Application of XRay CT to Investigate Effect of Rock Heterogeneity and Injection Rates During CO2 Flood Process

Experiment OutlinePrepare Core Scan Dry Core CO 2 Saturated Core Scans Dope Oil Saturate in Vacuum Chamber Experiment Procedure... Pressure LineGas Chromatograph Back Pressure Regulato

Application of X-Ray CT to Investigate Effect of Rock

Heterogeneity and Injection Rates During CO 2

Flood Process

Deepak Chakravarthy Master’s Division

widely used!

Why

?

 Sandstone (55% of current floods)

 Carbonates (35% of current floods)

 Others (about 10%)

 Oil saturation from <20% to 85% at start of flood

 Average So for current flood is 55%

 Water cuts as high as 98% at start

Broad Applicability

Investigate mechanisms of oil

bypass during CO 2 flooding

X-Ray CT Scanner

CT Scanner

Experiment Outline

Prepare Core

Scan Dry Core

CO 2 Saturated Core Scans Dope Oil

Saturate in Vacuum Chamber Experiment

Procedure

Pressure Line

Gas Chromatograph

Back Pressure

Regulator

Pressure Transducer

Pressure Transducer

Data Acquisition System

Graduated

Cylinder

Pressure Gauge

Pressure Gauge

Flow Control Valve

Computer

Flow Dividing Valve

Oil Accumulator

CO2 Accumulator

Injection Pump Wet test meter

 Highest Injection Rate - 0.09

cc/min

Experiment Outline

Experiment Summary

 Highest Injection Rate - 0.09

 Highest Injection Rate - 0.09

cc/min

 Lowest Injection Rate - 0.03 cc/min

(fractured) core - 0.03 cc/min

Experiment Outline

Experiment Summary

Dry core scans with bright blue regions indicating higher CT numbers - i.e higher density

Oil saturated core scans with red color

blue spot at the center

CT Scans at 25 minutes after start of

CT Scans at 35 minutes after start of injection

CT Scans at 60 minutes after CO2

CT Scans at 120 minutes after CO2 injection

Results





Sample y

x

dry y x

Sample y

x

Sample y

x

CT

CT

CT S



1000

,

, ,

Sample y

x

Sample y

x

CT

CT CT



CO2 Saturation – 15 Minutes CO2 Saturation – 25 Minutes

Injection rate = 0.09 cc/min

Oil Saturated Core

Injection Rate = 0.09 cc/min

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Injection Rate = 0.03 cc/min

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Fractured Core – 100% Oil Saturated

Results

CO2 flowing through fracture

Results

CO2 flow is confirmed by lower CT number at the fracture

Results

Results

play an important role in affecting oil recovery and breakthrough.

 Heterogeneity and injection rates

play an important role in affecting oil recovery and breakthrough.

bypass are observed at high injection rates.

 Heterogeneity and injection rates

play an important role in affecting oil recovery and breakthrough.

 Early breakthrough and higher oil

bypass are observed at high injection rates.

before the start of injection

 Injection rates must be optimized

before the start of injection

occurs mainly through the fractures

 Injection rates must be optimized

before the start of injection

 In a fractured system, fluid flow

occurs mainly through the fractures.

required for the injection fluid to

penetrate the matrix.

Foam and conformance control (polymer) is necessary to increase sweep efficiency and mitigate the bypassing during CO2 injection in the fractured system.