Breakthrough horizontal well drilling performance in hard abrasive sandstones by turbo-drilling in potassium formate brine

1. Breakthrough Horizontal Drilling
Performance in Pre-Khuff Strata with
Steerable Turbines
Mike Simpson, Shaohua Zhou, Dave Treece, Carlos Rondon,
Tom Emmons, Saudi Aramco; Craig Martin Sii-Neyrfor and
Mohammad Tahir, Diamant Drilling Services
SPE 90376

2. Outline
Introduction
Economic Importance of Pre-
Khuff Reservoirs
Pre-Khuff Geology
Turbo-drilling Experience in
Saudi Arabia
Breakthrough Horizontal Drilling
Performance
Turbo-drill Runs in Potassium
Formate Brines
Conclusions

3. Introduction
Saudi Aramco Produces 8.1 mmbopd, 6.9
bscfd non-associated Gas &1 mmbpd NGL’s

4. Introduction
It operates 49 Land
and Offshore Drilling
& Workover Rigs
consisting of:
25 Onshore Oil Rigs
3 Offshore Oil Rigs
21 Land Gas Rigs,
2000 hp or larger

5. Economic Importance of
Pre-Khuff Reservoirs
25% Gas Prod. f/Pre-Khuff – Mostly Unzy
Unzy’s Most Abrasive & Problematic to Drill
Gas Demand will inc. to 12 bscfd by 2025
50-55% of this must come from the Pre-Khuff
Currently Drlg. 47 Gas Wells/year w/18 Rigs
Utilizes three Workover Rigs & one Snub. U.
Unzy Well Design Changed to Horz. in 2003
to meet demand

6. Pre-Khuff Geology
Pre-Khuff – Formations of Lower
Permian Age or older deposited before
the Khuff
Include the Unayzah, Jauf, Tawil,
Sharawra, Qusaiba, Sarah, Qasim and
Saq
Mainly hard and ultra abrasive
sandstones interbedded with siltstones
and shales
Shales often unstable requiring 1500
psi overbalance to mitigate tight hole

7. Unayzah A, B & C
Unzy-A has 3000
to 9000 psi UCS
(PDC Drillable)
Unzy-B (7000-
27,000 on this RMA)
Too hard & Abrasive
for PDC’s – TCI’s &
Impregs Only
Unzy-C 9000-
22,000 UCS

8. Unayzah-A Core from Tinat-6
•Abrasive
• Not as
Hard as
UNZY-B
•Friable

9. Internal friction angle (phi): Unayzah reservoir core rock mechanics lab test result
40
45
50
55
60
65
0 2 4 6 8 10 12 14
porosity (%)
internalfrictionangle(deg)
phi (WDYH-1)
phi (GHZL-2)
phi (GHZL-3)
Unayzah Porosity vs. Abrasivity from Offset Core
Unayzah Angle
of Internal
Friction typically
ranges between
42 and 63° for the
A, B and C.

10. BHA: 3 BHA TYPE : Vertical
DATE: WELL : TINAT #3
JOB N° : RIG: SF 162 ARAMCO
GRAPHIC DESCRIPTION OD (in) ID (in) LENGTH ( ft )SERIAL N°
8 3/8"
Hughes Christensen S279G8-3/8" -- 1.17 1.17)
CUSTOMER :
15 x HWDP
2 x Drill Collars
5" 3" 452.41970.82 ARAMCO
Jars
6-1/2" 59.45 518.41 ARAMCO
Cross-Over 6-1/2” 1.49 458.96 ARAMCO
Flex Joint 457.47 ARAMCO
12 x Drill Collars
6-1/2” 1.50 426.81 ARAMCO
6-1/2"
2-13/16"367.27425.31 ARAMCO
Roller Reamer 6-1/2" 2-7/8" 6.30 58.04 ARAMCO8 3/8"
Circulating Sub 2 " 1.80 51.74 ARAMCO
Turbine Section 1 6-5/8" -- 17.61 49.94
Turbine Section 2 -- 16.96 32.33
8-516"
Turbine Bearing Section6-5/8" 12.40 15.37
Bit-Box-Stabilizer 3" 0.95 2.12 NEYRFOR
64010
6-5/8"
6-1/2"
Cross-Over 2-13/16"
66039
66042
2-13/16"15.33
8-516"
ARAMCO442.14
6-1/2"2-13/16"15.33
2-13/16"
2-13/16"
BIT-STUCK BHA: TINAT #3
8/30/97
--
Bearing Shaft
(Box-End)
6-1/2"
6-5/8"
--
-- 0.85 2.97 NEYRFOR
The 1st
Vertical Turbo-drill run was
made with a Two Stage conventional
turbine and Imprenated diamond Bit
from 16,143 to 16,149’.
Attempted to pick up off bottom for
connection, bit stuck on bottom on
8/30/97.
Back-reamed and jarred fish up to
16,144’.
Spotted Diesel, Pipe-Lax and 15% HCl,
No Success.
Finally string-shot/backed off @ 14,674’
& again @ 15,736’ leaving 430’ of fish
(Bit / turbine / CS / NBRR / 12 DC’s) in
hole.
Lost time: 12 days
Stuck Pipe/Fishing Cost: $560,000
Turbo-drilling Experience in Saudi Arabia – 1st
Run
Drilling Report

