Identifying hydrocarbon sweet spots using carbon dioxide geochemistry

Patent metadata

Field	Value
Publication number	US-11047233-B2
Application number	US-201916553930-A
Country	US
Kind code	B2
Filing date	Aug 28, 2019
Priority date	Aug 28, 2019
Publication date	Jun 29, 2021
Grant date	Jun 29, 2021

Abstract

Embodiments provide a method for evaluating a hydrocarbon-bearing formation. The method includes the step of identifying a hydrocarbon sweet spot. The identifying step includes determining a carbon dioxide content of a gas sample retrieved from the hydrocarbon-bearing formation. The identifying step includes determining an isotopic signature of carbon dioxide of the gas sample. The carbon dioxide content of the gas sample retrieved from the hydrocarbon sweet spot can have a mole percentage ranging from 9 percent to 20 percent. The isotopic signature of carbon dioxide of the gas sample retrieved from the hydrocarbon sweet spot can have a δ 13 C value greater than −10 per mil. The identifying step can further include determining a cutoff range of the carbon dioxide content corresponding to the hydrocarbon sweet spot. The cutoff range can have a mole percentage ranging from 9 percent to 20 percent. The identifying step can further include obtaining a gas flow rate of the hydrocarbon-bearing formation. The gas flow rate can be greater than 10 million standard cubic feet per day.

First claim

What is claimed is:

1. A method for evaluating a hydrocarbon-bearing formation, the method comprising the step of:
identifying a hydrocarbon sweet spot comprising the steps of:
determining a carbon dioxide content of a gas sample retrieved from the hydrocarbon-bearing formation;
determining an isotopic signature of carbon dioxide of the gas sample, and
obtaining a gas flow rate of the hydrocarbon-bearing formation.

2. The method of claim 1 , where the carbon dioxide content of the gas sample has a mole percentage ranging from 9 percent to 20 percent.

3. The method of claim 1 , where the isotopic signature of carbon dioxide of the gas sample has a δ 13 C value greater than −10 per mil.

4. The method of claim 1 , where the gas flow rate is greater than 10 million standard cubic feet per day.

5. The method of claim 1 , where the hydrocarbon-bearing formation is a tight formation.

6. The method of claim 1 , where the gas sample is retrieved via at least one of: wireline formation testing and drill stem testing.

7. The method of claim 1 , the identifying step further comprising the step of:
determining a cutoff range of the carbon dioxide content corresponding to the hydrocarbon sweet spot.

8. The method of claim 7 , where the cutoff range has a mole percentage ranging from 9 percent to 20 percent.

Assignees

• Saudi Arabian Oil Co

Inventors

• Luo Pan
• Lu Peng
• Arouri Khaled

Classifications

• G01N33/241 Primary

  for hydrocarbon content · CPC title

• E21B49/00

  Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells · CPC title

• E21B49/0875

  determining specific fluid parameters · CPC title

• E21B49/003

  by analysing drilling variables or conditions (E21B49/005 takes precedence; systems specially adapted for monitoring a plurality of drilling variables or conditions E21B44/00) · CPC title

• E21B49/082 Primary

  Wire-line fluid samplers (E21B49/083 takes precedence) · CPC title