Browsing by Author "Yasin, Qamar"

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    An integrated fracture parameter prediction and characterization method in deeply-buried carbonate reservoirs based on deep neural network
    (Journal of Petroleum Science and Engineering, 2022) Yasin, Qamar; Ding, Yan; Baklouti, Syrine; Boateng, Cyril D.; Du, Qizhen; Golsanami, Naser; 0000-0002-1721-4158
    However, fracture prediction in deeply buried carbonate reservoirs has always been challenging. Fracture prediction in the deep-buried carbonate structure of North China is problematic because of multiphase tectonic movements, variable sediment lithology, and complex diagenesis. Because of deep burial depth and complex heterogeneity, the resolution of seismic reflection data beneath the buried-structure is poor, making it challenging to identify the fault reflection characteristics. This paper proposes a novel idea to identify natural fractures in carbonate reservoirs using conventional logs with seismic reflection data. The proposed model can also predict the fracture aperture and fracture density, a distinctive feature. Another novel hybrid model based on deep-learning neural network (DNN) and cluster analysis is proposed to predict further the spatial variations of lithology, porosity, and fracture parameters from seismic inversion. The proposed models provide valuable insights that help determine fracture parameters in the Paleozoic strata and associated reservoirs through quantitative analysis using petrophysics, rock physics, seismic inversion, and seismic attributes. The overlapping of seismic interpreted fault networks and spatial variations of the inverted fracture parameters indicate a high correlation of fracture development zones. The methodology proposed in this study presents a valuable template valid for the characterization of fractured reservoirs in deeply-buried carbonate reservoirs throughout the world.
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    Evaluation of shale gas reservoirs in complex structural enclosures: A case study from Patala Formation in the Kohat-Potwar Plateau, Pakistan
    (Journal of Petroleum Science and Engineering, 2021) Yasin, Qamar; Baklouti, Syrine; Khalid, Perveiz; Ali, Syed Haroon; Boateng, Cyril D.; Du, Qizhen; 0000-0002-1721-4158
    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 < 2500 m. This study emphasizes the critical role of the sealing mechanism in shale gas reservoirs. Furthermore, the results suggest that the evaluation and development of shale gas potential using petrophysical and geochemical analysis may be inadequate. Further scrutiny of the roof and floor of reservoirs’ efficient sealing capacities is essential to understand the extent of shale gas preservation and enrichment. The study results provide valuable insights for identifying the sweet spots and preservation condition of shale gas in the Kohat-Potwar Plateau of Pakistan.
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    Study on brittleness templates for shale gas reservoirs-A case study of Longmaxi shale in Sichuan Basin, southern China
    (Petroleum Science, 2021) Yasin, Qamar; Sohail, Ghulum Mohyuddin; Liu, Ke-Yu; Du, Qi-Zhen; Boateng, Cyril D.; 0000-0002-1721-4158
    Differentiating brittle zones from ductile zones in low permeability shale formations is imperative for efficient hydraulic fracturing stimulation. The brittleness index (BI) is used to describe the rock resistance to hydraulic fracture initiation and propagation and measures the ease at which complex fracture net works can be created. In this study, we constructed brittleness templates through the correlation of fundamental rock properties and geomechanical characterization. We then employed the templates to distinguish the brittle, ductile, and brittle-ductile transition zones in the Longmaxi shale gas reservoir, Sichuan Basin of southern China. The approach works in two steps. First, we suggest a new expression for the mineralogical BI by their respective weights based on the analysis of correlation coefficients between mechanical testing and XRD results. Second, we correlate TOC, porosity, pore fluid, natural fractures, and improved BI model with multiple elastic properties to define the brittle, ductile, and transitional zones in the Longmaxi shale gas reservoir of China. Compared with the traditional mineralogy-based BI definition, the improved BI model differentiates the brittle and ductile zones and provides a better sense of the most suitable fracturing regions. Our results show that the brittleness templates, which combine fundamental rock properties, improved BI model, and geomechanical characterization led to identifying favorable zones for hydraulic fracturing and enhanced shale characterization. The proposed brittleness templates’ effectiveness was verified using data from horizontal wells, offset wells, shale gas wells from different origins, laboratory core testing, and seismic inversion of BI across the studied wells.