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The Selection of Optimized PDC Bits in the12 ¼”
Hole Section (Upper Part) of Gas Fields
Aryan Javanmardian Dana Bit & Down-Hole Co. / Drilling Optimization Dep., Tehran, Iran
Email: [email protected]
Vahab Hassani and Pedram Rafiee Dana Bit & Down-Hole Co. / Drilling Optimization Dep., Tehran, Iran
Dana Drilling Co. / Geology Dep., Tehran, Iran
Abstract—Selection of the optimized bit is the most
important factor to prevent the high Cost per meter and
approaching the long interval drilling and ROP. The goal of
this paper is to investigate the PDC bit performance in the
12 ¼” hole section From Hith-Eva.B for one of the gas fields
in Iran. The interval is mainly composed of thick white
anhydrite beds, dolomitic streaks and limestone. It was also
observed traces of cherts in the layers of gray claystone
throughout the interval. At this interval, the optimized one
is PDC with 8 blades of 13mm cutter size, Nozzle Quantity:
8 and 30.7 square inches Junk Slot Area. The average $/m is
good amount and ROP for this bit is 12 m/h respectively for
drilling 4 various wells. The most important feature for this
bit is related to hard formation with high compressive
strength. The recommendations that must be noticed for
this bit are manufactured based on matrix body with heavy
cutter layout density, Force balanced design ensures less
vibration while drilling, Special enhanced gauge protection
and dynamic flow simulating technology is used for
hydraulic design to ensure optimum bottom hole flow
pattern and anti-balling and benefit for increasing ROP.
Index Terms—PDC bit, optimization, cost per meter, rate of
penetration, bit nozzle
I. INTRODUCTION
The South Pars gas field was discovered in 1990. It is
located on the Qatar Arc in Iranian part of the Persian
Gulf approximately 100Km from Assaluyeh, 105 km
from Qatar and 330Km from Dubai.
The main Pars gas field is an anticline which its axis is
elongated and curved from the North (in Qatar) to the
Northeast. The flanks are dipping 0.5° to the Southeast
and 0.6° to the Northwest.
The hydrocarbon reservoir of the Kangan and Upper
Dalan Formations and equivalent to the Upper Khuff
reservoir in the Arabian plate contain some of the most
important gas reservoir in the Middle East region, as well
as the world. They are Middle-Late Permian to Early
Triassic in age and made up of cycles of carbonate-
evaporite deposits [1]. The Kangan-Upper Dalan
Manuscript received November 29, 2013; revised April 12, 2014.
successions in South Pars Gas Field (and also in the
North Field) include four reservoir units, respectively, K1,
K2, K3 and K4 with increasing depth [2].
A. Geology
Hith Formation from 1706-1850 MD: Hith
Formation is mainly composed of thick anhydrite
beds and thin dolomitic streaks. The age of this
formation is Upper Jurassic. 13 ⅜" Casing was set
10 meter Inside Hith Formation at 1716 meter.
Surmeh Formation from 1706-1850 MD: Surmeh
Formation is Middle to Upper Jurassic in age and
divided into 9 members as following:
Upper Surmeh Member from 1850 to 1974 MD:
This member is mainly composed of light brown
to cream dolomite and white amorphous anhydrite.
The Upper Surmeh Member is Upper Jurassic in
age.
Upper Dolomite Member from 1974 to 2081 MD:
This member is predominantly composed of
limestone and dolomite. There were also observed
some anhydrite at the top of this interval. The
Upper Dolomite Member is Upper Jurassic in age.
Upper Limeston Member from 2081 to 2272 MD:
This member is Middle Jurassic in age and is
composed of light cream to off-white limestone
inter-bedded with hard dolomite.
Cherty zone Member from 2272 to 2422 MD: This
member is Middle Jurassic in age and was entirely
composed of white to off-white limestone inter-
bedded with cream to light brown dolomite.
Middle Limeston Member from 2424 to 2594 MD:
This member is Middle Jurassic in age and was
entirely composed of limestone inter-bedded with
some dolomitic streaks. It was also observed some
black spots in lower part of this formation.
Mand Member from 2594 to 2776 MD: Mand
Member is Middle Jurassic in age. It is entirely
composed of limestone inter-bedded with some
gray to light gray dolomitic streaks in the lower
parts.
