Ministry of Education of the Republic of Kazakhstan
Higher College APEC PetroTechnic
Chair of Special Disciplines
Course Work
№ Quality of work performance
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Independent systematization of the material
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within the specified period
Use of additional scientific literature
Uniqueness of the completed task
Task defense
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Witten by: Sultan Mukhit
Group: PFO 2-20k
Checked by: Zhanibek Khabbassov
Atyrau 2023
Well repair, work over and
equipments used
Outline
0
Introduction
3
1
4
2
Well repair
Interventions and each type
3
Challenges during well repairing
11
4
5
Difference between Workover and Well Repair
12
13
5.1
Types of Workover
Steps of Well Workover
Equipments that used for and description
15
Conclusion
References
32
5.2
6
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8
Workover
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Introduction
Well repair and workover are critical activities in the oil and gas industry that
involve the restoration or enhancement of oil and gas wells.
Over time, oil and gas wells can become damaged, experience declines in
production rates, or suffer from various operational issues. When this occurs, well
repair and workover activities become necessary to address the problem and ensure
that the well is functioning optimally. These activities can include everything from
re-perforating the wellbore to replacing damaged components and stimulating the
formation around the well. In this way, well repair and workover are essential for
maintaining and increasing the productivity of oil and gas wells, which is crucial
for meeting the world's growing energy demands.
Well repair and workover activities are complex and require the expertise of
trained professionals, including engineers, technicians, and other skilled workers.
These professionals use specialized tools and equipment to diagnose problems and
implement solutions, often working in challenging and sometimes hazardous
environments. The success of well repair and workover activities depends on a
thorough understanding of the well's geology, the type of reservoir, and the
specific production challenges facing the well. Given the high costs and risks
associated with these activities, it is critical to have a well-planned and carefully
executed approach to ensure the best possible outcomes. Well repair and workover
are ongoing processes that continue throughout the life of a well, from the initial
drilling and completion stages to the eventual abandonment or decommissioning.
Well repair
Repair of the oil-and-gas wells is a prerequisite in the process of installations in the
oil and gas industry. A malfunction of the main wells, occurring for many reasons,
lead to a significant reduction in its flowrate or to a full cessation of work. The
reason for the termination or reduction of production may be due to the failure of
the ground or underground equipment, a change of reservoir conditions, the
termination of gas supply or power supply, cessation of pumping and transport of
the liquid on the surface and other factors.
Therefore it requires immediate repair of oil and gas wells, as for some time idle
period take place. The frequency and the relative duration of the repair of oil and
gas wells are estimated by some parameters that characterize the organization and
technology of oil extraction.
The main thing in the repair of oil and gas wells is the quality of well casing and
insulation of productive reservoirs, prevention and / or troubleshooting of
underground part of the equipment and / or the wellbore, preventing gas emissions
that can lead to even more clogging of the porous medium, and consequently, the
subsequent reduction of the reservoir productivity.
Oil wells repair is characterized by the following groups of maintenance
1. Preparation: the arrival of the brigade atan accident zone, killing production
wells, placing the equipment in the wellhead and its installation, dismantling of
the wellhead equipment;
2. Repair work: performance of lowering lifting operations;
3. Final work: assembly of the wellhead equipment, start the well performance, its
commissioning, instruments and equipment cleaning from any contamination,
as well as dismantling and cleaning of the working area.
Sand plugs and sand production can appear during oil extraction and oil wells
repair, if the bottom-hole zone consists of weakly cemented rocks, which leads to
faults during the well operation, shutdown or a dead stop of oil supply. Blockages
are formed in production casing and tubing. In some cases, their amount can
exceed several hundred meters. To delete them, a variety of methods are used, for
example, bailer, lowered on a rope, where the winch is released 10-15 meters
before the plug, as a result, the valve is opened, and a certain amount of sand enters
the bailer. When the bailer is rais edits valve is closed, and the bailer liberated on
the surface is again lowered into the well.
Types of Well workover
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Repair and insulation;
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Shutdown of separate watered formation intervals;
Shutdown of separate formations;
Elimination of filed integrity of top cement;
Elevation of top cement behind production and intermediary casing;
Elimination of failed integrity of production casing;
Elimination of failed integrity by plugging;
Elimination of failed integrity by plaster installation;
Elimination of failed integrity by running additional small-size casing;
Elimination of accidents in course of operation or repair;
Retrieval of equipment from the hole after operational accident;
Elimination of production casing accidents;
Bottomhole and well hole treatment from metal objects;
Elimination of other accidents in course of well operation;
Elimination of accidents in course of well workover;
Transition to other zones and commingling of pay zones;
Transition to other zones;
Formation commingling;
Installation and repair of dual completion, dual injection units and packer
assemblies;
Underground drilling operation;
New hole drilling;
Top cement drilling;
Casing shoe cutting with well hole deepening in the rocks;
Surface hole and artesian well drilling;
Interventions
Well repair, also known as well intervention, refers to the process of restoring,
maintaining or enhancing the production of an oil or gas well. It involves a variety
of activities designed to address issues that may be affecting the productivity of the
well. These activities can range from relatively minor maintenance tasks to more
complex operations such as re-perforating the wellbore or replacing damaged
equipment.
