Carbonate reservoir distribution

The content of the material in a carbon reservoir is a measure of that reservoir s direct or indirect exchange rate with the atmosphere, although variations in solar also create variations in atmospheric content activity (Stuiver and Quay, 1980, 1981). Geologically important reservoirs (i.e., carbonate rocks and fossil carbon) contain no radiocarbon because the turnover times of these reservoirs are much longer than the isotope s half-life. The distribution of is used in studies of ocean circulation, soil sciences, and studies of the terrestrial biosphere. 

Table I. Distributions of Natural 14C and of Excess 14C in the Several Carbon Reservoirs at the End of 1962...

Obviously this wide distribution of the 14C formed in the atmosphere lakes time it is believed to require a period of 500-1000 years. This time is not. however, a deterrent to radiocarbon dating because of two factors die long half-life of I4C and the relatively constant rate of cosmic-ray formation of l4C in the earth s atmosphere over the most recent several thousands of years. These considerations lead to the conclusion that the proportion of 14C in the carbon reservoir of the earth is constant, and that the addition by cosmic ray production is in balance with the loss by radioactive decay. If this conclusion is warranted, then the carbon dioxide on earth many centuries ago had the same content of radioactive carbon as the carbon dioxide on earth today, Thus, radioactive carbon in the wood of a tree growing centuries ago had the same content as that in carbon oil earth today. Therefore, if we wish to determine how long ago a tree was cut down to build an ancient fire, all we need to do is to determine the relative 14C content of the carbon in the charcoal remaining, using the value we have determined for llie half life of 14C. If the carbon from Ihe charcoal in an ancient cave has only as much 14C radioactivity as does carbon on earth today, then we can conclude that the tree which furnished llie firewood grew 5730 30 years ago. 

Acid-in-oil emulsion can extend the propagation of acid considerable distances into a reservoir because the continuous (oil) phase prevents or minimizes contact between the acid and the rock [4,678,689]. Emulsification also increases viscosity and will improve the distribution of the acid in layered and heterogeneous reservoirs. Acidizing foams are aqueous, in which the continuous phase is usually hydrochloric acid (carbonate reservoirs) or hydrofluoric acid (sandstone reservoirs), or a blend, together with suitable surfactants and other stabilizers [345,659]. Foaming an acidizing fluid increases its effective viscosity, providing mobility control when it is injected [678]. 

Variability in the Amount of Carbon in Reservoirs. In addition to variations in the production and distribution of radiocarbon over time and within portions of various carbon reservoirs, variations may result in situations where carbon not in equilibrium with the contemporary standard values is added or removed from any reservoir. Two instances of this are well documented since they occurred within the last century as a result of human intervention. The first is known as the industrial or Suess effect and is caused by the combustion of fossil fuels beginning about 1890, resulting in a depletion of atmospheric activities by about 3% (76). A more recent occurrence has been called the atomic bomb or Libby effect. The detonation of nuclear devices in the atmosphere beginning in 1945 produced large amounts of artificial increasing the radiocarbon concentrations in the atmosphere by more than 100% in the Northern Hemisphere (77). Because of equilibration with the oceans, the levels have been diminishing steadily since the atmospheric testing was terminated by the major nuclear powers except France and the People s Repub-... 

The half-life of these C atoms is 5,730 years. Hence, they have on average 8,270 years to distribute themselves through the Earth s active carbon reservoirs. Radiocarbon atoms decay by emitting an electron, thereby converting a neutron to a proton returning the nucleus to its original form. 

Figure 13 shows an estimate as to how the distribution of bomb radiocarbon atoms among these active carbon reservoirs has evolved. 

Chilingar, G.V., 1964. Relationship between porosity, permeability, and grainsize distribution of sands and sandstones. In Van Straaten, L.M.J.U. (ed.) Deltaic and shallow marine deposits I. Elsevier, Amsterdam, pp. 71-75 Chilingarian, G.V., Mazzullo, S.J. and H.H. Rieke, 1992. Carbonate reservoir characterization a geologic - engineering analysis, part I, Developments in Petroleum Science 30, Elsevier, Amsterdam, 639 pp. 

