This study provides independent analysis of Residual Oil Zones (ROZs) in the Permian Basin from a regional perspective, focusing on the formation mechanism and present ROZ locations. Results demonstrate widespread potential for ROZs, defined here as thick volumes of reservoir rock containing near-residual saturations of predominantly immobile oil formed by natural imbibition and displacement of oil by dynamic buoyant or hydrodynamic forces. Previous work suggests hydrodynamic forces generated by regional tectonic uplift drove widespread oil remobilization and ROZ creation. To test the hypothesis, uplift and tilting are quantified and the resulting peak regional potentiometric gradient used as a physical constraint to compute and compare predicted ROZ thicknesses from hydrodynamics for several ROZ-bearing San Andres fields with known ROZ thicknesses. Late-Albian Edwards Group geologic contacts, which are interpreted to have been deposited near sea level prior to uplift, are used as a regional datum. Approximate elevations determined for the present datum show ~1800 m of differential uplift since Edwards deposition, with an average regional slope of ~0.128˚. This post-Edwards tilting increased the pre-existing regional structural gradient of the San Andres Formation to ~0.289˚. Using the calculated post-Edwards gradient results in to prediction of ROZ thicknesses from hydrodynamics that is consistent with measured ROZ thicknesses at several fields. When compared with countervailing buoyancy forces, hydrodynamics is calculated to be the more dominant driving force of oil movement for reservoirs with structural dips less than 1.5˚, which is the common dip for San Andres Formation platform deposits where ROZs have been identified. To predict the location of ROZs, ROZ-related oil field properties were identified and analyzed for over 2,800 Permian Basin reservoirs. A strong basin-wide correlation between API and crude sulfur content is consistent with the expected outcome of oil degradation driven by oil-water interaction, and supports the use of API and sulfur content as proxies for ROZ potential in the Permian Basin. Spatial analysis of sulfur data shows that the highest probability for ROZ existence exists in Leonardian through Guadalupian-age reservoirs, distributed primarily in shelf and platform areas of Permian structures. Combined, these results support the widespread potential for ROZs across the Permian Basin generated primarily by regional scale tilting and resultant hydrodynamic forces. / text

The Permo-Carboniferous Dwyka Group and Vryheid Formation of the Karoo. Sequence in the Highveld Coalfield are analysed to determine the depositional systems operative during sedimentation. The investigation involves the processing of "629" borehole cores and logs in an area of 860km2.[Abbreviated Abstract. Open document to view full version] / AC2017

