Browsing by Subject "Facies"
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Item Characterizing reservoir quality for geologic storage of CO2 : a case study from the Lower Miocene shore zone at Matagorda Bay, Texas(2021-05-10) Hull, Harry Lejeune; Meckel, Timothy AshworthThe geologic storage of anthropogenic CO₂ through Carbon Capture, Utilization, and Storage (CCUS) is necessary to reduce the emissions produced as a biproduct of fossil fuel combustion. This process of injecting CO₂ into the subsurface is known as carbon sequestration and requires the assessment of geologic reservoirs. Depositional processes and the resulting facies and stratigraphic architectures have great influence over reservoir volumetrics and behavior. The objective of this study is to constrain the depositional controls on storage capacity. A subsurface Lower Miocene 2 strandplain/barrier bar complex of the Texas Gulf Coast at Matagorda bay is interpreted and modeled using well data and 3D seismic. These data reveal the presence of a major shore zone that experienced initial progradation through the late highstand and into the lowstand before later retrogradation. The LM2 is then capped by a thick regional shale. A stratigraphic framework is built that captures these changes in shoreline position at both the systems tract and parasequences level. Sediments were strike fed and wave-dominated processes are apparent. Petrophysical properties of this region including porosity are modeled from with machine learning from log data. Machine learning to predict porosity is carried out using a random forest regression in which porosity is a function of lithology and depth. Finally, a 3D reservoir model is built integrating the stratigraphic, facies, and petrophysical properties. Static storage capacity estimates and storage capacity maps are created from the 3D model. Storage capacity is observed to occur at a strike parallel geometry. This “axis” of highest storage capacity tracts with the position of the shore zone in vertical succession highlighting a dependence on the balance between the generation of accommodation and sediment supply. At a higher resolution storage capacity is observed highest within the foreshore where beach ridges are interpreted from seismic stratal slices. High wave energy processes at this position in the shoreline profile are known to create well sorted and therefore highly porous sandstones. Storage capacity is then a direct function of the high wave energy paleo-depositional processes occurring at the shorelineItem Controls on Oligocene-Miocene carbonate shelf evolution, offshore East Java, Indonesia : insights from architecture, facies, and seismic geomorphology(2018-12) Fifariz, Reynaldy; Janson, Xavier; Kerans, C. (Charles), 1954-; Fulthorpe, Craig S; Steel, Ronald J; Cloos, Mark; Sapiie, BenyaminCarbonates were extensively deposited in the Oligocene–Miocene and are now prolific hydrocarbon reservoirs in the Southeast Asia region. Hydrocarbon exploration and production activities have resulted in extensive availability of subsurface data from this stratigraphic interval. During the Oligocene–Miocene, carbonate shelves in this region have evolved and show spatial-temporal variations in term of architecture and facies. Despite the economic importance, data availability, and complexity of the region, little effort has been made to decipher the dominant controls on carbonate shelves evolution. This research utilized 24 wells and 1,300 km² of 3D seismic data from offshore East Java, Indonesia to study the Oligocene–Early Miocene Kujung Formation and the Late Miocene Wonocolo Formation. Depositional settings of the Kujung Formation have evolved from mixed-siliciclastic-carbonate shelf in the Rupelian–Chattian to carbonate-buildups shelf in the Aquitanian. The change happened at around the Oligocene-Miocene boundary at 23 Ma. Three-dimensional seismic geomorphology techniques were utilized to further characterize the Kujung and Wonocolo Formations. Carbonate shelves in the study area have evolved from having west-southwest – east-northeast elongated, circular-ovoid, to polygonal carbonate buildups in the Early Miocene to being dominated by north-south elongated flat-topped carbonate platforms in the Late Miocene. Hydrocarbons have been produced mainly from the Kujung Formation buildup-core. On the basis of well data, off-buildup carbonate-dominated strata are considered as an upside potential with indications of gas accumulation. Volumetric calculations demonstrated encouraging results for this interval, which could be developed as part of an integrated field development