Experimental investigation into L-Arg and L-Cys eco-friendly surfactants in enhanced oil recovery by considering IFT reduction and wettability alteration

Surfactant flooding is an important technique used to improve oil recovery from mature oil reservoirs due to minimizing the interfacial tension(IFT)between oil and water and/or altering the rock wettability toward water-wet using various surfactant agents including cationic,anionic,non-ionic,and amphoteric varieties.In this study,two amino-acid based surfactants,named lauroyl arginine(L-Arg)and lauroyl cysteine(L-Cys),were synthesized and used to reduce the IFT of oil–water systems and alter the wettability of carbonate rocks,thus improving oil recovery from oil-wet carbonate reservoirs.The synthesized surfactants were characterized using Fourier transform infrared spectroscopy and nuclear magnetic resonance analyses,and the critical micelle concentration(CMC)of surfactant solutions was determined using conductivity,pH,and turbidity techniques.Experimental results showed that the CMCs of L-Arg and L-Cys solutions were 2000 and 4500 ppm,respectively.It was found that using L-Arg and L-Cys solutions at their CMCs,the IFT and contact angle were reduced from 34.5 to 18.0 and15.4 mN/m,and from 144°to 78°and 75°,respectively.Thus,the L-Arg and L-Cys solutions enabled approximately 11.9%and 8.9%additional recovery of OOIP(original oil in place).It was identified that both amino-acid surfactants can be used to improve oil recovery due to their desirable effects on the EOR mechanisms at their CMC ranges.

Study of Water Treatment Residue Used as a Profile Control Agent

A large amount of residue from the water treatment process has gradually accumulated and thus caused serious environmental pollution in waterflood oilfields. The water treatment residue is a grey suspension, with a density of 1.08 g/cm^3, and mainly contains over 65% of light CaCO3, MgCO3, CaSO4, Fe2S3 and Ca（OH）2. This paper ascertains the effect of water treatment residue on core permeability and its application in oilfields. Coreflooding tests in laboratory were conducted in two artificial cores and one natural core. Core changes were evaluated by cast model image analysis, mercury injection method and scanning electron microscopy （SEM）. Fresh water was injected into another natural core, which was plugged with water treatment residue, to determine the effective life. The results indicate that the water treatment residue has a strongly plugging capability, a resistance to erosion and a long effective life, and thus it can be used as a cheap raw material for profile control. In the past 8 years, a total of 60,164 m^3 of water treatment residue has been used for profile control of 151 well treatments, with a success ratio of 98% and an effective ratio of 83.2%. In the field tests, the profile control agent increased both starting pressure and injection pressure of injectors, and decreased the apparent water injectivity coefficient, significantly improving intake profiles and lengthening average service life of injectors. 28,381 tons of additional oil were recovered from these corresponding oil wells, with economic benefits of ￥3,069.55×10^4 （RMB） and a remarkable input-output ratio of 8.6：1.

Lessons learned from coreflood experiments with surfactant-polymer and alkali-surfactant-polymer for enhanced oil recovery

A review of coreflood experiments for chemically enhanced oil recovery(EOR)is presented in this paper,particularly surfactant-polymer(SP)and alkali-surfactant-polymer(ASP)processes.The objective of this review is to gain a general outlook and insight from coreflood experiments injecting SP or ASP slug as tertiary recovery.The discussion is separated into sections based on relevant core and fluid properties as well as surfactant selection and SP/ASP slug design and their impact on incremental recovery.Most studies in this review have been published within the last twenty years but few older coreflood works have been included for benchmarking.Parameters in each reviewed study have been summarized in tables to help readers gain detailed observation.Lessons learned from these past experiments should help other chemical EOR practitioners or students of the field in benchmarking or improving the outcomes of their future SP/ASP experiments.

Effects of graphene oxide/TiO_(2) nanocomposite,graphene oxide nanosheets and Cedr extraction solution on IFT reduction and ultimate oil recovery from a carbonate rock

Increasing the number of depleted reservoirs and global demand for energy have left us with low alternative but to use new ways to extract more hydrocarbon.Amongst different material used for tertiary oil recovery,surfactant injection has proved very promising solutions,such as interfacial tension reduction and wettability alteration.Without any harm to the environment and meanwhile being economically feasible,natural surfactants have been attracted researchers in recent years.Cedr extraction which is produced from Zizyphus Spina Christi leaves has shown some beneficial characteristics like IFT reduction and wettability alteration.However,the amount of IFT reduction is not considerable,so we decided to augment its effectiveness by adding two different nanoparticles.In this investigation,three concentrations(0.01,0.05 and 0.1 wt%)of both graphene oxide(GO)nanosheet and GO/TiO_(2) nanocomposite was added to Cedr extraction solution to study their potential on IFT reduction and improving the ultimate oil recovery.The concentration of 0.05 wt percent showed the lowest IFT in both solutions.At this concentration,the IFT of GO/TiO_(2)-augmented solution and GO-augmented solution were measured of 10.5 and 12.3 mN/m,respectively.While the bare Cedr solution showed 23.8 mN/m at its critical micelle concentration.The coreflooding tests were also performed at the aforementioned concentrations.Final oil recovery reached to 65%of original oil volume in GO/TiO_(2)-augmented solution,compared to 56% in GO-augmented solution case and 40%in bare Cedr solution case.Scanning Electron Microscopy images were also taken from the rock samples exposed to nanofluids to investigate any severe harm to the permeability.Images showed low tendency of both particles to adsorb on rock surface and plug large pores.

The effect of type waves on vibroseismic implementation of changes properties of rock, oil viscosity, oil compound composition, and enhanced oil recovery

Based on the results of laboratory studies,the frequency of 35 Hz in longitudinal waves and 20 Hz in circular waves is the optimum frequency that can increase the maximum oil recovery.Coreflooding test results before the vibration effect can increase oil production by 51.96%and reduce the residual oil saturation by 59.03%The surprising results when the vibration effect was applied to the coreflooding test method with P wave types continuously succeeded in increasing oil production by 60.54%,inter-mittent P waves by 63.53%and circular waves by 64.76%,while also reducing Sor by 48.49%in continuous P waves,intermittent P waves at 44.81%and C waves at 43.3%,The P wave type vibrational method has an increase in oil gain by 16%,intemittently by 22%,Sor reduction by 18%and 24%,in circular wave oil gain increases by 25%,and Sor decreases by 27%from before the vibration effect given.Besides vibration can change the physical properties of rocks,among others;permeability has increased by 7%using P waves continuously,intermittently by 31%and C waves by 4%;porosity of 5.88%with P waves contin-uously,intermittently of 6.46%and circular waves of 4.63%;grain size before vibration of 45.16 um after vibration using continuous P waves of 42.01μum,intermittently of 4798μum,and circular of 50.46μum;changes in oil composition to contain more alkanes,and lack of aromatic compounds;oil viscosity increased by 3%with continuous P waves,intermittent of 5%,and circular 61%.The new point from this paper is analyzing the vibroseismic effect by using SEM images in terms of the watershed segmentation of the Rabbani algorithm compared to lab results,which have an error rate of under 2%,and a review of oil composition by the GC-MS method.