Milovan Fustic - Academia.edu (original) (raw)

Papers by Milovan Fustic

Sedimentary geology, May 1, 2024

Frontiers in Earth Science, Nov 21, 2023

The objective of this thesis was to investigate the relationship between reservoir properties and... more The objective of this thesis was to investigate the relationship between reservoir properties and petroleum composition in the Athabasca Oil Sands reservoir, and to develop concepts for predicting and mapping petroleum properties in different parts of the reservoir. To achieve this said objective, several disciplines including geochemistry and sedimentology have been integrated. Interpretation of the geochemical results within a geological framework allowed an assessment of the impact of sedimentary and other geological features upon the bitumen composition and for interpreting reservoir charging and in-reservoir fluid mixing. The major conclusions are documented in five consecutive papers: 1) The downstream translation of tidally influenced meandering river bends was a dominant process during the deposition of the McMurray Formation, and that this process is responsible for creating a labyrinth of large scale reservoir and nonreservoir depositional elements that form a complex, but predictable and mappable network of reservoir compartments. 2) The reservoir is compartmentalized by sedimentary features (mud plugs), which has resulted in charging via the "fill and spill" mechanism along the network of reservoirs leading to the most mature oil encountered in compartments closer to the source and the least mature oil accumulating in compartments further from the source. 3) The stratigraphic dip analysis technique can be applied as a powerful tool for mapping the lateral extent of individual point bar deposits as well as for predicting the reservoir quality.

SEPM (Society for Sedimentary Geology) eBooks, 2011

NEXEN Inc. and OPTI Canada Inc. formed a 50/50 joint venture to develop the Long Lake property lo... more NEXEN Inc. and OPTI Canada Inc. formed a 50/50 joint venture to develop the Long Lake property located about 40 km southeast of Fort McMurray in the Athabasca Oil Sands Region (AOSR) of northeastern Alberta (Figure 1). The project will be developed in several phases. Phase 1 development aims to produce approximately 70,000 barrels per day (b/d) of bitumen. Production will use Steam Assisted Gravity Drainage (SAGD) bitumen recovery technology that uses steam to transfer heat and mobilize extremely viscous bitumen. This technology is applied virtually in all existing and planned in-situ projects in the AOSR.

An ancient (Upper Cretaceous, 77-76.5 Ma, Oldman Formation) river meander deposit, exposed in the... more An ancient (Upper Cretaceous, 77-76.5 Ma, Oldman Formation) river meander deposit, exposed in the Steveville Badlands of Dinosaur Provincial Park, AB., exhibits extensive deformed and chaotically bedded strata. The most impressive features are large scale rotations of inclined heterolithic stratified (sandstone and shale) blocks, up to 6 m high and 50 m long, dipping in the opposite direction to that of the lateral accretion trend (Fig. 2). We observe three separate sets of reversely dipping beds along one badland gully, oriented parallel with the direction of lateral accretion. The large reverse cross-stratified structures rest on shale failure planes, suggesting the structures formed as back-rotational slumps of inclined heterolithic strata that slid down an active point bar slope into the channel before it was buried by subsequent lateral accretion sediments. Chaotic and disturbed sandstone and shale blocks, soft sediment deformation, and evidence for sediment foundering in the upper 3 m of point bar stratigraphy are common throughout the ancient meander bend, atypical of meandering river deposits (Fig. 1). Some of the broken and blocky sandstone strata displays a domino-like effect, with all blocks leaning in the same direction. Overturned sandstone beds resting on interpreted failure planes, attributed to slumping, are suggestive of down-slope failures (Fig. 3). Faulting represents the final form of deformation of stratigraphy with displacements of up to 2 m, and the hangingwall always on the channel side of the meander lobe (Fig. 4). We interpret all of these structures as having been caused by large magnitude earthquakes and tremors associated with Laramide thrusting. The three sets of reversed inclined heterolithic strata encased within normal lateral accretion bedding, are interpreted to record three major seismic events, separated by periods of relative

