Limestone formation

A karst structure . e. a limestone formation which has been eroded resulting in a large scale, open system comparable to a cave... 

Petroleum. Citric acid is added to hydrochloric acid solutions in acidising limestone formations. Citric acid prevents the formation of ferric hydroxide gel in the spent acid solution by chelating the ferric ions present. Formation of the gel would plug the pores, preventing the flow of oil to the producer well (123—127). 

A particular problem in oil recovery arises in the acidising process for stimulating well production in limestone formations . For many years 15% hydrochloric acid for this process has been successfully inhibited with commercially available organic inhibitors to minimise attack on the... 

Filter. A filter is used in some cases when coagulation and sedimentation do not completely separate the solids from the liquid waste in areas where sand and sandstone formations are susceptible to plugging. Filters with a series of metal screens coated with diatomaceous earth or cartridge filters are typically used.27 Where limestone formations with high solution porosity are used for injection, filtration is usually not required. 

In Gubbio, Italy, a 1 cm layer of clay between extensive limestone formations marks the boundary between the Cretaceous and Tertiary Periods. This clay layer was known to have been deposited about 65 million years ago when many life forms became extinct, but the length of time associated with the deposition was not known. In an attempt to measure this time with normally deposited meteoritic material as a clock, extensive measurements of iridium abundances (and those of many other elements) were made on the Gubbio rocks. Neutron activation analysis was the principal tool used in these studies. About 50 elements were searched for in materials like the earth s crust, about 40 were detected and about 30 were measured with useful precision [26-28]2. 

The Lower Jurrasic deposits include the detritic formation (Hettangian - Lower Sinemurian), the limestone formation (Upper Sinemurian - Pliensbachian) and the marl formation with ammonites and belemnites (Toarcian). 

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. 

Early humans doubtless found elemental sulfur in volcanic craters, encrusting the edges of hot sulfur springs, and embedded in limestone formations. They discovered that it would bum and used it for medicinal purposes, as a bleach, as a fumigant, as a colorant, and as incense. Its use for these purposes is mentioned in ancient writings. The Romans produced incendiary weapons from sulfur. In the thirteenth century, the Chinese invented gunpowder using sulfur, nitrate, and charcoal. 

Fig. 20. Distribution of localities connected with the freshwater limestone formations of the Castle Hill of Buda. Numbers refer to houte numbers (see the text) the Hilton locality is indicated separately.

Nierode, D.E., and Williams, B.B. Characteristics of acid reaction in limestone formations. Soc. Petrol. Eng. Jour. Trans. 251, 406-418 (1971). 

Both the limestone formation and the corrosion had to be dealt with. Since CaC03 contains the basic anion C032-, acid dissolves limestone ... 

When snrface water dissolves carbon dioxide, carbonic acid (H2CO3) is formed. When the water moves undergronnd throngh limestone formations, the limestone dissolves and caves are sometimes produced. 

If the producing zone of a well is in a limestone formation, acidizing techniques may be used to stimulate production [23]. Corrosion-inhibited hydrochloric acid is pumped down the well, which dissolves the limestone with which it comes into contact and in this way generates new channels for oil flow (Eq. 17.1). 

The geology of the area should be known in as much detail as possible. There should be as few faults as possible, with no history of seismic disturbances. Limestone formations should be avoided. The land should be flat with possibly one hill for air dispersion, and there should be tree and shrub coverage to keep dust down. 

Moss, S. Tucker, M.E. (1995) Diagenesis of Barremian-Aptian platform carbonates (the Urgonian Limestone Formation of SE France) near-surface and shallow-burial diagenesis. Sedimentology, 42, 853-874. 

The third equation above describes a reaction that helps the oil industry extract more oil from a well. For oil to be pumped from deep in the earth to the surface, it must first seep through underground rock formations to the base of the oil well s pipes. Limestone, which is composed of CaC03, can be made more permeable to oil by pumping hydrochloric acid down into the limestone formations, converting the insoluble calcium carbonate to soluble calcium chloride. 

As you saw in the last section, the calcium carbonate in limestone can be converted into calcium oxide (lime) and carbon dioxide. At normal temperatures, this reaction is so slow that most limestone formations remain unreacted for thousands of years. Why, then, does it take place rapidly at 1200 °C Similarly, why does the combustion of gasoline take place more quickly when the fuel air mixture in a cylinder of your car is compressed into a smaller volume by a moving piston How does your car s catalytic converter speed the conversion of NO( g ) into N2(j ) and 02 g) Now that we know more about the requirements for reaction, we can proceed to answer questions such as these. 

In dolomite, add spends differently than in limestone formations. The readion of HC1 with dolomite is rate-limited at formation temperatures under 50 °C. Wormhole development, which is common in limestone acidizing, is not charaderistic in dolomite addizing (32). As pores become connected during matrix addizing operations, dolomites form caverns. The use of foamed acid ensures that the acid is spent in the primary channels and allows deeper penetration. Foams are good acid extenders. Deeper penetration can be achieved with foamed add as opposed to an equal volume of nonfoamed acid. 

Acid spending, dolomite versus limestone formations, 379... 

Saunders (110) has shown that the intensities of the peaks in the TL curves increased with increase in depth in a Niagara limestone deposit. The glow curves were useful for studying the various strata of the deposit. Parks (111) reported a similar study relating TL curves of the samples with the identification and characterization of a formation, the identification of the top and bottom of limestone formations, and the characterization of erosion or nondeposition of zones. 

There are numerous natural underground cavities, such as caves in limestone formations, which might conceivably be used for the containment of carbon dioxide, although there is always the risk that pressurized gas will leak out... 

At a depth of 500 m and with a thickness of 130 m, the argillites under study have an initial permeability less then lO m/s, with overlying and underlying limestone formations remaining relatively impermeable. The porosity of the argillites varies from 13 to 17%. 

Micro piles (a.k.a. mini piles) of diameter 150-300 mm are used especially for underpinning of existing structures in distress, as well as support for structures (buildings and bridges) in difficult ground conditions, particularly in shallow karsts limestone formations, boulders in granite formations as well as soft ground over shallow hard formation (Ooi et al. 2004). 

In special circumstances such as footing for tank on soft alluvial ground, or deep basement with heavy loads over karstic limestone formation, raft and pile raft foundations, and barrette piles are used. To overcome the potential danger from slump zone at the contact between the pile toe and the limestone, compaction grouting is often carried out to infill the slump zone. 

The Sr/ Sr ratios of two Cambrian limestone formations of known marine origin (i.e., the Nelson Limestone, Pensacola Mountains, and limestone of the Leverett Formation, Mt. Webster, Harold Byrd Mountains) are both consistent with the Sr/ Sr ratio of Cambrian seawater. In addition, the Sr/ Sr ratio of one carbonate sample from the Triassic Fremouw Formation plots close to the seawater curve... 

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