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Lahore is the provincial capital of Punjab and the second most populous city in Pakistan. Aquifer rechargerates have been continuously decreasing over a long period of time, which has caused a significant decline in the watertable level. Rapid population growth, urban development, and industrialization have all raised the demand for watersupplies. Due to significant infrastructural development, a considerable portion of the land is now impervious andrainfall now drains as surface runoff rather than recharging the aquifer level. Average annual rainfall, one of theprimary sources used to replenish the Lahore aquifer, is insufficient to prevent the depletion of the water table, andRiver Ravi stays almost dry except in rainy seasons. Geographic information system (GIS) and remote sensing (RS)techniques are used to find suitable areas for replenishment in the Lahore aquifer system in order to enhancesustainability and prevent decreasing groundwater levels. Distance from the water channel, land use/land cover(LULC), slope, geology, drainage density, rainfall, lineament density, and soil type are the eight layers that have beenintegrated with the GIS overlay analysis. Thematic maps are generated using both conventional and remote sensingdata. These maps are eventually converted to raster data. Very good, good, moderate, poor, and very poor are the fivezones that have been delineated. A good to very good

The Cretaceous shale intervals of Talhar and Sembar Formations – distributed in the Lower Indus Basin of Pakistan – are organic-rich shales that can act as shale gas plays. Two-dimensional seismic using synthetic modeling has been carried out in Khewari oil field to identify petroleum plays. This work was completed with the help of eight seismic processed and migrated lines. Based on structural interpretation different geological structures were marked. The seismic character, continuity, and coherency in seismic reflection patterns indicate that the area is under an extensional regime with normal faults pattern associated with horst and graben structure. This structure is favorable for the accumulation of hydrocarbon. The shales of Talhar and Sembar formations are overlying Chilton limestone, which is a proven reservoir. The isopach maps show that Talhar Shales and Sembar Formation are dipping towards the northeast. Precisely to characterize the reflector, a synthetic seismogram was employed to tie well tops and seismic profiles.

Peak ground acceleration is the maximum ground shaking intensity parameter in geophysics. To prevent the big loss of infrastructure, dam site or multistorey buildings as well as power project due to any seismic hazard, it is essential to mitigate the damages. Seismic hazard analysis for peak ground acceleration was carried out for hydropower project in Gilgit Baltistan to mitigate the effect of seismic hazard. Seismicity and tectonic map was drawn for distribution of seismic events.Study region was divided into seven source zones to rectify the seismic risk reduction assessmement of the region. Regression analysis for freqeuncy magnitude was also carried out using seismicity catalogue. Three distinct ground motion equations were used to predict the value of g with their return period. The actitvity rate analysis of seismic source zones was also done drawn to determine the source contribution. Maximum credible earhquake, operational based earthquake and maximum design earthquake were detremined. According to the ICOLD and seismic risk reduction policy, the values of peak ground acceleration for Phandar hydro power project was 0.59g for maximum credible earthquake, for design basis earthquake g value was 0.311g for and 0.231g foroperational basis earthquake with 475 years of return period at 50% probability of exceedence. Spectral acceleration for 0.1s, 0.2s, 0.5s, 1s and 2s was also computed for horizontal and vertical components. The values of spectral accleeration varied from 0.19g to 1.250g for maximum credible earthquake, 0.019g to 0.700g for design based earthquake and 0.050g to 0.480g for operational based earthquake. The results reveal that the maximum credible earthquake is to ensure safety level and for reliability level, operational based and design based earthquakes can be utilized.

The use of rock physics modeling and petrophysical analysis has become an integral part of quantitative seismic interpretation. In the present study, the above-mentioned techniques are applied to the reservoir interval of Basal Sand of Cretaceous age widely distributed in the Lower Indus Basin of Pakistan. The data used for this purpose consists of complete suits of wireline logs from four well A, B, C and D. The primary goal of this work is to understand the trends of seismic parameters such as P-wave velocity (VP), S-wave velocity (VS), bulk modulus, bulk density as a function of fluid saturation and porosity in this sand interval. Petrophysical analysis based on well logs is used to obtain petrophysical properties such as porosity, the volume of shale, fluid saturation, P-wave velocity (VP), S-wave velocity (VS) and density at reservoir conditions. The results show that seismic parameters are very sensitive to fluid saturation, fluid types and rock-forming sediments. Reservoir porosity and fluid saturation control the elastic response of Basal Sand due to which seismic velocities decrease with an increase in porosity and fluid saturation.

The proposed site of the Diamer Bhasha Dam in northern Pakistan is situated in an active tectonic zone with intensive seismicity, which makes it necessary for seismic hazard analysis (SHA). Deterministic and probabilistic approaches have been used for SHA of the dam site. The Main Mantle Thrust (MMT), Main Karakaram Thrust (MKT), Raikot-Sassi Fault (RKSF) and Kohistan Fault (KF) have been considered as major seismic sources, all of which can create maximum ground shaking with maximum potential earthquake (MPE). Deterministically estimated MPE for magnitudes of 7.8, 7.7, 7.6, and 7.1 can be produced from MMT, MKT, RKSF and KF, respectively. The corresponding peak ground accelerations (PGA) of 0.07, 0.11, 0.13 and 0.05 g can also be generated from these earthquakes, respectively. The deterministic analysis predicts a so-called floating earthquake as a MPE of magnitude = 7.1 as close as 10 km away from the site. The corresponding PGA was computed as 0.38 g for a maximum design earthquake at the project site. However, the probabilistic analysis revealed that the PGA with 50% probability of exceedance in 100 years is 0.18 g. Thus, this PGA value related to the operational basis earthquake (OBE) is suggested for the design of this project with shear wave velocity (Vs30) equal to 760 m/s under dense soil and soft rock conditions.

