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Introduction to the Oil and Gas Industry (The “Oil Patch”) For ‘Executives’ and/or New Employees Glenn R. Power, Senior Geologist 1
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Introduction to the Oil and Gas Industry(The “Oil Patch”)
For ‘Executives’ and/or New Employees
Glenn R. Power, Senior Geologist
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Many ‘executive’ and ‘upper-level’ staff in the Oil and Gas Industry have backgrounds in Business Administration, Finance, Law, Accounting, and fields of study other than Geoscience and Engineering.
Executive staff with a background in Engineering and/or Geoscience is still quite common, nonetheless, there are still high numbers of executive staff who could benefit from a broad overview of basic Geoscience, especially as it pertains to the Oil and Gas Industry.
Purpose
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The broad overview contained in this PowerPoint presentation contains sufficient technical detail for the executive staff who lack a background in Geoscience and/or Engineering and/or for new employees to the industry.
These presentation materials help to ‘familiarize’ those persons with the many aspects of the Oil and Gas Industry, especially with the ‘catch words’ that they will frequently hear in the numerous technical meetings and presentations which they must attend.
Purpose
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Fossil Fuel:Where does oil and gas come from?
Scale:What is big? What is small?
Plate Tectonics:What does it take to ‘move a mountain’?
Geological Time Scale:A thousand years is like a day.
Depositional Environments:How are rocks formed?
Well Correlations:Each new well is another piece of the puzzle.Well data is how we complete the puzzle.
Drilling and Completions:How do we find and produce oil and gas?
Topics of this Presentation
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One of the most difficult concepts that ‘non-technical’ personnel have with comprehending aspects of the oil and gas industry is the time scale involved.
Oil and gas is frequently found in sandstone reservoirs that were once in a beach environment, at or near sea-level.
Typically, over periods of millions of years these ‘beach sands’ get ‘buried’ deep within the earth, frequently to depths of many thousands of meters.
The geologic processes which result in this ‘burial’ can also result in the ‘building’ or ‘uplift’ of mountains.
Therefore, it is not only necessary to address the time scale involved, but the notion of scale itself, from the tiniest microscopic features to the largest mountains.
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Fossil Fuel:Where does oil and gas come from?
Scale:What is big? What is small?
Plate Tectonics:What does it take to ‘move a mountain’?
Geological Time Scale:A thousand years is like a day.
Depositional Environments:How are rocks formed?
Well Correlations:Each new well is another piece of the puzzle.Well data is how we complete the puzzle.
Drilling and Completions:How do we find and produce oil and gas?
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Exploration, discovery, delineation and production…
Familiar words in the “Oil Patch”…
But where does oil and gas come from?
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For the most part, ALL of Earth’s energy is provided by our Sun.
Plants harness that energy and produce sugars and fats that are consumed as food by animals.
This food can be considered as ‘energy packets’ and when plants and animals die this energy gets ‘trapped’ as organic matter.
The organic matter that doesn’t get consumed gets buried in lakes, swamps and oceans along with sediments, grains of ‘dirt’ (mud, clay, silt and sand).
Over vast amounts of time this organic matter (trapped in layers of mud) gets buried deeper and deeper into the earth. It forms layers of rock which are known as “source rock” from which oil and gas are generated.
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The plants and ‘critters’ that make up the organic matter, the ‘storehouses of energy’, can not be seen with the ‘naked eye’. Microscopes allow us to see their incredible structure.
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Algae can reproduce in astounding numbers in lakes and seas giving rise to what is referred to as an ‘algal bloom’.
Green algae blooms in lakes is often referred to as “pond scum” and Red algae blooms in oceans is often referred to as “Red tides”.
In a single season some algal blooms can cover hundreds of square miles. Multiply that by hundreds and even thousands of years!
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Algal ‘blooms’ can be seen by satellite. This one (off the coast of SW England) covers an area in excess of hundreds of square kilometers! The inset white line is 80km in length.
This is a singular occurrence. Imagine the volume of algae in a hundred years, a thousand, a million or more!
That’s an incredible amount of organic matter which can eventually be converted into oil and gas.
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‘Fossil fuel’ is a “non-renewable” energy source with a finite supply.
Despite decades of ‘warnings’ and ‘cautions’ to reduce consumption mankind’s insatiable appetite for energy continues to grow.
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As “conventional oil” reserves diminish modern technology is being challenged to replace those reserves with “renewable energy”. One potential source is the growth of algae on an industrial scale to generate biodiesel.
