Two aspects are always considered in the design and development of new surfactants for oilfield application. One of them is that surfactant must be sufficiently stable at reservoir temperature and the other is the solubility of the surfactant in the injection water (usually seawater) and the formation brine. Most industrially applied surfactants undergo hydrolysis at elevated temperature and the presence of reservoir ions causes surfactant precipitation. In relevance to this, a novel series of quaternary ammonium gemini surfactants with different length of spacer group (C8, C10, and C12) was synthesized and characterized using FT-IR, 13C NMR, 1H NMR, and MALDI-TOF MS. The gemini surfactants were prepared by solvent-free amidation of glycolic acid ethoxylate lauryl ether with 3-(dimethylamino)-1-propylamine followed by reaction with dibromoalkane to obtain quaternary ammonium gemini surfactants. The gemini surfactants were examined by means of surface properties and thermal stabilities. The synthesized gemini surfactants showed excellent solubility in the formation brine, seawater, and deionized water without any precipitation for up to three months at 90 °C. Thermal gravimetric data revealed that all the gemini surfactants were decomposed above 227 °C, which is higher than the oilfield temperature (≥90 °C). The decrease in critical micelle concentration (CMC) and surface tension at CMC (γcmc) was detected by enhancing spacer length in the order C8 ˃ C10 ˃ C12 which suggested that the larger the spacer, the better the surface properties. Moreover, a further decrease in CMC and γcmc was noticed by enhancing temperature (30 °C ˃ 60 °C) and salinity (deionized water ˃ seawater). The current study provides a comprehensive investigation of quaternary ammonium gemini surfactants that can be further extended potentially to use as a suitable material for oilfield application.
This study offered a detailed review of data sciences and machine learning (ML) roles in different petroleum engineering and geosciences segments such as petroleum exploration, reservoir characterization, oil well drilling, production, and well stimulation, emphasizing the newly emerging field of unconventional reservoirs. The future of data science and ML in the oil and gas industry, highlighting what is required from ML for better prediction, is also discussed. This study also provides a comprehensive comparison of different ML techniques used in the oil and gas industry. With the arrival of powerful computers, advanced ML algorithms, and extensive data generation from different industry tools, we see a bright future in developing solutions to the complex problems in the oil and gas industry that were previously beyond the grip of analytical solutions or numerical simulation. ML tools can incorporate every detail in the log data and every information connected to the target data. Despite their limitations, they are not constrained by limiting assumptions of analytical solutions or by particular data and/or power processing requirements of numerical simulators. This detailed and comprehensive study can serve as an exclusive reference for ML applications in the industry. Based on the review conducted, it was found that ML techniques offer a great potential in solving problems in almost all areas of the oil and gas industry involving prediction, classification, and clustering. With the generation of huge data in everyday oil and gas industry activates, machine learning and big data handling techniques are becoming a necessity toward a more efficient industry.
Shale
swelling during drilling operations causes many problems
mainly related to wellbore instability. The oil-based muds (OBMs)
are very effective in controlling the swelling potential of clay-rich
shale formation, but their environmental concerns and the economic
aspects curtail their usage. In the application of water-based mud
(WBM), it is mixed with various swelling inhibitors such as inorganic
salts (KCl and NaCl), sodium silicate, polymers, and amines of various
types. The above-mentioned materials are however afflicted by some
limitations in terms of their toxicity, their effect on drilling mud
rheology, and their limited tolerance toward temperature and oil contamination.
In this study, we investigated a novel hybrid aqueous alkali alumino
silicate (AAAS) as a shale swelling inhibitor in WBM. The AAAS is
a mixture of sodium, aluminum, and silicon oxides. Experimental investigations
were carried out using a linear swell meter, hot rolling and capillary
suction timer, ζ-potential test, filtration test, and rheology
test. The application of hybrid silicate as a swelling inhibitor was
studied in two phases. In the first phase, only silicate solutions
were prepared in deionized water at various ratios (1, 2, and 5%)
and tested on sodium bentonite and shale samples containing high contents
of kaolinite clay. Further testing on commonly used inhibitors such
as KCl and sodium silicate solutions was conducted for comparative
purposes. In the second phase, different drilling mud formulations
consisting of various percentages of AAAS were mixed and tested on
original shale samples. It was observed that the novel silicate-based
mix proved to be a strong shale swelling inhibitor. Its inhibition
performance was better as compared to the sodium silicate solution
and KCl solution. It not only inhibits shale swelling but also acts
as a shale stabilizer due to its high adsorption on the shale surface,
which prevents the shale/water reactivity, makes the shale formation
stronger, and prevents caving.
Clay
swelling is one of the challenges faced by the oil industry.
Water-based drilling fluids (WBDF) are commonly used in drilling operations.
The selection of WBDF depends on its performance to improve rheology,
hydration properties, and fluid loss control. However, WBDF may result
in clay swelling in shale formations during drilling. In this work,
the impact of imidazolium-based ionic liquids on the clay swelling
was investigated. The studied ionic liquids have a common cation group,
1-allyl-3-methyllimidozium, but differ in anions (bromide, iodide,
chloride, and dicyanamide). The inhibition behavior of ionic liquids
was assessed by linear swell test, inhibition test, capillary suction
test, rheology, filtration, contact angle measurement, scanning electron
microscopy, and X-ray diffraction (XRD). It was observed that the
ionic liquids with different anions reduced the clay swelling. Ionic
liquids having a dicyanamide anion showed slightly better swelling
inhibition performance compared to other inhibitors. Scanning electron
microscopy images showed the water tendency to damage the clay structure,
displaying asymmetrical cavities and sharp edges. Nevertheless, the
addition of an ionic liquid to sodium bentonite (clay) exhibited fewer
cavities and a smooth and dense surface. XRD results showed the increase
in d-spacing, demonstrating the intercalation of ionic liquids in
interlayers of clay. The results showed that the clay swelling does
not strongly depend on the type of anion in imidazolium-based ILs.
However, the type of anion in imidazolium-based ILs influences the
rheological properties. The performance of ionic liquids was compared
with that of the commonly used clay inhibitor (sodium silicate) in
the oil and gas industry. ILs showed improved performance compared
to sodium silicate. The studied ionic liquids can be an attractive
alternative for commercial clay inhibitors as their impact on the
other properties of the drilling fluids was less compared to commercial
inhibitors.
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