The groundwater potential zone (GWPZ) mapping is fundamental target in urbanization and socio-economic development as well as environmental protection of an area. The delineation of fresh groundwater and saline water boundaries is a very crucial in water scarcity areas. Conventionally, geophysical survey is conducted for this objective, which is expensive and time consuming. Islamabad, the capital city of Pakistan – a part of the Potwar Plateau – belongs to water scare area where sustainable supply of fresh water is very challenging. Remote Sensing (RS)/GIS techniques are applied for GWPZ in the study area comprised of 6,000 km2. Geology, land use/ land cover (LULC), slope, lineament density, geomorphology, rainfall, drainage density, soil type thematic maps were prepared using geological information, rainfall data and Shuttle Radar Topographic Mission Digital Elevation Model (SRTM DEM). The analytical hierarchical process (AHP) multi-decision making analysis indicate that the weights of multiple parameters influence the GWPZ vary from 0.36 – 0.02 with LULC receives maximum weightage and soil type with minimum weightage. Based on these thematic maps GWPZ map was prepared and the whole area under investigation was classified into five groundwater potential zones ranging from very poor to very good. The study reveals about 50 % of the entire total surface territory having good to very good potential for groundwater prospecting and around 20 % area falls in poor to very poor zone. Due to the distribution of surficial, stream deposits and agricultural area with water penetration capacity, the very good GWPZ are dominating in the south and northwestern areas in the research region.

The groundwater potential zone (GWPZ) mapping is fundamental target in urbanization and socio-economic development as well as environmental protection of an area. The delineation of fresh groundwater and saline water boundaries is a very crucial in water scarcity areas. Conventionally, geophysical survey is conducted for this objective, which is expensive and time consuming. Islamabad, the capital city of Pakistan – a part of the Potwar Plateau – belongs to water scare area where sustainable supply of fresh water is very challenging. Remote Sensing (RS)/GIS techniques are applied for GWPZ in the study area comprised of 6,000 km2. Geology, land use/ land cover (LULC), slope, lineament density, geomorphology, rainfall, drainage density, soil type thematic maps were prepared using geological information, rainfall data and Shuttle Radar Topographic Mission Digital Elevation Model (SRTM DEM). The analytical hierarchical process (AHP) multi-decision making analysis indicate that the weights of multiple parameters influence the GWPZ vary from 0.36–0.02 with LULC receives maximum weightage and soil type with minimum weightage. Based on these thematic maps GWPZ map was prepared and the whole area under investigation was classified into five groundwater potential zones ranging from very poor to very good. The study reveals about 50% of the entire total surface territory having good to very good potential for groundwater prospecting and around 20% area falls in poor to very poor zone. Due to the distribution of surficial, stream deposits and agricultural area with water penetration capacity, the very good GWPZ are dominating in the south and northwestern areas in the research region.

The organic-rich shale intervals of Patala Formation of Paleocene age may be considered as potential shale gas play in the Upper Indus Basin of Pakistan. Until now, seismic and elastic properties of the Patala shales are not investigated in detail necessary to declare it as shale gas play and to differentiate shale gas pay zone from the non-pay zone. Data of eight wells in which Patala shales were encountered at various depth levels from 2000 to 4300 m were deeply investigated for shale gas characterization. This shale fulfills the basic criteria of organic-rich shale with TOC ~ 0.5–5.8%, vitrinite reflectance (level of maturity) is 0.6–1.7%, average thickness 48 m. The brittleness index (BI) of this organic-rich shale was computed by using effective mechanical properties and mineralogy to define brittle zones in the shale intervals preferable for generating the fracture network. BI data points demonstrate that a large number of values fall in the brittle zone, whereas fewer values fall in the ductile zone. However, a certain number of values fall in the brittle–ductile transition zone. The quantitative comparison between different elastic and seismic properties derived from the wireline logs guide for the delineation of the pay zone from the non-pay zone in the organic-rich shale intervals.

Corrosion of subsurface steel structures is very critical issue especially in moisture subsoil. The use of physiochemical properties such as pH, salts concentration, electrical resistivity is very common to quantify corrosive nature of subsoil. However, the laboratory measurements of these parameters are quite difficult due to time and budget constraints. In this work soil corrosion potential of a power plant site was evaluated using geophysical and geotechnical investigations. Soil samples were collected from 15 boreholes drilled up-to 50 m depth for laboratory testing whereas 3 probes of four electrodes vertical electrical sounding (VES) using Wenner configuration were also performed to measure the electrical resistivity of the subsurface soil up to 50 m depth. According to the USCS soil system silty clay (CL-ML) was interpreted as dominant material in all boreholes as shallow depth. Poorly graded sand (SP) including silt (SM) was found of variable depth in almost each borehole. The true resistivity values at the depth of 30 meters lies between the 19.9 ohm- meters to 59.8-ohm meters. All observation points of electrical resistivity survey VES-I, VES-II and VES-III near-surface material show moderate soil corrosion potential which is favorable for design of earthing. Up to depth of 4 m, the values of resistivity 52.6 to 59.8 ohm-meters shows adequate estimation of corrosion. According to the International standard these curves belong to bell type or K type curve of resistivity model. Their resistivity values with respect to depth show low to moderate corrosion potential which is satisfactory for construction at this depth after applying the nominal cathodic protections. Thus, electric pipe lines may be installed at this depth.

