34 research outputs found
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Solvent extraction of methane from simulated geopressured-geothermal fluids: sub-pilot test results
The extraction of methane dissolved in 15 wt % sodium chloride solution at 150/sup 0/C and 1000 psi has been demonstrated using n-hexadecane as the solvent in a sub-pilot scale extraction column operated in a continuous, countercurrent flow mode. Greater than 90% recovery of methane was obtained with solvent/brine mass flow ratios in the range of .040 to .045. The height of an ideal stage in this experimental Elgin-type spray column is estimated to be 1.5 ft. Application of this process on actual geopressured fluids is technically feasible, and when combined with direct drive injection disposal is economically attractive. Design and operation of a methane saturated-brine supply system to provide simulated geopressured fluid continuously at 150/sup 0/C and 1000 psi are also described
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Potential methods for methane extraction from geopressured brine at high temperature and pressure
Recovery of methane from Gulf Coast geopressured-geothermal reservoirs does not appear to be profitable without a rise in natural gas prices to offset high production costs. If injection into the production reservoir becomes necessary to maintain productivity and to minimize subsidence, the injection pumping costs approach and even exceed the value of the recoverable methane. An option aimed at reducing the injection pump operating costs is to maintain a higher than normal pressure at the production wellhead to reduce the injection-pumping work load. This option, however, is considerably less attractive if that portion of methane still dissolved at elevated pressure cannot be recovered. Therefore, there is a strong incentive to devise methods for extracting methane at high pressures and temperatures. Liquid extraction with a very low water-soluble organic is a technically feasible method and looks promising as an applicable process. A candidate solvent is hexadecane, a paraffinic hydrocarbon with the necessary phase-equilibrium thermodynamic properties to satisfy the technical requirements for such an operation, without any obvious economic barriers. Gas stripping is another technically feasible method, but the economics do not look favorable because of gas dissolution losses. Freon refrigerants were considered because of their ease of product-stripping gas separation and nitrogen was considered because of its low cost. Brine-driven positive displacement pumps with provisions for methane exsolution are technically feasible concepts and could eliminate or greatly reduce pump power costs. These extraction operations will not preclude the option of recovering the thermal energy component, if desired
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Methane extraction from geopressured-geothermal brine at wellhead conditions
Disposal of geopressured-geothermal brine effluents by injection is expected to be costly, even into shallow aquifers. If injection into the production reservoir becomes necessary to maintain productivity and to minimize subsidence, the injection pumping costs can become overwhelming. An option aimed at reducing injection pump operating costs is to maintain a higher than normal pressure at the production wellhead to reduce the injection pumping load. The crucial element, however, is that a significant portion of CH/sub 4/ remains in solution and must be recovered in order for the pressure maintenance option to be cost effective. A laboratory and field test capability has been established, and several methods for extracting dissolved CH/sub 4/ at high temperature and pressure are being evaluated. Solvent extraction and use of hydraulic motors or turbines coupled to CH/sub 4/ recovery systems are the leading candidate methods
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On-line tests of organic additives for the inhibition of the precipitation of silica from hypersaline geothermal brine IV. Final tests of candidate additives
The Lawrence Livermore Laboratory Brine Treatment Test System at Niland, Imperial Valley, California, has been used to evaluate a number of cationic polymers and surfactants as scale control agents. An initial group of compounds was narrowed to four on the basis of their activity as silica precipitation inhibitors. Three of these and certain combinations of compounds were then given a 40-h test to determine their effectiveness in retarding scales formed at 220, 125, and 90/sup 0/C. The best single compound was Corcat P-18 (Cordova Chemical Co. polyethylene imine, M.W. approx. = 1800). It had no effect on the scale at 220/sup 0/C, but it reduced the scales at 125 and 90/sup 0/C by factors of 4 and 18, respectively, and it also has activity as a corrosion inhibitor. Other promising compounds are PAE HCl (Dynapol poly(aminoethylene, HCl salt)), which also somewhat reduces the 220/sup 0/C scale; Ethoquad 18/25 (Armak methyl polyoxyethylene(15) octadecylammonium chloride); and Mirapol A-15 (a Miranol Chemical polydiquaternary compound). The best additive formulation for the brines of the Salton Sea Geothermal Field appears to be a mixture of one of these silica precipitation inhibitors with a small amount of hydrochloric acid and a phosphonate crystalline deposit inhibitor. Speculations are presented as to the mechanism of inhibition of silica precipitation and recommendations for further testing of these additives
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Tests of proprietary chemical additives as antiscalants for hypersaline geothermal brine. Final report
The Lawrence Livermore Laboratory brine treatment test system has been used to carry out a short-term evaluation of a number of proprietary chemical additives as antiscalants for the hypersaline brine of the Salton Sea Geothermal Field. In addition, a test of sludge seeding was conducted as a technique for scale control. The effect of each additive on the rate of precipitation of silica from the effluent brine at 90/sup 0/C was measured, and scaling rates of brine treated with nine of the additives were measured at 125 and 210/sup 0/C. Corrosion rates of mild steel in the treated brines were estimated using Petrolite linear polarization resistance equipment. None of the additives had a direct effect on the rates of silica precipitation, and none had a beneficial effect on the scale formed at 210/sup 0/C. At 125/sup 0/C, two additives, Drewsperse 747 (Drew Chemical) and SC-210 (Southwest Specialty Chemicals) afforded a marginal degree of scale reduction. The Austral-Erwin additive diminished the adherence of scale formed at points of high velocity fluid flow but increased solids accumulation at other points. Sludge seeding shows some promise because it reduces the degree of silica supersaturation of the brine. Results of analyses of solids precipitated from effluent brines (Woolsey No. 1 and acidified Magmamax No. 1) are presented