Frontier Formation Research Articles

Productive, Low-Contrast (Resistivity) Frontier Formation Sandstones, Southwestern Wyoming: ABSTRACT

Productive, Low-Contrast (Resistivity) Frontier Formation Sandstones, Southwestern Wyoming: ABSTRACT

Provenance, Source Terrain Evolution, and Depositional Constraints on Foreland Basin Sequences: Upper Cretaceous Frontier Formation, North-Central Wyoming: ABSTRACT

Provenance, Source Terrain Evolution, and Depositional Constraints on Foreland Basin Sequences: Upper Cretaceous Frontier Formation, North-Central Wyoming: ABSTRACT

Madden Deep Unit of the Wind River Basin: A New Frontier Formation Play?

The Madden Deep unit, located in the Wind River basin of central Wyoming, has been a source of natural gas production from Upper Cretaceous and Lower Tertiary formations. Drilling in excess of 24,000 ft occurred during the mid-1980s and early 1990s to explore for and develop Paleozoic gas potential. These well bores penetrated the Upper Cretaceous Frontier Formation at depths below 20,000 ft. Open-hole logs, cores, and drilling cuttings suggest a significant gas accumulation within the Frontier. The Frontier Formation represents a series of coarsening-upward, shallow-marine sequences deposited as a seaward-stepping system along the Western Cretaceous Seaway margin. In Madden field, the fifth bench of the Frontier contains traditional facies from foreshore/beach, to upper and lower shoreface, to offshore regimes. Common to deposites elsewhere, the best reservoirs are found in the foreshore/beach settings at the top of the bench. Production is not related to easily understood porosity regimes; primary intergranular porosity is virtually nonexistent. An overpressured reservoir with numerous vertical/subvertical fractures accounts for production. Microfractures and megafractures, up to 10 mm across, provide permeabilities that exceed 1 d. Fractures are partly filled by abundant quartz and minor calcite. Mineralization would allow singificant reservoir pressure drawdown without reducing aperture width. Majormore » fractures apparently strike west-northwest, and such orientation data may permit a horizontal drilling venture when technology is capable of surviving such deep, overpressured, and high-temperature environments.« less

Influence of Provenance and Burial History on Diagenesis of Lower Cretaceous Frontier Formation Sandstones, Green River Basin, Wyoming

ABSTRACT The Upper Cretaceous Frontier Formation on the Moxa Arch in the western Green River Basin, Wyoming, has had a varied diagenetic history that was controlled in part by differences in composition of detrital framework grains and in burial history. Petrographic examination of 247 thin sections from 13 cores from the south-plunging arch and adjacent deep basin is the basis for diagenetic investigation of sandstones ranging in depth from 2 km to almost 5 km. Major diagenetic events were (1) mechanical compaction by grain rearrangement and deformation of ductile grains, (2) formation of illite and mixed-layer illite-smectite rims, (3) precipitation of quartz overgrowths, (4) precipitation of calcite cement, (5) generation of secondary porosity by dissolution of feldspar, chert, biotite, and mudstone grains and calcite cement, (6) precipitation of kaolinite in primary and secondary pores, and (7) chemical compaction by intergranular pressure solution and stylolitization and additional precipitation of quartz cement. The northern and southern ends of the Moxa Arch differ in the magnitude of each of these diagenetic events. Provenance differences caused more abundant ductile rock fragments and feldspar to be deposited at the northern end of the Moxa Arch. As a result, Frontier sandstones from the northern Moxa Arch underwent more extensive mechanical compaction. In addition, feldspar dissolution and albitization buffered acid-rich basinal fluids at the northern end, resulting in greater development of secondary porosity and precipitation of calcite cement than at the southern end. Deeply buried sandstones at the southern end of the arch and in the basin contain the most abundant quartz cement because intergranular pressure solution and stylolitization liberated silica for overgrowths.

Influence of Rock Heterogeneities on Fracture Geometry in the Green River Basin

Summary Constant-height models, in the absence of significant barrier stresses, frequently overpredict fracture half-lengths. This has been a problem in the fracture design of the Frontier and Dakota formations in the Greater Green River basin. Both formations often experience unlimited fracture-height growth as a result of a lack of barrier-stress contrast. This paper presents some of the implications of uncontained fracture-height growth in these formations on fracture design through 2D and 3D fracture geometry modeling. The effects of the minimum in-situ-stress profile, Young's modulus profile, and fluid-loss contrast on the fracture geometry evolution are studied. Actual field example data from a Frontier well are used for the sensitivity analyses.