The reservoir character of Cretaceous prolific clastic rocks, widely distributed in different sedimentary basins of Pakistan, is poorly established due to its heterogeneous behavior. In this study, electrofacies classification, principal component analysis, cluster analysis, and petrophysical analysis were performed to establish reservoir character of the Lumshiwal Formation. The electrofacies analysis reveals that the Lumshiwal Formation contains: clean sands with blocky log behavior, shaly sands with intercalated shale beds, sandy shales, and shale. Petrophysical analysis was accomplished by using standard practices with the help of wireline logs of fifteen wells drilled in the study area. After wireline logs and core sample calibration, the Lumshiwal Formation was divided into A, B, and C zones with an effective porosity 5–32% in zone A, 12–17% in zone B, and 13–27% in zone C with high permeability and very low volume of shale. The results revealed that Lumshiwal Formation represents relatively a vertically and laterally heterogeneous sedimentary unit with good quality reservoir facies, which were deposited in shallow marine environment with upward coarsening grain size.

Reservoir geomechanics is essential for cost-effective drilling in complex areas, reducing risks related to wellbore stability problems, and other issues related to abnormal pore pressure, efficient reservoir modeling and enhanced oil recovery (EOR) plans. The information of major sources of overpressure generation like tectonics, under compaction, hydrocarbon accumulation and presence of an effective seal is necessary to apply reservoir geomechanics. The present study comprises of structural interpretation and comparative petrophysical evaluation of the Chorgali Formation with special emphasis on reservoir geomechanics for this Eocene reservoir in an oil field. This field is in the Potwar Plateau, included in the list of areas of the world containing over-pressured sedimentary rock. The main objective of this research work is to determine the pore pressure using well log data for two wells. In this model sonic transit (DT) time is correlated to recognize the compaction history for more accurate pore pressure prediction and to analyze the dependence of compressional wave velocity on vertical effective stress, stiffness of material and pore pressure. Pore pressure prediction by using well log data is much more affordable and gives continuous and extensive range of data than direct measurement by modular dynamic tester, drill stem test and repeat formation tester, etc. One dimensional (1D) well concentric mechanical earth model (MEM) is developed for reservoir geomechanics of Eocene carbonates. Seismic interpretation results reveal thrusting and popup structures in the area due to compressional tectonic regime. Petrophysical analysis discloses that the Chorgali Formation has better reservoir characteristics as compared to the Sakesar Formation. Compaction disequilibrium in argillaceous layers and hydrocarbon accumulation in reservoir zones are primary sources of overpressure. The well log-based pore pressure estimation shows good agreement with the in-situ measured formation pressure obtained from modular dynamic tester (MDT). The variation in rock physics properties such as bulk modulus, Young's modulus, shear modulus and Poisson's ratio are also modeled to delineate the high pore pressure zones. Reservoir geomechanics results illustrate that the predicted abnormal pore pressure is mainly due to significant hydrocarbon potential in the Chorgali Formation. On the other hand, shales deposited in the Sakesar Formation during Early Eocene are over-pressured due to compaction disequilibrium.

The study area lies in Southwestern part of Sahiwal District, Punjab, Pakistan, which is the central part of interfluves system, i.e., Bari Doab. Hydrogeophysical investigations were carried out for the spatial appraisal of groundwater aquifers resources in the study area through electrical resistivity survey. A total of forty vertical electrical soundings through Schlumberger electrode configuration are conducted in the study area. The interpreted results of electrical resistivity survey along with interactive modeling suggest that four to six numbers of geo-electric layers exist in the subsurface in the study area. The alternating alluvium comprised of silt, sand, gravel, and kanker layers has been interpreted. The interpreted resistivities are categorized from very high to very low in the study area. Below the water table, very low resistivity values interpreted mainly as sand and sand-gravel saturated with saline water. Moreover, the interpretation of our developed maps also leads to demarcate the fresh and saline groundwater zones. Interpreted results decipher that this gigantic saline water zone starts below the depth of 150 m and extends below the depth of 300 m. The models of true resistivities are also calibrated with the lithological logs of test holes and tube wells within the study area. The sandy and gravel layers are the most promising zones for good-quality groundwater that leads to the development tube wells up to the depth of 150 m within the study area.

Unconventional energy resources such as shale gas are becoming an increasingly important exploration and production targets. Organic-rich shales are widely distributed in the sedimentary basins of Pakistan. Among these shales, organic-rich Sembar shale of the lower Cretaceous age is a strong potential shale gas play in the lower Indus basin of Pakistan. However, seismic and petrophysical characterization of this organic-rich shale is not well understood because of the complex dependency of the seismic and petrophysical properties of these rocks on mineralogical, heterogeneities, organic matter, clay content and thermal maturity. Therefore, to understand the seismic and elastic character of Sembar shales, rock physics modeling and seismic attribute analysis have been done. The results reveal that in-situ mineral composition, total organic content (TOC) and thermal maturity can influence significantly in inverse order to the seismic and elastic parameters of organic-rich shale. This work will facilitate the workers to interpret shale gas play and develop the exploration and production strategies for gas exploration and production.

