Method of injecting water and gas

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. The injection well comprises necessary pumping equipment to be used during the injection.

1 . A method of increasing an amount of extractable petroleum comprising: 
 injecting water into a petroleum-carrying stratum of a subsoil formation, whereby the water is injected by means of an injection well formed in the subsoil formation and extending to said petroleum-carrying stratum and wherein that the water to be injected is recovered from an aquifer of the subsoil formation, that the water is carried directly into the injection well through at least one opening formed in the wall of the well by said aquifer, and that the water is fed from said opening to the position in the injection well where the water is to be injected into said petroleum-carrying stratum.    
     
     
         2 . A method according to    claim 1    wherein water and gas are injected into the petroleum-carrying stratum.  
     
     
         3 . A method according to    claim 2    wherein the water and gas are injected simultaneously.  
     
     
         4 . A method according to    claim 2    wherein the water and gas are injected alternatively.  
     
     
         5 . A method according to    claim 1   , wherein the water is recovered from the aquifer located above said petroleum-carrying stratum.  
     
     
         6 . A method according to    claim 1   , wherein the water is recovered from the aquifer located below said petroleum-carrying stratum.  
     
     
         7 . A method according to    claim 5    wherein the injection well is extended to said lower aquifer.  
     
     
         8 . A method according to    claim 6    wherein the injection well is extended to said lower aquifer.  
     
     
         9 . A method according to    claim 1   , wherein the water is pumped from said opening to the position in the injection well where the water is to be injected into said petroleum-carrying stratum.  
     
     
         10 . A method according to    claim 9   , wherein the water is pumped by means of at least one pump positioned in the injection well near said opening in the wall of the well.  
     
     
         11 . A method according to    claim 2   , wherein the gas is supplied at the upper end of the injection well.  
     
     
         12 . A method according to    claim 9   , wherein the water and the gas are supplied simultaneously, possibly alternately, into said petroleum-carrying stratum.  
     
     
         13 . A method according to    claim 1    wherein the water is prevented from entering the aquifer or flowing to the surface, by the provision of at least one check valve between the aquifer and the entrance of an injection pipe provided in the injection well and at least one check valve in the injection pipe, said check valve being provided downstream of a packer in the annulus between the injection pipe and the wall of the well.  
     
     
         14 . A method according to    claim 2    wherein the water and gas are prevented from entering the aquifer or flowing to the surface, by the provision of at least one check valve between the aquifer and the entrance of an injection pipe provided in the injection well and at least one check valve in the injection pipe, said check valve being provided downstream of a packer in the annulus between the injection pipe and the wall of the well.