strategy. Tectonically inherited antecedent topography, siliciclastic sediment routing, and localized differential tectonic subsidence are the dominant controls on platform-, basin-, to regional-scale spatial variation in distribution of siliciclastic and carbonate sediments, and the resulting architecture and facies on carbonate shelves during the Oligocene–Early Miocene. Change in the global sea-level fluctuation patterns seems to have caused the temporal variation represented in extensive carbonate buildups development starting in the Early Miocene. These controls could even override the influence of regional climatic change around the Oligocene-Miocene boundary. In the Late Miocene, intensifying compressional tectonic events have resulted in decreased accommodation on the carbonate shelves. Development of Indonesian through-flow during this period have strongly influenced the oceanic circulation resulted in extensive development of north-south elongated flat-topped carbonate platforms. Ultimately, this research aims to provide valuable insights to better explain controls on Oligocene-Miocene carbonate shelf evolution and to better predict architecture, facies, geometry, and distribution of carbonate reservoirs situated in a tectonically active region. This research utilized 24 wells and 1,300 km2 of 3D seismic data from offshore East Java, Indonesia to study the Oligocene–Early Miocene Kujung Formation and the Late Miocene Wonocolo Formation. Depositional settings of the Kujung Formation have evolved from mixed-siliciclastic-carbonate shelf in the Rupelian–Chattian to carbonate-buildups shelf in the Aquitanian. The change happened at around the Oligocene-Miocene boundary at 23 Ma. Three-dimensional seismic geomorphology techniques were utilized to further characterize the Kujung and Wonocolo Formations. Carbonate shelves in the study area have evolved from having west-southwest – east-northeast elongated, circular-ovoid, to polygonal carbonate buildups in the Early Miocene to being dominated by north-south elongated flat-topped carbonate platforms in the Late Miocene. Hydrocarbons have been produced mainly from the Kujung Formation buildup-core. On the basis of well data, off-buildup carbonate-dominated strata are considered as an upside potential with indications of gas accumulation. Volumetric calculations demonstrated encouraging results for this interval, which could be developed as part of an integrated field development strategy. Tectonically inherited antecedent topography, siliciclastic sediment routing, and localized differential tectonic subsidence are the dominant controls on platform-, basin-, to regional-scale spatial variation in distribution of siliciclastic and carbonate sediments, and the resulting architecture and facies on carbonate shelves during the Oligocene–Early Miocene. Change in the global sea-level fluctuation patterns seems to have caused the temporal variation represented in extensive carbonate buildups development starting in the Early Miocene. These controls could even override the influence of regional climatic change around the Oligocene-Miocene boundary. In the Late Miocene, intensifying compressional tectonic events have resulted in decreased accommodation on the carbonate shelves. Development of Indonesian through-flow during this period have strongly influenced the oceanic circulation resulted in extensive development of north-south elongated flat-topped carbonate platforms. Ultimately, this research aims to provide valuable insights to better explain controls on Oligocene-Miocene carbonate shelf evolution and to better predict architecture, facies, geometry, and distribution of carbonate reservoirs situated in a tectonically active region.Item Depositional systems and natural resources of the middle Eocene Yegua Formation, south and central Texas coastal plain(1981) Van Dalen, Stephen Craig; Not availableA regional investigation of the Yegua Formation, using both surface and subsurface data, permits delineation of two genetic units beneath the south and central Texas coastal plain. The lower pro-gradational Yegua unit is composed of a series of wave-dominated delta systems. The principal deltaic complex, the Falcon delta, is located in Webb County and is believed related to the deposition of an ancestral Rio Grande. Facies within the delta include: channel-fill/channel mouth bar; coastal barrier; lagoonal/marsh/floodbasin; prodelta; and transgressive/destructional. The upper Yegua unit consists of stacked barrier bar and lagoonal systems in south Texas. This unit was deposited following abandonment of the Falcon