There are several types of well repair interventions, each designed to address
specific issues that may be affecting the well's production. Here are some common
types of well repair interventions:
Mechanical Interventions: These interventions involve repairing or replacing
damaged or malfunctioning equipment within the wellbore, such as pumps, valves,
or tubing. This type of intervention is often necessary when mechanical issues are
affecting the flow of oil or gas from the well.
Some examples of mechanical interventions include:
Fishing operations: Fishing operations involve the use of specialized tools and
equipment to remove debris, stuck pipe, or other obstructions from the wellbore.
These tools can include overshots, junk baskets, and other types of specialized
fishing tools.
Perforating operations: Perforating operations involve the use of specialized guns
to create perforations in the casing or liner, allowing oil or gas to flow from the
reservoir into the wellbore.
Milling operations: Milling operations involve the use of milling tools to remove
damaged or obstructive components from the wellbore or completion. These tools
can be used to remove scale, cement, or other materials that may be blocking or
obstructing the wellbore.
Hydraulic fracturing: Hydraulic fracturing is a completion operation that involves
the use of hydraulic pressure to create fractures in the formation, allowing oil or
gas to flow more freely into the wellbore.
Cementing operations: Cementing operations involve the use of specialized
equipment to pump cement into the wellbore or annulus, sealing off the formation
and providing support for the casing or liner.
Re-perforation: Re-perforation involves the use of specialized perforating guns to
create new perforations in the casing or liner, either to increase the flow rate or to
target a different area of the reservoir.
These are just a few examples of the types of mechanical interventions that can be
used in workover and completion operations. The specific tools and equipment
used will depend on the nature of the operation and the specific requirements of the
well. Experienced well service professionals can help select and implement the
appropriate mechanical interventions for a given operation.
Chemical Interventions: These interventions involve injecting various chemicals
into the wellbore to stimulate the reservoir and enhance production. This may
include acidizing the well to dissolve mineral deposits or treating the well with
polymers to improve the flow of oil or gas. Examples of chemical interventions in
workover and completion operations include:
Acidizing: Acidizing involves the use of acid to dissolve materials that may be
obstructing the wellbore or limiting production. This can include removing scale,
cleaning out perforations, or stimulating the formation to increase production.
Friction reducers: Friction reducers are chemical additives that can be used to
reduce the friction between the fluid and the tubing or casing. This can help to
improve the flow rate and reduce the pressure drop in the wellbore.
Scale inhibitors: Scale inhibitors are chemicals that can be used to prevent the
buildup of scale in the wellbore or completion. This can help to maintain the flow
rate and prevent damage to the completion components.
Corrosion inhibitors: Corrosion inhibitors are chemicals that can be used to prevent
or reduce the corrosion of the wellbore or completion components. This can help to
prolong the life of the well and prevent equipment failure.
Biocides: Biocides are chemicals that can be used to control the growth of bacteria,
fungi, or other microorganisms in the wellbore or completion. This can help to
prevent plugging or corrosion caused by microbial activity.
Hydraulic Interventions: These interventions involve using hydraulic pressure to
improve production, such as by fracturing the formation surrounding the wellbore
to create new flow channels. Wellbore cleanout: Hydraulic cleanout operations use
a high-pressure fluid flow to remove debris and blockages from the wellbore. This
can include sand, scale, or other materials that may be obstructing the flow of fluid.
Hydraulic fracturing: Hydraulic fracturing is a completion operation that involves
the use of hydraulic pressure to create fractures in the formation, allowing oil or
gas to flow more freely into the wellbore.
Coil tubing operations: Coil tubing operations use a flexible tubing string to
perform a variety of tasks, such as cleanouts, perforating, and stimulation. The
tubing is often used in conjunction with hydraulic pressure to perform these tasks.
Snubbing operations: Snubbing operations use a hydraulic cylinder to push a pipe
string into the wellbore while maintaining wellbore pressure. This technique can be
used for a variety of tasks, such as fishing operations, completion operations, and
wellbore cleanouts.
Cementing operations: Cementing operations involve the use of specialized
equipment to pump cement into the wellbore or annulus, sealing off the formation
and providing support for the casing or liner. Hydraulic pressure is often used to
ensure that the cement is distributed evenly throughout the wellbore.
Electrical Interventions: These interventions involve the use of electrical tools,
such as logging tools, to assess the condition of the well and identify areas that
may require repair or maintenance.
Electric submersible pumps (ESPs): ESPs are used to lift fluid from the wellbore to
the surface. These pumps are powered by electricity and are often used in wells
that require high flow rates.
Electric wireline tools: Electric wireline tools are used to perform a variety of
tasks, such as logging, perforating, and setting plugs. These tools are powered by
electricity and are controlled from the surface.
Electric motors: Electric motors are used to power a variety of equipment, such as
pumps, compressors, and generators. These motors can be used in both surface and
downhole applications.
Electric heating systems: Electric heating systems can be used to prevent paraffin
or hydrate buildup in the wellbore. These systems use electrical resistance to
generate heat and keep the fluid flowing.
Electric packers: Electric packers are used to isolate zones in the wellbore. These
packers are powered by electricity and can be used to control the flow of fluid from
different zones.
