Journal of Earth Sciences and Technology

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.

Carbon dioxide, CO2 sequestration is a feasible solution to reduce the amount of CO2 in the Earth’s atmosphere. However, constant monitoring of the CO2 effect after the injection is important to ensure safe and prolonged storage of the CO2 in the geological site. This study is about the feasibility study of CO2 sequestration in a depleted carbonate reservoir in Central Luconia, Sarawak, Malaysia using rock physics and seismic forward modeling. Two well log datasets from Central Luconia are used in this study. Hampson-Russell Software and Microsoft Excel are utilized to obtain the results. In this paper, Gassmann Fluid Substitution Model is used to study the elastic properties change in the depleted carbonate reservoir due to the injection of CO2. 1D seismic forward modeling is generated from the P-wave velocity, S-wave velocity and density acquired for the different case scenarios to study the effect of CO2 towards the seismic response. Post-Stack and Pre-Stack seismic attributes are generated to determine the most sensitive seismic attributes for identifying CO2 injection effects through qualitative and quantitative analysis. Elastic properties such as P-Impedance, Vp/Vs ratio, Lambda-Rho, Mu-Rho, SQp and SQs are calculated. A number of elastic properties cross plots are generated to select the best elastic properties for CO2 monitoring. Based on the findings, the feasibility study of CO2 sequestration in Central Luconia depleted carbonate reservoir using rock physics and seismic forward modeling is proven to be viable.

Although, the rainfall and scarcity of rainfall is critically important issue for the Purulia; but the analysis of rainfall is far from the proper conclusive statement till date. In this research, an attempt has been made to analyze the annual and seasonal rainfall trends along with the change point of annual rainfall in the Purulia District for 35 years (1979 to 2013) using the monthly rainfall data of seven meteorological stations. The Mann-Kendall test was used to identify the trend in rainfall data and Theil-Sen’s slope estimator was utilized to assess the magnitude of trend. Trend-free pre-whitening method was used to eliminate the influence of significant lag-1 correlation from the series. Change in magnitude was derived in terms of percentage change over mean rainfall. The Pettitt and Lanzante test had been used in the annual rainfall series to identify the most probable change point for the series of annual rainfall. After analysis, a significant trend was found at one station in annual rainfall. The seventh, fifth and third stations were identified with the highest positive change in magnitude for the annual, pre-monsoon, monsoon and post-monsoon series respectively. The highest negative change was portrayed in the first station during the Winter phase. The most probable change point was identified at 1987-1988 for all meteorological stations. In the pre-change point phase, the highest positive change was found in the southern sections and the lowest positive change was marked in the northern portions of the study area. In contrary, completely a reversed scenario was marked in the post change point phase. Therefore, it can be concluded that the tendency of rainfall was shifted in the northern portions after the change point. The findings presented in this research can be a helpful tool for the planners to strategize local level agricultural planning of the Purulia District.