Spreadsheet-based programming has become a worldwide computational tool and a powerful platform for executing scientific calculations in different engineering disciplines. The inherent advantage of spreadsheets exists in integrated storage and the ability to manipulate matrices along with wide-ranging mathematical calculations, plotting, and diagrammatic presentation. This paper presents a user-friendly and interactive spreadsheet program “AVA-anisotropy” to characterize the primary P-wave amplitude versus incident angle (AVA) responses in vertically transverse isotropic (VTI), horizontally transverse isotropic (HTI), and orthorhombic media. The set of Ruger’s equations for isotropic, VTI, HTI, and orthorhombic media are solved to describe the seismic energy partitioning at an anisotropic interface. The spreadsheet program has three main sections: basic concepts, data input, and AVA modeling for anisotropic media. The interactive data input and on-screen mathematical and graphic presentation of the spreadsheet enables the students to have an in-depth examination of the effects of changing input data and the resulting model. This greatly helps them in understanding the energy partitioning in anisotropic medium.

The proper understanding of earthquake geometry and location is very important to understand the seismicity of an area. In the present study, 185 earthquakes that occurred in the northwest Himalaya of magnitude Mw > 0.6 between 2010 and 2013 were relocated using the Modified Joint Hypocenter Determination method. After examining seven velocity models, average VP/VS ~ 1.73 computed by Wadati diagram is used to improve the hypocenter locations of the earthquakes. Based on hypocentral distributions, these earthquakes were classified into four groups. Group 1 is along the Punjal Thrust in Hazara Kashmir Syntaxes. Group 2 belongs to the Indus-Kohistan Seismic Zone whereas group 3 is along the Besham dome and the fourth group is along the Main Mantle Thrust. Shallow crustal earthquakes were relocated to 0–50 km, deep earthquakes were relocated to 50–100 km, and much deep earthquakes were relocated to 250–350 km depth. This analysis will be helpful to understand the seismicity of the northwest Himalaya of Pakistan.

In the above published article in October 2018 issue of the Journal of the Geological Society of India (v.92, pp.465–470).

Petrophysical evaluation and rock physics analysis are the important tools to relate the reservoir properties like porosity, permeability, pore fluids with seismic parameters. Nevertheless, the uncertainties always exist in the quantification of elastic and seismic parameters estimated through wireline logs and rock physics analysis. A workflow based on statistical relationships of rock physics and logs derived elastic and seismic parameters with porosity and the percentage error exist between them is given. The statistical linear regressions are developed for early Eocene Chorgali Formation between various petrophysically factors determined from borehole logging of well Ratana–03 drilled in tectonically disturbed zone and the seismic and elastic parameters estimated through rock physics modeling. The rock physics constraints such as seismic velocities, effective density and elastic moduli calculated from Gassmann fluid substation analysis are in harmony and close agreement to those estimated from borehole logs. The percentage errors between well logs and rock physics computed saturated bulk modulus (K sat ), effective density (ρ eff ), compressional and shear wave velocities (V P and V S) are 1.31%, 4.23 %, 5.25% and 4.01% respectively. The permeability of reservoir intervals show fairly strong linear relationship with the porosity, indicating that the reservoir interval of the Chorgali Formation is permeable and porous thus having large potential of hydrocarbon accumulation and production.

Turbidite-embedded lowstand prograding wedges are hot topics in the sequence stratigraphic consortium. The lowstand prograding wedges within the lowstand system tract are mud-prone in deep-water settings, and hence, sandstone reservoirs become ultra-thin to be detected using bandlimited seismic. The prediction of thin-bedded (hydrocarbon-charged) lowstand prograding wedge reservoirs along the structural closure is therefore a challenge. We delineate thick and porous source and reservoir segments by interpreting the seismic stratigraphy and performing continuous wavelet transforms of spectral decomposition tools on the Indus Offshore, Pakistan. The 48 Hz resolves the shallow-marine coarse-grained hydrocarbon-bearing oblique-tangential clinoforms, faults, source rock, and shale out zone, which captured the lowstand prograding wedges play. The 48 Hz images the lowstand prograding wedge geomorphology and high-energy coarse-grained turbidity channelized basin floor fans source beds. The bandlimited seismic facies simulation predicted a 15 to 25 % porosity and a thickness of 5.7 m for porous oblique-tangential prograding clinoform facies. The CWT-based spectral seismic facies and porosity simulations predicted a 15 to 35 % porosity and enhanced reservoir thickness of 11 m for oblique-tangential prograding clinoform facies, which suggested robust indicators for explorations of lowstand prograding wedge plays in the Indus Offshore and other similar basins.