Overall, the type of intervention used will depend on the specific challenges facing
the well, the type of well, and the geological conditions of the reservoir. A welltrained team of professionals, including engineers, technicians, and other skilled
workers, will typically be involved in carrying out the necessary well repair
interventions.
In the oil and gas industry, well repair is a critical activity that is necessary to
maintain the productivity of oil and gas wells. Over time, wells can become
damaged or experience declines in production rates due to a variety of factors,
including mechanical issues, reservoir conditions, or operational problems. Well
repair interventions are designed to address these issues and ensure that the well is
functioning optimally.
There are many types of well repair interventions that are commonly used in the oil
and gas industry. For example, mechanical interventions may involve repairing or
replacing damaged equipment within the wellbore, such as pumps, valves, or
tubing. Chemical interventions may involve injecting various chemicals into the
wellbore to stimulate the reservoir and enhance production. Hydraulic
interventions may involve using hydraulic pressure to improve production, such as
by fracturing the formation surrounding the wellbore to create new flow channels.
Electrical interventions may involve using electrical tools to assess the condition of
the well and identify areas that may require repair or maintenance.
Well repair activities in the oil and gas industry require the expertise of trained
professionals, including engineers, technicians, and other skilled workers. These
professionals use specialized tools and equipment to diagnose problems and
implement solutions, often working in challenging and sometimes hazardous
environments. Given the high costs and risks associated with these activities, it is
critical to have a well-planned and carefully executed approach to ensure the best
possible outcomes.
Overall, well repair is an essential component of the oil and gas industry, playing a
crucial role in ensuring the continued production of energy resources and meeting
the world's growing energy needs.
In addition to the types of well repair interventions mentioned earlier, there are
many other factors that can impact the effectiveness and success of well repair
activities in the oil and gas industry. For example, the geological characteristics of
the reservoir can play a significant role in determining the most appropriate
interventions to use. Additionally, the type of well and its operating conditions can
impact the feasibility and cost-effectiveness of different repair options.
To ensure the success of well repair activities, it is essential to have a thorough
understanding of the well's history, current condition, and potential issues that may
arise in the future. This requires careful monitoring and analysis of well data,
including production rates, pressure, and temperature measurements, to identify
any changes or anomalies that may indicate a problem. Additionally, regular
maintenance and preventative measures can help to reduce the risk of future issues,
such as corrosion, scaling, or equipment failure.
Another important consideration in well repair activities is the potential impact on
the environment and surrounding communities. Drilling and well repair activities
can have significant environmental impacts, such as water contamination, air
pollution, and disruption to ecosystems. Therefore, it is critical to follow best
practices and regulations to minimize these impacts and ensure the safe and
responsible operation of oil and gas wells.
Overall, well repair is an important and ongoing activity in the oil and gas industry,
requiring careful planning, execution, and ongoing monitoring to ensure the
continued production of energy resources in a safe and sustainable manner.
Challenges of well repair
One of the challenges in well repair and maintenance is identifying and addressing
issues before they escalate into major problems. Regular monitoring and
maintenance can help to detect issues early, preventing them from becoming more
severe and costly to address. This can include activities such as inspecting
equipment and performing routine maintenance on pumps, valves, and other
components. Additionally, well logging and data analysis can provide valuable
insights into the condition of the well and help to identify potential issues before
they become critical.
Another important consideration in well repair and maintenance is ensuring that all
work is carried out safely and in compliance with relevant regulations and industry
standards. This includes implementing appropriate safety protocols and
procedures, providing training and protective equipment for workers, and
conducting regular safety audits to identify and address any potential hazards.
Advances in technology are also having a significant impact on well repair and
maintenance in the oil and gas industry. For example, new diagnostic tools and
sensors can provide real-time data on well conditions and help to identify potential
issues more quickly and accurately. Automated systems and robotics can also be
used to perform certain maintenance tasks, reducing the risk of human error and
increasing efficiency.
In conclusion, well repair and maintenance is an essential activity in the oil and gas
industry, ensuring the continued production of energy resources while minimizing
environmental impacts and ensuring the safety of workers and surrounding
communities. With ongoing monitoring, regular maintenance, and the use of
advanced technology and best practices, well repair and maintenance can help to
optimize well performance and extend the lifespan of oil and gas wells.
Difference between Well repair and
Workover
Well repair and workover are two different operations in the oil and gas industry,
although they both involve interventions on an existing well.
Well repair typically refers to minor repairs and maintenance performed on a
producing well to ensure it continues to function properly. This can include
repairing leaks, replacing faulty equipment, or cleaning out the wellbore. Well
repair activities typically involve minor interventions that can be performed
quickly and without shutting down the well.
Workover, on the other hand, involves more extensive interventions on a well that
is no longer producing at its optimal level. Workovers can be performed to
enhance the productivity of the well, repair equipment, or change the completion
design to allow for access to additional reserves. Workovers typically require more
time and resources than well repairs and may require the well to be shut down
temporarily.
In summary, well repair is focused on maintaining a producing well, while
workover is focused on improving the production or extending the life of a well
that has already experienced some decline in production.
