Method for predicting occurrence of microquartz in a basin

Patent metadata

Field	Value
Publication number	US-9869797-B2
Application number	US-201414446110-A
Country	US
Kind code	B2
Filing date	Jul 29, 2014
Priority date	Aug 23, 2013
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

A method, including: obtaining a grain size for amorphous silica associated with a basin and a grain size for quartz associated with the basin; obtaining kinetics of silica dissolution corresponding to the basin and quartz precipitation corresponding to the basin; determining, with a processor, a concentration of amorphous silica in water based on the grain size for amorphous silica, the grain size for quartz, and the kinetics of silica dissolution and quartz precipitation; comparing, with the processor, the concentration of amorphous silica in water to an amorphous silica saturation condition; and determining, with the processor, a presence of microquartz based on a result of the comparing.

First claim

What is claimed is:

1. A method, comprising:
obtaining a grain size for amorphous silica associated with a basin and a grain size for quartz associated with the basin;
obtaining kinetics of silica dissolution corresponding to the basin and quartz precipitation corresponding to the basin;
determining, with a processor, a concentration of amorphous silica in water based on the grain size for amorphous silica, the grain size for quartz, and the kinetics of silica dissolution and quartz precipitation;
comparing, with the processor, the concentration of amorphous silica in water to an amorphous silica saturation condition;
determining, with the processor, a presence of microquartz based on a result of the comparing; and
generating a model for the basin, where the model assigns a probability of the presence of microquartz in a particular zone of the basin based on the determined presence of microquartz.

2. The method of claim 1 , further comprising:
obtaining a burial rate for at least a portion of the basin, the burial rate providing a heat flow model, wherein the kinetics are dependent on temperature from the heat flow model.

3. The method of claim 2 , wherein the grain size for amorphous silica, the grain size for quartz, the kinetics of silica dissolution and quartz precipitation, and the burial rate are derived from a geologic setting of the basin.

4. The method of claim 1 , wherein:
the comparing includes determining a difference between the concentration of amorphous silica in water and amorphous silica saturation condition, and
the determining the presence of microquartz includes comparing the difference to a predetermined threshold.

5. The method of claim 1 , wherein the presence of microquartz is determined in response to the difference being above the predetermined threshold.

6. The method of claim 4 , wherein the predetermined threshold is at or above 0.5 times the amorphous silica saturation condition.

7. The method of claim 1 , further comprising:
obtaining an equilibrium constant for the amorphous silica in water, wherein:
the equilibrium constant for the amorphous silica in water is additionally used in determining the concentration of amorphous silica in water.

8. The method of claim 1 , wherein the amorphous silica is biogenic silica.

9. The method for claim 1 , further comprising:
obtaining a plurality of grain sizes for amorphous silica, each of the plurality of grain sizes being associated with a probability of occurring in the basin; and
determining a probability of a presence of microquartz corresponding to each of the plurality of grain sizes.

10. The method for claim 1 , further comprising:
obtaining a plurality of burial rates, each of the burial rates being associated with a probability of occurring in the basin; and
determining a probability of a presence of microquartz corresponding to each of the plurality of burial rates.

11. The method of claim 1 , further comprising:
obtaining identification of a plurality of silica sources, each of the plurality of silica sources being associated with a probability of occurring in the basin; and
determining a probability of a presence of microquartz corresponding to each of the plurality of silica sources.

12. The method of claim 11 , wherein the plurality of silica sources includes amorphous silica sources of colloidal silica, diatoms, or silica sponge.

13. The method of claim 1 , further comprising:
obtaining a seismic data volume representing a subsurface region of a zone of the basin determined to include microquartz;
obtaining a prediction of the potential for hydrocarbon accumulations in the subsurface; and
in response to a positive prediction of hydrocarbon potential, drilling a well into the subsurface region corresponding to the zone of the basin determined to comprise microquartz, and producing hydrocarbons.

14. A method, comprising:
obtaining a grain size for silica associated with a basin and a grain size for quartz associated with the basin;
obtaining kinetics of silica dissolution corresponding to the basin and quartz precipitation corresponding to the basin;
determining, with a processor, a concentration of silica in water based on the grain size for silica, the grain size for quartz, and kinetics of silica dissolution and quartz precipitation;
determining, with the processor, a presence of microquartz based on the concentration of silica in water; and
identifying zones in the basin having high reservoir quality based on the presence of microquartz.

15. A method, comprising:
obtaining, for a basin with zones that have each undergone a different thermal history, a corresponding plurality of burial rates;
determining, with a processor, a relative likelihood that each of the zones includes microquartz based on the corresponding plurality of burial rates;
determining a reservoir quality potential of one or more zones of the basin; and
updating a basin model with the reservoir quality potential for the one or more zones.

16. The method of claim 1 , further comprising determining a potential for hydrocarbon accumulations in one or more zones of the basin based on the probability of the presence of microquartz.

17. The method of claim 16 , further comprising causing a well to be drilled in the zone of the basin with the highest potential for hydrocarbon accumulation.

Assignees

• King Jr Hubert E
• Cameron Stephen D
• French Marsha W
• Exxonmobil Upstream Res Co

Inventors

• King Jr Hubert E
• Cameron Stephen D
• French Marsha W

Classifications

• G01V99/005 Primary

  Physics · mapped topic

• G01V20/00 Primary

  Geomodelling in general · CPC title