Exploration & Production Geology
Posted by admin in Uncategorized on June 11th, 2010
Petroleum geology is a term used to refer to the specific set of geological disciplines that are applied to the search for hydrocarbons. It is principally concerned with the evaluation of seven key elements in sedimentary basins: Source, Reservoir, Trap, Seal, Timing, Maturation, Migration
In general, all these elements must be assessed via a limited ‘window’ into the subsurface world, provided by one (or possibly more) exploration wells. These wells present only a 1-dimensional segment through the Earth and the skill of inferring 3-dimensional characteristics from them is one of the most fundamental in Exploration and Production geology. Recently, the availability of cheap and high quality 3D seismic data has greatly aided the accuracy of such interpretation.
Evaluation of the source uses the methods of geochemistry to quantify the nature of organic-rich rocks which contain the precursors to hydrocarbons, such that the type and quality of expelled hydrocarbon can be assessed.
The reservoir is a porous and permeable lithological unit or set of units that holds the hydrocarbon reserves. Analysis of reservoirs at the simplest level requires an assessment of their porosity (to calculate the volume of in situ hydrocarbons) and their permeability (to calculate how easily hydrocarbons will flow out of them). Some of the key disciplines used in reservoir analysis are the fields of stratigraphy, sedimentology, and reservoir engineering.
The seal, or cap rock, is a unit with low permeability that impedes the escape of hydrocarbons from the reservoir rock. Common seals include evaporites, chalks and shales. Analysis of seals involves assessment of their thickness and extent, such that their effectiveness can be quantified.
The trap is the stratigraphic or structural feature that ensures the juxtaposition of reservoir and seal such that hydrocarbons remain trapped in the subsurface, rather than escaping (due to their natural buoyancy) and being lost.
Analysis of maturation involves assessing the thermal history of the source rock in order to make predictions of the amount and timing of hydrocarbon generation and expulsion.
Finally, careful studies of migration reveal information on how hydrocarbons move from source to reservoir and help quantify the source (or kitchen) of hydrocarbons in a particular area.
If the likelihood of there being a source rock is thought to be high, then next matter to address is the state of thermal maturity of the source, and the timing of maturation. Maturation of source rocks (see diagenesis and fossil fuels) depends strongly on temperature, such that the majority of oil generation occurs in the 60° to 120°C range. Gas generation starts at similar temperatures, but may continue up beyond this range, perhaps as high as 200°C. In order to determine the likelihood of oil/gas generation, therefore, the thermal history of the source rock must be calculated. This is performed with a combination of geochemical analysis of the source rock (to determine the type of kerogens present and their maturation characteristics) and basin modelling methods, such as backstripping, to model the thermal gradient in the sedimentary column.
Several major subdisciplines exist in petroleum geology specifically to study the seven key elements discussed above.
Analysis of reservoir
Once a possible hydrocarbon reservoir is identified, the key physical characteristics of a reservoir that are of interest to a hydrocarbon explorationist are its porosity and permeability. The existence of a reservoir rock (typically, sandstones and fractured limestones) is determined through a combination of regional studies (i.e. analysis of other wells in the area), stratigraphy and sedimentology (to quantify the pattern and extent of sedimentation) and seismic interpretation. Traditionally, these were determined through the study of hand specimens, contiguous parts of the reservoir that outcrop at the surface and by the technique of formation evaluation using wireline tools passed down the well itself. Modern advances in seismic data acquisition and processing have meant that seismic attributes of subsurface rocks are readily available and can be used to infer physical/sedimentary properties of the rocks themselves.
Analysis of source rocks
In terms of source rock analysis, several facts need to be established. Firstly, the question of whether there actually is any source rock in the area must be answered. Delineation and identification of potential source rocks depends on studies of the local stratigraphy, palaeogeography and sedimentology to determine the likelihood of organic-rich sediments having been deposited in the past.
What is Deep Linking?
Deep linking is the creation of a hyperlink that directly links to specific content on another website, instead of linking to a site’s main or “front” page. Some argue that deep linking is good because it benefits everyone: it makes the linking Web pages more useful and usable and increases the popularity of pages other than your homepage.
Some commercial sites object to others making deep links into their content, either because it bypasses advertising on their main pages or, like The Wall Street Journal, they charge users for permanently-valid links. Many critics charge that such sites simply want to establish policies that will “license” such links to the highest bidder. They argue that links are a fundamental part of “user-oriented” web browsing.
There is no technical distinction between a so-called “deep” link and any other link.
What is a Divorce?
Posted by admin in Social Sciences on January 23rd, 2009
Divorce is the ending of a marriage, which can be contrasted with an annulment, a declaration that a marriage is void, though the effects of marriage may be recognized in such unions, such as spousal support, child custody and distribution of property. Divorce is rarely good news and it takes a lot of pragmatism and good will to accomplish a “good” divorce. Although divorce is an extremely traumatic experience for any parent to go through, the first steps are always the most important and the main priority is to keep a level head. Divorce means everything you once took for granted as a child is going to change. The bad thing about divorce is that you no longer share the same friends (in most situations).
