Pressure drop data for distillation sieve trays have been obtained with experimental trays with small outlet weir heights, including zero, and for trays with small perforations which exhibit large pressure drops due to surface tension. These data have been added to literature data to form a large composite data base with extensive variations in fluid and gas properties, flow rates, and tray designs.A new pressure drop correlation has been developed which retains the use of the dry tray pressure drop, but provides new procedures for estimating liquid inventory and the resistance to vapor flow due to surface tension forces. This correlation gives a mean absolute error of 6.0% and an average error of -0.6%. These errors are significantly less than the errors between measurements and preldictions from two other correlations using the same composite data base. D. L. BENNETT SCOPEPressure drops across distillation column sieve trays should be estimated accurately as part of column designs to determine downcomer backup, column pressure drop, and tray efficiency. These pressure drop calculations become more important in designs for nonfouling service, where small tray spacings are used and flooding limits tray capacity.The objectives of this paper are: a. To determine whether the liquid inventory on a sieve tray can be measured by a tray-mounted manometer, or whether the inventory should be estimated from the total measured pressure drop by subtracting the other pressure drop components.b. To report sieve tray pressure drop data from trays with low outlet weir heights, including zero, and for trays with small perforations which exhibit large surface tension pressure drops.c. To develop a composite data base, consisting of the above data and literature data, which has large variations in fluid and gas properties, flow rates and tray designs.d. To develop a simple pressure drop correlation for sieve trays based on this composite data base, and to compare the accuracy of this correlation with that of several other correlations, using the same data base. CONCLUSIONS AND SIGNIFICANCETray-mounted manometers had been suggested as possible tools for direct measurement of clear liquid head on aerated sieve trays. Time-average measurements made on special trays with fixed liquid inventories showed large discrepancies with known average liquid heads, dependent upon vapor flow rates and clear liquid heads. Therefore, clear liquid heads were determined from total pressure drop measurements from an independent evaluation of surface tension resistance and conventional dry hole pressure drops.Pressure drop data are reported in Table 1 for trays with small weir heights and small perforation sizes. These data were added to literature data to develop a large composite data base with the extensive range of fluid and gas properties, flow rates, and tray designs summarized in Table 2. A pressure drop correlation has been developed using this composite data base. The total pressure drop is assumed to consist of the dry tray component, the liq...

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[1] At Cranfield, Mississippi, United States, a large-scale carbon dioxide (CO 2 ) injection through an injection well (3,080 m deep) was continuously monitored using U-tube samplers in two observation wells located 68 and 112 m east of the injector. The Lower Tuscaloosa Formation injection zone, which consists of amalgamated fluvial point-bar and channel-fill deposits, presents an interesting environment for studying fluid flow in heterogeneous formations. Continual fluid sampling was carried out during the first month of CO 2 injection. Two subsequent tracer tests using sulfur hexafluoride (SF 6 ) and krypton were conducted at different injection rates to measure flow velocity change. The field observations showed significant heterogeneity of fluid flow and for the first time clearly demonstrated that fluid flow evolved with time and injection rate. It was found the wells were connected through numerous, separate flow pathways. CO 2 flowed through an increasing fraction of the reservoir and sweep efficiency improved with time. The field study also first documented in situ component exchange between brine and gas phases during CO 2 injection. It was found that CH 4 degassed from brine and is enriched along the gas-water contact. Multiple injectate flow fronts with high CH 4 concentration arrived at different times and led to gas composition fluctuations in the observation wells. The findings provide valuable insights into heterogeneous multiphase flow in rock formations and show that conventional geological models and static fluid flow simulations are unable to fully describe the heterogeneous and dynamic flow during fluid injection.

