# US 2017/0254792 A1 · Fluid Composition and Reservoir Analysis Using Gas Chromatography > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0254792 A1 - Document ID: US20170254792A1 - Status: Published application - Kind: A1 - Application number: 15/599,515 - Filed: 2017-05-19 - Published: 2017-09-07 - Earliest claimed: 2014-12-17 - Assignees: Schlumberger Technology Corporation - Applicants: Schlumberger Technology Corporation - Inventors: Adriaan Gisolf; Youxiang Zuo; Ronald E. G. van Hal; Jeffrey Crank - Web page: https://patentgrep.com/patent/US20170254792A1 ## CPC - G01N 33/2823: {Raw oil, drilling fluid or polyphasic mixtures} - E21B 49/087: {Well testing, e.g. testing for reservoir productivity or formation parameters} - E21B 49/10: using side-wall fluid samplers or testers - G01N 30/88: Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86 - G01N 33/28: Oils {, i.e. hydrocarbon liquids} (edible oils or edible fats G01N33/03) - E21B 49/0875: {determining specific fluid parameters} - G01N 2030/8854: {involving hydrocarbons} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract Methods are provided for reservoir analysis. In some embodiments, a reservoir may be analyzed by obtaining abundance ratios at a first measurement station and a second measurement station and determining an abundance ratio trend. Abundance ratios at a third measurement station may be obtained and plotted versus depth with the previously obtained abundance ratios. A change in the abundance ratio trend may be identified and result in further investigation of the reservoir. If the abundance ratio is unchanged, additional abundance ratios may be obtained and plotted versus depth to further evaluate the abundance ratio trend. Methods for reservoir analysis using fluid predictions with and without offset well information are also provided. ## Claims ### Claim 1 A method for analyzing a reservoir traversed by a wellbore, comprising: obtaining, from a first measurement station within the wellbore, a first composition of a first fluid sample acquired at the first measurement station; determining an Equation of State (EoS) model for a reservoir fluid using the first composition; obtaining, from a second measurement station within the wellbore, a second composition of a second fluid sample acquired at the second measurement station; tuning the EoS model using the second composition; generating a predicted fluid profile using the EoS model; obtaining, from a third measurement station within the wellbore, a component ratio from a gas chromatogram of a third fluid sample acquired at the third measurement station; comparing the component ratio to the predicted fluid profile; using the comparison to analyze the reservoir. ### Claim 2 (depends on 1) The method of claim 1, wherein the predicted fluid profile comprises hydrocarbon fraction ratios of the fluid as a function of depth. ### Claim 3 (depends on 1) The method of claim 1, wherein the component ratio comprises a hydrocarbon fraction ratio. ### Claim 4 (depends on 3) The method of claim 3, wherein the hydrocarbon fraction ratio comprises hydrocarbon fractions C1 through C8. ### Claim 5 (depends on 1) The method of claim 1, wherein using the comparison to analyze the reservoir comprises determining whether a fluid column is in equilibrium. ### Claim 6 (depends on 1) The method of claim 1, wherein obtaining, from a first measurement station within the wellbore, a first composition of a first fluid sample acquired at the first measurement station comprises: obtaining optical absorption measurements of the first fluid sample; obtaining a gas chromatogram of the first fluid sample; and determining the first composition from the optical absorption measurements and the gas chromatogram. ### Claim 7 (depends on 1) The method of claim 1, wherein obtaining, from a second measurement station within the wellbore, a second composition of a second fluid sample acquired at the second measurement station comprises: obtaining optical absorption measurements of the second fluid sample; obtaining a gas chromatogram of the second fluid sample; and determining the second composition from the optical absorption measurements and the gas chromatogram. ### Claim 8 A method for analyzing a reservoir traversed by a wellbore, comprising: obtaining, from at least one offset well, a fluid composition; determining an Equation of State (EoS) model for a reservoir fluid using the fluid composition from the offset well; obtaining, from a measurement station within the wellbore, a component ratio from a gas chromatogram of a fluid sample acquired at the station; comparing the component ratio to the predicted fluid profile; and using the comparison to analyze the reservoir. ### Claim 9 (depends on 8) The method of claim 8, wherein the predicted fluid profile comprises hydrocarbon fraction ratios of the fluid as a function of depth. ### Claim 10 (depends on 8) The method of claim 8, wherein the component ratio comprises a hydrocarbon fraction ratio. ### Claim 11 (depends on 10) The method of claim 10, wherein the hydrocarbon fraction ratio comprises hydrocarbon fractions C1 through C8. ### Claim 12 (depends on 10) The method of claim 10, wherein using the comparison to analyze the reservoir comprises determining whether a fluid column is in equilibrium. ### Claim 13 (depends on 10) The method of claim 10, wherein obtaining, from at least one offset well, a fluid composition comprises obtaining a fluid composition from laboratory analysis of a fluid sample. ### Claim 14 (depends on 10) The method of claim 10, wherein using the comparison to analyze the reservoir comprises determining whether a fluid column is in equilibrium.