Exploration & Production 101 Susan M. Landon IPAMS 2004

How do we pick the spot for that wildcat well?!?

OBJECTIVES OF PETROLEUM GEOLOGY Find and Effectively Produce Oil and Natural Gas Improve Predictability Reduce Risk

GEOLOGICAL REQUIREMENTS FOR HYDROCARBON ACCUMULATIONS  Source Rock  Migration Path  Reservoir Rock  Trap  Timing

Petroleum:a natural yellow-to-black flammable liquid hydrocarbon found beneath the earth’s surface Hydrocarbon:an organic compound made 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=Hydrocarbon AtomsAtomsMolecules H C+H=H C H H Methane gas CH 4 simplest hydrocarbon molecule

Gas Composition Methane Ethane Propane Butane CH4CH4 C2H6C2H6 C3H8C3H8 C 4 H 10 H CHH H C HH H H C H H H C HH H C H HC H H H C HH 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 organic matter) tends to generate oil Oil can be cracked to gas (just like in a refinery) when it is subjected to high enough temperatures

RESERVOIR ROCK Porosity 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 deposited on grains creating microporosity

Oil-stained Thin Section White 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 Trap Anticlinal Trap Oil field

Stratigraphic Traps Source Rock Unconformity Trap

Combination Trap /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 used to find and efficiently produce hydrocarbons comes from wells that have been drilled. What data do we need and how do we integrate and interpret the data to determine 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 physical characteristics of the rocks drilled. A tool is lowered down the well bore and, as it is pulled back to the surface, it measures a property like natural radioactivity. RIG

Types of Logs 1 2 Rock/fluid Gamma Ray 2.Caliper (dashed) (diameter of hole) 3.Spontaneous Potential 4.Electrical Resistivity 5.Density 6.Sonic

Log Response to Rock Beach Sand Channel sand Density decreases Porosity 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 of River Meander Cross Section Point Bars Point Bar Fluvial Deposition Grain size decreasing upwards Erosion

Coyote Creek Field Berg, 1986 Isopach Map

Channel Sandstone Reservoir 0 100’ Berg, 1986

Cross Section Structural cross section - shows present day geometry 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 (Thanks to Jane Woodward) 2D 3D 4D

Seismic Line 1 Shot Points Reflections Formations REEF

3-D Seismic Courtesy of ExxonMobil

3-D Seismic A time slice from a 3-D seismic program in north Texas - 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 Ownership United 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 Section 640 acres ONE MILE SE/4 SE/4 40 ac W/2 320 ac ONE MILE 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?