The Effect of Biopolymer Chitosan on the Rheology and Stability of Na-Bentonite Drilling Mud

The utilization of greens resources is a grand challenge for this century. A lot of efforts are paid to substitute toxic ingredients of the conventional drilling mud system with nontoxic natural materials. In this paper, the effect of the natural polymer chitosan on the rheology and stability of sodium-bentonite drilling mud was investigated in the polymer concentration range of 0.1–3.0 wt.%. Both the shear and time dependent rheological properties of pure chitosan, pure bentonite and bentonite–chitosan dispersions were studied. Moreover, zeta potential measurements were used to evaluate the stability of bentonite-chitosan suspension. Adding chitosan improved the natural properties of drilling mud, namely: yield stress, shear thinning, and thixotropy. The viscosity of bentonite suspension increased significantly upon the addition of chitosan in the concentration range of 0.5 to 3.0 wt.% forming network structure, which can be attributed to the interactions of hydrogen bonding between -OH clusters on the bentonite surface with the NH group in the chitosan structure. On the other hand, dispersed chitosan–bentonite suspension was observed at low chitosan concentration (less than 0.5 wt.%). Increasing both bentonite and chitosan concentrations led to the flocculation of the bentonite suspension, forming a continuous gel structure that was characterized by noteworthy yield stress. The desired drilling mud rheological behavior can be obtained with less bentonite by adding chitosan polymer and the undesirable effects of high solid clay concentration can be avoided.

ENHANCED ASSESSMENT OF FLUID SATURATION IN THE WOLFCAMP FORMATION OF THE PERMIAN BASIN

Conventional resistivity models often overestimate water saturation in organic-rich mudrocks and require extensive calibration efforts. Conventional resistivity-porosity-saturation models assume brine in the formation as the only conductive component contributing to resistivity measurements. Enhanced resistivity models for shaly-sand analysis include clay concentration and clay-bound water as contributors to electrical conductivity. These shaly-sand models, however, consider the existing clay in the rock as dispersed, laminated, or structural, which does not reliably describe the distribution of clay network in organic-rich mudrocks. They also do not incorporate other conductive minerals and organic matter, which can significantly impact the resistivity measurements and lead to uncertainty in water saturation assessment. We recently introduced a method that quantitatively assimilates the type and spatial distribution of all conductive components to improve reserves evaluation in organic-rich mudrocks using electrical resistivity measurements. This paper aims to verify the reliability of the introduced method for the assessment of water/hydrocarbon saturation in the Wolfcamp formation of the Permian Basin. Our recently introduced resistivity model uses pore combination modeling to incorporate conductive (clay, pyrite, kerogen, brine) and non-conductive (grains, hydrocarbon) components in estimating effective resistivity. The inputs to the model are volumetric concentrations of minerals, the conductivity of rock components, and porosity obtained from laboratory measurements or interpretation of well logs. Geometric model parameters are also critical inputs to the model. To simultaneously estimate the geometric model parameters and water saturation, we develop two inversion algorithms (a) to estimate the geometric model parameters as inputs to the new resistivity model and (b) to estimate the water saturation. Rock type, pore structure, and spatial distribution of rock components affect geometric model parameters. Therefore, dividing the formation into reliable petrophysical zones is an essential step in this method. The geometric model parameters are determined for each rock type by minimizing the difference between the measured resistivity and the resistivity, estimated from Pore Combination Modeling. We applied the new rock physics model to two wells drilled in the Permian Basin. The depth interval of interest was located in the Wolfcamp formation. The rock-class-based inversion showed variation in geometric model parameters, which improved the assessment of water saturation. Results demonstrated that the new method improved water saturation estimates by 32.1% and 36.2% compared to Waxman-Smits and Archie's models, respectively, in the Wolfcamp formation. The most considerable improvement was observed in the Middle and Lower Wolfcamp formation, where the average clay concentration was relatively higher than the other zones. Results demonstrated that the proposed method was shown to improve the estimates of hydrocarbon reserves in the Permian Basin by 33%. The hydrocarbon reserves were underestimated by an average of 70000 bbl/acre when water saturation was quantified using Archie's model in the Permian Basin. It should be highlighted that the new method did not require any calibration effort to obtain model parameters for estimating water saturation. This method minimizes the need for extensive calibration efforts for the assessment of hydrocarbon/water saturation in organic-rich mudrocks. By minimizing the need for extensive calibration work, we can reduce the number of core samples acquired. This is the unique contribution of this rock-physics-based workflow.

