Assessment of Tube Well Pumping Test Performance on Different Geological Formation

Water supply-demand is increasing in line with the increment in population. Natural water resources are declining due to reduction of water catchment areas, river pollution and drought. This causes the raw water quantity and quality to decrease and increase water treatment costs. Groundwater usage may be able to solve this problem due to its less polluted nature which requires less treatment. The groundwater is preserved in aquifer within the geological formations, i.e., in the alluvium and fractured-rock. However, the groundwater yield of each formation is unknown unless tube well is constructed and pumping test are performed. This study aim to evaluate the tube well performance via pumping test on two different geological formations. This research focuses on the effect of transmissivity, hydraulic conductivity, and efficiency of the aquifer, which are step-drawdown test, constant-rate test and recovery test in tube well in geological formation of alluvium and fractured rock. Three well-pumping tests at each formation were conducted at IBS Universiti Malaysia Kelantan (UMK), Kelantan, Sekolah Kebangsaan Chantum, Kelantan, Sekolah Menengah Kebangsaan Agama Tok Bachok, Kelantan, FRU Wakaf Tapai, Terengganu, Kampung Dada Kering, Kuala Lipis, Pahang, and Kampung Seri Gunung Pulai, Johor, respectively. The aquifer efficiency obtained from the relationship between transmissivity and hydraulic conductivity. The suggested value of 75% efficiency is selected to present the well’s efficiency. The wells efficiency indicate that the alluvium formation has roughly uniform output between 9.39m3/h, 11.23m3/h and 23.38m3/h. Meanwhile in the fractured rock formation the efficiency was highly varied between sites, the highest is 32.33m3/h and the other two sites obtained has low output of 3.44 m3/h and 1.00m3/h respectively. The alluvium aquifer showed uniform water production compared to fractured hard rock aquifer. Meanwhile the water quantity in the fractured hard rock formation is unpredicted, which subjected to the fractured rock characteristic.

Automations in Chemostratigraphy: Toward Robust Chemical Data Analysis and Interpretation

Elemental chemostratigraphy has become an established stratigraphic correlation technique over the last 15 years. Geochemical data are generated from rock samples (e.g., ditch cuttings, cores or hand specimens) for up to c. 50 elements in the range Na-U in the periodic table using various analytical techniques. The data are commonly displayed and interpreted as ratios, indices and proxy values in profile form against depth. The large number of possible combinations between the determined elements (more than a thousand combinations), makes it a time-consuming effort to identify meaningful variations that resulted in correlative chemostratigraphic boundaries and zones between wells. The large number of combination means that 30-40% of the information is not used for the correlations that maybe crucial to understand the geological processes. Automation and artificial intelligence (AI) are envisaged as likely solutions to this challenge. Statistical and machine learning techniques are tested as a first step to automate and establish a workflow to define (chemo-) stratigraphic boundaries, and to identify geological formations. The workflow commences with a quality check of the input data and then with principle component analysis (PCA) as a multivariate statistical method. PCA is used to minimize the number of elements/ratios plotted in profile form, whilst simultaneously identifying multidimensional relationships between them. A statistical boundary picking method is then applied define chemostratigraphic zones, for which reliability is determined utilizing quartile analysis, which tests the overlap of chemical signals across these statistical boundaries. Machine learning via discriminant function analysis (DFA) has been developed to predict the placement of correlative boundaries between adjacent sections/wells. The proposed workflow has been tested on various geological formations and areas in Saudi Arabia. The chemostratigraphic correlations proposed using this workflow broadly correspond to those defined in the standard workflow by experienced chemostratigraphers, while interpretation times and subjectivity are reduced. While machine learning via DFA is currently further researched, early results of the workflow are very encouraging. A user-friendly software application with workflows and algorithms ultimately leading to automation of the processes is under development.

Study of migration of radioactive elements in clay layers during the burial of radioactive waste

In 2015, Kazakhstan and the International Atomic Energy Agency (IAEA) signed an agreement to host a low-enriched uranium bank in Ust-Kamenogorsk. In 2019, several batches of enriched uranium were delivered to Kazakhstan and the bank began operations at the Ulba Metallurgical Plant. When transporting and disposing of radioactive elements, there is a need to reduce this possibility by limiting the transfer of uranium from underground storage to underground water. Therefore, in this article, a study was conducted on the migration of radioactive elements in clay layers during the disposal of radioactive uranium waste. There are now many underground repositories (for some types of radioactive waste). These systems are based on different underground container structures for different geological formations. For underground repositories located in geological environments where enriched uranium can migrate, other system components must reduce this possibility by preventing or limiting uranium mobility. This work investigates the process of convective transport of radioactive elements, in a moist soil layer through the installation of an additional natural clay barrier layer, the migration of radioactive elements during safe disposal, the effect of diffusion and convection through the solid waste layer.

