acase@tulane.edu / Fault growth is often accomplished by linking a series of en echelon faults through relay ramps. A relay ramp is the area between two overlapping fault segments that tilts and deforms as the faults accrue displacement. The structural evolution of breached normal fault relay ramps remains poorly understood because of the difficulty in defining how slip is partitioned between the most basinward fault (known as the outboard fault, which includes the severed fault tip), the overlapping fault (inboard fault), and any ramp-breaching linking faults. Along the Warner Valley fault in south-central Oregon, two relay ramps displaying different fault linkage geometries are lined with a series of pluvial shorelines that record a Pleistocene paleolake regression. The inner edges of these shorelines act as paleo-horizontal datums that have been deformed by fault activity, and are used to measure relative slip variations across the relay ramp bounding faults. By measuring the elevation changes using a 10m digital elevation model (DEM) of shoreline inner edges, I estimate the amount of fault activity on severed fault tips. In order to attribute shoreline deformation to fault activity I identify shoreline elevation anomalies, where deformation exceeds a ± 0.3% window from normalized elevation values; this encompasses my conservative estimates of natural variability in the shoreline geomorphology and the error associated with the data collection. For each ramp-breaching fault style activity is concentrated near the fault linkage site. Even after a ramp is fully breached the severed fault tip temporarily retains some connectivity to the main fault segment. Severed fault tips along a mid-ramp breach tend to be more active than the severed fault tip at a footwall breach. Persistent fault activity along the entire severed fault tip is dependent on the position of the linkage. These results indicate that on the time scale of 104 years after linkage, severed fault tips persist as active structures and accommodate meaningful amounts of strain. / 1 / Christopher Samuel Young

[pt] Rampas de revezamento (RRs) são zonas altamente deformadas e que representam caminhos preferenciais do fluxo de fluidos nos reservatórios do pré-sal. O trabalho reside no estudo do comportamento do fluxo de fluidos e da poropressão em diferentes geometrias de RRs, para cenários de injeção e produção de um reservatório carbonático. Foram construídos dois modelos 2D de RR: soft-linked e hard-linked, e atribuído a eles propriedades para os materiais matriz, RR e zona de falha e definidas as condições iniciais e de contorno. Para cada modelo foram gerados três submodelos, nos quais se variou a posição dos poços. Definiu-se dois pontos observadores, um para cada modelo, no centro das RRs e foram testados sete cenários. Os resultados mostraram que, de maneira geral, as rampas soft-linked promovem uma maior comunicação no reservatório do que as rampas hard-linked. A influência da geometria da rampa foi significativa nas condições em que a permeabilidade da rampa e da matriz eram mais baixas e a poropressão não apresentou grande variação, ou seja, em reservatórios carbonáticos, cujo fluxo é dominado principalmente por falhas e fraturas. Contudo, à medida que a porosidade e permeabilidade aumentaram, assim como a variação da poropressão, a geometria da rampa passou a ter uma importância secundária comparada à disposição dos poços, ou seja, em reservatórios carbonáticos, cuja matriz é de boa qualidade permo-porosa. As fraturas na RR, a depender da direção em relação ao campo de tensões, tornaram o fluxo tortuoso. O estudo realizado trouxe importantes informações que podem auxiliar na otimização de malhas de drenagem de reservatórios carbonáticos e na recuperação dos hidrocarbonetos. / [en] Relay Ramps (RRs) are highly deformed zones and represent preferential fluid flow paths in pre-salt reservoirs. The purpose of this work is to study the behavior of fluid flow and poropressure in different relay ramp (RR) geometries, for injection and production scenarios of a carbonate reservoir development. Two 2D ramp models were built: soft-linked and hard-linked, assigned properties for the matrix, relay ramp and fault zone (damage zone and fault core) materials and defined initial and boundary conditions. For each model three sub models were generated, in which the position of the wells variated. Two observer points were defined, one for each model, in the center of the RRs and seven scenarios were tested. The results showed that, in general, soft-linked ramps promote greater reservoir communication than hard-linked ramps. The geometry influence of the ramp was significant in the conditions where the ramp and matrix permeability were lower and the poropressure did not vary much, that is, in carbonate reservoirs, whose flow is mainly dominated by faults and fractures. However, as porosity and permeability increased in the ramp and matrix, as well as the variation of poropressure, the geometry of the ramp became of secondary importance compared to the wells layout, that is, in carbonate reservoirs, whose matrix has high porosity and permeability. The fractures in RR, depending on the direction in relation to the stress field, made the flow tortuous. The study brought important information that can help in the optimization of drainage plan in carbonate reservoirs and the recovery of hydrocarbons.