Fig. 4. A number of oils from the Rimbey-Meadowbrook reef trend in east-central Alberta have been characterized for wax content. HTGC chromatograms for three of these oils sourced from the Duvemay Formation are shown in this figure. Note that as these oils migrate to the shallower reservoirs, the wax content decreases and the carbon number distribution moves to lower carbon numbers as a result of depositions of the higher carbon numbered components.

Heasley, E. C., Worden, R. H. Hendry, J. P. 2000. Cement distribution in a carbonate reservoir recognition of a palaeo oil-water contact and its relationship to reservoir quality in the Humbly Grove field, onshore, UK. Marine and Petroleum Geology, 17, 639-654. 

An effective acid diversion technique is needed to overcome uneven acid distribution and obtain good sweep efficiency during stimulation. Mechanical and chemical means are available for acid diversion. Mechanical means include straddle packers and ball sealers, however, they have limited use in openhole, gravel packed and slotted liner completions and are normally expensive [66]. Chemical means can be used in cased and openhole wells. The type of chemical diversion technique depends on the lithology and other reservoir characteristics (temperature, salinity, and hydrogen sulfide content). In carbonate reservoirs, emulsified acids [J6] and viscosity controlled acids [67] have been used to improve sweep... 

Budgets and cycles can be considered on very different spatial scales. In this book we concentrate on global, hemispheric and regional scales. The choice of a suitable scale (i.e. the size of the reservoirs), is determined by the goals of the analysis as well as by the homogeneity of the spatial distribution. For example, in carbon cycle models it is reasonable to consider the atmosphere as one reservoir (the concentration of CO2 in the atmosphere is fairly uniform). On the other hand, oceanic carbon content and carbon exchange processes exhibit large spatial variations and it is reasonable to separate the... 

However, with "only" 1000 Pg emitted into the system, i.e. less than 3% of the total amount of carbon in the four reservoirs, the atmospheric reservoir would still remain significantly affected (20%) at steady state. In this case the change in oceanic carbon would be only 2% and hardly noticeable. The steady-state distributions are independent of where the addition occurs. If the CO2 from fossil fuel combustion were collected and dumped into the ocean, the final distribution would still be the same. 

Pearman, G. I. and Hyson, P. (1986). Global transport and inter-reservoir exchange of carbon dioxide with particular reference to stable isotopic distributions, /. Atm. Chem. 4, 81-124. 

Radiocarbon is uniformly distributed in the carbon exchange reservoir. 

Significant economies of computation are possible in systems that consist of a one-dimensional chain of identical reservoirs. Chapter 7 describes such a system in which there is just one dependent variable. An illustrative example is the climate system and the calculation of zonally averaged temperature as a function of latitude in an energy balance climate model. In such a model, the surface temperature depends on the balance among solar radiation absorbed, planetary radiation emitted to space, and the transport of energy between latitudes. I present routines that calculate the absorption and reflection of incident solar radiation and the emission of long-wave planetary radiation. I show how much of the computational work can be avoided in a system like this because each reservoir is coupled only to its adjacent reservoirs. I use the simulation to explore the sensitivity of seasonally varying temperatures to such aspects of the climate system as snow and ice cover, cloud cover, amount of carbon dioxide in the atmosphere, and land distribution. 

C02, HC03 and C03 in the ocean. Figure 7 shows the different reservoirs with their relative amounts of carbon. 14C is produced in the atmosphere, and by exchange and mixing it gets distributed in the entire carbon system. The preindustrial 14C/C ratio of the carbon in the mixed ocean surface layer is estimated to have been... 

If the stable isotope ratio of 13C/12C is to be further measured in tree rings and interpreted as an indicator of climate variation, (and we have barely begun to initiate its use as a thermometer in the present work, confining our measurements to the stable isotopes in water, because water is so abundant compared to carbon dioxide and because the dependence of its isotope ratios is relatively simple compared with those of carbon dioxide), some more sophisticated considerations must be given to the distribution of carbon dioxide among the reservoirs on the surface of the earth. 

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