ABSTRACT Tidally influenced meandering river deposits of the Cretaceous middle McMurray Formation... more ABSTRACT Tidally influenced meandering river deposits of the Cretaceous middle McMurray Formation are characterized by rapid vertical and lateral lithological and associated reservoir property changes. Within the reservoir, water may occur below, above, and in the middle of the bitumen column, and there may be multiple gas intervals. Although conceptual understanding about the depositional environment and its control on distribution of different fluids (bitumen, water, and gas) is documented in literature, integration of these concepts into reservoir models and history matching through flow simulation is lacking. Thus, even in areas with closely spaced wells (as much as several hundred meters apart), geostatistical modeling approaches show high degrees of randomness. This chapter closes the gap between the conceptual mapping and numerical modeling approaches. Specifically, the workflow for creating a deterministic three-dimensional (3-D), object-based (geobody) model, which integrates data from closely spaced wells, high-quality 3-D seismic data, and sound geologic concepts is shown. The geobodies are typically large-scale depositional elements comprising meandering river deposits. Geobodies include channel lag breccia (tens to hundreds of meters wide and as much as several meters thick), lower and upper point-bar deposits (from several hundreds of meters to as much as 5 km [3 mi] wide and as much as 40m[131 ft] thick), andmud plug deposits (asmuch as 500m[1640 ft]wide and as much as 40m[131 ft] thick). Because of the potential impact on reservoir development economics, top water, top gas, and low-bitumen, high-water saturated zones are mapped as distinct geobodies. Based on their reservoir development potential, geobodies can then be classified as reservoir flow unit types 1 and 2, reservoir flow barriers, and reservoir flow impairments. Geobody mapping includes several steps. First, interpretation of geobodies in each well profile (one-dimensional interpretation) using well log (including dipmeter) and bitumen analysis data is conducted. Generally, clean, massive, or trough cross-bedded, bitumen-saturated sand, characterized with scattered dips and with a base marked by breccia or scour, and overlain by inclined heterolithic strata deposits are identified as lower point-bar deposits. Interbedded sand and mud with unidirectional dips are interpreted as laterally accreting, upper point-bar deposits. Intervals with neutron-density crossover are gas geobodies, and clean sand with low-bitumen and high-water saturation are interpreted as a distinct geobody. In the second step, geobodies interpreted in individual wells are then correlated on a series of closely spaced (100–300m[330–1000 ft] apart) cross sections and horizon slicemaps (every 10 m [33 ft]). In this step, a reliable correlation of certain geobodies between wells is supported by seismic amplitude changes occurring along geobody contacts. Other contacts, characterized by the lack of amplitude changes, are delineated using well data and applying process sedimentological concepts. All contacts are manually drawn using computerdrafting tools. The third step connects the geobodies three-dimensionally to create spatially defined triangulated geobody surfaces. This methodology honors and integrates a range of data, as well as sedimentological principles for tidally influenced meandering river depositional facies. Following mapping of the 3-D geobody surfaces, a 25 � 25 � 1-m (82 � 82 � 3.3-ft) grid is generated, and properties are assigned stochastically to preserve the spatial distribution and population for each geobody. Lithofacies are populated first, followed by porosity and permeability after logs were upscaled to match the 1 m (3.3 ft) vertical resolutions of the block model. Lithofacies proportions and variograms are computed for each geobody to account for local trends and spatial orientation. Porosity and permeability histograms and variograms are computed by lithofacies for the entire model area. Water saturation is populated per geobody using an inverse correlation with porosity based on a fieldwide relationship. This approach allows for geologic interpretation to guide the distribution of lithofacies, petrophysical, and fluid properties. Results show that in comparison with common geostatistical workflows, the stochastic simulation constrained to deterministically interpreted 3-D geobodies allows conceptual geologic interpretation to guide statistical distribution, thereby reducing uncertainties and improving the ability to visualize, simulate, and analyze production results in a geologic context. Implications for reservoir development include better placement and optimization of horizontal wells, more realistic production optimization decisions and production history matching constrained by geologic interpretation. Reduced reservoir development and production costs and maximized recoveries likely will be the outcome. This workflow…