11. BHA: 2 BHA TYPE:Vertical
DATE: WELL :
JOB N° : RIG:NAD-117 ARAMCO
GRAPHIC DESCRIPTIONOD (in)ID (in)LENGTH ( ft )SERIAL N°
CUSTOMER :
9/21/97 QTIF-150
BIT-STUCK
BHA: QATIF
#150
15 HWDP 3-1/2"2-1/16"458.84980.22ARAMCO
Jars
4-3/4"2-1/4"62.43521.388ARAMCO2 x Drill Collars
12 x Drill Collars4-3/4"2-1/4"
28.36458.59ARAMCO
Roller Reamer 4-3/4”2-1/4"5.2956.10ARAMCO5-7/8"
Cross-Over 2 1/4"1.0750.81ARAMCO
5-13/16"Turbine Section 14-3/4"-- 18.2149.7446114
5-13/16"Turbine Section 24-3/4"-- 17.3231.5346115
5-13/16"Turbine Bearing Section4-3/4"-- 12.21514.212
(Box-End)
Bearing Shaft
0.78 2.00
5 7/8"-- 1.22 1.225-7/8” Impreg
Bit (Pin-Up
4-3/4"
4-3/4"
374.49 ARAMCO430.59
4-3/4"2-1/4"
--
Drilled 5-7/8” Hole with T-2 Turbine and 5-7/8” STC-
K35TX Impreg Bit from 16,135 to 16,147’ (12’).
Picked up to make connection and stuck pipe 7’ off
bottom on 9/20/97.
Spotted 40 bbl Grease pill - jarred and worked on
pipe, no success.
Spotted 1100 gal of HF acid & two 40 bbl EZ-Spot
Pills & Worked pipe.
String Shot Backed off @ 15,866’ leaving 274’ of
fish (7 DC, NBR, XO, Turbine & Bit) in hole.
Worked on fish a total of 11 days then decided to
ST.
Spent another 13 days sidetracking back to 16,147’.
Total Time lost: 23 days
Total Stuck Pipe/Fishing Cost: $690,000
Turbo-drilling Experience in Saudi Arabia - 2nd
Run
Drilling Report

12. BHA: 2 BHA
TYPE:
Vertical
DATE: WELL:
JOB N° : RIG:SF 174 ARAMCO
GRAPHICDESCRIPTIONOD (in)ID (in)LENGTH ( ft )SERIAL N°
32 x 3-1/2" HWDP3-1/2"2-1/16"986.671549.9ARAMCO
3 x Spiral Drill Collars4-3/4"2-1/4"92.94563.22ARAMCO
Jars 4-3/4"2-1/4"31.35470.28ARAMCO
10 x Spiral Drill Collars4-3/4"2-1/4"310.73438.93ARAMCO
5-13/16"String Stabilizer-- 2-1/4"5.76128.20ARAMCO
2 x Spiral Drill Collars4-3/4"2-1/4"62.18122.44ARAMCO
Bit Sub w/Float Valve4-3/4"2" 3.1560.26ARAMCO
Cross Over Double Pin.4-1/2"1-3/8"1.4457.11ARAMCO
5-13/16"String Stabilizer-- 2-1/4"5.7755.67ARAMCO
5-13/16"Turbine Section 14-3/4"-- 18.2049.9046143
5-13/16"Turbine Section 24-3/4"-- 17.3031.7046122
5-13/16"Turbine Bearing Section4-3/4"-- 12.1914.40
Bearing Shaft (Pin-End)
Safety Sub 5" 1-3/16"0.901.90
5-7/8"-- 1.001.00
5-7/8” Impreg bit (Box-Up / T.F.A: =1.00in²)
CUSTOMER:
BIT STUCK –
HRDH-642
HRDH-64212/28/99
4-3/4"-- 0.312.21
Drilled 5-7/8” Hole with T-2 Turbine and 5-7/8”
STC-KGRCETPX Impreg Bit from 13,975 to
14,057’ in the Unayzah-B. Picked up to check
9’ Drilling Break f/5-25 fph – Pipe Stuck.
Spotted 50 bbl Hi-Vis and Grease pills & jarred
with 25K, no success.
Jarred out of Neyrfor Bit Safety Sub with 60K.
Left bottom half of Safety Sub and Impreg bit
on bottom (1.57’).
Milled and worked on fish with 5-7/8” Burn
shoes, Cobra Mills, Taper Taps and Jars for 21
days and finally broke through.
Total Time lost: 23 days
Total Stuck Pipe/Fishing Cost: $842,000
Turbo-drilling Experience in Saudi Arabia - 3rd Run
Drilling Report

