Abstract: When production testing a permeable first formation, fluid flowing out from the first formation is subjected to a pressure measurement and a flow rate control. In order to avoid bringing up the fluid flowing out during the production test to a surface position, where the fluid's inherent explosion and fire risk as well as poisonousness could cause substantial problems, a fluid flow path is arranged for fluid transfer only between the first and second formations. The fluid flow path which, in a suitable apparatus, is constituted by a channel-forming pipe. From this channel, the second permeable formation receives the fluid and keeps it for some time. In the position of use, the apparatus is assigned sealing devices such as annulus packers, which are placed such that fluid flow between the formations is limited to only follow the fluid flow path.

Abstract: The invention relates to a method of injecting water and gas, possibly just water, into a petroleum-carrying stratum of a subsoil formation, whereby the water and the gas, possibly just the water, are/is injected by means of an injection well formed in the subsoil formation. The object of the invention is to avoid that water which is to be injected, will require treatment by, among other things, the addition of chemicals inhibiting formation of hydrate from the gas, biological activity in the formation, precipitation of salts and minerals from the water, corrosion of equipment etc. This is realised by the water to be injected, being taken from aquifers in the subsoil formation and carried directly into the injection well through at least one opening which is formed in the wall of the well by said aquifers. Then the water is fed from said opening to the point in the injection well where the water and the gas, possibly just the water, are/is to be injected into said petroleum-carrying stratum.