In developed countries, divorce rate have increased markedly during the twentieth century. Among the states in which divorce has become commonplace are the United States, Japan, Korea and European Union countries. In Anglo-American jurisdictions this boom in divorce developed in the last half of the twentieth century, corresponding, more or less, with the abolution of such concepts as illegitimacy and the development of the equality of the sexes. The area of divoce as a social phenomenon is is an important research topic in sociology.
Some researchers, although, argue that divorce rate does not always reflect actual interaction among people; that is, some countries may show a low divorce rate because in such countries, people rarely get married in the first place. Heavily depending on cultural values and tax system with marriage, people start marriage and end it. In countries such as France, people who have romatic relationships or children tend to avoid marriage, thus, divorce rate has remained low.
In quite a few countries, divorce might involve economical difficulties. Because women can get a job with lower wages than men in almost all countries, wives tend to avoid divorce, being afraid of economical trouble. Single mothers are often produced after divoce and often they suffer from financial problems. Many national and local governments provide some kind of welfare system for them. See single mother for detail.
Divorce in some jurisdictions is relatively recent phenomenon. In Canada there was no divorce law until the 1960s. Before that the only way to get divorced was to apply to the Canadian Senate where a special committee would undertake an investigation of a request for a divorce and if they founded it was merited the marriage would be dissolved by an Act of Parliament.
Many countries in Europe, such as France prohibited divorce as it was not condoned by the Catholic church. Sometimes citizens would travel to other jurisdictions to obtain a divorce.
What is Periodontitis?
Periodontitis, or Pyorrhea, is a disease involving inflammation of the gums, often persisting unnoticed for years or decades in a patient, that results in loss of bone around teeth. This differs from gingivitis, where there is inflammation of the gingiva but without bone loss; it is the loss of bone around the teeth that differentiates between these two oral inflammatory diseases.
In most cases this disease is linked to poor oral hygiene. In particular, patients must regularly clean underneath their gumline in order to help disrupt the build-up of plaque and inflammation-generating toxins below the gumline. Some people, however, can have a genetic pre-disposition to the disease. Once initiated, the disease can progress more rapidly in people who have diabetes, especially if the diabetes is poorly controlled. Smoking is a strong risk factor for periodontal disease as it contains chemicals that can exacerbate existing inflammation, enhance bacterial growth, and prevent the synthesis of collagen, an important factor in healing damaged gingival tissue.
Symptoms may include the following:
- occasional redness or bleeding of gums while brushing teeth, using dental floss or biting into hard food (e.g. apples)
- occasional gum swellings that recur
- halitosis or bad breath
- persistent bad taste in the mouth
- recession of gums resulting in apparent lengthening of teeth. This may also be caused by heavy handed brushing using a hard tooth brush.
- pockets between the teeth and the gums (Pockets are sites where the jaw bone has been destroyed gradually or by repeated swellings)).
- loose shaky teeth in later stages
Patients should realize that the gingival inflammation and bone destruction are largely painless. Hence people may wrongly assume that painless bleeding after teeth cleaning is unimportant, although this may be a symptom of periodontitis progressing in that patient.
Measures to prevent periodontal disease include:
- brushing properly on a regular basis (2 times a day), with the patient attempting to direct the toothbrush bristles underneath the gum-line, so as to help disrupt the bacterial and plaque growth that may occur there.
- flossing daily and using interdental brushes if there is sufficient space between teeth and behind the last tooth in each quarter.
- using an antiseptic mouthwash. Listerine and its generic formulations, as well as Hydrogen Peroxide, may help prevent gingivitis, although they cannot reverse any bone loss due to periodontitis.
- regular dental check-ups and professional teeth cleaning as required. Dental check-ups serve to monitor the person’s oral hygiene methods and levels of bone around teeth, identify any early signs of periodontitis, and monitor if it has responded to treatment.
Dentists use special instruments to clean teeth below the gumline and disrupt any plaque growing below the gumline. This is a standard treatment to to prevent any further progress of established periodontitis. Studies show that after such a professional cleaning, bacteria and plaque tend to grow back to pre-cleaning levels after about 3-4 months. Hence, in theory, cleanings every 3-4 months might be expected to also prevent the initial onset of periodontitis. However analysis of published research has reported little evidence either to support this or the intervals at which this should occur. Instead it is advocated that the interval between dental check-ups should be determined specifically for each patient between every 3 to 24 months.
Nonetheless, the continued stabilization of a patient’s periodontal state depends largely, if not primarily, on the patient’s home care. Without good technique and habits at home, periodontal disease will not be overcome, especially if the patient has a history of extensive periodontal disease.
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What is Time Preference?
Time preference is the economist’s assumption that a consumer will place a premium on enjoyment nearer in time over more remote enjoyment. A high time preference means a person wants to spend their money now and not save it, whereas a low time preference means a person might want to save their money as well.
