Muhammad Mushtaq

Static adsorption of anionic surfactant onto crushed Berea sandstone

Surfactant adsorption in porous media is one of the major criteria which decide the economic viability of surfactant flooding in chemical enhance oil recovery applications (CEOR). In this study, the static adsorption of a novel in-house synthesized anionic surfactant was investigated onto crushed Berea sandstone. The point of zero (PZC) charge for Berea sandstone and critical micelle concentration (CMC) of anionic surfactant are also reported in this paper. The investigated PZC for Berea core was at pH 8.0 and the maximum adsorption of anionic surfactant was 0.96xa0mg/g. Furthermore, the effects of alkali, salinity and temperature on static adsorption of anionic surfactant were investigated at variable conditions. It was concluded that the anionic surfactant performs better at higher pH, higher temperature and lower salt concentration. An effective control of all these parameters can lead to the situation which helps in minimizing the surfactant loss and improved economic efficiency of CEOR process.

Oleate Ester-Derived Nonionic Surfactants: Synthesis and Cloud Point Behavior Studies

The synthesis and cloud point behavior of high oleate ester-derived nonionic surfactants are now reported. The effect of various polyethoxylate chain lengths (polyethylene glycol with 7, 11, and 16 units of ethylene oxide (EO) monomer) as the surfactants hydrophilic head on the cloud point was investigated. The effect of varying amounts of sodium chloride and five different ionic surfactants on the cloud points of the synthesized nonionic surfactants were also presented. When the chain length of polyethoxylate increased, the cloud point of the synthesized nonionic surfactant also increased, ranging from 16°C, 43°C, and 64°C for 7, 11, and 16 EO units, respectively. Increments in sodium chloride concentration depressed the cloud point values of the synthesized nonionic surfactants linearly. The addition of ionic surfactants elevated the cloud points of the synthesized nonionic surfactant. However, in the presence of sodium chloride, the cloud point of the mixed ionic-nonionic solution was suppressed and anincrease in ionic surfactant concentration was required to elevate the cloud point. It was also found that the cloud points of synthesized surfactants can be raised up to 95°C in the presence of 4wt% NaCl solution.

Novel Surfactant for the Reduction of CO2/Brine Interfacial Tension

The synthesis of novel CO2 philic surfactant using maleic anhydride and dipropylene tertiary butyl alcohol is reported. The synthesis involved the esterification of maleic anhydride to produce bis(2-(2-(tert-butoxy)propoxy)propyl) maleate and subsequent sulfonation of the esterified product. Para toluene sulfonic acid was employed as catalyst for the esterification reaction. The esterification reaction was optimized for the maximum yield of 98% of bis(2-(2-(tert-butoxy)propoxy)propyl) maleate. The esterification reaction kinetics employing heterogeneous catalyst were also studied. Although this is a bimolecular reaction, a first order reaction kinetics with respect to acid has been observed. The activation energy was found to be 58.71 kJ/mol. The diester was followed by the sulfonation process and a yield of 85% of surfactant was achieved. The synthesized surfactant successfully lowered down the IFT between CO2/brine to 1.93 mN/m. This surfactant has a great potential to be used for CO2-EOR applications.

Synthesis of a New CO2 Philic Surfactant for Enhanced Oil Recovery Applications

The synthesis of CO2 philic surfactant using maleic anhydride and 4-tert-butylbenzyl alcohol is reported. We reacted maleic anhydride with 4-tert-butylbenzyl alcohol to form bis(4-(tert-butyl)benzyl) fumarate and sulfonated the produced diester. The esterification reaction was optimized for a maximum yield of 98% of bis(4-(tert-butyl)benzyl) fumarate. First-order reaction kinetics with respect to acid was observed. The activation energy was found to be 55.62 kJ/mol. The sulfonated product of diester was obtained by the sulfonation reaction and the yield of 82% of surfactant was achieved. The in-house developed surfactant effectively lowered down the IFT between CO2/brine to 4.2 mN/m. This surfactant is targeted for CO2-EOR applications.

A Convenient Route For The Alkoxylation Of Biodiesel And Its Influence On Cold Flow Properties

The attachment of alkoxy side chains to biodiesel and the associated effects on its cold flow properties are reported. High oleic methyl ester biodiesel was epoxidized using peroxy formic acid and subsequently alkoxylated using nine different alcohols employing BF3-ethereate complex as catalyst. A low molar excess for alcohols was used at moderately low reaction temperatures (40–50°C). A high conversion for attachment of alkoxy group ranging 84%–93% was achieved with excellent selectivity. Cloud points, pour points, and kinematic viscosities were measured to evaluate the cold flow properties of modified biodiesel. The lowest cloud point –11°C and pour point –14°C were obtained with n-decoxy biodiesel. Elevated kinematic viscosities were observed for all alkoxylated products. The lowest kinematic viscosity (6.26 mm2·s−1) was observed for methoxy biodiesel. Gas chromatography mass spectrometry (GC-MS), proton nuclear magnetic resonance (1H NMR), 13C NMR, and Fourier transform infrared (FT-IR) were used for structural elucidation. The reported alkoxylation route has high conversion rate and is convenient to implement.

