<p> A 6012-foot Monterey Formation succession at Chico Martinez Creek, San Joaquin basin, is characterized at high spatial resolution by spectral gamma-ray data in 2- foot increments, 5-foot lithologic descriptions, and qualitative XRD and FTIR analysis. Based on these data, the 4 Monterey members&ndash;the Gould, Devilwater, McDonald and Antelope shales&ndash;are subdivided into 7 distinctive lithofacies. New paleomagnetic data, combined with industry-provided biostratigraphy establishes a chronostratigraphic framework and allows determination of linear sediment accumulation rates. Condensed sedimentation at the onset of McDonald deposition (~14 Ma) is also observed in correlative members in the Pismo, Santa Maria and Santa Barbara basins. This regional event is associated with eustatic regression from the Mid-Miocene highstand related to formation of the East Antarctic Ice Sheet and ongoing thermotectonic basin subsidence. A surge in linear sediment accumulation rates in the siliceous upper McDonald and Antelope (~10.4 Ma) is attributed to a regional increase in diatom productivity. </p>

Stratigraphy and source rock analyses of the Heath Formation in Fergus, Garfield, Golden Valley, Musselshell, Petroleum, and Rosebud counties, central Montana

<p> Two industry acquired diatomite cores (Sisquoc Formation) from the Orcutt (Newlove 76-RD1) and Casmalia Hills (Stokes A-30804) oil fields were analyzed by core descriptions, laboratory analysis (XRD and SEM), and gamma ray logs. Based on these data, five distinct lithofacies, nine sedimentary features and compositional trends of both cores were established. Newlove 76-RD1 and Stokes A-30804 record an upward-shallowing succession at different depositional positions on the Pliocene paleo-slope of the Santa Maria basin. Stokes A-30804 reflects slope deposition on a lower flank of a paleo-bathymetric high receiving higher detrital influx from inter-ridge troughs. Slope deposition of Newlove 76-RD1 was closer to a paleo-bathymetric high where purer diatomaceous sediments accumulated. Within Stokes A-30804, purer opal-A dominant lithofacies contain the highest oil saturations. The diagenesis and precipitation of opal-CT and abundance of phyllosilicate significantly hinders oil saturation within lithofacies.</p>

<p> Though the Cotton Valley Group is productive in Mississippi, Louisiana, and Texas, little is known about production potential of the Bossier Formation (Lower Cotton Valley Shale) in southwest Mississippi. The Bossier Formation in Jefferson County, Mississippi is an organic-poor, carbonate-rich mudrock with siliciclastic intervals. Examination of cuttings by petrographic and scanning electron microscopy revealed fractures that have been filled by calcite and pore-filling pyrite. Porosity exists within and around pyrite framboids, in unfilled fractures, and within peloid grains. Organic matter is rare in Lower Cotton Valley samples suggesting it is not self-sourcing. Total Organic Carbon (TOC) values are low (0.86-1.1% TOC) compared to the productive Haynesville Shale Formation (2.8% TOC). Porosity of the Lower Cotton Valley Shale is low (2.5-4.2%) compared to productive Haynesville Shale Formations (8-12%). With current technology and gas prices, the Lower Cotton Valley Shale in Jefferson County, Mississippi does not have production potential.</p>

<p> The Middle Devonian Marcellus Shale is a natural gas producing formation that was deposited in the Appalachian foreland basin in what is now eastern North America. An unconformity truncates the Marcellus in southern West Virginia and progressively younger units onlap progressively older units. The zero isopach line that marks the edge of the Marcellus is mapped to reveal the southeastern boundary. A well production analysis is conducted to locate the region of maximum natural gas production. Four lithologic completions intervals in three different well fields are compared. This study shows that the most economically viable drilling is from the Marcellus Shale completion intervals that are less than 30 feet in Chapmanville gas field in western Logan County, West Virginia. Outside of the zero isopach are areas comprised of onlapping featheredges of younger formations that comprise a black shale unit mistakenly identified as &ldquo;Marcellus Shale&rdquo;. These areas produce significantly less gas than the &ldquo;true&rdquo; Marcellus Shale.</p>