Evaluation of the Mechanical Properties of Glass/Epoxy Composite by Embedding Shape Memory Alloy and Nanoclay

Embedding smart materials in the composite to enhance mechanical strength have become a research hotspot owing to their unique properties. The present research also focus on novel way to fabricate composite by embedding Shape Memory Alloy (SMA) wire and montmorillonite (MMT) nanoclay by varying clay concentration (0-7 wt.%). The extent of dispersion of nanoclay in epoxy resin was studied using Transmission Electron Microscopy (TEM) and X-ray diffraction (XRD). Fabricated samples were examined for tensile, flexural and impact characteristics. Scanning Electron Microscopy (SEM) was used to study the adhesion, delamination and damage occurred within the composite due to tensile loading. Results shows that the tensile strength, flexural strength and impact energy of SMA/MMT/glass/epoxy composite was improved by 23%, 21% and 57% respectively, when it was compared with composite with glass/epoxy composite.

Flocculation of Clay Suspensions by Anionic and Cationic Polyelectrolytes: A Systematic Analysis

The characteristics of clayey suspensions, majorly composed of quartz microparticles, in the presence of anionic and cationic polyelectrolytes were investigated using different techniques. A wide range of clay concentrations was used, i.e., from 0.07 to 1000 g/L for different experimental techniques, based on the fact that the clay concentration possible to analyze with selected experimental methods was significantly different. The optimum flocculant to clay ratio was defined as the ratio that gives the fastest initial floc growth by static light scattering or fastest initial settling velocity by settling column experiments. In case of anionic polyelectrolyte, it was observed that the optimum flocculant dose depends on the amount of cations present in the system. For suspensions made with demi-water, a lower optimum flocculant dose (<1 mg/g) than for suspensions prepared in tap water (2.28 mg/g) was observed. At these lower salinities, the supernatant remained turbid in all the experiments and was, therefore, not a good measure for optimal anionic based flocculation. The equilibrium floc size at a given shear rate was found to be independent on the shear history of the floc and only dependent on the current applied shear. This was confirmed by both light scattering and rheological analysis. In case of cationic polyelectrolyte, the optimum flocculant ratio (5–6 mg/g) corresponded to the ratio that gives the lowest electrophoretic mobility for each clay concentration and to the ratio that gives the fastest settling velocity for the highest clay concentrations (12–15 g/L), where static light scattering measurements were not possible. All investigation techniques, therefore, proved to be good indicators for predicting the optimum flocculant to clay ratio. For the lowest concentrations (1.75–8.7 g/L) studied by settling column measurements, the optimum flocculant ratio was observed to increase with decreasing clay concentration, for fixed mixing conditions. The optimum flocculant to clay ratio was not always corresponding to the clearest supernatant and the size of flocs at optimum dosage was dependent on the mixing efficiency. The equilibrium floc size at a given shear rate was found to be dependent on the shear history of the floc and the current applied shear. This was confirmed by both light scattering and rheological analysis.

Modelling and Experimental Investigation on the Settling Rate of Kaolinite Particles in Non-Ideal Sedimentation Stage under Constant Gravity

We compared the catalytic effects of two polymers (soluble starch and apple pectin) on the flocculation of kaolinite suspension. Moreover, the relationship between the zeta potential value and the time when kaolin particle sedimentation occurred was verified, and the mechanism of flocculation was analyzed. Additionally, a constitutive model was proposed to simulate the non-ideal sedimentation of clay particles in an aqueous system under constant gravity. This model not only considers the inhomogeneity of the solute but also simulates the change in clay concentration with time during the deposition process. This model proposes a decay constant (α) and sedimentation coefficient (s). The model can also be used to calculate the instantaneous sedimentation rate of the clay suspensions at any time and any depth for the settling cylinder. These sedimentary characteristics were simulated by adopting the established deposition model. The results show that the model is capable of predicting the time required for the complete sedimentation of particles in the aqueous system, suggesting the feasibility of engineering wastewater treatment, site dredging, etc.

