Journal of Earth Sciences and Technology

The fractured Tertiary volcanic aquifer in the Al-Sahoul Basin near Ibb City, Yemen, was systematically investigated to assess groundwater quality and the impact of anthropogenic activities on this critical water resource. Sixteen groundwater samples were collected from 26 boreholes and analyzed for key physicochemical parameters, including electrical conductivity (EC), pH, total dissolved solids (TDS), total hardness, total alkalinity (TA), bicarbonate (HCO??), carbonate (CO?²?), chloride (Cl?), sulfate (SO?²?), fluoride (F?), calcium (Ca²?), magnesium (Mg²?), sodium (Na?), and potassium (K?). Advanced tools such as Geographical Information Systems (GIS) and Surfer software were employed to generate geological, hydrological, and topographical maps for data visualization and interpretation. The results revealed that wells located in the western part of the basin exhibited significant contamination, with chemical concentrations exceeding Yemeni and World Health Organization (WHO) drinking water standards. This contamination is attributed to the proximity of a landfill on the western side of the basin, likely releasing leachates that degrade the water quality and render it unsuitable for drinking. In contrast, wells in the southern and eastern parts of the basin demonstrated better water quality, meeting the required standards for drinking and agricultural use. The study highlights the vulnerability of groundwater in the Al-Sahoul Basin to anthropogenic influences, particularly improper waste disposal. It emphasizes the urgent need for effective landfill management, regular monitoring of groundwater quality, and the implementation of mitigation strategies to safeguard this vital aquifer system. The findings provide critical insights for decision-makers, encouraging the development of sustainable water resource management policies to ensure safe and reliable access to water for the region’s population and agricultural needs. This research underscores the importance of proactive measures to prevent contamination and protect groundwater resources.

The effective prevention of hydrate formation and ensuring safe and efficient production of deepwater oil and gas resources are technical challenges in the petroleum industry. Combination of thermodynamic inhibitors has been proposed to improve the inhibition of hydrate formation and has received significant research attention. However, much has not been done to investigate the synergistic effect of hydrates inhibitors. In this work, the effectiveness of methanol and combination with calcium chloride (CaCl₂) on hydrate formation were analyzed. A simulation based method was applied to each volume section of the Pipeline/Riser system and a phase behavior and fluid property program was used to generate input file required by the simulation model. Sensitivity analysis was done for different percentage of inhibitor moles required to suppress hydrate formation for methanol injection and the co-injection of methanol with CaCl₂. The result shows that the fluid temperature was above the hydrate formation temperature up to a length of about 9660.54m along the pipeline/riser system and hydrate volume fraction which grows to a maximum value of 0.0000554089 at 12952.7m for the uninhibited system. For the injection of 10mol%, 20mol%, 30mol%, 40mol%, and 50mol% methanol, the hydrate volume fraction grows to a maximum value of 0.0000589137, 0.0000664168, 0.0000422186, 0.0000145381, and 0.000000440159 at 12952.7m, 12952.7m, 13448.5m, 13715.1m, and 13893.4m respectively. Methanol concentration of 60mol% was the optimum concentration required for hydrate prevention. For the co-injection of methanol and CaCl₂, 40mol% methanol and 20mol% CaCl₂ was required for hydrate prevention. The co-injection of methanol and CaCl₂ results in the reduction of the quantity of methanol required for hydrate prevention by 20%. The co-injection of alcohol and electrolytes should be deployed to reduce the significant quantities of alcohol required for hydrate suppression. 

In this study, we analyzed a thorough examination of seismic hazard assessment for Karachi city, with the aim of ensuring the construction of safe and sustainable buildings and structures. Karachi, being the largest city and an economic hub of Pakistan, serves as the focal point for this study. The study begins by assessing the potential danger posed by an earthquake resulting from tectonic activity in the area. To accomplish this, the region, which spans approximately a radius of 200 km, is divided into eight distinct seismic zones. The study incorporates ground motion prediction equations that are compatible with the seismotectonic environment of the study area. The resulting ground motions are determined by the peak horizontal ground acceleration and the 5% damped spectral acceleration (SA). The seismic activity in the study area is primarily characterized by small to moderate earthquakes, as indicated by recorded data. Based on the historical earthquake data, it has been observed that significant earthquakes with high magnitudes have taken place within a radius of approximately 200 km from Karachi, such as the Bhuj earthquake in 2001. The primary active tectonic features in the region include the Pab Fault, Kirthat Fault, Hab Fault, Jhimpir Fault, Surjan Fault, Ornach-Nal Fault, and Rann of Kutch Faults. In order to ensure the safe and sustainable seismic design of building structures in Karachi, it is advised to adhere to the recommended seismic design parameters. These parameters include a peak ground acceleration (PGA) of 0.19g and 0.33g, with a shear wave velocity (Vs30) of 750m/sec for foundation conditions. The return period for these parameters is determined based on the nature of the structures, with a value of 475 years for one set of parameters and 2,475 years for the other.