Abstract. We discuss the development and calibration of a model for predicting seepage into underground openings. Seepage is a key factor affecting the performance of the potential nuclear-waste repository at Yucca Mountain, Nevada. Three-dimensional numerical models were developed to simulate field tests in which water was released from boreholes above excavated niches. Data from air-injection tests were geostatistically analyzed to infer the heterogeneous structure of the fracture permeability field. The heterogeneous continuum model was then calibrated against the measured amount of water that seeped into the opening. This approach resulted in the estimation of model-related, seepage-specific parameters on the scale of interest.The ability of the calibrated model to predict seepage was examined by comparing calculated with measured seepage rates from additional experiments conducted in different portions of the fracture network. We conclude that an effective capillary-strength parameter is suitable to characterize seepage-related features and processes for use in a prediction model of average seepage into potential waste emplacement drifts.Keywords: capillary barrier, unsaturated zone, parameter estimation * Corresponding author: Fax: +1-510-486-5686; e-mail: SAFinsterle@lbl.gov 2 IntroductionSeepage of water into emplacement drifts for nuclear waste is considered a key factor affecting the long-term safety of a potential repository at Yucca Mountain, Nevada. The number of waste packages contacted by water, the corrosion rate of engineered barriers and waste containers, the dissolution and mobilization of radioactive contaminants, and their release and migration towards the accessible environment all depend on the rate, the chemical composition, and the spatial and temporal distribution of water seeping into the waste-emplacement drifts.Accurately estimating seepage into underground openings excavated from an unsaturated fractured formation requires process understanding on a wide range of scales. Processes to be studied include (1) the mountain-scale distribution of percolation flux, (2) the intermediate-scalechanneling, bifurcation, and dispersion of flow in the fracture network, (3) the small-scale capillary-barrier effect in the boundary layer around the opening, and (4) the micro-scale phenomena of film flow, drop formation, and drop detachment at the drift surface. In addition, the thermodynamic environment in the drift (temperature, relative humidity, ventilation regime, etc.) must be known as it impacts the boundary condition at the drift wall.Developing a comprehensive, physically based seepage model that covers all scales discussed above would require a large amount of characterization data that are difficult or practically impossible to measure in the field. Moreover, a suite of model assumptions would have to be made to relate fracture and surface properties to hydrogeologic model parameters.Finally, the spatial and temporal resolution of a numerical model necessary to accurately and explicitly ca...

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Abstract. The success of geological carbon storage depends on the assurance of permanent containment for injected carbon dioxide (CO2) in the storage formation at depth. One of the critical elements of the safekeeping of CO2 is the sealing capacity of the caprock overlying the storage formation despite faults and/or fractures, which may occur in it. In this work, we present an ongoing injection experiment performed in a fault hosted in clay at the Mont Terri underground rock laboratory (NW Switzerland). The experiment aims to improve our understanding of the main physical and chemical mechanisms controlling (i) the migration of CO2 through a fault damage zone, (ii) the interaction of the CO2 with the neighboring intact rock, and (iii) the impact of the injection on the transmissivity in the fault. To this end, we inject CO2-saturated saline water in the top of a 3 m thick fault in the Opalinus Clay, a clay formation that is a good analog of common caprock for CO2 storage at depth. The mobility of the CO2 within the fault is studied at the decameter scale by using a comprehensive monitoring system. Our experiment aims to close the knowledge gap between laboratory and reservoir scales. Therefore, an important aspect of the experiment is the decameter scale and the prolonged duration of observations over many months. We collect observations and data from a wide range of monitoring systems, such as a seismic network, pressure temperature and electrical conductivity sensors, fiber optics, extensometers, and an in situ mass spectrometer for dissolved gas monitoring. The observations are complemented by laboratory data on collected fluids and rock samples. Here we show the details of the experimental concept and installed instrumentation, as well as the first results of the preliminary characterization. An analysis of borehole logging allows for identifying potential hydraulic transmissive structures within the fault zone. A preliminary analysis of the injection tests helped estimate the transmissivity of such structures within the fault zone and the pressure required to mechanically open such features. The preliminary tests did not record any induced microseismic events. Active seismic tomography enabled sharp imaging the fault zone.

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