Análises palinológicas desenvolvidas com depósitos do Estado do Rio Grande do Sul estiveram, em sua maioria, relacionadas ao estudo das jazidas de carvão da Formação Rio Bonito, que resultaram na identificação de associações palinológicas vinculadas a formação de paleoturfeiras. O consequente reconhecimento das demais associações palinológicas da passagem entre o Grupo Itararé e a Formação Rio Bonito é menos detalhado, necessitando-se aprimorar os limites da paleovegetação e das palinozonas estabelecidas. Esta dissertação compreende a análise palinológica de níveis do poço ST-01-RS, localizado na região de Cachoeira do Sul, centro do Rio Grande do Sul. Um total de 25 (vinte e cinco) amostras de subsuperfície foi coletado, envolvendo o intervalo entre o Grupo Itararé e a Formação Rio Bonito. A análise palinológica permitiu a identificação de 28 gêneros de palinomorfos, dentre os quais 08 (oito) são relativos a esporos triletes acavados, 04 (quatro) a esporos triletes cavados cingulizonados, 05 (cinco) relativos a grãos de pólen monossacados, 01 (um) a grão de pólen bissacado liso e 09 (nove) a grãos de pólen estriados e pré-colpados, enquanto 04 (quatro) formas são relacionadas a elementos constituintes do microplâncton (algas clorofíceas), 01 (um) gênero de esporo de fungo 01 (um) acritarco não determinado. As características quantitativas dos conjuntos palinológicos recuperados permitiram a proposição de 02 (duas) fases palinoflorísticas, designadas como Fase I, ocorrente entre as porções inferior e média do testemunho (Grupo Itararé) e Fase II, que abrange o topo do Grupo Itararé e a Formação Rio Bonito. As distribuições dos táxons nas duas unidades revelaram que a Fase I representa uma paleovegetação herbácea composta predominantemente de Pteridospermopsida (esporos) em um ambiente com condições climáticas úmidas; espécimes de Gimnospermopsida (grãos de pólen) são subordinados. Durante a Fase II, a vegetação caracteriza-se por alterações parciais do contexto da Fase I, ainda com Pteridospermopsida dominantes, porém com maior participação da vegetação arborescente (Gimnospermopsida) em paleoambiente de clima úmido nas áreas mais baixas relacionadas aos corpos d’água provavelmente circundado por áreas mais elevadas cobertas por representante de Gimnospermopsida. Em ambas as fases, algas e esporos de fungos são escassos. O Grupo Itararé e a Formação Rio Bonito apresentam 7 conjuntos palinológicos semelhantes, com variações nas proporções entre gêneros de uma unidade para a outra, bem como registrado em outros trabalhos realizados em depósitos do Rio Grande do Sul, o que demonstra a existência de discretas e locais variações paleoclimáticas e paleoambientais. / Palynological analysis developed with deposits in the State of Rio Grande do Sul were mostly related to the study of the coal deposits of the Rio Bonito Formation, which resulted in the identification of palynological associations related to paleo peat-forming. The consequent recognition of the other palinological associations of the passage between the Itararé Group and the Rio Bonito Formation is less detailed and it is necessary to improve the limits of the palaeovegetation and palinozones established. This dissertation comprises the palynological study of levels of well ST-01-RS, located in the region of Cachoeira do Sul, central Rio Grande do Sul state. A total of 25 (twenty-five) subsurface samples were collected, involving the interval between the Itararé Group and the Rio Bonito Formation. The palynological analysis allowed the identification of 29 (twenty-nine) genera of palynomorphs, of which 08 (eight) were related to trilete spores, 05 (five) related to monosacted pollen grains, 01 (one) the grain of laevigati pollen grains and 09 (nine) pollen grains are praecolpati, while 04 (four) forms are related to constituent elements of the microplankton (algae), 01 (one) genus of fungi spore and 01 (one) acritarch not determined. The quantitative characteristics of the recovered palynological assemblages allowed the proposition of 02 (two) palinofloristic phases, designated as Phase I, occurring between the lower and middle portions of the well (Itararé Group) and Phase II, which covers the top of the Itararé Group and Rio Bonito Formation. The distributions of the taxa in the two units revealed that Phase I presents an herbaceous paleovegegation composed predominantly of Pteridospermopsida (spores) in an environment with humid climatic conditions; specimens of Gimnospermopsida (pollen grains) are subordinate. During Phase II, vegetation is characterized by partial alterations of the Phase I context, still with dominant Pteridospermopsida, but with an increase of the arborescent vegetation (Gimnospermopsida) in a humid climate paleoenvironment in the lower areas related to probably circled water bodies by higher areas covered by representative of Gymnospermopsida. In both phases, algae and fungi spores are scarce. The Itararé Group and the Rio Bonito Formation have similar palynological assemblages, with variations in the proportions between genera from one unit to the other, as well as recorded in other studies carried out in Rio Grande do Sul deposits, which demonstrates the existence of discrete and localy paleoclimatic and paleoenvironmental changes.

