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Slim logs and TLC
Presentation · June 2018
DOI: 10.13140/RG.2.2.19976.88323
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Hussein Almalikee
Basrah Oil Company
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SLIM wells
Wells can now be safely and effectively drilled or sidetracked, evaluated and
completed in small diameters down to 4 1/8". The resulting slim wells can
provide a total well cost reduction of 30%. At the same time, crew exposure,
location size, cuttings and waste mud volumes are drastically reduced.
Production rates of up to 50 MMscf/d (1.4 MMm3/d) gas or 4000 b/d (640
m3/d) oil are achievable in many cases through 3 1/2" liner in 4 1/8" hole.
A key element of slim wells is the monobore completion concept, which is a
completion featuring full-bore access across the pay zone without diameter
restrictions.
Slim hole advantages
Slim hole drilling ensures lower costs of:
• day rate
• wellhead
• casing
• mud products
• location preparation
• logistics
• manpower
• waste disposal.
Slim hole drilling also results in substantial HSE benefits:
• Smaller location and camp
• Smaller crew reduces exposure
• Less logistic support required
• 40-70% reduction in cuttings and waste mud.
Potential disadvantages
• High equivalent circulating densities (ECD) can limit mud
weight
• Limit petrophysical information obtained
• Limit completion options
• Limit production rates
• Limit potential for future sidetrack options
• Early concerns about the robustness of well control
procedures originally proposed for continuous coring have
now been resolved in the light of field experience with
improved computer-based kick detection system (KDS) and
minor modifications to traditional well killing procedures.
Safety of personnel
• Smaller wells mean smaller individual items of equipment and
tubular and a smaller total amount of material to be handled,
which reduces the total exposure of personnel.
• Smaller rigs require smaller crews, and are easier to
mechanise/automate than bigger rigs because the range of
tubular size to be handled is smaller.
• They thus have the potential, in the longer term, of reducing
total exposure even further, though consideration must also
be given to the smaller dimensions of the workspace
available.
Slim Logging
Some Wells are Tough to Log

Complex Well Geometries
– S / J Shaped Wells
– Extended Reach Horizontals
– Re-entry into Slimmer holes

Innovative Drilling Techniques
– Pressurized Mud Cap Drilling
– Under-balance Drilling
– Air/foam drilling
Large
Washouts/
Ledges
Hole
Caving/
Swelling
Shales
Key Seating
Differential
Sticking
Some Wells are Tough to Log
The Solution: Slim Logging
•
2 ¼ inch (57 mm) OD, 302 F (150 C)
continuous working rating , 15,000 psi
•
Operates on wireline or memory
•
Flexible and reliable Conveyance
•
Fully combinable tools
•
Short Tool Lengths, Low Tool Weights
•
Small footprint: ideal for land and offshore
TLC Systems
• TLC - Tough Logging Conditions Tools:
A method of conveyance utilizing the drillpipe to push logging
tools through well bores which are deviated/horizontal or
otherwise difficult to log using conventional methods
(Wireline)
• Types of TLC systems:
1. Standard
2. Slim
Standard TLC
TLC equipment and logging tools are
assembled in the wellbore with drillpipe
slips set around the DWCH.
The PWCH is inserted into the DWCH
and an electrical latch is checked. Once
this is confirmed, the tools are powered
up once again to insure all tools are
functioning correctly.
The electrical latch is checked to give the
logging engineer line readings for
comparison when the actual latch is
made downhole.
PWCH Pump-Down Wet Connect Head
DWCH Downhole Wet Connect Head
Through Drillpipe Conveyance
SLIM TLC
The weight of drill pipe can be used to
force through or past hole
obstructions. Such obstructions could
include ledges, areas that are swelling
or sloughing, areas with filtercake
buildup and more. Once the drill pipe
forces its way past the obstruction(s),
UltraSlim logging tools can then slide
past them insidethe drill pipe
Slim hole continuous coring
The continuous coring method is the utilisation of modified small mining
(or other) rigs capable of continuous coring using wireline retrievable core
barrels, coupled with on-site evaluation of the cores
• The quantity and quality of information that could be
obtained through coring in a series of cheap,
"throwaway" wells, could lead to exploration strategies
involving the close integration of drilling into the
information and evaluation stages
• Continuous coring can accelerate the building of a
geological model which may assist with quantification of
the prospect and in identifying the potential scope
Potential disadvantages
• The surface and subsurface drilling equipment and techniques have been
optimised for mineral exploration drilling in hard rock. This can lead to
problems in, well control, shutting in on false kicks, drilling in active shales,
slow penetration rates, stuckpipe, drillstring vibration failure, certification
and explosion proofing of electrical equipment, etc.
• Coring still has to be terminated when high overpressures are
encountered due to the limitations of the mud systems being used.
Continuous coring has a maximum proven depth of about 3000 metres.
• Coring is slower than destructive drilling because the core needs to be
recovered by wireline at intervals.
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