Suitability of high-resolution seismic method to identifying petroleum reservoirs in Kansas--a geological perspective

Kansas has been a part of a stable craton since at least the beginning of the Paleozoic some 550 m. y. ago. The majority of the sedimentary rocks deposited during the last 550 m. y. are products of numerous inundations by shallow seas. Interspersed with these transgressions were periods of erosion, many coinciding with widespread uplift. The distribution of reservoir-quality rocks has been controlled by the varying structural and depositional settings in both time and space. The identification of these reservoirs begins with a knowledge of the geologic history as detailed by the vast subsurface information base, mainly wire line logs and completion records, that is available for Kansas. Seismic profiling has been and will continue to be used effectively to resolve structural traps. The trend in exploration in the midcontinent has been to strengthen the search for reservoirs associated with more subtle structures and difficult-to-find stratigraphic traps. Stratigraphic traps will become increasingly important, particularly within established production trends. The many unconformities in the midcontinent stratigraphic column afford numerous types of trapping geometry such as truncation beneath an unconformity, traps associated with buried valleys, discontinuous onlap onto erosion surfaces, and porosity pinchouts due to changes in original depositional conditions and diagenetic alteration. The most widespread petroleum accumulations in Kansas occur in structural and stratigraphic traps associated with the pre-Pennsylvanian unconformity. Production associated with the unconformity includes numerous lower Paleozoic pay zones which subcrop directly beneath the unconformity in the Sedgwick, Salina, and Anadarko basins; the Arbuckle production on the Central Kansas uplift; and numerous fields which payout from either conglomerates or weathered zones along the unconformity. Considerable production also occurs farther up-section with the Cherokee and Lansing-Kansas City groups, and down-section in the Viola Formation and Simpson Group. In order to demonstrate the potential use of the seismic method in defining subtle traps, synthetic seismograms were produced for selected strata in central Kansas. Critical attributes of reservoir rock and associated strata conducive to seismic stratigraphic processing include the thickness of a potential reservoir bed and its velocity and density contrast with adjacent strata. Thicker strata such as the Morrow and most lower Paleozoic formations may be more easily defined by seismic-stratigraphic methods. In contrast, the stratigraphy of the Pennsylvanian and Permian cyclothems may not be amenable to definition by seismic methods because these units contain heterogenous reservoirs interbedded with other thin strata of similar composition

Suitability of high-resolution seismic method to identifying petroleum reservoirs in Kansas--a geological perspective

Kansas has been a part of a stable craton since at least the beginning of the Paleozoic some 550 m. y. ago. The majority of the sedimentary rocks deposited during the last 550 m. y. are products of numerous inundations by shallow seas. Interspersed with these transgressions were periods of erosion, many coinciding with widespread uplift. The distribution of reservoir-quality rocks has been controlled by the varying structural and depositional settings in both time and space. The identification of these reservoirs begins with a knowledge of the geologic history as detailed by the vast subsurface information base, mainly wire line logs and completion records, that is available for Kansas. Seismic profiling has been and will continue to be used effectively to resolve structural traps. The trend in exploration in the midcontinent has been to strengthen the search for reservoirs associated with more subtle structures and difficult-to-find stratigraphic traps. Stratigraphic traps will become increasingly important, particularly within established production trends. The many unconformities in the midcontinent stratigraphic column afford numerous types of trapping geometry such as truncation beneath an unconformity, traps associated with buried valleys, discontinuous onlap onto erosion surfaces, and porosity pinchouts due to changes in original depositional conditions and diagenetic alteration. The most widespread petroleum accumulations in Kansas occur in structural and stratigraphic traps associated with the pre-Pennsylvanian unconformity. Production associated with the unconformity includes numerous lower Paleozoic pay zones which subcrop directly beneath the unconformity in the Sedgwick, Salina, and Anadarko basins; the Arbuckle production on the Central Kansas uplift; and numerous fields which payout from either conglomerates or weathered zones along the unconformity. Considerable production also occurs farther up-section with the Cherokee and Lansing-Kansas City groups, and down-section in the Viola Formation and Simpson Group. In order to demonstrate the potential use of the seismic method in defining subtle traps, synthetic seismograms were produced for selected strata in central Kansas. Critical attributes of reservoir rock and associated strata conducive to seismic stratigraphic processing include the thickness of a potential reservoir bed and its velocity and density contrast with adjacent strata. Thicker strata such as the Morrow and most lower Paleozoic formations may be more easily defined by seismic-stratigraphic methods. In contrast, the stratigraphy of the Pennsylvanian and Permian cyclothems may not be amenable to definition by seismic methods because these units contain heterogenous reservoirs interbedded with other thin strata of similar composition

Nonlinear-Optical Studies of a Fluorinated Poled Polyimide Guest-Host System

We report on poling of a low dielectric constant preimidized fluorinated fully aromatic guest-host polyimide nonlinear optical material including thermal stability of optical nonlinearities and waveguiding properties. We measured a second-harmonic coefficient (d33 = 4.9 +/- 0.5 pm/V at 1217 nm fundamental wavelength) which is accurately predicted by a thermodynamic model of poled polymers. The optical nonlinearity of a poled sample was thermally stable at 80-degrees-C for over 300 h. Films were observed to have negative birefringence. Optical losses for slab waveguides in lowest order TE and TM modes were greater-than-or-equal-to 7.7 dB/cm for doped waveguides at 800 nm wavelength and increased after poling

Double Twist in Helical Polymer Soft Crystals

In natural and synthetic materials having non-racemic chiral centers, chirality and structural ordering each play a distinct role in the formation of ordered states. Configurational chirality can be extended to morphological chirality when the phase, structures possess low liquid crystalline order. In the crystalline states the crystallization process suppresses the chiral helical morphology due to strong ordering interactions, In this Letter, we report the first observation of helical single lamellar crystals of synthetic non-racemic chiral polymers. Experimental evidence shows that the molecular chains twist along both the long and short axes of the helical lamellar crystals, which is the first time a double-twist molecular orientation in a helical crystal has been observed