Table of Contents
What is Petroleum Geology?
Petroleum geology is a specific arena of geosciences that addresses the origin, distribution, exploration, development, and production of oil and natural gas resources.
Petroleum geoscientists comprise many specialities such as petroleum geologists, exploration geophysicists, geochemists, sedimentary geologists, structural geologists, and palaeontologists.
Analysis of Petroleum Geology
Petroleum geology involves the analysis of:
1) Source rocks that are ironic in organic matter – the source of oil and natural gas;
2) Geological constructions and stratigraphic layers that permit accumulations of petroleum to the procedure in the subsurface (traps and seals);
3) And also, The characteristics of porous subsurface pillar formations that stock oil and natural gas (petroleum reservoirs).
Petroleum geology is thrilling because one uses many different types of data such as rock cores from wells, well logs that deliver information about the rock and fluid properties.
And 3D seismic images, all of which use to develop 2D and 3D maps and replicas of the subsurface and the distribution of petroleum resources and calculate volumes of oil and natural gas that exist in distinct areas (petroleum assets estimates).
Why is Petroleum Geology at OU Important?
The School of Geosciences, Mewbourne School of Petroleum and Geological Engineering, and Oklahoma Geological Survey have factually had strong agendas and a global reputation in petroleum research and education spanning more than 100 years.
E.g., the world’s first School of Petroleum Geology found at OU, development of exploration seismology.
Petroleum geology is a significant part of the School of Geosciences and OU:
- Many students attend OU to follow petroleum geoscience and engineering education to prepare for careers in the petroleum industry, government, and academia.
- Students in the School of Geosciences attain the education and skills necessary for rewarding careers.
- The curriculum is told by exceptional faculty, many of whom have valuable industry experience that incorporates active learning through laboratory- and field-based experiences.
- The petroleum industry traditionally provides substantial funding critical for the School’s operations, scholarships, and research. Many of our alumni are kind givers to the School and the University.
- Alumni provision for the School is one of the uppermost for any academic unit in the University. Students have many schmoosing opportunities with industry professionals that visit a site and through local petroleum companies.
- Given our reputation, forte in petroleum geoscience and engineering, and excellence of our students, numerous leading energy companies (15-30+) employee at OU each year. Many students continue in Oklahoma and contribute to our local cheap and communities.
- And also, OU is in the emotion of a major petroleum province and surrounded by several key lively petroleum theatres. Secretarial for 10% of the State’s gross income, petroleum is the support of Oklahoma’s cheap.
- Oklahoma positions 4th in crude oil and 3rd in natural gas manufacture in the U.S. OU is near to many localities for fascinating geology field trips and site visits to petroleum business offices and laboratories.
Major Subdisciplines in Petroleum Geology
Several major subdisciplines are in petroleum geology specifically to study the seven key elements deliberated above.
1. Source Rock Analysis
- In terms of basis rock analysis, several facts need to establish. Firstly, the question of whether there is any source rock in the area must answer.
- Delineation and identification of potential source rocks depend on the local stratigraphy, palaeogeography and sedimentology to determine the likelihood of organic-rich sediments having deposit in the past.
- If the likelihood of there being a source rock think to be high, the next matter to speech is the state of thermal maturity of the source and the timing of maturation.
- The maturation of source rocks (see diagenesis and fossil fuels) depends strongly on temperature, such that the majority of oil generation occurs in the 60° to 120 °C range.
- Gas generation twitches at similar temperatures but may continue up beyond this range, perhaps as high as 200 °C. Therefore, to determine the likelihood of oil/gas generation, the thermal history of the source rock must calculate.
- This is performed with a mixture of geochemical analysis of the source rock (to control the type of kerogens present and their maturing characteristics).
- And also, basin modelling approaches, such as back-stripping, model the thermal incline in the sedimentary column.
2. Basin Analysis
- Full-scale basin analysis is usually carried out before defining leads and prospects for future drilling.