Workover
In the oil and gas industry, workover refers to the process of performing major
interventions on an existing well to restore or enhance its productivity. A workover
operation can be required for a variety of reasons, such as equipment failure, sand
or scale accumulation, formation damage, or to target a new zone.
The process of workover typically involves the following steps:
Well evaluation: The well is evaluated to determine the cause of its reduced
productivity, the necessary repairs or modifications, and the estimated cost of the
workover operation.
Planning and design: A workover plan is developed based on the evaluation,
including the selection of equipment, materials, and techniques to be used during
the operation. The plan is reviewed and approved by all relevant stakeholders,
including regulatory agencies.
Rig mobilization: A rig is mobilized to the well site, along with any necessary
equipment, materials, and personnel.
Well shut-in: The well is shut-in to allow for safe access to the wellbore and
surface equipment.
Intervention: Various interventions are performed to restore or enhance the well's
productivity. This may include fishing, perforating, cleaning out the wellbore,
repairing equipment, or re-completing the well.
Well testing: The well is tested to evaluate its productivity and ensure that it is
operating within safe and regulatory guidelines.
Well completion: After the workover is completed, the well is brought back into
production and returned to its normal operating condition.
Workovers can be complex and expensive operations, but they can also be very
effective in extending the life of an existing well and maximizing its productivity.
This process involves removing the tubing, the packer, and other downhole
equipment to access the wellbore, where various operations such as cleaning,
repairing, and replacing components can be performed. Workover operations are
typically conducted to address issues such as sand control, perforation damage,
casing leaks, scale buildup, or to increase production. The workover process can be
complex and costly, requiring specialized equipment and personnel with extensive
knowledge and experience in well operations.
These operations are carried out after the well has been drilled, completed, and
produced for some time, and may involve a variety of interventions to clean,
repair, or replace the downhole equipment and formations.
Some of the common workover operations in oil and gas include:
Tubing or casing replacement: If the tubing or casing in the wellbore is damaged or
corroded, it may need to be replaced to maintain production.
Stimulations: This process involves pumping fluids, such as acid or water, into the
wellbore to increase the flow of hydrocarbons to the surface.
Fishing: This refers to the process of retrieving lost or stuck equipment from the
wellbore, such as broken drill bits or tubing.
Perforation: This involves creating holes in the wellbore casing to allow
hydrocarbons to flow into the wellbore.
Plugging and abandonment: When a well is no longer productive or safe to
operate, it must be plugged and abandoned to prevent environmental contamination
and hazards.
Workover operations can be carried out using various tools and equipment, such as
coiled tubing units, workover rigs, and wireline units. These operations are
typically conducted by specialized workover crews and can involve significant
costs and risks. However, they are essential for maintaining the production and
profitability of oil and gas wells over their lifespan.
Workover operations are often required due to changes in reservoir conditions,
equipment failures, or other factors that can impact the productivity of a well.
Some of the most common reasons for workovers include:
Mechanical failures: Equipment such as pumps, valves, and tubing may fail due to
normal wear and tear or exposure to harsh downhole conditions. Workovers may
be necessary to repair or replace this equipment. Causes by blowout.
Declining production rates: Over time, a well may become less productive due to
factors such as formation damage, scaling, or other issues. Workovers can help to
restore or improve production rates.
Wellbore blockages: Deposits of scale, sand, or other materials can accumulate in
the wellbore over time and obstruct the flow of hydrocarbons. Workovers may be
needed to remove these blockages.
Changes in reservoir conditions: The characteristics of a reservoir may change over
time, such as due to pressure depletion or water breakthrough. Workovers may be
required to adjust the well's production strategy accordingly.
Types of Workover
Workovers can be divided into two main categories: light and heavy workovers.
Light workovers involve minor maintenance and repairs, such as replacing tubing
or cleaning out the wellbore.
To replace tubing in the oil industry, specialized equipment and techniques are
used to safely remove the old tubing and install new tubing in its place.
Cleaning out the wellbore is an important part of maintaining oil and gas wells.
Over time, debris, scale, sand, and other materials can accumulate in the wellbore,
which can impede production, reduce flow rates, and increase the risk of
equipment failure.
Cleaning out the wellbore involves removing these obstructions to restore proper
flow and production rates.
Heavy workover
Heavy workover in the oil industry is a type of intervention that involves
performing major repairs, maintenance, or upgrades to a well. This type of
operation is typically necessary when a well experiences significant issues such as
equipment failure, decreased production, or wellbore instability.
A heavy workover can involve a variety of activities, such as:
Pulling the tubing or casing to replace or repair damaged components.
Installing new pumps or other artificial lift equipment to increase production
rates.
Performing a well stimulation treatment such as hydraulic fracturing to
enhance productivity.
Installing new completion equipment such as packers, screens, or liners to optimize
production.
Re-perforating the wellbore to target additional productive zones.
Heavy workover operations require specialized equipment and highly skilled
personnel to perform safely and effectively. They can be time-consuming and
expensive, but are often necessary to maintain or improve the productivity of oil
and gas wells.
Installing new pumps or other artificial lift equipment is a common method
used in the oil and gas industry to increase production rates of a well. Artificial lift
equipment is used to increase the flow of hydrocarbons to the surface by reducing
the pressure in the wellbore. This is typically necessary when the natural reservoir
pressure has declined to a point where it can no longer lift the fluids to the surface.
