Showing papers on "Brine published in 2005"

100th Anniversary Special Paper: Vapor Transport of Metals and the Formation of Magmatic-Hydrothermal Ore Deposits

Abstract: In most published hydrothermal ore deposit models, the main agent of metal transport is an aqueous liquid. However, there is increasing evidence from volcanic vapors, geothermal systems (continental and submarine), vapor-rich fluid inclusions, and experimental studies that the vapor phase may be an important and even dominant ore fluid in some hydrothermal systems. This paper reviews the evidence for the transport of metals by vapor (which we define as an aqueous fluid of any composition with a density lower than its critical density), clarifies some of the thermodynamic controls that may make such transport possible, and suggests a model for the formation of porphyry and epithermal deposits that involves precipitation of the ores from vapor or a vapor-derived fluid. Analyses of vapor (generally >90% water) released from volcanic fumaroles at temperatures from 500° to over 900°C and near-atmospheric pressure typically yield concentrations of ore metals in the parts per billion to parts per million range. These vapors also commonly deposit appreciable quantities of ore minerals as sublimates. Much higher metal concentrations (from ppm to wt %) are observed in vapor inclusions trapped at pressures of 200 to 1,000 bars in deeper veins at lower temperatures (400°–650°C). Moreover, concentrations of some metals, notably Cu and Au, are commonly higher in vapor inclusions than they are in inclusions of coexisting hypersaline liquid (brine). Experiments designed to determine the concentration of Cu, Sn, Ag, and Au in HCl-bearing water vapor at variable although relatively low pressures (up to 180 bars) partly explain this difference. These experiments show that metal solubility is orders of magnitude higher than predicted by volatility data for water-free systems, and furthermore that it increases sharply with increasing water fugacity and correlates positively with the fugacity of HCl. Thermodynamic analysis shows that metal solubility is greatly enhanced by reaction of the metal with HCl and by hydration, which results in the formation of species such as MeCl m . n H2O. Nonetheless, the concentrations measured by these experiments are considerably lower than those measured in experiments involving aqueous liquids or determined for vapor fluid inclusions. A possible explanation for this and for the apparent preference of metals such as Cu and Au for the vapor over the coexisting brine in some natural settings is suggested by limited experimental studies of metal partitioning between vapor and brine. These studies show that, whereas Cu, Fe, and Zn all partition strongly into the liquid in chloride-bearing sulfur-free systems, Cu partitions preferentially into the vapor in the presence of significant concentrations of sulfur. We therefore infer that high concentrations of Cu and Au in vapor inclusions reflect the strong preference of sulfur for the vapor phase and the formation of sulfur-bearing metallic gas species. Phase stability relationships in the system NaCl-H2O indicate how vapor transport of metals may occur in nature, by showing a range of possible vapor evolution paths for the conditions of porphyry-epithermal systems. At the world-class Bingham Canyon porphyry Cu-Au deposit, evidence from fluid inclusions supports a model in which a single-phase fluid of intermediate to vapor-like density ascends from a magma chamber. On cooling and decompression, this fluid condenses a small fraction of brine by intersecting the two-phase surface on the vapor side of the critical curve, without significantly changing the composition of the expanding vapor. Vapor and brine reach Cu-Fe sulfide saturation as both phases cool below 425°C. Vapor, which is the dominant fluid in terms of the total mass of H2O, Cu, and probably even Cl, is interpreted to be the main agent of metal transport. The evolution of fluids leading to high-grade epithermal gold mineralization is initiated by an H2S-, SO2-, Au-, and variably Cu- and As-rich vapor, which separates from an FeCl2-rich brine in a subjacent porphyry environment. In the early stages of the hydrothermal system, vapor expands rapidly and on reaching the epithermal environment, condenses, producing hypogene advanced argillic alteration and residual vuggy quartz and, in some cases, coeval high-sulfidation precious metal mineralization (e.g., Pascua). More commonly, the introduction of precious metals occurs somewhat later, after the site of magmatic fluid exsolution has receded to greater depth. Because of the relatively high pressure, the vapor separating from brine at this stage cools along a pressure-temperature path above the critical curve of the system, causing it to contract to a liquid capable of transporting several parts per million Au to temperatures as low as 150°C.

