Altering Natural Gas Composition In-situ During Production

Abstract

Methods and systems for producing gas from a subsurface formation through a production well and/or sequestering gas in the subsurface formation through an injection well can include monitoring pressure, temperature, and composition of fluids in the subsurface formation using sensors installed downhole in an injection well. The pressure, the temperature, and the composition of fluids in the subsurface formation can be monitored using sensors installed downhole in the production well(s) and/or observation well(s). This approach can predict a volume of gas injection through required to alter the composition of fluids in the subsurface formation to provide a specific fluid composition in the production well. It can also include injecting the predicted volume of gas through the injection well using pumps associated with the injection well as well as, in some cases, producing the fluids in the subsurface formation to surface.

What is claimed is: 
     
         1 . A method of producing gas from a subsurface formation through a production well, the method comprising:
 monitoring pressure, temperature, and composition of fluids in the subsurface formation using sensors installed downhole in an injection well;   monitoring the pressure, the temperature, and the composition of fluids in the subsurface formation using sensors installed downhole;   predicting, without use of a simulation model, a volume of gas injection through required to alter the composition of fluids in the subsurface formation to provide a specific fluid composition in the production well;   injecting the predicted volume of gas through the injection well using pumps associated with the injection well; and   producing the fluids in the subsurface formation to surface through a production well.   
     
     
         2 . The method of  claim 1 , wherein monitoring the pressure, the temperature, and the composition of fluids in the subsurface formation using the sensors installed downhole comprises continuously monitoring the pressure, the temperature, and the composition of fluids in the subsurface formation using the sensors installed downhole in the production well. 
     
     
         3 . The method of  claim 1 , further comprising identifying a target reservoir in which gas injection improves quality of gas produced through the production well. 
     
     
         4 . The method of  claim 3 , wherein the target reservoir has hydrogen sulfide (H 2 S) concentrations above 10%. 
     
     
         5 . The method of  claim 1 , wherein predicting the volume of gas injection comprises training a machine learning model using the pressure, the temperature, and the composition of fluids in the subsurface formation using sensors installed downhole in an injection well and installed downhole in the production well. 
     
     
         6 . The method of  claim 5 , wherein predicting the volume of gas injection using the machine learning model is more computationally efficient than using a simulation model. 
     
     
         7 . The method of  claim 5 , wherein the injection well is one of a plurality of injection wells and monitoring the pressure, the temperature, and the composition of fluids in the subsurface formation comprises monitoring using sensors installed downhole in the plurality of injection wells. 
     
     
         8 . The method of  claim 7 , wherein the production well is one of a plurality of production wells and monitoring the pressure, the temperature, and the composition of fluids in the subsurface formation comprises monitoring using sensors installed downhole in the plurality of production wells. 
     
     
         9 . The method of  claim 7 , wherein monitoring the pressure, the temperature, and the composition of fluids in the subsurface formation comprises monitoring using sensors installed downhole in a plurality of observation wells. 
     
     
         10 . The method of  claim 5 , wherein injecting the predicted volume of gas through the injection well using the pumps associated with the injection well comprises continuously monitor the composition of the fluids and adjusting injection volume and frequency based on the machine learning model. 
     
     
         11 . The method of  claim 5 , wherein injecting the predicted volume of gas through the injection well comprises injecting carbon dioxide (CO 2 ) through the injection well. 
     
     
         12 . The method of  claim 1 , wherein the sensors are installed downhole in the production well. 
     
     
         13 . The method of  claim 1 , wherein the sensors are installed downhole in one or more observation wells. 
     
     
         14 . A method of sequestering gas in a subsurface formation through an injection well, the method comprising:
 monitoring pressure, temperature, and composition of fluids in the subsurface formation using sensors installed downhole in an injection well;   monitoring the pressure, the temperature, and the composition of fluids in the subsurface formation using sensors installed downhole in an observation well   predicting, without use of a simulation model, a volume of gas injection that can be absorbed by fluids in the subsurface formation; and   injecting the predicted volume of gas through the injection well using pumps associated with the injection well.   
     
     
         15 . The method of  claim 14 , wherein monitoring the pressure, the temperature, and the composition of fluids in the subsurface formation using the sensors installed downhole comprises continuously monitoring the pressure, the temperature, and the composition of fluids in the subsurface formation using the sensors installed downhole in the observation well. 
     
     
         16 . The method of  claim 14 , wherein predicting the volume of gas injection comprises training a machine learning model using the pressure, the temperature, and the composition of fluids in the subsurface formation using sensors installed downhole in an injection well and installed downhole in the observation well. 
     
     
         17 . The method of  claim 16 , wherein the injection well is one of a plurality of injection wells and monitoring the pressure, the temperature, and the composition of fluids in the subsurface formation comprises monitoring using sensors installed downhole in the plurality of injection wells. 
     
     
         18 . The method of  claim 17 , wherein the observation well is one of a plurality of observation wells and monitoring the pressure, the temperature, and the composition of fluids in the subsurface formation comprises monitoring using sensors installed downhole in the plurality of observation wells. 
     
     
         19 . The method of  claim 16 , wherein injecting the predicted volume of gas through the injection well comprises injecting carbon dioxide (CO 2 ) through the injection well.