Tensleep Sandstone Research Articles

Improved reservoir characterisation using fuzzy logic platform: an integrated petrophysical, seismic structural and poststack inversion study

There is a tendency for applying different integrated geophysical approaches for better hydrocarbon reservoir characterisation and interpretation. In this study, petrophysical properties, seismic structural and poststack seismic inversion results are integrated using the fuzzy logic AND operator to characterise the Tensleep Sandstone Formation (TSF) at Powder River Basin (PRB), Wyoming, USA. TSF is deposited in a coastal plain setting during the Pennsylvanian era, and contains cross-bedded sandstone of Aeolian origin as a major lithology with alternative sabkha dolomite/carbonates. Wireline logging datasets from 17 wells are used for the detailed petrophysical evaluation. Three units of the TSF (A-sandstone, B-dolomite and B-sandstone) are targeted and their major rock properties estimated (i.e. shale/clay volume, Vsh; porosity, φEff; permeability, K; fluid saturations, Sw and SH; and bulk volume water, BVW). The B-sandstone zone, with its petrophysical properties of 5–20% effective porosity, 0.10–250 mD permeability and hydrocarbon potential up to 72%, is considered the best reservoir zone among the three studied units. Distributions of the most important petrophysical parameters of the B-sandstone reservoir (Vsh, φEff, K, Sw) are generated as GIS thematic layers.The two-dimensional (2D) and three-dimensional (3D) seismic structural interpretations revealed that the hydrocarbons are entrapped in an anticlinal structure bounded with fault closures at the west of the study area. Poststack acoustic impedance (PSAI) inversion is performed on 3D seismic data to extract the inverted acoustic impedance (AI) cube. Two attribute slices (inverted AI and seismic amplitude) were extracted at the top of the B-sandstone unit as GIS thematic layers. The reservoir properties and inverted seismic attributes were then integrated using fuzzy AND operator. Finally, a fuzzy reservoir quality map was produced, and a prospective reservoir area with best reservoir characteristics is proposed for future exploration. The current study showed that integration of petrophysical, seismic structural and poststack inversion under a fuzzy logic platform can be used as an effective tool for interpreting multiple reservoir zones.

Petrophysical Evaluation of the Tensleep Sandstone Formation Using Well Logs and Limited Core Data at Teapot Dome, Powder River Basin, Wyoming, USA

This study presents a petrophysical analysis carried out to evaluate the rock properties of the Tensleep Sandstone Formation (TSF) at Teapot Dome, Powder River Basin, Wyoming. The TSF is dominated by porous and permeable eolian cross-bedded sandstones of dune and interdune origin, but also contains marine carbonate/dolomite beds. A-sandstone, B-dolomite, and B-sandstone units of TSF were identified by the stratigraphic well log correlations and further evaluated for hydrocarbon potentiality. Shale volume, lithofacies, porosity, and fluid saturation were identified from the well logs. Permeability was empirically driven from available core data from one well. The computed effective porosity range in TSF subunits is 4–8, 5–14, and 5–20% for A-sandstone, B-dolomite, and B-sandstone, respectively. Permeability was deduced to be 0.001–3.9, 0.01–14, and 0.1–234 mD, respectively. B-sandstone was identified as the most hydrocarbon-bearing potential zone in the TSF with its hydrocarbon saturation ranging up to 72%.

Developing a model discrete fracture network, drilling, and enhanced oil recovery strategy in an unconventional naturally fractured reservoir using integrated field, image log, and three-dimensional seismic data

