Experimental Investigation of Fuel Quality and Contaminant Materials from Liquefied Petroleum Fuel

In this study, the quality characteristics and residue analysis in circulated LPG fuel were investigated experimentally in Korea. Quality characteristics in circulated LPG fuel were examined with samples of LPG in the supply chain (refinery, petrochemical, and imported LPG), transport, gas stations, and vehicles. The experimental results showed that quality of all circulated LPG was well within the quality standard guideline of LPG in Korea. Especially, it has shown average 13 wt ppm in sulfur content over the full circulated LPG. The residue samples in LPG fuel were extracted on 2 L scale with acetonitrile and analyzed by gas chromatography-mass spectrometry (GC-MS). The components of residues in LPG were composed of 62 organic chemicals with C3 ~ C28 and the main ingredients of residue were plasticizers ((di-octyl phalate (DOP), di-octyl adiphate (DOA) etc.), lubricant oil and amine compounds. It was also showed that mass of residue in vehicles was increasing compared with supply (refinery, petrochemical, and imported LPG). It was presumed that this residue had been originated from automotive LPG fuel, vehicle components, and lubricant oil in infrastructure.

Active corrosion protection of super-hydrophobic corrosion inhibitor intercalated Mg-Al layered double hydroxide coating on AZ31 magnesium alloy

Magnesium alloys,the advanced lightweight structural materials,have been successfully applied in the manufacturing field.Unfortunately,their poor corrosion resistance restrains the potential wide applications.In this work,anti-corrosion coatings were fabricated via the insitu growth of the corrosion inhibitors intercalated magnesium-aluminum layered double hydroxide(Mg-Al LDH)on AZ31 magnesium alloy and then post-sealing it by a super-hydrophobic coating.SEM,XRD,EDS,FTIR,XPS and contact angle test were conducted to analyze physical/chemical features of these coatings.Potentiodynamic polarization curves and electrochemical impedance spectroscopy were recorded to assess the anti-corrosion performance of prepared coatings.Surprisingly,Mg-Al LDH with molybdate intercalation and lauric acid modification achieves the excellent corrosion inhibition performance(99.99%)due to the multicomponent synergistic effect such as the physical protection of Mg-Al LDH,the corrosion inhibition of molybdate and super-hydrophobic properties of lauric acid.This work presents a scientific perspective and novel design philosophy to fabricate the efficient anti-corrosion coating to protect magnesium alloys and then expand their potential applications in other field.

Permeability and heterogeneity adaptability of surfactant-alternating-gas foam for recovering oil from low-permeability reservoirs

As the traditional polymer stabilizer is eliminated to improve the injectability of foam in lowpermeability reservoirs,the stability,plugging capacity,conformance control and oil recovery performance of the surfactant-alternating-gas(SAG)foam become significantly important for determining its adaptability to permeability and heterogeneity,which were focused and experimentally researched in this paper.Results show that the SAG bubbles are highly stable in micron-sized channels and porous media(than in the conventional unconstrained graduated cylinder),making it possible to use in enhanced oil recovery(EOR).Such bubbles formed in porous media could be passively adjusted to match their diameter with the size of the pore.This endows the SAG foam with underlying excellent injectability and deep migration capacity.Permeability adaptability results indicate a reduced plugging capacity,but,increased incremental oil recovery by the SAG foam with decreased permeability.This makes it a good candidate for EOR over a wide range of permeability,however,parallel core floods demonstrate that there is a limiting heterogeneity for SAG application,which is determined to be a permeability contrast of 12.0(for a reservoir containing oil of 9.9 m Pa s).Beyond this limit,the foam would become ineffective.

Long-Lasting Filtration of Oily Water by Anti-Fouling Underwater Oleophobic Sand Particles

The produced water from the oilfield was purified with filter material and then injected back into the ground.The serpentine filter material was easy to harden with the increase in filtration amount,which affected the water quality.A superhydrophilic/underwater oleophobic serpentine filter material was successfully prepared by a simple method of coating modification,which exhibited long-lasting filtration of oily water,good filtration and anti-fouling properties,and resistance to harden.The film-forming material of the superhydrophilic/underwater oleophobic coating was composed of SiO_(2) particles with small size,which could completely and evenly cover the filter particle.The weight loss was only 7.6%after mechanical stirring for 90 min.Compared with the original filter material,the superhydrophilic/underwater oleophobic serpentine filter material showed a better anti-fouling ability and resistance to harden.The filtration of crude oil emulsion and oil slick sewage showed a better backwashing performance.After 35 cycles of continuous filtration of suspended solids in wastewater,the backwashing rate reached 78.4%.The results provided an effective method for the filtration of oily wastewater in the oilfield.

