Hidrológiai Közlöny 1942 (22. évfolyam)

Szakosztályi ügyek

474 János Dinda some time be normal but by lapse of time more and more salt will fall out around the well and same will fill up the pores of the formation. The pores being plugged water flooding will more and more be retarded, resistance will increase and finally the pressure shall prove inadequate to keep the water in movement. In order to prevent salt in such water from falling out, at many wells it is being softened just previous to injection. As has been set forth above the salt content of formation water varies from that of fresh water to that of sea water or even exceeds same. In the course of migration water solve to the point of saturation the salts of all those formations as it passes through. Often a quite logical connection can be established between salt content and geological age, respectively, location. Within Hungary in the Budafapuszta Field the salt content of the formations underlying one another is as follows: 1.3, 1.7, 1.8—2.6 gram/litre, while in the Lovászi Field it varies between 1—2, 8—28 gram/litre. The lower salt content is characteristic of the upper, geologically younger formations, while the higher one refers to the lower, geologically older formations. Different waters might bring about corrosion. It is usually the result of electrochemical effect brought about by chemicals solved in crude, gas,, and water. Salt or acid-bearing waters do on one part corrode actively, or, on the other hand speed up corrosion. Alkali waters generally speaking do not corrode. C0

2 and H

2S when solved in water do cause corrosion. As water has a harmful influence upon the production of oil it should be shut out. Mention has already been made of its initial shutting off, namely, after the completion of drilling and running in casing the space between the wall of the hole and the casing is being filled with cement slurry in such a manner as will render communication of waters in the various formations above and below the producing zone impossible. However, in case water has not been shut off completely in the beginning, later it might appear to cause difficulties. (For instance water might penetrate from the bottom of the basin,, or from the sides, or cement behind the cemented casing might leak etc.) Various methods are being resorted to in cementing out water. However, there are times when no method affords proper solution and in such instance chiefly chemical means are being availed of, tho with more or less success. Such chemicals are: sodium silicate, sodium carbonate solved in water, antimonchloride solved in oil, silicium tetrachloride, various soap and colloidal solutions. All these are applied with a view of having the pores of the formations filled up. Such