Water is an important resource in a variety of economic activities, from agriculture to industry. Due to its intrinsic properties, ground water has become a highly important source of water supplies in all climatic zones of Pakistan. The results of GIS-based analytical methodologies used for groundwater potential zonation in Punjab, Pakistan, are presented in this study. The goal of this research is to find areas with shallow groundwater potential. In ArcGIS software, the investigation is carried out utilizing the weighted overlay approach, fuzzy logic, and AHP analysis tools. Land use, slope, geology, geomorphology, distance to water bodies, permeability, soil, faults, drainage density, and rainfall were chosen as input layers for this study because these parameters all have an impact on groundwater to varying degrees. These input map layers were first georeferenced with UTM Zone N43, datum WGS 1984, and translated to raster form, after which they were classified according to their expected significance in groundwater zonation using the weighted overlay approach. As weighted overlay methodology is biased towards prioritizing layers, the other two studies were then used to check for chronology in the maps that had been examined and to find out the most reliable model. The maps created from the three approaches were validated through the groundwater data collected for different regions of Punjab. The AHP analysis method turned out to be the most suitable one and matched the validation map more precisely, which concluded that 3% of the regions lie in very shallow zones, 38% in shallow zones, 27% in moderate zones, 14% in deep zones, and 18% in very deep zones. Finally, the study identifies the most advantageous places in Punjab where groundwater can be found at specified depths. This information on groundwater potential will be important in identifying ideal places for water extraction and the installation of recharge wells.

Completion types and tubing sizes have been identified to play a major role in achieving an optimum production rate while utilizing the reservoir energy optimally. Adequate completion helps in optimizing production while minimizing pressure drop and predicting the longest flowing time. In this work, the effect of well completion configuration and tubing sizes on well performance was evaluated with a steady state simulator (PIPESIM®). A wellbore model was built and completed with both casing and liner completions with flow through the tubing and annulus.  Sensitivity analysis was run for different tubing sizes for a given completion type and flow configuration on the well performance. Results showed that increase in tubing sizes from 2.441 inches to 2.992 inches for cased hole completion yielded 22.28% increase in production rate and 22.26% increase in production rate when the tubing sizes was increased from 2.441 inches to 2.992 inches for liner completion for tubing flow respectively. For tubing and annular flow, production increased from 4867.531STB/day to 4875.321STB/day for tubing sizes of 4.5 inches to 4.9 inches for liner completion and the same production rate of 4872.075STB/day with tubing sizes of 4.5 inches to 4.9 inches for open hole completion. This work has shown that changing the tubing sizes for optimization should only be considered for cased hole and liner completions with tubing flow configuration because both casing and liner completion methods with tubing and annular flow gave almost the same results as the tubing sizes were changed. Therefore, completion type with tubing sizes should be examined during design of a well to enhance productivity.

Electrical resistivity and ground magnetic methods are widely used for identification of groundwater potential zones and in delineating the lateral and vertical distribution of sub-surface. Electrical resistivity technique can also differentiate the ingress of sea water into inlands thereby getting mixed up with fresh water bodies. The present studies are an attempt to delineate the saline water-fresh water interface and to demarcate the faults and lineaments in parts of Kudal-Vengurla and surrounding coastal region of western Maharashtra. A total of 30 vertical electrical soundings were carried out using the Schlumberger configuration with AB/2= 100m. The IPI2WIN algorithm based on automatic as well as manual interpretation of electrical sounding curves was used for analyzing the resistivity data set. The pseudo cross-sections of resistivity data over five profiles in the study region show the flow of saline water from the coastal side, partly controlled by the lineaments. A total of 122 ground magnetic data points were also acquired from the study region and the analysis was performed using SURFER software. From the observed magnetic anomaly map it appears that NW-SE trend are parallel to the present day coast line and can be associated with the coastal tectonics. The structural elements and magnetic sources within and below the trap covered region are delineated.