Measuring Gas in Shale Reservoirs

Abstract

Methods for determining a volume of stored gas within a rock sample includes loading a rock sample into an overburden cell. A hydrocarbon gas at a gas pressure is applied to the rock sample and a confining fluid at a confining pressure is applied to the overburden cell. The confining pressure and the gas pressure are increased until a first pressure and temperature condition is met. With the rock sample maintained at the first temperature and pressure condition, a nuclear magnetic resonance spectrometer is used to scan the rock sample and measure a hydrocarbon gas volume within the rock sample. This measured hydrocarbon gas volume is then corrected using a Real Gas Index to determine the volume of stored gas within the rock sample.

1 - 20 . (canceled) 
     
     
         21 . A system for testing a rock sample comprising:
 an overburden system adapted to contain a rock sample;   a gas injection system coupled to the overburden cell and configured to inject pressurized gas into the rock sample; and   a nuclear magnetic resonance spectrometer operable to measure the amount of pressurized gas contained in the rock sample.   
     
     
         22 . The system of  claim 21 , wherein the overburden system further comprises:
 an overburden cell adapted to contain a rock sample; and   a fluid pump adapted to apply a confining pressure to the overburden cell.   
     
     
         23 . The system of  claim 22 , wherein the overburden system further comprises a heater that heats the overburden cell. 
     
     
         24 . The system of  claim 22 , wherein the overburden cell is ceramic. 
     
     
         25 . The system of  claim 22 , wherein the fluid pump applies the confining pressure with a confining fluid. 
     
     
         26 . The system of  claim 25 , wherein the overburden system further comprises a heater that heats the confining fluid. 
     
     
         27 . The system of  claim 21 , wherein the gas injection system further comprises:
 an injection pump adapted to supply a gas to the rock sample; and   a supply of gas coupled to the injection pump.   
     
     
         28 . The system of  claim 27 , wherein the injection pump is a vacuum pump. 
     
     
         29 . The system of  claim 27 , wherein the supply of gas contains a hydrocarbon gas.