Interfacial Tensions of the Crude Oil + Reservoir Brine + CO2 Systems at Pressures up to 31 MPa and Temperatures of 27 °C and 58 °C

Abstract: An experimental technique is developed to measure the interfacial tensions of the crude oil + reservoir brine + CO2 systems at pressures from (0.1 to 31.4) MPa and two temperatures (27 and 58) °C using the axisymmetric drop shape analysis (ADSA) technique for the pendant drop case. The measured dynamic interfacial tension is gradually reduced to an equilibrium value. For both the reservoir brine + CO2 system and the crude oil + CO2 system, the equilibrium interfacial tension decreases as the pressure increases, whereas it increases as the temperature increases. For the reservoir brine + CO2 system, the interfacial tension data are not available at P ≥ 12.238 MPa and 58 °C because the pendant brine drop cannot be formed in the CO2 phase. However, for the crude oil + CO2 system, the equilibrium interfacial tension remains almost constant at P ≥ 8.879 MPa and 27 °C or at P ≥ 13.362 MPa and 58 °C. Under the same conditions, nevertheless, the equilibrium interfacial tension of the crude oil + reservoir brine +...

Mixing of Sodic and Calcic Brines and Uranium Deposition at McArthur River, Saskatchewan, Canada: A Raman and Laser-Induced Breakdown Spectroscopic Study of Fluid Inclusions

Abstract: The richest U deposit in Saskatchewan, Canada, occurs in the McArthur River area, in the vicinity of the unconformity between the Athabasaca sandstones and an Archean to lower Proterozoic basement. Paleofluids related to the silicification of the sandstones and the formation of pre- and postore cements in breccias were studied using microthermometry, Raman microspectroscopy, and laser induced breakdown spectroscopy (LIBS) on individual fluid inclusions. A detailed reconstruction of the fluid composition in the system Na-Ca-Mg-Cl shows that two types of brines are responsible for the main quartz cements: an NaCl-rich brine (25 wt % NaCl, up to 14 wt % CaCl 2 , and up to 1 wt % MgCl 2 ), which is interpreted as a primary formation water that was expelled from bedded evaporites; and a CaCl 2 -rich brine (5–8 wt % NaCl, 20 wt % CaCl 2, and up to 11 wt % MgCl 2 ), which is considered to have formed during the interaction between the NaCl-rich brine and Ca-rich minerals in the basement and was introduced into the fault system and mixed with the NaCl-rich brine during the critical stage of U deposition. The pressure-temperature conditions of formation of the quartz cements are estimated to be 1,200 to1,400 bars and 190° to 235°C for the silicification events during the preore stage, and 500 to 900 bars after a pressure decrease from lithostatic conditions and slightly lower temperatures due to the mixing of the NaCl-rich brine with the cooler (approx 140°C) CaCl 2 -rich brine during the main stage of breccia sealing. Temperature and pressure drops combined with the effects of brine mixing appear to be key factors for the main stages of quartz cementation and U deposition at the McArthur deposit.

Brine rejection from freezing salt solutions: a molecular dynamics study.

Abstract: The atmospherically and technologically very important process of brine rejection from freezing salt solutions is investigated with atomic resolution using molecular dynamics simulations The present calculations allow us to follow the motion of each water molecule and salt ion and to propose a microscopic mechanism of brine rejection, in which a fluctuation (reduction) of the ion density in the vicinity of the ice front is followed by the growth of a new ice layer The presence of salt slows down the freezing process, which leads to the formation of an almost neat ice next to a disordered brine layer

Geophysical and geochemical signatures of Gulf of Mexico seafloor brines

Abstract: . Geophysical, temperature, and discrete depth-stratified geochemical data illustrate differences between an actively venting mud volcano and a relatively quiescent brine pool in the Gulf of Mexico along the continental slope. Geophysical data, including laser-line scan mosaics and sub-bottom profiles, document the dynamic nature of both environments. Temperature profiles, obtained by lowering a CTD into the brine fluid, show that the venting brine was at least 10°C warmer than the bottom water. At the brine pool, thermal stratification was observed and only small differences in stratification were documented between three sampling times (1991, 1997 and 1998). In contrast, at the mud volcano, substantial temperature variability was observed, with the core brine temperature being slightly higher than bottom water (by 2°C) in 1997 but substantially higher than bottom water (by 19°C) in 1998. Detailed geochemical samples were obtained in 2002 using a device called the "brine trapper" and concentrations of dissolved gases, major ions and nutrients were determined. Both brines contained about four times as much salt as seawater and steep concentration gradients of dissolved ions and nutrients versus brine depth were apparent. Differences in the concentrations of calcium, magnesium and potassium between the two brine fluids suggest that the fluids are derived from different sources, have different dilution/mixing histories, or that brine-sediment reactions are more important at the mud volcano. Substantial concentrations of methane, ammonium, and silicate were observed in both brines, suggesting that fluids expelled from deep ocean brines are important sources of these constituents to the surrounding environment.

