Papers by Keyword: Carbonate Rocks

Abstract: The experimental studies’results of the structure and properties of cellular concrete with one-stage preparation of foam concrete mixtures are presented. The effect of the filler on the foam concrete properties has been evaluated. The possibility of producing high-quality chalk foam concrete from soft crushed chalk with a fraction of 2.5 mm has been proven. The influence of the slip viscosity, the type and amount of the foaming agent, the type of cement on the properties of small foam concrete has been established.

Abstract: Some carbonate reservoirs are known for their high CO₂ content in oil. One possibility to handle this gas without environmental problems is to reinject it into the reservoir. Injection of carbonated water has been drawing attention because it is an advantageous technique when compared to gaseous CO₂ injection, due to its improvement in mobility in the reservoir. The objective of this study is to evaluate the phenomenon of dissolution and precipitation during carbonated water injection in carbonate rocks. These effects are identified by analyzing the porosity variations through X-ray computer tomography images and permeability profile, determined indirectly by pressure transducers that measured the differential pressure by the fluid at the inlet and outlet of the core holders. The Coreflooding test were carried out with two core holders in series to represent a near region at the reservoir by the injection of brine saturated with 25% of CO₂ in reservoir samples, composed of dolomite, calcite and clay. The test were performed using the following reservoir conditions of 8,500 psi at 70°C. Based on the experimental data provided by CT images, it can be seen that the core porosity increases or decrease during carbonated water injection due to coexistence of dissolution (increase of porosity) and precipitation (decrease of porosity) along the samples. These phenomena are observed in regions with high heterogeneity in porosity. In addition, the mineralogy of the cores is composed by three minerals, which influence in the capacity of reaction with carbonated water. For the experiment, the core placed in the core holder one presented a porosity increase and the second one decreased. On the other hand, the permeability showed a significant increase for both cores, it is believed that, the injection promoted a preferential way flow (wormhole) that affected considerably the permeability of the rock. The novelty of the investigation is that the experiments were carried out using Brazilian pre-salt carbonate reservoir rocks with mineralogy composed basically by dolomite, calcite and clay. Also, experimental work was performed at reservoir operational conditions.

Abstract: In accordance with low success ratio of lithology identification in carbonate formation, a made of Identifying lithology of carbonate rocks through fuzzy mathematics has set up. 8 logging parameters reflecting lithology of carbonate rocks were selected and threshold values were determined. Lithologies of carbonate rocks were classified by using this identification mode and maximum subordination principle. Using field data identified 10 types of carbonate rocks, and they were compared with the result of core analysis, showing 85 % consistency. Therefore this method has higher accuracy for identification of carbonate lithology, and is quite promising in geological application.

Abstract: In oil and gas exploration of Block K in Amu Darya basin Uzbekistan, the reservoir lithologies are mainly in different carbonate rocks, the more types of rocks, the more various reservoir space is, as a result, it brings some difficulties to the reservoir quantitative evaluation. Therefore, according to this situation that the difficulty in identification of complex carbonate lithologies is, in this study block, artificial neural network analysis method is used in this paper. The method combines mud logging, cutting, core data, well logging, studies logging response characteristics of the different types of carbonate rocks, establishes lithology identification index. In this study, the method is used in identifying the types of carbonate rocks, the identified result compared to actual rocks displays about 70.51~87.23%, and it plays the positive role for reservoir quantitative evaluation.

Abstract: The reservoir of Lianglitage formaton mainly distribute in the Liang 1~Liang 2 section, and slight amount distribute in Liang 3 section. The microfacies are abundant and, and they apparently affect the development of the reservoir. Based on the geologic feature, we propound the concept:"microfacies combination". It is composed by two or several microfacies, and each microfacies have similar reservoir conditions. Using the seismic facies interpretation, combining the methods of deterministic modeling and stochastic modeling, the "microfacies combination" model is established. Appling the method that "microfacies combination" controls the modeling course, taking the wave impedance which has good corresponding relationship with reservoir as secondary variable, small layer application of stochastic modeling method based on the porosity model is finally established through the stochastic modeling method layer and layer. Considering the crack influence on permeability, the first step is establishing the fracture distribution model, then the permeability model is established taking the fracture distribution as secondary variable, which improves the practicability of permeability model.

Abstract: Pattern recognition of carbonate rocks in RS image have been studied in the paper. Samples of carbonate rocks were scanned into rock images.By analysing these samples of carbonate rocks,a new arithmetic was chosed and a standard curve of carbonate rocks by the arithmetic can be gotten.Rs images were divided into grids.There are curves by the arithmetic in grids. The standard curve of carbonate rocks and curves in grids were compared.If both of curves look very similar,the grid is carbonate rocks area.

Abstract: There are significant impacts on the safty of tunnels because of porous materials.In order to avoid serious accidents of tunnels, Porous materials of carbonate rocks under the condition of low temperature and high pressure have been studied in the paper. Samples of local carbonate rocks have been collected from carbonate rock formation. Special machine was designed to simulate the condition of low temperature (10°C-20°C ) and high pressure (1-30Mpa) undergroud 4000M in jinping.Samples of local carbonate rocks have been tested in the machine. Spectrographs and scanners have been used to observed the change of porous materials of carbonate rocks.Results of the technological measurements show that the change of porous materials of carbonate rocks is affected by low temperature and high pressure.With the change of low temperature and high pressure, surface chemistry is affected throughout the surface of carbonate rocks. When the temperature of carbonate rocks exceed 15°C and pressure less than 18Mpa,there will be new compounds on the surface of carbonate rocks. These new compounds will change the porosity and thesaturated permeability of carbonate rocks.The change may led to serious accidents of tunnels.If we want to avoid these serious accidents,we must keep the temperature of carbonate rock formation less than 15°C and pressure exceed 18Mpa.