Hidrológiai Közlöny 1942 (22. évfolyam)

Szakosztályi ügyek

Part played by water in Oil production 471 production possible several things must ensue. In the course of sedimentation oil and water will be squeezed out from the compact formation and they will flow towards porous ones. (Some writers contributing in this connexion cherish the supposition that flowing occurs also vertically upon the formations.) Gas, oil, and water find their respective place in the course of flowing thru porous formations more or less according to their specific gravities. This process is called primary migration. Should later on, as the result of some geological effect, the equilibrium prevailing within the formation cease, another migration of oil, water, and gas sets in and continues as long as some equilibrium will not ensue. This phenomenon is called secondary migration. As soon as this will have come to a termination water will have no other part to perform until the production of oil be commenced. In case of deeper drilling the formation shall be opened up and gas, oil, water, or any of them in any combination can be produced. At most points when penetrating thru the formations the bit works from the very beginning also thru such as were wet by water. Ground water is encountered topmost, then comes fresh water, and the deeper penetration will happen water will be more and more salt. Hardly any salt water shall be come across in more than one place, while at other points from the very beginning salt water-bearing formations shall be penetrated by the bit. Such water can be retained within the formation together with oil and gas by means of mud having proper specific gravity. As soon as the hole is drilled casing will be run in the oiland gas-bearing formations as well as those above and below, these shall be cemented off so as to exclude intercommunication. It has been more than once the case that water having been improperly shut off, oil or gas production has been very much in jeopardy and difficulties have had to be overcome to safeguard against water. Upon having successfully shut off water and having oil production started, either temporarily or permanently pure crude shall be produced by the well. During the production of crude oil only it has also been experienced that from time to time the well produced a negligible quantity of water as well. It appears, therefore, that oil and gas somehow manage to carry along towards the hole a portion of the connate water, it collects at the bottom of the hole and begins to surface as soon as it reaches the tubing. As, however, negligible quantities do easily come above ground a considerable length of time shall have to elapse until another batch shall gather. Should a hole penetrate an oil-bearing formation in such a manner that it passes thru not only oil but water as well, production is