In this study, we develop a model discrete fracture network (DFN) for the unconventional, naturally fractured Tensleep Sandstone oil reservoir at Teapot Dome, Wyoming. Reservoir characterization is based on three-dimensional (3D) seismic data, fracture image logs from Teapot Dome, and field observations of the Tensleep exposure in the Alcova anticline and Fremont Canyon areas. Image logs reveal that the dominant reservoir fracture set trends parallel to the present-day maximum horizontal compressive stress () inferred from drilling induced fractures. Analog field studies of the Alcova anticline and Fremont Canyon suggest fracture heights and lengths are power-law distributed, while the fracture spacing distribution is best described as log-normal. Image-log–derived fracture apertures are also log-normally distributed. These properties are incorporated into a model DFN. We assume subseismic folds, faults, and fracture zones control fracture intensity distribution and use composite 3D seismic attributes to locate subtle changes in seismic response interpreted to result from subseismic structure. Directional curvature defines aperture-opening strain normal to the dominant reservoir fracture set. Seismic attributes are scaled and combined to control fracture intensity variations in the model. Grid-cell porosity and permeability distributions derived from the DFN suggest the presence of northeast–southwest-trending reservoir compartments. We suggest that enhanced oil recovery operations may be optimized using lateral injection and production wells oriented along interpreted compartment boundaries at high angles to . This combination of injection and production laterals could help maximize storage and hydrocarbon recovery in depleted reservoirs and in down-dip residual oil zones.

Detrital zircon provenance of Pennsylvanian to Permian sandstones from the Wyoming craton and Wood River Basin, Idaho, U.S.A.

Pennsylvanian rocks of the northern U.S. Rocky Mountains are mature quartzose sandstones. This paper uses detrital zircon geochronology on seven samples from the Wood River Formation, Tensleep Sandstone, and Weber Sandstone to determine if these sandstones have a common provenance, representing eastern Laurentian and Appalachian sand reworked within shallow-marine and eolian environments from the Wyoming craton westward to the Pioneer thrust plate of south-central Idaho. Our work suggests that this continental sand blanket was mixed with local sources on the south in the Yavapai-Mazatzal provinces of the Ancestral Rocky Mountains and in samples from the western Cordilleran thrust belt in south-central Idaho. In total, these Pennsylvanian sandstones contain a broad spectrum of detrital zircon U-Pb ages including, from old to young: A) minor Archean-age (3300–2550 Ma) populations; B) Paleoproterozoic (2000–1600 Ma), Mesoproterozoic (1470–1350 Ma), and major “Grenvillian” (1250–950 Ma) populations; and C) Cryogenian- to Ediacaran-age (665–565 Ma) and minor Paleozoic (495–410 Ma) populations. We interpret these detrital zircon ages to represent provenance mainly from the Appalachian mountain belt of eastern North America; however, central Appalachian versus northern Appalachian derivation is not clearly distinguished. The Weber Sandstone from the north flank of the Uinta Mountains in northeast Utah contains a strong 1700–1640 Ma age population derived from the Yavapai-Mazatzal provinces in the adjacent Ancestral Rocky Mountains. The shallow-marine Hailey Member of the Wood River Formation in south-central Idaho yields a population of >1800 Ma detrital zircons reworked from the uplifted Mississippian Copper Basin Formation. Both the Hailey and Wilson Creek Members of the Wood River Formation contain unique 640–490 Ma grains that may represent provenance from the Big Creek-Beaverhead plutonic belt of east-central Idaho and/or eastern Klamath terrane in the Klamath Mountains of northwest California and southwest Oregon. These new data support published models for Pennsylvanian–Permian transport of siliciclastic sediment with sources mainly from the North American craton, north of the Ancestral Rocky Mountains, into continental margin basins.