delta, upon avulsion of the Rio Grande and its shift into northeastern Mexico. As the delta foundered, it was replaced by a barrier system supplied with strike-fed sediments from the Mexican delta located to the south. In central coastal Texas, both the upper and lower Yegua consist of a series of small wave-dominated to lobate deltas. The Yegua Formation contains important oil and gas reservoirs in this area. Most production is from the upper genetic unit. Hydrocarbons are accumulated along a trend between the barrier bar and lagoonal systems, where minor structural features combine with pinchouts of barrier sands to provide stratigraphic traps. Another important area of production is along the Mirando-Provident City fault system, where faulted coastal barrier and deltaic sands serve as reservoirs. Because of highly mineralized ground water, the Yegua Formation is not an important aquifer. Commercial deposits of lignite or sedimentary uranium have not been recognized within the study area and sedimentological analysis indicates that discovery of these deposits is very unlikelyItem Diatremes(2009-03) Barker, Daniel S.Item Facies variability in deep water channel-to-lobe transition zone : Jurassic Los Molles Formation, Neuquen Basin, Argentina(2014-05) Tudor, Eugen Petrut; Steel, R. J.; Olariu, CornelThis study focuses on the facies changes from the lower slope to toe-of-slope to basin floor over a 10 km outcrop belt, in down-dip and oblique-strike directions to the basin margin. The Jurassic Los Molles Formation in Neuquen Basin, Argentina represents the slope and basin floor of basin margin clinoforms, coeval with the shallow water and fluvial deposits named Las Lajas and Challaco formations respectively. The shallow and deep water deposits are diachronously linked in an Early-Mid Jurassic source-to-sink system developed in a back-arc basin during the incipient development of the Andes Mountains. Satellite images, high resolution panorama pictures and measured sections were used to correlate and interpret the spatial variability and overall geometry of the base of slope to basin floor units. The observations of this study refine the model for the channel-to-lobe transition zone with increase recognition and quantification of facies and architecture variability. The Los Molles basin margin was coarse grained and was ideal to observe changes in the geometry and depositional facies of channel-to-lobe deposits from updip to downdip continuous over an 8 km outcrop belt. The described channel-to-lobe transition zone clearly shows a downdip change in bed boundaries from dominantly erosive to non-erosional (bypass) to depositional and with a range of distinct facies changes. In the transition zone the sand to shale ratio is high (N:G: 65-70 %), with gutter casts and deep scours, with a high degree of amalgamation, gravel lags, mud rip-up clasts and laterally migrating beds. Within the same depositional unit (deep water lobe), at the base of the slope, the dominant sandstone beds change from amalgamated structureless and normal graded sandstone beds in the channelized lobe axis to parallel laminated and normally graded in the channelized lobe off-axis areas. Similar facies changes have been observed along proximal to distal direction. The lateral change of the dominant structures in the beds indicates changes in the flow regime and depositional style.Item Integrated core, well log, and seismic interpretation of Albian patch reefs in Maverick Basin, SW Texas(2008) Aconcha, Enzo Sener; Kerans, C. (Charles), 1954-The Albian Glen Rose Formation has been well known as a shallow shelf carbonate with common patch reef development along the interface between the Comanche Shelf and the Maverick Basin. Stratigraphic analysis of 75 well logs and 7 seismic stratal slices formed the basic data for interpreting the Lower Glen Rose sequence framework and paleogeographic setting. The Lower Glen Rose units record the HST of sequence 6 and all of sequence 7. Patch reefs were found in the TST, near the MFS, and the HST of sequence 7, with three distinct reef levels found throughout units 2-4. Buildups in unit 2 change from transgressive isolated buildups into a flat biostrome during progressive onlap. Unit 3 buildups record a landward shift relative to the biostrome of unit 2, as shown on well logs and are coincident with the sequence 7 MFS. The third and uppermost buildup level is found in unit 4, in the late highstand of sequence 7. This unit shows a distinct seaward shift of the patch reefs, relative to unit 3, consistent with the highstand interpretation. Detailed examination of facies