Poster

Building a predictive model for sequence stratigraphic transitions and lateral facies changes in the Cretaceous Almond Formation, Wyoming

May 2019

DOI:10.1130/abs/2019AM-338617

Conference: AAPG Annual Convention and Exhibition, San Antonio, TX, May 19-22

Authors:

Joseph Phillips

Utah Valley University

Stephen Phillips

Brigham Young University

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Article

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Quantifying the Lateral Heterogeneity of Distal Submarine Lobe Deposits, Point Loma Formation, Calif...

November 2021 · The Depositional Record

Submarine fan deposits are volumetrically the largest sediment accumulations on Earth and host significant hydrocarbon reserves. Extensive research has documented the bed‐scale architecture of high sand‐to‐mud ratio, proximal and axial environments, which can have bed thicknesses of several metres; however less well‐understood are thin‐bedded turbidites, which are typically lower N:G and ... [Show full abstract] deposited in more distal environments. Conceptual models assume that lobe‐fringe‐to‐basin plain environments consist of tabular, sheet‐like beds that extend out continuously and predictably over long distances—up to several kilometres. Extensive lateral continuity, however, is not necessarily reflected in ancient outcrop analogues. This study seeks to apply a quantitative approach to the characterisation of thin‐bedded turbidites to assess the impact of multi‐scale heterogeneity on reservoir predictability. The sea‐cliff outcrop exposures of the Upper Cretaceous Point Loma Formation in San Diego, California, exhibit a wide range of bed thicknesses and stratigraphic architecture, which have been used to interpret an off‐axis‐to‐fringe depositional environment. The study area spans 700 m of laterally continuous outcrop, across which 10 correlated stratigraphic sections are used to quantify changes in metrics such as bed thickness, N:G, lithofacies proportions, etc. Results of this study demonstrate that thin sand beds experience both lateral facies changes and rapid thickness changes more frequently than conceptual models would predict. A single measure of lateral heterogeneity does not reflect the true architecture of sandstone beds, and significant information is lost when beds are correlated over ten to hundreds of metres. Sands are commonly deposited in irregular, “finger‐like”, planform geometries, which compounds at the lobe‐element scale and influences lateral lithofacies predictability. This study of the Point Loma Formation offers high‐resolution bed‐to‐element scale data, which may be used as inputs for reservoir models and horizontal facies predictions in both conventional and unconventional hydrocarbon reservoirs.

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Article

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Lateral facies variation in the lowermost Jurassic of the central Iberian Chain (NE Spain): Early di...

January 2002 · Acta Geologica Hispanica

A sedimentological analysis has been carried out in the uppermost Raethian-Sinemurian, Cortes de Tajuña, Lécera and Cuevas Labradas (lower part) Fms., in the outcrops of the Sierra de Arcos (central Iberian Chain, NE Spain). Three facies have been distinguished: gypsum-anhydrite with dolomitic intercalations, breccias (with evaporitic and dolomitic clasts) and massive dolomites. These facies were ... [Show full abstract] deposited in inner platform areas, ranging from shallow sabkha to intertidal flat environments. Breccias were originated by dissolution during the early stages of the diagenesis. The presence of evaporites reflects the development of supratidal areas, oversaturated in salts. Thick evaporites successions change laterally to breccias, showing a gradual environmental transition. Overall thickness variation in the uppermost Raethian-Hettangian units was controlled by local basin subsidence due to normal faulting, rather than late burial dissolution of evaporitic levels.

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Chapter

Meter-Scale Vertical and Lateral Facies Variability in a Sequence Stratigraphic Framework: Example f...

January 2019

A sedimentary bed is classically defined as a distinct layer of sedimentary rock that has a relatively uniform composition. Several outcrop-based studies have shown that facies within individual beds can vary laterally on a scale of around 100 m. As facies transitions are important criterions used as a proxy for the depositional environment and often to infer sequence stratigraphic trends in ... [Show full abstract] subsurface studies where data is limited to one-dimensional wells, this observed facies heterogeneity has implications for both paleoenvironmental studies and sequence stratigraphy. In this study, we investigate whether sedimentary and facies heterogeneities known to occur at the hundred meters scale are also present at the meter to tens of meters scale in a well-preserved facies mosaic deposited on a carbonate ramp (Wadi Naqab, Izhara Formation, Lower Bajocian, northern UAE), where a robust, outcrop-based sequence stratigraphic framework exists. A bed set was logged and mapped across a 120 m long curving cliff face; combined with thin section analysis, the data allowed the reconstruction and quantification of facies heterogeneity at this location. Results reveal a large amount of lateral facies transitions at the meter scale. Lithofacies types have a probability of less than 70% of being laterally continuous over 12 to 18 meters, representing the highest amount of lateral facies heterogeneity so far reported in an ancient example. The case study reveals intra-bed facies transitioning attributed to spatially heterogeneous biogenic carbonate production as well as to syndepositional homogenizing and sieving processes occurring within shallow-marine depositional environments in ancient as well as in modern analogous systems. A series of continuous hardgrounds, previously interpreted as flooding and exposure surfaces, provide an independent sequence stratigraphic framework that demonstrate that the existence of small-scale lateral facies heterogeneities complicates interpretation of the vertical stacking pattern of facies. This confirms that the best practice is to limit sequence stratigraphic interpretations based on facies trends to larger stacking patterns (>10 meters). Meter-scale vertical patterns in carbonates often do not represent a proxy for base level changes, as illustrated in our study; therefore, fine-scaled, high-resolution sequence stratigraphy or lateral correlations are not attainable in carbonate sequences based on lithostratigraphy.

Investigation of Lateral Facies Variation and its Impact on Reservoir Quality Distribution in Comple...

January 2023 · SSRN Electronic Journal