Sequence Stratigraphy, Frontier Formation, South-Central Wyoming: Eustatic and Tectonic Influences

Abstract Across much of Wyoming, the mid-Cretaceous Frontier Formation is transected by an erosional unconformity of approximately 90 Ma, which forms the major sequence boundary between the Greenhorn Cycle and the Niobrara Cycle of the Western Interior Basin. In south-central Wyoming, the unconformity marks a transition from sandstone-poor deposition in the underlying Belle Fourche strata to sandstone-rich deposition in the overlying Wall Creek Member. A third Frontier unit, the member of Emigrant Gap, is discontinuously-pocketed between the Belle Fourche strata and the Wall Creek Member. Its base is also a sequence boundary, but the disconformity is contained within the rocks of the Greenhorn Cycle. The Belle Fourche, Emigrant Gap, and Wall Creek Members of the Frontier Formation in south-central Wyoming comprise an overall coarsening-upward succession which crosses the 90 Ma sequence boundary and continues well into the transgressive phase of the Niobrara Cycle, suggesting local tectonic control on Frontier deposition. Significant surfaces such as sequence boundaries or marine flooding surfaces display different characteristics in different geographic and stratigraphic locations within the Frontier. Recognition of these surfaces is critical in constructing a chronostratigraphic framework for applying sequence stratigraphy to the study of Frontier facies architecture.

Interaction of Burial History and Diagenesis of the Upper Cretaceous Frontier Formation, Moxa Arch, Green River Basin, Wyoming

Abstract Low-permeability sandstones of the Frontier Formation produce gas from reservoirs along the south-plunging Moxa Arch in the Green River Basin, southwestern Wyoming. Petrographic examination of 247 Frontier thin sections indicates that the main causes of low porosity and permeability in these sublitharenites and litharenites are compaction and cementation by quartz, calcite, and clay minerals. Major differences in burial history between the northern and southern ends of the arch have resulted in an average of 5% quartz cement in Frontier sandstones at the north end, compared with 13% at the south end. Burial histories of four wells along the north-south trend of the Moxa Arch and one well off the arch in the deep Green River Basin were reconstructed using stratigraphic data from well logs. Uplift and erosion events incorporated into the burial-history curves occurred during the Late Cretaceous, at the end of the Cretaceous, and from the Oligocene to the present. Modern geothermal gradients of 1.7 to 2.0°F/100ft (3.1 to 3.7°C/100 m) were used to model thermal maturity. Second Frontier sandstone on the La Barge Platform at the northern end of the arch (T28N, R113W) has a calculated Time-Temperature Index (TTI) value of 30, compared with a TTI of 334 in Henry field at the southern end of the arch (T13N, R113W). Second Frontier sandstone in the deep basin well (T22N, R106W) has a TTI value of 3079. In the five wells for which TTI was calculated, an excellent correlation (r = 0.95) exists between thermal maturity of the sandstone (log TTI) and average volume of quartz cement. Frontier sandstones at the southern end of the Moxa Arch and in the basin were buried to greater depths and exposed to higher temperatures than those at the northern end, so they experienced more stylolitization and intergranular pressure solution of chert, thereby liberating more silica for quartz cement. However, TTI is not a good predictor of reservoir quality because porosity and permeability in Frontier sandstones are controlled by many other variables in addition to quartz cement volume.

Characteristics of Parasequences of Transgressive System Tracts Deposited in Foreland Basins--Examples from the Cretaceous Frontier and Dakota Formations, Utah and Wyoming

Characteristics of Parasequences of Transgressive System Tracts Deposited in Foreland Basins--Examples from the Cretaceous Frontier and Dakota Formations, Utah and Wyoming

Late-Stage Diagenesis and Development of Secondary Porosity in Frontier Formation Low-Permeability Sandstones, Green River Basin, Wyoming, USA

Late-Stage Diagenesis and Development of Secondary Porosity in Frontier Formation Low-Permeability Sandstones, Green River Basin, Wyoming, USA

Natural Fracture Patterns in Sandstones of the Frontier Formation, Southwestern Wyoming

Natural Fracture Patterns in Sandstones of the Frontier Formation, Southwestern Wyoming

Frontier Formation Stratigraphy and Depositional Systems Architecture, Green River Basin, Wyoming: A Record of Sequence Development in a Proximal Foreland Basin

Frontier Formation Stratigraphy and Depositional Systems Architecture, Green River Basin, Wyoming: A Record of Sequence Development in a Proximal Foreland Basin

