Geothermal resources of the Texas Gulf Coast- Environmental concerns arising from the production and disposal of geothermal waters.

Disposal and temporary storage of spent geothermal fluids and surface subsidence and faulting are the major environmental problems that could arise from geopressured geothermal water production. Geopressured geothermal fluids are moderately to highly saline (8,000 to 72,000 parts per million total dissolved solids) and may contain significant amounts of boron (19 to 42 parts per million). Disposal of hot saline geothermal water in the subsurface saline aquifers will present the least hazard to the environment. It is not known, however, whether the disposal of as much as 54,000 m3 (310,000 barrels) of spent fluids per day into saline aquifers at the production site is technically or economically feasible. If saline aquifers adequate for fluid disposal cannot be found, geothermal fluids may have to be disposed of by open watercourses, canals and pipelines to coastal bays on the Gulf of Mexico. Overland flow or temporary storage of geothermal fluids may cause negative environmental impacts. As the result of production of large volumes of geothermal fluid, reservoir pressure declines may cause compaction of sediments within and adjacent to the reservoir. The amount of compaction depends on pressure decline, reservoir thickness, and reservoir compressibility. At present, these parameters can only be estimated. Reservoir compaction may be translated in part to surface subsidence. When differential compaction occurs across a subsurface fault, fault activation may occur and be manifested as differential subsidence across the surface trace of the fault or as an actual rupture of the land surface. The magnitude of environmental impact of subsidence and fault activation varies with current land use; the greatest impact would occur in urban areas, whereas relatively minor impacts would occur in rural, undeveloped agricultural areas. Geothermal resource production facilities on the Gulf Coast of Texas could be subject to a series of natural hazards: (1) hurricane- or storm-induced flooding, (2) winds from tropical storms, (3) coastal erosion, or (4) expansive soils. None of these hazards is generated by geothermal resource production, but each has potential for damaging geothermal production and disposal facilities that could, in turn, result in leakage of hot saline geothermal fluids

Salt Dissolution: Examples from Beneath the Southern High Plains

Regional salt dissolution and the subsequent collapse of overlying strata have affected substantial parts of the Texas and Oklahoma Panhandles (Gustavson and others, 1980; Johnson, 1981). There are seven salt-bearing units within the Permian System of the Texas Panhandle and eastern New Mexico. With the probable exception of the lower Clear Fork Formation, all the younger salt-bearing units are locally undergoing dissolution. Several lines of evidence support the conclusion that zones of salt dissolution underlie parts of the Southern High Plains, the Rolling Plains, and the Canadian River Breaks (Gustavson and others, 1980, 1982): (1) The major streams draining the region surrounding the Southern High Plains carry high-solute loads, indicating that dissolution is active. For example, the Prairie Dog Town Fork of the Red River carries a mean annual solute load of 1,003.4 x 103 tons of dissolved solids per year, including 425.3 x 103 tons of chloride per year (U.S. Geological Survey, 1969-1977). Brine springs, salt springs, and salt pans appear along this and other stream valleys. (2) The abrupt loss of salt sequences between relatively closely spaced oil and gas exploration wells indicates salt dissolution and not facies change. Structural collapse of overlying strata is evident in the wells where salt is missing (fig. 1). (3) Brecciated zones, fractures with slickensides, extension fractures filled with gypsum, and insoluble residues composed of mud, anhydrite, or dolomite overlie the uppermost salts in cores from the DOE-Gruy Federal No. 1 Rex H. White well in Randall County, the DOE-Gruy Federal No. 1 D. N. Grabbe well and the Stone and Webster Engineering Corp. No. 1 Zeeck and No. 1 Harmon wells in Swisher County, the Stone and Webster Engineering Corp. No. 1 Sawyer well in Donley County, the Stone and Webster Engineering Corp. No. 1 G. Friemel, No. 1 J. Friemel and No. 1 Deten wells in Deaf Smith County, and the Stone and Webster Engineering Corp. No. Mansfield well in Oldham County. (4) Numerous sinkholes and closed depressions (dolines) have formed recently in the Rolling Plains and are interpreted to be the result of dissolution and subsidence (Gustavson and others, 1982). (5) Permian outcrops both east of the Caprock Escarpment and in the Canadian River valley display folds, systems of extension fractures, breccia beds, and remnants of caverns. Structural, stratigraphic, core, and geomorphic evidence suggest that salt dissolution was active beneath the Southern High Plains during the Pliocene and probably the Pleistocene. Two case studies are presented, one describing evidence for dissolution in eastern Deaf Smith County and one describing evidence for dissolution in eastern Swisher County. Using core and stratigraphic data interpretations of the geology in the two case study areas can be extrapolated to the preferred sites in Deaf Smith and Swisher Counties. In each case, it is both reasonable and conservative to infer that dissolution and subsidence of overlying strata occurred during the Pliocene and probably during the Pleistocene.Bureau of Economic Geolog

