Limestone reservoir

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 ... 

Increase of reservoir permeability and widening of the fissures and channels through the etching of carbonaceous rocks in limestone reservoirs by organic acids produced by anaerobic bacteria... 

Other wells in the same field had shown a limestone reservoir of fair permeability, with major tectonic faults and some associated fissures. Well data were provided by the operator. The low value of the wellbore storage demonstrates no coupling of the well with secondary porosity. However, the operator suspected the presence of some kind of fault not far from Well B, whose production test was unusual. He decided to acidize in an attempt to establish communication. 

Properties and extraction processes Tight-formation gas is natural gas trapped in low-porosity (7 to 12%), low-permeability reservoirs with an average in-situ permeability of less than 0.1 millidarcy (mD), regardless of the type of the reservoir rock tight gas usually comprises gas from tight sands (i.e., from sandstone or limestone reservoirs) and shale gas. Sometimes tight gas also comprises natural gas from coal and deep gas from reservoirs below 4500 m. Shale gas is produced from reservoirs predominantly composed of shale rather than from more conventional sandstone or limestone reservoirs a particularity of shale gas is that gas shales are often... 

Lens-Type Traps. These form in limestone and sand. In this type of trap the reservoir is sealed in its upper regions by abrupt changes in the amount of connected pore space within a formation. A trap formed in sand is shown in Fig, 7(a). An example is the Burbank Field in Osage County, Oklahoma. This type of trap may occur in sandstones where irregular deposition of sand and shale occurred at the time the formation was laid down. In these cases, oil is confined within the porous parts of the rock hy the nonporous parts of rock surrounding it. A lens-type trap formed in limestone is shown in Fig. 7(b). In limestone formations there are frequent areas of high porosity with a tendency to form traps. Examples of limestone reservoirs of this type are found in the limestone fields of West Texas. 

The Coaraze site, located in the coastal part of the French Alps, consists of a small limestone reservoir with a volume of approximately I9,0(X) m drained by a spring running at an annual mean flow rate of 10 1/sec (see Fig. 1). This spring has been equipped with a valve that, when closed, causes water to rise in the rock mass until reaching a height of approximately 10 m. The evolution in hydromechanical behavior of the fractures within the saturated zone is recorded by variations in both water pressure and time, Guglielmi (1999). 

MANY LIMESTONE RESERVOIRS High porosity, low pormeability... 

Oil Weekly. December 19 70. Clason, C. E., and J. G. Staudt. 1935. Limestone reservoir rocks of Kansas react favorably to acid treatment. 

Bituminous sand a formation in which fhe bifuminous material (see Bitumen) is found as a filling in veins and fissures in fractnred rocks or impregnating relatively shallow sand, sandstone, and limestone strata a sandstone reservoir that is impregnated with a heavy, viscons black petroleumlike material that cannot be retrieved throngh a well by conventional production techniqnes. 

The crust is the largest carbon reservoir in the crustal-ocean-atmosphere factory (8 x 10 Pg C including the sediments). Most of this carbon is in the form of inorganic minerals, predominantly limestone, with the rest being organic matter, predominantly contained in shale and secondarily in fossil fuel deposits (coal, oil, and natural gas). The oceanic reservoir (4 X lO" Pg C) and the terrestrial reservoir (2 to 3 x 10 Pg C) are both far smaller than the crustal reservoir. The smallest reservoir is found in the atmospheric, primarily as CO2 (preindustrial 6 x 10 Pg C, now 8 x 10 Pg C and rising). The flux estimates in Figure 25.1 have been constrained by an assumption that the preindustrial atmospheric and oceanic reservoirs were in steady state over intermediate time scales (millennia). 

Earths land reservoirs play an important role in long-term carbon storage. In fact, they store carbon for very long periods of time. The carbon in limestone, for example, may remain in a land reservoir for thousands of years. The carbon in a fossil fuel may be stored for millions of years. 

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