TY - JOUR A1 - Agada, S. A1 - Chen, F. A1 - Geiger, S. A1 - Toigulova, G. A1 - Agar, Susan M. A1 - Shekhar, R. A1 - Benson, Gregory S. A1 - Hehmeyer, O. A1 - Amour, Frédéric A1 - Mutti, Maria A1 - Christ, Nicolas A1 - Immenhauser, A. T1 - Numerical simulation of fluid-flow processes in a 3D high-resolution carbonate reservoir analogue JF - Petroleum geoscience N2 - A high-resolution three-dimensional (3D) outcrop model of a Jurassic carbonate ramp was used in order to perform a series of detailed and systematic flow simulations. The aim of this study was to test the impact of small- and large-scale geological features on reservoir performance and oil recovery. The digital outcrop model contains a wide range of sedimentological, diagenetic and structural features, including discontinuity surfaces, shoal bodies, mud mounds, oyster bioherms and fractures. Flow simulations are performed for numerical well testing and secondary oil recovery. Numerical well testing enables synthetic but systematic pressure responses to be generated for different geological features observed in the outcrops. This allows us to assess and rank the relative impact of specific geological features on reservoir performance. The outcome documents that, owing to the realistic representation of matrix heterogeneity, most diagenetic and structural features cannot be linked to a unique pressure signature. Instead, reservoir performance is controlled by subseismic faults and oyster bioherms acting as thief zones. Numerical simulations of secondary recovery processes reveal strong channelling of fluid flow into high-permeability layers as the primary control for oil recovery. However, appropriate reservoir-engineering solutions, such as optimizing well placement and injection fluid, can reduce channelling and increase oil recovery. Y1 - 2014 U6 - https://doi.org/10.1144/petgeo2012-096 SN - 1354-0793 VL - 20 IS - 1 SP - 125 EP - 142 PB - Geological Soc. Publ. House CY - Bath ER - TY - JOUR A1 - Amour, Frederic A1 - Mutti, Maria A1 - Christ, Nicolas A1 - Immenhauser, Adrian A1 - Agar, Susan M. A1 - Benson, Gregory S. A1 - Tomas, Sara A1 - Alway, Robert A1 - Kabiri, Lachen T1 - Capturing and modelling metre-scale spatial facies heterogeneity in a Jurassic ramp setting (Central High Atlas, Morocco) JF - Sedimentology : the journal of the International Association of Sedimentologists N2 - Each simulation algorithm, including Truncated Gaussian Simulation, Sequential Indicator Simulation and Indicator Kriging is characterized by different operating modes, which variably influence the facies proportion, distribution and association of digital outcrop models, as shown in clastic sediments. A detailed study of carbonate heterogeneity is then crucial to understanding these differences and providing rules for carbonate modelling. Through a continuous exposure of Bajocian carbonate strata, a study window (320 m long, 190 m wide and 30 m thick) was investigated and metre-scale lithofacies heterogeneity was captured and modelled using closely-spaced sections. Ten lithofacies, deposited in a shallow-water carbonate-dominated ramp, were recognized and their dimensions and associations were documented. Field data, including height sections, were georeferenced and input into the model. Four models were built in the present study. Model A used all sections and Truncated Gaussian Simulation during the stochastic simulation. For the three other models, Model B was generated using Truncated Gaussian Simulation as for Model A, Model C was generated using Sequential Indicator Simulation and Model D was generated using Indicator Kriging. These three additional models were built by removing two out of eight sections from data input. The removal of sections allows direct insights on geological uncertainties at inter-well spacings by comparing modelled and described sections. Other quantitative and qualitative comparisons were carried out between models to understand the advantages/disadvantages of each algorithm. Model A is used as the base case. Indicator Kriging (Model D) simplifies the facies distribution by assigning continuous geological bodies of the most abundant lithofacies to each zone. Sequential Indicator Simulation (Model C) is confident to conserve facies proportion when geological heterogeneity is complex. The use of trend with Truncated Gaussian Simulation is a powerful tool for modelling well-defined spatial facies relationships. However, in shallow-water carbonate, facies can coexist and their association can change through time and space. The present study shows that the scale of modelling (depositional environment or lithofacies) involves specific simulation constraints on shallow-water carbonate modelling methods. KW - 3D facies modelling KW - carbonate ramp KW - facies heterogeneity KW - Jurassic KW - modelling algorithms KW - scale Y1 - 2012 U6 - https://doi.org/10.1111/j.1365-3091.2011.01299.x SN - 0037-0746 VL - 59 IS - 4 SP - 1158 EP - 1189 PB - Wiley-Blackwell CY - Malden ER - TY - JOUR A1 - Amour, Frederic A1 - Mutti, Maria A1 - Christ, Nicolas A1 - Immenhauser, Adrian A1 - Benson, Gregory S. A1 - Agar, Susan M. A1 - Tomas, Sara A1 - Kabiri, Lahcen T1 - Outcrop analog for an oolitic carbonate ramp reservoir a scale-dependent geologic modeling approach based on stratigraphic hierarchy JF - AAPG bulletin N2 - Considerable effort has been devoted to the development of simulation algorithms for facies modeling, whereas a discussion of how to combine those techniques has not existed. The integration of multiple geologic data into a three-dimensional model, which requires the combination of simulation techniques, is yet a current