Chemical Characterization of Geothermal Water Produced by 4699 CIGHID Well and Its Behaviour Under Inhibitor Treatment
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Proceedings World Geothermal Congress 2005 Antalya, Turkey, 24-29 April 2005 Chemical Characterization of Geothermal Water Produced by 4699 CIGHID Well and its Behaviour under Inhibitor Treatment Mioara Sebeşan, Oana Stănăşel and Radu Sebeşan University of Oradea, Str. Armatei Romane nr.5, Oradea, Romania [email protected], [email protected] , rsebesan @uoradea.ro Keywords: well, treatment with inhibitors, Starting 1998 geothermal energy from Cighid was used to tripolyphosphate heat up water and for heating the hospital ABSTRACT A part of the water has balnear use in a small, open swimmng pool. This study presents the chemical composition of water produced by 4699 well in CIGHID, water which is used as In 2001 a flowrate of medium 1,5 l/s was exploited (at a 3,0 secondary agent in the heating system of a hospital for bars dynamic pressure in exploited head), the whole children with handicap. extracted volume was aproximately 44 000 m3. A deposition tendency of the minerals from this water was Artezian sprinckled geothermal water is led - on exploited noticed. There were made chemical analysis of solid head pressure – throrgh beneficiary heat – exchangers, from depositions, first before and then after chemical injection. where is overflowed beside used waters and meteoric waters in the water treatment station of the complex. From 1. INTRODUCTION there the water is pumped in Crisul rivers inlet befor its 4699 geothermal well is situated in the yard of the hospital junction with „ Crişul Negru” river. for children with severe handicap from CIGHID, located at The maximum production of geothermal water from the about 3,5 km south-west from GHIORAC town and 4 km 3 3 far from CIUMEGHIU village. deposit is 8 l/s (28,8 m /h) which represents a 250000 m yearly volume able to supply ( a temperature error of 0 From geological point of view CIGHID area has a ∆∆=45 C ) 11300 Gcal/ an. crystalline bottom (mica schist, quartz schist) above which are discontinuous fallen out Pliocene settling formation. The yard of geothermal well needs neither a cold water connection nor a sewage, because there is no employed Inferior panonian – developed under 1060 m depth – is staff. Also, feeding with electrical energy isn’t necessary. basicly represented by breccia and marly lime sandstone and in upper part by marls, sabulons marls with sandstone Transmission pipe of geothermal water through heat interlayer. Drilling stoped with the bottom at 2240 m depth exchangers has 5 in diameter, it is burried at 1,5 m in the without coming out from inferior panonian. soil and it is preisolated. Upper panonian (1060 – 96) starts with a quick The work programme aproved by exploitation licence 1264 sedimentation in cycles, with alternation in order of meters, from march 2000 stipulated that all the required of marls, clays and sands with different degrees of interventions for 4699 CIGHID well reconditioning will be contamination. Filling sedimentation of Panonian done in order to obtain the necessary data for deposits depression ends with llake, delta and river meadow type evaluation and future usage in industrial exploitation .All formation of quaternary age. geothermal water installations will be accuratly made for prevention of leakages, which could affect the soil or Multi – bedded geothermal aquiferous from the interest area phreatic water. is part of regional hydro – geothermal system of inferior pliocene with is disposed in all central area of West Plain According to the data and information obtained in the (ZEKIND, CIUMEGHIU, SALONTA, TINCA, CEFA). experimental exploitation phase of 4699 CIGHID well drilling it will be established the opportunity of Hydro – dynamics and physico – chemical parameters achievement – for the industrial exploitation of the deposit present some differences, depending on granulometry, on – of a geothermal point equiped with scale prevent subsidence depth and on compaction degree, on installation, with heat – exchangers and separators, approaching to frame as well on the way of opening and captation and drying with combustion gase installations. producing. It's̉ about an aquiferous with large horizontal extension, which affects the all pile of inferior pliocene and 2. EXPERIMENTAL DATA AND DISCUSSIONS which is in effect, lacking of feeding. 2.1 Chemical composition of geothermal water 4699 CIGHID well was drilled and tested in 1997 by In this study was determined chemical composition of S.C.TRANSGEX S.A. It is cased off a hale with a 133/8 geothermal water produced by 4699 CIGHID well. (Franco, inch (0 – 300 m) column tower wich is joint with 95/8 inch and Olafsson, 1991) (300 – 1200 m) wholly cemented, and with a 51/2 inch (0 – 1967 m). It has been producing from 1695 - 1894 m depth The methods of analysis are presented as follows: interval open by grips (111 m) geothermal water with 85ºC temperature, 4,27 g/l mineralization and a maximum 8 l/s flowrate. 