Clinothems are seaward-dipping beds which are deposited during the progradation of delta-front mouth bars. Measurements taken from clinothems in the field and from geospatially constrained, photo-realistic virtual outcrops were used to record clinothem dip, maximum bed thickness, and bed thickness every 10 m along a series of depositional-dip-oriented profiles from two ancient river-dominated delta successions which crop out in central Utah, USA. These data show systematic changes in bed dip and bed thinning which highlight discrete packaging of the beds into bedsets, interpreted to represent the progradation of stream mouth bars in the delta front. Individual bedsets are characterized by a progressive steepening of beds coupled with a more rapid thinning.Systematic collection of 2800 locations along 73 separate clinothems from the Panther Tongue Sandstone Member and parasequence If from the Ferron Sandstone were used to study the relationship between bed thickness, dip, and decay gradient parameter (tau), which describes the down-dip bed thinning. Clinothems in the Panther Tongue are much longer and more gently dipping than the clinothems in the Ferron Sandstone. In both systems, beds can be clustered into groups (bedsets) which show a systematic decrease in tau-values and an increase in dip angle. Boundaries between the groups are defined by a sudden increase in tau-values and a concurrent decrease in dip angle. These bedsets are interpreted to represent individual stream mouth bars which amalgamate to form mouth bar complexes within the delta-front sand bodies. The use of virtual outcrops was essential for the collection of the large volumes of thickness data and the recognition of very subtle (< 1 degrees) changes in dip angle which have made these interpretations possible.

This study presents a methodology for the quantitative description of small-scale delta clinothems. The quantitative bed-data analysis is based on three-dimensional virtual outcrop models generated by ground-based laser scanning (Light Detection and Ranging). A large number of clinothem bed measurements have been collected from the ancient forced regressive delta system of the Panther Tongue that crops out in Utah, USA. In river-dominated marginal marine environments, clinothems separated by clinoform surfaces represent the former position of the delta front as it prograded. Systematic collection of data from virtual outcrop models has allowed for accurate, spatially constrained measurement of individual bed thicknesses and the compilation of a detailed database on clinothems and associated clinoform geometries. Measurement locations were selected so that each measurement was 10 m down depositional dip from the previous one. The study area covers 5 km2 within which 2376 measurements were made from 50 separate clinothems in 320 different positions within the virtual outcrop. A bed taper parameter permitted the thinning of the clinothems to be described as a single number and thus allowed relative comparison between beds. Combined measurements were also used to calculate the average dip angle of the clinothems. Analysis of the vertical and lateral stacking of the clinothems has revealed a series of stratigraphic cycles which are termed bedsets (stream-mouth bars). The surfaces that bound the bedsets are unremarkable and it is unlikely that their significance would be recognized without this style of detailed analysis. A cyclic depositional pattern, interpreted as related to autocyclic processes and compensational stacking of mouth bars, is proposed as the origin of these packages. Mapped length/thickness trends constrain the spread of these variables, and can be used to constrain subsurface models of analogous hydrocarbon reservoirs.

This paper discusses the application of laser scanning and photo‐realistic modelling to aid the study of geological outcrops, using two examples from central and eastern Utah, USA, which are analogues to subsurface hydrocarbon fields. Terrestrial laser scanning point clouds were triangulated to obtain high‐resolution surface representations, which were combined with semi‐metric imagery to give texture‐mapped photo‐realistic models of the outcrops. Such models provide the basis for geological interpretation and were used to reconstruct the geometries of layers over the extent of the study area. The digitised geological layers were in turn used to build geocellular volumes that capture the properties of the geology. These models were built in subsurface reservoir modelling software and were used to simulate the flow of fluids through the reservoir analogue. In this way, the spatial information provided significantly more detailed quantitative data and greatly improved the outcrop studies compared to traditional field techniques.

The Eocene Roda Sandstone of the Spanish Pyrenees is comprised of two coeval coarse-grained delta systems which share correlatable surfaces but show a markedly different internal facies architecture. The two deltas developed contemporaneously with the differences in internal architecture attributed to basin morphology and the role of two, distinct sediment sources, while the correlatability of the larger-scale packages indicates an external, allocyclic control. As such the Roda Sandstone provides the possibility to address the relative roles of different parameters known to interact and control stratal architecture.

Subsurface reservoir models are typically limited by a lack of spatially accurate geometric data on bedform architecture and geometry. These factors are key controls on fluid flow. Outcrop analogs have long been used as a source of such data, but the capture of sufficiently precise outcrop data is a challenge. The study presented in this article used highly accurate geometrical digital geological outcrop data collected using ground-based laser scanning (light detection and ranging [LIDAR]) to build and test three-dimensional geocellular models of deltaic reservoir analogs.Two well-exposed ancient river-dominated delta systems, the Panther Tongue and the Ferron Sandstone Member, which both crop out in central Utah, were digitally mapped to precisely recreate their clinothem and clinoform geometries in geocellular reservoir modeling software. Such clinoforms are commonly draped with low-permeability mudstones that produce reservoir heterogeneity by subdividing the deltaic sand body into a series of dipping sandstone beds (clinothems). A key aspect of the modeling was to accurately capture these geometries and their effect on simulated fluid flow.Portions of the two deltaic systems were dynamically analyzed in a reservoir modeling software by simulating production in 41 models. These models tested a range of mudstone barrier continuities and permeabilities. Results quantify how the continuation of the heterogeneities governed the production rate and recovery factor in the Panther Tongue models. Mudstone permeability values were more important in the Ferron Sandstone models with steeper dipping and closer spaced clinothems, although production was still influenced by the continuation of the heterogeneities.

Advances in data capture and computer technology have made possible the collection of three-dimensional, high-resolution, digital geological data from outcrop analogs. This paper presents new methodologies for the acquisition and utilization of three-dimensional information generated by ground-based laser scanning (lidar) of outcrops. A complete workflow is documented-from outcrop selection through data collection, processing and building of virtual outcrops to geological interpretation and the building of geocellular models using an industry-standard, reservoir-modeling software. Data sets from the Roda Sandstone in the Spanish Pyrenees and the Grabens region of Canyonlands National Park, Utah, USA, are used to illustrate the application of the workflow to sedimentary and structural problems at a reservoir scale.Subsurface reservoir models are limited by available geological data. Outcrop analogs from comparable systems, such as the Roda Sandstone and the Grabens, are commonly used to provide additional input to models of the subsurface. Outcrop geocellular models can be analyzed both statically and dynamically, wherein static examination involves visual inspection and the extraction of quantitative data on body geometry, and dynamic investigation involves the simulation of fluid flow through the analog model.The work presented in this study demonstrates the utility of lidar as a data collection technique for the building of more accurate outcrop-based geocellular models. The aim of this publication is to present the first documentation of a complete workflow that extends from outcrop selection to model investigation through the presentation of two worked data sets.