Resumo: Bivalves fósseis são comuns em rochas siliciclásticas e carbonáticas das formações Teresina e Rio do Rasto (Permiano Médio/Superior), Bacia do Paraná. Entretanto, a gênese das camadas de conchas carbonáticas ainda é pouco conhecida. Cinco camadas de calcários do centro-sul e norte do Estado do Paraná foram selecionados para estudo tafonômico: dois grainstones oolíticos a bivalves (Prudentópolis) e um grainstone a peloides e bivalves com intraclastos e oncoides (Rio Preto) da Formação Teresina; um packstone e um wackestone a bivalves e oncoides (Ribeirão Claro) da Formação Rio do Rasto. As camadas carbonáticas (≤ 45 cm de espessura), estão intercaladas entre rochas pelíticas, possuem contato basal erosivo, quantidade variável de intraclastos pelíticos, valvas caoticamente distribuídas com gradação vertical descontínua e empacotamento denso a disperso. As conchas encontram-se desarticuladas, comumente fragmentadas, às vezes incrustadas por cianobactérias, e correspondem a espécies alóctonas que viviam em substratos distintos. As assembléias de bivalves representam, portanto, tanatocenoses em tempestitos proximais amalgamados, gerados em água rasa com frequentes modificações por bioturbação e baixa taxa de sedimentação. A presente pesquisa corrobora outras evidências de que acumulações de conchas paleozóicas em mares epicontinentais resultaram de história tafonômica complexa com acentuada mistura temporal e espacial dos bioclastos sob influência de tempestades / Abstract: Bivalve fossils are common in siliciclastic and carbonate rocks of the Teresina and Rio do Rasto formations (Middle to Late Permian), Paraná Basin. However, little is known about shell concentrations in carbonates. Five limestone beds in south-central and northern Paraná State were selected for a taphonomic study: two oolite-bivalve grainstones at Prudentópolis and one peloid-bivalve grainstone with intraclasts and oncoids at Rio Preto, from Teresina Formation; one packstone and one wackestone with bivalves and oncoids at Ribeirão Claro, from Rio do Rasto Formation. The limestone beds (≤ 45 cm thick) are intercalated with pelitic rocks; the basal contact is sharp and erosive, with variable amount of pelitic intraclasts. Shells are randomly oriented (many nested/stacked), showing dense to disperse packing, and discontinuous grading. The shells are disarticulated, commonly fragmented, sometimes encrusted by stromatolites, and correspond to allochthonous specimens winnowed from distinct life-substrates. The bivalve concentrations were generated in shallow water settings punctuated by storms, under very low sedimentation rates, with frequent intrastratal bioturbation. Hence, the concentrations are amalgamated proximal tempestites. This work corroborates previous evidences that Paleozoic shell beds from the epeiric seas have complex taphonomic histories and result from strong temporal/spatial mixing of bioclasts under storm influence / Orientador: Rosemarie Rohn Davies / Coorientador: Marcello Guimarães Simões / Banca: Joel Carneiro de Castro / Banca: Sabrina Coelho Rodrigues / Mestre

Two hydrogeologic models explore reflux dolomitization using two outcrop datasets at different scales to constrain transient boundary conditions and heterogeneous petrophysical properties. A platform-scale petrophysical model of the Permian San Andres Formation was built from outcrop and subsurface data following a reservoir modeling approach that preserves outcrop heterogeneity and incorporates a sequence stratigraphic framework. This model was used as input for hydrogeological simulations of hypersaline fluid flow and solute transport during the accumulation and compaction of the platform. Boundary conditions change over time, as relative sealevel fluctuations drive sedimentation, depositional environment migration, topographic gradients, and location, size and salinity of the brine source. The potential volume and distribution of dolomite formed is inferred by a magnesium mass-balance. The composite result of reflux events at various orders of stratigraphic hierarchy is a complex dolomite pattern that resembles that observed on San Andres outcrops. Dolostone bodies across the platform may be generated by different combinations of favorable conditions, including proximity to the brine source, zones of higher permeability, permeability contrasts, and latent reflux. A meter-scale reactive transport model of the Albian Upper Glen Rose Formation simulates deposition of three high-frequency cycles punctuated by three brine reflux events. The simulator determines flow, solute and reactive transport along the flow paths, revealing the spatial and temporal distribution of calcite dissolution, and precipitation of dolomite and sulfate. The model recreates fully and partially dolomitized cycles within the time and lithological constrains on Glen Rose outcrops. Our results show that the distribution of dolomite within a high-frequency cycle may be the net result of intercycle processes, whereby dolomitizing fluids sourced from younger cycles flow across stratigraphically significant boundaries. We also show that variations in dolomite abundance and the unfulfilled dolomitization potential control the contemporaneous propagation of multiple dolomite fronts and the coalescence of discrete dolomite bodies. Results show that reflux is an effective and efficient mechanism to dolomitize carbonate formations that progresses simultaneously with sediment accumulation. Dolomitization is the cumulative result of many short-lived reflux events, sourced in different locations and times, and amalgamation of successive dolostone bodies. This model contrasts with previous studies that approached dolomitization of a carbonate platform as a discrete reflux event and current interpretations that relate dolomite bodies to their most immediate stratigraphic surfaces. / text

No description available.

