PETROLEUM DEVELOPMENT GEOLOGY WELL TEST

Well Test Objectives
1. Identify and Obtain reservoir fluids; oil, gas
& water
2. Determine basic reservoir parametes;
productivity (PI), permeability(k), skin (S),
initial Resv. Pressure (P*) & Resv. Temp.
3. Well potential & deliverability (gas well) : It
may be mandatory to proof field
commerciality
4. Boundary & irregular conditions Reservoir
(GOC, OWC & Reservoir Limit)


WELL TESTING METHODS
• HOLE CONDITION:
– OPEN HOLE
– CASED HOLE

• TOOLS RUN IN HOLE :
– WIRELINE TESTING : RFT, MDT & DST (IT WAS)
– PRODUCTION TEST WITH COMPLETION STRING
IN PLACE : DST


WELL TESTING SCHEMATIC
at
Cased Hole

Surface Test Equipment

Subsea Safety
Equipment

Downhole Test
Equipment & Tool
DST & TCP


DOWNHOLE TESTING EQUIPMENT

Open-Hole Sampling Equipment
RDT & RCI are equivalent with RFT/MDT
Formation Test Tool (FTT) sample
chambers hold 420cc to 3 gallons of
reservoir fluid depending on make and
model.
Open hole samples aid production and
facility designs and are sometimes used
for PVT studies.

Baker RCI®

Halliburton RDT®


1ST GENERATION

RFT
REPEATED FORMATION TESTER
- unlimited pressure survey

- 1 to 2 fluid sampling

2ND GENERATION

MDT
MODULAR FORMATION DINAMIC
TESTER
- unlimited pressure survey
- many fluid sampling (unlimited?)
- able to identify fluid type
- able to replace(pump out)
unrequired fluid sample
SCHLUMBERGER


DOWNHOLE TESTING
EQUIPMENT

RFT / MDT


Mud pressure

Reservoir pressure

Build-up pressure

Example RFT Record

• To identify the reservoir
pressure
• To identify the fluid content
• To estimate the permeability
• To estimate the productifity
• To define the fluid contact (OWC,
OGC and GWC if any)


Fluid Contact Determination
with fluid gradient from RFT
Oil
Gra

er
at

7
.36
nt 0
die

W

t
i/f
ps

depth

33
.4

OWC

water

RFT depth

pressure

/ft
psi

t0
en
di
ra
G

oil



• Clean up (flow)
• Shut-in
• Main flow (one period or
flow-after-flow, flowing
test with 4 to 5 different
choke size)

• Main Build –up (shut-in)


Selective Layer Testing
26”

20 ft @ 500’

17 1/2”

9 5/8” @ 15500’
12 1/4”

Layer A

Layer B
8 1/2”

7” @ 17690’



[ [psia]
psia]

Example :

4050
4050

Pressure Testing Result

K = 375 mD
S = 21 P = 4200 psia

Pressure, psia

Build up data analysis
Sanding Control
Test

Production Period
[[Mscf/D]
M scf /D]

45000
45000

Build up period
rates
40
40

60
60

80
80

Testing time, hrs

100
100

120
120


Well Productivity
IPR plot

3500

1500

Pressure, psi

AOFP = 344 MMscf/d
CGR = 24.5 STB/MMscf/d

Tested gas and condensate rates can be
increased to 125 MMscf/D and 3100 BPD

Gas Rate, Mscf/d
50000

1.5E+5

2.5E+5

2.5E+5

3.5E+5


Testing Risk
Factors
̇ Layers communication due to
poor cement bond
̇ High pressure and temperatures
(over 350°F)
̇ Pressure and fluid loss through
packers
̇ Annulus-tubing fluid
communication
̇ Water coning or sanding
̇ Layers crossflow


THE ROLE of
WELLSITE/DEVELOPMENT GEOLOGIST (DG)
in WELL TESTING
OPEN HOLE TESTING

CASED HOLE TESTING

with RFT/MDT

with DST

DG Propose/selects the testing/perforation sand, interval and depth
Estimate the reservoir fluid contents and it’s static pressure
Provide the reservoir rock parameter for testing analysis such as lithology, porosity
and permeability if any (from log, or qualitative)
Stop the testing when unsafe operation

Testing Engineer (TE) decision

Decide testing duration

TE decide flow & shut-in periods. TE also
selects choke size for flow testing.

Select taken fluid sample

TE decide fluid sampling methods. And
responsible for fluid sample handling

As Operation Witness will validate &
analyse the result

TE is prime Operation Witness and will
validate & analyse the testing result.
DG & TE will be along selecting the
perforation method


PERFORATION
1.

THROUGH CASING GUN å
Hyperjet/HSD(high shot density)

2.

THROUGH TUBING GUN å Enerjet

3.

TCP (Tubing Conveyed Perforation)




PERF. At Net pay

1.

Define the perforation intervals at
porous zone & hydrocarbon zone
(pay zone.

2.

Evaluate and prepare the perforation
design such as gun type, size, SPF
(shot per ft), Spacing (angle between
two shots), charge/explosive type;
penetration deep and entrance hole.

3.

Perforation environment (fluid type
in the hole); using mud or brine
water or special completion fluid,
under/over balance.

4.

Witness the gun loading, correlation,
shooting result (whether all charges
exploded or not) å “SAFETY FIRST”