CO2 Mobility and CO2/Brine Interfacial Tension Reduction by Using a New Surfactant for EOR Applications

The synthesis and use in enhanced oil recovery applications of a novel CO2-philic surfactant derived from maleic anhydride and 2-butyl-1-octanol is reported. The synthesis involved the esterification of maleic anhydride to produce diester followed by sulfonation of the esterified product. The esterification reaction parameters were optimized for the maximum yield of 98.4%. By employing a silica sulfuric acid catalyst, the reaction kinetics of esterification were also investigated. The activation energy was found to be 45.58 kJ/mol. The sulfonation reaction of the esterified product was performed by using sodium bisulfite, and a yield of 82% of surfactant was achieved. The synthesized surfactant lowered the interfacial tension between CO2/brine to 3.1 mN/m and effectively reduced the CO2 mobility. This surfactant has a great potential to be used for CO2 mobility control for CO2−EOR applications.

Influence of PZC (Point of Zero Charge) on the Static Adsorption of Anionic Surfactants on a Malaysian Sandstone

Static adsorption studies of two anionic surfactants produced in our lab are reported. The adsorption of surfactants on the rock samples was investigated with and without the presence of alkali. The point of zero charge (PZC) values were determined for the sandstone samples employing three titrimetric methods and it was found to be at pH 7.98. The relationship between the adsorption degree and pH value of brine below and above the PZC is discussed. It was found that at the pH of solution exceeds the PZC of the rock, the adsorption was 0.43 and 0.86mg/g of rock for the two surfactants. However, at pH values below PZC, the adsorption as high as 3.66 and 4.49mg/g for the two surfactants. The synthesized surfactants are found to be suitable for the EOR applications at pH values higher than the PZC of the rock sample.

Effect of pH on the static adsorption of foaming surfactants on Malaysian sandstone

Adsorption of surfactants on the reservoir rock is one the most important factors which decide the economic feasibility of recovery process. This study reports the adsorption of two in-house developed CO2-philic foaming surfactants on Malaysian sandstone. The point of zero charge (PZC) of the rock sample was determined to be 8.13. The surfactants contained single tail (FS-1) and two tails (FS-2) in their structures. Static adsorption tests were conducted as traditional bottle test as well as during the foam test experiments. For the bottle tests, it was noted that the FS-2 underwent more adsorption (4.94xa0mg/g) when compared to FS-1 (4.32xa0mg/g). The pH effect was significant, and at low pH value (pH 6), the adsorption was almost five times more for both surfactants when compared to the adsorption at high pH (pH 10) conditions. During the foam test at pH 6, the adsorption results for FS-1 and FS-2 were 4.02 and 4.48xa0mg/g, respectively. The effect of increasing the pH to 10 was comparable to bottle test results, and adsorption was decreased about five times. The bottle test gave slightly high adsorption values primarily because the contact time was longer (24xa0h) when compared to foaming test adsorption values where time is only about 30xa0minutes. In foaming tests, sparging of CO2 gas enhanced the shear mixing of contents thereby increasing the adsorption degree resulting in the similar adsorption values despite of less contact time. The study revealed that the adsorption of surfactant depends on many parameters, and one way of effective control is to adjust the pH of the fluid higher than the PZC of the rock.

Kinetics and Equilibria of Synthesized Anionic Surfactant onto Berea Sandstone

We present static adsorption studies of anionic surfactants on crushed Berea sandstone. The maximum adsorption density was 0.9604 mg/g. The kinetics of adsorption process was modeled using pseudo-first-order and pseudo-second-order rate equations at 25°C and 70°C. The equilibrium adsorption process was validated using Langmuir and Freundlich adsorption models. In addition, the effects of different parameters that govern the effectiveness of these surfactants such as pH and temperature were also investigated. The kinetic study results show that the surfactant adsorption is a time dependent process. The apparent rate constant of adsorption process determined by the first-order kinetic model at 25°C and 70°C were 0.11768 and −0.04513, respectively. The rate constant for pseudo-second-order kinetic model was 0.0086 at 25°C and 0.0101 at 70°C. The adsorption of anionic surfactant followed pseudo-second-order kinetic model. The Freundlich and Langmuir model constant were 1.6509 × 10−4 and −9.775 × 10−5, respectively. The equilibrium results showed that the adsorption of anionic surfactant onto Berea sandstone was well described by Langmuir adsorption model. It was concluded that anionic surfactants performed better at higher pH and temperature.

Study of the cloud point behavior of high oleate ester-derived nonionic surfactant

The cloud point behavior of high oleate ester-derived nonionic surfactant has been studied. The effect of various polyethoxylate chain lengths (polyethylene glycol with ethylene oxide monomer 7, 11 and 16 units) as the surfactants hydrophilic head and the effect of sodium chloride and ionic surfactants on the cloud points of nonionic surfactants synthesized were investigated. When the chain length of polyethoxylate increased, the cloud point of the synthesized nonionic surfactant also increased. Sodium chloride was found to depress the cloud point values of the formed nonionic surfactants with a linear decrease in relation to the concentration of sodium chloride used. Ionic surfactants lifted the cloud points of synthesized nonionic surfactant but in the presence of sodium chloride, the cloud point of mixed ionic-nonionic solution was suppressed.