Hydraulic fracturing involves injecting high-pressure fluids into the wellbore to
create fractures in the reservoir rock. This allows for increased flow of
hydrocarbons to the wellbore and ultimately to the surface.
Д
Steps of Well Workover
Well evaluation is a critical process in the oil and gas industry that involves
analyzing various aspects of a well to determine its potential productivity,
economic viability, and safety. The evaluation process typically involves a
combination of geological, geophysical, and engineering techniques to gain a
comprehensive understanding of the subsurface reservoir and the production
potential of the well.
Here are some of the aspects that are evaluated in well evaluation:
Geology: The geological characteristics of the reservoir, such as formation type,
depth, and thickness, are evaluated to determine the potential for hydrocarbon
accumulation and the quality of the reservoir rock.
Geophysics: Geophysical methods such as seismic surveys, gravity surveys, and
electromagnetic surveys are used to image the subsurface and provide information
on the size, shape, and location of the reservoir.
Well logs: Various types of well logs, including gamma ray logs, resistivity logs,
and sonic logs, are used to evaluate the properties of the reservoir rock and identify
potential hydrocarbon-bearing zones.
Reservoir engineering: Reservoir engineering techniques are used to model the
flow of fluids within the reservoir and determine the potential production rates of
the well.
Wellbore integrity: The integrity of the wellbore and the casing is evaluated to
ensure that the well is safe to produce and does not pose a risk of leakage or
blowout.
Based on the results of the well evaluation, decisions can be made regarding the
design and operation of the well, including the type of completion equipment to
install, the artificial lift method to use, and the production rates to target.
Planning and design are critical aspects of workover operations, as they help to
ensure that the work is completed safely, efficiently, and effectively.
The planning phase of a workover operation involves determining the objectives of
the operation, identifying the resources and equipment needed, and developing a
detailed plan for carrying out the work. This may involve conducting a site survey
to assess the condition of the well and identify any potential hazards or obstacles
that may need to be addressed.
During the design phase, the specific techniques and procedures to be used in the
workover operation are identified and documented. This may involve selecting the
appropriate type of completion equipment, determining the optimal wellbore
configuration, and developing a plan for the use of hydraulic fracturing or other
stimulation techniques.
In addition to technical considerations, planning and design in workover operations
also involve a focus on safety and risk management. This may include identifying
potential hazards, implementing appropriate safety procedures, and developing
contingency plans for addressing unexpected events.
Overall, effective planning and design are essential for successful workover
operations. By carefully considering the objectives, resources, and potential risks
associated with a workover operation, operators can minimize the likelihood of
delays, accidents, and other problems, and ensure that the well is restored to its full
productivity potential.
Rig mobilization is the process of moving a workover rig from one location to
another in preparation for a new workover operation. Rig mobilization is a critical
aspect of workover operations, as it can impact the safety, efficiency, and
effectiveness of the work that is to be performed.
The rig mobilization process typically involves several stages, including
preparation, transportation, and rigging up at the new location. During the
preparation stage, the rig crew will perform a series of tasks to ensure that the rig is
in good working condition and ready for transport. This may include inspecting the
rig components, preparing equipment and tools for transport, and securing the rig
for transit.
Once the rig is ready for transport, it will be loaded onto a specialized transport
vehicle and transported to the new location. During the transportation phase, the
rig crew will need to ensure that the rig is securely fastened and that it is
transported in compliance with local regulations and safety standards.
Upon arrival at the new location, the rig crew will begin the rigging up process,
which involves assembling and connecting the various components of the rig, such
as the mast, substructure, and power system. This process may take several days
and requires careful coordination and attention to detail to ensure that the rig is set
up correctly and safely.
Overall, rig mobilization is a complex and time-consuming process that requires
careful planning, coordination, and execution. By following established procedures
and guidelines, and by prioritizing safety and efficiency, rig crews can ensure that
the rig mobilization process is completed successfully and that workover
operations can proceed as planned.
One important aspect of rig mobilization is the selection of the appropriate
transport vehicle for the rig. The type of transport vehicle used will depend on
factors such as the size and weight of the rig, the distance to be traveled, and local
regulations and road conditions. In some cases, multiple vehicles may be needed to
transport the rig components to the new location.
Another important consideration during rig mobilization is the preparation of the
new work site. This may involve clearing the area of debris or obstructions,
leveling the ground to ensure stability, and preparing the well for the upcoming
workover operation. The rig crew will also need to ensure that there is adequate
space and access for the rig to be set up safely and effectively.
Well shut-in refers to the process of temporarily suspending production or
injection from an oil or gas well. Shutting in a well can be done for a variety of
reasons, such as maintenance or repair, production optimization, or to prevent
damage to the well or reservoir.
During a shut-in operation, the production or injection equipment is stopped and
the wellbore is sealed off using specialized equipment such as a Christmas tree or a
wellhead valve. Shut-in procedures may vary depending on the type of well and
the nature of the operation, but generally involve a series of steps to ensure that the
well is properly sealed and secured.