in the two cores available for study indicates that the patch reefs formed during shoaling of the shelf. These patch reefs are characterized by a low API GR value (<20 GAPInorm) and strong negative seismic amplitudes. Off-reef deposits correlate with a higher, variable gamma-ray response (>20 GAPInorm) and positive seismic amplitudes. The patch reefs are proven hydrocarbon reservoirs with gas potential concentrated in units 2 and 4. Geomorphometric analysis based on seismic stratal slices of more than 30 buildups from unit 4 determined that these are domal features with a distinct NNW-SSE elongation and steeper SW flanks. Asymmetry of the patch reefs may be the result of NW-directed far-field paleo-currents and NNE-directed, wind-driven paleo-waves. Independently of the size scale, the elongation axis of buildups is 1.5-2.5 times larger than its perpendicular direction. Results imply best reservoir facies in the SW side of the Lower Glen Rose patch reefsItem Integration of facies models in reservoir simulation(2010-12) Chang, Lin; Fisher, W. L. (William Lawrence), 1932-; Steel, Ronald; Torres-verdin, CarlosThe primary controls on subsurface reservoir heterogeneities and fluid flow characteristics are sedimentary facies architecture and petrophysical rock fabric distribution in clastic reservoirs and in carbonate reservoirs, respectively. Facies models are critical and fundamental for summarizing facies and facies architecture in data-rich areas. Facies models also assist in predicting the spatial architectural trend of sedimentary facies in other areas where subsurface information is lacking. The method for transferring geological information from different facies models into digital data and then generating associated numerical models is called facies modeling or geological modeling. Facies modeling is also vital to reservoir simulation and reservoir characterization analysis. By extensively studying and reviewing the relevant research in the published literature, this report identifies and analyzes the best and most detailed geologic data that can be used in facies modeling, and the most current geostatistical and stochastic methods applicable to facies modeling. Through intensive study of recent literature, the author (1) summarizes the basic concepts and their applications to facies and facies models, and discusses a variety of numerical modeling methods, including geostatistics and stochastic facies modeling, such as variogram-based geostatistics modeling, object-based stochastic modeling, and multiple-point geostatistics modeling; and (2) recognizes that the most effective way to characterize reservoir is to integrate data from multiple sources, such as well data, outcrop data, modern analogs, and seismic interpretation. Detailed and more accurate parameters using in facies modeling, including grain size, grain type, grain sorting, sedimentary structures, and diagenesis, are gained through this multidisciplinary analysis. The report concludes that facies and facies models are scale dependent, and that attention should be paid to scale-related issues in order to choose appropriate methods and parameters to meet facies modeling requirements.Item Reservoir characterization and sequence stratigraphy of Permian San Andres platform carbonates, Fullerton Field, Permian Basin, West Texas(2010-05) Helbert, Dana Kristin; Kerans, C. (Charles), 1954-; Ruppel, Stephen C.; Fisher, William L.The San Andres Formation (Permian, Guadalupian) is the most prolific oil reservoir in the Permian basin. However, despite more than 60 years of production, an estimated 70% of the original oil in place remains. Recovery of this huge resource requires a better understanding of facies and reservoir framework, which, in turn, must be accomplished using a rock-based reservoir characterization process. This high resolution correlation method is essential for understanding the complex heterogeneities found in shallow water platform carbonates. Steps in the construction of a rock-based reservoir model in the Fullerton San Andres Unit (FSAU) included (1) defining depositional facies and primary facies groups; (2) creating an outcrop depositional model; (3) integrating facies descriptions with gamma-ray and porosity log data; (3) defining field-wide high frequency sequences based on wireline logs and cycle stacking patterns; (4) developing a sequence-based reservoir framework and 3-dimensional reservoir architecture; (5) defining porosity and permeability relationships for facies groups based on rock fabric characteristics. In Fullerton Field, the San Andres Formation comprises high frequency