Hydraulic Fracturing Research in East Texas: Third GRI Staged Field Experiment

Summary This paper presents results from research conducted on the third Gas Research Inst. (GRI) staged field experiment (SFE) well. Research well SFE No. 3 was drilled as part of a field-based research program conducted in east Texas during the past 7 years. Most of the work before SFE No. 3 involved the Travis Peak formation; however, the Cotton Valley sandstone was the primary research target for this well. SFE No. 3 is the last in a series of research wells planned for east Texas. A fourth SFE planned for east Texas. A fourth SFE is being conducted in the Frontier formation of southwestern Wyoming. Data on SFE wells are collected from whole cores, open hole geophysical logs, in-situ stress measurements, production and pressure-transient production and pressure-transient tests, fracture stimulation treatments, fracture-diagnostic measurements, and postfracture performance tests. These data then are analyzed by research scientists, geologists, and engineers to describe the reservoir and hydraulic fracture fully. Introduction GRI has sponsored a field-based research program in east Texas during the past 7 program in east Texas during the past 7 years. A major effort of this program has been the SFE project, in which wells were drilled specifically to conduct research in the analysis and stimulation of tight gas sands and to validate technologies under development in other GRI research projects. The first two SFE wells have been completed and the results published in various reports and technical papers. The fourth SFE project, in the Frontier formation of project, in the Frontier formation of southwestern Wyoming, was completed in late 1991. This paper presents the results from the third SFE well. Data on SFE wells are collected from whole cores, openhole geophysical logs, insitu stress tests, production and pressure transient tests, fracture stimulation pressure transient tests, fracture stimulation treatments, fracture-diagnostic measurements, and postfracture performance tests. The main purpose of collecting such a comprehensive set of data is to describe the reservoir and hydraulic fracture fully. Our goal is to obtain the most accurate analysis possible to provide a better understanding of the possible to provide a better understanding of the hydraulic fracturing process. We hope that this work will lead to better treatment designs and additional gas production from tight gas sands, which we believe can be achieved through the practical application of new technologies and more rigorous analysis techniques with numerical models. Unless these models and tools can be applied on a more routine basis by the practicing engineer or geologist, however, technology transfer will not be accomplished. The development of practical and useful tools and methods that will benefit the natural gas industry is of primary importance to this research project. SFE No. 3 was drilled and completed in late 1958 and 1989. The lower Cotton Valley (Taylor) sand was the primary interval of completion and stimulation in this well. In this paper, we summarize the work performed and data collected on SFE No. 3 and performed and data collected on SFE No. 3 and present results from the data analyses. present results from the data analyses.

Strength Anisotropy in Low-Permeability Sandstone Gas Reservoir Rocks Application of the Axial Point-Load Test

ABSTRACT Axial point-load tests involve breaking specimen disks of rock with small, diametrically opposed anvils that approximate point loads. Direction of sample fracture can reflect strength anisotropy, which in otherwise homogeneous samples may correspond to the strike of natural microfractures or microfractures that exist owing to processes that reflect in situ stress directions, such as differential core expansion. In low-permeability sandstone reservoir rocks, point-load tests are potentially useful supplements to core-based studies of macrofractures and measurements of stress directions. Point-load tests on low-permeability sandstone core show marked strength anisotropy in soft Frontier Formation sandstone (Green River Basin, Wyoming) and moderate to weak anisotropy in hard Travis Peak Formation sandstone (East Texas Basin). Comparing results of 328 point-load tests with other stress-direction indicators (acoustic velocity anisotropy, anelastic strain recovery, wellbore breakouts, and hydraulically induced fractures), agreement was found between induced fracture strike and inferred maximum horizontal stress direction. The strike of induced fractures is also aligned with natural fracture directions in these rocks, however, and petrographic analysis is necessary in order to use point-load tests to infer stress directions.

Storm Deposition in Marine Sand Sheets: Wall Creek Member, Frontier Formation, Powder River Basin, Wyoming

ABSTRACT The Turonian (Cretaceous) Wall Creek Member, Frontier Formation and equivalent Turner Sandy Member, Carlile Shale, Powder River Basin, Wyoming were deposited on the western margin of the North American Seaway. The Seaway occupied the foreland of the Sevier Orogenic belt. The Wall Creek-Turner interval is up to 67 m thick and consists of shale, sandstone, and minor conglomerate and bentonite. Deposition occurred during rising sea level following an approximately 90 Ma lowstand. Sandstone and mudstone of the Wall Creek were deposited in thin shelf sand sheets 6-15 m thick up to approximately 120 km from equivalent shorelines. Shelf sand sheets dip gently seaward ( Core and outcrop show shelf sandstone of the Wall Creek in the Powder River Basin to consist of burrowed to bioturbated, medium-scale cross beds, near-horizontal laminated beds, and ripple-laminated beds. Reactivation surfaces and mud drapes are common. The lack of consistent periodicity across cross sets in foreset angle and thickness and unperiodic spacing of reactivation surfaces, mud drapes, and burrowed intervals suggest that tides were not an important transport process over most of the depositional area. The dominance of storm currents over tides is also indicated by variable bed thickness, structure type, grain size, and degree of burrowing vertically. Much of the mud separating beds and draping foresets likely represents sedimentation from river floods following storm events. /P>