13. Primary Cause of Bit Sticking
Radial Hole Deformation
Radial Hole Deformation and breakout in the
near wellbore region due to High Insitu
Stresses
Equivalent to 1/16” in 8-3/8” hole and 1/32” in
5-7/8” hole

14. Radial Hole Deformation
Excessive Breakouts
normally occurred
across Sandstones,
as shown in this
Image Log from
HWYH-950

15. Secondary Cause of Bit Sticking
– Unstabilized Rotating Length
Bit Box
Stab
Pin Up Bit Box Down Shaft Lower Brg Stab Turbine Body
2.97 ft
2.00 ft
Turbine BodyLower Brg StabBox Down ShaftPin Up Bit
2.21 ft
Turbine BodyLower Brg Stab
Pin Down Shaft
Box Up Bit
TINAT-3
8 3/8”
Bit Sticking
QATIF 150
5 7/8”
Bit Sticking
Haradh 642
5 7/8”
Bit Sticking
Bit Safety Sub
1.43
Box Up Bit Pin Down Shaft Lower Brg Stab Turbine Body
HWYH 961
8 3/8”
NO Bit Sticking

16. Turbo-drilling Experience in Saudi Arabia – 4th Run
4th
Vertical Run on HWHY-961:
8-3/8” IADC M842 Impreg bit
with Box-up Connection
Turbine Sleeve with Back-
reaming Feature
Prismatic Link Release
Mechanism (120,000 lbf)

17. Turbo-drilling Experience in Saudi Arabia – 4th Run
Run on HWYH-961
Made 242’ in 23.5
hrs @ 10.3 fph with
cost of $443/ft

18. Figure 11: Caliper Log over Turbo-Drilled Interval (100 pcf MW)
(No undergauge hole across Unayzah or Jauf)
7.250
7.625
8.000
8.375
8.750
9.125
9.500
9.875
10.250
10.625
11.000
11.375
11.750
12.125
12.500
13690
13700
13710
13720
13730
13740
13750
13760
13770
13780
13790
13800
13810
13820
13830
13840
13850
13860
13870
13880
13890
13900
13910
13920
13930
13940
Depth (feet)
Caliper(inches)
0
20
40
60
80
100
120
140
GR(api)
CALX (in)
CALY (in)
GR (api)
Khuf f -D
Anhydr i te
Unayzah Jauf
HWYH-961 – No Undergauge hole across Unayzah or Jauf
Fourth Turbodrill Run – No Undergauge hole

19. Horizontal Vs. Vertical Well Productivity
Horizontal Wells
showed substantial
increase in
productivity over
Vertical Wells
without Fracking
GHZL-3
GHZL-8
G
HZL-4
GHZL-11(H)
GHZL-10 GHZL-5
GHZL-7(H)
GHZL-2
GHZL-9(DL)
GHZL-6(H)
GHZL-1

20. Unayzah even tougher to drill horizontally
Diminished bit performance in 5-7/8” vs. 8-
3/8” bits
Diminished bit performance in Horizontal vs.
Vertical Hole
Requirement that all bit runs be made on
PDM’s at much higher RPM’s than on rotary
Diminished bit performance in the target
reservoir - the Unayzah-B

21. Abrasive Wear/Lost Cones – PDC/Impreg Wear
Major Problems in Unayzah-B
Two 5-7/8” IADC 627Y TCI’s lost all three cones while
drilling Unayzah-B on WDHY-1
HSE concern over tripping frequency with TCI’s (every
14 hrs) in desert climate with daytime temp ≥120°F