Sedimentology, Oct 1, 2009

Counter point bar deposits in the meandering Peace River, North‐central Alberta, Wood Buffalo Nat... more Counter point bar deposits in the meandering Peace River, North‐central Alberta, Wood Buffalo National Park, are distinct from point bar deposits in terms of morphology, lithofacies and reservoir potential for fluids. Previously referred to as the distal‐most parts of point bars, point bar tails and concave bank‐bench deposits, counter point bar deposits have concave morphological scroll patterns rather than convex as with point bars. The Peace is a large river (bankfull discharge 11 700 m3 sec−1, width 375 to 700 m, depth 15 m, gradient 0·00004 or 4 cm km−1) in which counter point bar deposits are dominated by silt (80% to 90%), which contrasts with sand‐dominant (90% to 100%) point bar deposits. Beginning at the meander inflection (transition from convex to concave), counter point bar deposit stratigraphy thickens as a wedge‐like architecture in the distal direction until the deposit is nearly as thick as the point bar deposits. The low permeability silt‐dominant lithofacies in counter point bar deposits will limit reservoir extent and movement of fluids in both modern and ancient subsurface fluvial deposits. In the exploration and extraction of bitumen and heavy oil in subsurface fluvial rocks, identification and mapping of reservoir potential of point bar deposits and counter point bar deposits is now possible in the fluvial‐dominated tidal estuarine Lower Cretaceous Middle McMurray Formation, North‐east Alberta. Recent geophysical advances have facilitated imaging of some ancient buried point bar deposits and counter point bar deposits which, on the basis of morphological shape of sedimentary bodies observed from seismic amplitude, can be interpreted and mapped as depositional elements or blocks that contain associated sandstone or siltstone dominant lithofacies, respectively. As counter point bar deposits exhibit poor permeability and thus limit reservoir potential for water, natural gas, light crude, heavy oil and bitumen, counter point bar deposits should be avoided in resource developments. Geophysical imaging, interpretation and mapping of point bar deposit and counter point bar deposit elements provide new opportunities to improve recovery of bitumen and heavy oil and reduce development costs in subsurface cyclic steam stimulation and steam‐assisted gravity drainage projects by not drilling into counter point bar deposits.

Marine and Petroleum Geology, 2012

Bitumen of the Lower Cretaceous McMurray Formation in northeastern Alberta represents one of the ... more Bitumen of the Lower Cretaceous McMurray Formation in northeastern Alberta represents one of the most important hydrocarbon accumulations in the world with estimated more than 1.7 trillion barrels of oil in-place. Reservoir deposits are primarily associated with point bars and sandstone-filled channels. The reservoir is produced through steam assisted gravity drainage (SAGD), a very cost intensive operation that uses horizontal well pairs to extract bitumen. Successful SAGD relies on heat transfer through the reservoir from stem injection wells to horizontal producers at the base of the reservoir. Detailed knowledge of depositional facies, vertical and lateral distributions of potential stem-barriers (mud), net pay thickness and geometry of the reservoir are required for a successful reservoir development.

Marine and Petroleum Geology, Sep 1, 2012

Bulletin of Canadian Petroleum Geology, Dec 1, 2011

To optimize SAGD well-pair placement and improve thermal recovery operations, geochemical bitumen... more To optimize SAGD well-pair placement and improve thermal recovery operations, geochemical bitumen composition logs are used to identify barriers and baffles to fluid flow, which may compartmentalize McMurray Formation reservoirs in the Athabasca Oil Sands. SAGD steam chamber growth and cumulative steam oil ratios are sensitive to both vertical permeability and bitumen viscosity variations, which are commonly encountered in the oil sands reservoirs. In the McMurray Formation, tidally influenced meandering channel deposits are commonly vertically stacked, forming reservoir columns up to 80 m thick. In many instances, inclined heterolithic strata (IHS), consisting of interbedded sand and silt deposited on point bars, comprise barriers to vertical steam chamber growth at multiple horizons of a reservoir. Thus, the identification, characterization, and delineation of IHS intervals is a critical step for evaluating the reservoir development potential, and designing an optimal reservoir development strategy. While siltstone beds are routinely identified in cores and geophysical logs, thin siltstone beds that can act as a barrier to fluid flow are not discernible in seismic reflection data and have proven difficult to correlate between adjacent delineation wells. In this study, geochemical bitumen analysis is used to determine the integrity and continuity of siltstone beds within IHS in order to assess their potential impact on SAGD steam chamber growth. First, high-resolution molecular composition profiles are obtained from gas chromatography-mass spectrometry analyses of bitumen extracted from cores. The continuity of biodegradation-susceptible aromatic hydrocarbon concentrations measured through vertical profiles of a reservoir were used to determine if siltstone-prone intervals observed in log and core data acted as barriers or baffles to fluid flow over geological time. Integration of the bitumen molecular composition data with geological cross-sections fosters predictions of the lateral extent of the identified barriers. Furthermore, inferences about reservoir charging and in-reservoir fluid mixing histories are also made. Geochemical log data indicate that thickness of a heterogeneous low permeability interval is not necessarily the critical attribute of a barrier to fluid flow. Integration of both sedimentological information and bitumen geochemical data is useful for the identification of barriers and baffles to fluid flow in oil sand reservoirs. The method can be applied prior to positioning of SAGD well-pairs and thus could represent an important step for development planning of heterogeneous reservoirs.