The time preference theory of interest is an attempt to explain interest through the demand for accelerated satisfaction. This is particularly important in microeconomics. The Austrian School sees time as the root of uncertainty within economics.
In his book Capital and Interest, the Austrian economist Eugen von Böhm-Bawerk built upon the time-preference ideas of Carl Menger, insisting that there is always a difference in value between present goods and future goods of equal quality, quantity, and form. Furthermore, the value of future goods diminishes as the length of time necessary for their completion increases.
Böhm-Bawerk cited three reasons for this difference in value. First of all, in a growing economy, the supply of goods will always be larger in the future than it is in the present. Secondly, people have a tendency to underestimate their future needs due to carelessness and shortsightedness. Finally entrepreneurs would rather initiate production with goods presently available, instead of waiting for future goods and delaying production.
Hans-Hermann Hoppe elaborates on time-preference as a gauge of the degree of civilization of a given society in his book Democracy: The God That Failed. Laws in a society in violation of property rights increase time-preference, whereas a tradition of respect for property rights decreases time-preference.
What are Economics?
Posted by admin in Social Sciences on January 16th, 2009
Economics is a social science that studies society’s allocation of scarce resources to meet desires and wants. Economics therefore starts from the premise that resources are in limited supply and that it is necessary to choose between competing alternatives.
Economics is “positive” when it attempts to explain the consequences of different choices and “normative” when it prescribes a certain route of action. Aspects receiving particular attention in economics are trade, resource allocation and competition.
Unlike most social sciences, economics can involve advanced mathematics, although the basics of economics can be taught with no more than simple arithmetic and graphs. Mathematical economics has developed as a field in itself.
What is Business?
The term business refers to activities or interests.
By extension the word became (as recently as the 18th century) synonymous with “an individual commercial enterprise” and has also sometimes taken on the meaning of “the nexus of commercial activities” or of “the representatives of commercial activity”.
Specifically, business can refer, collectively, to individual economic entities. In some legal jurisdictions, such entities are regulated by law to conduct operations on behalf of entrepreneurs. A manufacturing business is commonly referred to as an industry: for example: the “entertainment industry”, or the “dairy industry”, or the “fishing industry”.
What is a Store of Value?
To act as a store of value, a commodity, a form of money, or financial capital must be able to be reliably saved, stored, and retrieved - and be predictably useful when it is so retrieved.
This is distinct from the standard of deferred payment function which requires acceptability to parties one owes a debt to, or the unit of account function which requires fungibility so accounts in any amount can be readily settled. It is also distinct from the medium of exchange function which requires durability when used in trade, and a minimum of opportunity to cheat others.
When currency is stable, money can serve all four functions. When it isn’t, such as during times of hyperinflation or when complex and volatile forms of financial capital are involved, it becomes important to identify alternative stores of value, of which common ones are:
- real estate - actual deeds in protectible land
- gold - once the basis of the gold standard
- silver - once the basis of the silver standard
- precious stones, and other precious metals
- more stable currencies, e.g. Swiss franc or digital gold currency
- collectibles, e.g. original art by a famous artist or antiques
- livestock (see African currency)
While these items may be inconvenient to trade daily or store, and may vary in value quite significantly, they rarely or never lose all value. This is the point of any store of value, to impose a natural risk management simply due to inherent stable demand for the underlying asset. It need not be a capital asset at all, merely have economic value that is not known to disappear even in the worst situation. In principle, this could be true of any industrial commodity, but gold and precious metals are generally favored because of their demand and rarity in nature, which reduces the risk of devaluation associated with increased production and supply.
What is Credit Money?
Credit money is any future claim against a physical or legal person that can be used for the purchase of goods and services . Examples of credit money include personal I.O.U.’s, and in general any financial instrument (such as a treasury bond, savings bond, corporate bond or bank money market account certificate) which is not immediately repayable (redeemable) on demand. In certain cases, banknotes which are not legal tender may be seen as credit money, inasmuch as they are simply promisory notes issued by the bank (for example, see Pound Scots).
In terms of the money supply, credit money is generally associated with that part of M2 which is not M0.
During the Crusades in Europe, precious goods would be entrusted to the Roman Catholic Church’s Knights Templar, who effectively created a system of modern credit accounts. Over time this system grew into the credit money that we know today, where banks create money by approving loans - although the risk and reserve policies of each national central bank set a limit on this.
Sometimes, as in the United States during the Great Depression, trust in bank policies drops very low, and there is the risk of a bank run without government or other intervention. In the United States, the Federal Deposit Insurance Corporation was created in 1933 to prevent bank insolvency from affecting depositors.
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What is Risk?
Risk is the potential future harm that may arise from some present action. It is often combined or confused with the probability of an event which is seen as undesirable. Usually the probability and some assessment of expected harms must be combined into a believable scenario combining risk, regret and reward probabilities into expected value. There are many informal methods which are used to assess (or to “measure” although it is not usually possible to directly measure) risk, and (for some applications) formal methods such as value at risk.
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