22. Lost Cones – PDC/Impreg Wear
Major Problems in Unayzah-B
RR Impreg 100%
Worn after drilling
22’ in 8.5 hours
Run on Low-Speed
PDM
ROP: 2.6 fph
WOB: 13,000 lbf
RPM: 190
Dull: 8-8-RO-G-X1/16

23. Lost Cones – PDC/Impreg Wear
Major Problems in Unayzah Formation
PDC completely
cored out after
Drilling 219’ in 26.5
hours
Run on Low-Speed
PDM
ROP: 8.2 fph
WOB: 18,000 lbf
RPM: 240
Dull: 8-7-RO-M-X-IN-
CR&BT-PR&DMF

24. Horizontal Solution to Radial Hole Deformation
Drill Paralell to Maximum Horz. Stress Axis
Horizontal Wellbore Drilled Due East or West in Ghawar Area
(Parallel to Shmax)
•Shmax
Shmax
Shmax
Vertical Well
Hole diameter reduction causing ”bit sticking”
Slight Hole diameter
enlargement providing
stable hole & drilling
conditions “no sticking”
Shmax

25. Solution to hole spiraling – One Stage 4-3/4”
Steerable Turbine & Box-Up bit (Min. Rot. Length)
One Power
Section
99 Pressure Profile
Turbine Blade
Sections
Flexible Titanium
Drive Shaft with1°
integral bend
Use of Box-up bit
with Turbine-Sleeve

26. Breakthrough Horizontal Drilling
Performance on WDHY-1
1st Horizontal Run:
5-7/8” IADC M842
Box-up 12 blade
Impregnated diamond
bit run on advanced
steerable turbodrill
Drilled 737’ averaging
5.5 fph in 134 rotating
hours with cost of
$402/ft. Graded 3-3-
WT-A-X-I

27. Breakthrough Horizontal Drilling
Performance on WDHY-1
2nd
Horizontal Run:
5-7/8” IADC M842
Box-up 12 blade
Impregnated diamond
bit run on advanced
steerable turbodrill,
drilled 852’ averaging
7.0 fph in 122 rotating
hours with cost of
$330/ft. Graded 3-3-
WT-A-X-I

28. Turbo-drill Operating Parameters
WDYH-1(re): turbine drilling parameters (SA5.4)
0
5
10
15
20
25
30
35
40
15850
15900
15950
16000
16050
16100
16150
16200
16250
16300
16350
16400
16450
16500
16550
16600
16650
16700
16750
measured depth, ft
ROP/WOB/CircMnt
0
500
1000
1500
2000
2500
3000
3500
4000
RPM/GPM/PSI
Circ Mnt
aver WOB
ROP FT/HR
turbine RPM
Press PSI
Flow GPM
WOB: 4,000 lbf
RPM: 1,400
ROP: 7.0 fph
P. Press: 2900 psi
Circ. Rate: 220 gpm

29. Breakthrough Horizontal Drilling
Performance on WDHY-1
100 200 300 400 500 600 700 800 900
SA5.2 WDYH-4
XR40YODPD
WDYH-4
KRG50CETPXX
WDYH-1
SA5.4 WDYH-1
FOOTAGE DRILLED
TURBINE
TURBINE
PDM
PDM
FORMATION
DRILLED
Unayzah –B –
Siltstone/ Sandstone
100 200 300 400 500 600 700 800 900
SA5.2 WDYH-4
XR40YODPD
WDYH-4
KRG50CETPXX
WDYH-1
SA5.4 WDYH-1
FOOTAGE DRILLED
TURBINE
TURBINE
PDM
PDM
FORMATION
DRILLED
Unayzah –B –
Siltstone/ Sandstone

30. Breakthrough Horizontal Drilling
Performance on WDHY-1
14000
14500
15000
15500
16000
16500
17000
17500
MD(Feet)
8/3/2003 8/10/2003 8/17/2003 8/24/2003 8/31/2003 9/7/2003 9/14/2003
WDYH-1 first lateral, 5-7/8" bit record
SA5.4
KRG50OETPXX
MILL
XTG48PX
SL63DGKPR
XSD57D
DSX143D
XR40YOD
R4
Impreg/Turbine
Runs
58% of Total
Footage

