Hydro-Geophysical Study for Well Design in Lower Reaches of Kasai River Basin, Eastern India

Saltwater intrusion and up coning in coastal aquifer is a common phenomenon brought either due to flow of seawater into freshwater aquifer originally caused by groundwater abstraction near the coast or due to wrong casing design of water wells. This necessitates a study of aquifer disposition along with demarcation of fresh water saline water interface of Kasai River basin, Eastern India to determine the depth to freshwater and recommend the borehole design. In this study geophysical and hydrogeological techniques were employed to map to demarcate fresh and saline water interface. The phenomenon of saline water up coning is also noticed and accordingly water wells have been designed. For the said study, twenty two geophysical logs, sixty five lithological logs and hydrogeological data of eighty eight sites spread across Kasai River basin were utilized. The study shows that there are three regional aquifers exist in the area. It is recommended that water wells in the study area is to be constructed with artificial gravel packing of size 2-3mm and screen slot size is suggested to be 1.2mm. Since the sites are affected with saline water, hence isolation of zone is mandatory with proper cementing material or packer. This research work is able to develop a design model for the boreholes located in the area. The work as a whole will serve as a vital role in scientific management of groundwater resource and enable the rational planning in coastal aquifers so as to avoid fresh and saline water intermixing and up-coning.

Peculiarities of performance of experimental filtering works in sites subsoil operated by single water intakes

The article discusses the methods used in the field experimental filtration work, which allow you to gain knowledge about the filtration properties and water abundance of rocks. The features of the experimental filtration work in the subsoil areas operated by single water intakes are shown. It is noted that these are small water bodies, both in terms of the number of water wells and the amount of actual water withdrawal. The article proposes to use short-term single pumpings as a field research method in the above-mentioned areas, according to the results of which it is possible to substantiate the amount of required water withdrawal and determine the calculated values of the water conductivity coefficient. As an example, the results of pumping are considered, obtained during the implementation of experimental filtration work at three single water intakes located within the Latitude Ob region. The results of the experimental filtration work served as the source material for calculating the reserves of fresh groundwater. Fresh groundwater reserves were calculated and approved for each site in the amount of 499 m3/day for category B.

Remote Triggering of Damage Followed by Healing Recorded in Groundwater Pressure

Water levels in three adjacent water wells in the Yarmouk Gorge area have all responded to the 2020 Elazığ Mw 6.8 teleseismic earthquake. Water levels in two aquifers exhibited reciprocal behavior: during the first eight days after the earthquake, water level decreased by 40 cm in the deeper highly confined aquifer, and increased by 90 cm in the shallower less confined aquifer. The recovery of the water levels in both aquifers continued for at least three months. We interpret these observations as reflecting the increase in damage along the fault at the Yarmouk Gorge. Ground shaking increased the damage and permeability of this fault, temporarily connecting the two aquifers, allowing flow from the deep aquifer to the shallow one. Model results showing decreased permeability suggest that the fault healed by one order of magnitude within three days. This is the first documentation of decrease in permeability in a fault zone within such short time scales.

Reduction of Energy Consumption for Water Wells Rehabilitation. Technology Optimization

Groundwater wells are widely used in the energy sector, including for drinking water supplies and as water source wells in the oil and gas industry to increase production of natural gas and petroleum. Water well clogging, which can happen to any well for various reasons, is a serious problem that can lead to increased power costs due to a higher head to the pump, a reduction in the flow rate and various drawdown issues. If rehabilitation procedures do not take place in time, this can result in permanent loss of the well, and a new well must be drilled, which is not a sustainable approach. Rehabilitation methods for water wells usually include mechanical and chemical treatments, and even though these methods are well established and have been used for many years we can still observe many abandoned wells which could be rehabilitated. In this study, sets of cavitation generators are developed and used in combination with common conic hydrodynamic nozzles. This combination reduces the pressure in the system and makes the cleaning setup much lighter and more mobile. The designed nozzles were successfully used in hydrodynamic cleaning of four water wells.

