Surface transit time determination

Abstract

A system for detecting hydrocarbons in a subterranean formation includes an outlet sensor configured to measure an outlet drilling fluid parameter of a drilling fluid. The system also includes an inlet sensor configured to measure an inlet drilling fluid parameter of the drilling fluid. The system also includes a gas extractor positioned downstream from the outlet of the wellbore and upstream from the inlet sensor. The gas extractor is configured to extract a gas from the drilling fluid. The system also includes a computing system configured to determine a first time when the outlet drilling fluid parameter increases by more than a first threshold, determine a second time when the inlet drilling fluid parameter becomes substantially constant or increases by more than a second threshold, and determine a surface transit time of the drilling fluid based at least partially upon the first time and the second time.

What is claimed is: 
     
         1 . A system for detecting hydrocarbons in a subterranean formation, comprising:
 an outlet sensor positioned downstream from an outlet of a wellbore and upstream from or at least partially within a shaker, wherein the outlet sensor is configured to measure an outlet drilling fluid parameter of a drilling fluid;   an inlet sensor positioned downstream from the outlet sensor and upstream from an inlet of the wellbore, wherein the inlet sensor is configured to measure an inlet drilling fluid parameter of the drilling fluid;   a gas extractor positioned downstream from the outlet of the wellbore and upstream from the inlet sensor, wherein the gas extractor is configured to extract a gas from the drilling fluid; and   a computing system configured to perform operations, wherein the operations comprise:
 determining a first time when the outlet drilling fluid parameter increases by more than a first threshold; 
 determining a second time when the inlet drilling fluid parameter becomes substantially constant or increases by more than a second threshold; and 
 determining a surface transit time of the drilling fluid based at least partially upon the first time and the second time. 
   
     
     
         2 . The system of  claim 1 , wherein the outlet drilling fluid parameter comprises a level or a flow rate of the drilling fluid, and wherein the inlet drilling fluid parameter comprises the level or the flow rate. 
     
     
         3 . The system of  claim 1 , wherein the outlet sensor comprises a flow paddle configured to measure the flow rate of the drilling fluid through the outlet of the wellbore, through the shaker, or between the outlet of the wellbore and the shaker. 
     
     
         4 . The system of  claim 1 , wherein the outlet sensor is positioned in a header box of the shaker, and wherein the shaker is positioned downstream from the outlet of the wellbore and upstream from the inlet sensor. 
     
     
         5 . The system of  claim 1 , wherein the system does not comprise a second gas extractor. 
     
     
         6 . The system of  claim 1 , wherein the system does not comprise a second gas extractor positioned in a suction tank, at the inlet of the wellbore, or between the suction tank and the inlet of the wellbore. 
     
     
         7 . The system of  claim 1 , wherein the operations further comprise determining an outlet hydrocarbon contribution in the drilling fluid based at least partially upon the gas extracted from the drilling fluid. 
     
     
         8 . The system of  claim 7 , wherein the operations further comprise determining an inlet hydrocarbon contribution in the drilling fluid based at least partially upon the surface transit time and the outlet hydrocarbon contribution. 
     
     
         9 . The system of  claim 8 , wherein the operations further comprise determining an actual hydrocarbon contribution in the drilling fluid from the subterranean formation based at least partially upon the outlet hydrocarbon contribution and the inlet hydrocarbon contribution. 
     
     
         10 . The system of  claim 9 , wherein the operations further comprise displaying the outlet drilling fluid parameter, the first time, the inlet drilling fluid parameter, the second time, the surface transit time, the outlet hydrocarbon contribution, the inlet hydrocarbon contribution, the actual hydrocarbon contribution, or a combination thereof. 
     
     
         11 . A non-transitory computer-readable medium storing instructions that, when executed by at least one processor of a computing system, cause the computing system to perform operations, the operations comprising:
 receiving an outlet drilling fluid parameter measured by an outlet sensor, wherein the outlet drilling fluid parameter comprises a level or a flow rate of a drilling fluid, and wherein the outlet sensor is positioned downstream from an outlet of a wellbore;   determining a first time when the outlet drilling fluid parameter increases by more than a predetermined outlet drilling fluid parameter threshold;   receiving an inlet drilling fluid parameter measured by an inlet sensor, wherein the inlet drilling fluid parameter comprises the level or the flow rate, and wherein the inlet sensor is positioned downstream from the outlet sensor and upstream from an inlet of the wellbore;   determining a second time when the inlet drilling fluid parameter becomes substantially constant or increases by more than a predetermined inlet drilling fluid parameter threshold;   determining a surface transit time of the drilling fluid by subtracting the first time from the second time;   determining an outlet hydrocarbon contribution in the drilling fluid based at least partially upon gas extracted from the drilling fluid by a gas extractor, wherein the gas extractor is positioned at the outlet of the wellbore, at a shaker, or between the outlet of the wellbore and the shaker; and   determining an inlet hydrocarbon contribution in the drilling fluid based at least partially upon the surface transit time and the outlet hydrocarbon contribution.   
     
