ONSHORE OFFSHORE

Onshore Production generallyhas vertical wells exceptwhere access is restricted

Offshore Production generallyhas deviated wells.

There is an increasing trend towardssub surface completions

OIL FIELD DEVELOPMENT

Oil bearinglayers

HORIZONTAL WELLS

Some Reasons for horizontal wells:

To Maximise Reservoir Drainage from a Single WellTo Reduce the Drawdown on the WellTo Produce From Thin Oil Zones close to Water or GasFor Low Permeability ReservoirsTo Maximise the Interception of Orientated Natural Fractures

Horizontal wells cannot be logged by conventional methods.Coiled Tubing or Well Tractors are required.

Typical Well CompletionSwab Valve

Crown Valve

Wing Valve

Production

20 Casing

13 3/8 Casing

9 5/8 Casing

Reservoir A

Perforations PackerEnd Of Tubing (Usually with restricted ID)

An offshore well will usually start with 30 casing. As the well deepens or if there are drilling problems additional strings of 7 and 5 casing may be run .

Cement

Tubing

Tubing Hanger

WELLHEAD

9 5/8 Completions Appox. 25%7 Completions Approx. 60%5 Completions Approx. 15%

The casing is perforated with explosives. Perforationtunnels are made which extend into the formation.

SSD for Circulation

SafetyValve

Reservoir B

Multiple Zone Completions

Zone C

Zone B

Zone A

Single String Dual String

Sliding Side Door (Sleeve Valve)

TubingIn 9 5/8 Casing4.5-5.5In 7 Casing3.5

TubingIn 9 5/8 Casing2.875In 7 Casing2.375

SSDs may be opened andclosed by tools run on

wireline

Dual Completions offermore flexibility such as injecting down one string and producing the other buttubing size is limited.

Short StringLong String

Log in tubing withcontinuous spinners. Log in casing withfullbore spinners.

Dual strings allow production from zonesat very different pressures

Zone D

Nipple for Plug

What makes an oil well flow?A well will flow if the pressure in the wellbore is less than the pressure in the formation.The formations below surface are assumed to be full of water except where gas or oil are present.Hydrostatic Pressure of formation water 0.435 psi/ftHydrostatic Pressure of Oil 0.300 psi/ftHydrostatic Pressure of Gas (under compression) 0.043 psi/ft

Virgin Reservoir

Surface

10,000 ftDownhole

Reservoir Pressure4,350 psi

Wellbore Hydrostatic Pressureof Oil column = 3000 psiHydrostatic Pressure ofGas column = 430 psi

Surface Press. with Oil = 1,350 psiSurface Press. with Gas = 3920 psi

Reservoir Pressure3000 psi

Depleted Reservoir

Surface Press. with Oil = 0 psiSurface Press. with Gas = 2570 psi

Without ArtificialLift as an OIL WELL thiswell would not flow

Artificial lift methods:Downhole Rod PumpedDownhole Electrical PumpGas lift

Surface pressure is formation pressure minus fluid column hydrostatic pressure

Open the wellhead valve andThe well will flow.

Artificial Lift BEAM PUMPNodding Donkey

FluidLevel

TravellingValve

StandingValve

SuckerRod

FluidExit

StripperRubbers

HighPressureInjectionGas

GasLiftMandrels

CompletionFluid

Mixture ofGas andFluidDecreasesHydrostaticPressure ofFluidColumn

FluidExit

GASLIFT

SeSeparator

Weir

Oil Water

Compressor

ElectricSubmersiblePump

Generator

FluidLevel

RetrievablePlug (can bereplaced bylogging plug)

ELECTRICSUBMERSIBLEPUMP

Limitedto verticalwells

ElectricCable

Pins to preventpremature latching

Fishing neckof loggingplug

ESP

Top ofPLTstring

Grapplesized forPLT fishingneck

Extended fishingneck to protectwireline

Seals

No-go

Electric Submersible Pump Logging

Deviated Well Method 1

Go-Devil topush loggingplug downholeand into seat.

Grappletaps loggingplug sealsinto place.

Distancecalculated sothat top ofPLT string isbelow perfswhen grapplehits.

Deviated Well Method 2

Tool Operating Constraints

Normal Temperature Gradient 360 deg F at 20000 ftHigh Temp Gradient 833 deg F at 20,000 ft

Depth, ft

Pressure, psi20,000

0

0 10,000

Normal Pressure Gradient 8700 psi at 20000 ft1.2 g/cc Press Gradient 10,400 psi at 20,000 ft

Depth, ft

Temperature, F20,000

0

0 350

Venezuela, IndonesiaUS Gulf Coast etc

Normal GeothermalGradient

Subsurface conditions have high pressure and temperature.Sondex tools are for the most part designed to operate at up to 15,000 psi and 350 deg F.

The properties of electrical components change with temperature. Some tools can only be calibratedat surface. The electronics of the tools have in built temperature compensation to ensure that a

surface calibration remains valid downhole.

Pressure

Temperature1.2 g/ccGradient

0 1000PRESSURE

-100 100LINE SPEED

-10 10SPINNER

0 2DENSITY

210 235TEMPERATURE

4000 2500FLUID CAPACITANCE

2200

2300

SRO

LubricatorBlow OutProtector

TOOLS MAY BE RUN ON NON CONDUCTING SLICKLINE OR COILED TUBING