1 Sebeşan et al. Determination of hydrogen sulphide (Babko and dissolved constituents the samples must be filtered and Pilipenko,1974) acidified with 4 ml of suprapure HNO3 per liter of sample. A Cs-La solution is added to samples, blank and standard H2S determination was made by titration with Hg-acetate in presence of dithizone. In this purpose 45 ml of sample were solutions. Ionization should be controlled by the addition of combined with 5 ml of 5N NaOH solution in a volumetric Cs-La solution and oxysalt interference on calcium is flask. This content was added to 5 ml acetone into an reduced. The solutions are directly aspirated into an Erlenmeyer flask. The solution was then titrated with oxidizing air-acetylene flame. Absorptions are read at 589.6 nm for sodium, at 766.5 nm for potassium, at 285.2 nm for (H3CCOO)2Hg in presence of small grain of solid dithizone. During titration a black precipitate of HgS forms. magnesium and at 422.7 nm for calcium. The endpoint is recorded when the colour changes from the yellow colour of dithizone in alkaline solution to the red The results are presented in Table 1. colour of the Hg-dithizonate. If the concentration of hydrogen sulphide is high the sample becomes yellowish Table 1. Chemical composition of geothermal water brown and even black during titration. This is caused by the from 4699 CIGHID well, in mg/l HgS precipitate and makes the endpoint uncertain. In this case is better to reduce the volume of the sample. PH 8,6 245,0 Cl- Determination of chloride (Trujillo, et. al, 1987) The analysis was made by titration with silver-nitrate Mineralization 4273 solution, 0.01M, using potassium chromate as indicator. 2- The colour changes from yellow to brown, but the colour SO4 56,0 change is very difficulty to identify. Before titration the pH must be checked to be above 8.2. If it is not, 1N NaOH solution is added drop by drop. 2745,0 HCO3 Determination of sulphate (Trujillo, et. al, 1987) Na+ 1188,0 The analysis was made by precipitation with barium perchlorate in presence of thorin. The method is based on + the titration of the exces of barium perchlorate solution Ca 20,0 until the first colour change from yellow to pink. Mg2 5,0 Determination of carbon dioxide (Babko and Pilipenko,1974) SiO 42 The analysis is made by titration. The water sample is 2 treated with a mineral acid. The free carbon dioxide, the released CO2 from carbonates and bicarbonates are drawn Fe2 O 3 + into air and absorbed in a 0.02 N Ba(OH)2 solution. After A12O3 the formed precipitated is filtered, the exces of Ba(OH)2 is 14,0 titrated with 0.02N HCl by using phenolphtaleina as indicator. Determination of phenols was made by using Phenols 4,16 spectrophotometric method. The absorptions were read at 435nm. Dissolved gases O2 2,90 H S 2,04 Determination of silica (Trujillo, et. al, 1987) 2 The spectrophotometric method is based on the reaction of C0 2,20 silica with molybdate ions at pH of 1.2-1.5. A yellow silico- 2 molibdate complex is formed. If the concentration of silica in thermal water is higher than 100 ppm, the silica can polymerize and the polymerized silica will not react with Silica from geothermal waters presents a variable solubility molybdate. Treatment with alkali converts it all to the function of temperature. monomeric state. The adopted procedure covers the concentration range of 20-500 ppm. Higher concentrations It is known that silicon is an universal element spread in the can be determined by taking smaller aliquots. A ground in shape of many combinations. Its solubility in disadvantage of this method is the instability of colour of waters depends on several factors such as: the nature of the solution. For this reason the samples and the standards combination in which silicon is found, the mineral content must be prepared at the same time and the absorption must solved in water, water pH and temperature. be read 10-60 minutes after developing the colour. High concentration of hydrogen sulphide may reduce the We wish to treat the band between silicon content from silicomolybdate complex to molybdenum blue. This can be geothermal waters exprimed in silica and the temperature of prevented by oxidizing the sulphide with iodine. geothermal waters. Later, we found in literature too, a serial articles in which our ipotesis is confirmed, even more, they Determination of sodium, potassium, magnesium and have been built apparatus detecting silica in purpose to calcium (Trujillo, et. al, 1987) measure well s temperature. The analysis of these components were made by atomic Therefore, from the literature it is known the use of silica absorption spectroscopy. For the determination of these content as relative indicator of temperature.