process training

8/4/2019 Process Training

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ByAmmad Baig

Upstream Oil Production ProcessTraining


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Oil Exploration and Production

Upstream

The upstream sector includes thesearching for potential underground or

underwater oil and gas fields, drilling ofexploratory wells, and subsequentlyoperating the wells that recover andbring the crude oil and/or raw natural

gas to the surface [2]


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Oil Exploration and Production

Midstream

Midstream operations are usually included in thedownstream category. The midstream industry

processes, stores, markets and transportscommodities such as crude oil, natural gas,natural gas liquids (LNGs, mainly ethane,propane and butane) and sulphur.

Downstream

The downstream sector includes oil refineries,petrochemical plants, petroleum productdistribution, retail outlets and natural gasdistribution companies


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Upstream Process

Offshore and Onshore Reservoirs

Well Formation

Collection of Crude Oil from Wells

Separates Gas

Oil Processing to remove

Sulfur

Water

Salts

Shipping oil to storage facilities


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GS Process OIL Flow

WellsReceiverManifold

ProductionSeparators

ChargePumps

CrudeHeaters

FWNO,DESALTERSTreater

SurgeTank

ShippingPumps

Metering

LauncherManifold


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Oil Reservoirs

A petroleum reservoir or an oil and gasreservoir, is a subsurface pool ofhydrocarbons contained in porous rock

formations. The naturally occurringhydrocarbons are trapped by overlying rockformations with lower permeability [2]

These formations occur over a period of

millions of years. A young reservoir is saidto be 60 million years old. Older reservoirshave better API Oil Grade. [1]


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Oil Reservoir

Seismic data and advancedvisualization 3D models are used toplan extractions. Normally a well willprovide 30 - 60 % extractions.However by using EOR (Enhanced OilRecovery) techniques 70 % can be

achieved. [1]


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Oil Wells and Reservoir Engg.

The well sits on the actual oil/gasreservoir:

1.)Oil Wells

2.)Gas Wells

3.) Condensate Gas wells

Various types of wells:

1.) Subsea

2.) Onshore


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Structure of Oil Well

Well Casing: Series of metal tubes installed in a

freshly drilled hole. It strengthens thesides of the hole, ensures nohydrocarbons leak out or seep into thewall formation. The type of casingdepends upon the depth, temp, pressureand formation of the well. Casing is

usually cemented in place. [2] Usually the diameter of the well

decreases as it is dug deeper leading toa type of colonial shape. [1]


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Casing Structure

Conductor Casing

20 50 feet long

Surface Casing

100 400 meters long

Intermediate Casing

Longest casing string

Production Casing

Oil string, connects oil reservoir to surface casings

A packer is used between casing andtubing at the bottom of the well.

Structure of Oil Well


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Structure of Oil Well Completion:

Refers to process of finishing the well forproduction. This principally involves preparingthe bottom of the hole to the requiredspecifications, running in the production tubing

and its associated jewellery and perforating andstimulating as required. Following are a few types of completion. Open Hole completion Perforated Completion

Sand Exclusion Completion Permanent Completion Multiple Zone Completion Drain Hole Completion


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Completion After drilling and casing the well, it must be 'completed'. Completion is the

process in which the well is enabled to produce oil or gas. In a cased-hole completion, small holes called perforations are made in the

portion of the casing which passed through the production zone, to providea path for the oil to flow from the surrounding rock into the production

tubing. In open hole completion, often 'sand screens' or a 'gravel pack' isinstalled in the last drilled, uncased reservoir section. These maintainstructural integrity of the wellbore in the absence of casing, while stillallowing flow from the reservoir into the wellbore. Screens also control themigration of formation sands into production tubulars and surfaceequipment, which can cause washouts and other problems, particularlyfrom unconsolidated sand formations in offshore fields.

After a flow path is made, acids and fracturing fluids are pumped into thewell to fracture, clean, or otherwise prepare and stimulate the reservoir

rock to optimally produce hydrocarbons into the wellbore. Finally, the areaabove the reservoir section of the well is packed off inside the casing, andconnected to the surface via a smaller diameter pipe called tubing. Thisarrangement provides a redundant barrier to leaks of hydrocarbons as wellas allowing damaged sections to be replaced. Also, the smaller diameter ofthe tubing produces hydrocarbons at an increased velocity in order toovercome the hydrostatic effects of heavy fluids such as water.