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Another potential source of “unconventional” oil and gas reserves is the “Shale Plays”. What was once considered “source rock” with little to no permeability is now being drilled and fractured to produce gas and oil.
Fossil Fuel:Where does oil and gas come from?
Scale:What is big? What is small?
Plate Tectonics:What does it take to ‘move a mountain’?
Geological Time Scale:A thousand years is like a day.
Depositional Environments:How are rocks formed?
Well Correlations:Each new well is another piece of the puzzle.Well data is how we complete the puzzle.
Drilling and Completions:How do we find and produce oil and gas?
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Sediments (sand, silt and clay) form the rock layers that we frequently see in hillsides and mountains (outcrops).
The ‘Stacking Pattern’ and ‘layering’ of sediments can be seen in the next couple of slides in ‘small’ scale by way of the layers of beach sands and on a much ‘larger’ scale in whole mountains (especially evident in places like the Grand Canyon).
Geoscientists must always be aware of the scale of the data-sets that they are working with.
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Before we consider some of the ‘bigger’ concerns of geology, let us look at some of the ‘smaller’ things.
Most people are familiar with large fossils such as dinosaur bones but the vast majority of ‘fossil remains’ can only be seen with a microscope.
The following slides depict some of these differences in scale (size).
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In the absence of any type of scale these two shark’s teeth appear to be the same size.
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A penny provides a relevant scale. 30
There is a shark’s tooth on the penny. 31
There is a shark’s tooth on the penny. 32
These two pictures are of the same tooth. The one on the penny (left) has been ‘distorted’ due to ‘resizing’ from the previous photo.
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Next, we will look at rock samples.
Patterns that can be seen in rock samples on a ‘small’ scale are also present on a ‘large’ scale.
The following slides depict some of these differences in scale (size).
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Some ‘lines’ have been superimposed over the Terra Nova core sample to highlight the natural layering or ‘lineations’ that are present but a little less ‘obvious’ from the photo.
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It is difficult to see any ‘parallel layering’ or ‘lineations’ on a cylindrical core.
The obvious parallel layers of a ‘slabbed’ sandstone core (from the Hibernia Field) have been superimposed over the cylindrical core photo (which is the same size) to help further illustrate differences in scale in the following slides.
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Sands found on a beach show layering. That layering is also seen in the “core” sample from the Hibernia reservoir (taken from more than two miles below the seafloor). Those sands were originally formed in a beach environment much like this one. 40
That layering seen in the Hibernia “core” sample can also be seen on a much larger scale over vast distances in hills and mountains. Studies of “outcrops” help geologists determine where to look for oil and gas in the “subsurface” (below ground). 41
This should be a familiar scene. Note the ‘lineations’ in the “outcrop” of Signal Hill.(St. John’s, Newfoundland)
It is evident that the ‘layering’ of the “beds” is very steeply “dipping” and nearly vertical.
Of course, these beds would have originally been laid down in a near horizontal position.
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This should be a familiar scene. Note the ‘lineations’ in the “outcrop” of Signal Hill.(St. John’s, Newfoundland)
It is evident that the ‘layering’ of the “beds” is very steeply “dipping” and nearly vertical.
Of course, these beds would have originally been laid down in a near horizontal position.
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Fossil Fuel:Where does oil and gas come from?
Scale:What is big? What is small?
Plate Tectonics:What does it take to ‘move a mountain’?
Geological Time Scale:A thousand years is like a day.
Depositional Environments:How are rocks formed?
Well Correlations:Each new well is another piece of the puzzle.Well data is how we complete the puzzle.
Drilling and Completions:How do we find and produce oil and gas?
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Most people have heard of “global warming” and are aware that sea-level is rising around the globe.
In geologic time, sea-level is constantly rising and falling and will continue to do so for millions of years to come (more on this later).
Geologists have been able to determine how sea-level is able to change with time and how the ‘layers’ of rock or “beds” can get moved from horizontal to near vertical positions.
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As the detail of the mapping progressed the apparent ‘fit’ seemed more compelling.
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The ‘continental drift’ of Europe and Africa away from North and South America started about 220 million years ago.
The “Mid Atlantic Rift” is making new oceanic crust and forcing the Americas away from Europe and Africa. There is another “spreading center” in the Pacific.
The west coasts of North and South America are colliding with the Pacific Ocean plates. This ‘collision’ is causing the Rocky Mountains and the Andes to continue to rise, albeit by only millimeters per year.