- This study challenges the petroleum system and studies source rock (presence and quality), burial past; maturation (timing and volumes); migration and focus.
- And also potential regional seals and main reservoir units (that define carrier beds).
- All these elements used to investigate where potential hydrocarbons might migrate towards. Traps and potential principals and prospects then define the area likely to have received hydrocarbons.
3. Exploration Stage
- Although a sink analysis is usually part of the first study, a company conducts it before moving into an area for future exploration.
- And also, it is sometimes completed during the exploration phase.
- Exploration geology comprises all the activities and assignments necessary for finding new hydrocarbon occurrence.
- Usually, seismic (or 3D seismic) educations are shot, and old exploration data (seismic lines, well logs, reports) expand upon the new studies.
- Sometimes gravity and magnetic studies conduct, and oil seeps and spills are mapped to find potential areas for hydrocarbon occurrences.
- As soon as an exploration finds a significant hydrocarbon occurrence- or wildcat-well the appraisal stage starts.
4. Appraisal Stage
- The Appraisal stage use to define the extent of the discovery. Hydrocarbon reservoir properties, connectivity, hydrocarbon kind and gas-oil and oil-water contacts determine possible recoverable volumes.
- This usually does by drilling more appraisal wells around the initial exploration well. Production tests may also give insight into reservoir pressures and connectivity.
- And also, the geochemical and petrophysical analysis gives info on the type (viscosity, chemistry, API, carbon content, etc.) of the hydrocarbon. And also the nature of the reservoir (porosity, permeability, etc.).
5. Production Stage
- After a hydrocarbon, the occurrence has been discovered, and appraisal indicates commercial finds the production stage initiate.
- This stage focuses on removing the hydrocarbons in a controlled way (without damaging the formation, within favourable retail volumes, etc.).
- And also, production wells drilled and complete in strategic positions. 3D seismic is usually available by this phase to target shafts precisely for optimal recovery.
- Sometimes improved recovery (steam injection, pumps, etc.) is used to extract more hydrocarbons or improve abandoned fields.
6. Reservoir Analysis
- The existence of a tank rock (typically, sandstones and fractured limestones) determine through a combination of regional studies (i.e. analysis of other wells in the area), stratigraphy and sedimentology (to quantify the pattern and extent of sedimentation) and seismic interpretation.
- Once a potential hydrocarbon reservoir identifies, the key physical characteristics of a pool of interest to a hydrocarbon explorationist are its bulk rock capacity, net-to-gross ratio, porosity and penetrability.
- Bulk rock volume, or the gross rock capacity of rock above any hydrocarbon-water contact, determine by charting and correlating sedimentary packages.
- The net-to-gross ratio, typically projected from analogues and wireline logs, use to compute the sedimentary packages that cover reservoir rocks.
- The bulk rock volume increased by the net-to-gross ratio gives the net rock volume of the tank. The net rock capacity multiplied by porosity gives the total hydrocarbon hole volume, i.e. the power within the alluvial package that fluids (importantly, hydrocarbons and water) can occupy.
- The summary of these volumes (see STOIIP and GIIP) for a given exploration view will let travellers and commercial forecasters control whether an option is financially viable.
- Traditionally, porosity and permeability determine through the study of drilling samples, analysis of scores obtained from the wellbore, examination of contiguous parts of the reservoir that outcrop at the surface (see, e.g. Guerriero et al., 2009, 2011, in references below), and by the technique of formation evaluation utilizing wireline tools approved down the well itself.
- Modern advances in seismic data gaining and processing have meant that seismic qualities of subsurface rocks are readily obtainable.
- And also, it can use to infer the physical/sedimentary properties of the stones themselves.
Petroleum geology is the education of origin, occurrence, movement, buildup, and examination of hydrocarbon fuels. And also, it mentions the specific set of geological disciplines applied to the search for hydrocarbons (oil exploration).