Microscopic sand production simulation and visual sanding pattern description in weakly consolidated sandstone reservoirs

To visually describe the sanding pattern,this study constructs a new particle-scale microstructure model of weakly consolidated formation,and develop the corresponding methodology to simulate the sanding process and predict sand cavity shape.The microstructure model is a particle-objective model,which focuses on the random sedimentation of every sand grain.In the microstructure,every particle has its own size,sphericity and inclination angle.It is used to simulate the actual structure of cemented granular materials,which considers the heterogeneity and randomness of reservoir properties,provides the initial status for subsequent sanding simulation.With the particle detachment criteria,the microscopic simulation of sanding can be visually implemented to investigate the pattern and cavity shapes caused by sand production.The results indicate that sanding always starts initially from the borehole border,and then extends along the weakly consolidated plane,showing obvious characteristic of randomness.Three typical microscopic sanding patterns,concerning pore liquefaction,pseudo wormhole and continuous collapse,are proposed to illustrate the sanding mechanism in weakly consolidated reservoirs.The nonuniformity of sanding performance depends on the heterogeneous distribution of reservoir properties,such as rock strength and particle size.Finally,the three sanding patterns are verified by visually experimental work.The proposed integrated methodology is capable of predicting and describing the sanding cavity shape of an oil well after long-term sanding production,and providing the focus objective of future sand control measure.

A novel numerical simulation of CO_(2) immiscible flooding coupled with viscosity and starting pressure gradient modeling in ultra-low permeability reservoir

CO_(2) immiscible flooding is an environmentally-friendly and effective method to enhance oil recovery in ultra-low permeability reservoirs.A mathematical model of CO_(2) immiscible flooding was developed,considering the variation in crude oil viscosity and starting pressure gradient in ultra-low permeability reservoirs based on the non-Darcy percolation theory.The mathematical model and numerical simulator were developed in the C++language to simulate the effects of fluid viscosity,starting pressure gradient,and other physical parameters on the distribution of the oil pressure field,oil saturation field,gas saturation field,oil viscosity field,and oil production.The results showed that the formation pressure and pressure propagation velocity in CO_(2) immiscible flooding were lower than the findings without considering the starting pressure gradient.The formation oil content saturation and the crude oil formation viscosity were higher after the consideration of the starting pressure gradient.The viscosity of crude oil considering the initiation pressure gradient during the formation was higher than that without this gradient,but the yield was lower than that condition.Our novel mathematical models helped the characterization of seepage resistance,revealed the influence of fluid property changes on seepage,improved the mathematical model of oil seepage in immiscible flooding processes,and guided the improvement of crude oil recovery in immiscible flooding processes.

The Hydraulic Fracturing Optimization for Stacked Tight Gas Reservoirs Using Multilayers and Multiwells Fracturing Strategies

Based on a geology-engineering sweet spot evaluation,the high-quality reservoir zones and horizontal well landing points were determined.Subsequently,fracture propagation and production were simulated with a multilayer fracturing scenario.The optimal hydraulic fracturing strategy for themultilayer fracturing networkwas determined by introducing a vertical asymmetry factor.This strategy aimed to minimize stress shadowing effects in the vertical direction while maximizing the stimulated reservoir volume(SRV).The study found that the small vertical layer spacing of high-quality reservoirs and the presence of stress-masking layers(with a stress difference of approximately 3∼8 MPa)indicate that interlayer stress interference from multilayers and multiwells fracturing between neighboring developed formations could affect the longitudinal propagation of the reservoirs.In addition,this study investigated well spacing optimization by comparing uniformly spaced wells(100–300 m)with asymmetric spaced wells(200 m upper layer,250 m lower layer).Numerical results indicated that asymmetric spaced well placement yielded the largest stimulated reservoir volume(SRV)of 73,082 m^(3),representing a 65.42%increase compared to 100 m spaced wells.Furthermore,four different hydraulic fracturing sequences(interlayer,up-down,down-up,and center-edge)were compared for multilayer and multiwell networks.The center-edge sequence exhibited the lowest vertical asymmetry factor(0.71)and the least stress shadowing effects compared to the other sequences(0.78 for interlayer,0.75 for up-down,and 0.76 for down-up).This sequence also achieved the largest SRV(486,194m^(3)),representing an 11.87%increase compared to the down-up sequence.Therefore,the center-edge fracturing sequence is recommended formultilayer development in this block.These results offer valuable insights for optimizing well placement and fracturing sequence design in multilayer well networks,ultimately advancing the development of multilayer fracturing technology in the region.