31. AVERAGE 5-7/8" BIT PERFORMANCE IN
UNAYZAH-B For WDHY-1 & 4
BIT TYPE # RUN
Average
FOOTAGE
Average
HOURS
Avg.
ROP
Avg.
$/FT
DULL GRADE
T- B
TSP/PDM 1 13 7 1.9 4608 3---3
IMPREG/PDM 7 82 23 3.6 2219 8---8
IMPREG/TURB 2 794 128 6.2 366 3---3
PDC/PDM 14 152 28 5.5 1233 6---5
TCI/PDM 49 124 12 10.6 545 5---8
TSP/PDM
IMPREG/PDM
IMPREG/TURB.
PDC/PDM
TCI/PDM
4608
13
2219
82
366
794
1233
152
545
124
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
FootageCost,$/FT
$/FT FOOTAGE

32. Turbo-drill Runs in Potassium Formate Brines
Clear “solids free” Liquid the can be used as
drilling, spotting, workover or completion fluids
Sodium Formate – up to 85 pcf
Potassium Formate up to 98 pcf
Cesium Formate up to 144 pcf
Used in over 400 wells since introduced by
Shell in 1993
Extends Temperature Range of Conventional
Viscosifiers and Fluid Loss Agents from 240-
340º F. Cesium Formate successful up to 429°F

33. Turbo-drill Runs in Potassium Formate Brines
3rd
Horizontal Run:
5-7/8” IADC M842
12 Blade Impreg run
on 4-3/4” Turbine in
Unzy-B on HRDH-
658
Suffered Total
Failure of Impreg
Segment Cutting
Structure

34. Turbo-drill Runs in Potassium Formate Brines
4th
Horizontal Run: 5-
7/8” IADC M842 8
Blade Impreg run on
4-3/4” Turbine in
Unzy-B on HRDH-
658
Drilled 81’ in 24.5
hrs at 3.31 fph in 93
pcf K-Formate Brine
Drilling Fluid

35. Turbo-drill Runs in Potassium Formate Brines
5th
Horizontal Run:
5-7/8” IADC M842
12 Blade Impreg run
on 4-3/4” Turbine in
Unzy-B on HRDH-
658
Drilled 60’ in 16 hrs
at 3.75 fph in 102
pcf K-Formate Brine
Drilling Fluid

36. Effect of Overbalance of Rock Confined
Compressive Strength
Increased overbalance between formation and Drilling fluid
increase confined compressive strength and impede drilling rates
18000
20000
22000
24000
26000
28000
30000
32000
34000
36000
0 100 200 300 400 500 600 700 800 900 1000 1100 1200
confined pressure (overbalance) in psi
rockcompressivestrength(psi)
φ = 40
o
φ = 45
o
φ = 50
o
φ = 55
o
φ = 60
o

37. Potassium Formate Brine Performance HRDH-658
Use of a 102 pcf potassium Formate Brine
with excess CaCO3 on HRDH-658:
Lowered Pump Pressures
Decreased Rotating Torque and Drag
Allowed a 11,649’ horizontal section to be
drilled with 1500 psi overbalance without
differentially sticking the drillstring

38. Turbo-drill Run in 90 pcf K-Formate Brine on Tinat-3
4-3/4” Steerable Turbo-drill prior to being RIH on Tinat-3

39. Setting Turbo-drill bearing section in Mouse-hole

40. Stabbing Power Section onto Bearing
Section & Making up same

41. Making up Turbine Sleeve Impreg Bit and
checking bearing gap on Turbo-drill

42. RIH with Turbo-drill Assembly

43. Record Breaking ROP run in
Tinat-3 Unayzah-A
6th
Horizontal Run:
5-7/8” M834 Impreg
drilled 360’ in 50 hrs
@ 7.2 fph with avg
cost of $402/ft.
Graded 3-4-WT-A-X-I
Run in 90 pcf
Sodium/Potassium
Formate drilling fluid

44. Average 5-7/8" Bit Performance on Tinat-3
in the Unayzah-A
BIT TYPE # RUN
Average
FOOTAGE
Average
HOURS
Avg.
ROP
Avg.
$/FT
DULL GRADE
T- B
IMPREG/TURB 1 360 50 7.2 410 1---0
PDC/PDM 3 320 35 9.3 320 5---5
TCI/PDM 2 118 13 8.9 472 2---1
IMPREG/TURB.
PDC/PDM
TCI/PDM
410
360
320 320
472
118
0
100
200
300
400
500
AverageDrillingCost,
$/FT
$/FT
FOOTAGE

45. Potassium Formate Brine Performance in Tinat-3
Lowered Pump
Pressures from
4200 to 3400 psi at
220 gpm
Decreased Rotating
Torque from 9400 to
7600 ft-lb
Reduced hole drag
from 25,000 to
10,000 lbf at the end
of the horizontal
section

