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47-530: The Arkoma Basin is a peripheral foreland basin that extends from central west Arkansas to south eastern Oklahoma. The basin lies in between the Ozark Uplift and Oklahoma Platform to the north and Ouachita Mountains to the south and with an area of approximately 33,800 mi. Along the southern edge of the basin, the Choctaw Fault is the boundary that separates the mountains from the basin itself. This basin

94-407: A subaerial wedge is flanked with terrestrial or shallow marine foreland basins". The temperature underneath the orogen is much higher and weakens the lithosphere. Thus, the thrust belt is mobile and the foreland basin system becomes deformed over time. Syntectonic unconformities demonstrate simultaneous subsidence and tectonic activity. Foreland basins are filled with sediments which erode from

141-667: A direct result of the Ouachita uplift. Coal was the first hydrocarbon discovered in 1879. It was the primary natural resource extracted from the basin until need for natural gas became more widespread. The coal seams sit on top of the Hartshorne sandstone of the Desmoinesian aged deposits. The surface exploration of coal seams in the Arkoma Basin provided maps which showed closed anticlines and encouraged prospectors to drill for oil and gas. Gas

188-462: A key method for identifying the maximum temperature history of sediments in sedimentary basins . The reflectance of vitrinite was first studied by coal explorationists attempting to diagnose the thermal maturity, or rank , of coal beds. More recently, its utility as a tool for the study of sedimentary organic matter metamorphism from kerogens to hydrocarbons has been increasingly exploited. The key attraction of vitrinite reflectance in this context

235-607: A regime's tectonic origin and development as well as the lithospheric mechanics. Migrating fluids originate from the sediments of the foreland basin and migrate in response to deformation. As a result, brine can migrate over great distances. Evidence of long-range migration includes: 1) correlation of petroleum to distant source rocks , 2) ore bodies deposited from metal-bearing brines, 3) anomalous thermal histories for shallow sediments, 4) regional potassium metasomatism and 5) epigenetic dolomite cements in ore bodies and deep aquifers. Fluids carrying heat, minerals, and petroleum, have

282-463: A result, the basin strata displays high thermal maturity. Hydrocarbons in the center of the basin are classified as Type III kerogen ; characteristic of dry gas. The north/northwest corner of the basin is observed to have Type II kerogen that produces oil and wet gas. Four major erosion events along with decreased sedimentation occurred after the Mississippian period delayed gas formation. The oil that

329-454: A vast impact on the tectonic regime within the foreland basin. Before deformation, sediment layers are porous and full of fluids, such as water and hydrated minerals. Once these sediments are buried and compacted, the pores become smaller and some of the fluids, about ⁠ 1 / 3 ⁠ , leave the pores. This fluid has to go somewhere. Within the foreland basin, these fluids potentially can heat and mineralize materials, as well as mix with

376-414: Is found closer to the orogen and oil is found further away. Vitrinite Vitrinite is one of the primary components of coals and most sedimentary kerogens . Vitrinite is a type of maceral , where "macerals" are organic components of coal analogous to the "minerals" of rocks. Vitrinite has a shiny appearance resembling glass (vitreous). It is derived from the cell-wall material or woody tissue of

423-458: Is its sensitivity to temperature ranges that largely correspond to those of hydrocarbon generation (i.e. 60 to 120 °C). This means that, with a suitable calibration, vitrinite reflectance can be used as an indicator of maturity in hydrocarbon source rocks. Generally, the onset of oil generation is correlated with a reflectance of 0.5–0.6% and the termination of oil generation with reflectance of 0.85–1.1%. The onset of gas generation ('gas window')

470-490: Is located in the center of the basin where deep marine facies were not consumed by subduction. The Red Oak field is the largest gas field within the Arkoma basin and the fourth largest in the state of Oklahoma. The first well was drilled in 1912 to a total depth of 1,500 targeting the Hartshorne formation. Prior to 1959, shallow wells ranging from 1,000 ft to 1,500 ft were drilled. In May 1959, Midwest Oil Corporation spudded

517-456: Is more geologically accurate within a specific region. Seismicity determines where active zones of seismic activity occur as well as measure the total fault displacements and the timing of the onset of deformation. Foreland basins form because as the mountain belt grows, it exerts a significant mass on the Earth's crust, which causes it to bend, or flex, downwards. This occurs so that the weight of