Variations in Diagenesis and Reservoir Quality in the Frontier Formation along the Moxa Arch, Green River Basin, Wyoming: ABSTRACT

Variations in Diagenesis and Reservoir Quality in the Frontier Formation along the Moxa Arch, Green River Basin, Wyoming: ABSTRACT

Sequence Stratigraphy and Controls on Sandstone Distribution, Frontier Formation, South-Central Wyoming: ABSTRACT

Sequence Stratigraphy and Controls on Sandstone Distribution, Frontier Formation, South-Central Wyoming: ABSTRACT

Facies-Related Permeability Trends in the Frontier Formation along the Moxa Arch, Green River Basin, Wyoming: ABSTRACT

Facies-Related Permeability Trends in the Frontier Formation along the Moxa Arch, Green River Basin, Wyoming: ABSTRACT

Distribution and Significance of Mesozoic Vertebrate Trace Fossils in Dinosaur National Monument

Dinosaur National Monument (DINO) encompasses an area that has rocks with a high potential for preservation of vertebrate trace fossils, especially dinosaur tracks. The purpose of this research is to document the presence, type, and distribution of vertebrate trace fossils in Mesozoic rocks exposed in DINO. These rocks include the Moenkopi Formation, Chinle/Popo Agie Formation, Glen Canyon Sandstone, Carmel Formation, Entrada Sandstone, Morrison Formation, Cedar Mountain Formation, Dakota Formation, and Frontier Formation. This study will increase our knowledge of the stratigraphic and geographic distribution of vertebrate tracks as well as provide taxonomic, behavioral, and paleoenvironmental data. During the 1990 field season, reconnaissance of the western part of DINO revealed the presence of vertebrate trace fossils in the Chinle/Popo Agie Formation. In addition, our examination of the Moenkopi Formation suggests that vertebrate tracks are probably present in this unit. Locality information was also obtained for probable track-sites in the Carmel Formation, Entrada Sandstone, and Morrison Formation.

Parasequence Architecture in the Wall Creek Member of the Frontier Formation (Upper Cretaceous), Powder River Basin, Wyoming: ABSTRACT

Parasequence Architecture in the Wall Creek Member of the Frontier Formation (Upper Cretaceous), Powder River Basin, Wyoming: ABSTRACT

Late cretaceous and tertiary history and the dynamic crushing of cobbles, black butte area, southwestern Montana

Black Butte is an early Miocene basaltic volcanic neck that forms a prominent landmark as the highest peak of the Gravelly Range, southwestern Montana. The intrusion cuts mid-Cenozoic and older sedimentary rocks near the eastern margin of the Overthrust Belt. After erosional removal of the Late Cretaceous Frontier Formation, quartzite-rich detritus from ultimate sources probably far to the west was deposited in the area and now forms a diamicton that rests on striated bedrock. This unit, previously interpreted as a till and as a mudflow deposit, probably represents Upper Cretaceous or lower Tertiary, syntectonic alluvial-fan sediments. These were deposited after the Gravelly Arch had begun to rise and were deformed during overthrusting from the west or possibly during mass movement as the basal part of a landslide. Scattered cobbles of hard quartzite in the diamicton are crushed. If this crushing occurred within aggregates of coarse clasts that were momentarity in point contact with one another, it does not require either overthrusting or mass movement of extremely thick depositional overburden. But if a major thrust sheet did move over the diamicton, the leading edge of the Overthrust Belt must extend considerably further east of where it is currently recognized in this area. Volcanic and volcaniclastic rocks were deposited in the area throughout much or all of Oligocene time. These include tuffaceous mudstone as much as 265 m thick that contains vertebrate fossils of Chadronian through Whitneyan age. The K Ar age of biotite in an airfall tuff within this section at nearby Lion Mountain is 31.4 Ma, and the K Ar age of an alkaline basaltic flow at the top of the Lion Mountain section is 30.8 Ma. These tuffaceous rocks and basalt on Lion Mountain correlate with volcaniclastics in Wyoming and as far east as Nebraska and the Dakotas. Eruptions at Black Butte, dated previously at 22.9 Ma, begun with phreatomagmatic explosions that deposited tuff across an irregular topographic surface cut in the section of tuffaceous mudstone into which the Black Butte plug was emplaced. The alkali basalt magma differentiated to yield the relatively rare rock type tephritic phonolite during fractional crystallization and segregation in situ of potassic late liquids. Lava flows from Black Butte and the nearby Lion Mountain volcanic center may have covered much of this part of the Gravelly Range but have been mostly removed owing to erodability of the thick blanket of mudstone on which they rested. Removal of mudstone that contained the Black Butte intrusion involved massive slumping. Mass movement of the diamicton beneath the mudstone is occurring today as an earthflow down the west-dipping structural and topographic slope of the range.