Evaluation of Aquifer Diversion After Large Polymer-Gel Water-Shutoff Treatments

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper SPE 132978, ’Quantitative Evaluation of Aquifer Diversion to Surrounding Wells After Multiple Large Polymer Gel Water Shutoff Treatments,’ by Ben Turner, SPE, Tiorco, and Jude Nwaozo, SPE, and Brad Funston, SPE, Marathon Oil Company, originally prepared for the 2010 SPE Production and Operations Conference and Exhibition, Tunis, Tunisia, 8-10 June. The paper has not been peer reviewed. From April through August of 2009, seven producing wells in the Spring Creek field in the Big Horn basin of Wyoming were treated with chromium-acetate-crosslinked polyacrylamide in an attempt to reduce water production, lower fluid levels, and achieve greater drawdown, resulting in improved oil production. The wells were chosen because of their high productivity, high water cut, suboptimal operation because of pump limitations, and in some cases, marginal economics. Introduction The Spring Creek field is on the west flank of the Big Horn basin in Park County, Wyoming. Structurally, Spring Creek forms an asymmetrical anticline. The main oil reservoirs in Spring Creek are the Tensleep sandstone (Pennsylvanian) and the Phosphoria formation (Permian). Both the Phosphoria and the Tensleep are connected to prolific aquifers that supply reservoir energy, but also supply a high rate of water. In most wells in the field, both formations are produced and commingled, but in many wells, the Tensleep is so productive that the well is limited in lifting capacity and the Phosporia has not been perforated. The well spacing in the field averages approximately 5 acres. Strategy The operator has an extensive history of shutting off water production by use of chromium-crosslinked polyacrylamide gels. By using chromium acetate as a delayed crosslinker for partially hydrolyzed polyacrylamide, a large volume (as much as 11,500 bbl in this case) can be injected and then allowed to cure for a week. When the gel cures, it reduces the permeability of the fracture and is able to withstand a high differential pressure such as that seen in the near-wellbore region of a producing well. The gel is bullheaded through tubing, with a packer set above the productive formations. Because of the large permeability difference between the fractures and the formation matrix, the gel will penetrate the fractures and significantly reduce the permeability, reducing the water production and fluid level, thus allowing the well to be pumped off and oil production to be increased. This technique has been used quite successfully in several hundred applications throughout the USA.

The Wyoming carbon underground storage project: Geologic characterization of the Moxa Arch and Rock Springs Uplift

The Wyoming carbon underground storage project: Geologic characterization of the Moxa Arch and Rock Springs Uplift

Complex fracture development related to stratigraphic architecture: Challenges for structural deformation prediction, Tensleep Sandstone at the Alcova anticline, Wyoming

Fracture prediction in subsurface reservoirs is critical for exploration through exploitation of hydrocarbons. Methods of predicting fractures commonly neglect to include the stratigraphic architecture as part of the prediction or characterization process. This omission is a critical mistake. We have documented a complex heterogeneous fracture development within the eolian Tensleep Sandstone in Wyoming, which arguably is one of the least complex reservoir facies. Fractures develop at four scales of observation: lamina-bound, facies-bound, sequence-bound, and throughgoing fractures that span the formation. We documented a detailed facies and fracture-intensity model using LIDAR-scanned outcrops located at the Alcova anticline in central Wyoming. Through this characterization, we reveal the existence of a striking variability in fracture intensity caused by original depositional architecture, overall structural deformation, and diagenetic alteration of the host rock.

Detailed compositional analysis of gas seepage at the National Carbon Storage Test Site, Teapot Dome, Wyoming, USA

A baseline determination of CO 2 and CH 4 fluxes and soil gas concentrations of CO 2 and CH 4 was made over the Teapot Dome oil field in the Naval Petroleum Reserve No. 3 (NPR-3) in Wyoming, USA. This was done in anticipation of experimentation with CO 2 sequestration in the Pennsylvanian Tensleep Sandstone underlying the field at a depth of 1680 m. The baseline data were collected during the winter, 2004 in order to minimize near-surface biological activity in the soil profile. The baseline data were used to select anomalous locations that may be the result of seeping thermogenic gas, along with background locations. Five 10-m holes were drilled, 3 of which had anomalous gas microseepage, and 2 were characterized as “background.” These were equipped for nested gas sampling at depths of 10-, 5-, 3-, 2-, and 1-m depths. Methane concentrations as high as 170,000 ppmv (17%) were found, along with high concentrations of C 2H 6, C 3H 8, n-C 4H 10, and i-C 4H 10. Much smaller concentrations of C 2H 4 and C 3H 6 were observed indicating the beginning of hydrocarbon oxidation in the anomalous holes. The anomalous 10-m holes also had high concentrations of isotopically enriched CO 2, indicating the oxidation of hydrocarbons. Concentrations of the gases decreased upward, as expected, indicating oxidation and transport into the atmosphere. The ancient source of the gases was confirmed by 14C determinations on CO 2, with radiocarbon ages approaching 38 ka within 5 m of the surface. Modeling was used to analyze the distribution of hydrocarbons in the anomalous and background 10-m holes. Diffusion alone was not sufficient to account for the hydrocarbon concentration distributions, however the data could be fit with the addition of a consumptive reaction. First-order rate constants for methanotrophic oxidation were obtained by inverse modeling. High rates of oxidation were found, particularly near the surface in the anomalous 10-m holes, demonstrating the effectiveness of the process in the attenuation of CH 4 microseepage. The results also demonstrate the importance of CH 4 measurements in the planning of a monitoring and verification program for geological CO 2 sequestration in sites with significant remaining hydrocarbons (i.e. spent oil reservoirs).