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The ‘continental drift’ of Europe and Africa away from North and South America started about 220 million years ago.
The “Mid Atlantic Rift” is making new oceanic crust and forcing the Americas away from Europe and Africa. There is another “spreading center” in the Pacific.
The west coasts of North and South America are colliding with the Pacific Ocean plates. This ‘collision’ is causing the Rocky Mountains and the Andes to continue to rise, albeit by only millimeters per year.
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60Present Day: Satellite imagery shows the ‘true fit’. The continents have separated along a line that is known as the “Mid Atlantic Ridge”.
61Present Day: Satellite imagery shows the ‘true fit’. The continents have separated along a line that is known as the “Mid Atlantic Ridge”.
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The very visible E-W lineations are known as “transform faults”. The N-S lineations are part of the “Mid-Atlantic Ridge” or “spreading center”. The ocean floor that separates South America from Africa is ‘new’ relative to the continents themselves. Plate Tectonics helps to explain how this happened.
The very visible E-W lineations are known as “transform faults”. The N-S lineations are part of the “Mid-Atlantic Ridge” or “spreading center”. The ocean floor that separates South America from Africa is ‘new’ relative to the continents themselves. Plate Tectonics helps to explain how this happened. 63
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Close-up of the E-W lineations or “transform faults”. The N-S lineations form the mid-Atlantic ridge which is a “spreading center” where molten lava makes its way to the surface and forms new oceanic crust.
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Most people find it difficult to think in terms of millions and hundreds of millions of years but geoscientists have to think that way.
Very small movements (millimeters per year) over very long times result in mountains being raised out of the sea and worn down again to be deposited back into the sea. This is known as the “Rock Cycle”.
The following slides are called Plate Reconstructions.
Geologists are able to ‘reconstruct’ how the Earth would have looked with the help of seismic images and the data gathered from the hundreds of thousands of wells that have been drilled into the earth in the search for oil and gas.
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Triassic Period approximately 220 million years ago .
All of the world’s continents were joined into one giant continent called “Pangaea”. The light blue areas are ‘shallow seas’ where sediment is being deposited along shorelines and life is abundant. Many of these areas are locations of present day oil and gas reservoirs where hundreds and even thousands of wells have been drilled and which have helped us piece together these “plate reconstructions”
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Jurassic Period approximately 150 million years ago.
Seventy million years have passed since the previous ‘snapshot’. South America and Africa are still ‘attached’ but they are becoming separated from North America. The area within the red rectangle contains the Jeanne d’Arc basin. Huge volumes of coarse sand are being deposited in what will become the Terra Nova and Hebron Oilfields.
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Late Cretaceous approximately 90 million years ago.
Another 60 million years have passed since the last ‘snapshot’. The present day configuration of the continents is becoming more obvious. The pale blue areas represent shallow seas and are spread all over North America, Africa and Europe. In the Jeanne d’Arc basin reservoir sands of the Hibernia, White Rose, and numerous other fields are being deposited.
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Tertiary (Paleogene) approximately 50 million years ago.
The pattern of the present day continents is more obvious now. The west coast of North and South America is colliding with the Pacific plate which has closed the interior sea of Western Canada and the United States and begun to form the Rocky Mountains and the Andes. From the northern most tip of Alaska to the southern most tip of Argentina what was once shoreline and sea-floor sediments is being lifted up into a vast mountain chain.
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Tertiary (Recent) approximately 20 million years ago.
The pattern of the continents looks very familiar now, Most of the shallow ‘inter-continental’ seas have disappeared. Vast amounts of sediment are being deposited along the coastlines of the globe, pushing the previous sediments deeper into the earth. Millions of years of build up of organic matter is now being ‘cooked’ and turned into oil and gas. Pressure squeezes the hydrocarbons out of the “source rocks” into the reservoir rocks that overlie them.
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Still not convinced that this is possible?
That whole continents can move thousands of kilometers away from each other.
That beach sands could be ‘buried’ thousands of meters below the sea floor and then be lifted thousands of meters above sea-level (like Mt. Everest).
The ‘key’ that makes all this possible is the vast, vast, amount of time that has passed since the Earth was first formed… approximately 4.5 billion years ago.
That’s 4,500 million years ago.
Fossil Fuel:Where does oil and gas come from?
Scale:What is big? What is small?
Plate Tectonics:What does it take to ‘move a mountain’?