Evaluate the Distribution of Heavy Elements that Dissolved in Ground Water Using IDW in AL-Wafa City, Al-Ramadi,Iraq

Groundwater can be assessed by studying water wells. This study was conducted in Al-Wafa District, Anbar Governorate, Iraq. The water samples were collected from 24 different wells in the study area, in January 2021. A laboratory examination of the samples was conducted. Geographical information systems technique was relied on to determine the values of polluting elements in the wells. The chemical elements that were measured were [cadmium, lead, cobalt and chromium]. The output of this research were planned to be spatial maps that show the distribution of the elements with respect to their concentrations. The results show a variation in the heavy elements concentrations at the studied area groundwater. The samples show different values of concentrations; for Cadmium (0.218-1.624) ppm, Lead (0.217-1.157) ppm, Cobalt (0.014-0156) ppm, and for Chromium (0.045-0263) ppm. The distribution of the materials concentrations differs for each element which is refer to the sources of pollution are not relate to industry, but it could be relate to fertilization.

Changes in paleo-underground water levels revealed by water wells and their relationship with climate variations in imperial China

Based on the records of the bottom elevations of 482 ancient water wells collected from published archaeological reports, we reconstructed the paleo-underground water levels (PUWL) in the urban areas of Chengdu, Changsha, Nanjing, Suzhou, Suqian, and Yancheng cities in the vicinity of 30° N in China. The PUWL fluctuations varied between the inland and the coastal regions and their transitional areas. There were four PUWL phases in the inland areas: low in Han (206 B.C.–A.D. 220), high in Tang (A.D. 618–907), low in Song (A.D. 960–1279), and high in Ming (A.D. 1368–1644). In contrast, there were five PUWL phases in the coastal regions: high in Han (206 B.C.–A.D. 220), low in Jin-Northern & Southern Dynasties (A.D. 266–589), high in Tang-Song (A.D. 618–1279), low in Ming (A.D. 1368–1644), and high in Qing-Republic of China (A.D. 1644–1949). Yet, there were no apparent changes in PUWL in the transitional areas between the inland and the coastal regions. Regional hydrological factors cause the geographic variations of the PUWL fluctuations. Precipitation changes drove the rise and fall of PUWL in the inland areas. In contrast, the variations of PUWL in the coastal regions were attributed to the temperature-induced sea-level changes. This study illustrates the potential of using PUWL in tracing paleo-environment changes and their driving factors, which is a novel approach in environmental archaeology.

A hydrogeochemical approach to the characterization of low-enthalpy geothermal systems: the Scordia – Lentini graben (Sicily, Italy)

We describe the geochemical characteristics of groundwater samples collected in 23 water wells located on the northern margin of the Hyblean plateau (East Sicily). This area, mostly made of highly permeable carbonate rocks, is rich in low temperature (T < 50° C) hydrothermal groundwaters, distributed in an active sismogenetic zone, with several ENE-WSW-directed tectonic structures that drove magma to the surface during Upper Pliocene and Pleistocene. The chemical features suggest complex mixing between rainwater, CO2-rich groundwater, steam-heated groundwater and geothermal brines, as highlighted by Principal Component Analysis (PCA). Some parameters, however, indicate widespread pollution of the aquifers from human activities. Stable isotopes analysis confirms the meteoric origin of groundwater and supports the origin of dissolved CO2 mostly from mantle degassing through deep tectonic faults. Geothermometric estimates, mostly based on quartz and Saturation Indexes geothermometers, suggest minimum reservoir temperature between 100 and 120° C.

Comparison and adaptability evaluation of formation pressure calculation methods and computer simulation in Jingbian gas field

In the process of oilfield development, formation pressure is an essential parameter for evaluating oilfield development effect, calculating dynamic geological reserves, conducting daily dynamic analysis of oil and water Wells and predicting oilfield performance. The pressure recovery time of conventional gas well after shut-in is very long, and it is difficult to effectively carry out targeted implementation due to the influence of gas field external supply task. In this paper, based on the actual data of Jingbian gas field, through the comparison of several calculation methods of formation pressure, the best method to calculate formation pressure is comprehensively screened out. The results show that: ①For a single method, the accuracy of the method from high to low is the well head casing pressure conversion method, the pressure drop curve method, the binomial productivity equation method, and the quasi-steady state mathematical model method.②The absolute error of multi-method comprehensive calculation method is 0.9MPa, which is far less than the average absolute error directly calculated by one method. The multi-method comprehensive calculation method is reliable when applied to the formation pressure evaluation of typical gas Wells in Jingbian gas field, which lacks data.