CO2 Enhanced Oil Recovery and Storage in Reservoirs

CHE384-Energy Technology and Policy

Xi Chen

Nov. 19th, 2007

EOR-Background

Primary recovery Natural pressure, 10% OOIP

Secondary recovery Injection of water or gas, 20-40%

OOIP Tertiary or enhanced oil recovery

Aiming at recovery of 30%-60% OOIP

Categories of EOR

Thermal recovery Steam flooding, ~50% of EOR

production Chemical injection

Polymer/water flooding, <1% Gas injection ~50%

immiscible flooding: CH4, N2 miscible flooding : CO2Process

Ult. Recovery% OOIP

Utilization

Miscible 10-15 10 MCF/bbl

Immiscible 5-10 10 MCF/bbl

Lecture notes from

Dr. Larry W. Lake

EOR by CO2 flooding

Advantages of CO2 flooding Dense fluid over much of the range of

pressure and temperature in reservoirs Low MMP (minimum miscibility

pressure) and high miscibility with oil Low mutual solubility with water Low cost and abundance

Naturally occuring source Environmental benefit if industrial CO2

is used and stored in reservoirs Capture and sequestration of CO2 from

combustion of fossil fuel

Source: Oil & Gas Journal

206,000 barrels per day in 2004 = 4% of the Nation’s total.

Screening criteria for application of CO2 miscible flood

Gozalpour, “CO2 EOR and Storage in Oil Reservoirs”, 2005,Oil & Gas Science and Technology – Rev. IFP, Vol. 60 (2005), No. 3, pp. 537-546

Optimum reservoir parameters and weighting factorsfor ranking oil reservoirs suitable for CO2 EOR

Rivas, O. et al. (1992) Ranking Reservoirs for Carbon DioxideFlooding Processes.

Technical challenge Poor sweep efficiency

Gravity override Mobility contrast Reservoir heterogeneity

CO2 related problem Corrosion on facilities Solid deposition in reservoir formation

Well spacing Greater spacing causes sweep efficiency

reduction

CO2 mobility control

Foam mixed surfactants as foaming agent

Thickening agent Fluorinated compound or polymer

(good solubility in CO2) Chemical gels

In-situ gelation of polymer to lower permeability

Most favorable site for storage Dense webs of seismic and well for

long-term trap Surface and subsurface infrastructure

readily converted for CO2 distribution and injection

Less costly

CO2 Storage in Reservoirs

CO2 Storage in Reservoirs

CO2 capacity of a reservoir: Theoretically, equal to the volume

previously occupied by the produced oil and water

Other factor: Water invasion, gravity segregation, reservoir heterogeneity and CO2 dissolution

Reservoir type, depth, size and safety of CO2 storage

Economics Cost of CO2 from different sources:

Naturally occuring CO2: $14/t Pure anthropogenic CO2 from chemical plant: $18/t Capture and processing of CO2 from coal fired plant: $18-

54/t

CO2 utilization efficiency: 4~8 Mscf/bbl (0.2~0.5t/bbl)

Transportation cost: $0.5~1.2/Mscf Operation cost: $2-3/bbl Economical even at a oil price of $40/bbl. CO2 storage credit ($2.5/Mscf) makes it more

economical for producers.

Lako, P. (2002) Options for CO2 Sequestration and EnhancedFuel Supply.

Summary Combination of CO2 EOR and storage in

reservoirs provides a bridge between reducing greenhouse gases from industrial waste streams and the beneficial use of CO2 injection for increasing oil and gas recovery.