Geological Time Scale:A thousand years is like a day.
Depositional Environments:How are rocks formed?
Well Correlations:Each new well is another piece of the puzzle.Well data is how we complete the puzzle.
Drilling and Completions:How do we find and produce oil and gas?
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We will soon take a look at the Geological Time Scale.
For now, let us consider the thickness of a single piece of paper… (approximately one tenth of one millimeter).
Then think of a ‘package’ of paper that contains 500 sheets of paper… (50 millimeters or 5 centimeters).
A stack of twenty packages of paper contains 10,000 sheets of paper… (1000 millimeters, or 1 meter).
A six foot tall person is approximately 2 meters tall,20,000 sheets of paper.
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Rates of Deposition (burial) or Erosion ( or ‘uplift’).
You could bury the world’s tallest buildings (or erode them) in as little as 4 to 5 million years (at a rate of one sheet per year).
Every ten million years you could deposit or erode a full kilometer of sediment.
Ten million years seems like a vast amount of time (and it is).
Yet the youngest oil-producing formation in the Hibernia oilfield (Ben Nevis)…is approximately 100 million years old.
The Ben Nevis is ‘buried’ to an average depth of about three kilometers.It could have been buried to a depth of 10 kilometers in that time (at one sheet per year).The oil-producing horizons in the Terra Nova field are approximately 150 million years old!
So you see, even at what seems like an infinitesimally small rate of either ‘erosion, burial or uplift’ there is more than enough time available to build a mountain and tear it down again!
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These mountains resulted from the ‘collision’ of the Indian Plate a mere 50 million years ago. So these mountains were “uplifted” at a rate or approximately TWO sheets per year! 84
The formations that produce oil and gas in the Jeanne d’Arc Basin were once deposited at or near sea-level and have since been buried deeply into the earth.
We can determine the ages or “Geological Time Periods” that those rocks were deposited in from a number of different methods.
Radiometric dating and presence and type of fossils are the most common methods,
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This portion is enlarged on the next slide.
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In geological time sea-level is constantly changing (rising and falling).
There have been periods of extremely ‘high’ sea-level when vast areas of the continents were covered by oceans and ‘inland seas’.
One can look at the records of sea-level rise and fall in relatively ‘recent’ terms (the past 100+ years).
In terms of the last “Ice Age” (~15,000 years ago).
Or records throughout “Geological Time”(4.5 billion years total, with 500+ million years of life).
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Records for the past 100+ years show that sea-level has risen by 20cm (200mm) or approximately 2mm per year.
Using our previous ‘stacked paper’ analogy, that is 2,000 sheets of paper or approximately 16 sheets per year.
However, sea-level has been rising ‘rapidly’ since the last ‘glacial melt’ approximately 15,000 years ago.
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15,000 years ago during the last “Ice Age” sea-level was 100 meters lower than it is today because a lot of the Earth’s water was frozen as ice in glaciers.
Since that time sea-level has risen by 100m.(66 sheets per year).
In “Geological Time” since there has been ‘abundant’ life in the oceans (500+ million years ago) sea-level has frequently been hundreds of meters higher than present day. Sea-level has also been very much lower than present day.
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The continents have moved due to Plate Tectonics.
Mountains have been raised and then leveled by weathering and erosion.
The rock fragments from erosion of the mountains make their way to the sea and get deposited once again.
Sea-level constantly rising and falling results in beaches being ‘swallowed’ by the sea.
These are on-going processes of the “Rock Cycle”.
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Fossil Fuel:Where does oil and gas come from?
Scale:What is big? What is small?
Plate Tectonics:What does it take to ‘move a mountain’?
Geological Time Scale:A thousand years is like a day.
Depositional Environments:How are rocks formed?
Well Correlations:Each new well is another piece of the puzzle.Well data is how we complete the puzzle.
Drilling and Completions:How do we find and produce oil and gas?
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Mountains get eroded, forming sediment (gravel, sand, silt and mud). Rivers move that sediment into lakes and oceans. Waves and tides continue to move that sediment around. Incredible volumes of organic matter ‘rain down’ to the sea floor and get deposited together with the sand, silt and mud. Sediments and organic matter get buried deeper and deeper over time, eventually forming source rocks and reservoirs.
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106Micro-Environments of a Clastic Shoreline
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Stacking Patterns
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Oil and Gas reservoirs occur in sediments that were deposited and buried in ‘ancient’ depositional environments.
