Avery Island Research Articles

The salt-dome landscape genesis: paradoxes of rational nature management

The paper considers regional peculiarities of the use of natural resource potential of landscape geosystems formed in the course of halokinesis. Parameters of stability of salt-dome geosystems to anthropogenic influence resulting from the interaction of geodynamic processes and physical-geographical conditions are estimated. A method to evaluate the stability of landscape geosystems formed by salt-dome processes to anthropogenic transformation is offered. Accounting of volume of underground natural resources management connected, mainly, with salt rock extraction is significant. Excess of the total square of all forms of nature management under an area of the landscape geosystem formed by salt diapir, represented as the coefficient of nature management (CNM), acts as trigger risk. There are regularities of transforming the natural management structure in the regional models on the examples of basins: the Caspian-Cis-Urals, Trans-Carpathian, the Catalan, and Mexican. Within landscape geosystems having a salt-dome origin, the indicator of the coefficient of nature management can show as balanced geosystems, despite the development of subsurface resource management (Avery Island) or being in crisis geoecological situation (Iletskiy dome), so experienced anthropogenic catastrophes of different types (Jefferson Island, the Solotvinskiy dome). Principals of safe subsurface resource management and rational recreational-touristic use within salt structures of open kinds were developed.

Very Slow Creep Tests on Salt Samples

The objective of this paper is to assess the creep law of natural salt in a small deviatoric stress range. In this range, creep is suspected to be much faster than what is predicted by most constitutive laws used in the cavern and mining industries. Five 2-year, multistage creep tests were performed with creep-testing devices set in a gallery of the Altaussee mine in Austria to take advantage of the very stable temperature and humidity conditions in this salt mine. Each stage was 8-month long. Dead loads were applied, and vertical displacements were measured through gages that had a resolution of 12.5 nm. Loading steps were 0.2, 0.4, and 0.6 MPa, which are much smaller than the loads that are usually applied during creep tests (5–20 MPa). Five salt samples were used: two samples were cored from the Avery Island salt mine in Louisiana, United States; two samples were cored from the Gorleben salt mine in Germany; and one sample was cored from a deep borehole at Hauterives in Drome, France. During these tests, transient creep is relatively long (6–10 months). Measured steady-state strain rates ( $$\dot {\varepsilon }$$ = 10−13–10−12 s−1) are much faster (by 7–8 orders of magnitude) than those extrapolated from relatively high-stress tests (σ = 5–20 MPa). When compared to n = 5 within the high-stress domain for Gorleben and Avery Island salts, a power-law stress exponent within the low-stress domain appears to be close to n = 1. These results suggest that the pressure solution may be the dominant deformation mechanism in the steady-state regime reached by the tested samples and will have important consequences for the computation of caverns or mines behavior. This project was funded by the Solution-Mining Research Institute.

Micromechanical processes in consolidated granular salt

Granular salt is likely to be used as backfill material and a seal system component within geologic salt formations serving as a repository for long-term isolation of nuclear waste. Pressure from closure of the surrounding salt formation will promote consolidation of granular salt, eventually resulting in properties comparable to native salt. Understanding dependence of consolidation processes on stress state, moisture availability, temperature, and time is important for demonstrating sealing functions and long-term repository performance. This study characterizes laboratory-consolidated granular salt by means of microstructural observations. Granular salt material from mining operations was obtained from the bedded Salado Formation hosting the Waste Isolation Pilot Plant and the Avery Island salt dome. Laboratory test conditions included hydrostatic consolidation of jacketed granular salt with varying conditions of confining isochoric stress to 38 MPa, temperature to 250 °C, moisture additions of 1% by weight, time duration, and vented and non-vented states. Resultant porosities ranged between 1% and 22%. Optical and scanning electron microscopic techniques were used to ascertain consolidation mechanisms. From these investigations, samples with 1% added moisture or unvented during consolidation, exhibit clear pressure solution processes with tightly cohered grain boundaries and occluded fluid pores. Samples with only natural moisture content consolidated by a combination of brittle, cataclastic, and crystal plastic deformation. Recrystallization at 250 °C irrespective of moisture conditions was also observed. The range and variability of conditions applied in this study, combined with the techniques used to display microstructural features, are unique, and provide insight into an important area of governing deformation mechanism(s) occurring within salt repository applications.