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564-472: Is most rapid near the moving thrust sheet. Sediment transport within the foredeep is generally parallel to the strike of the thrust fault and basin axis. The motion of the adjacent plates of the foreland basin can be determined by studying the active deformation zone with which it is connected. Today GPS measurements provide the rate at which one plate is moving relative to another. It is also important to consider that present day kinematics are unlikely to be

611-430: Is one of seven that lie along the front of the Ouachita and Appalachian mountain systems. This basin is Oklahoma's fourth largest in terms of natural gas production. Oil has been extracted locally, but not on a commercial scale. Coal was the first natural resource used commercially within the basin. Surface mapping of coal seams in the early part of the 20th century lead to the discovery of sub-surface features that indicated

658-400: Is therefore common in sedimentary rocks that are rich in organic matter, such as shales and marls with a terrigenous origin, or some terrigenous content. Conversely, carbonates , evaporites and well-sorted sandstones have very low vitrinite contents. Vitrinite is absent in pre- Silurian rocks because land plants had not yet evolved. The study of vitrinite reflectance (or VR) is

705-421: Is typically associated with values of 1.0–1.3% and terminates around 3.0%. However these generation windows vary between source rocks with different kerogen types (vitrinite is typically abundant in 'Type III' kerogen-rich source rocks), so a conversion to 'transformation ratio' (TR) can be applied to create a kerogen-specific maturity parameter. The vitrinite reflectance value represents the highest temperature that

752-719: The 'Ouachita Facies' The Mississippian to early Atokan strata indicate a shallow marine environment. Middle Atokan consist primarily of deep-water clastic strata, and are restricted to the southern part of the basin south of its hinge line and to the tectonic belt; the Red Oak sandstone is the best-studied of these reservoirs. The youngest group (Desmoinesian and upper Atokan) consists mostly of fluvial-deltaic sediments (e.g., Hartshorne Formation), some of which show significant tidal influence (e.g., Booch sandstones). Post Atokan strata are shales sandstones and coal beds deposited during final phases of foreland basin sedimentation These strata thicken to

799-399: The Arkoma basin display high thermal maturity as evidenced by vitrinite reflectance (R o ) values. These values increase in grade moving from west to east within the basin. In cited literature, the rocks of Red Oak gas field would be considered overmature with an R o value of 3.0%. However, gas production has been prolific in this region. The Woodford/Chattanooga Shale, deposited during

846-602: The Middle Devonian to Lower Mississippian, is the primary source rock for pre to early Mississippian rocks. Pennsylvanian aged shales rocks sourced Pennsylvanian aged reservoirs with some influence from Chattanooga/Woodford/Caney-sourced hydrocarbons. Oil generation of this formation began in the center of the basin during the Morrowan time (320-300 Ma). The center of the basin experienced increased sedimentation rates during this period thus creating deep burial for organic material. As

893-580: The No. 1 Orr and drilled into what was later called the Red Oak Sandstone. The No. 1 Orr continued drilling past 11,510 ft. reaching the Sprio sandstone. Within two years, 25 development wells had been completed and ultimate gas recovery was already estimated at more than 1.1 tcf, even though all wells were shut in because there was not yet a pipeline to the field. Of those estimated reserves, 938 bcf were assigned to

940-518: The Red Oak sandstone and 182 bcf were assigned to the Spiro sandstone. Drilling in the Red Oak field allowed for the identification of the following productive sandstones within the Atoka Formation: Fanshawe, Red Oak, Panola, Brazil, and Spiro. However, the Spiro, Hartshorne and Red Oak sandstones have been the most significant. The traps present appear to be stratigraphical as reservoir strata

987-475: The active tectonic thrust wedge. This is where piggyback basins form. The foredeep is the thickest sedimentary zone and thickens toward the orogen. Sediments are deposited via distal fluvial, lacustrine, deltaic, and marine depositional systems. The forebulge and backbulge are the thinnest and most distal zones and are not always present. When present, they are defined by regional unconformities as well as aeolian and shallow-marine deposits. Sedimentation

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1034-404: The adjacent mountain belt. In the early stages, the foreland basin is said to be underfilled . During this stage, deep water and commonly marine sediments, known as flysch , are deposited. Eventually, the basin becomes completely filled. At this point, the basin enters the overfilled stage and deposition of terrestrial clastic sediments occurs. These are known as molasse . Sediment fill within

1081-475: The basin towards the southern extent on the north face of the Ouachita Mountains. Pre-Cambrian granite serves as the basement rock for the Arkoma strata. The ocean basin that was present during the lower Paleozoic is indicated by deep marine shales with subordinate volumes of limestone and quartzose sandstones and bedded chert lie on top of the basement rock. These sequences are referred to collectively as