On laboratory simulation and the temperature dependence of the evaporation rate of brine on Mars

Abstract: [1] We have determined the evaporation rate of brine under simulated martian conditions at temperatures from 0°C to −26.0°C as part of our efforts to better understand the stability of water on Mars. Correcting for the effect of water build-up in the atmosphere and the lower gravity on Mars relative to Earth we observed a factor of almost 30 decrease in evaporation, from 0.88 mm/h at ∼0°C to 0.04 mm/h at −25.0°C. The results are in excellent agreement with the predictions of Ingersoll's (1970) theoretical treatment, lending support to the theory and our procedures. Thus brine formation will increase the stability of water on Mars not only by extending the liquid temperature range, but also by considerably decreasing the evaporation rate.

Well treating compositions containing water superabsorbent material and method of using the same

Abstract: A well treating composition containing a polysaccharide-based water-superabsorbent material has particularly applicability as a thermal insulating, fracturing or acid stimulation fluid. The water-superabsorbent material is capable of absorbing, at a minimum, its own weight. Particularly effective are biodegradable materials containing guar gum and carrageenan. The composition may further contain a crosslinking agent, brine and/or a viscosifying polymer or a gelling agent. As an oil-based fluid, the crosslinking agent is absorbed onto the water-superabsorbent material and serves to effectively delay crosslinking.

Mechanism for salt scaling of a cementitious surface

Abstract: Freezing and thawing of concrete in the presence of deicer salts results in superficial damage known as salt scaling. Scaling damage consists of the removal of small flakes from the surface, leaving the body susceptible to water and ion ingress, thus posing a significant threat to the durability of the body. None of the proposed mechanisms for salt scaling account for all of the phenomenology observed during previous studies. We report a novel experimental method designed to measure the stress that arises when a solution is frozen on a cementitious plate. These experiments reveal a thermal expansion mismatch (or, bimaterial) mechanism that accounts for all of the observed salt scaling phenomenology. According to the bimaterial mechanism, scaling occurs when the stress in the freezing layer rises above the tensile strength of the brine-containing ice, resulting in cracking. A viscoelastic analysis of the stresses in the brine/ice layer shows that pure ice would not crack, but a layer containing >1% NaCl would. The damage from cracking of the ice is exacerbated by weakening of the cement paste by exposure to concentrated brine.

Ammonia/co2 refrigeration system

Abstract: An ammonia/CO2 refrigeration system having a liquid pump for feeding the liquid CO2 cooled in a brine cooler by the utilization of the vaporization latent heat of ammonia in an ammonia refrigeration cycle to a cooler, which comprises a liquid receiving vessel (4) for receiving a CO2 brine cooled in a brine cooler (3), a liquid pump (5) capable of changing the rate of the feed of a liquid, a rising piping (90) provided between the liquid pump (5) and a cooler (6), and a communication pipe (100) for communicating the top of the rising piping (90) with the CO2 gas phase in the liquid receiving vessel (4), wherein the discharge pressure of the liquid pump (5) is set so as for the CO2 recovered from the cooler (6)to return to a brine cooler (3) or the liquid receiver (4) in the state of a liquid or a gas-liquid mixture, and the level of the rise in the rising piping (90) is set at a level being the same as or higher than the highest storage level for the CO2 brine in the liquid receiving vessel (4). The above ammonia/CO2 refrigeration system allows a refrigeration cycle of a combination of an ammonia cycle and a CO2 cycle to be formed with no care, even when a refrigerating show case, which is the cooler side of the CO2 cycle, is installed at an arbitrary place.

Method of unloading and vaporizing natural gas

Abstract: A method and apparatus for unloading natural gas (NG), including gasifying liquid and/or compressed NG using the latent heat of water and propane, and/or storing liquid or compressed NG gas in a storage cavern system that utilizes a buffer layer to prevent hydrating the NG gas, the storage cavern system being configured such that the NG may be forced out of a first storage chamber by increasing the amount of brine in a second chamber to displace a buffer fluid located therein such that the displace buffer fluid enters the first storage chamber and displaces the NG, as well as the processes for compressing, chilling and/or liquefying quantities of LNG and transporting those volumes to markets for redelivery.