AAPG Bulletin, Jul 1, 2011

The bitumen of the Lower Cretaceous McMurray Formation in Alberta arguably represents one of the ... more The bitumen of the Lower Cretaceous McMurray Formation in Alberta arguably represents one of the most important hydrocarbon accumulations in the world. In-situ development relies on heat transfer through the reservoir via horizontal steam injection wells placed 4 to 6 m (13-20 ft) above horizontal producers near the base of the sandstone reservoirs. Given this technology, understanding the distribution of the resource is paramount for a successful development program. Sedimentary facies provide a direct control on bitumen distribution and recovery. Most facies models developed to describe and predict sedimentary units of the McMurray Formation consider fluvial, estuarine, and/or deltaic depositional settings. In-situ development, however, requires a particularly high-resolution sedimentologic interpretation. High-quality three-dimensional seismic reflection data and extensive drill cores from acreage located approximately 50 km (31 mi) south of Fort McMurray provide important insights into the sedimentologic organization of reservoir and nonreservoir deposits in the upper one third (40 m [131 ft]) of the reservoir interval. Geomorphologic characteristics of the strata observed in seismic time slices reveal that a fluvial depositional setting was prevalent. Ichnologic and palynologic data, as well as sedimentary structures suggestive of tidal processes, indicate a marine influence in the upper

The Viewpoint and Amphitheatre outcrops near Ft. McKay, Alberta are visited frequently by geoscie... more The Viewpoint and Amphitheatre outcrops near Ft. McKay, Alberta are visited frequently by geoscience and engineering staff on oil-sands field seminars, but interpretation is usually restricted to the lateral extent of the outcrops themselves. This paper integrates outcrop with subsurface borehole data to (i) map and interpret the reservoir quality on a well-pad scale, which can be used to further refine SAGD geomodels to help with mapping the 3-D geometries and (ii) demonstrate utility of outcrops for interpreting geology from core data. Comprehensive descriptions of these two outcrops are provided by

Sedimentary Geology, Apr 1, 2016

Abstract Classical models developed for ancient fluvial point bars are based on the assumption th... more Abstract Classical models developed for ancient fluvial point bars are based on the assumption that meander bends invariably increase their radius as meander-bend apices migrate in a direction transverse to the channel-belt axis (i.e., meander bend expansion). However, many modern meandering rivers are also characterized by down-valley migration of the bend apex, a mechanism that takes place without a significant change in meander radius and wavelength. Downstream-migrating fluvial point bars (DMFPB) are the dominant architectural element of these types of meander belts. Yet they are poorly known from ancient fluvial-channel belts, since their disambiguation from expansional point bars often requires fully-3D perspectives. This study aims to review DMFPB deposits spanning in age from Devonian to Holocene, and to discuss their main architectural and sedimentological features from published outcrop, borehole and 3D-seismic datasets. Fluvial successions hosting DMFPB mainly accumulated in low accommodation conditions, where channel belts were affected by different degrees of morphological (e.g., valleys) or tectonic (e.g., axial drainage of shortening basins) confinement. In confined settings, bends migrate downstream along the erosion-resistant valley flanks and little or no floodplain deposits are preserved. Progressive floor aggradation (e.g., valley filling) allow meander belts with DMFPB to decrease their degree of confinement. In less confined settings, meander bends migrate downstream mainly after impinging against older, erosion-resistant channel fill mud. By contrast, tectonic confinement is commonly associated with uplifted alluvial plains that prevented meander-bend expansion, in turn triggering downstream translation. At the scale of individual point bars, translational morphodynamics promote the preservation of downstream-bar deposits, whereas the coarser-grained upstream and central beds are less frequently preserved. However, enhanced preservation of upstream-bar deposits can be controlled by aggradation at the scale of the entire meander belt. Despite their different preservation potential, the sedimentology of downstream-bar deposits is overall similar to that of expansional bars, since a downstream decrease in grain size and dominance of upbar-directed palaeoflows are observed in both cases. Bar-tail deposits are instead distinctive of DMFPB, specifically when channel-flow impinges at high angle against river outer banks. There, fine-grained counter-point bars or coarse-grained eddy-accretion deposits can accumulate. Channel belts dominated by DMFPB develop cross-sectional configurations featuring two main marginal trenches, commonly filled with bar tail deposits.

Both dune-trough (also known as dune-bottomset) mud deposits and muds in inclined heterolithic st... more Both dune-trough (also known as dune-bottomset) mud deposits and muds in inclined heterolithic stratification (IHS; Thomas et al., 1987) are deposited in the same depositional systems including fluvial, tidal, and tidally influenced fluvial systems. Although their geometries and structures are fundamentally different, these two deposits are hard to distinguish in core (Figure 1).