     
         12 . The non-transitory computer-readable medium of  claim 11 , wherein the outlet sensor comprises a flow paddle configured to measure the flow rate of the drilling fluid through the outlet of the wellbore, through the shaker, or between the outlet of the wellbore and the shaker, and wherein the inlet sensor comprises a level sensor configured to measure the level of the drilling fluid in a suction tank, wherein the suction tank is positioned downstream from the shaker and upstream from the inlet of the wellbore. 
     
     
         13 . The non-transitory computer-readable medium of  claim 11 , further comprising determining an actual hydrocarbon contribution in the drilling fluid from a subterranean formation based at least partially upon the outlet hydrocarbon contribution and the inlet hydrocarbon contribution. 
     
     
         14 . The non-transitory computer-readable medium of  claim 13 , further comprising displaying the outlet drilling fluid parameter, the first time, the inlet drilling fluid parameter, the second time, the surface transit time, the outlet hydrocarbon contribution, the inlet hydrocarbon contribution, the actual hydrocarbon contribution, or a combination thereof. 
     
     
         15 . The non-transitory computer-readable medium of  claim 13 , further comprising causing a wellsite action to be performed based at least partially upon the actual hydrocarbon contribution. 
     
     
         16 . A computing system, comprising:
 one or more processors; and   a memory system comprising one or more non-transitory computer-readable media storing instructions that, when executed by at least one of the one or more processors, cause the computing system to perform operations, the operations comprising:
 receiving an outlet drilling fluid parameter measured by an outlet sensor, wherein the outlet drilling fluid parameter comprises a level or a flow rate of a drilling fluid, and wherein the outlet sensor comprises:
 a first level sensor configured to measure the level of the drilling fluid in a shaker, wherein the shaker is positioned downstream from an outlet of a wellbore and upstream from an inlet sensor; or 
 a first flow paddle configured to measure the flow rate of the drilling fluid through the outlet of the wellbore, through the shaker, or between the outlet of the wellbore and the shaker; 
 
 determining a first time when the outlet drilling fluid parameter increases by more than a predetermined outlet drilling fluid parameter threshold; 
 receiving an inlet drilling fluid parameter measured by the inlet sensor, wherein the inlet drilling fluid parameter comprises the level or the flow rate, and wherein the inlet sensor comprises:
 a second level sensor configured to measure the level of the drilling fluid in a suction tank, wherein the suction tank is positioned downstream from the shaker and upstream from an inlet of the wellbore; or 
 a second flow paddle configured to measure the flow rate of the drilling fluid into the suction tank, into the inlet of the wellbore, or between the suction tank and the inlet of the wellbore; 
 
 determining a second time when the inlet drilling fluid parameter becomes substantially constant or increases by more than a predetermined inlet drilling fluid parameter threshold; 
 determining a surface transit time of the drilling fluid by subtracting the first time from the second time; 
 determining an outlet hydrocarbon contribution in the drilling fluid based at least partially upon gas extracted from the drilling fluid by an outlet gas extractor, wherein the outlet gas extractor is positioned at the outlet of the wellbore, at the shaker, or between the outlet of the wellbore and the shaker; 
 determining an inlet hydrocarbon contribution in the drilling fluid based at least partially upon the surface transit time and the outlet hydrocarbon contribution; and 
 determining an actual hydrocarbon contribution in the drilling fluid from a subterranean formation by subtracting the inlet hydrocarbon contribution from the outlet hydrocarbon contribution. 
   
     
     
         17 . The computing system of  claim 16 , wherein the outlet sensor comprises the first flow paddle, and wherein the inlet sensor comprises the second level sensor. 
     
     
         18 . The computing system of  claim 16 , wherein an inlet gas extractor is not functioning or not present. 
     
     
         19 . The computing system of  claim 16 , further comprising displaying the outlet drilling fluid parameter, the first time, the inlet drilling fluid parameter, the second time, the surface transit time, the outlet hydrocarbon contribution, the inlet hydrocarbon contribution, and the actual hydrocarbon contribution. 
     
     
         20 . The computing system of  claim 16 , further comprising generating or transmitting a signal in response to the hydrocarbon contribution in the drilling fluid, wherein the signal causes or instructs a wellsite action to be performed.