The persistence of an inferred biological signal through changing environmental circumstances and stromatolite types indicates that benthic microbial populations adapted to shifting environmental conditions in early oceans

Late Miocene to early Pliocene stratigraphic record in northern Taranaki Basin: Condensed sedimentation ahead of Northern Graben extension and progradation of the modern continental margin

The middle Pliocene-Pleistocene progradation of the Giant Foresets Formation in Taranaki Basin built up the modern continental margin offshore from western North Island. The late Miocene to early Pliocene interval preceding this progradation was characterised in northern Taranaki Basin by the accumulation of hemipelagic mudstone (Manganui Formation), volcaniclastic sediments (Mohakatino Formation), and marl (Ariki Formation), all at bathyal depths. The Manganui Formation has generally featureless wireline log signatures and moderate to low amplitude seismic reflection characteristics. Mohakatino Formation is characterised by a sharp decrease in the GR log value at its base, a blocky GR log motif reflecting sandstone packets, and erratic resistivity logs. Seismic profiles show bold laterally continuous reflectors. The Ariki Formation has a distinctive barrel-shaped to blocky GR log motif. This signature is mirrored by the SP log and often by an increase in resistivity values through this interval. The Ariki Formation comprises (calcareous) marl made up of abundant planktic foraminifera, is 109 m thick in Ariki-1, and accumulated over parts of the Western Stable Platform and beneath the fill of the Northern Graben. It indicates condensed sedimentation reflecting the distance of the northern region from the contemporary continental margin to the south

Regional Geology of the Low-Permeability Gas-Bearing Cleveland Formation, Western Anadarko Basin, Texas Panhandle: Lithologic and Depositional Facies, Structure, and Sequence Stratigraphy

The Upper Pennsylvanian (lower Missourian) Cleveland Formation produces gas from low-permeability ("tight") sandstone reservoirs in the western Anadarko Basin of the northeastern Texas Panhandle. In this six-county region, these reservoirs had produced more than 412 Bcf of natural gas through December 31, 1989. Because of their typically low permeability, the Cleveland sandstones require acidizing and hydraulic fracture treatment to produce gas at economic rates. Since 1982, the Gas Research Institute has supported geological investigations throughout the United States to develop the scientific and technological knowledge for producing from low-permeability, gas-bearing sandstones. As part of this program and the GRI Tight Gas Sands project, the Bureau of Economic Geology has been conducting research on low-permeability sandstones in the Cleveland Formation and on several other sandstone units of similar character in Texas and Wyoming. This effort is part of a broader program to increase the understanding and ultimate utilization of gas resources in these low-permeability formations through regional and field-specific geology, formation evaluation, and reservoir engineering. This report summarizes findings on the regional geology, depositional setting, sequence stratigraphy, and petrology of the Cleveland Formation. Geological research on the Cleveland began with an effort to choose a formation in which to drill Staged Field Experiment (SFE) well number 4, the latest in a series of SFE wells drilled since 1986 to conduct geological and engineering research on low-permeability gas reservoirs. Although the Cleveland Formation was not chosen for SFE No. 4, investigation of this low-permeability, gas-bearing sandstone continued with the drilling of cooperative wells in the unit. Because the Cleveland Formation contains an estimated 38 Tcf of gas in place, development of advanced technology and understanding that can be applied to this and other tight gas formations will have a positive impact on gas supply by improving gas recovery and lowering completion costs.Bureau of Economic Geolog