This study describes a method of combining geostatistical analysis with geophysical inversion of 1D electrical resistivity data acquired in the Bannu Basin, northwestern Himalayas of Pakistan. The data has been integrated and broadened from single dimension resistivity data into a 2D model that can be fully visualized and interpreted in a spatial sense. By interpreting and calibrating the electrical resistivity curves with the lithologies and geophysical logs of boreholes, it has been possible to identify unique sedimentary accumulations that occur throughout the basin. Through the use of variogram modelling the spatial extent of these accumulations can be identified and associated with measured hydraulic properties. It has become possible to map the extents and facies of the alluvial systems of the Bannu Basin formed during periods of heightened tectonic activity. The coarser sediments are associated with higher levels of resistivity as measured in the electrical surveys, whereas the finer sediments exhibit characteristically lower resistivities. Thus, the zones of high and low resistivity values become indicative of sediments associated with alluvial fans and lacustrine environments, respectively. The sediments of alluvial fans show relatively low gamma ray levels and higher transmissivities, whereas those of the piedmont deposits as well as lacustrine and sandy plains tend to show medium to high gamma ray values and lower transmissivities. Gross transmissivities were estimated by studying regression relationships between transmissivities measured in boreholes and the apparent formation factors of sediments. These relationships indicate an exponential increase in transmissivity with increasing apparent formation factor. These trends suggest a contrast in transmissivities between alluvial fan and other environments where lacustrine and sandy plains are characterized by low transmissivities. These estimated transmissivities do not represent absolute values but are merely indicative of any high or low trends in transmissivity of sediments, throughout the basin.

The use of seismic direct hydrocarbon indicators is very common in exploration and reservoir development to minimise exploration risk and to optimise the location of production wells. DHIs can be enhanced using AVO methods to calculate seismic attributes that approximate relative elastic properties. In this study, we analyse the sensitivity to pore fluid changes of a range of elastic properties by combining rock physics studies and statistical techniques and determine which provide the best basis for DHIs. Gassmann fluid substitution is applied to the well log data and various elastic properties are evaluated by measuring the degree of separation that they achieve between gas sands and wet sands. The method has been applied successfully to well log data from proven reservoirs in three different siliciclastic environments of Cambrian, Jurassic, and Cretaceous ages. We have quantified the sensitivity of various elastic properties such as acoustic and extended elastic (EEI) impedances, elastic moduli (K sat and K sat–μ), lambda–mu–rho method (λρ and μρ), P-to-S-wave velocity ratio (V P/V S), and Poisson’s ratio (σ) at fully gas/water saturation scenarios. The results are strongly dependent on the local geological settings and our modeling demonstrates that for Cambrian and Cretaceous reservoirs, K sat–μ, EEI, V P/V S, and σ are more sensitive to pore fluids (gas/water). For the Jurassic reservoir, the sensitivity of all elastic and seismic properties to pore fluid reduces due to high overburden pressure and the resultant low porosity. Fluid indicators are evaluated using two metrics: a fluid indicator coefficient based on a Gaussian model and an overlap coefficient which makes no assumptions about a distribution model. This study will provide a potential way to identify gas sand zones in future exploration.

The lower Indus basin is one of the largest hydrocarbon producing sedimentary basins in Pakistan. It is characterized by the presence of many hydrocarbon-bearing fields including clastic and carbonates proven reservoirs from the Cretaceous to the Eocene age. This study has been carried out in the Sanghar oil field to evaluate the hydrocarbon prospects of basal sand zone of lower Goru Formation of Cretaceous by using complete suite of geophysical logs of different wells. The analytical formation evaluation by using petrophysical studies and neutron-density crossplots unveils that litho-facies mainly comprising of sandstone. The hydrocarbons potentialities of the formation zone have been characterized through various isoparameteric maps such as gross reservoir and net pay thickness, net-to-gross ratio, total and effective porosity, shaliness, and water and hydrocarbons saturation. The evaluated petrophysical studies show that the reservoir has net pay zone of thickness range 5 to 10 m, net-togross ratio range of 0.17 to 0.75, effective porosity range of 07 to 12 %, shaliness range of 27 to 40 % and hydrocarbon saturation range of 12 to 31 %. However, in the net pay zone hydrocarbon saturation reaches up to 95%. The isoparametric charts of petrophysically derived parameters reveal the aerial distribution of hydrocarbons accumulation in basal sand unit of the lower Goru Formation which may be helpful for further exploration.

The quantification and assessment of groundwater are of great significance for the urbanization and town planning in an area. The current study has been carried out for quantification and assessment of groundwater quality zones by using geo-electrical technique in Faisalabad area (73° 06′ 08″–73° 11′ 59″ E; 31° 35′ 00″–31° 40′ 39″ N) of Pakistan. Vertical electrical soundings (VES) at six locations were conducted by Schlumberger configuration up to 300-m depth of investigation. Modeling technique is used for the interpretation of apparent resistivity, and the true resistivities of various subsurface lithologies were recorded from 2.10 to 55 Ω m for the depth of investigation. Three sand-dominant aquifers were identified at depth intervals of 0–50 m, 50–100 m, and 100–300 m. The VES results are compared and calibrated with the available borehole data taken from the tube wells drilled in the vicinity of the study area. The GIS technique is applied for the preparation of water quality zonation maps. Some of the groundwater quantification parameters such as total volume of the alluvium, total volumes of the water content, and active storage are estimated through GIS applications. Top geo-electrical layer (0–50 m) is dominated by low resistivity zone (10–25 Ω m), having an active storage of 0.71 km3. Intermediate geo-electrical layer (50–100 m) comprised coarse sand with low-to-medium resistivity zone of 10–35 Ω m, showing a low active storage (1.01 km3). Deep geo-electrical layer (100–300 m) is dominant by very low resistivity zone (

