3-barrel

During loading and unloading of crude oil tankers, the specific gravity of the crude is measured to confirm it meets the specifications for the case where payment is made on a barrel basis, or when the volume is converted into weight if the transaction is based on a price per ton (Hayward et al., 1980). 

For example, the many deepwater fields located in the Gulf of Mexico are of Tertiary age and are comprised of complex sand bodies which were deposited in a deepwater turbidite sequence. The BP Prudhoe Bay sandstone reservoir in Alaska is of Triassic/ Cretaceous age and was deposited by a large shallow water fluvial-alluvial fan delta system. The Saudi Arabian Ghawar limestone reservoir is of Jurassic age and was deposited in a warm, shallow marine sea. Although these reservoirs were deposited in very different depositional environments they all contain producible accumulations of hydrocarbons, though the fraction of recoverable oil varies. In fact, these three fields are some of the largest in the world, containing over 12 billion barrels of oil each ... 

If the reservoir pressure remains above the bubble point then any gas liberated from the oil must be released in the tubing and the separators, and will therefore appear at the surface. In this case the producing gas oil ratio (Rp) will be equal to R. i.e. every stock tank barrel of oil produced liberates Rs scf of gas af surface. 

Keywords d rec methods, indirect methods, rock properties, coring, core barrel, standard core analysis, special core analysis, slabbed core, sidewall samples, direct indications, microfossils, sonde, logging unit, invasion, mudcake, formation pressure measurement, fluid sampling, measurement while drilling, formation evaluation while drilling. 

Coring is performed in between drilling operations. Once the formation for which a core is required has been identified on the mud log, the drilling assembly is pulled out of hole. For coring operations a special assembly is run on drill pipe (Fig. 5.33) comprising a core bit and a core barrel. 

If a conventional core has been cut, it will be retrieved from the barrel on the rig floor and crated. It is common to do a lithologic description at this stage. To avoid drying out of core samples and the escape of light hydrocarbons some sections will be immediately sealed in a coating of hot wax and foil. 

The following diagram represents underground volumes of fluid produced. The relationship between the underground volumes (measured in reservoir barrels) and the volumes at surface conditions is discussed in Section 5.2. The relationships were denoted by... 

The legs of the platform can be used as settling tanks or temporary storage facilities for crude oil where oil is exported via tankers, or to allow production to continue in the event of a pipeline shut down. The Brent D platform in the North Sea weighs more than 200,000 tonnes and can store over a million barrels of oil. Topside modules are either installed offshore by lift barges, or can be positioned before the platform is floated out. 

The process capability for FPSOs is up to some 100,000 barrels per day, with storage capacity up to 800,000bbls. 

In 1986 when the oil price crashed to 10 a barrel, operators began to look very hard at the requirements for offshore developments and novel slimline, reduced facilities platforms began to be considered. The reduced capital outlay and early production start up capability, coupled with the added flexibility, ensured that all companies now consider subsea systems as an important field development technique. Although the interest and investment in subsea systems increased dramatically, subsea systems still had to compete with the new generation of platforms, which were becoming lighter and cheaper. 

Figure 13.4 Split of the barrel under a typical tax and royalty system...

This method attempts to relate the capital allowance to the total life of the assets (i.e. the field s economic lifetime) by linking the annual capital allowance to the fraction of the remaining reserves produced during the year. The capital allowance is calculated from the unrecovered assets at the end of the previous year times the ratio of the current year s production to the reserves at the beginning of the year. As long as the ultimate recovery of the field remains the same, the capital allowance per barrel of production is constant. However, this is rarely the case, making this method more complex in practice. 

Per barrel costs (costs per barrel of development production) are useful when production is the constraint on a project, or when making technical comparisons between projects in the same geographical area. 

In Section 13.2, it was suggested that opex is estimated at the development planning stage based upon a percentage of cumulafive capex (fixed opex) plus a cosf per barrel of hydrocarbon production (variable opex). This method has been widely applied, with the percentages and cost per barrel values based on previous experience in the area. One obvious flaw in this method is that as oil production declines, so does the estimate of opex, which is nof the common experience as equipment ages it requires more maintenance and breaks down more frequently. 

A considerable percentage (40% - 85%) of hydrocarbons are typically not recovered through primary drive mechanisms, or by common supplementary recovery methods such as water flood and gas injection. This is particularly true of oil fields. Part of the oil that remains after primary development is recoverable through enhanced oil recovery (EOR) methods and can potentially slow down the decline period. Unfortunately the cost per barrel of most EOR methods is considerably higher than the cost of conventional recovery techniques, so the application of EOR is generally much more sensitive to oil price. 

Godzik A, J Skolnick and A Kolinski 1992. Simulations of the Folding Pathway of Triose Phosj Lsomerase-type a// Barrel Proteins. Proceedings of the National Academy of Sciences USA 89 1 2633. 

In the United States, the first commercial petroleum deposit was discovered in 1859 near Titusville in western Pennsylvania when Edwin Drake and Bill Smith struck oil in their first shallow (—20 m) well. The well yielded some 400 gallons of oil per day (about 10 barrels). 

Proven oil reserves, instead of being depleted, as a matter of fact, tripled over the last 30 years and now are a trillion barrels. Natural gas reserves have grown even more. This seems so impressive that most people assume that there can be no oil or gas shortage in sight. However, inevitably increasing consumption by a growing world population... 

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