Baseline studies of surface gas exchange and soil-gas composition in preparation for CO2 sequestration research: Teapot Dome, Wyoming

A baseline determination of CO2 and CH4 fluxes and soil-gas concentrations of CO2 and CH4 was made over the Teapot Dome oil field in the Naval Petroleum Reserve 3 in Natrona County, Wyoming, United States. This was done in anticipation of the experimentation with CO2 sequestration in the Pennsylvanian Tensleep Sandstone underlying the field at a depth of 5500 ft (1680 m). The measurements were made in January 2004 to capture the system with minimum biological activity in the soils, resulting in a minimum CO2 flux and a maximum CH4 flux. The CO2 fluxes were measured in the field with an infrared spectroscopic method. The CH4 fluxes were determined from gas-chromatographic measurements on discrete samples from under the flux chambers. The CO2 and CH4 were determined at 30-, 60-, and 100-cm (11-, 23-, and 39-in.) depths in soil gas by gas chromatography. A total of 40 locations had triplicate flux measurements using 1.00-m2 (10.763-ft2) chambers, and soil gas was sampled at single points at each of the 40 locations. Carbon dioxide fluxes averaged 227.1 mg CO2 m2 day1, a standard deviation of 186.9 mg m2 day1, and a range of 281.7 to 732.9 mg m2 day1, not including one location with subsurface infrastructure contamination. Methane fluxes averaged 0.137 mg CH4 m2 day1, standard deviation of 0.326 mg m2 day1, and a range of 0.481 to 1.14 mg m2 day1, not including the same contaminated location. Soil-gas CO2 concentrations increased with depth, averaging 618, 645, and 1010 ppmv at 30, 60, and 100 cm (11, 23, and 39 in.), respectively. Soil-gas CH4 concentrations averaged 0.128, 0.114, and 0.093 ppmv at 30, 60, and 100 cm (11, 23, and 39 in.), respectively. The decrease in CH4 with depth reflects a slow rate of methanotrophic oxidation, even during winter conditions. The 13C of the soil gas CO2 was also determined in the soil-gas samples and in the atmosphere. These data demonstrated that the increased CO2 with depth was derived from the biological oxidation of soil organic matter.

Paleontological Survey of Grand Teton National Park

A comprehensive paleontological survey of Grand Teton National Park (GTNP) was completed during the 2002 and 2003 field seasons. A number of formations from within the park have yielded a variety of invertebrate, vertebrate, and plant fossils. The following formations (listed in stratigraphic sequence from oldest to youngest) were surveyed in this study: the Gros Ventre, Gallatin Limestone, Bighorn Dolomite, Darby, Madison Limestone, Amsden, Tensleep Sandstone, Phosphoria, Dinwoody, Chugwater, Gypsum Springs, Sundance, Morrison, Cloverly, Thermopolis, Mowry Shale, Frontier, Cody Shale, Bacon Ridge Sandstone, Sohare, Mesaverde, Meeteetse, Harebell, Pinyon Creek, Hominy Peak, Colter, Teewinot, and Huckleberry Ridge Tuff. Comments on the depostional environments of the various formations are based on field observations and analysis of voucher specimens. This study provides a greater understanding of the extensive paleontological resources present in the park.

