MTEI and Finding Old Oil , pt 1:
We are starting to get some good info on the company and its known assets in WVA. I thought I would look ahead a little bit and get some info on the oil intentions of the company. Again, being personally ignorant, part 1 is basic stuff:
From MTEI Press Release: Thursday May 28, 1998
Many Gulf Coast oil and gas fields have never been evaluated with advance logging tools that can detect previously overlooked and untested hydrocarbon-bearing formations that lie behind casing pipe. Most of the major oil and gas fields Gulf Coast region were discovered between 1930 and 1970 and were logged with simple electric logging equipment. Wells were lined with steel casing down to the objective formation depth to prevent shallower formations from collapsing into the wellbore. Until the recent emergence of superior case hole logging technology and digital log re-processing, it was difficult to identify hydrocarbon bearing formations behind cased wellbores.
Oil Drilling Explained:
sopc.com
Drilling for oil is a highly skilled operation often carried out in remote areas and hostile environments. If the find is promising and commercial conditions are right, a field will be developed and brought into production.
During the production phase, good reservoir management ensures that the oil is produced as efficiently as possible. In recent years, increasing attention has been focused on finding and producing oil offshore, where, thanks to engineering and technological advances, it is possible to operate in deeper and more hostile waters than ever before.
Wells are drilled with rotary drilling tools which work on the same principle as the carpenter's brace and bit. The cutting tool is the drilling bit which has tough metal or sometimes diamond teeth that can bore through the hardest rock. The bit is suspended on a drilling string consisting of lengths of pipe, which are added to as the bit goes deeper. The bit is turned either by a rotary table on the drill floor or, increasingly, by a downhole motor.
In time, the bit gets worn and has to be replaced. The whole drilling string, sometimes weighing over 100 tons, must then be hauled to the surface and dismantled section by section as it emerges. The new bit is fitted and slowly lowered as the drill pipe sections are re-assembled. This operation, known as a 'round trip', can in a deep well, take most of a 12 hour shift. Until recently, the drilling string was mostly manually handled by the drilling crew. In order to improve safety and reduce drilling costs, automated drilling rigs with mechanized pipe handling and computerized controls are being introduced. One of the essential supplies for the drilling crew is 'mud', or drilling fluid. This is a special mixture of clay, various chemicals and water, which is constantly pumped down through the drill pipe and comes out through nozzles in the drilling bit. The stream of mud returns upwards through the space between the drilling string and the borehole, carrying with it rock fragments cut away by the bit. At the top, the returned mud is sieved and then recirculated through a pump. The cuttings left on the sieve indicate the kind of rock the drill is passing through and they may show traces of oil as the bit nears an oil-bearing formation. The drilling mud keeps the bit cool and prevents the escape of gas or oil when the bit enters an oil trap.
The drilling rig is a substantial piece of equipment and before drilling can start in remote areas, roads may have to be built through jungle and across desert to provide access. To reduce transport cost, initial exploration wells in remote areas may nowadays be drilled by much smaller, slimhole rigs.
The rate of drilling varies with the hardness of the rock. Sometimes the bit may cut through as much as 200 feet an hour, but in a very hard layer progress may be as little as one foot an hour. Most oil wells are between 3,000 and 16,500 feet deep but wells as deep as four or five miles are sometimes drilled.
Whenever possible, wells are drilled vertically, but sometimes, especially offshore, it is necessary to deviate from the vertical in order to reach a wide spread of targets from a single platform. This is known as 'directional drilling'. Recent developments have made it possible to deviate as much as 90 degrees from the vertical. Known as 'horizontal drilling', this technique can, in some instances, increase the productivity of a well. See a graphical description of this.
Special care is needed during drilling as the bit nears a formation containing oil and gas. The high pressure in an oil trap may force oil and gas up to the surface in a violent surge as the drill breaks through the impermeable rock.
Such 'blow-outs' or 'gushers' were common in the early days of the oil industry, but drilling technicians are now trained to prevent them, as they pollute the environment, carry a high fire risk and waste hydrocarbons. The supervisor in charge of drilling can anticipate the danger of a blow-out occurring when rock chippings from the well bottom show traces of oil, or when instruments on the derrick floor show rising pressures in the well. He can pump down heavier drilling mud to hold back the oil or close special valves, known as blow-out preventers, fitted to the top of the well casing.
During drilling operations, valuable information about the field at various depths is collected by a procedure known as 'logging'. Drill cuttings which are returned to the surface are examined for traces of hydrocarbons and for their fossil content. Wireline logs examine the electrical, acoustic and radioactive properties of the rocks which give clues as to the rock type, its porosity and how much fluid it contains.
Advanced drilling by Mobil:
mobil.com
Mark N.
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