The following slides show these environments in ‘modern’ settings.
The current Hibernia, Terra Nova, White Rose and Hebron Fields that are buried thousands of meters below the sea-floor were once much like these environments… at or near sea-level.
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Mountainous ‘highlands’ with alluvial fans at the base and terraced sediments deposited by rivers and streams.
Rivers redistribute the sediment and carve river valleys that form terraces (‘steps’) from ‘earlier’ incised valleys.
The eroded rock and sediment spills out onto floodplains. In addition to coarse grained sediments there are fine grained sediment (clays and muds) that support vegetation. This type of environment is ideal for farmland.
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Braided fluvial channels in an incised valley. Note the ‘rocky outcrop’ along the valley edges.
There is very little vegetation within the river valley which is typically evidence of high rates of water flow and relatively steep gradients. The fertile farmland in the background contains muds and clays from times when the river overflows its banks unto the ‘floodplain’.
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Where rivers meet the sea you frequently find barrier Islands with sandy beaches, tidal inlets and muddy lagoons.
These environments are great places to live for a time but they are constantly changing due to waves and tides and as sea level rises and falls through time.
Shoreline erosion and migration is constant despite man’s ceaseless efforts to prevent such change.
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Where fluvial (river) systems merge with open ocean (marine) systems and sedimentation rates are high deltas may form.
This delta has multiple distributary channels that ‘fan out’ and distribute the sediment into the nearshore environment. These deposits are constantly modified by waves and tides.
‘Modern’ deltas have played a very important role in the history of humans on this planet. ‘Ancient’ deltas are frequently targeted for their oil and gas reserves.
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The Nile delta (shown here) clearly shows the importance of fresh water river systems for agriculture.
Arid conditions exist everywhere within only a very short distance from the ‘life sustaining’ waters of the Nile.
This is a ‘modern’ delta.
‘Ancient’ deltas are frequently targeted for their excellent oil and gas reservoir qualities.
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Sand, silt and clay is not only transported and deposited by water.
The wind can, and does, also play a role…
In arid, dry, desert environments, the wind is constantly reshaping the landscape. Sand, silt and clay are moved about in enormous volumes in ‘storms’ that are very common in these types of environments. 130
The sheer scale of these ‘sandstorms’ is almost incomprehensible to those of us who have not personally experienced them. 131
Sands, silts and clays that are blown about in storms such as this are lifted high into the atmosphere and are blown all the way from Africa to South America and even all the way to North America. 132
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Satellite imaging showing ‘dust’ being blown from Africa, heading west across the Atlantic ocean to South America and beyond.
Africa
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From ‘modern’ depositional environments to ‘ancient’ depositional environments.
The following slides illustrate the types of depositional environments that contribute to the reservoirs found in the Jeanne d’Arc Basin (East Coast Canada).
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We have seen how mountains are ‘uplifted’ from the sea and then eroded and deposited back into the sea.
The sand, silt and clay, the “weathering products” are moved from the ‘highlands’ to the ocean in a continuous process called the “Rock Cycle”.
These ‘rock fragments’ form the “source rocks” that oil and gas is formed in and they form the “reservoir rocks” that oil and gas is produced from.
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The amount of porosity and permeability in reservoir rocks is often a function of the ‘parent rocks’ that the grains are eroded from.
The distance that those grains travel before they are deposited will also affect the grain size and shape and degree of sorting; all are factors which affect the porosity and permeability.
Additionally, sand grains that are deposited in a beach environment will likely be reworked over and over by wave action and tides. This results in angular grains becoming rounded, clays are removed and the sorting is increased.
Geologists need to study the source of the sediment and the environments of deposition in order help them predict where the best reservoirs can be found.
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Oil comes out of the ground from microscopic holes in the rock called “pores” or “pore spaces”. The measure of the amount of pore space relative to the amount of solid rock is called porosity and it is expressed as a percentage. Some estimate of the porosity is essential to determine how much oil there could be in a potential reservoir (the size of the resource).
The next essential component of a reservoir is how well connected those pore spaces are and how well oil or gas can flow through the rock. This is called permeability and is typically measured in units of millidarceys. The higher the permeability of the rock the better the flow rate and the more oil or gas you can produce (the larger the reserves).
Key Reservoir Rock Properties
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In a later section we will be shown more detail on HOW a well is drilled.
At the moment it is sufficient to say that a drilling rig uses a “drill bit” to drill down into the solid rock layers.