An integrated 3-D reservoir characterization at Riverton Dome Field, Wyoming

Riverton Dome is a prime example of a mature Rocky Mountain oil and gas field that has benefited from new drilling based on a recent 3-D seismic survey. The field was discovered in 1949 through surface geology and seismic (Hinton, 1957; Borgerding, 1989) and was acquired by Snyder Oil Corporation (SOCO) in 1993. In 1998 SOCO acquired a 38-mi2 3-D seismic survey over Riverton Dome Field with funding from Belco Energy, Tom Brown Incorporated, and the U.S. Department of Energy to determine reservoir distribution, structural configuration, and compartmentalization. The survey was acquired with fractionated bins to image the steep dip on the flanks of the structure as a cost-effective alternative to using a smaller bin size. It was processed independently by two vendors. Results were very similar, providing confidence in the high quality of the data. Geologic maps were integrated with various seismic attributes to define reservoir models and to project reservoir trends beyond the current field. As a result of the Riverton Dome 3-D study, three successful wells were drilled in the Muddy Sandstone and additional opportunities in multiple Upper Cretaceous reservoirs and the Tensleep Sandstone were identified. Riverton Dome, a structurally controlled, mature oil and gas field is on the Wind River Indian Reservation, approximately six miles southeast of the town of Riverton in the southwestern portion of Wyoming's Wind River Basin (Figure 1). A series of thrust-faulted anticlines strikes NNW-SSE, parallel to the large Wind River Mountain thrust to the west. These features formed in the Late Cretaceous-Paleocene during the early stages of the Laramide orogeny (Keefer, 1965, 1970; Gries, 1983). Both Riverton Dome Field and Beaver Creek Field to the south are on the crest of a north-plunging asymmetrical anticline bounded on the west by a steeply dipping thrust fault that originates in basement. The …

ABSTRACT: Structural and Stratigraphic Compartments Determined from Horizontal Drilling in an Eolian Reservoir, Tensleep Sandstone, Wyoming

ABSTRACT: Structural and Stratigraphic Compartments Determined from Horizontal Drilling in an Eolian Reservoir, Tensleep Sandstone, Wyoming

ABSTRACT: Outcrop based 3-D modeling of the Tensleep Sandstone at Alkali Creek, Bighorn Basin, Wyoming

ABSTRACT: Outcrop based 3-D modeling of the Tensleep Sandstone at Alkali Creek, Bighorn Basin, Wyoming

Experimental study on water–rock interactions during CO 2 flooding in the Tensleep Formation, Wyoming, USA

The conditions for mineral alteration and formation damage during CO 2 treatment of Tensleep sandstone reservoirs in northern Wyoming, USA, were examined through core-flooding laboratory experiments carried out under simulated reservoir conditions (80°C and 166 bars). Subsurface cores from the Tensleep sandstone, which were cemented by dolomite and anhydrite, and synthetic brines were used. The brines used were (Ca, Mg, Na)SO 4–NaCl solution (9.69 g/l total dissolved solids) for Run 1 and a 0.25 mol/l NaCl solution for Run 2. The solution used in Run 1 was saturated with respect to anhydrite at run conditions, which is characteristic of Tensleep Formation waters. Three major reactions took place during flooding, including (1) dissolution of dolomite, (2) alteration of K-feldspar to form kaolinite, and (3) precipitation (in Run 1) or dissolution (in Run 2) of anhydrite. All sample solutions remained undersaturated with respect to carbonates. The permeability of all the cores (except one used in Run 2) decreased during the experiments despite the dissolution of authigenic cement. Kaolinite crystal growth occurring in pore throats likely reduced the permeability. Application of the experimental results to reservoirs in the Tensleep Formation indicates that an injection solution will obtain saturation with respect to dolomite (and anhydrite) in the immediate vicinity of the injection well. The injection of NaCl-type water, which can be obtained from other formations, causes a greater increase in porosity than the injection of Tensleep Formation waters because of the dissolution of both dolomite and anhydrite cements.

