Performance evaluation of nanosilica derived from agro-waste as lost circulation agent in water-based mud

Seepage or loss of the mix-water from the drilling muds into the porous and permeable formations is a common problem during drilling operation.The drilling mud design requires a good knowledge of sealing integrity and all the factors influencing the mud to bridge through fractures or pore throat of exposed rocks.Loss circulation materials(LCMs)are commonly introduced into the drilling mud to prevent or minimize filtrate loss.This study investigates silica nanoparticle(SNP)derived from rice husk(RH)termed RH-SNP using the wet-milling method as an LCM inwater-based mud(WBM).The impact of the RH-SNP in the enhancement of rheology and filtrate loss control properties of WBM was studied.Subsequently,the sealing integrity of the RH-SNP in a 1 mm and 2 mm simulated fracture for 7 min was determined using a stainless-steel slotted filter disk.The performance of the developed RH-SNP was compared with the widely applied nutshell.The synthesized RH-SNP at amount of 2.0 wt% significantly enhanced the yield point and plastic viscosity of the WBM by 75% and 386%,respectively,and minimized the fluid loss of the WBM by 47% at 80°F.The enhancement is due to the particles ability to spread and interact efficiently with the WBM.With the use of 1 mm and 2 mm simulated fracture for 7 min,the mud loss volume of the base mud reduced by 50%,66.7%,86%,and 90%(for 1 mm)and 40%,65.7%,77.1%,and 80%(for 2 mm)with the inclusion of 0.5 wt%,1.0 wt%,1.5 wt%,and 2.0 wt% of RH-SNP,respectively.Overall,the results showed that RH-SNP enhanced the seal integrity of the drilling mud and was more resistant to deformation compared to the nutshell.The findings of this study can help for better understanding of the application of RH-SNP as a loss circulation agent owing to its superior ability to seal fractured formation compared with the often used nutshell.

Oil-water interfacial tension, wettability alteration and foaming studies of natural surfactant extracted from Vernonia Amygdalina

Surfactant flooding is an enhanced oil recovery(EOR)method for recovering residual oil in the reservoir through mechanism of interfacial tension(IFT)reduction and wettability alteration.Due to toxicity and high cost associated with conventional surfactants,recent research has focussed on developing low-cost and environmentally benign surfactants.Herein,a low-cost green surfactant is extracted from Vernonia Amygdalina(VA)and appraised for EOR applications.The extracted surfactant was characterized using Fourier Transform Infrared(FTIR)and High-Pressure Liquid Chromatography(HPLC).The IFT of the synthesized surfactant at the oil-water interface was determined using Kruss tensiometer.Additionally,the foam stability of the synthesized surfactant was examined.Moreover,the wettability of the saponin based natural surfactant(SBNS)at the rock-fluid interface was analysed using Dataphysics drop shape analyser.Experimental result revealed that SBNS(1 wt%concentration)stabilized foam for longer periods with half-life of 1100 min.Furthermore,the synthesized surfactant was effective in lowering the IFT of oil-water interface from 18 mN/m to 0.97 mN/m.Finally,SBNS altered the wettability of sandstone cores to water-wetting condition by reducing the contact angle from 118.5° to 45.7°.Overall,SBNS exhibit excellent properties desirable for EOR and thereby recommended as supplementary alternative to conventional surfactants.

The effect of nanosilica sizes in the presence of nonionic TX100 surfactant on CO_(2)foam flooding

The aim of this research is to study the effect of hydrophilic silica nanoparticles,sizes as CO_(2) foam stabilizer in the presence of nonionic TX100 surfactant.Two nanosilica sizes,15 and 70 nm,have been examined thoroughly.Physisorption of TX100 on silica nanoparticles(nanosilica)was characterized by adsorption isotherm and surface tension measurement,while CO_(2) foams stability was quantified based on their foamability,foam stability,particle partitioning in the foams,and bubble sizes.Results show that direct contact of TX100 with nanosilica does altered the wettability of hydrophilic nanosilica surface,enable them to lengthen CO_(2) foams life at certain surfactant and nanoparticles concentrations.For 15 nm nanosilica,CO_(2) foam stability shows excellent performance at 0.1 and 0.5 wt%TX100 concentrations.As for 70 nm nanosilica,CO_(2) foam demonstrates longer lifetime at much lower TX100 concentration,0.01 wt%.Without the presence of TX100,CO_(2) foams exhibit undesirable lifetime performances for both nanosilica sizes.Nanosilica partitioning in CO_(2) foams structures demonstrate consistent relation with contact angle measurement.Estimated bubble sizes shows insignificant effect on CO_(2) foams life.With the assists of nanosilica and TX100,enhanced oil recovery via CO_(2) foam injection succeeds in increasing oil production by 13e22%of original oil-in-place(OOIP).