Shutting in a well can have both short-term and long-term effects on the well and
the reservoir. In the short term, shutting in a well can allow pressure to build up in
the reservoir, which can increase the productivity of the well when it is brought
back online. Shutting in a well can also allow for maintenance or repairs to be
performed on the production or injection equipment, which can improve the longterm productivity and efficiency of the well.
However, there are also potential risks associated with shutting in a well, such as
damage to the formation due to changes in pressure or temperature, or the
accumulation of corrosive fluids in the wellbore. To minimize these risks, well
shut-in procedures must be carefully planned and executed, and the well must be
monitored regularly to ensure that it remains secure and stable.
Overall, well shut-in is an important tool for managing oil and gas production and
ensuring the long-term productivity of a well. By following established procedures
and guidelines, and by prioritizing safety and efficiency, operators can ensure that
the well shut-in process is completed successfully and that the well remains stable
and productive over the long term.
Shutting in a well can also be done in response to certain operational or safety
issues, such as the presence of dangerous gas concentrations or equipment
malfunctions. In these cases, the shut-in procedure may be initiated more quickly
and require more urgent attention to ensure that the well is properly secured and
the risk of accidents or injuries is minimized.
Once a well is shut-in, it must be monitored regularly to ensure that the pressure
and temperature levels remain within safe and stable ranges. This may involve
periodic testing of the wellbore, as well as monitoring of surface pressure and
temperature gauges. Regular monitoring is important to prevent well damage or
failure, and to ensure that the well can be brought back online safely and efficiently
when necessary.
Intervention in workover refers to the process of performing maintenance or
repair operations on an oil or gas well to restore or enhance its productivity.
Workover interventions can include a variety of activities, such as cleaning out the
wellbore, repairing or replacing production equipment, or stimulating the reservoir
to increase production.
There are several types of interventions that may be performed during workover
operations, including:
Mechanical interventions: These involve the use of mechanical equipment such as
coiled tubing, wireline, or slickline to perform tasks such as cleaning out the
wellbore, repairing or replacing downhole equipment, or installing new equipment
to enhance production.
Hydraulic interventions: These involve the use of hydraulic fracturing or acidizing
to stimulate the reservoir and increase production. Hydraulic fracturing involves
injecting a fluid under high pressure to create fractures in the rock formation, while
acidizing involves using acid to dissolve minerals and increase permeability in the
reservoir.
Thermal interventions: These involve the use of heat to enhance production by
melting or reducing the viscosity of heavy oil or bitumen. Thermal interventions
can include methods such as steam injection, in which steam is injected into the
reservoir to heat the oil and increase flow rates.
Interventions in workover operations can be complex and require specialized
knowledge and equipment. It is important to carefully plan and execute workover
interventions to ensure that they are effective and do not cause damage to the well
or the reservoir. Well intervention specialists and engineers work closely to
determine the most appropriate intervention method based on the specific
conditions of the well and the reservoir, and to ensure that all safety protocols are
followed during the operation.
Workover interventions can be divided into two categories: routine and nonroutine interventions. Routine interventions are performed regularly as part of
normal maintenance or production enhancement activities, and typically involve
relatively simple tasks such as cleaning out the wellbore or replacing worn-out
equipment. Non-routine interventions, on the other hand, are performed in
response to unexpected problems or changes in well performance, and may require
more complex and specialized interventions to address the issues.
The choice of intervention method depends on the specific problem being
addressed and the characteristics of the well and reservoir.
Well testing in workover refers to the process of evaluating the production
potential of an oil or gas well after a workover intervention has been performed.
Well testing is an essential step in determining the effectiveness of the intervention
and in optimizing production from the well.
Well testing involves a series of measurements and analyses to determine the well's
flow rate, pressure, and other important production parameters. During a well test,
the well is typically shut-in for a period of time to allow pressure to build up in the
reservoir. After the shut-in period, the well is opened and the flow rate and
pressure are measured using specialized equipment such as a flowmeter or a
pressure gauge.
Well testing can also include other types of measurements, such as fluid analysis to
determine the composition of the production fluids and to identify any potential
issues such as scaling or corrosion. Well testing may also involve downhole
measurements, such as temperature or pressure measurements taken using
specialized tools that are lowered into the wellbore.
The results of a well test are used to determine the potential productivity of the
well and to optimize production. If the well is producing at a rate below its
potential, additional workover interventions may be required to address any
remaining issues. If the well is producing at or above its potential, the well test
results can be used to optimize the production equipment and to ensure that the
well is producing at maximum efficiency.
Overall, well testing is an important step in the workover process, as it provides
critical information on the performance of the well and on the effectiveness of the
intervention. By carefully analyzing the results of well tests, operators can
optimize production and ensure the long-term productivity of the well.
Well completion in workover refers to the final stage of workover operations, in
which production equipment is installed in the wellbore to enable the production of
oil or gas. Completion is a critical step in the workover process, as it ensures that
the well can be brought into production safely and efficiently.
The completion process typically involves several steps, including:
Installing production tubing: Production tubing is installed in the wellbore to allow
oil or gas to flow from the reservoir to the surface. The tubing is typically made of
steel and is inserted into the wellbore using specialized equipment such as a tubing
hanger.