The drill bit breaks up the rock layers into small pieces called “cuttings”. The geologist, or ‘mudlogging geologist’ at the “well-site” examines these cuttings under a microscope to determine what is the rock type (sandstone, shale, limestone) and whether or not there is any porosity and permeability.
The geologist also looks at these cuttings for their size (fine or coarse) and shape (angular or round) and other parameters that help to determine the “environment of deposition” of the sediments that make up the ‘rock layers’.
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The geologist attempts to determine the ‘properties’ of the cuttings, their size and shape and degree of sorting.
These properties affect the reservoir porosity and permeability and ultimately, how much oil and gas you can produce from the reservoir.
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Fossil Fuel:Where does oil and gas come from?
Scale:What is big? What is small?
Plate Tectonics:What does it take to ‘move a mountain’?
Geological Time Scale:A thousand years is like a day.
Depositional Environments:How are rocks formed?
Well Correlations:Each new well is another piece of the puzzle.Well data is how we complete the puzzle.
Drilling and Completions:How do we find and produce oil and gas?
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Wireline Logging Types.
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The Porosity log indicates reservoir.
Non-reservoir quality
Reservoir quality
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Wireline log measurements reveal a great deal of information about the rock types and potential oil and gas reservoirs.
Core samples are frequently taken in the ‘reservoir section’ of a well. Many additional measurements are then obtained and are compared to their ‘wireline signature’.
These comparisons can reveal a great deal of information from other wells that do not have any core samples.
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Note similarity with the E Sand in L-98 9
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Here are four wells showing the GR and Res logs.See any patterns? Geologists “correlate” wells by ‘connecting’ layers that look similar.
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Start the “correlation” by adding some straight lines to connect the ‘wireline signatures’ (remember the ‘layering’ from previous slides).
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Also remember that not all ‘beds’ are horizontal. Some have been tilted, faulted and even folded.
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Also remember that not all ‘beds’ are horizontal. Some have been tilted, faulted and even folded.
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And some more lines… (correlations).
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And a few more ‘lines’…This shows ‘flat lying’ beds on top of ‘tilted’ (and eroded) beds.
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You can even add a little color to complete the ‘picture’.Accurate “correlations” help to determine the ‘best’ places to drill and find more oil and gas deposits.
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One last example… Do you see any patterns?
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If we start “correlating” with straight lines we will see this pattern evolve…
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A geologist might recognize that ‘curved lines’ would be a better ‘fit’ in this “correlation”.
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This interpretation is of “folded” beds, like the picture in the next slide.
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Folded beds are a result of Plate Tectonic “compressional forces”.
Fossil Fuel:Where does oil and gas come from?
Scale:What is big? What is small?
Plate Tectonics:What does it take to ‘move a mountain’?
Geological Time Scale:A thousand years is like a day.
Depositional Environments:How are rocks formed?
Well Correlations:Each new well is another piece of the puzzle.Well data is how we complete the puzzle.
Drilling and Completions:How do we find and produce oil and gas?
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How do we determine where to drill for oil?
Data is acquired at every stage of the search for oil and gas. In the exploration phase seismic is the primary data set. Seismic surveys are carried out over vast areas (tens and even hundreds of square kilometers) on land and at sea.
Seismic provides a basin-wide view of the rocks and structures beneath the land surface or ocean floor. The data is necessary to reduce uncertainty and risk and to help identify locations to drill wells. Without seismic it would be akin to drilling ‘blind’.
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Early in the “Exploration Phase” seismic acquisition is used to ‘image’ the rocks below the land surface (or below the sea-floor for offshore areas).
The vast majority of the world’s oil and gas reservoirs are found in ‘layers’ of sedimentary rocks that reflect (and refract) sound waves. The seismic images are processed and drilling ‘targets’ (or prospects) are identified.
184A typical resultant 2D image is shown in the seismic line above.
185Note: The deeper layers are not continuous; they are ‘broken’ or faulted. Faulting makes it much more difficult to map and produce the oil and gas reservoirs.
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Multiple 2D seismic lines are processed so that a 3D image can be generated.
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3D image of the Hibernia Field. Two wells are displayed. The one on the left is an ‘up dip’ oil producer and the one on the right is a ‘down dip’ water injector. These are referred to as a “producer and injector pair”.
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3D image of the Hibernia Field with numerous wells displayed. Each new well enhances the understanding of the field and helps determine where the next well will be placed to maximize the oil recovery from the Field.
