Abstract An integrated data set containing detailed three-dimensional ground-penetrating radar surveys, outcrop mapping, and both in situ and lab-based petrophysical measurements provides an unusually detailed foundation for simulating fluid flow through the three-dimensional permeability structure of a channel sandstone reservoir analog within a study volume 40 m x 20 m (130 ft x 60 ft) (in plan) and 15 m (45 ft) deep. Permeability (k) data (more than 1100 data points ranging from 0.5-300 md) are obtained from probe permeameter measurements made on core plugs collected from five vertical cliff-face transects and on slabbed drill-hole core from four, 14-m-deep (42-ft) holes drilled 10-20 m (30-60 ft) behind the outcrop. Analytical petrography and comparison of outcrop k values with those from drill-hole core show that weathering has caused a factor of 2 to 5 increase in cliff-face permeability with a significantly different univariate k distribution from that of the behind-the-outcrop drill-hole core. The permeability differences are accounted for by “correcting” the weathered cliff-face values to mimic the distribution of k values obtained behind the outcrop using an inverse transformation method. The field-based k data are integrated into two classes of three-dimensional, geostatistically generated, stochastic permeability models. One model type uses ground-penetrating radar data solely to define important bounding surfaces with sandstone permeability extrapolated directly from the k data. The other model type uses the ground-penetrating radar data to explicitly constrain a sandstone permeability structure and to define the geometry, thickness, and distribution of shale/mud-stone units. A series of two-phase fluid-flow simulations within 15 m x 15 m (45 ft x 45 ft) (in plan) by 10.8 m (35 ft) deep model domains, using grid blocks 1 m 2 (9 ft 2 ) (in plan) and 0.2 m (0.7 ft) thick, yield several conclusions. First, replacing the entire volume with a single k value computed with arithmetic, geometric, or harmonic mean of all k values in the volume yields a poor approximation of oil production computed using the original detailed, heterogeneous k structure. Second, in most cases upscaling using a vertically averaged geometric mean (as opposed to using arithmetic or harmonic means) provides a reasonable match to the oil production computed using the original detailed, heterogeneous k structure. Third, it is important to distinguish between fully continuous versus discontinuous shale unit geometries, and to be able to estimate angle of shale unit dip, when selecting methods for upscaling outcrop permeability values for use in reservoir simulators. Integrating three-dimensional ground-penetrating radar surveys with outcrop-based sedimentological and petrophysical data can provide the estimates of size, dip, continuity, and distribution of shale units needed at the scale of individual simulator grid blocks to help improve our approaches for deriving the upscaled k values used as input to production-scale reservoir simulators.

Abstract The latest Cretaceous to Eocene Difunta Group in the Parras, La Popa, and the southern part of the Sabinas Basins in the states of Coahuila and Nuevo León in northeast Mexico once occupied anextensive basin in the foreland to the Sierra Madre Oriental fold and thrust belt. The Difunta foreland basin records a complex history of initial Cretaceous deformation in the Sierra Madre Oriental and subsequent early Tertiary salt withdrawal in the region covered by the salt basin in the western part of the Gulf of Mexico. As a result of rapid facies transitions in the Difunta Group, stratigraphic correlation between the three structural basins is complex. Only one regionally extensive lithostratigraphic unit occurs in the Difunta Group, namely, the Maastrichtian Cañon del Tule Formation in the Parras Basin and the correlative Muerto Formation in La Popa Basin and the southern part of the Sabinas Basin. Detailed sedimentologic and sequence stratigraphic studies of the Cañon del Tule and Muerto formations have led to dramatic revisions in correlations in the Difunta Group. The Difunta Group is now subdivided into five informal “stratigraphic cycles” termed SC1, SC2, SC3, SC4, and SC5, each composed of marine mudstone and sandstone with overlying red fluvial mudstone. Stratigraphic cycles SC1 to SC3 were