In many wells, the natural pressure of the subsurface reservoir is high

enough for the oil or gas to flow to the surface. However, this is not alwaysthe case, especially in depleted fields where the pressures have beenlowered by other producing wells, or in low permeability oil reservoirs.Installing a smaller diameter tubing may be enough to help the production,but artificial lift methods may also be needed. Common solutions includedown hole pumps, gas lift, or surface pump jacks. Many new systems in thelast ten years have been introduced for well completion. Multiple packersystems with frac ports or port collars in an all in one system have cutcompletion costs and improved production, especially in the case of

horizontal wells. These new systems allow casings to run into the lateralzone with proper packer/frac port placement for optimal hydrocarbonrecovery.


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Wellhead

The wellhead consists of pieces of equipment mounted at theopening of well to regulate and monitor the extraction ofhydrocarbons from underground formation.

A wellhead consists of three components The casing head

At the bottom. Connected to hanger. Gives access to open, close, bled down and in some caseproduce through casing as well.

Used to determine leaks in casing, tubing or packer.

The tubing head and tubing hanger: This is the component, which sits on top of the wellhead and

serves as the main support for the production tubing

The Christmas tree Master gate valve, a pressure gauge, a wing valve, a swab

valve and a choke Downhole Safety Valve:


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Christmas Tree

The set of valves, spools and fittings connected to the top of a wellto direct and control the flow of formation fluids from the well

Christmas tree. Christmas trees are found in a wide range of sizesand configurations, depending on the type and productioncharacteristics of the well. In each case, the Christmas treeprovides primary and back-up control facilities for normal

production and wellbore shut-in. The Christmas tree alsoincorporates facilities to enable safe access for well interventionoperations such as slickline, electric wireline or coiled tubing.

The primary function of a tree is to control the flow into or out ofthe well, usually oil or gas. A tree often provides numerousadditional functions including chemical injection points, wellintervention means, pressure relief means (eg annulus vent), treeand well monitoring points

The CONTROL SYSTEM attached to the tree controls the downholesafety valve, while the tree acts as an attachment and conduitmeans of the control system to the downhole safety valve.

Subsea trees are available in either Vertical or Horizontalconfigurations with further speciality available such as Dual Bore,Monobore, concentric, Drill-Through, Mudline, Guidlineless orGuideline


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Drive Mechanisms

A good reservoir will have sufficientpressure to push hydrocarbons to thesurface by itself. However as thepressure is released the productionwill drop. To maintain that productionvarious methods are employed.

1.) Gas Injection 2.) Water Injection


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Water Injection

The water injection method used in oilproduction is where water is injected backinto the reservoir usually to increasepressure and thereby stimulate production

Water is injected for two reasons: 1. Forpressure support of the reservoir (alsoknown as voidage replacement). 2. Tosweep or displace the oil from thereservoir, and push it towards an oil

production well. [2] Water Sources: 1.) Sea Water 2.) Produced

Water


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Water Injection Process

Water is passed through filters to remove impurities. Thefiltration is up to 2 micrometers in various steps. Sand Filtration Salts Filtration

De-oxygenation

From the filters water is fed to de-oxygenation tower.Oxygen is removed to minimize corrosion or any bacterialgrown.

De-oxygenation tower brings the injection water intocontact with a dry gas stream. The filtered water drops intothe de-oxygenation tower, splashing onto a series of trays,causing dissolved oxygen to be lost to the gas stream.

As a backup, an alternate method is to add SodiumBisulfate to water source.

High Pressure, High Flow pumps are used to inject water intothe reservoir. They fill the bottom of the reservoir to push theoil towards the well.


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Well Test

Rizwan Saeed


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Artificial lift

Plunger Lift

Rod Pumps

Downhole pumps

ElectricalSubmersible pumps


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Production Separator

The well stream consists of crude oil, gas,condensates, water and various contaminants. Thepurpose of the separators is to split the flow intodesirable fractions.

Gravity type production separator [1]

Various Stages of separation can be designeddepending upon hydrocarbons and condensateformation in wells


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Production Separator

Slug catcher will reduce the effect of large gasbubbles and liquid plugs.

Oil Level Control

Gas Pressure Control

Prevent Blowout in Separator Prevent High Pressure in Vessel

PIT

LIT


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Electrostatic Desalter

A desalter is used to removeunacceptable amount of salts in theseparated oil.

Various stages of desalters can beused depending upon the amount ofsalts in oil.

