TO: ENGR SIR HABIB U ZAMAN MEMON

FROM: MUHAMMAD HANIF CHACHAR

(12PG142)

TOPIC: WORKOVER JOBS

What is “workover” job?

Why it is necessary?

Reasons

The term workover is used to refer any

kind of intervention.

It refer to the very expensive process of

pulling and replacing a completion.

Workover operations are carried out for

mainly two reasons such as:

1) Mechanical problems

2) Reservoir Related Problems

a) Repair/Replace of damaged equipment

b) Capital repairs of well

c) Replace artificial lift equipments

d) Fishing

Downhole environments damage

equipments during the life of a well.

(Like Erosion, Chemical reactions,

Temperature extremes etc…)

Production tubing

Tubing packers

Subsurface safety valves etc…

Most complicated and time consuming

operations.

They include:

• Drilling and milling of packers.

• Detection & repair of casing damages &

recompletion

• Fishing & removal of stuck like tubings,

packers & other downhole tools &

recompletions.

When reservoir become unable to produce

at an economical rate, Then artificial lift is

required.

There are four basic types of artificial lift:

i) Rod pump

ii) Hydraulic pump

iii) Electric submersible pump (ESP)

iv) Gas lift

Retrieval of equipments from wellbore, (Expensive, Stucked & Reused) Such as:-

Drill pipes

Drill collars

Logging tools

Packers

Tubing etc…

a) Repair natural damage within the well

b) Zone Transfer

c) Stimulation

d) Convert well from production to injection

Term “Natural Damage” refers to damage

in the reservoir rock or the fluids within it.

For Example:

Near-Wellbore Formation Damage

Sand Production

Excessive Gas Production etc…

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.

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 (iii) Water Injection etc…

At certain time well production will be uneconomical

CO2 or water can be injected

Waste fluids or drilled cuttings can also be

injected

Advisor Sajjad Ali Jogi(146)