Mixing of injected raw (undersaturated) water with brine in Strategic Petroleum Reserve (SPR) salt caverns affects the shape of cavern walls due to leaching. Cavern shape impacts cavern geomechanical stability and available volume for oil storage. Raw water injection occurs during initial solution mining of caverns, remedial leaching of caverns, and oil drawdown. Of interest are factors that control the degree of raw water-brine mixing and thereby the concentration of the aqueous fluid mixture that contacts the salt cavern walls. It is hypothesized that poorly-mixed fresh water could potentially cause undesirable and non-uniform leaching , for example, if buoyant poorly-mixed fresh water collects and preferentially leaches under the oil-brine interface . This report presents current understanding of controls on incomplete-to-complete mixing of raw water and brine, focusing on implications for SPR cavern leaching. In the context of mixing, we review the following: SPR leaching operations; models of leaching; field measurements of leaching and cavern shapes; and previous laboratory experiments of mixing and /or leaching performed at Sandia National Laboratories. We present recent laboratory experiments in 2014-2016 that focused explicitly on understanding controls of poor-to-well mixed conditions. We find that well-mixed conditions are expected for typical operating conditions of the SPR.
Temperature monitoring is essential in automation, mechatronics, robotics and other dynamic systems. Wireless methods which can sense multiple temperatures at the same time without the use of cables or slip-rings can enable many new applications. A novel method utilizing small permanent magnets is presented for wirelessly measuring the temperature of multiple points moving in repeatable motions. The technique utilizes linear least squares inversion to separate the magnetic field contributions of each magnet as it changes temperature. The experimental setup and calibration methods are discussed. Initial experiments show that temperatures from 5 to 50 °C can be accurately tracked for three neodymium iron boron magnets in a stationary configuration and while traversing in arbitrary, repeatable trajectories. This work presents a new sensing capability that can be extended to tracking multiple temperatures inside opaque vessels, on rotating bearings, within batteries, or at the tip of complex endeffectors.
A study was undertaken to determine the viscosity of liquefied 20 lb/ft3 poly methylene diisocyanate (PMDI) foam and the stress required to puncture solid PMDI foam at elevated temperatures. For the rheological measurements the foam was a priori liquefied in a pressure vessel such that the volatiles were not lost in the liquefaction process. The viscosity of the liquefied PMDI foam was found to be Newtonian with a power law dependence on temperature log10(μ/Pa s) = 20.6 – 9.5 log10(T/°C) for temperatures below 170 °C. Above 170 °C, the viscosity was in the range of 0.3 Pa s which is close to the lower measurement limit (≈ 0.1 Pa s) of the pressurized rheometer. The mechanical pressure required to break through 20lb/ft3 foam was 500-800 psi at temperatures from room temperature up to 180 °C. The mechanical pressure required to break through 10 lb/ft3 was 170-300 psi at temperatures from room temperature up to 180 °C. We have not been able to cause gas to break through the 20 lb/ft3 PMDI foam at gas pressures up to 100 psi.
This report consolidates technical information on several materials and material classes for a fire assessment. The materials include three polymeric materials, wood, and hydraulic oil. The polymers are polystyrene, polyurethane, and melamine- formaldehyde foams. Samples of two of the specific materials were tested for their behavior in a fire - like environment. Test data and the methods used to test the materials are presented. Much of the remaining data are taken from a literature survey. This report serves as a reference source of properties necessary to predict the behavior of these materials in a fire.
A model system was developed for enabling a multiscale understanding of centrifugal-contactor liquid–liquid extraction.The system consisted of Nd(III) + xylenol orange in the aqueous phase buffered to pH =5.5 by KHP, and dodecane + thenoyltrifluroroacetone (HTTA) + tributyphosphate (TBP) in the organic phase. Diffusion constants were measured for neodymium in both the organic and aqueous phases, and the Nd(III) partition coefficients were measured at various HTTA and TBP concentrations. A microfluidic channel was used as a high-shear model environment to observe mass-transfer on a droplet scale with xylenol orange as the aqueous-phase metal indicator; mass-transfer rates were measured quantitatively in both diffusion and reaction limited regimes on the droplet scale. Lastly, the microfluidic results were comparable to observations made for the same system in a laboratory scale liquid–liquid centrifugal contactor, indicating that single drop microfluidic experiments can provide information on mass transfer in complicated flows and geometries.
Metastable water-in-crude-oil emulsion formation could occur in a Strategic Petroleum Reserve (SPR) cavern if water were to flow into the crude-oil layer at a sufficient rate. Such a situation could arise during a drawdown from a cavern with a broken-hanging brine string. A high asphaltene content (> 1.5 wt %) of the crude oil provides the strongest predictor of whether a metastable water-in-crude-oil emulsion will form. However there are many crude oils with an asphaltene content > 1.5 wt % that don't form stable emulsions, but few with a low asphaltene content that do form stable emulsions. Most of the oils that form stable emulsions are "sour" by SPR standards indicating they contain total sulfur > 0.50 wt %.