challenge for reservoir modeling. This article presents a thought process that guides the acquisition and modeling of geologic data at various scales. Our work is based on outcrop data collected from a Jurassic carbonate ramp located in the High Atlas mountain range of Morocco. The study window is 1 km (0.6 mi) wide and 100 m (328.1 ft) thick. We describe and model the spatial and hierarchical arrangement of carbonate bodies spanning from largest to smallest: (1) stacking pattern of high-frequency depositional sequences, (2) facies association, and (3) lithofacies. Five sequence boundaries were modeled using differential global position system mapping and light detection and ranging data. The surface-based model shows a low-angle profile with modest paleotopographic relief at the inner-to-middle ramp transition. Facies associations were populated using truncated Gaussian simulation to preserve ordered trends between the inner, middle, and outer ramps. At the lithofacies scale, field observations and statistical analysis show a mosaiclike distribution that was simulated using a fully stochastic approach with sequential indicator simulation. This study observes that the use of one single simulation technique is unlikely to correctly model the natural patterns and variability of carbonate rocks. The selection and implementation of different techniques customized for each level of the stratigraphic hierarchy will provide the essential computing flexibility to model carbonate settings. This study demonstrates that a scale-dependent modeling approach should be a common procedure when building subsurface and outcrop models. Y1 - 2013 U6 - https://doi.org/10.1306/10231212039 SN - 0149-1423 VL - 97 IS - 5 SP - 845 EP - 871 PB - American Association of Petroleum Geologists CY - Tulsa ER - TY - JOUR A1 - Whitaker, F. F. A1 - Felce, G. P. A1 - Benson, Gregory S. A1 - Amour, Frédéric A1 - Mutti, Maria A1 - Smart, P. L. T1 - Simulating flow through forward sediment model stratigraphies: insights into climatic control of reservoir quality in isolated carbonate platforms JF - Petroleum geoscience N2 - Whilst sophisticated multiphase fluid flow models are routinely employed to understand behaviour of oil and gas reservoirs, high-resolution data describing the three-dimensional (3D) distribution of rock characteristics is rarely available to populate models. We present a new approach to developing a quantitative understanding of the effect of individual controls on the distribution of petrophysical properties and their impact on fluid flow. This involves simulating flow through high-detail permeability architectures generated by forward modelling of the coupled depositional-diagenetic evolution of isolated platforms using CARB3D(+). This workflow is exemplified by an investigation of interactions between subsidence and climate, and their expression in spatial variations in reservoir quality in an isolated carbonate platform of similar size and subsidence history to the Triassic Latemar Platform. Dissolutional lowering during subaerial exposure controls platform-top graininess via platform top hydrodynamics during the subsequent transgression. Dissolved carbonate is reprecipitated as cements by percolating meteoric waters. However, associated subsurface meteoric dissolution generates significant secondary porosity under a more humid climate. Slower subsidence enhances diagenetic overprinting during repeated exposure events. Single-phase streamline simulations show how early diagenesis develops more permeable fairways within the finer-grained condensed units that can act as thief zones for flow from the grainier but less diagenetically altered cyclic units. Y1 - 2014 U6 - https://doi.org/10.1144/petgeo2013-026 SN - 1354-0793 VL - 20 IS - 1 SP - 27 EP - 40 PB - Geological Soc. Publ. House CY - Bath ER - TY - JOUR A1 - Shekhar, R. A1 - Sahni, I. A1 - Benson, Gregory S. A1 - Agar, Susan M. A1 - Amour, Frédéric A1 - Tomas, Sara A1 - Christ, Nicolas A1 - Alway, Robert A1 - Mutti, Maria A1 - Immenhauser, A. A1 - Karcz, Z. A1 - Kabiri, L. T1 - Modelling and simulation of a Jurassic carbonate ramp outcrop, Amellago, High Atlas Mountains, Morocco JF - Petroleum geoscience N2 - Carbonate reservoirs pose significant challenges for reservoir modelling and flow prediction due to heterogeneities in rock properties, limits to seismic resolution and limited constraints on subsurface data. Hence, a systematic and streamlined approach is needed to construct geological models and to quickly evaluate key sensitivities in the flow models. This paper discusses results from a reservoir analogue study of a Middle Jurassic carbonate ramp in the High Atlas Mountains of Morocco that has stratigraphic and structural similarities to selected Middle East reservoirs. For this purpose, high-resolution geological models were constructed from the integration of sedimentological, diagenetic and structural studies in the area. The models are approximately 1200 x 1250 m in size, and only faults (no fractures) with offsets greater than 1 m are included. Novel methods have been applied to test the response of flow simulations to the presence or absence of specific geological features, including proxies for hardgrounds, stylolites, patch reefs, and mollusc banks, as a way to guide the level of detail that is suitable for modelling objectives. Our general conclusion from the study is that the continuity of any geological feature with extreme permeability (high or low) has the most significant impact on flow. Y1 - 2014 U6 - https://doi.org/10.1144/petgeo2013-010 SN - 1354-0793 VL - 20 IS - 1 SP - 109 EP - 123 PB - Geological Soc. Publ. House CY - Bath ER -