The electrostatic desalters useelectrodes to separate salts ofsodium, calcium and magnesium.


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Desalter Operation

Fresh water addition provides dilution

Coalescence to promote droplet growth

Phase separation to remove contaminants

Combined AC/DC fields provide bettercoalescence and electrolytic nature fordesalting.


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Free Water Knockout

A vertical or horizontal separator used mainly to removeany free water that can cause problems such as corrosionand formation of hydrates or tight emulsions, which aredifficult to break

A free-water knockout is commonly called a three-phaseseparator because it can separate gas, oil and free water.The liquids that are discharged from the free-waterknockout are further treated in vessels called treaters.Free-water knockout is abbreviated as FWKO.


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Surge Tank

Surge tank is a vessel placed in aflowline through which liquids orgases are flowed to neutralize sudden

pressure surges.

A surge tank is usually a large vessel.

It is located downstream of the

Production Separators, Treaters,FWKO and desalters.

It is located upstream of Shipping

pumps.


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Charge Pumps and Shipping Pumps

Charge pumps are located in downstreamof Production separators.

Charge pumps are usually upstream ofCrude oil heaters

Shipping pumps pump oil from oneplatform to another platform.

Shipping pumps pump oil from surge tanksthrough long distance or short distance

pipe lines from offshore/on shore platformsto oil storage facilities. Back pressure control is required on

shipping pumps for maximum efficiency.


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Metering Skids

Orifice plate Meters

Rotary Meters

Ultrasonic meters

A metering skid isdivided into severallines in parallel toprovide accurateand redundantmetering


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GS Process GAS Flow

Wells ReceiverManifold

ProductionSeparators

FlareScrubber

Over Pressure Protection(Desalters, FWNO, Surge Tank, e.t.c.)

GasComp

Metering

LP GasLift


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Flare/Vent Scrubber

A scrubber is designed to remove small fractions ofliquid from gas

A vent scrubber is a two phase separator designed toremove liquid from the relieving fluids before the gasis flared or vented. The liquid is returned to the

process. Incase of GSN the liquid from flare scrubber is fed

back to Surge tank for shipping. A pipe that releases gas to atmosphere is called vent.

If the gas is burned at the tip of vent it is called aflare.

Applicable air pollution control regulations must bemet when venting. Flaring should be done whenreleasing H2S to atmosphere.


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Gas supply to Utilities

ProductionSeparator

GasComp

Stage 1

GasComp

Stage 2

GasComp

Stage 3

FilterSeparator

GlycolContactor

HP FUELGAS SCRUB

GASLIFT

MP FUELGAS SCRUB

MP GASCONDITIONING

FUELGAS


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Gas Compression

Gas passes through following equipmentfor compression:

Cyclotube Separator

Separator Filters

Heat Exchanger

Turbine Compressor


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Temp Control and Dehydration

Methanol is injected in flow lines toprevent Hydrate formation andprevent corrosion. Hydrates form and

freeze to hydrate ice that may upsetprocess and damage equipment andpipes.

For normal risers, hydrates form only

when production stops and the tempstarts to drop.


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Glycol Dehydration System

GlycolContactor

Tower

Gas Inlet

Gas outlet

HeatExchanger

Pumps

GlycolReboiler

Condensateseparator

HeatExchanger

HeatExchanger


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Associated Processes

Gas Injection

Gas Compressors

Glycol Unit Reboiler

Heat Exchanger

Methanol Injection

Water Injection


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Misc Operations

Oil sampling unit

Refined oil/water separation (Wemco)

Fuel gas supply for generators

Water treatment

Air compressors for platform air

supply


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Oil Sampling

An Oil Sampler is used to check thequality of Oil.

Usually an Oil Sampler is installedupstream of shipping pumps.

A common oil sampler consist of ansampling tank, injector and a pump.

The sampling time depends uponRate of Flow in the shipping line.

Welker Sampler


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Welker Sampler


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WEMCO


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Water Treatment


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References

1. Oil and gas Production Handbook

2. www.Wikipedia.org

3. Petroleum and Natural Gas Engineering

Handbook4. Design of Oil Handling System and

Facilities

5. Surface production operations

6. http://www.natcogroup.com/Content.asp

7. http://www.glossary.oilfield.slb.com/
http://www.wikipedia.org/http://www.natcogroup.com/Content.asphttp://www.natcogroup.com/Content.asphttp://www.wikipedia.org/

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