1128-400: The basin. This is present in the southern part of the basin as a result of compressional tectonics and north directed thrusting. Within the Arkoma Basin, broad synclines separated by narrow anticlines dominate the basin at surface. Listric thrust faults are known to underlie much of the folded section and ramp to the surface along the crests of many anticlines. These compressional features are

1175-461: The basin. The Arkoma basin contains block faulting which occurred as a result of tensional forces as the basin subsided [during Pennsylvanian] and the Ozark uplift. These faults, most of which display southward dips, were active during deposition of lower through middle Atokan strata as indicated by significant thickening of those strata across the faults. This feature is more common in the northern part of

1222-421: The foredeep acts as an additional load on the continental lithosphere. Although the degree to which the lithosphere relaxes over time is still controversial, most workers accept an elastic or visco-elastic rheology to describe the lithospheric deformation of the foreland basin. Allen & Allen (2005) describe a moving load system, one in which the deflection moves as a wave through the foreland plate before

1269-532: The late Devonian to early Carboniferous. Subduction and subsequent formation of an accretionary prism in the early Pennsylvanian caused normal faulting throughout the basin. By late Atokan time, foreland-style thrusting became predominant as the subduction complex pushed northward against strata. The resultant uplift along the frontal thrust belt of the Ouachitas completed the formation of the foreland basin. Because of this, deformational features become more prominent in

1316-679: The lithosphere beneath the mountain range becomes ductile almost entirely, except a thin (about 6 km in the center) brittle layer near the surface and perhaps a thin brittle layer in the uppermost mantle." This lithospheric weakening underneath the orogenic belt may in part cause the regional lithospheric flexure behavior. Foreland basins are considered to be hypothermal basins (cooler than normal), with low geothermal gradient and heat flow . Heat flow values average between 1 and 2 HFU (40–90 mWm . Rapid subsidence may be responsible for these low values. Over time sedimentary layers become buried and lose porosity. This can be due to sediment compaction or

1363-424: The load system. The deflection shape is commonly described as an asymmetrical low close to the load along the foreland and a broader uplifted deflection along the forebulge. The transport rate or flux of erosion, as well as sedimentation, is a function of topographic relief. For the loading model, the lithosphere is initially stiff, with the basin broad and shallow. Relaxation of the lithosphere allows subsidence near

1410-457: The local hydrostatic head. Orogen topography is the major driving force of fluid migration. The heat from the lower crust moves via conduction and groundwater advection . Local hydrothermal areas occur when deep fluid flow moves very quickly. This can also explain very high temperatures at shallow depths. Other minor constraints include tectonic compression, thrusting, and sediment compaction. These are considered minor because they are limited by

1457-436: The mountain belt can be compensated by isostasy at the upflex of the forebulge. The plate tectonic evolution of a peripheral foreland basin involves three general stages. First, the passive margin stage with orogenic loading of previously stretched continental margin during the early stages of convergence. Second, the "early convergence stage defined by deep water conditions", and lastly a "later convergent stage during which

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1504-511: The physical or chemical changes, such as pressure or cementation . Thermal maturation of sediments is a factor of temperature and time and occurs at shallower depths due to past heat redistribution of migrating brines. Vitrinite reflectance, which typically demonstrates an exponential evolution of organic matter as a function of time, is the best organic indicator for thermal maturation. Studies have shown that present day thermal measurements of heat flow and geothermal gradients closely correspond to

1551-468: The plants from which coal was formed. Chemically, it is composed of polymers, cellulose and lignin. The vitrinite group, which consists of various individual vitrinite macerals , is the most common component of coals. It is also abundant in kerogens that are derived from the same biogenic precursors as coals, namely land plants and humic peats . Vitrinite forms diagenetically by the thermal alteration of lignin and cellulose in plant cell walls. It

1598-435: The presence of natural gas. Mansfield, Arkansas was the site of the first natural gas discovery in 1902. The region where the Arkoma basin lies began to take shape with rifting in the early Cambrian. This rifting event resulted in the formation of a deep ocean basin that persisted to the late Devonian. While experts cannot constrain the exact time when the ocean basin began to close, they can infer basin closure beginning around

1645-424: The rheological structure of the lithosphere underneath the foreland and the orogen are very different. The foreland basin typically shows a thermal and rheological structure similar to a rifted continental margin with three brittle layers above three ductile layers. The temperature underneath the orogen is much higher and thus greatly weakens the lithosphere. According to Zhou et al. (2003), "under compressional stress

