Text 3 Oil and Gas Exploration

Ex.1 Read the text below and decide which word from the box best fits each space.

petroleum geology, offshore, seismic analysis, geologists, wells, prospect, geology, oil exploration, petroleum geologists

­­­­­­­­­ (1) _________ is the science that involves the study of the earth and the earth's origin, composition, structure and history. It is the key to finding new sources of useful earth materials and to understanding earth processes that affect our lives. Scientists who study the origin, history, composition, and structure of the earth and its life as recorded in rocks and other solid matter are called (2) _________.

Because they study earth, people of this profession are important in the search for mineral resources and petroleum. Specialists who are employed by oil companies to determine whether a region may produce oil or gas are called (3) __________.

(4) _________ is the search by petroleum geologists for hydrocarbon deposits beneath the Earth’s surface. Oil and gas exploration are grouped under the science of (5) ___________.

The initial search for oil and gas is carried out with application of many techniques, especially the study of landforms and (6) __________. Where oil is thought likely test (7) _________ will be drilled. A (8) ­­___________ is a potential trap which geologists believe may contain hydrocarbons.

Oil exploration is an expensive, high-risk operation. (9) ____________ and remote area exploration is generally only undertaken by very large corporations or national governments. Typical Shallow shelf oil wells (e.g. North sea) cost $10 - 30 Million.

Text 4 Where to Look for Fields?

sedimentary basins – осадочный бассейн

superimposed layers – слои, наложенные один на другой

valorize, v – повышать цены путем государственных мероприятий

bidder, n – подрядчик, выступающий на торгах

exploration licence – нефтегазопоисковая лицензия

Oil and gas develop in sedimentary basins where superimposed layers of different rocks have accumulated over tens of millions of years. Sedimentary basins are numerous on the surface of our planet. They can be found, of course, at sea, but also on land, in zones that were in the past covered by the sea.

In the early days of the petroleum adventure, nowhere had been drilled: the basins were totally untouched by exploration. Today, virgin basins are very rare. Only a few such zones remain, because their climate aor geography is very hostile, or because they are still protected for ecological reasons, such as in the Antarctic.

Moreover, the sedimentary basins have been more or less explored. Those known for a long time have been the object of numerous drilling operations and are in little danger of revealing new, super-giant deposits or even ones of a biggish size: we say in this case that the exploration is mature. This is the case, for example, in the North Sea.

Can a petroleum company undertake drilling wherever it wants and whenever it wants? No, because what is under the surface of the earth belongs everywhere to the state. This is not only true on land, of course, but also at sea. A country is owner of the mineral resources situated up to 200 nautical miles off its coasts and on the whole of its continental plateau. All the petrol companies are interested in regions where an oil or gas potential exists. They are in competition. And the states, the owners, know it! Therefore, to better valorize their underground riches, these countries put the companies in competition, offering zones for exploration by auctioning them to the highest bidder, under a form of international tender.

Interested companies send in their propositions: an undertaking for the total amount to be spent and for the volume of exploration work to be completed over a given period (in general from 2 to 5 years). The companies often act in groups of associates of 2 or 3 companies, which allows them to share the expenses and the risks if their propositions are accepted. At the due date of the tender operation, the countries examine all the offers and choose the company, or association of companies, that is going to be responsible for drilling the proposed zones. Once a company has obtained the exploration licence, work can begin.

Ex.1 Answer the following questions:

1. Can you describe the rock types where oil deposits are most likely to be found?

2. Where do virgin basins still remain?

3. What does «mature exploration» mean?

4. Who is the owner of underground riches in your country?

5. Why do petroleum companies need the exploration licence?

Text 5

Terms Used in Petroleum Evaluation

Ex.1 Read the text and translate it

resources – балансовые запасы

undrilled prospect – неразбуренный разведуемый участок

appraisal – оценка месторождения

delineation wells – оконтуривающие скважины

oil reserves – запасы нефти

proven reserves- доказанные запасы

probable reserves – вероятные запасы

possible reserves – предполагаемые запасы

hydrocarbon saturation – нефтенасыщенность

Resources are hydrocarbons which may or may not be produced in the future. A resource number may be assigned to an undrilled prospect or an unappraised discovery. Appraisal by drilling additional delineation wells or acquiring extra seismic data will confirm the size of the field and lead to project sanction. At this point the relevant government body gives the oil company a production licence which enables the field to be developed.

Oil reserves are primarily a measure of geological risk - of the probability of oil existing and being producible under current economic conditions using current technology. The three categories of reserves generally used are proven, probable, and possible reserves.

Proven reserves - defined as oil and gas "Reasonably Certain" to be producible using current technology at current prices, with current commercial terms and government consent- also known in the industry as 1P. Some Industry specialists refer to this as P90 - i.e having a 90% certainty of being produced.

Probable reserves - defined as oil and gas "Reasonably Probable" of being produced using current or likely technology at current prices, with current commercial terms and government consent - Some Industry specialists refer to this as P50 - i.e having a 50% certainty of being produced. - This is also known in the industry as 2P or Proven plus probable.

Possible reserves - i.e "having a chance of being developed under favourable circumstances" - Some industry specialists refer to this as P10 - i.e having a 10% certainty of being produced. - This is also known in the industry as 3P or proven plus probable plus possible.

Chance of Success - An estimate of the chance of all the elements within a prospect working, described as a probability. High risk prospects have a less than 10% chance of working, medium risk prospects 10-20%, low risk prospects over 20%. Typically about 40% of wells recently drilled find commercial hydrocarbons.

Hydrocarbon in Place - amount of hydrocarbon likely to be contained in the prospect. This is calculated using the volumetric equation - GRV x N/G x Porosity x Sh x FVF

• GRV - Gross Rock volume - amount of rock in the trap above the hydrocarbon water contact

• N/G - net/gross ratio - percentage of the GRV formed by the reservoir rock ( range is 0 to 1)

• Porosity - percentage of the net reservoir rock occupied by pores (typically 5-35%)

• Sh - hydrocarbon saturation - some of the pore space is filled with water - this must be discounted

• FVF - formation volume factor - oil shrinks and gas expands when brought to the surface. The FVF converts volumes at reservoir conditions (high pressure and high temperature) to storage and sale conditions

Recoverable hydrocarbons - amount of hydrocarbon likely to be recovered during production. This is typically 10-50% in an oil field and 50-80% in a gas field.