This research deals with the sensitivity of the hypsometric integral (HI) and hypsometric analysis to map active sedimentation and tectonics in the southern Suleiman fold and thrust belt (SSFTB)—a part of extensive folds and thrusts system vastly distributed along the western margin of the Indo-Pakistan sub-plate. We used SRTM DEM with 90 m spatial resolution to determine HI values in the SSFTB in Pakistan. In order to estimate maximum, minimum, and mean elevations of the study area, grid of regular squares of different sizes was analyzed. The active erosional stages and topographic development using digital elevation model (DEM)-derived HI were analyzed. The Shuttle Radar Topography Mission (SRTM)-based DEM is employed to carry hypsometric investigation and isobase codings. For the tectonic geomorphological analysis, the HI and hypsometric curves (HCs) were used to decode the recent and active surface deformation and its influence on the local topography of SSFTB. Spatial autocorrelation is applied to compute the distribution of HIs to see the possible clustering, dispersion, or randomization. Spatial autocorrelation demonstrates that the HIs are auto-correlated because of higher positive values of Z-scores. The spatial statistical analyses indicate that the HI clusters and hot spot are spatially correlated with each other having high positive Z-scores. The study concluded that the central parts and north-north-eastern and north-north-western parts of the SSFTB show more hot spots as compared to south-eastern and south-western parts. The analysis reveals that the resolution of the hot spots depends largely on the grid size and its quality decreases with increase in grid size and vice versa. Hot spots corresponding to higher values of HI are steady with uplifting and active topography and reveal a strong connection with the different structures in the study area. Cold spots correspond to the shallow depth earthquakes and active sedimentation close to fault lines.

Breakthroughs in shale gas exploration and production technology in China point to a possible solution to Pakistan's current energy crises. In this study, we evaluate the shale gas prospects in the Kohat-Potwar Plateau of Pakistan by establishing an integrated approach involving the analysis of fundamental elastic and petrophysical properties, Rock-Eval pyrolysis, and the sealing mechanism of shale. Detailed geochemical and petrophysical evaluation of the Patala Formation in the Kohat-Potwar Plateau indicates the good potential for shale gas with the following characteristics similar to the Longmaxi shale of Sichuan Basin China, i.e., (i) complex structural types sandwiched by tight limestone strata with low porosity (less than 3%), ultra-low permeability, high density, and large thickness which provides strong sealing capacity for gas preservation and enrichment; (ii) multiphase tectonic evolution of Patala Formation allowed various slippage processes to develop fractures and enhance the porosity and permeability; (iii) high organic matter content and thermal maturation stage (TOC > 2%, 416–445 °C); (iv) high brittle minerals content (e.g., calcite and dolomite > 40%); and (v) large formation thickness (>30 m) at shallow burial depth

Porosity is one of the key factors of a reservoir system that is typically distributed in a spatially non-uniform and non-linear manner. Nevertheless, spatial distribution of porosity in stratigraphic traps (channel sand bodies) is challenging due to the variations in depositional environments, shale intercalation, and repetition of textural changes in the pore sizes. This paper presents a strategy of joint inversion that combines support vector machine (SVM) and particle swarm optimization (PSO) algorithms to predict the spatial distribution of porosity using well logs and seismic data. In addition, Gaussian simulation algorithms (sequential Gaussian and Gaussian indicator simulations) were used to predict lithology and porosity distribution using wireline logs and core data. Rock physics modeling was performed to bridge the gap between the elastic and petrophysical properties for seismic-inversion based reservoir characterization. The results show that the joint inversion strategy leads to the most stable prediction of AI and porosity distribution in the lower Goru heterogeneous reservoir of Sawan Gas Field, Pakistan. The calibration of the individual spatial distribution of lithology and porosity from wireline logs data using Gaussian simulation algorithms and post-stack seismic inversion using SVM and PSO; revealed favorable matching. In fact, the spatial pattern of low AI corresponds with the high porosity and sandstone lithofacies. The study results provide valuable insights for identifying the sweet spots in the heterogeneous lower Goru clastic packages of Sawan Gas Field through quantitative analysis of rock physics, petrophysics, seismic inversion, and fuzzy optimization. The proposed joint inversion strategy may be considered useful for the prediction of porosity in similar context of extremely heterogeneous stratigraphic traps in other basins of the world.

Petrophysical parameters of a petroleum reservoir rock, used in formation evaluation, are generally estimated from wireline logs and core plugs. However, uncertainty or percentage error in quantitative interpretation of wireline logs and petrophysical parameters is generally not well quantified. Formation evaluation analysis and rock physics modeling are very useful techniques to link physical properties of reservoir interval extracted from wireline logs at well location with petrophysical, elastic and seismic properties of the reservoir interval far away from the well location. However, several types of uncertainty in the estimation of these parameters can affect this link seriously. In this work, a complete workflow is proposed to find out various petrophysical and rock physics parameters and to estimate percentage error in the extraction of these parameters. This work flow is based on traditional wireline log interpretation and is successfully applied on Basal sands of four wells drilled in the lower Indus Basin of Pakistan. An uncertainty analysis using statistical techniques is performed on different petrophysical parameters such as volume of shale, porosity, permeability estimated from wireline logs of these wells. Based on our statistical approach, linear and nonlinear regression relationships are developed between different petrophysical parameters. Furthermore, these parameters are used as input in rock physics model to predict elastic moduli and seismic velocities of the reservoir interval. The rock physics parameters such as velocities, densities and elastic moduli derived from well data are in close agreement to those predicted from rock physics model.

