Page 29 - Hybrid Enhanced Oil Recovery Using Smart Waterflooding

CHAPTER 1 History of Low-Salinity and Smart Waterflood 21

The target reservoir is the sandstone formation and has The early application potentially expects cost cuttings in

the temperature with 88 C. In the first trial of LSWF, the terms of water handling, disposal, and injection.
log-inject-log field test and SWCTT are performed based Abdulla et al. (2013) and Al-Qattan et al. (2018) have
on the experimental and numerical simulation works. reported the field tests of LSWF as EOR application in
Referring the experimental and simulation results, a the Burgan field. Abdulla et al. (2013) described a
further technical-economical evaluation provides the first SWCTT application of LSWF in the Burgan field.
salinity level for LSWF. Compared with the case of the The sole compatibility test between freshwater injection
seawater injection, the SWCTT reports the negligible and core is carried out as a preliminary test. The target
reducing residual oil saturation by LSWF. Another giant reservoir is the rock type 1, which is the clean and
on-shore brownfield in North Africa is also tested for best quality rock with the least clay. In terms of wetta-
LSWF efficiency. The SWCTT is implemented to quan- bility modification effects by LSWF, the study mainly
tify the LSWF potential in the field. Callegaro et al. investigated the residual oil saturation changes without
(2015) reported the detailed results of the field trial in considering relative permeability curve changes. Two
the brownfield. The reservoir has temperature in the wells, BG-A1 in South of the Wara and BG-A2 in the

ranges of 76e83 C and viscous oil in the ranges of South-West of the 3SU, are candidate wells for SWCTT.
3e8 cp at the reservoir condition. The original forma- The produced water and low-salinity water are injected
tion salinity is higher than 220 g/L. The primary deple- into each well, and SWCTT is carried out following the
tion initiates in 1955, and the secondary seawater injections. The test results of BG-A2 have a good quality,
injection of 39 g/L salinity is implemented in 1985. but the results of BG-A1 have some errors to measure
When the secondary injection of seawater becomes inef- the tracers from SWCTT. The tracer data sets of the
fective with the high water-cut and moderate recovery, it SWCTTs are interpreted with five methods: (1) three-
is initiated to evaluate the prospect of the another IOR/ layer tracer flow simulation with flow irreversibility;
EOR technology implementation. The LSWF is evalu- (2) one-layer tracer flow simulation with cross-flow;
ated for the tertiary recovery in the field. The positive (3) simple calculations from peak arrival times/vol-
experimental results of LSWF coreflooding lead to the umes; (4) direct shift; and (5) full reservoir simulation.
SWCTT implementation of LSWF in the field. The field The two methods of simple calculations from peak
tests of SWCTT measure the residual oil saturation after arrival times/volumes and reservoir simulation show
seawater injection and LSWF. Interpretation on the unclear interpretations because of an unclear peak of
SWCTT tracer data shows that the LSWF reduces resid- tracer data and the complex input parameters of
ual oil saturation of 5%e11%, compared with seawater reservoir simulation. In the SWCTTs of BG-A1, the
injection. three-layer tracer flow simulation calculates the residual
The Burgan field in Kuwait is the second largest in oil saturation of about 0.12, which is higher than the
the world and the largest clastic reservoir. It is mainly residual oil saturations calculated by other methods.
composed of five giant reservoirs, Wara sandstone, Bur- The SWCTTs from BG-A2 provide relatively consistent
gan sandstone, Mauddud limestone, Minagish Oolite residual oil saturation regardless of interpretation
limestone, and Marrat carbonate. The Burgan sandstone methods. This study concluded that the applications
has the subsections of 3SU, 3SM, 3SL, and 4S. The 3SM of LSWF in BG-A1 and BG-A2 approximately reduce
and 4S have good quality with up to 10,000 md. The the average residual oil saturation by 0.3 in the clean
3SU and 3SL sections of Burgan sandstone and Wara and good reservoir in Burgan field. As reported by
sandstone are more heterogeneous. Kuwait Oil Com- Al-Qattan et al. (2018), these results lead to the imple-
pany (KOC) deployed the field trial of LSWF in the Bur- mentation of additional SWCTT of LSWF in rock type 2
gan field. The second largest reservoir has been of the Wara formation. The rock type 2 is characterized
produced since 1946. Because the field has the strong with higher clay content expecting the more potential
natural aquifer below and costs little for drilling, the of LSWF. The test well, Well A, shows the oil cut of
production is most economic until 1988. At that time, approximately 66% before SWCTT trial. The PV of
water production is observed and additional facilities target depth of SWCTT is estimated with 500 bbls.
are introduced with artificial lift. The water production The target interval of 16 ft has an average porosity of
reaches the 23% of liquid production in 2012. To 0.23, and the radius of investigation is about 15.6 ft.
extend the life of Burgan field, KOC reviews the early In the well, the high-salinity water injection of up to
application of EOR technology appropriate to the field. 148,000 ppm TDS displaces all movable oil, before