Improvement of the Rheological and Filtration Properties of Drilling Mud Using the Syrian Clay

Drilling fluid properties and formulation play a fundamental role in drilling operations. The Classical water-based muds prepared from only the Syrian clay and water without any additives((Organic and industrial polymers) are generally poor in performance. Moreover, The high quantity of Syrian clay (120 gr / l) used in preparing drilling fluids. It leads to a decrease in the drilling speed and thus an increase in the time required to complete the drilling of the well. As a result, the total cost of drilling the well increased, as a result of an increase in the concentration of the solid part in the drilling fluid. In this context, our study focuses on the investigation of the improvement in drilling mud Prepared from the Syrian clay by reducing the clay concentration to (50 gr / L). And compensate for the remaining amount (70 gr / l) of clay by adding (natural and industrial polymers) The rheological properties and filtration are measured at different concentrations of polymers .. In light of the experiments, we determine the polymers' concentrations that gave good results in improving the flow properties and controlling the Filter. It is polymers that have given good results:، HEC، HEC and Xanthan Gum PAC and HEC، CMCHV، PolyAcryl Amid ، Xanthan Gum .

The fluxes and distribution of molybdenum in a mountainous fir forest in two hydrological years

<p>The distribution, stocks and fluxes of Mo were examined in a mountainous fir forest in Greece in two hydrological years. In both years, the fluxes of Mo in throughfall were lower than those in bulk deposition implying Mo retention and probably uptake by tree canopies. The Mo concentration was appreciable in soil solution but its fluxes were lower than those in throughfall. The Mo fluxes in both bulk and throughfall deposition were higher than those in litterfall, a finding that stresses the importance of the hydrological cycle for this metal. The Mo concentration in the older twigs in the standing trees were higher than the current year ones most probably due to the existence of dry deposition. The concentrations of total Mo in soils reflected the nature of the sedimentary rocks underlying the soil and increased with depth following the clay concentration gradient. The available (oxalate extractable) Mo in soils ranged from 3% to 14% of the total Mo. In terms of the stocks of Mo, the soil had by far the highest values in both total and available Mo. The needs of the fir plants for Mo uptake are covered by the available Mo in the mineral soil layers, whereas the Mo content in the organic horizon may not be adequate for this purpose.</p>

Mechanical Assisted Modification of Halloysite Nano Clay: Characterization and Its Effect on Mechanical Properties of Halloysite-Epoxy Nano Composites

Modificationof Halloysite nano clay has been done using 3-aminopropyltriethoxysilane in the presence of distilled water as solvent media. Untreated and modified nano clay was characterized by Powder X-ray diffractometer (PXRD), Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FT-IR). Functionalization of Halloysite nano clay is also strongly affected the morphological parameters and enabling the application in epoxy nano composite. However, the influence of modified clay concentration on the mechanical properties of epoxy/nanoclay composites, with different concentrations (2%, 3%, 4% and 5%) of nano clay in the epoxy resin was investigated. Experimental results showed that the mechanical properties of epoxy were improved upto 4 wt% of HNP’s, evidently because of the loading of modified clay. The tensile strength, tensile Modulus, flexural strength, flexural modulusand fracture toughness of the nanocomposites increased by 13%, 17%, 9%, 14%and 27% respectivelythis demonstrated that the composites were strengthened.