Mansehra Granitic Complex (MGC) lies in the NW Himalaya of Pakistan. The MGC magmatic rocks are peraluminous, calc-alkaline S-type granitoids. Prior to this study the Mansehra Granite had produced ages of 83 Ma by K/Ar, 215 Ma using Ar/Ar on biotite, and 516 ± 16 Ma, using the whole rock Rb/Sr method. The Susalgali Granite Gneiss, a sheared facies of the Mansehra Granite previously regarded as older than the Mansehra Granite, was dated at 79 Ma using K/Ar on biotite. Hakale Granite, which is intrusive into the Mansehra Granite, had yielded K/Ar muscovite age of 165 Ma. The age of the leucogranites was not reported before this contribution. We have presented the revised geochronology of the MGC magmatic bodies, employing SHRIMP and LA-ICP-MS U-Pb zircon chronometry, to constraint precise crystallization ages and tectonic setting of the NW Himalaya, Pakistan. Dates of emplacement of the Mansehra Granite, leucogranites and Hakale Granite are ca. 478, 475 and 466 Ma, respectively. These new ages are comparable to U-Pb zircon and Rb/Sr dates of other granites and granite gneisses in the Lesser Himalaya to the east, in India, Nepal, south Tibet and SW China. The age components of ca. 1900–1300, 985–920, 880–800 and 690–500 Ma are interpreted as inherited grains. Geochronological and field evidence suggest that the MGC of the NW Himalaya are the product of an Andean-type Cambro-Ordovician accretional orogenesis with continental-continental settings along the northen margin of east Gondwana. On the basis of new age data of the MGC plutonic rocks it is inferred that Cambro-Ordovician accretional event commenced from SW China and extends at least up to NW Pakistan along the northern margin of east Gondwana. However, granitic rocks of Pan African affiliation prevail in central Iran and Turkey along northern and western margins of Gondwana.

Delineation of saline water and freshwater interfaces is a primary objective in groundwater studies and groundwater management. Karak valley, NW Himalaya of Pakistan is situated in a semiarid region where the continuous supply of freshwater is challenging because of high salinity values in groundwater. In this study, vertical electrical resistivity and borehole data are used to mark the freshwater and saline water interfaces. Borehole data collected from different locations in the study area is used to interpret various subsurface lithologies and to calibrate the modeled resistivity curves. The electrical resistivity data indicates that a thick cover of Quaternary sediments is present in the valley. The re-inversion of electrical resistivity data with modern analysis techniques is highly effective to map the boundary between fresh and saline water aquifers in the valley. Inversion technique is applied to generate 2D and 3D subsurface resistivity maps for the delineation of fresh and saltwater surfaces. The presence of saline water aquifer with clay rich sediments is identified by very low resistivity values on the northern part of the valley whereas relatively high resistivity values with sand and gravel sediments on the southeastern part of the valley indicate the presence of freshwater aquifer. The generated 2D resistivity surface maps at different depth levels above and below the water table and formation resistivity distribution map are effectively used to mark the boundary between fresh and saline water zones. The zone of brackish water is clearly seen in the resistivity inverse model at a depth of 5–30 m.

Gas hydrates gained a remarkable attention as an unconventional energy resource recently. In order to interpret gas hydrates (part of fluid) and free gas saturated zone accurately, it is essential to implement new technique related to seismic attenuation and velocity dispersion. P wave attenuation and velocity dispersion in porous media made promising imprints for exploration of gas hydrates. The most prominent phenomenon for attenuation and velocity dispersion in porous media is wave induced fluid flow in which wave inhomogeneities are larger than pore size but smaller than wavelength. Numerical simulation technique is applied to analyze frequency dependent velocity dispersion and attenuation in gas hydrates and free gas layer in Makran offshore of Pakistan. Homogeneous and patchy distribution patterns of gas hydrates and free gas within pore spaces of host sediments at lower and higher frequency regime are considered. It is noted that the attenuation and velocity dispersion increase with the increase in gas hydrates saturation. The maximum attenuation is observed at 66% saturation of gas hydrates in the area under investigation. However, in case of water and gas mixture the maximum attenuation and velocity dispersion occur at low gas saturation (~15%). Therefore, based on our numerical simulation, velocity dispersion and attenuation can be used as seismic attributes to differentiate various gas saturations and gas hydrates saturation for Makran offshore area of Pakistan.

Sandstone intervals of the Lower Goru Formation of the Cretaceous age are proven reservoir intervals in the middle Indus Basin, Pakistan. However, based on seismic data interpretation, it is difficult to differentiate payable gas sand from non-payable gas sand. Various types of post-stacks seismic attributes are extracted and analyzed to differentiate payable gas sand from non-payable. The analysis reveals that average instantaneous frequency, peak spectral frequency, average instantaneous phase and sweetness seem to be more effective attributes along with energy half time. Sweetness attribute map shows two sweet spot below the targeted window which indicate to the presence of gas play. Statistical analysis is also carried out to find the associations between seismic attributes and thickness of gas layer values. Cross plots of these attributes were quantified through regression analysis. A good correlation with regression coefficient (R2) > 0.78 is found between seismic attributes and gas layer thickness except average instantaneous phase attribute, which lays the foundation for predicting the thickness of gas reservoir.

