Oil and Gas in Saskatchewan
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Commercial crude was first discovered in 1944.
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By 2006, more than 7,100 wells had been drilled.
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2,339 wells were drilled in 2006 (second highest number on record)
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First commercial natural gas well was drilled in 1934.
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By the end of 2006 there were 18,700 wells.
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SK is third in Canada in natural gas production.
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In 2006, more than 38% of SK’s export value came from oil and gas, the province’s most
important sector.
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SK produces 20% of Canada’s oil and gas (second after Alberta).
Some numbers on Oil and Gas in SK
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In 2006 SK produced a record 24.84 MMm3 (156.3 MMbbl) of oil.
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$300 million was invested into the gas filed in 2006.
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In 2006/07 SK realized $179.6 million from natural gas royalties and taxes.
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Oil used: 18% in province, 66% exported to US, 16% is sold in eastern Canada.
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SK has an estimated 25 billion barrels of heavy oil in place.
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Overview of Stages in Oil Processing
Discovering Oil Reservoir:
Drilling a well:
Completing a well:
Well Stimulation:
Production:
1. Flowing wells
2. Artificial lift: Some type of mechanical or artificial means is necessary to bring the oil
from reservoir to the surface. The most common methods are: Beam pumping,
submersible pumping, gas lift and hydraulic pumping.
Production unit:
Fractionation:
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Some links:
Petroleum Society (Canadian Inst. of Mining, Metallurgy and Petrol.): http://www.petsoc.org/
Oil and Gas Resources (Government of SK): http://www.ir.gov.sk.ca/oilgas
Alberta Energy and Utilities Board: http://www.eub.ca
Society of Petroleum Engineers (SPE): http://www.spe.org/
SPE Canadian section: http://www.speca.ca/
American Petroleum Institute (API): http://www.api.org/
European Petroleum Industry Association: http://www.api.org/
Gas Processors Association: http://www.gasprocessors.com/
Organization of the Petroleum Exporting Countries (OPEC): http://www.opec.com/
International Energy Association: http://www.iea.org/
Journal of Canadian Petroleum Technology: http://www.petsoc.org/jcpt.html
Oil and Gas Journal: http://www.ogj.com/index.cfm
Schlumberger Oilfield Glossary: http://www.glossary.oilfield.slb.com/default.cfm
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Introduction
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Petroleum Geology
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Origin of solar system
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Geological cycle
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Geological periods
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Types of reservoir rocks
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Main elements of reservoirs
Origins of Petroleum
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Organic material deposition
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Migration/conversion
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Entrapment
- Petroleum Engineering
- Formation Evaluation
-Drilling Engineering
-Reservoir Engineering
-Production Engineering
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Petroleum geology:
The Nebular Hypothesis
Evidence in support of Nebular Hypothesis
Geological Cycle
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Types of Reservoir Rocks
Sedimentary: Formed by the cementation of sediment grains/particles on or near surface at ordinary
temperature.
Igneous: Formed by solidification of molten minerals/materials.
Metamorphic: Formed within earth’s crust by transformation of other rocks ant high pressure and
temperature.
Main elements of a reservoir
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Source rock (source of hydrocarbons)
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Reservoir trap (structural or stratigraphic)
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Reservoir seal (to contain hydrocarbons within reservoir trap)
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Quality of reservoir rock (reasonable porosity and permeability)
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Origin of petroleum:
Petroleum reservoirs are created through three sequential steps:
deposition, migration/conversion and entrapment .
A) Organic material deposition:
Petroleum originates mainly from plankton (single cell free floating plant). This organic material
must be buried under a sediment or silt. The silt guards the organic material from aerobic
consumption. Deposition process normally takes place in the river deltas or between shores
and reefs (stagnant flow zone). The organic material and sediment form a source bed which is
required for the remaining steps in the process. This is often called “black shale” or
“sedimentary rock”.
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B) Migration/Conversion:
For a reservoir to be formed, a porous rock must form above the source bed rock.
Sandstone (larger grains of sand compared to silt)
Dolomite (marine shales first form limestone CaCO3 and through substitution of magnesium
and possibly acid attack the porous dolomite forms.)
The organic material migrates from the source bed through the porous rock by two
mechanisms: Pressure and Buoyancy.
