| Eolian sands develop in arid settings and commonly form extensive, blanket-like deposits (Figure 3b). Wind transport removes fines and produces rounded and extremely well sorted grains often leading to favorable reservoir quality. | | Eolian sands develop in arid settings and commonly form extensive, blanket-like deposits (Figure 3b). Wind transport removes fines and produces rounded and extremely well sorted grains often leading to favorable reservoir quality. |
− | This combination of widespread occurrence and good reservoir properties makes eolian sandstones attractive exploration targets and many hydrocarbon accumulations have been discovered in such deposits<ref name=pt06r2>Ahlbrandt, T. S., Fryberger, S. G., 1982, [http://archives.datapages.com/data/specpubs/sandsto2/data/a058/a058/0001/0000/0011.htm Introduction to eolian deposits], in Scholle, P. A., Spearing, D. eds., Sandstone Depositional Environments: [http://store.aapg.org/detail.aspx?id=627 AAPG Memoir 31], p. 11–47.</ref>). | + | This combination of widespread occurrence and good reservoir properties makes eolian sandstones attractive exploration targets and many hydrocarbon accumulations have been discovered in such deposits.<ref name=pt06r2>Ahlbrandt, T. S., Fryberger, S. G., 1982, [http://archives.datapages.com/data/specpubs/sandsto2/data/a058/a058/0001/0000/0011.htm Introduction to eolian deposits], in Scholle, P. A., Spearing, D. eds., Sandstone Depositional Environments: [http://store.aapg.org/detail.aspx?id=627 AAPG Memoir 31], p. 11–47.</ref> |
− | Eolian deposits include [[dune]], [[interdune]] (marginal to dune complex), and [[extradune]] (noneolian) lateral deposits.<ref name=pt06r2 />) Dune deposits comprise the major sedimentary bodies in eolian successions. All are characterized by large scale [[cross-stratification]] in which [[foreset]] dips range up to 35°. Associated deposits may include those of [[wadi]] (fluvial), [[playa]] (lacustrine), and [[sabkha]] (arid tidal flat) origin. | + | Eolian deposits include [[dune]], [[interdune]] (marginal to dune complex), and [[extradune]] (noneolian) lateral deposits.<ref name=pt06r2 /> Dune deposits comprise the major sedimentary bodies in eolian successions. All are characterized by large scale [[cross-stratification]] in which [[foreset]] dips range up to 35°. Associated deposits may include those of [[wadi]] (fluvial), [[playa]] (lacustrine), and [[sabkha]] (arid tidal flat) origin. |
| In the subsurface, eolian sandstones generally comprise thickly bedded sequences with few major interstratified shales. The sequences tend to be uniform and lack discernible coarsening- or fining-upward trends and, thus, exhibit blocky to weakly serrated [[Basic open hole tools#Gamma ray|gamma ray]], [[Basic open hole tools#Spontaneous potential|SP]], and [[Basic open hole tools#Resistivity|resistivity]] log profiles The well-bedded and high angle cross stratified nature of eolian sandstones promotes reliable results from [[Dipmeter analysis|dipmeter]] logs. Dune and interdune deposits can often be distinguished and paleowind directions inferred using correctly processed dipmeter data.<ref name=pt06r80>Lupe, R., Ahlbrandt, T. S., 1979, Sediments of the ancient eolian environment—reservoir inhomogeneity, in McKee, E., D., ed., A Study of Global Sand Seas: U., S. Geological Survey Professional Paper 1052, p. 241–252.</ref> | | In the subsurface, eolian sandstones generally comprise thickly bedded sequences with few major interstratified shales. The sequences tend to be uniform and lack discernible coarsening- or fining-upward trends and, thus, exhibit blocky to weakly serrated [[Basic open hole tools#Gamma ray|gamma ray]], [[Basic open hole tools#Spontaneous potential|SP]], and [[Basic open hole tools#Resistivity|resistivity]] log profiles The well-bedded and high angle cross stratified nature of eolian sandstones promotes reliable results from [[Dipmeter analysis|dipmeter]] logs. Dune and interdune deposits can often be distinguished and paleowind directions inferred using correctly processed dipmeter data.<ref name=pt06r80>Lupe, R., Ahlbrandt, T. S., 1979, Sediments of the ancient eolian environment—reservoir inhomogeneity, in McKee, E., D., ed., A Study of Global Sand Seas: U., S. Geological Survey Professional Paper 1052, p. 241–252.</ref> |