Effect of WAG injection and rock wettability on oil recovery during CO/sub 2/ flooding

Journal Article · Mon Feb 01 04:00:00 EST 1988 · SPE (Society of Petroleum Engineers) Reserv. Eng.; (United States)

OSTI ID:5340197

Huang, E T.S.; Holm, L W

Previous studies to determine the extent of oil trapping by water during CO/sub 2/ water-alternating-gas (WAG) flooding have shown that rock wettability strongly affects this trapping. A significant trapping occurs in water-wet rock, and less trapping occurs in oil-wet rock. This paper presents laboratory results of Devonian crude oil displacement from watered-out Berea and reservoir cores by use of continuous CO/sub 2/ injection, single-slug CO/sub 2/ injection (followed by water), and CO/sub 2/ WAG injection at miscible reservoir conditions of 120/sup 0/F and 2,500 psig (49/sup 0/C and 17.2 MPa). The reservoir cores used in this study were mixed-wet (Devonian and Muddy formations) and oil-wet (Tensleep formation). The Berea cores used had their wettability artificially altered to simulate these natural wettabilities. The X-ray photoelectron spectroscopic (XPS) method for measuring carbon content of rock surface was used to provide a qualitative measurement of wettability of the rock samples. The results of the study indicated that the experimental wettability-altering technique came close to duplicating reservoir rock wettability. The oil recovery data at the end of 1 PV fluid injection (continuous CO/sub 2/ or WAG CO/sub 2/) indicated that (1) in preferentially water-wet Berea cores, more than 45% of the waterflood residual oil trapped by CO/sub 2/ WAG; (2) in mixed-wettability Berea cores, 15 to 20% of the waterflood residual oil was trapped; and (3) in oil-wet Berea cores, less than 5% residual oil was trapped.

• Research Organization: Unocal Corp.'s Science and Technology Div. in Brea, CA (US)
• OSTI ID: 5340197
• Journal Information: SPE (Society of Petroleum Engineers) Reserv. Eng.; (United States), Journal Name: SPE (Society of Petroleum Engineers) Reserv. Eng.; (United States) Vol. 3:1; ISSN SREEE
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020300* -- Petroleum-- Drilling & Production
CARBON DIOXIDE INJECTION
DISPLACEMENT FLUIDS
ENERGY SOURCES
ENHANCED RECOVERY
FLUID INJECTION
FLUIDS
FOSSIL FUELS
FUELS
MISCIBLE-PHASE DISPLACEMENT
OIL WELLS
PETROLEUM
RECOVERY
RESERVOIR ROCK
ROCK-FLUID INTERACTIONS
SPECTROSCOPY
STIMULATION
WATERFLOODING
WELL STIMULATION
WELLS
WETTABILITY
X-RAY SPECTROSCOPY