cycles of upward shoaling shallow-marine carbonates. Studies of nine cores (1730 ft) in FSAU reveal four peritidal and five shallow subtidal depositional facies based on texture, fossil assemblages, and sedimentary structures. Peritidal facies are dominantly laminated carbonate mudstones, interpreted as deposited on an intermittently exposed tidal flat. Shallow subtidal facies are peloid and mollusk dominated wackestones and packstones, interpreted as deposited in a shallow protected lagoon. Cycle stacking patterns indicate four complete upward shallowing high frequency sequences. Comparison of high frequency sequences between cored wells shows a high degree of similarity in the overall generalized vertical sequence, especially in the proportions of peritidal and subtidal components within each sequence. Three-dimensional reservoir characterization, using 132 gamma ray and porosity logs, reveals that depositional sequences are largely flat-lying with local topographic variation identified as the fundamental influence on lateral facies distribution within the reservoir section. Integration of core and petrophysical data from surrounding fields places FSAU in the larger sequence stratigraphic framework of the Central Basin Platform. The regional depositional sequence formed a series of depositional environments ranging from intermittently exposed to open marine. San Andres facies developed during south-easterly progradation of shallow water tidal flat and sabkha sediments over a deeper open marine shelf.Item Rock classification from conventional well logs in hydrocarbon-bearing shale(2011-12) Popielski, Andrew Christopher; Torres-Verdín, Carlos; Balhoff, MatthewThis thesis introduces a rock typing method for application in shale gas reservoirs using conventional well logs and core data. Shale gas reservoirs are known to be highly heterogeneous and often require new or modified petrophysical techniques for accurate reservoir evaluation. In the past, petrophysical description of shale gas reservoirs with well logs has been focused to quantifying rock composition and organic-matter concentration. These solutions often require many assumptions and ad-hoc correlations where the interpretation becomes a core matching exercise. Scale effects on measurements are typically neglected in core matching. Rock typing in shale gas provides an alternative description by segmenting the reservoir into petrophysically-similar groups with k-means cluster analysis which can then be used for ranking and detailed analysis of depth zones favorable for production. A synthetic example illustrates the rock typing method for an idealized sequence of beds penetrated by a vertical well. Results and analysis from the synthetic example show that rock types from inverted log properties correctly identify the most organic-rich model types better than rock types detected from well logs in thin beds. Also, estimated kerogen concentration is shown to be most reliable in an under-determined problem. Field cases in the Barnett and Haynesville shale gas plays show the importance of core data for supplementing well logs and identifying correlations for desirable reservoir properties (kerogen/TOC concentration, gas saturation, and porosity). Qualitative rock classes are formed and verified using inverted estimates of kerogen concentration as a rock-quality metric. Inverted log properties identify 40% more of a high-kerogen rock type over well-log based rock types in the Barnett formation. A case in the Haynesville formation suggests the possibility of identifying depositional environments as a result of rock attributes that produce distinct groupings from k-means cluster analysis with well logs. Core data and inversion results indicate homogeneity in the Haynesville formation case. However, the distributions of rock types show a 50% occurrence between two rock types over 90 ft vertical-extent of reservoir. Rock types suggest vertical distributions that exhibit similar rock attributes with characteristic properties (porosity, organic concentration and maturity, and gas saturation). This method does not directly quantify reservoir parameters and would not serve the purpose of quantifying gas-in-place. Rock typing in shale gas with conventional well logs forms qualitative rock classes which can be used to calculate net-to-gross, validate conventional interpretation methods, perform well-to-well correlations, and establish facies distributions for integrated reservoir modeling in hydrocarbon-bearing shale.Item Seismic chronostratigraphy for reservoir characterization : modeling and applications(2017-05) He, Yawen; Kerans, C. (Charles), 