A Very Slow Creep Test on an Avery Island Salt Sample

The applied deviatoric stress during most creep tests performed on salt samples is in the 3.5–20 MPa range. However, the stresses actually experienced in the vicinity of a salt cavern are much smaller. Any extrapolation is difficult to vindicate, as the dominant micro-mechanisms are strongly suspected to be very different in the low-stress and medium-stress domains. To answer this concern, a very slow creep test was performed on an Avery Island salt sample. To minimize the influence of even the smallest of temperature deviations during the test, the testing apparatus was placed in a remote gallery of the Varangeville salt mine, taking advantage of the very stable temperature conditions offered in an underground environment. The test was performed in multiple stages and lasted 42 months. The successive loads of 0.1, 0.2, 0.3, and 0.5 MPa were applied. Measured steady-state strain rates were of the order of 10−12 s−1, which are significantly faster than that extrapolated from creep tests performed at loads ranging between 3.5 and 20 MPa.

Cyclic Loading Effects on the Creep and Dilation of Salt Rock

The Solution Mining Research Institute (SMRI) has embarked on inquiries into the effect cyclic loading might have on salt. This interest stems from the concept of using salt caverns as a storage medium for renewable energy projects such as compressed air energy storage where daily pressure cycles in the cavern are conceivable as opposed to the seasonal cycles that are typical for natural gas storage projects. RESPEC and the Institut fur Aufbereitung und Deponietechnik at Clausthal University of Technology jointly executed a rock mechanics laboratory study using both facilities for performing triaxial cyclic loading creep tests on rock salt recovered from the Avery Island Mine in Louisiana, USA. The cyclic triaxial creep tests were performed under various load paths including compression, extension, and compression/extension. The tests were performed under both dilative and nondilative stress regimes. The cyclic compression creep data were compared to static creep tests performed under similar conditions to assess the effect of cycling of the applied stress. Furthermore, the cyclic compression tests were compared to a numerically simulated static creep test at the same stress and temperature conditions to determine if the creep behavior was similar under cyclic loading.

Leave New Orleans and Discover ‘Real’ Louisiana

Leave New Orleans and Discover ‘Real’ Louisiana

ABSTRACT: Geologic Mapping of Salt Mines in Salt Diapirs; Approaches and Examples from South Louisiana

Abstract Gulf Coast salt diapirs have complex internal structure, which is shown by light and dark layering. The layering reflects variation in anhydrite content and is interpreted to represent highly stretched and sheared depositional bedding. Structure is dominantly vertical, consisting of repeatedly refolded isoclinal folds having vertical plunge. Geologic mapping is conducted primarily as an aid to mine planning and development; separate maps are produced to record basic structure and display the distribution of clastic stringers, sylvite stringers and lenses, crystal size, wet areas, and gas. The latter characteristics, including coarse salt crystals, are anomalous and tend to be associated (in anomalous areas and trends). Gas is a mining hazard, causing Weeks Island and Cote Blanche Island to be classified by MSHA as gassy mines having many associated regulations. Five miners died in a gas explosion at Belle Isle mine in 1979, and blasting is now normally done while the mines are unoccupied (before the morning shift goes in, for example). Water influx, particularly if derived from outside the mine, is a cause of major concern for obvious reasons; at Avery Island a crew is constantly drilling and grouting to maintain control of leaks, and Jefferson Island mine has been lost as a result of flooding when penetrated by an oil rig. Sand reduces the salability of the commercial product and also increases mining costs. The geologic maps provide structural trend information to help the mine engineers avoid undesirable or potentially dangerous areas including those in proximity to the edge of the diapir. They also cast light on the nature of salt diapirism; linear anomalous zones have routinely been interpreted (sometimes with minimal justification) as boundaries between separate salt spines. Map examples from Weeks Island are included.

Creep Modeling of Rock Salts for Geoenvironmental Application

The paper discusses a rate-dependent constitutive model to describe the creep deformation of rock salts. The model is based on the dislocation-related micromechanisms; the concept of effective stress is utilized by incorporating the back stress as an internal variable. The model is used to predict the creep potential of rock salt under general thermo-mechanical loading. The experimental test results from Avery Island dome salt are used in this work. The associated five model parameters are evaluated by using an optimization technique, called “box algorithm.” The parameters are then used with the model to predict unoptimized experimental data sets. The influence of temperature and confining pressure are investigated in detail for the selected rock salt. Overall, excellent correlations are observed.