Intermittent and short duration ultrasound in a simulated porous medium

Ultrasound is an unconventional method used to recovery oil,despite the report on the use of this technique,the focus has always been on the continuous application of ultrasound.But the continuous ultrasound has its own limitation of high cost of production and maintenance of equipment because of high energy generated.In this study,the use of short duration,intermittent ultrasound was investigated,and the result compared with the continuous ultrasound.The effect of viscosity and intensity on both intermittent and continuous ultrasound was also investigated.A 2D micro-model placed inside an ultrasonic bath under an ultrasound radiation was used,a stereo microscope with the camera mounted at the top of the micro-model recorded the displacement process.The snapshot of each time interval was used to give the estimate in percentage(%)of the residual oil left in the micro-model.The results show that,short duration and intermittent ultrasound can recover more oil compared with the application using continuous ultrasound and longer duration.Therefore,the use of intermittent ultrasound as a green and cost-effective technique is herein proposed.

Screening the synergy of sodium dodecylbenzenesulfonate and carboxymethyl cellulose for surfactant-polymer flooding

Carboxymethyl cellulose(CMC)has emerged in oil and gas industries as a superior substitution to the conventional HPAM and xanthan gum(XG)for high viscosity polymer flooding application.In this study,the combined effect of conventional surfactant,sodium dodecylbenzenesulfonate(SDBS)and CMC for potential surfactant-polymer(SP)flooding in enhanced oil recovery(EOR)has been investigated.Thereafter,SDBS–CMC interaction and the functional groups present in CMC were appropriately identified.The presence of various C–O bonds signifies the existence of carboxymethyl group which greatly influence the rheological properties of CMC solution.The behaviour of SDBS–CMC was characterized by their viscosity,shear rate,solubilization,wettability,and surface tension.Tertiary flooding utilizing SDBS-CMC was performed and compared to commercial SDBS-XG SP flooding.The results indicate several SDBS-CMC combinations are favourable for EOR application.Solution viscosity shows direct relationship with CMC concentrations.Consequently,at any given SDBS concentrations,significant increment was observed at 0.3 wt%and above.However,the trend displayed inconclusive relation to SDBS fractions.Majority of the SDBS-CMC combinations generate Winsor III emulsions particularly at CMC of 0.2 and 0.3 wt%,while Type II were observed in few combinations.Increasing CMC concentrations increased the contact angle,while gradual reductions were observed with SDBS concentrations.The gradual reduction in surface tension was highly influenced by the addition of CMC rather than SDBS.A novel combination of 0.3 wt%SDBS and 0.4 wt%CMC possessed an encouraging criterion in term of viscosity,solubilization,and surface tension reduction for EOR application.Flooding experiment from several SDBS-CMC combinations proved to recover additional oil ranging 16.4–20.2%of oil initially in place(OIIP).The trend in incremental oil recovery is similar to that of when utilising SDBS-XG.

Pore volumes to breakthrough estimation in carbonate acidizing with hydrochloric acid by using an analytical derivation method

Acidizing treatment is considered as a significant process in the oil well stimulations to form wormholes in carbonate formation in order to enhance the reservoir fluid production.Obtaining the number of pore volumes to breakthrough is an important objective in matrix acidizing,for it contributes to determining the wormhole characteristics such as type,shape,and size.Finding this number in experimental works requires a considerable amount of time,energy and cost.Therefore,this study aimed to establish an analytical method in which a reasonable result is achieved for the number of pore volumes to breakthrough.This purpose is accomplished by solely implementing acid and formation properties without performing any experimental works.The process of wormhole creation is done through developing a numerical model by utilizing the conservation of mass law method in which the carbonate core is considered as a closed system and the overall mass in the system as constant during the acid injection process.Furthermore,a constant number is added to the mathematical part of the model in order to eliminate the dimensionless Damk鰄ler number which is supposed to be calculated experimentally.The results of the numerical procedure of the model are further compared to four other experimental works,which led to calculating the average accuracy of this model that is shown to be 95.98%.This study puts forward a comprehensive numerical model to estimate the number of pore volumes to breakthrough with an acceptable accuracy rate merely through implementing known acid and core properties.

Estimation of pore volumes to breakthrough number in limestone cores by derivation of an empirical model

Acidizing in carbonate formations is an inevitable stimulation treatment method for oil and gas wells.In the limestone,acidizing stimulation makes capillary wormholes to increase fluids flow reservoir production.The pore volume to breakthrough number is one of the main indexes for recognizing the wormhole structure.Therefore,finding the pore volume to breakthrough number is one of the main goals in the limestone acidizing.Obtaining this number is always required for experimental works,which needs time,energy and cost.The purpose of this research is to develop an empirical method to estimate an acceptable result for this number merely by implementing limestone core and acid properties without any experimental work.In order to create a wormhole,an empirical method is developed using the law of conservation of mass considering that the core of limestone as an isolated package and the overall mass is constant in this package in the acidizing period.Also,to develop the mathematical section,the Damk€ohler number is used.Since this number must be calculated experimentally,a constant number is created in the model to eliminate the Damkohler number.An average accuracy of 92.31%is obtained for the developed empirical model by comparing the results obtained from the other three experimental and numerical works.This study conclusively provides a thoroughly empirical method for estimating a high accuracy of the pore volume to breakthrough number by only using known physical properties limestone core and acid.