HUBUNGAN TEKSTUR SEDIMEN DAN BAHAN ORGANIK DENGAN MAKROZOOBENTOS DI HABITAT MANGROVE PANTAI TIRANG SEMARANG

ABSTRAK Pantai Tirang merupakan salah satu pantai di Semarang, terletak di sebelah barat dari bandara Ahmad Yani, pantai Maron dan Muara Kali Angke di Desa Tambakrejo, Kecamatan Tugu, Kabupaten Semarang. Tujuan dari penelitian ini adalah untuk mengetahui tekstur sedimen dan bahan organik, mengetahui nilai indeks biologi (indeks keanekaragaman, indeks keseragaman, dan indeks dominasi), dan mengetahui hubungan tekstur sedimen dan bahan organik dengan makrozoobentos di Habitat Mangrove Pantai Tirang Semarang. Metode yang digunakan dalam penelitian ini adalah: metode deskriptif (analisa lapangan dan laboratorium). Analisa lapangan di Pantai Tirang Semarang dan analisa laboratorium di Lab Pengelolaan Sumberdaya Ikan dan Lingkungan Fakultas Perikanan dan Ilmu Kelautan Universitas Diponegoro. Pengambilan sampel dilakukan 3 kali dengan interval waktu 2 minggu sekali. Hasil penelitian menunjukkan bahwa tektur sedimen didominasi oleh fraksi pasir berkisar 90,92-94,56% pada sampling pertama; fraksi liat 26,08 – 61,24% pada sampling kedua; fraksi liat berkisar 23,28-59,88 % pada sampling ketiga; dan Nilai bahan organik berkisar antara 1,88-5,88%. Nilai indeks keanekaragaman berkisar 0,563-1,003, indeks keseragaman berkisar 0,579-0,909, indeks dominasi berkisar 0,371-0,624 dan kelimpahan makrozoobentos berkisar antara 1995,27-5985,83 ind/m3. Jenis makrozoobentos yang mendominasi adalah dari genus Cerithidea. Hubungan tekstur sedimen dominan (fraksi clay) dan bahan organik dengan makrozoobentos: fraksi clay dengan kelimpahan makrozoobentos memiliki hubungan terbalik, semakin tinggi fraksi clay maka kelimpahan makrozoobentos makin rendah dengan koefisien korelasi -0,18. Bahan organik dengan kelimpahan makrozoobentos memiliki keeratan hubungan sedang, bahan organik makin tinggi maka kelimpahan makrozoobentos meningkat. Kata Kunci : Tekstur Sedimen; bahan organik; makrozoobentos; Pantai Tirang Semarang ABSTRACT Tirang Beach is one of the beaches in Semarang located at the westside of Ahmad Yani airport, Maron Beach and the estuari of Angke River, Tambakrejo village, Tugu subdistrict, Semarang Regency. The objective of the research is to determine the sediment textures and organic matters, to know the biological indices (diversity index, uniformity index, and the dominance index), and to determine the relationship between macrozoobenthos with sediment textures and organic matter in Mangrove habitat at Tirang Beach Semarang.This study adopts a descriptive method (Field and laboratory analysis). Field analysis in Tirang Beach Semarang and laboratory analysis at the Laboratory of Fish Resources Management and Environment Faculty of Fisheries and Marine Sciences, University of Diponegoro in Semarang. Sampling was conducted three times at intervals of 2 weeks.The results of this study shows that sediment textures is dominated by sand fraction ranged from 90,92 to 94,56% at fiirst sampling; clay fractions ranged from 26,08 to 61,24 % at second sampling; clay fraction ranged from 23,28-59,88 % at third sampling. Diversity index values ranged from 0,563 to 1,003, uniformity index ranges from 0,579 to 0,909, dominance index ranged from 0,371 to 0,624 and the abundance of macrozoobenthos from 1995.27 to 5985.83 ind/cm3. Macrozoobenthos is dominated by genus Cerithidea. Relation of sediment texture (clay fraction) and organic material with macrozoobenthos. The clay fraction and abundance of macrozoobenthos has a negative correlation, high clay concentration low macrozoobenths abundance and correlation value of -0.18. Organic matter and abundance of macrozoobenthos has a moderate correlation, high organic material high macrozoobenthos abundance and correlation value 0.73. Keywords: Sediment textures, organic matters; Macrozoobenthos; Tirang Beach Semarang