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WORK OVER OPERATION
The operations involved in maintenance and servicing, repairing, installation of down - hole production equipment etc in a cased hole / production well is termed as work-over operation
Rig Selection
Mobile work - over rig is used for this purpose. The rig is selected on the basis of total expected load to be handled
Rig in Operation in OIL
Presently OIL has 13 nos. of in house work – over rigs
In addition 2 nos. of Chartered Hired work over rigs are in operation.
Details of Mobile Work over rig
SL.
NO
OUTFIT Rated Horse Power Date of
commissioning Mast Height
Work over
Depth, 2 7/8"
OD Tbg
Drilling Depth,
4 1/2" OD Drill Pipe
1 BHEL - B 235 HP, MEDIUM DUTY 25/06/1988 102 ft 4572 M 1830 M
2 BHEL - C 235 HP, MEDIUM DUTY 15/03/1989 102 ft 4572 M 1830 M
3 BHEL- D 235 HP, MEDIUM DUTY 31/03/1989 102 ft 4572 M 1830 M
4 CARDWELL - B 250 HP, MEDIUM DUTY 20/10/1983 96 ft 4875 M 1830 M
5 CARDWELL - C 250 HP, MEDIUM DUTY 28/09/1983 96 ft 4875 M 1830 M
6 CARDWELL- K - 600 400 HP, HEAVY DUTY 10/6/1985 112 ft 7315 M 3000 M
7 KREMCO K- 600 250 HP, MEDIUM DUTY 18/02/1986 96 ft 3658 M 2000 M
8 SKYTOP - B 250 HP, MEDIUM DUTY 4/4/1978 95 ft 5185 M 2286 M
9 RG - 600 - A 600HP, HEAVY DUTY 21/02/2009 115 ft 6000 M 2500 M
10 RG - 600 - B 600HP, HEAVY DUTY 6/11/2008 115 ft 6000 M 2500 M
11 RG - 600 - C 600HP, HEAVY DUTY 25/11/2008 115 ft 6000 M 2500 M
12 RG - 600 - D 600HP, HEAVY DUTY 14/12/2008 115 ft 6000 M 2500 M
13 RG - 600 - E 600HP, HEAVY DUTY 7/10/2009 115 ft 6000 M 2500 M
14 ZJ - 20 (CH) 600HP, HEAVY DUTY 14/04/2008 115 ft 6096 M 2500 M
15 ZJ – 30 (CH) 750HP, HEAVY DUTY 23/02/2008 124 ft 7000 M 3000 M
Reasons for Work-over
To prevent water coning
To prevent excessive gas production in an oil well
To enhance production
To control sand problems
Re-completing a new zone / reservoir
Completing in multiple reservoir
Down hole Equipment & Cement repair
Contd…
Reasons for Work-over
To eliminate excessive water or gas production
To repair mechanical failure down hole equipments
To gain additional production through re-completion
To evaluate potentially productive zones
To clean scaling of Tubing & Casing
To clean perforation plugging
To replace production string
Contd…
Reasons for Work over
To control sand entering well bore from formation
To increase formation permeability
To install artificial lift system, bottom hole pump etc.
To repair or replace well head
Conversion of well
Work -over Operations
Re-perforation or extention of perforation
Plug back and perforation higher up
Isolation Repair
Acidization
Cleaning of production string
Gravel pack
Casing repair and recovery
Contd…
Work over operations
Milling Bridge Plug, Drilling Cement Plug
Fishing
Sand cleaning
Well head repair or replacement
Installation of artificial lift system, bottom hole heater etc.
Cleaning of perforation, scaling in casing & tubing
Work over operations
Conversion of low producing well to water injection for increasing reservoir pressure.
Conversion of dead well to water disposal well for pumping back formation water producing along with oil
Steps in Work-over Operation Well Selection
Work-over Policy Preparation
Site Preparation
Security Deployment
Static and Outfit mobilization & placement
Work-over fluid preparation / collection
Well killing
Operations as per well plan
Contd…
Steps in Work-over Operation Rig-up Mast
Well killing
Rig down of X-mass tree & rig up of BOP
Circulation
Tripping of Tubing
Specified jobs
Final Running in of Tubing
Rig down BOP
Contd...
Steps in Work-over Operation
Rig up X-mass tree
Enliven the well and hand over to Production Department.
Rig down Mast
Mobilize the Rig to new location as per plan
Precautions during Rig-up & Rig- Down
All loose parts and tools shall be securely fastened.
High pr circulating fluid lines shall be securely bolted down
During R/downing the well head shall be protected against damage from sliding or falling object.
The raising and installation of heavy load shall be done during daylight hours unless adequate general lighting arrangements are provided at the place of work.
Common Terms in Drilling & Work-Over rigs
Derrick Platforms & floors Crown Block & Traveling Block Ladders & Guardrails & covers Emergency escape device Weight Indicator Safety belts Draw-works Cathead & cat line Tongs Casing lines
MAIN EQUIPMENTS ARE
W/O RIG including mast & substructure
R / Table & Hoisting Equipments
Static including pumps, tanks, bunkhouses
Precautions against Blowout
BOP & Controlling Unit
Well Control
Fire fighting equipments
Fencing & well security
Safety Requirements
An area within 30 m of the well should be danger zone. All electrical equipments should be de - energized in case of emergency.
Adequate arrangements for fire fighting should be provided & portable fire extinguishers are available at different places. Crew must be well conversant with the use of fire extinguishers / fire pump
GENERAL PRECAUTIONS A standard railings should guard every
open sided D/Floor & D/board
Rig should be provided with ladder arrangements.
Emergency escape device & Fall prevention device should be incorporated.
To use Personal protection equipment (PPE) by every crew personnel.
GENERAL PRECAUTIONS The well head should be well protected
against falling objects
The D/Floor should be reasonably clean of oil, mud ,so as to prevent from slipping.
Floor saver and crown saver must be checked every day.
F/brake & Hydrometric brake system should be working condition always.
Casing line inspection must be carried out.
Safety Practice At the beginning of every shift the
instruments and controls at driller’s console, D/W’s, pumps, casing line, catline & BOP shall be examined by the SDE & he shall satisfy himself that these are in good working order
No person remains in position of danger at or near the rotary table during operation.