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It is not simply a matter of ‘digging’ a hole in the ground to produce oil and gas. It is a very complicated process that requires a great deal of technology.
Wells are drilled in stages, one section at a time, followed by what is called a “casing run” to ‘line’ the hole to prevent it from ‘caving in’ (and for other reasons).
The first stage drills the well to a relatively ‘shallow’ depth and then emplaces the first “casing string”; this is called the Conductor Casing.
This is followed by drilling to a ‘deeper’ depth and another “casing run” and so on until the well is drilled to the Final Total Depth (FTD).
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Wells are not only drilled to produce the oil in the reservoir.
Wells are drilled to inject other fluids into the reservoir to maintain pressure and increase the amount of oil that can be produced.
Water and gas are the most common fluid types used
in injection wells.
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There are four components which must be present for oil and gas to accumulate in commercial quantities.
Source: Organic material (plants and animals) that gets ‘cooked’ as the temperatures and pressures increase with burial.
Reservoir: Pore space that can store or hold the hydrocarbons.
Seal: Typically very fine grained, clayey material (shale) that is impermeable (fluids cannot move or ‘flow’ through it).
Trap: Typically a structural feature such as a fold or a fault that isolates and encloses an oil or gas reservoir.
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Hydrocarbons do not dissolve in water; they are less dense than water and (due to buoyancy) will try to rise to the surface.
Oil and gas will rise through the rock column until it reaches an impermeable layer that it cannot pass through (a seal). The hydrocarbons will then accumulate in the porous rock layers below the seal (the reservoir).
IF there is both oil and gas present in a reservoir the gas is less dense and will ‘float’ on the oil. Oil is less dense than water and will ‘float’ on the water.
The result is that there will be distinct ‘layers’ in the reservoir, a “gas cap”, an “oil leg” and a “water leg”.
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Hydrocarbons do not dissolve in water; they are less dense than water and (due to buoyancy) will try to rise to the surface.
Oil and gas will rise through the rock column until it reaches an impermeable layer that it cannot pass through (a seal). The hydrocarbons will then accumulate in the porous rock layers below the seal (the reservoir).
IF there is both oil and gas present in a reservoir the gas is less dense and will ‘float’ on the oil. Oil is less dense than water and will ‘float’ on the water.
The result is that there will be distinct ‘layers’ in the reservoir, a “gas cap”, an “oil leg” and a “water leg”.
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Multiple wells are drilled into an oilfield in order to maintain the pressure and maximize the amount of hydrocarbons that can be produced.
Well A penetrates the ‘water leg’; it does not intersect the gas or oil leg.
Well B penetrates the ‘water leg’ and the ‘oil leg’.
Well C penetrates the ‘reservoir in the gas, oil and water legs.
In this scenario, Well B would be the oil producer and Wells A and C would be “injection wells”. Well A would inject water in the ‘water leg’ and Well C would inject gas into the ‘gas cap’.
A CB
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Multiple wells are drilled into an oilfield in order to maintain the pressure and maximize the amount of hydrocarbons that can be produced.
Well A penetrates the ‘water leg’; it does not intersect the gas or oil leg.
Well B penetrates the ‘water leg’ and the ‘oil leg’.
Well C penetrates the ‘reservoir in the gas, oil and water legs.
In this scenario, Well B would be the oil producer and Wells A and C would be “injection wells”. Well A would inject water in the ‘water leg’ and Well C would inject gas into the ‘gas cap’.
A CB
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As the oil is produced it needs to be stored and then transported to market.
In the offshore environment there are many types of vessels involved with the production, storage and transportation of oil and gas to markets.
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The Hibernia Platform is a Gravity Based Structure (GBS) that is attached to the seafloor. The produced oil is stored in the ‘legs’ till it is offloaded to tankers.
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Terra Nova and White Rose oil production is from large specialized ‘ships’ called FPSO’s (Floating, Production, Storage and Offloading).
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Oil is produced from the Husky White Rose Field from the FPSO (Floating Production Storage and Offloading) vessel the “Sea Rose”. There is a similar vessel used in production from the Terra Nova Field.
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In an offshore environment gas is much more difficult to transport than oil. It is typically shipped via pipeline to a facility on land and may then be pressurized and liquefied so that it can be transported by sea to markets that are frequently very remote from where the gas is being produced. This is a Liquefied Natural Gas tanker (LNG). There is not yet any gas production from the Newfoundland and Labrador offshore.
