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UNIVERSITI TE KNOLOGI PLTRONAS
COURSE
A11ý
ýi rr
PAB2084 WELL LOGGING AND FORMATION
EVALUATION
DATE 7th SEPTEMBER 2011 (WEDNESDAY)
TIME 9.40 AM -- 12.00 NOON (3 HOURS)
INSTRUCTIONS TU CANDIDATES
. Answer ALL questions from the Questions Booklet.
2. Begin EACH answer on a new page in the Answer Booklet.
Indicate clearly answers that are cancelled, if any. Where applicable, show clearly steps taken in arriving at the solutions and indicate ALL assumptions. Do not open this Question Booklet until instructed.
Note There are FOURTEEN (14) pages in this Question Booklet including
the cover page and Appendices.
1I
UNIVERSITI
Universiti Teknoiogi PETRONAS
PAB 2084
I. a. Explain differences between total porosity and effective porosity.
[4 marks]
b. Sketch an appropriate diagram and mark the following depth references;
measured depth (MD), true vertical depth (ND), measured depth subsea
(MDSS) and true vertical depth subsea (TVDSS). [4 marks]
2. a. Define the SP log. [2 marks]
b. Describe the conditions under which the SP deflection wou'd be:
L To the left. [2 marks]
ii. To the right. [2 marks]
C. Describe in detail the electrochemical effect causing the deflection of SP
curve. [4 marks]
2
PAB 2084
3. a. Explain how the slowing dawn of neutron indicates the formation
porosity.
[4 marks]
b. Discuss the common exceptions of the neutron slowing down.
[6 marks]
4. a. Describe the basic principles of formation density tool. [4 marks]
b. Describe haw the number of Gamma Ray collisions is related to
formation porosity. [6 marks]
5. a. Differentiate between resources and reserves.
[Z marks]
b. Calculate the gross rock volume (GRV) for the subsurface structure in
FIGURE Q6.
FIGURE Q6
[6 marks]
3
PAB 2084
C. Using the GRV from part(b), calculate the STOIIP given the following
values:
Not to gross, N7"G = 0.8,
Porosity, 'P = 0.2,
Oil saturation, Sý ý 0.55,
Formation volume factor, F1IF =1.19 RBIBTB.
[4 marks]
4
PAB 2084
6. Drilling operation has been completed for clean clastic section using salt water
mud (FIGURE B). From logging data, we have been informed that NO lithology
correction is needed and we have obtained the following information:
Bottom Hole Temperature (BHT) =1 80° F
Total depth =15,900 ft
Rmt= O. Süohmlm at 80° F
SSP = -90mV
The foflowing is given:
4ýý --_
fl
I) -p )ý Oý -p2 ma log ýna f
SW =F K Rw I Rr
F=al ýPm (Use a- O62, n2,2, and in=2J5)
5
PAB 2084
CR i. 4°. i ý"ýý
r-T-rm
CNL , ýcý 4!
VT 1
ý.
t. 2 MSF1 [cn ý
ý. .ý1, i 1ýYý
LLS ýu ý1 i` ýý
r--r-- FOC
's
1'i 1f
FIGURE B
iý LID ýý
ýýý
1ýýý ý
ýGý TI
ýý ý
6
PAB 2084
a. Predict the potential reservoir, by giving the top, bottom and thickness. [2 marks]
b. Find out the well log reading at zones A, B and C of the reservoir. Please
answer in TABLE B provided in the appendix.
[6 marks]
C. Calculate the formation temperature at depth 8000 ft. [4 marks]
d. Calculate the mud filtrate resistivity, R,, at formation temperature.
[4 marks]
e. Estimate the formation water resistivity, R} and its salinity at formation
temperature.
[6 marks]
f. Calculate the porosity at the specified zones by two methods and the average.
Please answer in TABLE B provided in the appendix.
[8 marks]
9 Estimate the porosity and sithology at the specified zones. [8 marks]
7
PAB 2084
h. Calculate the water saturation, Sw and hydrocarbon saturation, S, at the
specified zones using the simple Archie equation.
