# US 11,898,437 B2 · Method and system for determining fluid level change using pressure monitoring of annular gas > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,898,437 B2 - Document ID: US11898437B2 - Status: Granted - Kind: B2 - Application number: 17/555,048 - Filed: 2021-12-17 - Published: 2023-06-22 - Granted: 2024-02-13 - Earliest claimed: 2021-12-17 - Assignees: Saudi Arabian Oil Company - Applicants: Saudi Arabian Oil Company - Inventors: Jianhui Xu; Bodong Li; Guodong Zhan; Chinthaka P. Gooneratne; Timothy Eric Moellendick; Graham Hitchcock - Web page: https://patentgrep.com/patent/US11898437B2 ## CPC - E21B 47/047: Liquid level (measuring depth or liquid level using radioactive markers E21B47/053) - E21B 33/06: Blow-out preventers {, i.e. apparatus closing around a drill pipe, e.g. annular blow-out preventers (rotating blow-out preventers E21B33/085)} - E21B 33/127: with inflatable sleeve (E21B33/122, E21B33/124 take precedence) - E21B 47/06: Measuring temperature or pressure - E21B 47/10: Locating fluid leaks, intrusions or movements - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract A method includes creating a chamber within an annulus between a wellbore casing and a drillpipe. An upper boundary of the chamber includes a seal and a lower boundary of the chamber includes a liquid surface and determining a volume of the chamber at a first time. The method further includes determining the volume of the chamber includes measuring, using a pressure gauge, a first pressure within the chamber, changing an amount of a gas in the chamber, and measuring, using the pressure gauge, a second pressure within the chamber. The method further includes determining a first volume of gas within the chamber based on the first and second pressure measurements and the change in the amount of gas, and determining a first fluid level based on the first volume of the chamber. ## Claims ### Claim 1 A method, comprising: creating a chamber within an annulus between a wellbore casing and a drillpipe, wherein an upper boundary of the chamber comprises a seal and a lower boundary of the chamber comprises a liquid surface; determining a volume of the chamber at a first time, wherein determining the volume of the chamber comprises: measuring, using a pressure gauge, a first pressure within the chamber, changing an amount of a gas in the chamber using a gas pump, measuring, using the pressure gauge, a second pressure within the chamber, determining a first volume of gas within the chamber based on the first and second pressure measurements and the change in the amount of gas, and determining a first fluid level based on the first volume of the chamber. ### Claim 2 (depends on 1) The method of claim 1, further comprising: determining a second volume of the chamber at a second time; determining a second fluid level based on the second volume of the chamber; and determining a fluid loss by calculating a difference between the first fluid level and the second fluid level. ### Claim 3 (depends on 2) The method of claim 2, further comprising: creating a fluid loss control plan based on the fluid loss; and executing the fluid loss control plan. ### Claim 4 (depends on 1) The method of claim 1, wherein the seal comprises an inflatable packer disposed in the annulus. ### Claim 5 (depends on 1) The method of claim 1, wherein the seal comprises a blowout preventer. ### Claim 6 (depends on 5) The method of claim 5, wherein changing an amount of gas in the chamber comprises pumping gas through a manual kill valve on the blowout preventer. ### Claim 7 (depends on 1) The method of claim 1, wherein changing an amount of gas in the chamber comprises: installing a specialized drillpipe; connecting a gas conduit to the specialized drillpipe; and pumping gas through the gas conduit. ### Claim 8 (depends on 7) The method of claim 7, wherein the gas conduit is a flexible gas hose. ### Claim 9 (depends on 7) The method of claim 7, wherein the pressure gauge is disposed on the gas conduit. ### Claim 10 (depends on 1) The method of claim 1, wherein the pressure gauge is disposed on the seal. ### Claim 11 (depends on 1) The method of claim 1, wherein the volume of gas within the chamber is calculated with an ideal gas equation. ### Claim 12 An apparatus, comprising: a casing disposed within a wellbore; a drillpipe disposed within the casing, wherein an annulus is created between the casing and the drillpipe; a seal disposed in the annulus; a chamber, wherein an upper boundary of the chamber comprises the seal and a lower boundary of the chamber comprises a surface of a liquid; a pressure gauge connected to the chamber; a specialized drillpipe section threadably connected to the drillpipe; and a flexible gas hose fluidly connected to the annulus through the specialized drillpipe section. ### Claim 13 (depends on 12) The apparatus of claim 12, wherein a fluid level comprises a distance between the seal and the surface of the fluid. ### Claim 14 (depends on 12) The apparatus of claim 12, wherein the seal comprises an inflatable packer disposed in the annulus. ### Claim 15 (depends on 12) The apparatus of claim 12, wherein the seal comprises a blowout preventer. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein the pressure gauge is installed on a choke line. ### Claim 17 (depends on 15) The apparatus of claim 15, wherein the pressure gauge is a digital and high frequency sampling pressure gauge. ### Claim 18 (depends on 15) The apparatus of claim 15, wherein a kill line is connected from a gas source to the blowout preventer. ### Claim 19 (depends on 12) The apparatus of claim 12, wherein a hard conduit is connected to the drillpipe.