The Middle Ordovician Ancell Group, including the St. Peter Sandstone, Glenwood Shale and Starved Rock Formation, records intracontinental basin development during eustatic sea level changes in Iowa and Illinois. The St. Peter Sandstone overlies the Prairie du Chien Group across an erosional unconformity that marks a major sequence boundary, whereas upper contact of the St. Peter Sandstone with the Glenwood Shale also is a second sequence boundary. Data from 80 wells, selected well logs, and 20 cores were integrated to refine the high-resolution sequence stratigraphy of the Ancell Group. Two main sequences bounded by three sequence boundaries are interpreted to represent 3rd order sequences. Distinctive shallowing-upward parasequences bounded by flooding surfaces in many cores record higher frequency relative sea level fluctuations in the Ancell Group, but these cannot presently be correlated regionally. Facies variations define an aggradational transgressive systems tract TST), a prograding highstand systems tract (HST) and down stepping falling stage system tract (FSST) in both the St. Peter Sandstone and the Glenwood Shale-Starved Rock Formation units. The St. Peter Sandstone thickens towards the northeast and thins to the northwest and southwest in Iowa. In contrast, the St. Peter Sandstone in Illinois thickens to the south likely recording a prolonged FSST incised valley or channel fill. Detrital zircon geochronology of 13 samples from the St. Peter Sandstone and Starved Rock Formation define common peaks at 1100-1500 Ma and 2500-2700 Ma with minor components at 1670-1750 Ma and 3000-3600 Ma. The detrital zircon signature is dominated by Archean, and Grenville (1000-1300 Ma) ages. The detrital zircon geochronology indicates that the Ancell Group was sourced directly from the Archean Superior Province to the north and Grenville Province to the northeast, although recycling of Archean grains from the Paleoproterozoic Huron Basin cannot be ruled out. The near complete lack of 1800-1900 Ma ages argues against derivation of detritus from the Trans-Hudson or Penokean Orogens. The Transcontinental Arch northwest of the Iowa Basin acted as a barrier to sediment transport from the Trans-Hudson Orogen. Basement rocks of the Penokean Orogen are inferred to have been covered by water or younger sediments southeast of the Iowa Basin. CIA analyses of Ordovician shale samples from around the Transcontinental Arch indicate that the climate condition during Middle Ordovician time was warm and humid. This is consistent with a paleoclimate interpretation where mechanical erosion and chemical weathering yielded first cycle mature quartz arenites (Witzke, 1980).

[pt] A presente tese apresenta e discute metodologias para prever o volume de óleo recuperável em bacias petrolíferas e explicar a evolução do processo de descoberta. A evolução do processo de descoberta é modelada pelo produto de duas funções matemáticas de tendências opostas: a função seleção de controle, crescente, que representa o grau de conhecimento e informação adquiridos na região de exploração, e a função seleção de condições, decrescente, indicando que a condição de exploração piora em conseqüência da depleção da área considerada. São propostas três novas metodologias que utilizam funções de controle nãolineares para explicar a influência do progresso tecnológico no acréscimo dos volumes recuperáveis. Além disso, utiliza-se o esforço exploratório, representado pela quantidade de poços já perfurados, como variável explicativa para as funções de controle e condição. As metodologias acima mencionadas foram testadas utilizando dados históricos referentes a cinco bacias petrolíferas. Após avaliar a capacidade explicativa dos modelos através do ajuste aos dados históricos, foram feitas previsões (out of sample) para um horizonte de 3 e 10 anos com o objetivo de avaliar a capacidade preditiva. Os testes feitos com dados de quatro diferentes bacias indicam que o uso do esforço de perfuração como variável explicativa pode melhorar a previsão a longo prazo. A análise nos resíduos dos modelos propostos indica que os modelos têm boa capacidade explicativa, pois capturaram a informação contida nos dados descrevendo satisfatoriamente o processo de evolução de descobertas nas séries observadas. / [en] This dissertation presents methodologies to forecast the recoverable oil volume in sedimenary basins and to explain the evolution of the discovery process. The evolution of the discovery process is modeled as the product of two mathematical functions of opposing trends, namely, the control function, increasing, which represents the degree of knowledge and information acquired in the exploration region, and the condition function, decreasing, indicating that the exploration condition worsens with time as a consequence of the area depletion. Three new methodologies are proposed using nonlinear control functions to explain the influence of technological progress in the reserves accrual. Acting as a proxy for exploratory effort, the drilling footage is used as an explanatory variable for both the control and the condition functions. The aforementioned methodologies were tested using a dataset of five petroliferous basins. After evaluating the explicative capacity by fitting the models to the historical data, out of sample forecast were made for a horizon of 3 and 10 years. The results using a dataset of four different basins indicate that the drilling footage can improve the long-term forecast. The analysis in the residues of the proposed models indicates that the models captured the information contained in the data and satisfactorily describes the process of evolution of discoveries in the observed series.