PNGE 450 EXAM 1 Introduction Flashcards
Formation Evaluation
Covers a very wide range of measurement and analytic techniques
Geophysics:
seismic studies
Geology:
stratigraphy, sedimentology, lithology
Petrophysics
core analysis, log analysis
Drilling Eng.:
mud properties, rock properties
Reservoir Eng.
reservoir limits, storage capacity, economic value, EOR considerations
Production Eng.
fluid type, fluid pressure, completion considerations, productivity, injectivity
Formation Evaluation Methods
- Mud Logging
- Coring/Core Analysis
- MWD/LWD
- Formation Testing
- Openhole Logging
- Cased-hole Logging
Well Logging
Measurement of formation properties vs. depth:
- Rock properties
- Fluid properties
Two types of Well Logging
1) Openhole (before casing)
* Conventional (wireline) logging
* LWD/MWD
2) Cased hole
Interpretation:
- Geology
- Petrophysics/reservoir
- Completion/production
Openhole logs can provide either a direct measurement or a good indication of:
- Porosity, both primary and secondary (fractures and vugs)
- Permeability
- Water saturation and hydrocarbon movability
- Hydrocarbon type (oil, gas)
- Lithology
- Formation dip and structure
- Sedimentary environment
- Travel times of elastic waves in a formation
Cased hole logs can provide
- Flow rates
- Fluid type
- Pressure
- Residual oil saturation
- Cement bond log
Pros
- Provides most abundant data from the formation
- Very reliable
- Provides vertical and lateral (map) variations in rock/fluid properties
- Modest cost
Cons
Indirect measurement
* Depth of investigation
* Vertical resolution
* Nuclear hazards
1912:
Conrad Schlumberger, recorded the
first map of equipotential curves at his estate
near Caen in Normandy, before extending
his surveys to iron mines in the area
9/5/1927:, 1929:
9/5/1927: Measurements were taken from an
electrical sonde at various discrete depths in a 500
meter-deep well in Pechelbronn in the Alsace region
of France.
From Schlumberger
1929: The USA’s first ever well log is performed in Kern
County, California
2 Types of logging cables
- Monoconductor:
- Multiconductor:
* Completion services: perforation, setting packers
* Production logs: flow, Temp.
* Openhole surveys
Openhole Logging Procedure
- Logging truck is anchored about 100 to 200 ft from the well.
- Lower sheave is chained down near the rotary table.
- Upper sheave is suspended from the crown block.
- Logging tool (sonde) is placed on the cat walk.
- The logging cable from the truck winch is passed over the sheaves,
attached to the logging tool string. - Lift the tool to the rig floor.
- Set the depth reference.
- Run the tool to the total depth (TD).
- 300 ft repeat section.
- Run the tool back to TD.
- Complete survey
Openhole Measurements
Passive (Natural Response):
- Caliper
- SP (Spontaneous Potential)
- Gamma Ray: Natural GR, Spectral G
Openhole Measurements
Active (Induced Response):
- Sonic (Acoustic)
- Nuclear: Neutron, Density, photoelectric
- Electric/Electromagnetic: Resistivity, Induction, NMR
Log Presentation
- Header
- Tool info and Remarks
- Tool sketch and description
- Log Curves
- Repeat Section
- Before/After Survey check
Radius (depth) of invasion depends on:
- Formation properties: porosity, permeability
- Pressure difference between mud and formation
- Drilling fluid properties: water/oil based, viscosity
- Time
Mud Filtrate Invasion Terminology
Uninvaded Zone
Rt : Uninvaded formation resistivity (true resistivity)
Rw : Formation water resistivity
Sw : Uninvaded formation water saturation