deposited in the latest Cretaceous in response to tectonic loading by encroaching thrust sheets in the Sierra Madre Oriental. In the southeastern Parras Basin, near the Sierra Madre Oriental frontal zone, the foredeep fill is at least 3677 m thick, thinning to 922 m, 150 km (structurally unrestored) to the north in the southern Sabinas Basin. Sediment dispersal was from west to east along the axis of the Difunta foredeep with a dissected volcanic arc provenance presumed to be the Guerrero composite terrane. Exceptionally high subsidence rates of >1 m/1000 years caused sediment to be “trapped” in the southern part of the foredeep, adjacent to the thrust belt, preventing early deltaic complexes in SC1 and SC2 from prograding eastward. The contemporary Mendez shale in the Tampico-Misantla foredeep, which was connected to the Parras–La Popa Basins across the Monterrey salient, represents a starved, underfilled equivalent of the Difunta foredeep to the southeast. In the distal northern part of the Difunta foredeep, in northern La Popa and southern Sabinas Basins, stratigraphic cycles are characterized by forced regression caused by limited subsidence. By the Paleocene and Eocene, thrusting in the Sierra Madre Oriental and accompanying foreland basin subsidence had ceased. In the region of the Parras Basin, no more sediment accumulated in the Difunta Group. In La Popa Basin and the southern part of the Sabinas Basin, which overlie the western extension of the Gulf of Mexico salt basin, growth of salt diapirs and associated salt withdrawal resulted in accumulation of more than 2300 m of sediment in structural “minibasins.” Large volumes of volcaniclastic detritus continued to be supplied from the west, filling the salt minibasins with fluvial and shallow-marine sediment. These Tertiary sequences represent cycles SC4 and SC5 in the Difunta Group. By the Paleocene, in the Tampico-Misantla portion of the Difunta foredeep, axially derived sands were deposited in the Chicontepec paleochannel. Only limited carbonate clastic input from the Sierra Madre Oriental highland was received in the Tampico-Misantla Basin in the Tertiary, and at no time did the Sierra Madre Oriental supply detritus to the Parras or La Popa Basins. Some time after the Eocene, probably in the early Oligocene, the region covered by the Difunta foredeep was deformed, uplifted, and eroded, leading to the present outcrop pattern of structural basins and highs. This episode of uplift resulted in large volumes of sediment being deposited in the western Gulf of Mexico Basin and led to substantial progradation of the northeast Mexican continental margin and establishment of a large, early Oligocene depocenter.

Abstract The Madre de Dios Basin of Bolivia represents two distinct phases of tectonic development that illustrate the linked stratigraphic responses to a changing basin style. The first phase associated with the Paleozoic is characterized as an intracratonic setting. The second, which began during the late Mesozoic and persists today, is the development of the Sub-Andean Foreland Basin. Hydrocarbons occur primarily within stratigraphic traps, potential reservoirs and seals are Paleozoic to Late Mesozoic in age. Paleozoic depositional environments identified from core indicate major changes in climatic conditions have occurred and include fluvial/deltaic, eolian dune, coastal sabkha, and shallow marine carbonate facies. A Late Devonian marine source rock with total organic carbon (TOC) content of up to 18% also occurs within the basin. Cretaceous age sediments contain an incised valley system of 10 to 15 kilometers in width and 300 meters in depth. Valley fill facies represent low sinuosity, braided fluvial systems grading upwards into estuarine muds. Terracing of the valley margin formed in response to multiple cut and fill episodes (baselevel fluctuations) of valley formation. Recurrent movements of basement involved fault blocks related to migration of the advancing forebulge, controlled the location and magnitude of valley incision and drainage incisement patterns. Large-scale variations in depositional environments, duration of geologic time (450 to 60 MY) represented by the stratigraphic section within a changing tectonic style, provides the Madre de Dios Basin as an example of the process to response interplay between tectonics, eustasy, climate and sediment supply.