High density brines for use in wellbore fluids

Abstract: A composition and method for use in drilling or completing a subterranean well comprising a solidsfree, high-density brine composed of alkali metal polytungstate and blends thereof. These high-density brines are also useful as wellbore fluids and other non-oilfield fluids requiring high density properties.

The effects of salt type and salinity on formation water viscosity and nmr responses

Abstract: Reservoir water salinity and viscosity are important parameters for formation evaluation and production. For log analysts, salinity is critical to resistivity-based saturation estimation. It is well understood that water salinity affects its viscosity and diffusivity, which, in turn, affects Nuclear Magnetic Resonance (NMR) relaxation time estimation and NMR-based log interpretation. For production engineers, the ability to measure the formation water viscosity is important for enhanced oil recovery because water viscosity affects the CO2 injection via the effective permeability. The formation water viscosity in sedimentary rocks can vary by one order of magnitude for different types and concentrations of salts. Previous studies on formation water properties have focused on NaCl and KCl, the two most common brines in connate water and in water-based drilling mud. The common practice in formation evaluation is to treat the physical properties of non-NaCl brines by a phenomelogical NaCl-equivalent quantity. While this approach may be reasonable for the estimation of brine resistivity, the viscosities of NaCl and KCl follow a different salinity trend. In fact, viscosity versus salinity behaves differently for different saline types. Three factors contribute to the viscosity of the ionic solution: Brownian motion, DebyeHuckel interaction (electrostatic potential due to all other ions surrounded), and structural temperature effect (the structural tightening or loosening due to hydrated or unhydrated ions, respectively). The Brownian motion and the Debye-Huckel interaction always contribute positively to the viscosity of any brine. The structural temperature effect, however, alters the viscosity of brine either positively or negatively depending on the type of salts. Until now, this effect has not been recognized for brines of interest within the formation evaluation community. We found the solute composition of formation water plays an important role in determining its viscosity and diffusivity with varying salt concentration. By considering the structural temperature effect of brine components and using our experimental data on various brines, we are able to predict the viscosity and diffusivity of a large suite of brine types over a selected temperature range that more accurately compares with the previous correlations and does not consider the structural temperature effect. Furthermore, our

Methods of Using Settable Compositions in a Subterranean Formation

Abstract: The present invention relates to settable compositions that comprise magnesium oxide and at least one divalent salt and associated methods of use. In some embodiments, the present invention discloses methods of a forming a hardened mass comprising providing a settable composition comprising magnesium oxide, and a brine comprising water and a divalent salt; placing the settable composition into a desired location; and allowing the settable composition to set to form the hardened mass. In other embodiments, the present invention discloses methods of forming a hardened mass in a subterranean formation comprising placing a brine comprising water and a divalent salt into the subterranean formation; contacting the brine with magnesium oxide; and allowing the brine and the magnesium oxide to react to form the hardened mass. In other embodiments, the present invention discloses methods forming a casing in a well bore, and converting a drilling fluid to a settable composition.

Method of combined extraction of magnesium and lithium in salt lake bittern

Abstract: A process for extracting Mg and Li from the brine of salt lake features that the ammonia and ammonium dicarbonate are used to implement two stages of magnesium deposition. For the first stage, the crystal seeds (5-10%) are added and the efficiency of magnesium deposition is controlled to 80-85%. For the second stage, the solid ammonium dicarbonate is added for reaction to obtain more than 98% of Mg extraction rate. The ammonium chloride in the mother liquid can be converted to ammonia for reuse. The lithium chloride solution enriched from the mother liquid can be used to prepare lithium carbonate. The extraction rate of Li is more than 95%.

Numerical modeling of carbon dioxide injection and transport in Deep Saline Aquifers

Abstract: Publisher Summary This chapter describes the development of a compositional reservoir simulator capable of modeling multiphase transport of carbon dioxide (CO2) in brine aquifers. As an example, it considers the radial injection of supercritical CO2 in a brine aquifer, and results are provided that illustrate the evolution of a 2-phase fluid system in which the injected CO2 resides in a dense supercritical phase and also dissolves into the liquid phase. Salt precipitation into a solid phase is found to occur close to the injection well where the gas phase dominates. To determine the feasibility of deep aquifer sequestration it is necessary to have a numerical model that can accurately predict the fate of CO2 under the conditions of interest. Conditions that support the existence of supercritical CO2 should be present at depths greater than about 800 m where pressure and temperature would be above the critical point of CO2.