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Topic outline

 

  • Time: 12 hours
    Level: Intermediate

 
 

Introduction

  • Introduction Resource
  • Oil and gas seeps have been known since earliest recorded history. Sticky black asphalt was used by the Babylonians as a roofing material, the ancient Egyptians used it to preserve their dead, and Noah...
 

1 The chemistry of petroleum – what is petroleum?

 

2 Key ingredients for petroleum accumulation

  • 2.1 Petroleum charge Resource
  • There are several ‘ingredients’ or geological conditions that are prerequisites for every subsurface accumulation of petroleum. They are petroleum charge , reservoirs, seals and traps. We will look at...
  • 2.1 Petroleum charge (continued) Resource
  • The process of biological, physical and chemical alteration of kerogen into petroleum is known as maturation. Source rocks that experience the right conditions for these processes and can generate petroleum...
  • 2.2 Reservoir rocks Resource
  • The properties of a petroleum reservoir rock are very similar to those of an aquifer since both petroleum and water can be contained within and move between its pore spaces and fractures. Sedimentary rocks...
  • 2.3 Seals Resource
  • Above permeable reservoir rocks there must be an impermeable layer (known as a seal or cap rock) to stop migrating petroleum from rising further towards the surface of the Earth. Seals are fine-grained...
  • 2.4 Traps Resource
  • Petroleum that accumulated as a thin layer at the top of an extensive horizontal reservoir would be uneconomic to extract. That is because many wells, each with only a small rate of production and lifetime,...
  • 2.5: Combining the ingredients Resource
  • Having examined the essential ingredients for a petroleum accumulation, this section discusses how knowledge about them is combined to create a petroleum play. This is a particularly useful concept, since...
 

3 Exploring for oil and gas

 

4 Petroleum production

  • 4.1 Appraising the discovery Resource
  • Once quantities of oil or gas have been discovered by exploration drilling, the next step is to carry out an appraisal programme to determine whether the accumulation is worth developing into a producing...
  • 4.2 Development options Resource
  • The approach to field development is as varied as petroleum accumulations themselves, so what follows is a brief summary. Most major petroleum field development projects in the 1990s and early 21st century...
  • 4.3 Production techniques Resource
  • In order to develop offshore fields economically, numerous directional wells radiate out from a single platform or from several sub-sea wellheads to drain a large area of the reservoir. This allows each...
  • 4.4 Getting petroleum ashore Resource
  • Most offshore oil and all offshore gas are transported to shore by pipelines; the safest, most cost-effective and environmentally friendly solution to transporting large volumes of petroleum without interruption....
 

5 Safety and the environment

  • 5.1 Safety issues Resource
  • Safety and the environment have increasingly become matters of prime concern to the petroleum industry. Losses of life, particularly offshore, and large oil spillages increasingly raise outcries and make...
  • 5.2 Environmental management Resource
  • Management of the environmental impact of projects is not only a legislative requirement, but also good business. It is cost effective, provides a competitive advantage, responds to the public demand for...
 

6 Oil and gas reserves

  • 6.1 Estimating reserves Resource
  • Exploration companies need to understand how much petroleum remains to be found in a given area or play before they commit significant expenditure to new ventures. More generally, reserves and their depletion...
  • 6.2 Reserves categories and reporting Resource
  • There are inherent difficulties in estimating petroleum reserves accurately, not only within a given area or play (as described above), but also within a single field. Reserves never equate solely with...
  • 6.3 The global picture Resource
  • The global occurrence of petroleum is very patchy and there are sound geological reasons for this. The most significant is the distribution of continental and oceanic crust, because source rocks, the prerequisite...
  • 6.4 The UK context Resource
  • For the sake of comparison, it is interesting to note that at the end of 2004 the UK had proved reserves of 4.5 billion barrels of oil (611 million toe) and 590 billion m3 of gas. This implied a R/P ratio...
 

7 Non-conventional sources of petroleum

  • 7.1 Oil sands Resource
  • Non-conventional sources of petroleum, such as oil sands, heavy oil and gas hydrates, greatly exceed the world's entire endowment of conventional petroleum. Yet, because of technological, commercial and...
  • 7.2 Gas hydrates Resource
  • The temperature and pressure of the deep oceans are controlled, respectively, by deep, cold currents that move from polar latitudes along the sea floor and by the mass of the overlying water column. Consequently,...
 

8 Unit summary

 

Glossary

 

References and Acknowledgements

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