Well Workover

AKHILOME .E. CHRISTIAN
S/PED/81002
PRODUCTION TECHNOLOGY
By

INTRODUCTION •What is WORK OVER
WORK-OVER
OPERATIONS
•WELL KILLING
•RECOMPLETION
• RE-PERFORATION
• STIMULATION,
• SQUEEZE CEMENTING,
• RETRIEVAL/RUNNING OF TUBING
AND COMPLETION HARDWARE, ETC.
WHY
WORKOVER
CONCLUSION
Reasons for Workover

 After drilling a well, the formation is evaluated to know if it
contains Oil in commercial quantity. If it does, the well is
completed and placed on stream. At a point in the
producing life of the well, the initial conditions of the well
may change leading to a decline in the performance of the
well.
 If the reservoir still contains a reasonable amount of
hydrocarbon something has to be done to improve the
performance of the well or reservoir.
Akhilome Christian - Well Workover

 The term Work-over, is used to refer to a kind of well
intervention that is aimed at enhancing the performance of
a well. It involves recompleting already completed well for
improved performance.
 The process of performing major maintenance or remedial
treatments on an oil or gas well after initial completion . In
many cases, work-over implies the removal and
replacement of the production tubing string after the well
has been killed and a work-over rig has been placed on
location.

 The operations involved in maintenance and servicing,
repairing, installation of down - hole production
equipment etc. in an initially completed well (production
well) is termed as workover operation
 To some degree Workover operations varies depending on
the reasons for which they are carried out. The first basic
operation done during Workover is well killing

 Well killing involves circulating a fluid (called workover fluid e.g.
Brine) into the well whose weight is appropriate to control the
formation pressure.
 The workover begins by removing the well head and possibly the
flowline, then lifting the tubing head from the casing hanger thus
beginning to pull out the tubing from the completion.
 Workover Operations involves Involves well kill operation,
retrieval of tubing and completion hardware, re-perforating,
stimulating, running of completion and wellhead hardware
equipment and tubing

 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

Is it really necessary for us…???

 Workover operations are carried out for mainly two reasons such
as:
Mechanical Problems
Reservoir Related Problems

a) Repair/Replace of
damaged equipment
b) Replace artificial lift
equipments
c) Cement and Casing
Problems
Mechanical Reasons
Reservoir Related Reasons

a) Repair natural damage
within the well
b) Zone Transfer
c) Stimulation
d) Convert well from
production to injection
Mechanical Reasons
Reservoir Related Reasons

 One of the most common reason for a Workover is to recomplete a
well from one zone to another.
 Many wells are drilled to intentionally penetrate many zones, but
only one zone at a time is produced. In some wells, lower zones are
produced first.
 When reservoir depleted, they are recompleted (isolated) so that
another zone farther up can be produced.

 When a reservoir does not have, or cannot maintain, sufficient
drive energy to produce at an economical rate, assistance
through artificial lift is required. There are four basic types of
artificial lift:
 Sucker rod pump
 Hydraulic pump
 Electric submersible pump (ESP).
 Gas lift.

 Stimulation is general term describing variety of operations
performed on a well to improve its productivity.
 It plays a vital role in production operations.
 Production in a damaged or low-producing zone can be
increased by some techniques as follow:
 (i) Acid Stimulation
 (ii) Hydraulic Fracturing

 Workovers are done to
convert producing wells to
injection wells. In this type
of workover water, Gas,
Chemicals etc. can be
injected into the reservoir
 For example, such a
workover might involve
converting a producing well
configured for continuous or
intermittent gas lift as shown
in the figure given on the
right hand side to a water
injection well.

 The profitability of a well as an investment venture depends on how
long it is on stream and on how much it produces. Its lifetime and output
are naturally due to the reservoir's initial characteristics. However, they
are also dependent on keeping the well maintained in good working order
and adapting completion properly to the constantly varying conditions
prevailing in the reservoir and around the wellbore.
 Although proper drilling, cementing, and completion practices
minimize the need, virtually every well may need several workovers
during its lifetime to satisfactorily fulfil its purpose.

Well Workover

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