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Journal of Industrial and Intelligent Information Vol. 2, No. 4, December 2014
©2014 Engineering and Technology Publishingdoi: 10.12720/jiii.2.4.329-332
Email: {Hassani.Vahab, Rafiee.Pedram }@danaenergy.ir
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Lower Limeston Member from 2776 to 2959 MD:
The age of Lower limestone Member is Middle
Jurassic. It is composed of light gray to cream
limestone and minor light brown to cream
dolomites in the middle part.
Lower Surmeh Shale Member from 2959 to 3075
MD: Lower Surmeh Shale Member is Middle
Jurassic in age. It predominantly is composed of
off-white to gray limestone inter-bedded with
argillaceous limestone, minor gray dolomite and
gray to dark gray elongated shale. Traces of pyrite
have been observed in some interval.
Lithiotis Member from 3075 to 3122 MD: The age
of Lithiotis Member is Middle Jurassic. It mainly
consists of light cream to light gray dolomite with
sucrosic texture. It was also observed some white
to off-white limestone and gray to dark gray
claystone.
Neyriz Formation from 3122 to 3162 MD: Neyriz
Formation mainly consists of gray to light cream
dolomite inter-bedded with thin streaks of
limestone and minor claystone. The age of this
formation is Lower Jurassic.
Upper Dashtak Member from 3162 to 3294 MD:
Upper Dashtak Member mainly consists of
crystalline dolomite inter-bedded with white to
gray argillaceous limestone. It was also observed
some white anhydrite in lower part and some gray
claystone in upper and lower parts of the member.
Evaporate B from 3294 to 3466 MD: Evaporite B
mainly consists of anhydrite with thin dolomitic
beds which becomes locally argillaceous towards
the base.
II. MATERIAL AND METHODS
This paper is to investigate and Compare the PDC bits
configuration and performance in the 12 ¼” hole section
From Hith till Eva.B (upper part of 12 ¼” section) for one
of the gas fields in South of Iran.
To achieve this approach, we will evaluate and select
the appropriate bit for the related hole section (12 ¼”
section, upper part) first and then the results of
experimental data (bit records) are shown at the second
level.
A. For First Approach (Theorical Approach)
Bits were selected with systematic approach from data
of original wells.
Each selection was evaluated in terms of
lithological characteristics by use of master, Sonic,
Gamma Ray logs when available [3].
Rock Mechanics characteristics, such as porosity,
abrasiveness, hardness, compressive strength,
plasticity were analyzed [2].
We used the mud logging data of another phase
that logs specifications are similar to considered
(papered) phase and import these data to Rock
Strength Analysis Software (ROCKY3.3) for
selecting the PDC bit generally.
Instantaneous ROP, weight on Bit, Speed, Torque
and other drilling parameters from bit records
were correlated with lithology.
Dull bits were analyzed [4]
Mud programs, casing programs and rig systems
were evaluated to improve performance
The analysis technique was effective. Because the bit
design was not altered significantly after the original
wells were drilled.
B. For Second Approach (Experimental Approach)
After selection the appropriate PDC bit, the running
operation was started and bit records were registered. The
characteristics of PDC bit selection are listed below:
Bit size: 12 ¼”, 8 Blade 13mm Cutter
Bit Specification:
Number of Blade: 8, Primary cutter size (mm): 13,
Nozzle Quantity: 8, Junk Slot area (in^2): 30.7, Body
Material: Matrix
Bit size: 12 ¼”, 7 Blade 16mm Cutter
Bit Specification:
Number of Blade: 7, Primary cutter size (mm): 16,
Nozzle Quantity: 7, Junk Slot area (in^2): 35.7, Body
Material: Matrix
At these bit records, various parameters are mentioned
such as Depth in, Depth out, Drilling Meters, Drilling
hours, Rate of Penetration, Drive procedure, Cost per
meter and the related formation.
Cost per Meter, a primary factor in comparing bit
performance in an unconstrained environment, becomes
only an indicator in today's constrained drilling market
[5].
The typical cost-per-Meter formula used to compare
the efficiencies of drilling operations is:
(1)
At the above formula:
During this investigation it was note that rotational
method (i.e., conventional rotary, Positive Displacement
Downhole Motor) had a significant impact on cost per
meter and drilling performance. The frequency and
severity of downhole problems, such as inadvertent pack
offs, stuck pipe and twist offs, tended to be functions of
certain bit/motor combinations. Historical drilling data
were used for optimal pairing of the rotational technique
with the proper bit type to achieve minimal cost per meter
[6] [7].
