Oil & Gas Development Company

Using orange peels as a biowaste, fluorescent N-CDs were prepared simply and rapidly through a one-step microwave-assisted method and urea as a nitrogen source. The synthesized N-CDs exhibited a high QY value of 47.12% compared to CDs prepared using different methods. Moreover, the N-CDs have good pH and thermal stability. N-CDs exhibited high sensitivity toward Fe(III), Hg(I), and Hg(II) ions with low LOD values of about 0.0555, 0.15379, and 0.02505 mu M, respectively. This approach is hopeful for the large-scale formation of N-CDs and could encourage their utilization as fluorescent chemosensors due to their affordability, simplicity, high efficiency, and environmental friendliness.

Abstract True crystallization temperature (TCT) or salt saturated temperature is a primary consideration while using the heavy weight mixture brines due to risk of precipitation. In instances where density has to be increased using divalent brines mixture of Calcium Bromide and Calcium Chloride (CaBr2-CaCl2), TCT is determined by Bromide-to-Chloride ratio. This paper describes management of TCT at an exploratory well in Northern Pakistan well where Calcium Bromide and Calcium Chloride (CaBr2-CaCl2) mixture was successfully used below TCT conditions. The operational requirement of going at 1.8 SG with available Calcium Bromide brine and unavailability of Zinc Bromide (ZnBr2) due to long lead time, underlined the utilization of blended Calcium Bromide and Calcium Chloride system. The blend weight at saturation points increased TCT from -10°C for pure Calcium Bromide to 16°C with risk of crystallization. Extensive laboratory testing and risk assessment were performed to confirm crystallization at varying temperatures and a placement strategy of brine weights as per crystallization trend was implemented. Required temperature was maintained at surface storage as well, to prevent crystallization. The displacement from oil-based mud (OBM) to brine was executed as per plan, with all testing and completion operations — including 11 perforation runs, drill stem tests and completion operations were carried out smoothly. With detailed lab testing and risk assessment, all steps of brine preparation, displacement and operations were successfully completed on-site without any crystallization incidents, despite ambient temperatures reaching 4°C which was less than TCT. This operation marks one of the first successful field deployments in Pakistan of a Calcium Bromide + Calcium Chloride (CaBr2-CaCl2) brine system at saturation point and below TCT without crystallization. The job demonstrated the effectiveness of integrating careful brine management practices, real-time temperature control, and strategic displacement sequencing. The lessons learned and methodology adopted set a new operational benchmark for high-density brine completions in exploratory/wildcat wells where heavier brine cannot be secured due to urgent requirements.

Abstract The success of ESP completions depends on precise well architecture, reservoir conditions, and formation characteristics. In 2025, Well-X underwent a workover with ESP installation guided by simulation modelling. However, suboptimal ESP placement at a shallower depth led to significant sand ingress, choking 50% of the pump and causing operational challenges. This paper discusses the resulting equipment damage, chemical mitigation strategies, and formation-specific operational challenges. Well-X was drilled in April 2016 to a total depth of approximately 3740 meters, targeting the Khewra, Jutana, Tobra, and Eocene formations. Only Tobra Sandstone formation proved productive, where an additional interval was perforated. Initial flow yielded 150 BPD oil, 0.085 MMSCFD gas, API gravity of 26.3°, water cut of 1.9%, and sand content of 0.1%. After producing 13,379 barrels, the well ceased flowing on 23 December 2016. Multiple rigless jobs (Xylene + HSD wash & N2 kick-off) were attempted. A straddle jet pump was planned but abandoned due to fishing complications leading to the installation of ESP in July 2025. In July 2025, a rig was deployed for a workover to install the ESP system. Re-perforations in the Tobra formation were conducted to enhance productivity, followed by a stimulation job aimed at reducing formation skin and improving reservoir inflow. The ESP assembly—comprising a motor, three pumps, and accessories—was run with depth constraints the 7" liner top at 3296m. As a result the ESP depth was set at a shallower depth of 2806, raising concerns about the simulation model used for placement. Brine offloaded contained 4–5% crude oil and 1% sand. At high operating frequency (57 Hz), the ESP tripped repeatedly due to elevated motor temperatures (170°C and 182°C). Sand samples were sent to service companies for analysis to develop a solvent injection strategy to break sand and sludge bonds. Ongoing work emphasizes better depth modelling with specialized chemical treatments to enhance ESP reliability in sandstone reservoirs. This case study highlights the potential of ESP completions to revolutionize artificial lift strategies in Pakistan. A comparable well from the same client demonstrated a 75% production increase (from 840 to 3300 BPD) after ESP installation, underscoring the importance of accurate modeling and optimized pump placement. This case illustrates the significance of simulation accuracy, formation-specific solvent strategies, and optimization of pump placement for extended ESP performance in a sand-bearing zones. These findings provide a basis for guidelines to install ESP in similar geological settings.

The Surghar Range lies on the Kohat Plateau within the Upper Indus Basin and has considerable hydrocarbon-producing potential because of the presence of a large amount of organic matter (OM), valuable stratigraphy and complex structural traps. From the Permian period to the Pliocene period the stratigraphic sequence in the area developed a range of reservoir rocks, source rocks and seals which are the essential components of an effective petroleum system. The various depositional conditions found in important sections such as the Tertiary clastic rocks, the Mesozoic carbonate rocks and the Permian sandstones are conducive to the accumulation of hydrocarbons, and the complex structural traps produced by tectonic activity also improve the region’s exploration prospects. Organic geochemical analysis shows that the Sembar and Patala formations are the principal source rocks for hydrocarbons in the Surghar Range and Kohat Plateau, the Sembar having a TOC value of 1.60–2.20 wt

Understanding reservoir heterogeneity in siliciclastic systems requires integrated analysis across multiple scales. This study investigates the Early Cretaceous Lower Goru Formation in the Lower Indus Basin using a multiscale integrated approach that combines seismic stratigraphy with pore-scale characterisation to constrain depositional environments, sequence architecture, pore system, mineralogy and diagenetic evolution. This study provides the first integrated framework linking seismic-scale stratigraphy to pore-scale diagenesis in the Lower Goru Formation, enhancing reservoir quality prediction in mature exploration settings. An integrated workflow of core description, petrophysical analysis, petrography, SEM, and 2D seismic data is employed to delineate stratigraphic architecture and depositional trends. Reservoir heterogeneity is assessed through an evaluation of depositional and diagenetic controls, while machine learning-based classification enhances facies prediction and strengthens interpretive reliability. Based on core analysis, four facies associations were identified within the reservoir succession, including shoreface, mouth bar, and shelf delta lobe facies associations. The Lower Goru Formation comprises one second-order sequence and nine third-order sequences within the studied reservoir interval. Petrographic analysis reveals that the sandstones are fine to medium grained and moderate to well-sorted reflecting a relatively uniform grain size distribution. Their mineralogical composition is diverse comprising litharenite, feldspathic arenite and quartz arenite. SEM observations reveal a complex pore system comprising primary intergranular macroporosity, secondary intragranular macropores, and intercrystalline micropores, which collectively exert a strong influence on reservoir storage capacity. Diagenesis led to the formation of chamosite and ooids that developed chlorite coatings which inhibited extensive quartz overgrowths while subsequent matrix recrystallisation produced microporous chlorite that further influenced reservoir properties. These integrated findings provide critical insights into the sequence stratigraphy and facies distribution of the Cretaceous sedimentary system and offer valuable guidance for hydrocarbon exploration in the Indus Basin.