1692-430: The same as when deformation began. Thus, it is crucial to consider non-GPS models to determine the long-term evolution of continental collisions and in how it helped develop the adjacent foreland basins. Comparing both modern GPS (Sella et al. 2002) and non-GPS models allows deformation rates to be calculated. Comparing these numbers to the geologic regime helps constrain the number of probable models as well as which model

1739-552: The section. In older strata, reservoirs are either quartzose sandstones (Spiro, Cromwell, and Simpson) or limestones/dolostones (Wapanucka, Mississippian, Hunton, and Arbuckle). A 2010 USGS study assessed the reservoir potential within the Woodford/Chattanooga Shale. The study cites 26 trillion ft of liquid natural gas present within the Devonian-Mississippian aged rocks. The first Coalbed Methane (CBM) well

1786-401: The slow rates of tectonic deformation, lithology and depositional rates, on the order of 0–10 cm yr , but more likely closer to 1 or less than 1 cm yr . Overpressured zones might allow for faster migration, when 1 kilometer or more of shaley sediments accumulate per 1 million years. Bethke & Marshak (1990) state that "groundwater that recharges at high elevation migrates through

1833-583: The south but do not display abrupt thickening across normal faults indicating that synde positional faulting had ceased. Four major erosion unconformities have been observed in the stratigraphic record. The formations present in Oklahoma can vary greatly from what is present in Arkansas. The lower Atokan sandstone and the Woodford/Fayetteville Shale can be observed in the eastern and western portions of

1880-441: The subsurface in response to its high potential energy toward areas where the water table is lower." Bethke & Marshak (1990) explain that petroleum migrates not only in response to the hydrodynamic forces that drive groundwater flow, but to the buoyancy and capillary effects of the petroleum moving through microscopic pores. Migration patterns flow away from the orogenic belt and into the cratonic interior. Frequently, natural gas

1927-444: The thrust, narrowing of basin, forebulge toward thrust. During times of thrusting, the lithosphere is stiff and the forebulge broadens. The timing of the thrust deformation is opposite that of the relaxing of the lithosphere. The bending of the lithosphere under the orogenic load controls the drainage pattern of the foreland basin. The flexural tilting of the basin and the sediment supply from the orogen. Strength envelopes indicate that

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1974-512: The town of Red Oak in Latimer County, Oklahoma. The south-dipping San Bois fault, located along the northern edge, is the second regional structure associated with the field. Most of the displacement associated with this normal fault occurred during the deposition of the Atoka formation between the Spiro and Fanshawe sandstones. This is indicated by growth of that section along the fault. This gas field

2021-526: The vitrinite maceral (and source rock) has experienced, and is routinely used in 1D burial modelling to identify geological unconformities in sedimentary sections. Typically vitrinite reflectance data is presented in units of %Ro, the measured percentage of reflected light from a sample which is immersed in oil (%Ro = % reflectance in oil). The lack of vitrinite macerals in marine shales with little terrestrial input often requires alternative maturity parameters instead of vitrinite reflectance such as heating

2068-448: Was drilled in 1998 utilizing horizontal drilling. This introduced a wave of renewed interest in gas extraction within the basin. The pivot to coalbed methane wells along with horizontal wells only lasted a short period; reaching its peak in 2005. After which, pursuit of these technologies all but disappeared. The Red Oak gas field lies on the axis of the Brazil anticline north and northeast of

2115-593: Was first discovered in March 1902 in Sebastian County, Arkansas. The first gas commercial well drilled in Oklahoma was completed in 1910. In both Arkansas and Oklahoma, natural resources are produced from the Devonian to Carboniferous aged rocks. The Atoka sandstones can be seen continuously in both the Oklahoma and Arkansas portions of the basin. It is believed that gas formation occurred prior to thrust faulting. The strata of

2162-426: Was present in the basin cracked to gas 10-30Ma. The erosion events across the basin's history has a more substantial impact the north/northwestern region of the basin causing hydrocarbons to stay on the low end of the gas window. Reservoir rocks of the basin include a variety of sandstones and carbonates. All reservoirs above the Spiro sandstone are lithic to sublithic arenites; no carbonates are present in that part of

2209-460: Was trapped by block faulting then rapidly overlain by younger strata. Foreland basin Foreland basins can be divided into two categories: DeCelles & Giles (1996) provide a thorough definition of the foreland basin system. Foreland basin systems comprise three characteristic properties: The wedge-top sits on top of the moving thrust sheets and contains all the sediments charging from

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