Rheology of rocksalt

We review progress in experimental determinations of transient and steady-state flow properties and processes of natural rocksalt aggregates, focusing primarily on results from Avery Island, Louisiana, domal salt. The steady-state flow field-established from constant stress and constant strain-rate tests at temperatures from 50 to 200°C, strain rates from 10 −5 to 10 −9 s −1 and differential stresses, σ, from 20.7 to 2.5 MPa-has been separated into two flow regimes, each fit by a power-law relation. At the higher stresses and strain rates this relation is ε ̇ =1.6 ×10 −4 exp( −68.1 RT.10 −3 )σ 5.3 for which the pre-exponential constant is expressed in MPa −5.3 s −1 and the apparent activation energy is in J mol −1. Creep rates predicted by equation (A) do not differ appreciably from those predicted previously. The relatively low stress, low strain-rate data are very well fit by ε ̇ =8.1 ×10 −5 exp( −51.6 RT.10 −3 σ 2.4 which is comparable conditions, predicts creep rates higher and equivalent viscosities lower than does equation (A) by two orders of magnitude. The change in behavior from (A) to (B) is ascribed to a change in rate-limiting mechanism from cross-slip of screw dislocations to the climb of edge dislocations in this dry material. Subgrain formation dominates microstructural development during steady-state flow of salt and, from determinations of average subgrain diameters in crystals from 20 different rocksalt bodies, flow stress levels between 0.6 and 1.4 MPa have been estimated. These values do not bear directly on arguments concerning the nature of forces initiating salt pillow growth because, apparently, evidence relating to the early deformational history has been overprinted. At that stage, fluid-assisted grain boundary diffusional processes might dominate dislocation creep, leading to a linear stress-strain rate mechanical response. Considering buoyancy forces alone, behavior described by equation (B) rather than (A) reduces the relief necessary to initiate pillow growth but a 1000-fold amplification is required to produce stress differences near 1 MPa. That forces other than buoyancy are important is indicated by the occurrence of these same paleostress levels in bedded salts and in shallow offshore concordant intrusions. Differential loading generally provides the most plausible initial driving force for the growth of diapiric salt structures.

Tabasco brand pepper sauce bottles from Avery Island, Louisiana

Archaeologists investigating sites inhabited after 1868 often find bottles that once contained Tabasco brand pepper sauce, manufactured by McIlhenny Company, Avery Island, Louisiana. Detailed information about these bottles is difficult to obtain from the literature. Archaeological research on Avery Island has provided relative dating information about these bottles that will be of interest to historical archaeologists.

E. A. McIlhenny's Black Spiritual Collection from Avery Island, Louisiana

E. A. McIlhenny's Black Spiritual Collection from Avery Island, Louisiana

Simulations of field tests in Avery Island dome salt

Simulations of field tests in Avery Island dome salt

The distribution of trace water around brine leaks in the avery island salt mine: Implications for the natural migration of water in salt

The natural distribution of water in the Avery Island domal salt has been investigated by performing trace water content analysis on 64 samples collected systematically at the 210 and 270 meter levels of the International Salt Compan mine. Specific attention was given to salt near an internal shear zone which is the apparent source of several mine leaks. No discernible migration of brine into the adjacent salt was observed from the meteoric leak at the 210 m level. Extensive water enrichment (>1000 mg/kg) was limited to 30 meters from the formation water leak at the 270 m level. The water contents of coexisting samples near the formation water leak are highly variable. If water is moving from; this leak into the adjacent normal salt it is not doing so by way of a uniform diffusion process. Petrographic examination of polished salt samples reveals that fluid inclusions occur mainly in healed fractures. The water content of a sample depends on the density of such fractures. Natural movement of water in the salt appears to occur mainly through microfractures and possibly along crystal boundaries rather than by the diffusion of brine through crystals. One possible zone of enhanced water content may occur along a possible bedding plane which intersects a mine leak. This suggests that any natural movement of fluid not associated with fractured salt may occur preferentially along bedding planes. The method of brine migration under natural conditions, the occurrence of fluid inclusions (i.e., fracture vs. nonfracture-fill inclusions), and the water content of salt will be helpful in evaluating the migration of brine in response to the thermal and/or pressure gradient which will be created by the emplacement of radioactive waste.