III. RESULTS
A. Results of First Approach (Theorical Approach)
We entered logging data including sonic data, Gamma
ray and formation density of another phase that similar to
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the planed phase into Rock Strength Analysis software
(Rocky 3.3) and related results were received. The
considered interval depth is based on 1500m–2750m. As
you see at the rock strength analysis report, the UCS
(unconfined strength) of rocks for this interval is
approximately between 17000–28000 psi. For these
quantities of Rock UCS, regard to the bit selection
standards, we should select a PDC bit that appropriate
with hard formations and equal or more than 8 blades
regard to 13mm or 8 mm cutters size. At the next page,
you can mention the UCS, lithology, Sonic data and
Gamma ray diagrams from Depth of 2300m till 2500m
that Max. amount of the UCS are considered at this
interval.
B. Results of Second Approach (Experimental Approach)
For concerned 6 wells (Directional wells), according to
offsets and our analysis, we used 2 types of PDC bits
(item1 and item 2) and the result of bit running operation
is explained and shown at Table I-Table IV (Both bits
have been run with motor (7:8) lob configuration, same
BHA, same hole deviation and drilling parameters):
At starting of section 12 ¼” drilling operation, for one
well from Hith-Eva.b, we use PDC bit (Item 1). The
related record is shown at Table I (dull condition: lost in
Hole, because of BHA failure):
TABLE I. BIT RECORDS OF PDC BIT (8 BLADES,13MM CUTTER WITH
MOTOR ROTATION)
Type S/N Depth
(m) Hrs ROP $/M Inc IN Out
Item 1
(8b13c) A 1675 2817.0 1142 64.3 17.8 579.3 62
For second well from Hith-Eva.B, we used PDC bit
(item 2). The related record is shown at Table II (dull
condition: 5-3-BT-N-X-I-LT-PR):
TABLE II. BIT RECORDS OF PDC BIT (7 BLADES,16MM CUTTER WITH MOTOR ROTATION)
Type S/N Depth
in
Depth
Out Meters Hrs ROP $/M Inc
Item 2
(7b16c)* A 1620 2910 1290 268 4.8 1873.0 52
Regard to the above records, the PDC bit with 8 blade
of 13mm cutter (item1) is better than one (item 2). But
for more investigation about the PDC bit with 7 blade of
16mm cutter, we used new one again for another well and
the below records are mentioned at Table III (dull
condition: 1-3-CT-G-X-1/16-PN-HP):
TABLE III. BIT RECORDS OF PDC BIT (7 BLADES,16MM CUTTER WITH MOTOR ROTATION)
Type S/N Depth
in
Depth
Out Meters Hrs ROP $/M Inc
Item 2 (7b16c)*
B 1646 2546 900 91.8 9.8 1042.0 41
Regard to comparison of the above records, the
performance of the PDC bit (item 1) such as ROP, Cost
per meter are better than performance of PDC bit (item
2).In this reason, for the rest of wells from Hith-Eva. B,
we used PDC bit (Item 1). The records are shown at
Table IV
TABLE IV. BIT RECORDS OF PDC BIT (8 BLADES,13MM CUTTER WITH MOTOR ROTATION)
Type S/N Depth
in
Depth
out M Hrs ROP $/M Inc
Item 1 (8b13c)*
B 1686 3195 1509 124 12.2 775.0 50
Item (8b13c)
1**
C 1635 2915 1280 133 9.6 974.0 54.5
Item
(8b13c) 1***
D 1630 2920 1290 158 8.4 1072.0 52
Dull conditions of above items are explained below [4]:
(*): 4-1-BT-A-X-I-CT,RO-DTF
(**): 3-4-CT-A-X-I-BT-BHA
(***): 6-4-RO-A-X-I-PN,LT-PR
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Journal of Industrial and Intelligent Information Vol. 2, No. 4, December 2014
©2014 Engineering and Technology Publishing
The below Diagrams (Fig. 1) show the brief of above
bit record for 6 various wells with lithology from Hith-
Eva. B (Hole 12 ¼”, Upper section):
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Figure 1. Bit records for 6 various wells at 12 1/4" Hole section (upper part)
IV. DISCUSSION
The destination of this paper is to investigate and
Compare the PDC bit configuration and performance in
the 12 ¼” hole section From Hith till Evaporate B (Top
Section) for one of the gas fields in South of Iran. The
interval is mainly composed of thick white anhydrite beds,
cream to off-white dolomitic streaks and white to off-
white limestone. It was also observed traces of cherts in
the middle and layers of gray claystone throughout the
interval.
This paper has two approaches. The first one is related
to theoretical strategy that related data were calculated by
Rocky 3.3 and the bit design estimation was considered
regard to standard bit design and selection procedure. The
second approach was related to experimental data that we
used 2 types of PDC bits at 6 wells.
