<p> An attempt is made to determine compositional and textural trends in the direction of sediment transport in middle Triassic cross-bedded sandstone samples collected from northeastern British Columbia. Petrographic measurements of textural and compositional properties were made and a multiple regression analysis was performed on 27 samples collected from a particular lithological unit. The general petrographic aspects of middle Triassic sandstones were investigated and are discussed.</p> / Thesis / Master of Science (MSc)

The Columbus Basin, offshore Trinidad, is a mature gas producing basin with a number of major fields now in decline. Focus for infield exploration and production is shifting, with thin bedded sandstones as a secondary pay target. This basin is exceptional as age equivalent analogues to the subsurface reservoirs are exposed along the south east coast of Trinidad at Mayaro Bay (16 – 25 m sections). This research utilizes these outcrops and integrates findings with subsurface core data to present an improved understanding of thin bedded sandstones in three significant areas: 1) depositional setting on a wave dominated delta through description and interpretation of their large scale architecture and facies associations, 2) reservoir quality and connectivity of the facies and microfacies that comprise these heterolithic units through petrography and pore system characterization and 3) pore scale reservoir quality and connectivity through micro CT imaging and 3D modelling of their pore system morphology. Detailed sedimentological analysis has revealed that thin beds are highly interbedded units with thicknesses of 0.1 – 10 cm and have a lenticular geometry. Their lateral extent, controlled by their exposure, varies from 3 to 10s m in some areas. Field sampling and microfacies analysis, revealed five distinct lithofacies types and five microfacies types that make up two principal facies associations (FA): (FA1) axial distal delta front facies and (FA2) lateral distal delta front facies. The reservoir quality poroperm data achieved for the thin sandstones of these two facies associations are consistent with routine core analysis data from basin core and industry assigned values for conventional thicker bedded sandstones, inferring their secondary reservoir potential. Utilizing new techniques such as X-Ray tomography, a high resolution 3D model of the thin sandstone pore systems has been created for qualitative and quantitative reservoir characterization, especially vertical and lateral connectivity within the thin bedded units. This detailed dataset of 3D pore dimensions that can be used as conditioning data for other reservoir models. The observations and conclusions of this research give an insight into the depositional architecture and thin bedded sandstones on a distal delta front and their associated reservoir properties and connectivity mechanisms that facilitate an effective reservoir. These findings may inform and guide future exploration and appraisal, development and production and well completion and configuration programmes for thin bedded reservoirs as explained by the implications and recommendations at the end of this thesis.

Thesis advisor: Noah P. Snyder / River channel morphology in northern New England depends on channel position relative to glacial geomorphology and history. This thesis considers three paraglacial Maine rivers: the West Branch of the Pleasant River (WBPR), a steep inland imposed-form tributary of the Piscataquis River, and the Narraguagus and Sheepscot rivers, two coastal low-gradient rivers. I use a simple model based on the Shields and Manning equations to predict median bed grain size in these recently deglaciated watersheds. The main objectives of this study are to: (1) understand how bedrock controls on the longitudinal profile and sediment inputs impact substrate grain size and channel morphology in the WBPR; (2) apply a model predicting substrate grain size based on digital elevation model (DEM)-derived geometric channel parameters; (3) compare the results from the high gradient WBPR to previously studied low-gradient coastal Maine rivers; and (4) explore the implications of my findings on channel and habitat restoration in paraglacial rivers. I use standard and lidar (light detection and ranging) digital elevation models (DEMs) and spatial analyses to measure channel parameters necessary to predict bed grain size and compare them to field measurements. Predicted bed grain size falls within a factor of two of the field-measured median in ~70% of the study sites. The model performs best in supply-limited alluvial single-thread channel segments with gravel-cobble lag deposit beds, and is less successful in transport-limited depositional segments with relatively fine beds and greater channel variability. Channel segments that are transitional between these two cases (intermediate channel complexity and grain size) are associated with intermediate grain size prediction accuracy. Model failures occur in segments that deviate from the single-thread gravel-bed channel type, and may indicate areas to focus restoration efforts. This study builds on previous research on low-gradient coastal rivers in Maine, and has wide application to future research or restoration projects concerned with sediment mobilization and fluvial ecology. / Thesis (MS) — Boston College, 2011. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Geology and Geophysics.