Propagation of Bose-Einstein condensates in a magnetic waveguide

Gaseous Bose-Einstein condensates of 2-3 million atoms were loaded into a microfabricated magnetic trap using optical tweezers. Subsequently, the condensates were released into a magnetic waveguide and propagated 12 mm. Single-mode propagation was observed along homogeneous segments of the waveguide. Inhomogeneities in the guiding potential arose from geometric deformations of the microfabricated wires and caused strong transverse excitations. Such deformations may restrict the waveguide physics that can be explored with propagating condensates.Comment: 5 pages, 4 figure

First electron beam polarization measurements with a Compton polarimeter at Jefferson Laboratory

A Compton polarimeter has been installed in Hall A at Jefferson Laboratory. This letter reports on the first electron beam polarization measurements performed during the HAPPEX experiment at an electron energy of 3.3 GeV and an average current of 40 $\mu$A. The heart of this device is a Fabry-Perot cavity which increased the luminosity for Compton scattering in the interaction region so much that a 1.4% statistical accuracy could be obtained within one hour, with a 3.3% total error

Transport of Bose-Einstein Condensates with Optical Tweezers

We have transported gaseous Bose-Einstein condensates over distances up to 44 cm. This was accomplished by trapping the condensate in the focus of an infrared laser and translating the location of the laser focus with controlled acceleration. Condensates of order 1 million atoms were moved into an auxiliary chamber and loaded into a magnetic trap formed by a Z-shaped wire. This transport technique avoids the optical and mechanical access constraints of conventional condensate experiments and creates many new scientific opportunities.Comment: 5 pages, 3 figure

Stability of axial orbits in galactic potentials

We investigate the dynamics in a galactic potential with two reflection symmetries. The phase-space structure of the real system is approximated with a resonant detuned normal form constructed with the method based on the Lie transform. Attention is focused on the stability properties of the axial periodic orbits that play an important role in galactic models. Using energy and ellipticity as parameters, we find analytical expressions of bifurcations and compare them with numerical results available in the literature.Comment: 20 pages, accepted for publication on Celestial Mechanics and Dynamical Astronom

Selective nanomanipulation using optical forces

We present a detailed theoretical study of the recent proposal for selective nanomanipulation of nanometric particles above a substrate using near-field optical forces [Chaumet {\it et al.} Phys. Rev. Lett. {\bf 88}, 123601 (2002)]. Evanescent light scattering at the apex of an apertureless near-field probe is used to create an optical trap. The position of the trap is controlled on a nanometric scale via the probe and small objects can be selectively trapped and manipulated. We discuss the influence of the geometry of the particles and the probe on the efficiency of the trap. We also consider the influence of multiple scattering among the particles on the substrate and its effect on the robustness of the trap.Comment: 12 pages, 17 figure

Novel Ferromagnetic Atom Waveguide with in situ loading

Magneto-optic and magnetostatic trapping is realized near a surface using current carrying coils wrapped around magnetizable cores. A cloud of 10^7 Cesium atoms is created with currents less than 50 mA. Ramping up the current while maintaining optical dissipation leads to tightly confined atom clouds with an aspect ratio of 1:1000. We study the 3D character of the magnetic potential and characterize atom number and density as a function of the applied current. The field gradient in the transverse dimension has been varied from < 10 G/cm to > 1 kG/cm. By loading and cooling atoms in-situ, we have eliminated the problem of coupling from a MOT into a smaller phase space.Comment: 4 pages, 4 figure

From Heisenberg matrix mechanics to EBK quantization: theory and first applications

Despite the seminal connection between classical multiply-periodic motion and Heisenberg matrix mechanics and the massive amount of work done on the associated problem of semiclassical (EBK) quantization of bound states, we show that there are, nevertheless, a number of previously unexploited aspects of this relationship that bear on the quantum-classical correspondence. In particular, we emphasize a quantum variational principle that implies the classical variational principle for invariant tori. We also expose the more indirect connection between commutation relations and quantization of action variables. With the help of several standard models with one or two degrees of freedom, we then illustrate how the methods of Heisenberg matrix mechanics described in this paper may be used to obtain quantum solutions with a modest increase in effort compared to semiclassical calculations. We also describe and apply a method for obtaining leading quantum corrections to EBK results. Finally, we suggest several new or modified applications of EBK quantization.Comment: 37 pages including 3 poscript figures, submitted to Phys. Rev.

Bohr-Sommerfeld Quantization of Periodic Orbits

We show, that the canonical invariant part of $\hbar$ corrections to the Gutzwiller trace formula and the Gutzwiller-Voros spectral determinant can be computed by the Bohr-Sommerfeld quantization rules, which usually apply for integrable systems. We argue that the information content of the classical action and stability can be used more effectively than in the usual treatment. We demonstrate the improvement of precision on the example of the three disk scattering system.Comment: revte