Reservoir characteristics of Datta Formation (Early Jurassic), Marwat-Khisor Ranges, sub-Himalayas, Pakistan

The present work has been accomplished to carry out a detailed study of the characteristics of the Early Jurassic Datta Formation of Trans-Indus Ranges, Pakistan. The discovery of Saib well-1 (Gas and condensate discovery from Jurassic limestone) in the study basin takes an active interest in carrying out extensive exploration activities in the same basin. Jurassic rocks especially Datta Sandstone and Samana Suk Limestone are acting as good reservoirs. The study unit consists of variegated sandstone interbedded with siltstone, carbonaceous clay, and shale and coal stringer. For the current work, two stratigraphic sections (Pezu and Abbo Wanda) have been measured. To examine its sedimentology, depositional environment, diagenetic settings, and reservoir characteristics, a detailed study was conducted and various laboratory techniques have been utilized. About 95 rock samples from the bottom to the top of both sections were collected, and 50 rock samples have been selected for thin section analysis and were examined under a polarizing microscope to show their mineralogical composition, diagenesis, and their reservoir characteristics. XRD (X-ray diffraction), Cathodoluminescence (CL), SEM (Scanning electron microscope) with EDS (Energy-dispersive spectroscope), and Core plug porosity and permeability analysis have been used to interpret its chemical and mineralogical composition and its reservoir characteristics, respectively. Based on field observations and thin section analysis, four depositional facies and six lithofacies have been established. The sedimentary structures, depositional facies, and lithofacies indicate that Datta Formation was deposited in a deltaic environment. Compactions, cementation, fracturing and dissolution can greatly affect the quality of reservoir rock. Based on thin section and SEM analysis, large numbers of primary pores, fracture and secondary pores were observed and connectivity between the pores is good, and at some places, these pores were filled through the authigenic clay minerals like kaolinite, mixed layers illite/smectite and chlorite that influences the reservoir characteristics. Primary pores (thin section) and secondary pores (dissolution pores) and core plug porosity and permeability data (porosity 13.23%-26.89% and permeability 0.12 to 149 mD) shows that Datta Formation has a good reservoir quality.

Origin of Quartz Cement in the Paleogene Sandstone Reservoir of Shahejie Formation,Bohai Bay Basin,China

The precipitation of authigenic quartz plays a significant role to reduce the reservoir characteristics and enhance the stiffness of the rock.The Es_(1) sandstone of Shahejie Formation is acting as a significant hydrocarbon producing rock in the Nanpu Sag.Various methods like thin section petrography,cathodoluminescence(CL),scanning electron microscope(SEM,with EDS),and electron microprobe analysis has been used to reveal the origin of quartz cement as well as to evaluate the effect of quartz cement on reservoir quality.The studied sandstone is classified as immature to mature feldspathic litharenite and lithic arkose and consists of quartz,feldspar,rock fragments and micas.Petrographic studies and SEM analysis shows that the authigenic quartz is acting a significant cement that reduces the reservoir quality.Whereas clay minerals(kaolinite and mixed layer illite to smectite)are dominant in the Es_(1) sandstone,that can reduce the reservoir quality.SEM,CL and thin section analysis reveal that there are two stages of quartz cement in the studied samples;that are pore filling authigenic cement and quartz overgrowth cement.Fluid inclusion homogenization temperatures shows that stages of quartz cement were developed with continuous process from 70℃ to 130℃.Quartz cements were generally originated from I/S reaction,feldspar dissolution,conversion of rock fragments and pressure solution.Feldspar dissolution(K-feldspar)and kaolinite to illite reaction is an insignificant silica source for the silica cement which is internally precipitated in a close system with diffusion transporting mechanism.Overall,quartz cement significantly enhance the rock strengthen and brittleness effectively as well as it reduce the overall reservoir quality.

Indoor Air Quality Measurement with the Installation of a Rooftop Turbine Ventilator

The present paper presents a numerical analysis of the difference in comfort level inside a room of a residential building when roof top turbine ventilator is installed. This analysis simulates various comfort factors which includes the indoor air movement, room temperature, Predicted Mean Vote (PMV) and Predicted Percentage of Dissatisfied (PPD). Various test cases of ventilator exhaust rate were examined. The results showed that general comfort satisfying international standards in building can be achieved. This study also presents a qualitative and quantitative study of indoor air temperature and overall indoor air flow pattern. A promising conclusion that can be drawn from this study is that wind driven ventilators can play an important role in the design of a cost effective and energy efficient ventilation system inside a building.