Eustrongylides sp. Epizootic in Young Common Egrets (Casmerodius albus)

In May 1985, epizootic mortality was reported in common egrets (Casmerodius albus) on Avery Island, Louisiana. Subsequent investigation revealed that more than 400 birds died. Severe peritoneal nematodiasis (Eustrongylides sp.) was found on postmortem examination. A nearby breeding rookery on the same island was apparently unaffected. Reasons for this selective mortality are presented. Three other reports of epizootic mortality due to Eustrongylides sp. have been reported. This is the first report of this type of epizootic in gulf-coast birds.

Quaternary Geology of Avery Island, Louisiana: ABSTRACT

Quaternary Geology of Avery Island, Louisiana: ABSTRACT

Room convergence monitoring with an EDM in the Avery Island Salt Mine : Thoms, R L; Gehle, R M Proc 24th US Symposium on Rock Mechanics, College Station, Texas, 20–23 June 1983P849–856. Publ: AEG, 1983

Room convergence monitoring with an EDM in the Avery Island Salt Mine : Thoms, R L; Gehle, R M Proc 24th US Symposium on Rock Mechanics, College Station, Texas, 20–23 June 1983P849–856. Publ: AEG, 1983

Isotopic character and origin of brine leaks in the Avery Island salt mine, south Louisiana, U.S.A.

Twelve brine leaks in the Avery Island salt mine have the isotopic signature of meteoric waters and are isotopically similar to shallow wells around the salt dome. The mine leaks are interpreted as meteoric waters which have penetrated the salt. One leak at the 275 m (∼ 900 ft.) level is drastically enriched in 18O relative to the other waters. This water is similar to 18O-rich waters in other Gulf (of Mexico) coast salt domes and is interpreted as formation water which became incorporated in the salt during diapiric rise of the dome. While water encounterd in other salt domes is primarily formation water, the water encountered in the Avery Island salt is primarily meteoric. This may be related to the shallow depth of the mine, close proximity of the salt top to the surface, absence of caprock, and/or duration and technique of mining.

Stress magnitudes in natural rock salt

Subgrain sizes have been determined for Avery Island domal salt that was deformed experimentally at pressures in the range 3.4 to 20.7 MPa, temperatures from 100° to 200°C, and constant mean principal stress differences of from 2.0 to 20.3 MPa. The subgrain size decreases systematically with increasing stress, independent of temperature, according to the relation d = 190 σ−1, which is in substantial agreement with the work of others on single crystals and poly crystals of synthetic rocksalt. For two‐stage creep experiments it is observed that while subgrain size decreases upon increasing the stress, it does not increase upon lowering the stress. Thus the stresses deduced for seven naturally deformed bedded, domal, and anticlinal rocksalts, 0.5–1.1 MPa, reflect maximum stress differences experienced. The results are applied briefly to considerations of steady state flow during the growth of salt diapirs.

A transient technique for in-situ thermal property measurements

A technique was developed to measure in-situ thermal properties effectively. It makes use of the early transient temperature behavior at the borehole wall in response to the constant heat supply in the borehole. The use of early phase is appropriate since the assumption of cylindrical radial heat flow holds with a good accuracy. To determine the thermal properties of the medium, the theoretical temperature behavior in the Laplace domain was compared with the measured temperature behavior transformed into the Laplace domain. Field data from Avery Island was used for practical application. The obtained thermal properties were subsequently substituted in the nondimensional result given by Carslaw and Jaeger and also used as input parameters in a finite element analysis. The measured temperature behavior was closely reproduced.

Apparatus for determining the thermal properties of large geologic samples at pressures to 0.2 GPa and temperatures to 750 K

An apparatus has been designed and fabricated to measure the thermal diffusivity and thermal conductivity of relatively large geological samples in the pressure range to 0.2 GPa and the temperature range from 300–750 K. Data on a domal salt from Avery Island Mine in Southern Louisiana are presented as examples of the results obtainable from the apparatus.