Graphical method for assisting multi-zones commingling decision

Abstract

A method and a system determine multi-zones commingling in oil field production. The system includes a processing circuitry configured to: identify a plurality of zones in a well to be analyzed based on first differences in properties or flow performance; calculate a normalized bubble point pressure; define a first bottom hole flowing pressure for the well; define flowing pressures after excluding the zone with the highest saturation pressure; calculate a normalized bottom-hole flowing pressure and a corresponding flow rate ratio; plot the flow rate ratio versus the normalized bottom-hole flowing pressure and the flow rate ratio versus the bottom-hole flowing pressure in a Cartesian scale; and determine the feasibility to produce from all the zones.

1 . A method for determining multi-zones commingling in oil field production comprising:
 identifying a plurality of zones in a well to be analyzed based on first differences in properties or flow performance;   calculating a normalized bubble point pressure for the zones;   defining a first bottom hole flowing pressure for the well;   defining flowing pressures for each zone after excluding the zone with the highest saturation pressure;   calculating a normalized bottom-hole flowing pressure and a corresponding flow rate ratio for the well;   correlating the flow rate ratio versus the normalized bottom-hole flowing pressure and the flow rate ratio versus the bottom-hole flowing pressure in a Cartesian scale;   determining a feasibility to produce from all of the zones based on saturation pressures of each zone, a relative location of a zone with a highest saturation pressure to the rest of the zones, a relative depth of the s zone with the highest saturation pressure to the rest of the zones, a relative productivity index of the zone with the highest saturation pressure to the rest of the zones.   
     
     
         2 . The method of  claim 1 , wherein the normalized bubble point pressure is a first ratio between a second difference in bubble point pressures between two zones that have a highest and a second highest value, to the bubble point pressure for the zone with the highest value. 
     
     
         3 . The method of  claim 2 , wherein the bubble point pressure is the pressure below which a two-phase fluid appears in a reservoir or a wellbore. 
     
     
         4 . The method of  claim 3 , wherein the two-phase fluid is gas and liquid. 
     
     
         5 . The method of  claim 1 , wherein the normalized bottom-hole flowing pressure is a second ratio of a third difference between a second bottom hole flowing pressure if all zones are considered and a third bottom hole flowing pressure if the zone that has the highest saturation pressure value is excluded; to the second bottom hole flowing pressure if all zones are considered. 
     
     
         6 . The system of  claim 1 , wherein the flow rate ratio is a third ratio between a first expected flow rate from all zones to a second expected flow rate if that zone with the highest saturation pressure is excluded. 
     
     
         7 . The method of  claim 1 , wherein a possibility of commingling all zones is higher when the saturation pressure of the zone with the highest saturation pressure is closer to the saturation pressure of the rest of the zones. 
     
     
         8 . The method of  claim 1 , wherein the possibility of commingling all zones is higher when the zone with the highest saturation pressure is deeper than the rest of the zones. 
     
     
         9 . The method of  claim 1 , wherein the possibility of commingling all zones is higher when the productivity index of the zone with the highest saturation pressure is greater than the productivity index of the rest of the zones. 
     
     
         10 . A system for determining multi-zones commingling in oil field production comprising:
 processing circuitry configured to:   identify a plurality of zones in a well to be analyzed based on first differences in properties or flow performance;   calculate a normalized bubble point pressure;   define a first bottom hole flowing pressure for the well;   define flowing pressures after excluding the zone with the highest saturation pressure;   calculate a normalized bottom-hole flowing pressure and a corresponding flow rate ratio;   compute the Flow Rate Ratio versus the normalized bottom-hole flowing pressure and the flow rate ratio versus the bottom-hole flowing pressure in a Cartesian scale; and   determine a feasibility to produce from all the zones based on saturation pressures of each zone, a relative location of a zone with a highest saturation pressure to the rest of the zones, a relative depth of the s zone with the highest saturation pressure to the rest of the zones, a relative productivity index of the zone with the highest saturation pressure to the rest of the zones.   
     
     
         11 . The system of  claim 10 , wherein the normalized bubble point pressure is a first ratio between a second difference in bubble point pressures between two zones that have a highest and a second highest value; to the bubble point pressure for the zone with the highest value. 
     
     
         12 . The system of  claim 11 , wherein the bubble point pressure is the pressure below which a two-phase fluid appears in a reservoir or a wellbore. 
     
     
         13 . The system of  claim 12 , wherein the two-phase fluid is gas and liquid. 
     
     
         14 . The system of  claim 10 , wherein the normalized bottom-hole flowing pressure is a second ratio of a third difference between a second bottom hole flowing pressure if all zones are considered and a third bottom hole flowing pressure if the zone that has the highest saturation pressure value is excluded; to the second bottom hole flowing pressure if all zones are considered. 
     
     
         15 . The system of  claim 10 , wherein the flow rate ratio is a third ratio between a first expected flow rate from all zones to a second expected flow rate if that zone with the highest saturation pressure is excluded. 
     
     
         16 . The system of  claim 10 , wherein a possibility of commingling all zones is higher when the saturation pressure of the zone with the highest saturation pressure is closer to the saturation pressure of the rest of the zones. 
     
     
         17 . The system of  claim 10 , wherein the possibility of commingling all zones is higher when the zone with the highest saturation pressure is deeper than the rest of the zones. 
     
     
         18 . The system of  claim 10 , wherein the possibility of commingling all zones is higher when the productivity index of the zone with the highest saturation pressure is greater than the productivity index of the rest of the zones. 
     
     
         19 . A non-transitory computer-readable medium including executable instructions, which when executed by a computer processor, cause the computer processor to execute a method comprising:
 identifying a plurality of zones in a well to be analyzed based on first differences in properties or flow performance;   calculating a normalized bubble point pressure;   defining a first bottom hole flowing pressure for the well;   defining flowing pressures after excluding the zone with the highest saturation pressure;   calculating a normalized bottom-hole flowing pressure and a corresponding flow rate ratio;   computing the flow rate ratio versus the normalized bottom-hole flowing pressure and the flow rate ratio versus the bottom-hole flowing pressure in a Cartesian scale; and   determining a feasibility to produce from all the zones based on saturation pressures of each zone, a relative location of a zone with a highest saturation pressure to the rest of the zones, a relative depth of the s zone with the highest saturation pressure to the rest of the zones, a relative productivity index of the zone with the highest saturation pressure to the rest of the zones.