Oil & Gas Development Co. Ltd.

Seismic attributes can play an important role in the exploration of hydrocarbon-bearing stratigraphic systems. Incised valley systems are developed during the falling sea, which causes the deposition of coarse-grained sandstone facies inside the low-standing tracts (LST). These regional phenomena constrain the quantitative attributes of ultra-thin-bedded stratigraphic petroleum traps, e.g., vertical and lateral variations in the thickness, accommodation space, lithology, and porosity. This study deals with the application of the continuous wavelet transform (CWT) of a spectral decomposition (SD) tool on a 3D post-stack seismic volume of the Miano gas Field, Lower Indus basin, Pakistan. The results show that the CWT accurately detected the regionally faulted/fractured system and distinguished the frequency-dependent amplitude anomalies. The wedge model resolved a 24-meter-thick gas-bearing resource. Quality control analysis was carried out using CWT-based broadband processing between the designed amplitude spectrum of 17 Hz and 70 Hz. The reservoirs with over 25% porosity that were located within the shale-dominated facies with less than 8% porosity were imaged through the processing of the instantaneous spectral porosity model at the 48-Hz tuning block. Moreover, 190 to 165-m-thick thin-bedded sandstone reservoirs at a 25% porosity zone were resolved using 22-Hz and 28-Hz, which implicates the sea standstill and medium-to-coarse-grained depositional reservoir facies. The ultra-thin-bedded traps inside the laterally continuous stratigraphic lens of 121 m and the prograding clinoform lens of 101-m within the incised valley petroleum system were resolved using 48-Hz, which implicates the falling sea and fine-scaled transgressed erosional facies. These implications suggest that the identified regional stratigraphic traps have development potential for this gas field. The treatment of the inverted model at the highest frequencies can be utilized to investigate the porous stratigraphically trapped facies of LST and can serve as an important analogue for the leading gas field of the Indus Basin and similar basins.

Due to concerns over rising emissions of carbon dioxide (CO₂) from fossil fuel utilization, there has been a strong emphasis on the development of a safe, economical, practical method of carbon capture utilization and storage (CCUS). One way to reduce these CO₂ emissions is underground geological sequestration in depleted oil fields or exhausted reservoirs. CO₂ injection into oil reservoirs is an established technology, these reservoirs not only offer the potential for high storage of CO₂ but this process could also target a large amount of oil and gas recovery through a technique called enhanced oil recovery (EOR). The main objective of this research was to evaluate the storage potential of CO₂ in the depleted oil field while also investigating the effect of CO₂ injection on reservoir pressure maintenance, and additional oil and gas recovery, in the same field. This paper presented the model of CO₂ flooding based on the CO₂ displacement mechanism with different scenarios of natural depletion, CO₂ injection, and water injection simulated by the ECLIPSE 300 reservoir simulator, and the results of different scenarios were compared. Results of this study showed the site selected for CO₂ injection has the potential to store more than 9 billion cubic feet (BCF) of CO₂ in each case and witnessed improved gas recovery, while also having a major effect on reservoir pressure maintenance where pressure increased from 2120 psi to 6584 psi. The finding of this work ought to help in preparing for future improvement in underground geological sequestration of CO₂ in depleted fields with the same field specifications.

The Lower to Middle Jurassic sedimentary succession of the Indus Basin, Pakistan represents thick strata of shale, siliciclastic and carbonate rocks.The shale is subjected to the exptl. methods of total organic carbon contents (TOC), rock-eval, vitrinite reflectance, and x-ray diffraction with clay mineralogy for identification of high potential source rock.This set of black shale having well-defined kerogen types I and II, an abundance of organic matter =2%, HI = 150 or 200 mg HC/g TOC, T_max = 465 °C, good maturity such as 1.3-2.0 Ro%, thermal alteration index =2, and spore color index =5, and illite-smectite clay is strong enough (60-80%) to produce hydrocarbon.Furthermore, the stratigraphic thickness is = 100 m in studied strata in a depth of 3500-4500 m in the Indus Basin feasible for future exploration.The chem. composition of black shale is siliceous mudstone, calcareous mudstone, argillaceous mudstone, and siliceous marlstone.The cross plot of OI vs. HI and T_max vs. HI shows mature types II and I kerogen while the cross plots of TOC vs. S₁ + S₂ with TOC vs. generative potentials (GP) showing good to high potentials of indigenous hydrocarbons.The plotting of the T_max vs. productive index (PI) exhibits that the kerogen mostly lies in the mature zone, having the capacity of oil generation.Besides the geochem. properties, the studied rock is thick and widely disturbed across the Indus Basin deposited under the dysoxic-anoxic setting.Moreover, the Lower to Middle Jurassic strata are correlated with the equivalent stratigraphic formations in India and China for their importance in the regional context.