cause of depletion of natural resources
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Oil depletion occurs in the second half of the production curve of an oil well, oil field, or the average of total world oil production. The Hubbert peak theory makes predictions of production rates based on prior discovery rates and anticipated production rates. Hubbert curves predict that the production curves of non-renewing resources approximate a bell curve. Thus, when the peak of production is passed, production rates enter an exponential decline.
The American Petroleum Institute estimated in 1999 the world's oil supply would be depleted between 2062 and 2094, assuming total world oil reserves at between 1.4 and 2 trillion barrels and consumption at 80 million barrels per day. In 2004, total world reserves were estimated to be 1.25 trillion barrels and daily consumption was about 85 million barrels, shifting the estimated oil depletion year to 2057. A study published in the journal Energy Policy by researchers from Oxford University, however, predicted demand would surpass supply by 2015 (unless constrained by strong recession pressures caused by reduced supply or government intervention).
The United States Energy Information Administration predicted in 2006 that world consumption of oil will increase to 98.3 million barrels per day (mbd) in 2015 and 118 mbd in 2030. With 2009 world oil consumption at 84.4 mbd, reaching the projected 2015 level of consumption would represent an average annual increase between 2009 and 2015 of 2.7% per year while EIA's own figures show declining consumption and declining supplies during the 2005-2009 period.
The world's oil supply is fixed because petroleum is naturally formed far too slowly to be replaced at the rate at which it is being extracted. Over many millions of years, plankton, bacteria, and other plant and animal matter become buried in sediments on the ocean floor. When conditions are right â€“ a lack of oxygen for decomposition, and sufficient depth and temperature of burial â€“ these organic remains are converted into petroleum compounds, while the sediment accompanying them is converted into sandstone, siltstone, and other porous sedimentary rock. When capped by impermeable rocks such as shale, salt, or igneous intrusions, they form the petroleum reservoirs which are exploited today.
Production decline models
Oil production decline occurs in a predictable manner based on geological circumstances, governmental policies, and engineering practices. The shape of the decline curve varies depending upon whether one considers a well, a field, a set of fields, or the world.
Oil well production decline
Oil well production curves typically end in an exponential decline. At natural rates, oil well production curves appear similar to a bell curve, a phenomenon known as the Hubbert curve. The typical decline is a rapid drop in production, and eventually a leveling off to a point at which they no longer produce profitable amounts. Such wells are referred to as marginal or stripper wells.
The shape of production curve of an oil well can be affected by a number of factors:
- * Well may be restricted by choice by lack of market demand or government regulation. This flattens the peak of the curve, but will not change the well's total production significantly.
- * Hydraulic fracturing (fracing) or acidizing may be used to cause a sharp spike in production, and may increase the recoverable reserves of a given well.
- * The field may undergo a secondary or tertiary recovery project, discussed in the next section.
Oil field production decline
Each individual oil well is a portion of a larger fixed area oil field. As with individual wells, discovery and production amounts of oil fields generally average to a similar bell shaped production curve. Eventually, when the field is completely drilled out, a field's production goes into a sharp decline as the average production of its wells enter decline. As this decline levels off, production can continue at relatively low rates. A number of oil fields in the U.S. have been producing for over 100 years.
Oil field production curves can be modified by a number of factors:
- * Production may be restricted by market conditions or government regulation.
- * A secondary recovery project, such as water or gas injection, can repressurize the field and improve the production rate temporarily. However, it will not change the total production amount over the life of the field. Eventually the field will go into a steeper than normal decline.
- * the field may undergo an enhanced oil recovery project, such as drilling of wells for injection of solvents, carbon dioxide, or steam. This can be very expensive but allows more oil to be coaxed out of the rock, increasing the ultimate production of the field.
Multi-field production decline
Most oil is found in a small number of very large oil fields. If oil fields are discovered at a constant rate until they have all been found, the combined production of fields will yield a curve such as the one at right. Production starts off slowly, rises faster and faster, then slows down and flattens until it reaches a peak. After the production peak, production enters an exponential decline, eventually flattening out. Oil production may never actually reach zero, but eventually becomes very low. Factors which can modify this curve include:
- * Inadequate demand for oil, which reduces steepness of the curve and pushes its peak into the future. <
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Answers:1 -Sun and its energy 2 -Natural is natural only one type. Yes there are number of them 3 -Over use of it like Ground water it has been so much use that in some places the land has gone barren. 4 -Use it in limit the saying is 'Excess of every thing is bad'
Answers:They are linked but not in direct ways. The major problem facing humanity is population growth and the size of our present global population. The greater the number of people, the greater the use of resources (simple night follows day scenario) Up to the present, and for some time to come, we have used carbon based fuels, which on combustion produce carbon dioxide and water (plus other odds and sods). So - increased population results in increased carbon dioxide output. It is argued that the carbon dioxide levels have now increased to the point where there is a measurable effect on global temperatures (greenhouse effect). With ozone depletion, the problem is principally caused by the release of fluoro-chloro hydrocarbons into the atmosphere (now being controlled). So the more of us there are around, the more of these CFCs were released. Acid rain comes in two sorts - natural and 'artificial'. The natural sort has always been there and is caused by carbon dioxide dissolving in rain to form the weak, unstable Carbonic Acid. The 'artificial' sort comes from the release of sulphur dioxide caused by the burning of sulphur containing fuels; this dissolves in rain to form, eventually, sulphuric acid; this is a strong acid. Again we have started to control this and the output of sulphur dioxide was related to demand and thus population. This is a bit succinct, but should give you the main threads.
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Answers:Question 1! It takes more land and concentrated farming and a good retirement income to be a farmer or rancher in the 21st century. In 1941 people could exist on their farming abilities. The world didn't expect us to pay $50,000 for a simple vehicle and half a mil for a tractor. A combine costs in the neighborhood of one mil to one and a half, USD!! in the 21st century. In 1941 some were still using animals to pull the plows and harvesting machinery, Last question!! BSE in that one cow caused the export door to slam shut. Cows couldn't even be moved from one province to another. If a rancher/farmer cannot sell his "product" he cannot continue. Most of the farm/ranches had to eat all their excess calves themselves because they couldn't sell them. Their markets depended heavily on the USA export. With that door and the Asian markets closed down, there was no where to go with the animals. With no income, most of the industry went into bankruptcy courts. Animals that can't be fed are killed and buried on the spot in huge land fills.