The Petroleum Production System - Reservoir

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The petroleum reservoir is the first component we examine. As you may already know, a reservoir is a subsurface body of rock which has sufficient porosity and permeability to store and transmit fluids. They may contain oil, natural gas, or both 5.

Contributions

The reservoirs contributions in the petroleum production system are:

• It provides the natural energy used in the initial production of hydrocarbons
• It determines the initial state and properties of reservoir fluid (consider fluid type and quality)
• It determines the ease of fluid flow from the reservoir to the surface (consider permeability)
• It determines the quantity or amount of hydrocarbon (consider porosity/fractures)

Can you spot the similarity of the reservoirs contributions with the purpose of the petroleum production system?

Problem Areas and Solutions

• Low permeability in reservoir rock. Common approaches to produce despite this challenge are 6
  • Hydraulic fracturing/Acidization
  • Deviated (horizontal) well
  • Infill drilling
  • Reservoir management
• Presence of geologic faults and heterogeneity in reservoir rock properties (e.g. permeability). A common approach is to 7
  • Quantitatively describe the degree of heterogeneity using the Dykstra-Parsons permeability variation V or using the Lorenz coefficient L
• Poor and inconsistent estimates of oil and/or gas in-place volumes. A common approaches to solve this challenge is 8
  • Adoption of a standard such as the United Nations Framework Classification for Resources (UNFC)
• Petroleum reservoirs often have a definite amount of natural energy. Common approaches to produce despite this are 1 9 10
  • Artificial Lift
  • Secondary Oil Recovery e.g. Water injection, Steam injection, Gas injection
  • Enhanced Oil Recovery e.g. Chemical flooding, Miscible gas flooding, Thermal recovery
• Presence of abnormally-pressured zones. A common approaches to define these zones is
  • Seismic detection

As you may note from the above, it is essential to conduct a thorough study of the rock formation.

Up next, we will examine the Wellbore.

Standing on Giant’s shoulders (References):

• Tarek Ahmed, in Reservoir Engineering Handbook (Fifth Edition), 2019
• Abdus Satter, Ghulam M. Iqbal, in Reservoir Engineering, 2016
• John Mitchell, in Petroleum Reserves in Question
• Dennis P. Nolan, in Handbook of Fire and Explosion Protection Engineering Principles, 2011
• AAPG Drive mechanisms and recovery
• AAPG Reserves Estimation
• AAPG Petroleum Reservoir Fluid Properties
• AAPG Petroleum Reservoir
• PetroWiki The Petroleum Production System
• Reservoir - Schlumberger Oilfield Glossary
• Primary Recovery - Schlumberger Oilfield Glossary