EOR Technique Presentation

Simultaneous Injection of Miscible Gas and Polymer to improve Oil

Recovery and Sweep Efficiency from Layered Carbonate Reservoirs

Present by Mr.Wasin Saengnumpong

SPE 129645: Shehadeh K. Masalmeh, H. Hillgartner, R. Al Mjeni, X.D. Jing (2010)

Contents

Problem assessment & motivation

Objective

Study Approach

Results & Discussion

Conclusion

Problem Assessment

Highly heterogeneous oil-wet carbonate and layered reservoir

Part of the Oman oil fields

UPPER ZONE: STOIIP = 40%

LOWER ZONE: STOIIP = 60%

KU > KL

Problem Assessment & Past studied

Masalmeh et al., 2004, 2007, 2008 : Waterflooding performance

Problem: Low sweep eff. For lower zone due to the “Water override phenomenon” is caused by capillary forces which act as a vertical barrier and counteracts gravity force in case where permeability varies between layers for mixed to oil-wet reservoirs.

Problem Assessment & Motivation

Are there any way to increase the vertical sweep eff. and consequently the total oil recovery ?

Objective

To Compare different IOR/EOR technique including

1. Water flooding

2. Gas injection

- Acid gas (75% H2S and 25% CO2)

- CO2

- Methane

3. Simultaneous injection of gas and water

- Water and Miscible gas

- Viscous water (Polymer) and Miscible gas (SIMGAP)

By Using the Numerical Reservoir Simulation

Study Approach: Reservoir Simulation

Simulation Model Description

Cut-out 3-D history matched reservoir model: 25×25×48 Blocks, 20×20 m/block

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                 

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    

Vertical Well: Inverted 5 spot

x

y

Horizontal Well at bottom half of the lower zone

x

z

Study Approach: Reservoir & fluid properties

Properties of reservoir fluids and injected gases at res. Conditions of pressure and temperature

Pi = 4200 psi

Tres = 250 F

Formation water salinity > 200,000 ppm

Results

Part 1 Water flooding & Gas injection

Part 2 SIMGAP

Comparison of IOR/EOR technique

Result Part 1

Oil recovery factor of Upper & Lower zone

Result Part 1

Total recovery

Result Part 1

(4)

(4)

R=2 R=4 R=7

(4)

(4)

Total oil recovery factor : SWAG

Discussion Part 1

Problem : Displacing phase trend to migrate upward to Upper zone (Low pressure gradient zone)

UPPER ZONE: Low P/L

LOWER ZONE: High P/L

Discussion Part 1

Solution : Control P/L condition

UPPER ZONE: Low P/L

LOWER ZONE: High P/L

(P/L)LOWER =< (P/L)UPPER

We can increase W

Result Part 2

Part 1 Water flooding & Gas injection

Part 2 SIMGAP

Comparison of IOR/EOR technique

Introduction to SIMGAP

Pressure Gradient control

=

(P/L)LOWER =< (P/L)UPPER

First condition

Increase W by using Polymer (Viscosified Water)

Introduction to SIMGAP

Second condition : Water front must slightly move faster than gas front

=

Introduction to SIMGAP

Second condition : Water front must slightly move faster than gas front

=

Result and Discussion Part 2

Physical scale

Recovery factor : Simultaneous Injection of Acid Gas and Polymer

Result and Discussion Part 2

Physical scale

Recovery factor : Simultaneous Injection of CO2 and Polymer

Conclusion

1. Water flooding and gas injection lead to poor sweep of the lower zone for this kind

of reservoir.

2. SWAG give a little advantage over water injection, but this come with early gas

break-through, and high cost of gas handling.

3. SIMGAP shows significant sweep of the lower zone and lead to high oil recovery

compare to water flooding this method also has much lower water cut and GOR

compared to water flooding and gas injection, respectively.

4. SIMGAP method can adjust the viscosity of injected fluid and injection rate to

control sweep performance of different heterogeneity levels.

5. SIMGAP need more detail study such as chemical properties under reservoir

conditions, complexity of geological and the pilot testing before implement on real

field in order to ensure the successful of a project