Production Engineering Technology

Production Engineering

Fundamental of petroleum Engineering course Peyman Maroufi Petroleum Engineering department LOGO Soran university

Wellhead facilities
Understanding the principles of fluid flow through the production system is important in estimating the performance of individual wells and optimizing well and reservoir productivity.
In the most general sense, the production system is the system that transports reservoir fluids from the subsurface reservoir to the surface, processes and treats the fluids, and prepares the fluids for storage and transfer to a purchaser.
The basic elements of the production system consists of: • A reservoir • Well • Tubular goods and associated equipment • Flow line • Separators • Pumps • Transportation pipelines. • Other processing equipment • artificial lift equipment

Wellhead facilities
The reservoir is the source of fluids for the production system.
It is the porous, permeable media in which the reservoir fluids are stored and through which the fluids will flow to the wellbore. It also furnishes the primary energy for the production system.
The wellbore serves as the conduit for access to the reservoir from the surface. It is composed of the drilled wellbore, which normally has been cemented and cased.
Once the production casing has been cemented into the well, the production tubing is run into the well. The cased wellbore houses the tubing and associated subsurface production equipment, such as packers.
The tubing serves as the primary conduit for fluid flow from the reservoir to the surface, although fluids also may be transported through the tubing-casing annulus.
The wellhead, flowlines, and processing equipment represent the surface mechanical equipment required to control and process reservoir fluids at the surface and prepare them for transfer to a purchaser.

Wellhead facilities  Surface mechanical equipment includes:


the wellhead equipment and associated valving




Chokes


Manifolds


Flowlines


Separators


Treatment equipment




Metering devices




Storage vessels

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Wellhead facilities  The Wellhead and Christmas tree
Wellhead and Christmas tree is used for well drilling and oil or gas production, water injection and downhole operation.
wellhead and christmas tree is installed on the top of a well to seal the annular space between casing and tubing, can control wellhead pressure and adjust well flow rate and transport oil from well to pipe line.

Wellhead facilities  Wellhead:
The equipment installed at the surface of the wellbore which is the mechanical connection between the Christmas tree and production tubing (and casing).
The purpose of a wellhead is to provide the suspension point and pressure seals for the casing strings that run from the bottom of the hole sections to the surface pressure control equipment.
A wellhead includes such equipment as the casing head and tubing head.

Wellhead facilities  Casing head:


A heavy flanged connection that is installed on top of a casing string. or




The adapter between the first casing string and either the BOP stack (during drilling) or the wellhead (after completion).




This flange may be threaded or welded onto the casing, and may have a flanged or clamped connection to match the BOP stack or wellhead.




This is the primary interface for the surface pressure control equipment, for example blowout preventers (for well drilling) or the Christmas tree (for well production).

Wellhead facilities  Casing spool: A wellhead component used in flanged wellhead assemblies to secure the upper end of a casing string.

Wellhead facilities  Casing hanger:
The casing hanger is that portion of a wellhead assembly which supports the casing string when it is run into the wellbore.
The casing hanger provides a means of ensuring that the string is correctly located and generally incorporates a sealing device or system to isolate the casing annulus from upper wellhead components.
When the casing string has been run into the wellbore it is hung off, or suspended, by a casing hanger, which rests on a landing shoulder inside the casing spool.
Casing hangers must be designed to take the full weight of the casing, and provide a seal between the casing hanger and the spool.

Wellhead facilities  Tubing head:
A flanged fitting or a body with two flange that can supports the tubing string on a oil well, seals off the pressure between the casing the outside of the tubing, and provides a means of attaching the Christmas tree to the wellhead.

 Tubing hanger:


A device attached to the topmost tubing joint in the wellhead to support the tubing string.




It is set in the tree or the wellhead and suspends the production tubing and/or casing.




Sometimes it provides porting to allow the communication of hydraulic, electric and other downhole functions, as well as chemical injection. It also serves to seal-in the annulus and production areas.

Wellhead facilities  Christmas tree:
An assembly of valves, spools, pressure gauges and chokes fitted to the wellhead (at the top of wellhead) of a completed well to control production or flow.


Christmas trees are available in a wide range of sizes and configurations, such as low- or high-pressure capacity and single- or multiple-completion capacity.

Wellhead facilities  Master valve:
The master valve is installed below the tee or cross that controls all flow from the wellbore.


A correctly functioning master valve is so important that two master valves are fitted to most Christmas trees. •

The upper master valve is used on a routine basis

•

The lower master valve providing backup or contingency function in the event that the normal service valve is leaking and needs replacement.