Installing packers: Packers are devices that are used to isolate different sections of
the wellbore and to prevent the migration of fluids between these sections. Packers
are installed at the top and bottom of the production interval to ensure that
production flows only from the desired zone.
Installing completion equipment: Completion equipment such as pumps, valves,
and choke assemblies are installed in the wellbore to regulate the flow of
production fluids and to ensure that the well can be operated safely and efficiently.
Installing surface equipment: Surface equipment such as separators, tanks, and
pipelines are installed to enable the production fluids to be transported from the
well to the processing facilities.
Once the completion process is complete, the well is ready to be brought into
production. Initial production rates are typically lower than the long-term
production rates, as the reservoir pressure and flow rates gradually stabilize over
time. The well is continuously monitored to ensure that it is operating safely and
efficiently, and additional workover interventions may be performed as needed to
optimize production.
Overall, well completion is a critical step in the workover process, as it ensures
that the well can be brought into production safely and efficiently. By carefully
designing and executing the completion process, operators can ensure the longterm productivity of the well and maximize the return on their investment.
Equipments
There are several pieces of equipment that are commonly used for well repair and
workover operations. Some of these include:
Workover rig: A workover rig is a specialized piece of equipment used to perform
well repair and maintenance operations. Workover rigs are typically smaller and
more mobile than drilling rigs, and are designed to be quickly transported to and
set up on the well site.
Coiled tubing unit: Coiled tubing is a continuous length of steel tubing that is
spooled onto a reel and fed into the wellbore without the need for drilling. A coiled
tubing unit is a piece of equipment that is used to deploy and retrieve the coiled
tubing, and to perform various well intervention operations such as cleaning,
stimulation, and logging.
Wireline unit: A wireline unit is a specialized truck-mounted unit that is used to
run and retrieve wireline tools in the wellbore. Wireline tools are used for a variety
of purposes, including logging, perforating, and setting or retrieving downhole
plugs.
Snubbing unit: A snubbing unit is a specialized piece of equipment that is used for
well control during workover operations. A snubbing unit consists of a hydraulic
workover unit and a snubbing unit that are combined to provide pressure control
and to prevent wellbore fluids from escaping during the operation.
Fishing tools: Fishing tools are specialized tools used to recover lost or damaged
equipment from the wellbore. Fishing tools include items such as overshots,
spears, and junk baskets, and are designed to retrieve equipment such as drill bits,
casing, and tubing that have become stuck or lost in the wellbore.
Wellhead equipment: Wellhead equipment is used to control the flow of fluids into
and out of the wellbore. This equipment includes items such as wellheads, valves,
and Christmas trees, and is used to regulate the flow of production fluids and to
prevent wellbore blowouts.
Pumping unit: A pumping unit is used to inject fluids into the wellbore during well
stimulation or fracturing operations. Pumping units can be truck-mounted or
trailer-mounted and are typically powered by diesel engines.
Flowback equipment: Flowback equipment is used to manage the flow of fluids
from the well during production or testing. Flowback equipment includes items
such as separators, tanks, and pipelines, and is used to separate and collect the
production fluids.
Cementing unit: A cementing unit is used to pump cement into the wellbore to seal
off zones or to anchor production casing. Cementing units typically include pumps,
mixers, and pressure-control equipment.
Pressure-control equipment: Pressure-control equipment is used to regulate the
pressure in the wellbore during drilling, completion, and workover operations. This
equipment includes items such as blowout preventers (BOPs), choke manifolds,
and hydraulic power units.
Downhole tools: Downhole tools are specialized tools that are used to perform
various operations in the wellbore. These tools include items such as mills, bits,
and packers, and are used to remove obstructions, clean out the wellbore, and
perform other tasks.
Well testing equipment: Well testing equipment is used to measure the production
rate and other characteristics of the well. Testing equipment includes items such as
flow meters, pressure gauges, and sample collection equipment, and is used to
optimize production and to ensure that the well is operating safely and efficiently.
These are just a few of the many pieces of equipment that are used for well repair
and workover operations. The selection of equipment will depend on a variety of
factors, including the nature of the problem, the type of well, and the goals of the
operation.
The main equipments that used for workover operations;
The workover rig is a type of drilling rig that is specifically designed for well
repair and maintenance operations. Workover rigs are typically smaller and more
mobile than drilling rigs, and are used to perform a variety of tasks such as pulling
and replacing tubing, cleaning out the wellbore, and repairing or replacing
downhole equipment.
A typical workover rig consists of a mast, which supports the drilling or workover
equipment; a drawworks, which is used to hoist equipment and pipe in and out of
the wellbore; and a power source, which provides the necessary energy to operate
the rig. Workover rigs may also be equipped with a variety of specialized
equipment, such as wireline units, coiled tubing units, and well control equipment.
Workover rigs come in a variety of sizes and configurations, depending on the
specific needs of the operation. Some workover rigs are truck-mounted, allowing
for easy transportation from one site to another, while others may be skid-mounted
or trailer-mounted for increased mobility. The selection of a workover rig will
depend on a variety of factors, including the size and depth of the well, the type of
wellbore, and the nature of the work to be performed.