We introduce a new quantitative approach to improve the petrophysical evaluation of thinly bedded sand-shale sequences that have undergone extensive diagenesis. Formations under analysis consist of carbonate-rich clastic sediments, with pore system heavily reworked by calcite and authigenic clay cementation, giving rise to rocks with high spatial heterogeneity, low porosity, and low permeability. Porosity varies from 2 to 20% and permeability varies from less than 0.001 mD to 200 mD. Diagenesis and thin laminations originate complex magnetic resonance (NMR) T2 distributions exhibiting multimodal distributions. Furthermore, reservoir units produce highly viscous oil, which imposes additional challenges to formation evaluation. Petrophysical evaluation of thinly bedded formations requires accurate estimation of laminar and dispersed shale concentration. We combined Thomas-Stieber’s method, OBMI, and Rt-Scanner measurements to calculate laminar shale concentration. Results indicate that hydrocarbon reserves can be overestimated in the presence of high-resistivity streaks and graded beds, which give rise to electrical anisotropy. To account for electrical anisotropy effects on petrophysical estimations, we classified reservoir rocks based on the cause of electrical anisotropy. Thereafter different interpretation methods were implemented to estimate petrophysical properties for each rock class. We also appraised the advantages and limitations of the high-resolution method for evaluating thinly bedded formations with respect to other petrophysical interpretation methods. Numerical simulations were performed on populated earth-model properties after detecting bed boundaries from resistivity or core images. Earth-model properties were iteratively refined until field and numerically simulated logs reached an acceptable agreement. Results from the high-resolution method remained petrophysically consistent when beds were thicker than 0.25 ft. Numerical simulations of NMR T2 distributions were also performed to reproduce averaging effects of NMR responses in thinly bedded formations, which enabled us to improve the assessment of pore-size distributions, in-situ fluid type, and saturation. Permeability of sand units was estimated via Timur-Coates’ equation by removing the effect of laminar shale on porosity and bulk irreducible volume water. Shoulder-bed corrected logs were input to the calculations. Petrophysical properties obtained with the developed interpretation method honor all the available measurements including conventional well logs, NMR, resistivity images, multi-component induction, and core measurements. The developed interpretation method was successfully tested across four hydrocarbon-saturated intervals selected from multiple wells penetrating a deep turbidite system. Permeability values obtained with the new interpretation method improved the correlation with core measurements by 16% as compared to permeability calculations performed with conventional methods. In addition, on average the method yielded a 62% increase in hydrocarbon pore-thickness when compared to conventional petrophysical analysis. / text

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The objective of this study was to develop a gas measurement chamber for the comparison of emissions from different dairy manure storage facilities. Compost bedded pack (CBP) barns are a loose housing system in which cows rest on an intensely managed compost pack. Sawdust is the primary material added to the system, along with manure and urine inputs from the cows, and the pack is stirred one to two times daily. Maintaining a high level of aerobic microbial activity in the pack is critical for cow health. Previous dairy emissions work has not included compost bedded pack barns; it was expected that the largely aerobic system would have a different emissions profile than other manure storage systems. A measurement chamber was developed to determine emission fluxes from the compost bedded pack barn surface. Infrared and electrochemical sensors measuring ammonia, methane, and carbon dioxide obtain headspace gas concentrations, temperature, and humidity each second. The relatively lower cost of each chamber, as compared to photoacoustic and gas chromatography systems, will allow a greater number to be deployed to more accurately represent the spatial variation within the system.

The move into deeper waters in the Gulf of Mexico has produced new opportunities for petroleum production, but it also has produced new challenges as different reservoir problems are encountered. This integrated reservoir characterization effort has provided useful information about the behavior and characteristics of a typical unconsolidated, overpressured, fine-grained, turbidite reservoir, which constitutes the majority of the reservoirs present in the Outer Continental Shelf of the Gulf of Mexico. Reservoirs in the Green Canyon 18 (GC 18) field constitute part of a turbidite package with reservoir quality typically increasing with depth. Characterization of the relatively shallow 8 reservoir had hitherto been hindered by the difficulty in resolving its complex architecture and stratigraphy. Furthermore, the combination of its unconsolidated rock matrix and abnormal pore pressure has resulted in severe production-induced compaction. The reservoir's complex geology had previously obfuscated the delineation of its hydrocarbon accumulation and determination of its different resource volumes. Geological and architectural alterations caused by post-accumulation salt tectonic activities had previously undermined the determination of the reservoir's active drive mechanisms and their chronology. Seismic interpretation has provided the reservoir geometry and topography. The reservoir stratigraphy has been defined using log, core and seismic data. With well data as pilot points, the spatial distribution of the reservoir properties has been defined using geostatistics. The resulting geological model was used to construct a dynamic flow model that matched historical production and pressure data.. The reservoir's pressure and production behavior indicates a dominant compaction drive mechanism. The results of this work show that the reservoir performance is influenced not only by the available drive energy, but also by the spatial distribution of the different facies relative to well locations. The study has delineated the hydrocarbon bearing reservoir, quantified the different resource categories as STOIIP/GIIP = 19.8/26.2 mmstb/Bscf, ultimate recovery = 9.92/16.01 mmstb/Bscf, and reserves (as of 9/2001) = 1.74/5.99 mmstb/Bscf of oil and gas, respectively. There does not appear to be significant benefit to infill drilling or enhanced recovery operations.