[8 marks]
L Comment on the results obtained; porosity, lithology, fluid types, and contacts . [4 marks]
- END OF PAPER -
8
PAB 2084
APPENDIX
ESTIMATION OF FORMATION TEMPERATURE (Lintar cnacene A, wmed)
T(WPEAA"I'URC tC¬ýLSiUS)
I ý,: JQO
-� 14 P00
W
ý '$, p0' Z :'
ý ?, cwO
fEMPýRA! l1IE 1fAHVi. iE114
EXAMPLE: BIiTIi2XPat 11OOO' {point A). Týperatur* t $rOX'" Ii 167F (P'Oifkl B).
T. mpýraturý ýrcrdirrnt Corw. riiorrxr 1 °i'11 OQ Fk ý 1823°C/ 1 cx m 1 °C! 1! »m ,:
Ü. 54$60Fi IOc3 ft
9
te'ý
ýFO9Q
L5OG
S, QVci
s, oo
PAB 2084
APPENDIX
RESISTIVITY NOMOGRAPH FOR NaCI SOLUTIONS
R (thr
-r. ol
4F oC 5O 10
Conversion approximated by: 60
70
80
90
I00
150
200
300
T, +6.77 U 20 R2= R1 ýýý
ýo T1# 8.77 (Arpt)
30
40
or
R2=R1(1-2--L ý fiý+2Iof !
kPPm 9i9 @75°F
ý 173050ý0
10000 ýoo
80 60
40
30
20
5000 4000 3000
2400
. O2
. 03
. 04
. 05
. 06
. 08 0.1
.2 1000 # 50 ý $ý. 3
60
80
I00
250- 12Ü
I4O
300 16ü
18O
400 200 220
240 X00 260
500 400 300
200
.4
.5
.ö
.B I. 0
I00
50 40
30
20
© Schlumberger
2
3
4
ä 6
H
Iö
20
Gene ll; i: 4ý
10
e 6
4
3
2
ý
.8
.8
ýý
�3 2
10
APPENDlX
DETERMINATION FROM THE SSP
STATIC sP mV
-204-r
11
ý
For predominantly sodium chloride muds determine Rmr 05 follows:
a. If Rmf at 75° is greater than 0.1 ohm-m, correct Rmt to formation tempera- ture using Gen-9, and use Rmý ,
0.85 Rjn.
b. If Rr at 75° is less than 4.1 ohm-rn, use SP-2 to derive a value of Rmtý at formation temperature.
Rmfeq lRweq .4 ,r
B Rmfeq I . 01- r
too- 1.0 (3)
© Schiumberger
PAB 2084
PAB 2084
APPENDIX
Rw VERSUS Rw, q AND FORMATION TEMPERATURE 3
, -ý75°F N-SATURATION
AI 402 ß3 AS 0.1 0ý2 0.3 0.5 I. Q 2 345 RW Oº Rmf
(ohrnrn)
UI. Ihe solid linu of *Is chart for predominantly NaCl wainr. The dobed ýimas are approximate for ^'averafresh formation rraterý (where effects of alts other than NaCl become ýignificcant), The dathed portions may also be ued for gyp»base mud Mt, rates Example: R, ý . 025 at 15O°F. From chart, ýý ý ýý
Special procerdars for muds containing Ca or Mg in soltrwioi are dlscUIII. d in the rsf"r. nce. Urne- baie mud* usually have a neýigibia amount of Ca in solvtion, and may be treated as regular mad typeý.
sPz
ý" I5ý0 F ý
` 100°F \. ___-
ý
r
ý
12
PAB 2084
APPENDIX
POROSITY AND LITHOLOGY DETERMINATION FROM FORMATION DENSITY LOG AND
COMPENSATED NEUTRON LOG (CNL*) SALT WATER, 11QU1D"FILLED HOLES
ýý
0 POüü
, .,.... LYnALITE
w. ý M... #_,.
_.. _ ._.....; - -, ý ,.. , ...., .
r. . -..,... w.... ... ... .º... . ... ..... ..... .ý.. ,
-rI
Jo 20 30
('ýCNL)COP NEUTRON POROSITY INDEX, p. u (APPARENT LIMESTONE POROS'1tY)
..,.,.,., t,
13
OD 0 ý
m 4:
. 0
a z w cL Li. ý
ý
W ý ý
ý
F-
ý ý ý
cl) ý
ý ý
:� 0
ý ý
ý ý
ro «h+
D ý
I
ý ý
ý
ci < to 0 ý
N
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a
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