Rift to drift transition in the southwest Australian deepwater Mentelle Basin

2021 Summer.Includes bibliographical references.The Mentelle Basin is a deepwater polyphase basin located off of the southwest margin of Australia that formed during Late Jurassic and Early Cretaceous breakup of Gondwana. It is underlain by highly extended continental crust and is bordered to the west by less extended crust forming the Naturaliste Plateau, and to the east by the Yalingup Shelf and Perth Basin beneath the continental shelf and coastal plain. The purpose of this study is to characterize the depositional, subsidence, and tectonic histories of the Mentelle Basin during the syn-rift to post-rift transition period. We use seismic reflection data and boreholes drilled by the Deep Sea Drilling Project and International Ocean Discovery Program (IODP) to map three horizons and intermittent volcanic features within this > 134 Ma to 126 Ma period. The youngest horizon mapped was the top of Lithostratigraphic Unit 5 (LSU5) at IODP Site U1513, which corresponds with the lower Aptian age (126 Ma) when rifting on this part of the margin ended and seafloor spreading began between Greater India and Australia west of the Naturaliste Plateau. Also mapped was a reflector encountered at the top of the basalt pile in IODP Hole U1513D at the western edge of the Mentelle Basin. The oldest horizon mapped is the Valanginian Unconformity that lies below this basalt pile and corresponds with breakup and the onset of seafloor spreading on the Perth Abyssal Plain further north. Isochore maps and two depth structure maps generated from these horizons illustrate the subsidence history and structural and magmatic evolution of the Mentelle Basin during breakup. Syn-rift magmatism in the Mentelle Basin was more widespread than previously thought. While earlier studies deemed the western half of the Mentelle Basin magmatic, the eastern extent of magmatism was unknown. Seismic correlation of the basalt reflector at Site U1513 indicates the Naturaliste Plateau basalts extended eastward to the eastern flank of the Mentelle Basin. Younger flows 2 – 20 km wide and occasional volcanic cones ranging from 0.5 – 2.5 km wide are imaged in the western half of the basin to the toe of the eastern slope. These younger volcanic features were emplaced between the late Valanginian through the start of the Aptian age. Basalt flows and some volcanic features in the basin are interpreted to have been exposed and weathered at or above sea level around the time of emplacement before subsequent burial by a marine transgression. The Mentelle Basin began to subside prior to the Naturaliste Plateau (> 134 Ma) as rifting occurred between India and Australia-Antarctica. Once final breakup occurred and seafloor spreading began west of the Naturaliste Plateau, both the Mentelle Basin and Naturaliste Plateau subsided to bathyal depths beginning around 126 Ma

INTEGRATED GEOLOGIC-ENGINEERING MODEL FOR REEF AND CARBONATE SHOAL RESERVOIRS ASSOCIATED WITH PALEOHIGHS: UPPER JURASSIC SMACKOVER FORMATION, NORTHEASTERN GULF OF MEXICO

The University of Alabama in cooperation with Texas A&M University, McGill University, Longleaf Energy Group, Strago Petroleum Corporation, and Paramount Petroleum Company are undertaking an integrated, interdisciplinary geoscientific and engineering research project. The project is designed to characterize and model reservoir architecture, pore systems and rock-fluid interactions at the pore to field scale in Upper Jurassic Smackover reef and carbonate shoal reservoirs associated with varying degrees of relief on pre-Mesozoic basement paleohighs in the northeastern Gulf of Mexico. The project effort includes the prediction of fluid flow in carbonate reservoirs through reservoir simulation modeling which utilizes geologic reservoir characterization and modeling and the prediction of carbonate reservoir architecture, heterogeneity and quality through seismic imaging. The primary objective of the project is to increase the profitability, producibility and efficiency of recovery of oil from existing and undiscovered Upper Jurassic fields characterized by reef and carbonate shoals associated with pre-Mesozoic basement paleohighs. The principal research effort for Year 2 of the project has been reservoir characterization, 3-D modeling and technology transfer. This effort has included six tasks: (1) the study of rockfluid interactions, (2) petrophysical and engineering characterization, (3) data integration, (4) 3-D geologic modeling, (5) 3-D reservoir simulation and (6) technology transfer. This work was scheduled for completion in Year 2. Overall, the project work is on schedule. Geoscientific reservoir characterization is essentially completed. The architecture, porosity types and heterogeneity of the reef and shoal reservoirs at Appleton and Vocation Fields have been characterized using geological and geophysical data. The study of rock-fluid interactions is near completion. Observations regarding the diagenetic processes influencing pore system development and heterogeneity in these reef and shoal reservoirs have been made. Petrophysical and engineering property characterization has been essentially completed. Porosity and permeability data at Appleton and Vocation Fields have been analyzed, and well performance analysis has been conducted. Data integration is up to date, in that, the geological, geophysical, petrophysical and engineering data collected to date for Appleton and Vocation Fields have been compiled into a fieldwide digital database. 3-D geologic modeling of the structures and reservoirs at Appleton and Vocation Fields has been completed. The model represents an integration of geological, petrophysical and seismic data. 3-D reservoir simulation of the reservoirs at Appleton and Vocation Fields has been completed. The 3-D geologic model served as the framework for the simulations. A technology workshop on reservoir characterization and modeling at Appleton and Vocation Fields was conducted to transfer the results of the project to the petroleum industry