Hidrológiai Közlöny 1947 (27. évfolyam)

1-4. szám - TUDOMÁNYOS INTÉZETEINK KUTATÓ MUNKÁJA

36 HIDROLÓGIAI KÖZLÖNY XXVII. évf. 191,7. l—l,, szám. hole has been ope'n without casing, permeability and porosity data of the reservoir rock, etc. are all of importance. It is advisable to take the sample when the consolidation of water components has been definitely established and then the analysis can be made with the widely used colorimetrical hydrogen ion concentration or the chloride titration methods. In the case of cementation of the casing if shutting off the water proved successful, the well will produce oil for a while. However, after a shorter or longer period, as a natural production feature, edge water will enter the hale. If the wells are produced at an excessive rate, this natural water encroachment will occur sooner than expected. This will be partly due to the intrusion of edg'e water along an irregular line, partly, if the dome of the reservoir rock is fiat, around the axis of the well base water will rise upward in a cone. If water intrusion occurs unexpectedly, and at the beginning no explanation for its origin can be found', with the aid of the water analysis diagrams the source of the water can soon be found out. It can be ascertained, whether base water or edge water entered the hole, whether it originates from an overlying or underlying perforated zone. Another method of applying water analysis diagrams is as follows: Two oil horizons, for instance.the Lovászi and Rátka sands are opened for simultaneous production, and it has to be ascertained whether both are producing water as well. By means of the chloride titration method it can always be definitely established if the water comes from the Lovászi series. However, it could not be ascertained, whether the Lovászi water is mixed with the U. Rátka water. Namelv — as experienced — the Lovászi water contains 14—26 gr/lit NaCI calculated from chloride. If it is mixed water its presence can undoubtedly be established. With the aid of water analysis diagrarrís it can be ascertained whether Rátka water alsó entered the hole, applying HC03

1. A further application of water diagrams is that they offer explanation regarding the origin of springs and other waters, within the limit of types. Another important feature is that on basis of the composition of the water, régiónál stratigraphical correlation can be made to a certain extent. Within limited areas, for instance within an oil pool this can be made with greater safety. Finally, I would like to mention another interesting application of water diagrams. When an unexpected decline of production is noted in a well, usually the tubing is being pulled to commence testing or a workover iob. In somé instances, for example when puliing the tubing of wells L-22. and L-46., it was noted that the pipes became clogged with water scale. Constituents of the material which caused clogging were as follows: Si02 2.76 % FeaO.-i 2.58 „ CaO 48.05 „ CO2 37.79 „ As indicated by the water diagrams enclosed to my report, the clogging was caused by Rátka water. Both horizons, the Rátka, as well as the Lovászi produced water also. Shutting off the Lovászi sand, the amount of water decreased, .but the possibility of the tubing to become clogged by these constituents still existed. Naturally, scale formation will now require a longer period, because cementing off the Lovászi series a better oilwater ratio has been obtained. Consequently, if the tubing or perforations have become clogged by scale, the possibility is offered to attribute it to the water from one of the sands, and in order to prevent it the water producing horizon should be cemented off immediately upon the intrusion of water. >< HYDROLOGICAL PROBLEMS OF THE GREAT HUNGÁRIÁN PLAIN IN THE LIGHT OF OIL-EXPLORATORY DRILLINGS. By G. SZUROVY, D. Sc. (Hungárián text with figs. on p. 17.] D. C. 551.49(439.14) : 622.322/3 Stratigraphically 3 types of water are to be distinguished in the Great Hungárián Plain: 1. Waters of the mostly sandy formations overlying the beds with Valenciennius-fossiJs marlaceous clays (Holocene, Pleistocene, Levantian, Upper Pannonian and upper of the Lower Pannonian). The first type of water is fresh, being mixed with surface waters. Its temperature corresponds to the geothermic gradient. 2. The waters of the second type are already more salty but their temperature corresponds also to the geothermic gradient. 3. The last named water differs from the first two by its relatíve high salt content. Its temperature can be essentially changed by the infiltration of hot waters through fractures of the faulted bed rocks. The places where hot waters are near to the surtace the geothermic gradient is exceedingly low, on other places where the bed rock lies very deep (9500—11300 ft) the gradient is much higher than normál. The concentration of the salt water is relatively small but it is near to the limits established for waters of oilfields by KREJCI GRAF. The salt water-bearing bottom formátion contains important wet gas- and insignificant oil accumulations as well. >< PETROGRAPHICAL ANALYSIS OF SOMÉ HUNGÁRIÁN THERMAL SPRINGS. By K. LINDNER. (Hungárián text with figs. on p. 25.) D. C. 553.7 : 552.067 In July 1941 I made petrographical researches on muds of the Török-Spring of Rudas-Bath, further of the Szent Antal-, Szent János-, Török-, Zug-, Mária- and Nádor-Springs of Császár-Bath. The mud of Török-Spring's bath contains many fragments of dolomité. On this account it has a light yellowish gray colour. I made my microscopical researches on the sieved part of the mud of diameter 0.3—2.5 mm. In this I discovered a great number of shiny and colorless transparent crystals of baryte. (About 75 kg of BaSOí is flowing through this spring during one year.) Being the temperature of the spring about 42° C, part of CaCOs crystallized in the form of a r a g o n i t e. Besides that, there are opaque metallic grains, of pyrite and I i m o n i t e. Their diameter is about 0.4 mm. Grain analysis sample taken on 1-st July 1941 (Fig. 1). The mud of Szent-Antal-Spring of Császár-Bath has a bluish gray colour and it consists mostly of small grains. Part of CaCOa has crystallized in the form of a r ag o n i t e in this case, too. Occasionally there are somé crystals of baryte and pyrite, which are often found grown on quartz. Besides that the more important minerals are: quartz originating from Danube