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8/14/2019 Introduction to Petroleum Engineering - Lecture 13 Final- Formation Evaluation - Well Logging
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BEng (Hons) Petroleum Engineering
Course:
Introduction To Petroleum Engineering
Instructor
Dr. Tarek Darwich
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Course Outlines: What is Petroleum Engineering?
The Life Cycle of Oil and Gas projects,
Origin, formation and accumulation of Petroleum,
Oil & Gas Exploration,
Appraisal of Oil & Gas Discoveries,
Development of Oil & Gas Discoveries,
Producing Oil & Gas Fields, Transportation of Oil & Gas,
The Petroleum Industry & the Environment,
Petroleum Economics.
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
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Formation Evaluation
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
Formation evaluation is the analysis and interpretation of core data, logdata, well test data, in terms of the nature of the formation andthe fluids content.
The objectives of Formation Evaluation are: To derive lithology and other information on formation characteristics for use in
future exploration, appraisal and development.
To ascertain if commercially producible hydrocarbons are present
Main parameters evaluated
Lithology Rock properties (porosity and permeability)
Fluids types and saturation
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Formation Evaluation in the Exploration Phase
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
In the exploration phase, emphasis is put on welldata with limited information about interwellregions.
Well data results are characterised by largeuncertainties.
Well data include:
Mud logging
Core data (routine and special core analysis)
Well logging (wireline and while drilling Downhole pressure data and fluid sampling
Formation testing
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Well Logging
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
It can be either open-hole or cased-hole logging.
Open-hole logging is performed:
Before setting casing or liner
Several tools can be run together.
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Open-hole Logging Tools
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
Gamma Ray
Lithology identification and correlation
Conductivity/Resistivity
Measures formation resistivity to identify fluid content
Density
Measures porosity and identifies lithology
Neutron
Measures porosity and identifies lithology
Locate gas and fluid contacts
Sonic
Measures acoustic velocity for porosity and identifies lithology
Borehole Seismic
- Recovers Seismic data
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Open-hole Logging Tools
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
Fluid Sampling
Retrieves fluid samples under reservoir conditions
Estimates permeability
Rock sampling
Provides side wall cores
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Well Logging Unit
I ntroduction to Petroleum Engineer ing
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Open-hole Logging Tools
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
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Well Logs
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
http://www.google.co.uk/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=202UW_hQ_npIPM&tbnid=kAbacfcvnOMguM:&ved=0CAUQjRw&url=http%3A%2F%2Flogdigi.com%2Fclient%2Findex.php%3FcPath%3D2&ei=etkdUY69BOGj0QWh-4DYBg&bvm=bv.42553238,d.d2k&psig=AFQjCNHjKRkBpCotmNz6sjlkocSvKlqDMQ&ust=13609971084490098/14/2019 Introduction to Petroleum Engineering - Lecture 13 Final- Formation Evaluation - Well Logging
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Openhole Log Evaluation
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
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Openhole Log Evaluation
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
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Openhole Log Evaluation
I ntroduction to Petroleum Engineer ing
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Clastic and Carbonate Rocks
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
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Clastic and Carbonate Rocks
Relative Abundance
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
Mudstone
(Siltstone
and shale;clastic)
~75%
Sandstone
and conglomerate
(clastic)
~11%Limestone and
Dolomite
(carbonate)
~14%
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Rock Matrix and Open Space
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
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Porosity
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
Porosity is defined as the fraction of the rock that is occupied by voids(pores).
Porosity can be measured through core holes and/or openhole wireline logs.
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Porosity Log Types
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
Three main log types: Bulk Density, Sonic and Neutron.
These logs do not measure porosity directly.
To accurately calculate porosity, the analyst must know: Formation Lithology
and fluids in the pore space.
The three porosity logs:
Respond differently to different matrix composition
Respond differently to presence of gas or light oils
Combinations of logs can
Imply composition of matrix
Indicate the type of Hydrocarbon in pores.
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Permeability
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
Permeability is a property of the porous medium and is a measure of thecapacity of the medium to transmit fluids.
It may be also defined as the measure of the fluid conductivity of theparticular material.
Permeability can be determined from Core analysis
Well Test Data
Log Data (Magnetic Resonance Imaging MRI)
D L
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Darcys Law
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
Where Q is the fluid flow rate,
K is the permeability of the rock the fluid is flowing through,
U is the viscosity of the fluid
A is the cross sectional area
L is the distance over which the fluid is flowing Delta P is the pressure drop
Darcys Law
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Fluid Saturation
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
The saturation of any given fluid in a pore space is the ratio of the volume ofthat fluid to the total volume of the pore space.
Irreducible water saturation is the minimum water saturation obtainable in arock
Water is usually the wettingfluid in oil and gas reservoirs.
Water-wet reservoir Oil-wet reservoir
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Initial Fluids Saturation
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
Pores are initially saturated with water (Sw=1.0)
Hydrocarbons (oil and/or gas) migrate up-dip into a trap due to havingdensity less than water density (gravity force)
Hydrocarbons are distributed such gravity and capillary forces are inequilibrium.
Minimum initial water saturation remains in hydrocarbon zone even afteraccumulation occurs.
When a reservoir is drilled, some of the fluids near the wellbore are pushedaway and the zone is invaded by the drilling fluids.
If hydrocarbons were present, the water saturation after invasion will behigher than the original water saturation.
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Fluids Saturation Changes
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
A shallow resistivity log will see the invaded zone water saturation. A deeperresistivity log will see the original formation water saturation as long asinvasion was not too deep.
Production of oil and gas will change the fluids saturation. The amount of
change varies with the driving mechanism (Solution-gas drive, gas expansiondrive, water drive, .)
Reservoir monitoring (by running special cased-hole logging) is used toassess the changes of water saturation over time.
Changes in the position of the fluids contacts may lead to a work-over of thewell to restrict the perforated interval to reduce water and/or gas production.
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Fluids Saturation Measurements
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
Direct Measurements:
Core Analysis
Indirect Measurements:
Well log analysis (conductivity/resistivity logs)
Capillary pressure measurements
Core measurements may be affected by flushing of cores by filtrate fromdrilling fluids.
Core measurements may also be impacted by changes in pressure and
temperatures as core sample is brought from reservoir conditions to surfaceconditions.
Reservoir monitoring (by running special cased-hole logging) is used toassess the changes of water saturation over time.
-
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Maximum Water Saturation for Oil & Gas Production
I ntroduction to Petroleum Engineer ing
Year 2012 - 2013
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Fluids Saturation and Resistivities
I ntroduction to Petroleum Engineer ing
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Fluids Saturation and Resistivities
I ntroduction to Petroleum Engineer ing
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Examples of Log Data in a Discovery Well
I ntroduction to Petroleum Engineer ing
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Example of Log Data in a Discovery Well
I ntroduction to Petroleum Engineer ing
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