•

The lower master valve will normally be manually operated, while the upper master valve is often hydraulically actuated

Wellhead facilities  Wing valves (flow line valves): A valve on the wing of a Christmas tree. Two wing valves are generally fitted to a Christmas tree: 1) The right hand valve is often called the flow wing valve or the production wing valve, because it is in the flowpath the hydrocarbons take to production facilities (or the path water or gas will take from production to the well in the case of injection wells). 2) The left hand valve is often called the kill wing valve. It is primarily used for injection of fluids such as corrosion inhibitors or methanol to prevent hydrate formation. .

Wellhead facilities  Wellhead chokes Wellhead chokes are used to limit production rates for regulations, protect surface equipment from slugging, avoid sand problems due to high drawdown, and control flow rate to avoid water or gas coning.


Two types of wellhead chokes are used. (1) Positive (fixed) chokes (2) Adjustable chokes.


Placing a choke at the wellhead means fixing the wellhead pressure and, thus, the flowing bottom-hole pressure and production rate

Wellhead facilities  Swab valve:
The topmost valve on a Christmas tree that provides vertical access to the wellbore.

Wellhead facilities  Separator: • The fluids produced from oil wells are normally complex mixtures of hundreds of different compounds. • A typical oil well stream is a high-velocity, turbulent, constantly expanding mixture of gases and hydrocarbon liquids, intimately mixed with water vapor, free water, and sometimes solids. • The well stream should be processed as soon as possible after bringing them to the surface. Separators are used for the purpose. • A separator for petroleum production is a cylindrical or spherical vessel used to separate oil, gas and water from production fluids which produced by a well.

Wellhead facilities  Accordingly, oil-field separators can be classified into two types based on the number of phases to separate: 1) Two-phase separators, which are used to separate gas from oil in oil fields, or gas from water for gas fields. 2) Three-phase separators, which are used to separate the gas from the liquid phase, and water from oil.

Seprators  Based on the configuration, the most common types of separator are generally available from manufacturers: 1) horizontal 2) Vertical 3) spherical

Separators  Horizontal Separators:
Horizontal separators are usually the first choice because of their low costs.
Horizontal separators are almost widely used for high-GOR well streams, foaming well streams, or liquid-from-liquid separation.
They have much greater gas–liquid interface because of a large, long, baffled gasseparation section.

Separators
Horizontal separators are easier to skid-mount and service and require less piping for field connections. Individual separators can be stacked easily into stage-separation assemblies to minimize space requirements..

Separators  Vertical Separators:
Vertical separators are often used to treat low to intermediate GOR well streams and streams with relatively large slugs of liquid.


They handle greater slugs of liquid without carry over to the gas outlet, and the action of the liquid-level control is not as critical.


Vertical separators occupy less floor space, which is important for facility sites such as those on offshore platforms where space is limited.

Separators
Because of the large vertical distance between the liquid level and the gas outlet, the chance for liquid to re-vaporize into the gas phase is limited.
However, because of the natural upward flow of gas in a vertical separator against the falling droplets of liquid, adequate separator diameter is required.
Vertical separators are more costly to fabricate

Separators  Spherical separators
Spherical separators offer an inexpensive and compact means of separation arrangement.
Because of their compact configurations, these types of separators have a very limited surge space and liquid-settling section.
Also, the placement and action of the liquid-level control in this type of separator is more critical.

Sand Control

Fundamental of petroleum Engineering course Peyman Maroufi Petroleum Engineering department LOGO Soran university

Sand Control
Sand production is one of the oldest problems of the oilfield.
Conventional well completions in soft formations commonly produce formation sand or fines with fluids. These formations are usually geologically young (Tertiary age) and shallow, and they have little or no natural cementation.
In considering sand control, or formation solids control, it is necessary to differentiate between load bearing solids and fine solids associated with formation fluids which are not part of the mechanical structure of the formation.

Sand Control
Some fines are probably always produced. This is, in fact, beneficial since if fines are free to move, and if they are not produced, they, along with other fines moving in behind, must eventually block the flow channel.
Thus in defining sand control we mean control of the load bearing solids.

Sand Control  Causes of sand production are related to:
Drag forces of flowing fluid which increase with higher flow rates and higher fluid viscosity.
Reduction in formation "strength" often associated with water production due to dissolving or dispersion of cementing materials, or a reduction in capillary forces with increasing water saturation.
Reduced relative permeability to oil, due to increased saturation, which increases pressure drawdown for a given oil production rate.
Declining reservoir pressure which increases compaction forces and may disturb cementation between grains.

Sand Control  Sand Control Mechanisms Basically sand production can be controlled by three mechanisms: 1)

Reducing Drag Forces-This is often the cheapest and most effective. It should be considered along with any other method of control. It often is the natural outcome of proper well completion practices.

2) Bridging Sand Mechanically-This is the "old standby" and properly done, has wide application. It is more difficult to apply in multiple zones or small diameter casing. 3) Increasing Formation Strength-Sand consolidation has specialized applicationit leaves a full open wellbore and can be used in small diameter casing.