Exploratio n & Production 101 Susan M. Landon IPAMS 2004
Jan 19, 2016
Exploration&
Production 101
Susan M. Landon
IPAMS
2004
How do we pick the spot for that wildcat well?!?
OBJECTIVES OFPETROLEUM GEOLOGY
• Find and Effectively Produce Oil and Natural Gas
• Improve Predictability
• Reduce Risk
GEOLOGICAL REQUIREMENTS FORHYDROCARBON ACCUMULATIONS
Source Rock Migration Path Reservoir Rock Trap Timing
• Petroleum: a natural yellow-to-blackflammable liquid hydrocarbon found beneath the earth’s surface
• Hydrocarbon:an organic compoundmade up of carbon and hydrogen atoms
What is Petroleum?
What are Hydrocarbons?
Mixtures of hydrogen and carbon atoms with various impurities like sulfur, oxygen, etc.
Hydrocarbon Composition
Carbon + Hydrogen = HydrocarbonAtoms Atoms Molecules
HC + H = H C H
H
Methane gas CH4
simplest
hydrocarbon molecule
Gas Composition
Methane
Ethane
Propane
Butane
CH4
C2H6
C3H8
C4H10
H
C HH
H
C
H H
H
H
C
H
H
H
C
H H
H C
H
HC
H
H
H
C
H H
H C
H
H
C
H
H
C
H
H
The Alphabet Game
LNG = Liquefied Natural Gas
LPG = Liquefied Petroleum Gas
NGL = Natural Gas Liquids
Origin of Hydrocarbons
Generated from organic matter preserved in the sediments
As sediments are subjected to higher temperatures with increasing burial, the organic matter is simplified to molecules of carbon and hydrogen with some impurities
Quality of Source Rock
• Quality of a source rock (how much hydrocarbon can the organic matter generate) is measured by the amount of organic carbon present in the rock – Total Organic Carbon– 1% or more TOC is considered poor– 3 to 5% or greater is considered a good
source rock
Type of Organic Matter
Plant material tends to generate gas
Algal and animal material (amorphous organicmatter) tends to generate oil
Oil can be cracked to gas (just like in a refinery)when it is subjected to high enoughtemperatures
RESERVOIR ROCKPorosity
percent by volume of pore space in the rock – how much fluid or gas will fit between the
grains(%)
Permeability measure of the degree of difficulty the fluid or
gas has in moving through the rock(darcies or millidarcies)
Types of Porosity
Intergranular
Dissolution
Fracture
Clays depositedon grains creating
microporosity
Oil-stained Thin SectionWhite Pine Mine - Wisconsin
Migration of Oil and Gas
Trap
Caprock or Seal
Types of Hydrocarbon Traps
• Structural
• Stratigraphic
• Combination
• Unconventional (basin-centered, coalbed methane, shale gas)
Structural Traps
Oil Seeps
Source Rock
Monroe and Wicander, 1992
Fault TrapAnticlinal Trap
Oil
field
Oil
field
Stratigraphic Traps
Source Rock
Unconformity Trap
Combination Trap
/Seal
/Seal
TIMING…..
Traps must be in place before oil and gas begin to migrate.
Basin-Centered (Continuous)Trap
An “unconventional trap”
- regional
- diffuse boundaries
- low permeability reservoir
- frequently abnormally pressured
- closely associated with source rocks
Types of Data
• LIBRARY!
What has been done before?
• Field work
• Information from Drilling
Field Geology
Drilling
Most of the data usedto find and efficientlyproduce hydrocarbonscomes from wellsthat have been drilled.
What data do we need andhow do we integrate andinterpret the data todetermine where to drill?
Data Collected From Wells
• Drilling time – record of how fast the bit is cutting downward
• Mud Log - measured gas released by drilling
• Cuttings – chips of rock cut by the bit and described by the well site geologist
• Core – special bit cuts a cylinder of rock
• Drill Stem Tests – samples fluid and measures pressure
• Wireline Logs
Wireline Logging
Computer
Logs measure physicalcharacteristics of therocks drilled. A tool islowered down the wellbore and, as it is pulledback to the surface, itmeasures a property likenatural radioactivity.
RIG
Typesof Logs
1 2 Rock/fluid 3 4 5
1. Gamma Ray
2. Caliper (dashed)(diameter of hole)
3. Spontaneous Potential
4. Electrical Resistivity
5. Density
6. Sonic
Log Response to Rock
Beach Sand
Channelsand
Density decreasesPorosity increases
From Hancock, 1992
GR (API)
Neutron Porosity (%)
Bulk Density (gm/cc)
Formation Image Log
Fracture
Bedding
Formation Image Log
Horizontal Well Bore
Bedding Planes
Types of Maps
• Topographic maps - variation in elevation• Geologic maps - distribution of geologic
features• Structure maps - variation in the shape of a
subsurface layer• Isopach maps - equal thickness• Contour map of any distribution of values• Anything else you can think of!
Structure Map
•Show the shape of a subsurface rock layer, usually with reference to sea level
•Show structural features such as folds and faults
Map View ofRiver Meander
Cross Section
Point Bars
Point Bar
Fluvial Deposition
Gra
in s
ize
dec
reas
ing
up
war
ds
Erosion
Coyote CreekField
Berg, 1986
Isopach Map
Channel Sandstone Reservoir
0
100’
Berg, 1986
Cross Section
Structural cross section - shows present daygeometry of the rock layers in the subsurface.
Ranger Formation, Wilmington Field, CA
From Morton-Thompson and Arnold, 1992
Cross Section
Stratigraphic cross section - provides a picture of the history of deposition and structural development. An internal boundary is the datum.
Ranger Formation, Wilmington Field, CA
From Morton-Thompson and Arnold, 1992
Geophysical Methods
• Gravity
• Magnetics
• Seismic
• Other techniques
Technological Advancements:An Opportunity
Seismic Profile
1. Signal emitted by vibrator truck
2. Reflected waves received by geophones
3. Data transmitted to laboratory truck
Synthesis
http://www.elf.fr/odyssee/us/depot/204.htm (Thanks to Jane Woodward)
2D
3D
4D
SeismicLine
1
Shot Points
Reflections
Formations
REEF
3-D Seismic
Courtesy of ExxonMobil
3-D Seismic
A time slice from a 3-Dseismic program in northTexas - like a map.
Can you interpret the environment of deposition?
From the AAPG Explorer
Now we have decided where we would like to drill. How do we obtain
permission to drill for and (hopefully) produce
hydrocarbons?
Leasing – Land OwnershipUnited States
• Private - 2/3 of US is in private ownership• State
– Onshore– Offshore
• Federal– Onshore (BLM, Forest Service, DoD, etc.)
• Most Federal land is located west of the Mississippi
– Offshore (MMS)
Basic Land Questions
• Where is the land located?
• Who owns it?
• Is the owner's title clear?
• What rights are needed?
Where is the land located?
• There are two basic types of land surveys– Metes and bounds (early surveys)– Rectangular survey
• Most of the western U.S. is described with by the rectangular survey
Rectangular Survey System
Typical Section640 acres
ONEMILE
SE/4SE/4 40 ac
W/2
320 acONEMILE
NE/4
160 ac
6
Public Owners• federal government• state governments, counties,
cities or towns• school systems
Private Owners individuals
companies
institutions
Who Owns the Land?