46. Composition of formate-based drilling fluid
Component Function Concentration
Formate brine Density control
Lubricity
Polymer protection
Biocide
1 bbl
Xanthan Rheology control
Drag reducer
1 ppb
Modified starch
and/or ULV PAC
Fluid loss control 4 –8 ppb
Sized calcium
carbonate
Bridging agent 20 ppb
Potassium
carbonate
pH and corrosion
control
2 ppb

47. Typical properties of formate-based drilling fluid
Property Initial Hot rolling
@285o
F
Mud density (pcf) 90 90
PV (cp) 24 30
YP (lb/100 ft2
) 22 29
Gel (lb/100 ft2
) 4/5 7/9
API Filtrate (cc/30
min)
2.4 1.8
HTHP fluid loss
(cc/30 min) @ 285o
F
13.6 12
ph 10.5 11

48. Solids Control System for K-Formate Brine
Two Decanting Centrifuges
Two Linear Motion Shale Shakers
w/180 & 200 Mesh Screens
Total Solids Content ~ 5%
Drill Solids ~ 0.45%

49. Potassium Formate Brine Liquor in Individual
Bulk Containers (IBC’s)

50. Potassium Formate Powder in 25 kg sacks

51. Poor-Boy Brine Recovery System
Drain Lines
from Rig Floor
Brine collected in
IBC’s for Reuse

52. Expandable Sand Screen Completion
Well Completed with 1410’ of 4”/230 micron
expandable Sand Screens
Run and expanded without major problems.
1
Successful Installation of 1410 ft of
Expandable Sand Screens in TINT-3
7" Liner, 32 ppf
@ 15191 ft MD
9-5/8" Casing, 58.4 ppf
7" Liner
Reservoir top
Running
4" ETC, 230 micron, 5-½" 15.5#
Vam FJL Box x 4" ESS Pin
4" ESS 230 micron, 38ft, 4"
ESS Box x Pin
Sand Control
Circulating Valve,
4-½" Stub Acme
Box Up
4" EBC, 230 micron, 4" ESS
Box x 4-½" Stub Acme Pin
6' EXY Tieback PBR, 5.625" OD 8TPI S.Acme
Threaded Down
7" x 5-½" EXP Deployment Hanger/Packer
5.625" OD 8TPI S.Acme Thread Up x 5-½" 15.5 lb/
ft Vam FJL Pin Down
M. Depth of 7" Liner Shoe : 15191 ft
M.Depth/Length of 5-7/8" O.H. : 16747 ft
Total Length of O.H. : 1556 ft
5-7/8" O.H. Max Inclination : 84.5 deg
Mud : 90 pcf (Na/K/Formate)
Total ESS Run Length : 1410 ft (37Jnts)
Top EXP @
14482 ft
5-7/8" hole, TD
@ 16747 ft
ESS Screen
bottom at 1606 ft
(131 ft from TD)
7" Liner
Hanger top @ 14181 ft
@ 14711 ft
Hanger top @ 13465 ft
Bridge Plug top @ 14014 ft
Whipstock top @ 13990 ft
7" Liner Shoe
@ 15698 ft

53. Conclusions
Steerable turbo-drill/Impreg bit drilling has
emerged as the most cost effective and HSE
friendly manner to drill the Unayzah-B
formation if the well can be drilled parallel to
the maximum horizontal stress axis.
Trajectory control was improved with
consistent reactive torque of 30-35° and a
build rate of 0.3°/100’ in the rotating mode.

54. Conclusions, cont.
IADC 627-737 TCI bits are also cost effective
when total revolutions are maintained in the
150,000 to 175,000 total revolutions range.
PDM/PDC drilling appears to be the
cheapest way to drill the lower compressive
strength Unayzah-A horizontally in the Tinat
Area.

55. Conclusions, cont.
The 90 & 102 pcf potassium formate brines
used in Tinat-3 & HRDH-658 provided lower
pump pressures, torque and drag values and
better bit performance than previously
observed with conventional water base
drilling fluids.
In HRDH-658 the 102 pcf K-Formate Brine
allowed a 1649’ quasi-horizontal section to
be drilled with 1500 psi overbalance without
differential sticking.

56. Conclusions, cont.
Plans are to use Impreg/Turbo-drill
assemblies over the entire Unayzah build
and horizontal sections in conjunction with
K-formate brines to further access their
applicability and cost savings potential.

57. Breakthrough Horizontal Drilling
Performance in Pre-Khuff Strata with
Steerable Turbines
Thank You!
Questions?
SPE 90376