American Oil and Gas Reporter - April 2016 - 44

SpecialReport: GOM Field Development

tester station for capturing a reservoir
fluid sample and DFA for determining
in-situ downhole fluid properties and
connectivity analysis (see OTC 25173,
presented at the 2014 Offshore Technology
Conference). Focused sampling technology
is implemented to acquire clean fluid
samples with shorter pumping durations
(see IPTC 17931, presented at the 2014
International Petroleum Technology Conference).
The bottom horizontal track shows
the initial flow of a mixture of in-situ
fluid, drilling mud, and other high-absorption fluids at the start of pumping.
To the right, the extended green band on
the white background indicates the flow
of cleaner in-situ fluid. The middle track
shows an abbreviated oil composition
along with pump rates, with the sample
line rate in green and the guard line rate
in pink. The uppermost track shows fluid
gas-to-oil ratio from the sample line analyzer (green) and guard line (pink), and
in-situ density (blue).
Soon after the flow is split, the fluid
properties are stabilized, indicating clean
formation fluid, and the sample bottles
are filled. In this well, stable fluid properties were observed after only 30 minutes
of pumping, and clean samples were acquired subsequently (as confirmed by
laboratory-measured contamination of
less than 1 percent).
Wireline formation testing was accompanied by extensive pressure measurement while acquiring formation
pressure and pumping fluid in the reservoir

FIGURE 3B
Close-Up of Mass-Transport Deposit

Reservoir Testing
Extensive wireline formation testing
was performed in the field for DFA and
reservoir flow characteristics. Figure 4 is
an example of a typical wireline formation

FIGURE 4
Wireline Formation Tester DFA Plot During Focused Sampling
IFA_1
GOR_IFA1

2,800

GOR_lFA2

RODRRHO_IFA1

Low Quality

Medium Quality

High Quality

1.00
0.95

2,600

0.90

Fluid GOR
ft3/bbl

2,400

0.85
0.80

2,200

0.75
0.70

2,000

0.65
0.60

1,800
1,600

0.55
CHCR_IFA1(4)

1.0

CHCR_IFA1(0)

CHCR_IFA1(1)

CHCR_IFA1(2)

CHCR_IFA1(3)

POFR

0.50

POFR2

14

Oil Composition
Unitless

0.8

12
10

0.6

8

0.4

6

0.2

4
2

0.0
LEGS_IFA1

1.0

POTCV

WATF_IFA1

0

HAFF_IFA1

0.8

6

0.6

4

0.4

2

0.2
0.0

0
0

30

60
Time (min)

Flow Volume
Gal

Fluid Type
Unitless

Flow Rates
om3/s

44 THE AMERICAN OIL & GAS REPORTER

acterization.

In situ Density
g/cm3

observed in the shaly sediments, again
implying mass transport deposits.
A close-up view of one of the mass
transport deposits observed in the well
shows the fabric of the deposit (Figure
3B). The large patches observed in the
static images are broken beds, and the
smaller dark areas are clasts.
Borehole geological images resolve
one-inch-size features and provide the
detail within packages seen by seismic
and borehole seismic data. It can be interpreted that flat dips from the seismic
data are of regional surfaces and represent
the tops and bases of the mass transport
deposit packages, between which the
sand packages exist. Borehole images
help us understand the nature of each
package.
One concern that arises is the continuity
of a sand body when it is adjacent to or
in the middle of mass transport deposits.
Advanced pressure measurement and
downhole fluid analysis (DFA) strategies
were undertaken in the well, and the resulting data were integrated with geological
and geophysical data as part of the formation evaluation program to help address
this concern and improve reservoir char-
American Oil and Gas Reporter - April 2016

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