05.07.2009
A cylindrical or spherical vessel used to separate oil, gas and water from the total fluid stream produced by a well.
The pressure at the bottom of a well when the surface valves on the well are completely closed. It is caused by formation fluids at the bottom of the well.
Semisubmersible rigs are the most common type of offshore drilling rigs, combining the advantages of submersible rigs with the ability to drill in deep water. Semisubmersible rigs work on the same principle as submersible rigs; through the ‘inflating’ and ‘deflating’ of its lower hull. The main difference with a semisubmersible rig, however, is that when the air is let out of the lower hull, the rig does not submerge to the sea floor. Instead, the rig is partially submerged, but still floats above the drill site. When drilling, the lower hull, filled with water, provides stability to the rig. Semisubmersible rigs are held in place by huge anchors, each weighing upwards of ten tons. These anchors, combined with the submerged portion of the rig, ensure that the platform is stable and safe enough to be used in turbulent offshore waters. Semisubmersible rigs can be used to drill in much deeper water than the rigs mentioned above.
Formations at or near the surface, possibly in less than 800 feet of water
Are geophysical information on subsurface rock formations gathered by means of a seismograph; the investigation of underground strata by recording and analyzing shock waves artificially produced and reflected from the subsurface bodies of the rock
Short term contracts in the natural gas field are usually between one month to one year, In the LNG sphere they are also known as Master Sales Agreement and can be on a cargo to cargo basis
The capture of atmospheric carbon dioxide in a solid material
Pressure at the well-head of an exploration or production well when shut in, i.e. not flowing
This is a complex, high technology activity that has its roots in the seismic characteristics of the Earth. Seismology, as practiced commercially in the search for hydrocarbons, is a large and in places very complex subject. The field activity is conducted by advanced survey vessels with typical size of approximately 300ft (5-6000 gross tons), equipped with an energy source (compressed air) to create sound waves and listening cables to register the “echoes” or returned sound waves from the subsurface of the sea bottom. The typical crew onboard the vessel consist of approximately 28 people, of which 12 people are the maritime crew and the rest represents the experts in various disciplines needed to acquire seismic data. The result of the data acquisition is partly analyzed onboard and stored on high capacitive data storage media (Mass Storage System) for further processing and analysis after being received in a data processing centre. The amount of data stored is enormous, for each survey line with approximate length of 23 kilometers typically 7-8 data cartridges are recorded and each cartridge is capable of holding 1 Gigabytes of data. In seismic surveying, energy is generated onboard a survey vessel to produce waves and send them into the earth. This energy wave doesn’t just vanish into the earth’s crust. Some of it is reflected back to the surface and we detect the returning waves with sensitive measuring devices that accurately record the strength of the wave and the time it has taken to travel into the earth’s crust and back to the surface. We can then take these recordings and after various adjustments, done mostly by computers, we can make them into visual pictures that give us a good idea of what the subsurface of the earth is like beneath the seismic survey area. So in summary, we cannot see directly what the rock layers are doing beneath the surface but we can use seismic surveying to get the picture indirectly.