Engineering Charts for Predicting Breakdown Pressure for Finite-Length Wellbore Intervals

In wellbore drilling, the drilling mud density needs to be carefully selected such that the mud pressure inside the wellbore will not exceed formation breakdown pressure to avoid wellbore fracturing and extensive mud losses. However, in the hydraulic fracturing treatment, the lesser the value of the formation breakdown pressure the more optimal is the operation. We found out in this study that the pumping schedule (e.g., pumping duration and pumping rate) are factors in optimizing the breakdown pressure. In addition, this work investigates the effects of the finite length between packers on the magnitude of the breakdown pressure in various geological formations. The time-dependent evolving stresses around the wellbore are solved in the framework of time-dependent poroelasticity theory. The breakdown pressure is predicted from the evolution of the circumferential effective stresses. The effects of injection rate, formation properties, borehole diameter and length, and pumping duration on the breakdown pressure are presented in the form of engineering charts, for representative in-situ stress.

Taxonomic and ecological analysis of flora at locality „Djavolja Varoš“ (South Serbia)

Djavolja Varoš, one of the most atractive natural geological formations of errosive origin in Serbia, is situated in the south of the country, and protected by national legislation as a Natural Monument. The taxonomic and ecological analysis of flora in this area has not been processed yet, so we performed a survey of flora in this locality. Plant species were collected, herbarized, and taxonomic and biological spectrum analyses were conducted. This field study revealed that the vascular flora of the study area was made up of 130 constituent species, which belonged to 81 genera and 41 families. The biological spectrum of the flora is characterised by high presence of hemicryphytes (38%) and geophytes (20%).

Characteristics of Carbonate Rocks and Environmental Conditions of Some Caves, Northern Iraq

Six caves were studied in north Iraq, which is the Beeston and Shanidar in Erbil, Garston, Swaratuka, and Ain Ishky in Duhok Governorate, Al-Naqut in Nineveh Governorate. All these caves are located within geological formations of carbonate rocks, limestone, and dolostone. Geotechnical and geometrical measurements were made for these caves, and rocks were sampled from different areas inside and outside the caves. The slake durability of the rocks was measured and thin sections were made, in addition to measuring the percentage of insoluble residues and analyzing the mineral constituents of the collected samples by using X-ray diffraction. By reviewing the geotechnical characteristics and environmental conditions, the Beeston Cave was found to be the oldest of the caves studied because its size is greater than that of the other caves and its rocks have better geotechnical characteristics than the other caves, which means that the time required for it to form is longer. The Al-Naqut Cave was also found to be the newest among these six caves because, in addition to its small size, it has the lowest durability value after the Shanidar Cave and has the lowest value of compressive strength.

Diffusive transport of uranium and americium through clay rock down to ultra-trace levels

Clay rock is a potential host rock for the final disposal of nuclear waste in deep geological formations. In the scenario of ground water intrusion into the nuclear waste repository and subsequent corrosion of canisters and waste, possibly released actinides, such as uranium (U) and americium (Am), would be transported through the engineered barrier and clay host rock mainly by diffusion. Actinides are known to exhibit low solubility and are strongly sorbing under the reducing conditions of deep geological formations. Diffusion experiments are therefore difficult to perform due to analytical constraints. To our knowledge, the diffusion of U in clay rock has not been investigated below concentrations of 10-7molkg-1 clay (e.g., Joseph et al., 2013) and for Am, no diffusion experiments have been performed in a clay rock, considered suitable as host rock, such as Opalinus clay (OPA). This work aimed at the investigation of the diffusive behavior of U and Am down to ultra-trace concentrations (≪10-7molkg-1) in OPA. Laboratory-scale diffusion experiments were conducted with samples of OPA, obtained from the Mont Terri underground laboratory, Switzerland for up to 240 d. The OPA samples were placed in contact with synthetic pore water (I=0.22molL-1, pH=7.24), spiked with 5×10-9molL-1 of 233U and 243Am, respectively. After termination of the experiment, the OPA samples were segmented into thin layers of 20–400 µm. The obtained clay segments were analyzed for the 233U and 243Am content with accelerator mass spectrometry. Concentration profiles were determined down to 10-12molkg-1 clay for 233U and 5×10-10molkg-1 clay for 243Am. U showed a typical diffusion profile which can be interpreted by applying Fick's laws, while the Am profile was more complex, requiring further investigation of transport modes. These results will provide relevant insights into the transport behavior of U and Am in OPA over a wide range of concentrations down to ultra-trace levels.