Silicate scaling during high pH Alkaline Surfactant Polymer (ASP) flooding is known to adversely affect oil production. The silicate scale occurs as a result of the dissolution of silicates under high pH conditions and where the fluids subsequently flow into a region of lower pH where they then precipitate. The precipitation of magnesium silicate strongly depends on solution pH and temperature and is affected by the kinetics of the silicate scaling reaction. In this paper, the effect of pH on the stoichiometry and morphology of silicate scale is studied. A range of spectroscopic techniques, including Environmental Scanning Electron Microscope/ Energy Dispersive X-Ray Spectroscopy (ESEM/EDX), Fourier Transform Infrared (FTIR) and X-Ray Powder Diffraction (XRD) are applied in order to analyse the precipitated silicate scales in the laboratory. These spectroscopic techniques, when used along with reference sample spectra, yield a number of interpretive clues as to the nature of the silicate precipitates which are formed. The further analysis of the solution and precipitate by Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES) and ESEM/EDX also gave complementary information which was consistent with the results obtained from the other spectral methods above. The approach used in this work has enabled us to establish the composition and morphology of the silicate scales formed under different pH condition. There is relationship between the pH conditions and the compounds appearing in the precipitate. Results obtained can be used to help determine the most appropriate type of scale inhibitor for silicate scale mitigation in future.

Barium sulfate (barite) scale deposition may cause the problem in surface and subsurface production equipment resulting in reduced production, decrease in pressure, and premature failure of down holes equipment. One of the barite scale management is by using dissolver. There are many chelating agents that can be used to dissolve this scale including ethylenediaminetetraacetic acid (EDTA). In this work, EDTA is used to dissolve the laboratory-reproduced barium sulfate scale. Barite scale was reproduced in the laboratory by mixing barium chloride (BaCl2) solution and sodium sulfate (Na2SO4) solution at 25°C. The sensitivity analysis was performed to determine the optimum parameters/conditions in which EDTA dissolution is optimum through Inductively Coupled Plasma Optical Emission Spectrometry (ICP-EOS) analysis and characterization study using Field Emission Scanning Electron Microscope (FESEM). This includes the effect of agitation, temperature, pH, catalyst used, and the presence of oxalate ion. These laboratory tests showed that the solubility of barite increased as it was agitated; at high pH of 11 to 13; and at elevated temperature of 95°C. Potassium chloride (KCl) at high elevated temperature was used as synergy/activator to improve the dissolution of barium sulfate with EDTA. As a conclusion, this project sets a framework to identify the best EDTA formulation and estimate its dissolution profile to ensure a more informed treatment design for barite scale removal.

Polymer flood is known as the most important enhanced oil recovery technology due to its various advantageous and relatively cheaper price. However, it comes with associated problems of polymer adsorption that leads to injectivity loss. This work aims in studying various parameters that may affect the ATBS/ Acrylamide copolymer adsorption in a porous medium to optimize the polymer scheme. Synthetic D brine with D sand sample was mixed and tested in static and dynamic condition. These tests were conducted at room temperature and 90°C whereby the core flooding experiments were conducted with varied flowrate through Berea Sand Core sample. Results show that a higher brine salinity and a longer aging time leads to higher adsorption rate whereas adsorption static test conducted at replicated reservoir condition of 90°C resulted in lower adsorption capacity than at room temperature. Also, static adsorption was found to be higher than the dynamic adsorption due to the changes in the specific surface area and the extent of mechanical retention present in the dynamic core flood experiment. In conclusion, the type of polymer used in polymer flooding must be carefully chosen to serve the need for a specific reservoir condition so that the adsorption phenomenon is minimized.

Trimethylolpropane (TMP) ester is an eco-friendly lubricant that fully biodegradable and known as bio lubricant. In this study, TMP ester was produced from waste cooking oil and rubber seed oil through a two-step synthesis approach. The reaction is two stages transesterifications, in which the waste cooking oil and the rubber seed oil were first transesterified with methanol to produce methyl ester, followed by transesterification with TMP using para-Toluenesulfonic acid (p-TSA) as catalyst. Various effects of operating conditions were observed, such as reaction time, temperature and molar ratio of reactants. The TMP ester formation was determined based on the quantity of reactant conversion. The synthesized TMP ester was compared and characterized according to their properties. The results showed that the TMP ester from waste cooking oil (WCO) has shown better conversion compare to TMP ester from rubber seed oil (RSO), within a similar operating condition. The highest TMP ester conversion from WCO is 71%, at temperature of 150 ºC with molar ratio of FAME to TMP of 3:1 and catalyst amount of 2% (wt/wt). In addition, these polyol based esters from WCO and RSO exhibit appropriate basic properties for viscosity when compare with requirement standard of lubricant ISO VG46. Copyright © 2020 BCREC Group. All rights reserved

Silica/silicate scale is a significant problem, especially in oilfield production during Alkaline Surfactant Polymer (ASP) flooding, where chemical inhibitors are the preferred method to prevent them. In this study, the effect of inhibitor vinyl sulfonated copolymer (VS-Co) on silica/silicate scale formation was analysed using X-Ray Diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR).The functional group type of VS-Co are sulfonate ions, SO3-, and these interact in the scaling process. Bulk-inhibited scaling brine tests were conducted at 60C and pH 8.5. During these tests, the silicon brine (with VS-Co) representing the inhibited ASP leachate was mixed with a magnesium brine representing the connate water to replicate reservoir conditions during ASP flooding. The samples tested in this study were non-inhibited Si/Mg mixed brine of 60 ppm Mg2+ and 940 ppm Si4+ (60Mg:940Si) as a blank, and inhibited 60Mg:940Si mixture with various VS-Co concentrations of 20 ppm, 50 ppm, and 100 ppm. The inhibition efficiency of the VS-Co was determined, followed by the characterisation study of the silica/silicate scale deposited from both test conditions.The IR spectra of all 60Mg:940Si samples show a similar peak at 1050 cm-1 to 1080 cm-1, attributed to a Si-O covalent bond and a band at 790 cm-1 to 800 cm-1 showing the presence of Si-O-Si stretching. XRD patterns produced a broad scattering peak for all samples at 2 of 24 showing that the samples are amorphous silica. For tests of high Mg2+ in the brine mix, 900Mg:940Si, a mix of crystalline silica and crystalline magnesium silicate was produced. Based on these results, it can be concluded that the scale formed even with 100 ppm of VS-Co present. Further studies are required to address how to mitigate scale formation effectively in the future.Based on the research conducted, we can conclude that the VS-Co alone could not significantly inhibit the formation of silica/silicate scale even at the highest concentration (100 ppm) of VS-Co. However, having VS-Co present caused an alteration in IR spectra frequency which requires further investigation to assess how best to develop the inhibiting properties of the VS-Co product. The application of nanoparticles and their successful stories spark the interest of authors in searching for an efficient method of managing the silica/silicate scale where the modification of potential scale inhibitor (SI) with nanoparticles may be able to improve the inhibition efficiency towards the silicate/silicate scale.The presence of VS-Co in the scaling brine only slightly inhibits the Mg2+ ion (initially comes from connate water) from reacting. It is worth further investigation on how this VS-Co can make it happen. Hence, the functional groups responsible for this may be altered by adding other functional groups to provide a synergistic effect in preventing this silica/silicate scale; or by modifying the VS-Co with nanoparticles to improve their adsorption/desorption capacity.The newly developed technique in analysing the inhibition mechanism of a chemical inhibitor using various spectroscopic analysis is promising where an alteration in the spectra may provide proof of the chemicals inhibition efficiency.