PRESSURE:
The pressure on the source bed is generated by the overburden. Initially the organic material is
typically converted into shale. Under pressure of the overburden, water is expelled from the
source bed and it migrates into porous rock. Organic hydrocarbons follow the same path as
water. The series of events involved in the transformation of organics into petroleum is not well
known. This conversion takes place during both the initial migration (pressure related) and
during the period that the organic material is retained in the porous rock.
Temperature plays a major role in the conversion. T in the porous rock is determined by the
average surface T and the geothermal gradient. In western Canada these values are: 0 °C and
0.038 °C/m. Generation of crude oil is promoted at temperature between 50 °C (1300 m) and
175 °C (4600 m).
For depths less than 1300 m petroleum tends to be selectively degraded by bacteria where the
lower density components are consumed and the higher density fluids remain (e.g. Bitumen
within the Oilsands). For depths greater than 4600 m, the petroleum undergoes thermal
degradation to form gas.
The absolute pressure exerted on the source and reservoir rock increases with the depth of
overburden above the layers. Although the absolute pressure is the driving force for the
primary migration, it does not appear to be an important parameter in the chemistry of
converting organic material to petroleum since a similar crude oil is obtained at a wide range of
well depths at different locations in the world.
BUOYANCY:
Following the primary migration and conversion, small droplets of petroleum coalesce to form
larger volumes. At this point a secondary migration occurs which is driven by buoyant forces.
Surrounding water pushes the oil and gas, which have a lower density, upward through the
reservoir rock layer.
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C) Entrapment:
Entrapment occurs when the petroleum reaches an impermeable layer where no further
migration can occur. This rock layer is known as a trap. There are three types of traps:
structural, stratigraphic, and combination.
1) STRUCTURAL TRAPS:
Structural traps are formed by folding (Anticline) or faulting (normal or thrust) or salt dame.
Folding occurs from compression and tension in the earth’s crust including uplifts caused by salt
or shale. The inverted U-shape of the fold (the anticline) results in a trap where the upper layer
(the cap rock) is impermeable to the oil.
Fault traps result from shifting and displacement along a fault line, which places a reservoir
layer adjacent to an impermeable layer.
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2) Strarigraphical TRAPS:
Stratigraphic traps are formed by a change in the character of the reservoir rock (less
permeable) or a change in the deposition environment where an impermeable layer is
deposited around the reservoir rock.
Three common Stratigraphic traps: Pinch out, Reef, and Unconformity
Examples:
The layering must have both a vertical and lateral aspect to act as a trap. This can occur with
offshore sand bars, channel filled stream beds, or reefs.
Unconformity results from a non-lateral sedimentation, followed by lateral erosion and
sedimentation of an impermeable layer.
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3) Combination traps:
Combination traps have characteristics of both structural and stratigraphic traps. A trap is
created due to a salt dome or salt plug moving upward. As the salt dome pushes upward
through the sedimentary layers (stratigraphic component), it causes folding and faulting
(structural component). This results in formation of combination traps.
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Differential entrapment:
1. During initial migration, oil fills the interconnected reef traps at different elevations.
2. 2. Sometime later, gas may form in source rock and move upward to displace some of
the oil.
Based on largest oil fields:
Age of Fields:
8 % Paleozoic age (225 to 570 Million years)
63 % Mesozoic age (65 to 225 Million years)
29 % Tertiary and Pleistocene age (0.010 to 65 Million years)
Types of Traps:
Structural (Anticline) Traps: 89 %
[result of folding/faulting]
Stratigraphic: 9 %
[result of sedimentation]
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Fault and Combination: 2 %
Quality of reservoir rock:
Porosity:
Permeability:
Petroleum Engineering
Petroleum engineering is divided into four main disciplines. There is a certain degree of overlap
between the disciplines.
1)
2)
3)
4)
Formation Evaluation
Drilling Engineering
Reservoir Engineering
Production Engineering
1) Formation Evaluation:
Objective:
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Information from the formation evaluation will determine the extent of the reservoir and
provide an estimate of the amount of oil available and the difficulty in obtaining the oil. The
preliminary feasibility of the reservoir can be determined from this information. The results
also guide the work of the other disciplines in determining the most effective method to
produce oil from the field.
2) Drilling Engineering
Objective:
Responsibilities also include the design of networks of horizontal wells. A key concern of the
drilling engineer is to limit the extent of wellbore damage during drilling.
3) Reservoir Engineering
Objective:
This work involves modelling the entire oil field. There are a number of modeling and
simulation software in the market.
4) Production Engineering
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Objective:
The production engineer must obtain the maximum production from one or more wells at the
minimum cost.
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