well workover

Well Work-over

AKHILOME .E. CHRISTIANS/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 WORKOVE

R

CONCLUSIONCONTENT

OUTLINE

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.

What is Work-Over

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.

What is Work-Over


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

Work-Over Operations


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

Steps in Work-over Operation


Is it really necessary for us…???


Reasons 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

Zone Transfer 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.


Re-Completion


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.


Replace Artificial lift Equipment

Stimulation 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.


Convert well from production to injection

ConclusionThe 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

Engineering