At this interval, the optimized one is related to PDC bit
with 8 blades of 13mm cutter size, Nozzle Quantity: 8
and 30.7 square inches Junk Slot Area. The average Cost
per Meter is good amount and Rate of Penetration for this
bit is 12 m/h respectively for drilling 4 various wells.
The results showed that, this bit is a good selection for
drilling the related interval (Upper part of 12 ¼” Section).
These results (theoretical and experimental Data) show
that selection of bit with 8 blades 13mm cutter is more
beneficial than bit with 7 blades 16mm cutter. The cost
per meter is a key factor for comparing two different bit
and it has been approved that the 8 blades 13mm cutter
PDC with the special features such as back cutters is the
most effective selection for this subject.
Now we investigate why this bit is appropriate for this
interval.
This bit type (Item 1) is appropriate for hard and
compact formation with very high compressive strength.
More features of this bit type (item 1) are described
below:
Matrix body with heavy cutter layout density.
Super hard cutter application makes bit capable to
drill high abrasive formation.
Force balanced design ensures less vibration while
drilling.
Special enhanced gauge protection.
Dynamic flow simulating technology is used for
hydraulic design to ensure optimum bottom hole
flow pattern and anti-balling and benefit for
increasing ROP.
Back cutter and back ream cutter features.
V. CONCLUSION
Selection of the optimized bit is the most important
factor to prevent the high Cost per meter and approaching
the long interval drilling and Rate of Penetration (ROP).
The optimized PDC bits in the 12 ¼” Hole section of gas
field for one of the phases in the south of Iran is 8 blades
of 13mm cutter size, Nozzle Quantity: 8 and 30.7 square
inches Junk Slot Area.
ACKNOWLEDGMENT
We are very thankful from Dana Drilling Company for
kindly cooperation.
REFERENCES
[1] H. Motiei, Stratigraphy of Zagros. End Edition Geological Survey
of Iran, Tehran, 2003. [2] P. Rafiee, B. Ziaee, and V. Hassani, Geological Completion report
of South Pars Gas Field. 2012.
[3] Schlumberger. [Online]. Available: www.slb.com [4] IADC Drilling Manual, 2000.
[5] T. B. Martin Jr. and D. McKinnell, Optimization of Bit
Performance for Qatar’s Offshore North Field, 1997. [6] J. V. Venrooy and J. D. Callais, New PDC-Bit Technology Proves
Cost-Effective in Drilling Oman Carbonates, 1997.
[7] V. P. Perrin and G. Mensa-Wilmot, A New Approach to Bit Performance Evaluation, 1997.
Aryan Javanmardian was born on 1986 in
Tehran, Iran that has a Master Science degree of
Mechanical Engineering from Iran University of Science & Technology on 2012. Aryan's major
field is related to the optimization of tools for
drilling operation. He is working at Dana's bit and Down-Hole Company as Senior Optimization
Engineer and he has worked at this company for
approximately 3 years ago. He has 2 Iranian industrial patents ''Patent No. 42998, Self-controlled silencer'', "Patent
No. 46417 , A type of
robot for painting the surfaces of metallic & non-metallic plates''. He is
attending at Iranian Elite Institute and Iranian Inventors Society.
Vahab Hassani was born on 1977 in Shahrood, Iran that has a Master Science degree of Geology from University of Tehran on 2003 while
accepted and graduated as top student. Vahab's major field is related to
the Bit operation and drilling optimization. He is working at Dana's Bit and Down-Hole company as head of bit operation and drilling
optimization and he has worked at this company approximately 5 years
ago while has experienced 6 years as senior optimization & evaluation engineer at ReedHycalog Co. he has one paper " Origin and brine
evolution and evaporate sedimentation in Chah Jam Playa" at 7th
symposium of geology society in Iran 2003" and one translation " surface geochemistry in petroleum exploration, 2002"
Pedram Rafiee was born on 1980 in Shiraz, Iran, that has PHD in
Geology from Islamic Azad University (Science and Research branch, Tehran, Iran). Pedram's major field is related to the geology for drilling
operation. He is working at Dana Drilling Company as senior geologists
of the South Pars Gas fields and he has worked at this company for
approximately 3 years while has experienced 8 years as a geologist at
Statoil, KPE Co.
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Journal of Industrial and Intelligent Information Vol. 2, No. 4, December 2014
©2014 Engineering and Technology Publishing