Methods and systems for recovering oil from subterranean reservoirs

A system for recovering oil from a subterranean reservoir, the system comprising:

• an injection flow path for delivering injection gas into a plurality of regions of a subterranean reservoir;
• wherein the injection flow path comprises a plurality of outflow devices arranged along the injection flow path;
• wherein a first one of the plurality of outflow devices, located in a first region of the reservoir, is configured to provide a first pressure drop across the device;
• and a second one of the plurality of outflow devices, located in a second region of the reservoir, is configured to provide a second pressure drop, wherein the first pressure drop and second pressure drop are different in order to suit the subterranean reservoir;
• a production flow path for producing oil from a plurality of regions of the subterranean reservoir;
• wherein the production flow path comprises a plurality of inflow devices arranged along the production flow path;
• wherein at least one of the plurality of inflow devices is configured to choke the flow of the injection gas into the production flow path from the reservoir such that a residence time of the injection gas within the subterranean reservoir is increased.

A method for recovering oil from a subterranean reservoir, the method comprising:

• delivering an injection gas through an injection flow path into a plurality of regions of the subterranean reservoir via a plurality of outflow devices arranged along the injection flow path;
• producing oil from a first region of the reservoir using one or more first inflow devices arranged along the production flow path, the first inflow devices configured to define a first pressure drop across the first inflow device;
• producing oil from a second region of the reservoir using one or more second inflow devices arranged along the production flow path, configured to define a second pressure drop across the second inflow device, arranged along the production flow path, wherein the second pressure drop is different to the first pressure drop, in order to balance production across the subterranean reservoir;
• and
• restricting flow of the injection gas into the production flow path from the reservoir by choking the flow of the injection gas through at least one of the plurality of inflow devices such that a residence time of the injection gas within the reservoir is increased.