Compost bedded pack (CBP) barn design and pack maintenance procedures vary considerably, making advising and problem-solving challenging. One objective of this research was to characterize herd performance and management practices employed by Kentucky CBP managers (42 farms and 47 CBP facilities). Producer satisfaction, changes in historical bulk-tank somatic cell count, and improvement in herd performance parameters after transitioning to a CBP barn support reported CBP barn system benefits. Daily milk production increased from before moving into the CBP barn to the second year after (29.3 ± 0.3 vs. 30.7 ± 0.3 kg, respectively; P < 0.05) for farms using the CBP barn as the primary housing facility (n = 8). Increasing stirring frequency, stirring depth, and ambient temperatures increased pack temperature. Increased drying rate decreased CBP moisture. Increased 20.3 cm depth CBP temperature and ambient temperatures improved cow hygiene. Mastitis-causing bacteria thrive in conditions similar to optimal composting bacteria conditions, making reduction of these bacteria difficult in an active composting environment. Producers must pay attention to other management areas where preventive measures can be employed. The New Dairy Housing Investment Analysis Dashboard provides users an interactive and flexible decision tool to make more informed facility investment decisions.

Reliable assessment of static and dynamic petrophysical properties of hydrocarbon-bearing reservoirs is critical for estimating hydrocarbon reserves, identifying good production zones, and planning hydro-fracturing jobs. Conventional well-log interpretation methods are adequate to estimate static petrophysical properties (i.e., porosity and water saturation) in formations consisting of thick beds. However, they are not as reliable when estimating dynamic petrophysical properties such as absolute permeability, movable hydrocarbon saturation, and saturation-dependent capillary pressure and relative permeability. Additionally, conventional well-log interpretation methods do not take into account shoulder-bed effects, radial distribution of fluid saturations due to mud-filtrate invasion, and differences in the volume of investigation of the various measurements involved in the calculations. This dissertation introduces new quantitative methods for petrophysical and compositional evaluation of water- and hydrocarbon-bearing formations based on the combined numerical simulation and nonlinear joint inversion of conventional well logs. Specific interpretation problems considered are those associated with (a) complex mineral compositions, (b) mud-filtrate invasion, and (c) shoulder-bed effects. Conventional well logs considered in the study include density, photoelectric factor (PEF), neutron porosity, gamma-ray (GR), and electrical resistivity. Depending on the application, estimations yield static petrophysical properties, dynamic petrophysical properties, and volumetric/weight concentrations of mineral constituents. Assessment of total organic carbon (TOC) is also possible in the case of hydrocarbon-bearing shale. Interpretation methods introduced in this dissertation start with the detection of bed boundaries and population of multi-layer petrophysical properties with conventional petrophysical interpretation results or core/X-Ray Diffraction (XRD) data. Differences between well logs and their numerical simulations are minimized to estimate final layer-by-layer formation properties. In doing so, the interpretation explicitly takes into account (a) differences in the volume of investigation of the various well logs involved, (b) the process of mud-filtrate invasion, and (c) the assumed rock-physics model. Synthetic examples verify the accuracy and reliability of the introduced interpretation methods and quantify the uncertainty of estimated properties due to noisy data and incorrect bed boundaries. Several field examples describe the successful application of the methods on (a) the assessment of residual hydrocarbon saturation in a tight-gas sand formation invaded with water-base mud (WBM) and a hydrocarbon-bearing siliciclastic formation invaded with oil-base mud (OBM), (b) estimation of dynamic petrophysical properties of water-bearing sands invaded with OBM, (c) estimation of porosity and volumetric concentrations of mineral and fluid constituents in carbonate formations, and (d) estimation of TOC, total porosity, total water saturation, and volumetric concentrations of mineral constituents in the Haynesville shale-gas formation. Comparison of results against those obtained with conventional petrophysical interpretation methods, commercial multi-mineral solvers, and core/XRD data confirm the advantages and flexibility of the new interpretation techniques introduced in this dissertation for the quantification of petrophysical and compositional properties in a variety of rock formations. / text

Features typical for karst, such as fast groundwater flow and existence of open conduits were observed in various parts of Bohemian Cretaceous Basin (BCB). So far, vertical and areal extent of karst rocks is not known. In case of concerning conduits in quartz sandstones the observation of their evolution in profiles perpendicular to flow is missing. The thesis deals with above mentioned issues. Concerning potential to karstification it is limited to Jizera facial area of BCB. For this purpose, leaching of samples in hydrochloric acid were carried out. The hydrochloric acid was used as an accelerated simulation of natural processes of dissolution of rock by acidic solutions. The reaction of samples on leaching in acid, disintegration and content of the CaCO3 component were evaluated. CaCO3 content was determined also by calcimetry. Rocks which disintegrated can be a suitable for the evolution of karst conduits. According to the lithostratigraphic sections, the examined profiles belong to the TUR5 and TUR6 units - thus these units contain rocks suitable for the evolution of karst conduits. In Předměřice site about 23 % of samples disintegrated, in Kosmonosy site 8 % and in Turnov site 36 % disintegrated. Thus about 1/10 to 1/3 of tested profiles is prone to karstification and evolution of karst...