Mostafa G. Temraz

Lower Paleozoic reservoir zonation into different flow units using turbulence factor and their relations to diagenesis

Surface Lower Paleozoic sandstone samples were collected from southeast central Sinai. These samples subjected to petrophysical measurements which are porosity and permeability. It is known that turbulence factor (β) is a good tool to describe turbulent flow level, hence it was used to detect the flow properties distribution that corresponds to the nature of the pore system, so turbulence factor (β) was correlated with porosity, permeability, and reservoir quality index using many equations, where porosity correlation shows the presence of three groups having same porosity ranges but correspond to different values of turbulence factor, this refers to the presence of different flow zones. Porosity–permeability relation confirmed also the presence of similar three groups, where there are nearly same porosity ranges but with different permeability values. Consequently, samples with nearly same porosity values and representing the three groups were selected for capillary pressure by mercury injection to reveal the flow properties that characterize each group. Capillary pressure results confirmed that each group has their own pore system and flow regime. Petrography was done by optical polarizing microscope (OPM) through thin sections. The results indicated that the studied sandstone is composed mainly of quartz arenite microfacies of fine, angular to subrounded, moderately well sorted monocrystalline quartz grains. There are several features indicating that the investigated sandstones have been subjected to diagenesis processes. Diagenetic events identified in these sandstones include considerable compaction during burial diagenesis at higher temperatures and low flow rates, cementation by clay minerals and iron oxides, dissolution and alteration of unstable clastic grains, and tectonically induced grain fracturing. Unstable clastic grains like feldspars suffered considerable alteration to kaolinite when exposed to meteoric water of low ionic strength near the surface. The distribution of this kaolinite rather than the post-depositional iron oxides in pores of the studied sandstone leaded to differentiating these sandstones into three different flow units. This zonation indicates that the turbulence properties are proportional to the diagenetic effects inside the pores.

Miocene reservoir rocks: pore throat size distribution as a strong controller on petrophysical attributes is a reflection of facies change

Pore throat size distribution (PSD) is considered a finger print for each rock type and has strong effects on many petrophysical parameters, so a comparative study was done on irregular subsurface rock samples that belong to Kareem and Rudeis Formations of middle and early Miocene, respectively. These samples were collected from San El-Hagar-1 well which is located to the East of the Nile Delta to show the effect of the different lithologies on pore throat size distribution and hence many related reservoir parameters such as displacement pressure, macroporosity, microporosity, mean hydraulic radius and permeability distribution function (PDF). For achieving the previous purpose, helium porosity and capillary pressure by mercury injection were carried out. Permeability measurements were canceled due to the non-cylindrical irregular nature of the tested samples. Porosity showed a great difference between the results of the samples of the two formations. Capillary pressure results showed the presence of characterized pore throat size distribution and hence capillary pressure-derived parameters for samples of each formation. PDF showed that samples of Kareem Fm. have better reservoir flow properties (permeability) in contrast to those of Rudeis Fm. which have tight reservoir flow properties. In addition, petrographical study through thin sections and scanning electron microscope displayed the presence of two facies which are feldspathic quartz wacke (sandstone facies) of Kareem Fm. and bioclastic sandy wackestone (calcareous facies) of Rudeis Fm. All results were consistent and confirmed the influence of facies change on PSD and hence the reservoir parameters.

Preparation and characterization of black shale–reinforced ethylene propylene diene monomer nanocomposites:

Organophilic kaolinitic black shale was prepared through incorporation of cetyl trimethyl ammonium bromide (CTAB C16) as surfactant with natural kaolinitic black shale. It was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, and transmission electron microscopy. The acrylic acid modifying agent can be utilized to improve the distribution of the organophilic kaolinitic black shale in the rubber matrix. The ethylene propylene diene monomer was mixed with different concentrations of modified organophilic kaolinitic black shale. The dispersion of the modified organophilic kaolinitic black shale was characterized by scanning electron microscopy and X-ray diffraction, which confirmed the formation of exfoliated nanocomposites at lower clay content. The elastomeric compound was filled with kaolinitic black shale and then it was analyzed by undergoing the physicomechanical properties and thermal gravimetric analysis. The nanocomposites showed remarkable improvements in tensile strength, elongation at break, Young’s modulus, and hardness. In addition, increase in thermal stability due to the presence of modified organophilic kaolinitic black shale was observed.