Brahim Si Ali

A critical analysis on palm kernel shell from oil palm industry as a feedstock for solid char production

Abstract Palm kernel shell (PKS) is one of the greatly abundant residues in the palm oil industry. It possesses physiochemical characteristics that build in it a potential to serve the production of valuable products, namely, bio-fuels such as char, bio-oil, and bio-gas. This paper presents the properties of PKS as a biomass feed for the production of char. Characterizations of PKS in terms of proximate and ultimate analyses, chemical composition, and higher heating value (HHV in terms of MJ/kg) are presented and consequently compared to different oil palm biomass such as empty fruit bunch (EFB), fiber, fronds, and trunks. To illustrate and signify stability, the aforementioned characteristics are discussed for PKS-char, along with further comparison with EFB-char and coal. In addition, recent advances in char production methods from PKS are presented and compared. Simultaneously, future prospects and major challenges towards the utilization of PKS for the production of char are also addressed.

The Effects of Glass Bubbles, Clay, Xanthan Gum and Starch Concentrations on the Density of Lightweight Biopolymer Drilling Fluid

It is an open secret that currently oil and gas industry is focusing on increasing hydrocarbon production through underbalanced drilling (UBD) and finding ways to ensure the drilling process is less harmful to the environment. Water-based biopolymer drilling fluids are preferred compared to oil based drilling fluids owing to the fact that it causes less pollution to the environment. This paper investigates the effects of varying concentrations of environmentally safe raw materials, namely glass bubbles, clay, xanthan gum and starch concentrations on the density of the formulated biopolymer drilling fluid to ensure that it is suitable for UBD. As material concentrations were varied, the density for each sample was measured at ambient temperature and pressure. Results showed that the final fluid densities are within acceptable values for UBD (6.78 to 6.86 lb/gal). It is concluded that the formulated water-based biopolymer drilling fluid is suitable to be used in UBD operation.

Viscosity prediction model optimization for Saraline-based super lightweight completion fluid at high pressure and temperature

Investigation and analysis of the viscosity variation of Saraline-based super lightweight completion fluid (SLWCF) at high pressure and temperature were reported, and the viscosity prediction model was optimized. Viscosity measurements were carried out at temperature and pressure ranging from 298.15 K to 373.15 K, and 0.10 MPa to 4.48 MPa respectively. The data analysis reveals that the reduction of viscosity as a function of temperature may be divided into two regions, i.e. significant viscosity reduction at low temperature and fairly slow viscosity reduction at high temperature; the viscosity of Saraline-based SLWCF is less affected by the changes of pressure. The experimental data were fitted to four different viscosity-temperature-pressure models. The results show that, the modified Mehrotra and Svrceks and Ghaderis models are able to satisfactorily predict the viscosity value and measured value and describe the viscosity property at high pressure and temperature. The comparison with the Sarapar-based SLWCF reveals that the viscosity of Sarapar-based SLWCF is more affected by temperature than the Saraline-based SLWCF; pressure seems to have negligible effect on Saraline-based SLWCF viscosity; the modified Mehrotra and Svrceks and Ghaderis models are able to give more reliable viscosity predictions for Saraline-based SLWCF than for Sarapar-based SLWCF.

Novel Lightweight Biopolymer Drilling Fluid for Underbalanced Drilling

This research centres on optimizing the formulation of a water-based lightweight biopolymer drilling fluid using Design Expert for underbalanced drilling (UBD). Response Surface Methodology (RSM) was selected as a viable means to obtain the optimized drilling fluid formulation. Concentrations of four main raw materials (glass bubbles, clay, xanthan gum and starch) were varied in a suitable range to obtain the formulation with the desirable density, plastic viscosity (PV) and yield point (YP) for UBD application. Based on the results, the optimized drilling fluid can be formulated with 24.46% w/v of glass bubbles, 0.63% w/v of clay, 0.21% w/v of xanthan gum and 2.41% w/v of starch. The desirability factor, d for this optimum condition selected is 0.628. The mathematical models generated by RSM were able to predict the three response parameters well, as the experimental values were found to be in good agreement with the predicted values. The error is less than 1.0, standard deviation less than 0.5 and the accuracy is more than 98.5%. All mathematical models were quadratic in nature. The model used to predict the PV has an inverse square root transform. This drilling fluid is considered to be less harmful to the environment as it is water-based and, at the same time, composed of natural polymers (xanthan gum and starch) which are biodegradable. With this novel formulation, we could expect to drill more wells in underbalanced conditions to improve production of oil.

Density and Viscosity Prediction of Super Lightweight Completion Fluid SLWCF at Reservoir Conditions

This paper presents the effect of reservoir conditions, specifically temperature and pressure, on the rheological behavior and density of super lightweight completion fluid (SLWCF) for underbalanced perforation. In this study, fluid’s density was measured at various temperatures and pressure ranging from 313.15 K to 393.15 K, and 0.1 MPa to 25 MPa, respectively. Meanwhile, fluid’s viscosity was measured at temperature between 298.15 K to 373.15 K, and pressure range of 0.1 MPa and 4.48 MPa. In order to understand the effect of reservoir conditions to the density and viscosity of the fluid, experimental data were fitted to several density-/viscosity-temperature-pressure models and then the generated results were statistically evaluated. Based on the results, it is observed that the Tait-like equation was able to satisfactorily express the relationship between the density, pressure and temperature. The predicted density values based on the Tait-like equation are also in good agreement with the regressed model results. For the case of fluid’s viscosity, it is found that both modified Mehrotra and Svrcek’s and Ghaderi’s equation were the best equation for viscosity prediction. Using these equations, it is statistically possible to predict the variation of fluid’s density and viscosity over the wide range of pressure and temperature. Furthermore, it is also found that the predicted density and viscosity values are very close to the experimental data with very low deviation. This confirmed the reliability and accuracy of the prediction. This paper provides a novel data prediction of rheology and density of Saraline-based SLWCF at reservoir conditions for the purpose of underbalanced perforation. This result is essential as a tool for field engineers to roughly estimate the density and viscoplasticity of completion fluids as they subjected to reservoir conditions.