Lower Goru sand intervals of the Cretaceous age in Kadanwari field of the middle Indus Basin, Pakistan, are interpreted as reservoir intervals. Based on seismic interpretation and geology, several wells were drilled in these sands. However, most of the wells drilled were dry and declared abundant because highly saturated brine was encountered with minute amount of hydrocarbon gas. The main reason for drilling dry wells was limitation of seismic reflection data to differentiate seismic response of hydrocarbon-saturated reservoir interval from non-hydrocarbon-saturated interval. Amplitude versus offset (AVO) analysis is widely used to differentiate hydrocarbon intervals from background lithology. In this work, AVO-derived attributes are used for fluid discrimination in the sand intervals. Amplitude differences are associated with density and compressibility of fluid under in situ temperature and pressure conditions of the reservoir interval. The results reveal that seismic amplitude anomalies associated with AVO analysis can differentiate hydrocarbon fluids from non-hydrocarbon fluids and thus can optimize the exploration of gas. The gas sand anomaly in the study area is of weak impedance as compared to brine sand. The intercept and fluid factor are very promising attribute pairs to discriminate gas sands from background sands. The results may be helpful to discriminate low gas saturation or fizz water from high gas saturation.

Petrophysical properties of rocks can be better understood by core and well log analysis. Exact porosity estimation in the Potwar sub-basin of Pakistan is one of the main issues because of complex tectonic settings. Core and wireline log data of two wells: Injra–1 and Nuryal–2 drilled in the study area are used for the porosity evaluation in the Jurassic reservoirs. The log interpretation and laboratory analysis show that the Datta Formation of the early Jurassic is mainly sandstone with minor shaly beds. A workflow is developed to correlate the calculated porosity from logs with the measured porosity from core plug samples. The results show that log porosity and core porosity of Datta sandstone are comparable. Porosity in the younger formations is higher than in the older formations, which is an indication of presence of secondary porosity and structurally deformed fractures in sandstone. The Datta sandstone encountered in Nuryal–2 is about 20–30 % less porous than in Injra–1 well.

Partially saturated reservoirs are one of the major sources of seismic wave attenuation, modulus defect and velocity dispersion in real seismic data. The main attenuation and dispersion phenomenon is wave induced fluid flow due to the heterogeneity in pore fluids or porous rock. The identification of pore fluid type, saturation and distribution pattern within the pore space is of great significance as several seismic and petrophysical properties of porous rocks are largely affected by fluid type, saturation and fluid distribution pattern. Based on Gassmann-Wood and Gassmann- Hill rock physics models modulus defect, velocity dispersion and attenuation in Jurassic siliclastic partially-saturated rocks are studied. For this purpose two saturation patterns - uniform and patchy - are considered within the pore spaces in two frequency regimes i.e., lower frequency and higher frequency. The results reveal that at low enough frequency where saturation of liquid and gas is uniform, the seismic velocity and bulk modulus are lower than at higher frequency where saturation of fluid mixture is in the form of patches. The velocity dispersion and attenuation is also modeled at different levels of gas saturation. It is found that the maximum attenuation and velocity dispersion is at low gas saturation. Therefore, the dispersion and attenuation can provide a potential way to predict gas saturation and can be used as a property to differentiate low from high gas saturation.

Graphene-based nanocomposite materials have drawn the serious attention of researchers due to their remarkable applications in the field of energy storage. Here, in the current work, the authors prepared various composite electrode materials composed of iron oxide and reduced graphene oxide. A simple cost-effective and one-step hydrothermal approach was employed, for the first time, using a combination of two reducing agents, namely urea and starch. The formation of composite materials was characterised using scanning electron microscopy and X-ray diffraction. The electrochemical characteristics of the as-manufactured composite materials were explored using cyclic voltammetry and galvanostatic charge/discharge tests. It was found that the iron oxide–reduced graphene oxide composite prepared by using two reducing agents exhibits higher specific capacitance (286.6 F g− 1) at scan rate of 5 mV s− 1 in 1M KOH solution.

The Khewra Sandstone is widely distributed throughout the Potwar Basin of Pakistan. Its reservoir aspects are evaluated by the interpretation of well log data recorded from Kal-01 and Kal-02 wells in the Kal Oil Field, eastern Potwar Basin. The encountered thickness of the Khewra Sandstone in Kal-01and Kal-02 varies from 60 m to 120 m. On the basis of lithological interpretation from wireline logs the formation is divided into four facies: 1) shale interbedded with minor siltstone and sandstone, 2) sandstone with alternating siltstone and claystone/shale, 3) claystone/shale, siltstone interbedded with fine to medium grained sandstone and 4) fine to coarse grained sandstone with channels. The log derived average porosity in Khewra Sandstone is about 14–22% with permeability ranges from 20–58 mD. Thus, it possesses a large storage capacity for moveable hydrocarbons in Kal Oil Field. Facies 4, in the upper part of the Khewra Sandstone, is interpreted as potential reservoir interval with hydrocarbon saturation ranges from 77–79%. Based on isopach map, the formation is interpreted to be well developed in NE-SW which gradually thins basinward to the west and northwest direction. The play fairway analysis suggested very high chances of hydrocarbon entrapment is in the Kal Oil Field.