# US 9,518,461 B2 · System and method for a pressure test > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,518,461 B2 - Document ID: US9518461B2 - Status: Granted - Kind: B2 - Application number: 14/604,379 - Filed: 2015-01-23 - Published: 2015-05-14 - Granted: 2016-12-13 - Earliest claimed: 2013-10-17 - Assignees: Innovative Pressure Testing, LLC - Applicants: Innovative Pressure Testing, LLC - Inventors: Charles M. Franklin; Richard A. Cully - Web page: https://patentgrep.com/patent/US9518461B2 ## CPC - E21B 47/06: Measuring temperature or pressure - E21B 47/117: Detecting leaks, e.g. from tubing, by pressure testing - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract A method for determining integrity of a wellbore. The method includes underbalancing a volume of fluid in the wellbore, receiving pressure data of the wellbore after shut-in of the wellbore, determining a pressure curvature based on the pressure data, and generating a failing indication as a result of the pressure curvature indicating that the slope is constant or increasing in absolute value. The failing indication indicates fluid communication across a wellbore boundary. ## Claims ### Claim 1 A method for determining integrity of a wellbore, the method comprising: underbalancing a volume of fluid in the wellbore; receiving, by a processor, pressure data of the wellbore after shut-in of the wellbore; determining, by the processor, a pressure curvature based on the pressure data; and generating a failing indication as a result of the pressure curvature indicating that an absolute value of a slope of the pressure data is constant or increasing; wherein the failing indication indicates fluid communication across a wellbore boundary. ### Claim 2 (depends on 1) The method of claim 1 wherein underbalancing further comprises: replacing at least a portion of a volume of fluid in the wellbore with a lighter-weight fluid; and shutting in the wellbore. ### Claim 3 (depends on 1) The method of claim 1 further comprising, after generating a failing indication, applying a curve-fitting algorithm to the pressure data to generate a mathematical form that represents the pressure data. ### Claim 4 (depends on 1) The method of claim 1 further comprising: entering a passing state in response to the pressure curvature indicating that the slope is decreasing; exiting the passing state in response to the pressure curvature indicating that the slope is constant or increasing; and generating a passing indication as a result of remaining in the passing state for at least a predetermined time period. ### Claim 5 (depends on 4) The method of claim 4 wherein the passing indication indicates that a formation fluid is not interacting with the volume of fluid in the wellbore when the wellbore is in the underbalanced condition. ### Claim 6 (depends on 1) The method of claim 1 further comprising generating the failing indication as a result of the pressure or slope having falling outside a predetermined range. ### Claim 7 A system for determining integrity of a wellbore, the system comprising: at least one pressure sensor coupled to a volume of fluid in the wellbore; and a processor coupled to the pressure sensor, the processor configured to: receive pressure data of the wellbore from the at least one pressure sensor after shut-in of the wellbore in an underbalanced condition; determine a pressure curvature based on the pressure data; and generate a failing indication as a result of the pressure curvature indicating that an absolute value of a slope of the pressure data is constant or increasing; wherein the failing indication indicates fluid communication across a wellbore boundary. ### Claim 8 (depends on 7) The system of claim 7 further comprising: a pump configured to circulate a lighter-weight fluid into the wellbore to create the underbalanced condition; and a valve to shut in the wellbore. ### Claim 9 (depends on 7) The system of claim 7 wherein the processor is further configured to apply a curve-fitting algorithm to the pressure data to generate a mathematical form that represents the pressure data. ### Claim 10 (depends on 7) The system of claim 7 wherein the processor is further configured to: enter a passing state in response to the pressure curvature indicating that the slope is decreasing; exit the passing state in response to the pressure curvature indicating that the slope is constant or increasing; and generate a passing indication as a result of remaining in the passing state for at least a predetermined time period. ### Claim 11 (depends on 10) The system of claim 10 wherein the passing indication indicates that a formation fluid is not interacting with the volume of fluid in the wellbore when the wellbore is in the underbalanced condition. ### Claim 12 (depends on 7) The system of claim 7 wherein the processor is further configured to generate the failing indication as a result of the pressure or slope having a value outside a predetermined range. ### Claim 13 A non-transitory computer-readable medium containing instructions that, when executed by a processor, cause the processor to: receive pressure data of a wellbore from a pressure sensor coupled to a volume of fluid in the wellbore after shut-in of the wellbore, caused by a valve, in an underbalanced condition caused by a pump circulating a lighter-weight fluid into the well bore to create the underbalanced condition; determine a pressure curvature based on the pressure data; and generate a failing indication as a result of the pressure curvature indicating that an absolute value of a slope of the pressure data is constant or increasing; wherein the failing indication indicates fluid communication across a wellbore boundary. ### Claim 14 (depends on 13) The non-transitory computer-readable medium of claim 13 wherein the instructions, when executed, further cause the processor to apply a curve-fitting algorithm to the pressure data to generate a mathematical form that represents the pressure data. ### Claim 15 (depends on 13) The non-transitory computer-readable medium of claim 13 wherein the instructions, when executed, further cause the processor to: enter a passing state in response to the pressure curvature indicating that the slope is decreasing; exit the passing state in response to the pressure curvature indicating that the slope is constant or increasing; and generate a passing indication as a result of remaining in the passing state for at least a predetermined time period. ### Claim 16 (depends on 15) The non-transitory computer-readable medium of claim 15 wherein the passing indication indicates that a formation fluid is not interacting with the volume of fluid in the wellbore when the wellbore is in the underbalanced condition. ### Claim 17 The non-transitory computer-readable medium 13 wherein the instructions, when executed, further cause the processor to generate the failing indication as a result of the pressure slope having a value falling outside a predetermined range. ### Claim 18 (depends on 1) The method of claim 1 further comprising generating the failing indication as a result of the pressure curvature indicating that the absolute value of eh slope of the pressure data is constant and greater than a predetermined threshold. ### Claim 19 (depends on 7) The method of claim 7 wherein the processor is further configured to generate the failing indication as a result of the pressure curvature indicating that the absolute value of the slope of the pressure data is constant and greater than a predetermined threshold. ### Claim 20 (depends on 13) The non-transitory computer-readable medium of claim 13 wherein the instructions, when executed, further cause the processor to generate the failing indication as a result of the pressure curvature indicating that the absolute value of the slope of the pressure data is constant and greater than a predetermined threshold.