The BOP (blowout preventer) stack is a critical piece of equipment used in
drilling and workover operations to control the flow of fluids in the wellbore and
prevent blowouts, which can have catastrophic consequences.
The BOP stack is typically composed of several components, including:
Annular preventer: This component is designed to seal around the drill pipe or
workover equipment, preventing fluid from escaping the wellbore.
Ram preventers: These are large, hydraulic-powered rams that are designed to seal
off the wellbore in the event of a blowout. There are several types of ram
preventers, including blind rams, pipe rams, and shear rams, each designed for
specific types of wellbore conditions.
Choke and kill lines: These lines provide a means of controlling the pressure and
flow of fluids in the wellbore, allowing for safe well control operations.
The BOP stack is typically mounted on top of the wellhead and is operated by a
hydraulic control system. During drilling or workover operations, the BOP stack is
used to control the pressure and flow of fluids in the wellbore, as well as to prevent
any potential well control issues from escalating into a blowout. In the event of a
well control emergency, the BOP stack can be activated to shut off the well,
allowing for emergency response personnel to take appropriate action to contain
and mitigate the situation.
Downhole tools are specialized equipment that is used in workover and drilling
operations to perform various tasks inside the wellbore. These tools are typically
designed to be run on a wireline or coiled tubing, and are operated remotely from
the surface.
Some common types of downhole tools used in workover operations include:
Packers: Packers are devices that are used to isolate different sections of the
wellbore, allowing for zonal isolation and more efficient production or injection
operations.
Bridge plugs: Bridge plugs are used to temporarily seal off a section of the
wellbore, allowing for pressure testing, stimulation treatments, or other operations.
Fishing tools: Fishing tools are used to recover lost or stuck equipment from the
wellbore, such as drill pipe, tubing, or other downhole tools.
Perforating guns: Perforating guns are used to create perforations in the well casing
or formation, allowing for the flow of oil, gas, or water into the wellbore.
Downhole cameras and sensors: These tools are used to monitor the condition of
the wellbore and downhole equipment, allowing for real-time monitoring of well
conditions and identifying potential issues before they become critical.
The selection of downhole tools will depend on the specific needs of the operation
and the type of wellbore being worked on. Different tools may be required for
different wellbore conditions, and experienced well service professionals can help
select the appropriate tools for the job.
Pressure-control equipment is a critical component of workover operations, as it
is used to control and maintain the pressure within the wellbore, preventing
blowouts and other well control issues. Pressure-control equipment includes a
variety of specialized equipment and tools, such as:
BOP (blowout preventer) stack: The BOP stack is a system of valves and rams that
is used to prevent the uncontrolled release of fluids from the wellbore.
Choke and kill manifold: The choke and kill manifold is a series of valves and
piping that is used to control the flow of fluids in the wellbore, allowing for safe
well control operations.
Hydraulic power unit: The hydraulic power unit provides the hydraulic pressure
needed to operate the BOP stack and other pressure-control equipment.
Pressure gauges and sensors: Pressure gauges and sensors are used to monitor the
pressure within the wellbore and at various points in the pressure-control system,
allowing for real-time monitoring of well conditions.
Accumulator unit: The accumulator unit is a hydraulic storage unit that provides
backup hydraulic pressure in the event of a power failure or other issue with the
hydraulic power unit.
Pressure-control equipment is typically designed and installed to meet specific well
conditions and requirements, and experienced well service professionals can help
select and install the appropriate equipment for a given operation. Regular
maintenance and inspection of pressure-control equipment is also critical to
ensuring the safe and efficient operation of the wellbore.
Well testing equipment is used in workover and completion operations to
measure and evaluate the characteristics of fluids produced from the wellbore.
Some common types of well testing equipment include:
Pressure gauges: Pressure gauges are used to measure the pressure of fluids within
the wellbore and at various points in the wellhead and production system.
Flow meters: Flow meters are used to measure the rate of fluid flow from the
wellbore, providing important data on well performance and production rates.
Sample catchers: Sample catchers are used to collect fluid samples from the
wellbore, which can be analyzed for composition, temperature, pressure, and other
characteristics.
Gas detectors: Gas detectors are used to monitor the wellhead and production
system for the presence of flammable or toxic gases, ensuring the safety of
personnel and equipment.
Well logging tools: Well logging tools are used to measure the properties of the
formation surrounding the wellbore, providing important data on reservoir
characteristics, porosity, and permeability.
Well testing equipment is typically selected and installed based on the specific
requirements of the operation and the characteristics of the wellbore. Experienced
well service professionals can help select and install the appropriate equipment for
a given operation, and ensure that it is properly calibrated and maintained to
provide accurate and reliable data.
Conclusion
In conclusion, well repair and workover operations are an essential part of the oil
and gas industry. These operations involve the maintenance, repair, and
optimization of existing wells to maximize production and ensure safety. The
process involves a variety of interventions, such as mechanical, chemical,
hydraulic, and electrical, that use specialized equipment to perform specific tasks.
The success of these operations relies heavily on the experience and expertise of
the well service professionals involved. Through proper planning, design, and
execution, well repair and workover operations can help extend the lifespan of
existing wells, increase production, and ensure the safety and integrity of the well
and surrounding environment.
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