This study integrates sequence stratigraphy of the Late Permian Toolachee Formation in the non-marine intracratonic Permian-Triassic Cooper Basin, Australia with 3-D seismic attribute analysis to predict the extent of depositional environments identified on wireline and well core data. The low resolution seismic data (tuning thickness 23 - 31 m) comprised of six seismic horizons allowed the successful testing of sequence stratigraphic interpretations of the productive Toolachee Formation that were based on wireline data. The analysis of 29 well logs and three 20 m core intervals resulted in the identification of eleven parasequences that comprise the building blocks of an overall transitional systems tract, characterised by a gradual increase in accommodation. The parasequences reflect cyclic transitions between braided and meandering fluvial systems as a result of fluctuations in sediment flux, possibly driven by Milankovitch climatic-forcing. The seismic horizon attribute maps image mostly the meandering fluvial bodies within the upper parts of the parasequences, but some maps image the lower amalgamated sand sheets and show no channel structures. Categorisation of the fluvial bodies in the overbank successions reflects a gradual decrease in sinuosity, channel width, and channel belt width up-section, supporting the overall increase in accommodation up-section. Similar acoustic impedance values for shales and sands do not suggest successful seismic forward modelling between the two lithologies. Geological interpretations suggest most imaged channel fill to be made up predominantly of fine sediments, as channel avulsion and abandonment is common and increases with time. Seismic forward modelling resulted in the interpretation of carbonaceous shale as a possible channel fill, supporting the geological interpretations. The three major identified fluvial styles; braided, meanders, and distributaries are potential targets for future exploration. Extensive sand sheets deposited from braided fluvial systems require structural traps for closure. Meandering and anastomosing channel systems represent excellent stratigraphic traps, such as the basal sands/gravels of laterally accreted point bars.

No description available.

No description available.

Análises mineralógicas, petrográficas e de palinofácies são registradas em um leito de tonstein associado a camadas de carvão na Jazida do Faxinal, Rio Grande do Sul, Brasil. A integração dos dados revestiu-se de grande importância para atribuir uma origem vulcânica para este argilito caolinítico. O tonstein é uma rocha quase monominerálica, composta predominantemente por caolinita antigênica. Dispersos na massa caolinítica ocorrem os minerais piroclásticos: paramorfos de quartzo-ß bipiramidais euédricos, “splinters” de quartzo transparente, zircão idiomórfico, apatita euédrica, alanita e pseudomorfos de sanidina, os quais são considerados como uma suíte restrita de minerais vulcânicos de tonsteins distais que preservaram durante a diagênese. Os minerais primários e suas feições texturais, bem como as relações de campo, indicam uma origem vulcânica de queda para essa camada. O estudo de palinofácies, inédito para este tipo de rocha, evidenciou uma composição diferenciada da matéria orgânica estruturada ao longo do perfil do tonstein. Análises estatísticas do querogênio de diferentes níveis da camada de tonstein indicaram altas percentagens de fitoclastos (xilema e epiderme) associados à menor representatividade de palinomorfos. Análises microestratigráficas destes níveis demonstraram que a saturação e a precipitação dos palinomorfos foram altamente influenciadas pelo intenso processo de queda de cinzas. O nível basal caracteriza-se por densos aglomerados de esporos e polens, enquanto o topo é marcado pela preservação de fragmentos de colônias de algas Botryococcus evidenciando uma deposição subaquosa desta camada. Alguns fragmentos de epiderme (cutículas) evidenciam, por sua coloração, acentuada alteração termal. Esses dados possibilitaram vincular as peculiaridades do mecanismo de deposição e preservação da matéria orgânica com o processo de formação do tonstein relacionado à rápida precipitação de cinzas vulcânicas. O tonstein intercalado em camada de carvão indica um episódio de sedimentação de tefra durante a deposição da seqüência portadora de carvão no Permiano Inferior no sul da Bacia do Paraná. / Mineralogical and palynofacies analyses are reported from a tonstein layer interbedded with coal seams in the Faxinal coalfield, Rio Grande do Sul, Brazil. Integration of data has far reaching significance for attributing a volcanic origin for this kaolinitic claystone bed. The tonstein is almost monomineralic rock, composed mainly by authigenic kaolinite. Scattered in the kaolinitic mass primary pyroclastic minerals occur: euhedral beta-quartz paramorphs and waterclear quartz splinters, idiomorphic zircons, apatite, allanite and sanidine pseudomorphs; considered as a restricted suite of silicic volcanic minerals of the distal tonsteins which preserved during diagenesis. The primary minerals and their textural features, as well as the field relations, indicate a volcanic air-fall origin. Analyses of the kerogens from different levels of tonstein layer indicate high percentages of phytoclasts combined with very low palynomorph percentages. Microstratigraphic analyses of the tonstein profile demonstrated that saturation and precipitation of palynomorphs were highly influenced by the intense ash-fall process. The preservation of Botryococcus colonies at the top of the tonstein evidenced the subaqueous deposition of this bed. The brown color of several cuticle fragments and tracheids was linked to thermal alteration. The tonstein interbedded in a coal seam indicates an episode of tephra sedimentation during the deposition of the coal-bearing sequence of the Lower Permian in the southern Paraná Basin.