Abstract: Fracture Architecture of the Tensleep Sandstone, Bighorn Basin, Wyoming: Surface Analogs for Subsurface Reservoirs 

Abstract: Fracture Architecture of the Tensleep Sandstone, Bighorn Basin, Wyoming: Surface Analogs for Subsurface Reservoirs 

Abstract: Facies Architecture of the Tensleep Sandstone, Bighorn Basin Wyoming: Outcrop Analogs to Subsurface Reservoirs 

Abstract: Facies Architecture of the Tensleep Sandstone, Bighorn Basin Wyoming: Outcrop Analogs to Subsurface Reservoirs 

Abstract: Facies Architecture of The Tensleep Sandstone Bighorn Basin, North-Central Wyoming

Abstract: Facies Architecture of The Tensleep Sandstone Bighorn Basin, North-Central Wyoming

Redox reactions in hydrocarbon clastic reservoirs: experimental validation of this mechanism for porosity enhancement

Oil-rock-water reactions in hydrocarbon reservoirs were evaluated experimentally. Hematitic Tensleep Sandstone samples of 10–20 cm 3 were heated with 200 ml of deionized water and 100 ml of petroleum for 3–14 days at 200–360°C. The Tensleep Sandstone samples are mature quartz arenites with 5–25% carbonate matrix and cement and minor amount of anhydrite pore-fillings. Results indicate that significant potential exists for redox reactions between oxidized mineral phases and crude oil. Iron oxides (± sulfate) were reduced and hydrocarbons were oxidized to oxygenated organic compounds (such as CO 2 and organic acids). Organic acids generated during the redox reactions partitioned into the system water, dissolving framework grains and cements (primarily carbonates). Original porosity of the samples ranged from 6% to 15%, and increased by ∼ 13–20%, to 7–18%, or more after experimentation. As reactions between hydrocarbons and mineral oxidants proceed, redox reactions occur, under increasingly reducing condition as temperature increases, and result in enhanced sandstone reservoir porosity.

Facies and Fracture Architecture of the Tensleep Sandstone, Bighorn Basin, Wyoming: Preiiminary Result of an Outcrop and Subsurface Study: ABSTRACT

The Middle Pennsylvanian to Lower Permian Tensleep Sandstone has been the most prolific producer in the state of Wyoming. Now in its advanced stages of production. it is critical to accurately characterize the Tensleep facies and fracture architecture. Two outcrop locations have been selected: Alkali Creek has cross-strata dip parallel exposures at close spacings for eolian facies architecture Ziesman Dome is an NW-SE trending asymmetric anticlinal closure with the SE axis having a marked dextral dislocation, and is selected for analysis of fracture architecture. Byron Field is also an anticlinal closure with NW-SE trend which is selected for location of subsurface study. Methods of study for outcrop includes high- precision electronic surveying, photomosaics, geologic mapping, and fracture spacing and orientation measurements. The subsurface study includes conventional wireline logs, cores, and porosity and permeability data. In addition, a microresistivity log was evaluated from the Lindsay 3H horizontal well. Tensleep facies architecture is defined by a hierarchy of elements. Parasequences are made up of marine to marginal marine dolomitic sandstones and sandy dolostones (<10[sup -2] to 10[sup 2] md) in the lower 20-50%, and eolian dune, interdune and large-scale deformed sandstones in the upper part. Eolian dune sandstones, the primary reservoir (2more » to 3x10[sup 2] md), am characterized by very large-scale (up to 40 ft thick) tabular-planar cross strata with lower permeability wind ripple strata (1 to 2x10[sup 2] md, strongly anisotropic) concentrated above 1st- and 2nd-order bounding surfaces. Medium-scale trough cross stratified intrasets are common; however, their spatial dimensions and distribution pattern are uncertain at this time.« less

South Casper Creek Field: A Study in Reservoir Heterogeneity

The Tensleep Sandstone, an eolian and marine deposit, has produced low-gravity oil at South Casper Creek field (Natrona County, Wyoming) since the 1920s. Until recently, the reservoir was considered a relatively homogeneous sandstone body and was modeled as such for secondary recovery operations initiated during the late 1970s and early 1980s. Poor secondary recovery performance led to extensive reevaluation of the reservoir. Characterization studies by the field operator, Union Oil of California (UNOCAL), and through the Reservoir Characterization Project at the Colorado School of Mines produced an entirely revised picture of the Tensleep interval. Significant stratigraphic, diagenetic, and structural heterogeneities were identified, mapped, and correlated against productivity patterns under pilot steamflood programs. The results of this integrated geologic and geophysical effort are significant and have implications for secondary recovery operations elsewhere in the Tensleep and its regional correlatives.