<p> Integrated analysis of well and geophysical data can provide detailed geologic interpretation of the subsurface in Osage County, Oklahoma. Systems tracts and depositional system successions can be interpreted at marginal seismic resolution using well log motif with seismic reflector character within a depositional context. Shelf-prism and subaqueous, delta-scale clinoforms of Missourian age observed in 3D seismic were interpreted with greater sequence stratigraphic detail when coupled with wireline well logs. The Late Pennsylvanian Midcontinent Sea was thought to be approximately 150 feet average depth across the southern Midcontinent during the Missourian Stage, and deepen towards the Arkoma and Anadarko Basins to the south. Here we show that the Late Pennsylvanian Midcontinent Sea floor was in water depths greater than 600 feet and sloped to the southeast, toward major, southern basins, during the Missourian Stage in Osage County. Shelf-prism and delta scale clinoforms up to 600 and 300 feet of relief, respectively, were observed in paired seismic and well log cross sections, thickness maps, and structure maps dipping northwest at 052&deg; strike, upon a basin floor dipping southeast at 253&deg; strike. Lithologic and sequence stratigraphic interpretation revealed a mixed carbonate-siliciclastic system comprising of delta, offshore shelf, and carbonate buildup depositional systems of mesothem, 3rd order sequence magnitude. The observed succession included: 1) falling stage to lowstand, sand-prone, subaqueous delta, 2) transgressive to highstand offshore shelf and carbonate bank, and 3) falling stage delta. The depositional sucession demonstrates how carbonate banks related spatially to terrigenous sediment input in northeastern Oklahoma during the Late Pennsylvanian because of glacio-eustasy and possible tectonism.</p><p>

<p> The Tuscaloosa Marine Shale (TMS) in southwest Mississippi and south-central Louisiana has potential to become a prolific source of fossil fuels using hydraulic fracturing technology. The objective of this study is to better understand the sequence and regional stratigraphy, lithology, and character of the TMS. Studying the TMS&rsquo;s lithologic, depositional, and diagenetic properties is essential to maximize potential production. Characterization of the eastern TMS was performed with cuttings from two wells provided by the Mississippi Oil and Gas Board through MDEQ, and two provided by the USGS. Thirty-one petrophysical logs were correlated, to make cross sections and trace sequence stratigraphic intervals within the TMS. Results of the study showed lithologic variability and compaction across the study area, and a sequence stratigraphic correlation of the highstand systems track between the Tuscaloosa and Eagle Ford Groups. This research aims to work toward the greatest potential of the TMS as an unconventional reservoir.</p><p>

<p> Over the past 70 years the Mississippian strata of Northwest Arkansas have been studied in great detail. The study area is located on the escarpment between the Boston Mountains Plateau and the Springfield Plateau where a surface occurrence of Mississippian age rock allows for access to outcrops in close proximity to gas wells that encounter subsurface Mississippian strata. Many outcrops found in Northwest Arkansas expose Lower Mississippian (Kinderhookian-Osagean) strata that represent a full third order transgressive/regressive sequence that is unconformity bounded. These Mississippian outcrops are commonly treated as surface analogs to the Mississippi Lime Play in North Central Oklahoma. This thesis focuses on the analysis of Boone tripolitic chert in the subsurface utilizing wireline data available from selected gas wells within the study area. The primary goal of this project is to determine and quantify the subsurface stratigraphic position of tripolitic chert from wells that cut a complete section of the Boone Formation. 24 of the 27 (89%) wells within the study with bulk density logs penetrated a substantial section of the Boone Formation and confirmed the presence of tripolite through a density value less than 2.1 g/cc. </p><p> Analysis of wireline data from selected wells is used to characterize the Mississippian system with a specific focus on the distribution of tripolitic chert. Correlation of Mississippian gas production to tripolitic chert occurrence along with the correlation of subsurface data with outcrop data are secondary objectives.</p><p>

<p> The informally known &ldquo;Mississippian Limestone&rdquo; stratigraphic interval in north-central Oklahoma, U.S.A. bears no chronostratigraphic markers and has no formally established biostratigraphic framework to date. Conodonts collected from four &ldquo;Mississippian Limestone&rdquo; cores in Logan, Payne, and Lincoln Counties provide the means for better constraining the stratigraphic age of the interval over the area studied. Conodont extraction was conducted by acid digestion of whole-rock samples and heavy liquid density separation after which conodont genera and species types were identified from scanning electron microscopy. Biostratigraphically significant conodonts recovered in combination with chemostratigraphic work by Dupont (2016) and earlier studies by Thornton (1958), Curtis and Chaplin (1959), McDuffie (1959), Rowland (1964), Selk and Ciriacks (1968), and Harris (1975) indicate the &ldquo;Mississippian Limestone&rdquo; ranges from middle Osagean to late Chesterian in age. In general, conodont element recoveries were too low in quantity and too poor of quality for use as biostratigraphic markers. The relatively low recovery and poor preservation quality of the conodont elements are attributed primarily to the elements being reworked soon after deposition by frequent storms on a mid- to outer-ramp environment in a low-latitude carbonate ramp setting. The results of this investigation are most significant in that they help place Mississippian deposition over the area studied within the context of a global Carboniferous stratigraphy. The results also allow for the Mississippian interval in the study area to be more accurately related to time-correlative strata with similar or better age constraint for constructing more temporally meaningful depositional models of the Oklahoma basin.</p><p>