1954-; Zeng, Hongliu, 1957-; Fisher, William; Fomel, Sergey; Janson, XavierThe assumption of the chronostratigraphic significance of seismic reflections serves as a fundamental premise in interpreting stratigraphy from seismic images. This hypothesis proposed in 1977 was initially applied to delineate depositional sequences as the basic interpretive unit, and then to reconstruct Wheeler Diagram and regional sea level curves. After a further comparison against with global eustatic events, these regional curves can further facilitate predicting the age, distribution, and facies of depositional sequence before drilling in a seismic-covered area during petroleum exploration. With a boom in reservoir-level seismic applications, for obtaining significant high frequency sequence (HFS) surfaces as the bounding surfaces in static reservoir model construction, this fundamental assumption was inevitably extended to characterize HFS and even high-frequency cycles (HFC) during seismic reservoir characterization. For an ultimate improvement in constructing reservoir-bounding surfaces, the author targeted at evaluating the validity of this fundamental assumption as applied to high-order seismic stratigraphy. The author conducted the entire project via the forward seismic modeling upon geologic models with known chronostratigraphic relationship. Besides, these input models carefully honor the reservoir geology for meaningful discussions on (1) shallow marine siliciclastic reservoirs in Starfak Field, GoM, (2) shallow-water mixed carbonate/clastic Upper San Andres-Grayburg reservoirs in Permian Basin, and (3) shallow-water carbonate Abo shelf margin-Clear Fork platform in Permian Basin. This study has achieved three-fold contributions. On the aspect of realistic geocellular, property and seismic modeling at the reservoir scale, the author integrated high-resolution sequence stratigraphic framework, published 3D depositional model, intra-facies heterogeneity in 3D modeling to selectively apply advanced geostatistical methods to model hierarchical heterogeneity. Subsequently, the author proposed an evaluation scheme with a defined parameter ('time-correlation error/TCE') to assess HFS-scale reservoir-bounding surfaces. These assessments revealed an interactive influence from (1) stratal geometry, (2) lateral lithofacies variation, (3) lithofacies-sonic velocity relationship in pure- versus mixed-lithology successions, (4) intra-facies heterogeneity, and (5) seismic frequency. Finally, based on these forward modeling results, the author proposed a decision tree to determine valid interpretation strategy in seismic chronostratigraphic correlation in scenarios with geoscientists’ expert knowledge and recommended an attribute-driven volumetric picking scheme to improve published algorithms for scenarios without prior knowledge.Item Sequence stratigraphic analysis of marginal marine sabkha facies : Entrada Sandstone, Four Corners region(2010-08) Makechnie, Glenn Kenneth; Kocurek, Gary; Mohrig, Davis; Steel, RonaldThe Middle Jurassic Entrada Sandstone of the Four Corners region, USA, is composed predominantly of very fine-grained, red, silty sandstone with poorly defined sedimentary structures. The origin of this facies is enigmatic, even though it is common both on the Colorado Plateau and globally, and is spatially situated between deposits recording unambiguous marine and aeolian environments. Eleven sections were measured along an 85 km transect from the Blanding Basin in southeastern Utah to the San Juan Basin in northwestern New Mexico. Outcrop and laboratory analyses distinguish eight facies: (1) silty shale, (2) shallow subaqueous reworked, fine- to medium-grained sandstone, (3) brecciated, very fine-grained sandstone, (4) crinkly laminated, very fine-grained sandstone with preserved wind ripples and abundant silty laminae, (5) weakly laminated, fine-grained sandstone with occasional silty laminae, (6) planar-laminated, fine-grained, wind-rippled sandstone, (7) cross-stratified, fine- to medium-grained aeolian cross-stratified sandstone, and (8) micritic limestone. Lateral and vertical relationships of these facies show a proximal to distal transition from cross-bedded wind-lain facies to loess-dominated sabkha facies with increasing abundance of water-lain facies basinward. The well known Todilto Limestone (facies 8) is situated stratigraphically below loess-dominated sabkha facies (facies 4 and 5) within the Entrada Sandstone, reinforcing previous interpretations that the unit represents a catastrophic flooding event and not a local groundwater flux.