Colloidal Gas Aphrons: A Novel Approach to Preventing Formation Impairment

Colloidal gas aphrons (CGAs) were first reported by Sebba (1971) as micro bubbles (25-125 μm), composed of a gas nucleus surrounded by a thin surfactant film and created by intense stirring of a surfactant solution. Since then, these colloidal dispersions have been used for diverse applications, with a particular focus on separation processes. However, exploitation of CGAs in petroleum industry is only at the outset. CGAs were first used in west Texas in 1998, under the name Aphron drilling fluids. This kind of fluid is characterized as having a continuous phase, a high viscosity at a low shear rate and containing, as an internal phase, micro air or gas bubbles, non-coalescing and recirculating. In this paper, we illuminate the physical and chemical properties of aphron drilling fluid and its processing mechanism.

Separation of Fine Particles by Using Colloidal Gas Aphrons

This paper presents a method of separation of fine particles, of the order of a few microns or less, from aqueous media by flotation using colloidal gas aphrons (CGAs) generated in aqueous solutions. More than 150 experiments were conducted to study the effects of surfactant type, surfactant concentration, CGAs flow rate, and particle concentration on the removal efficiency (fine particles of polystyrene were used as a target compound). The results indicate that CGAs, generated from cationic surfactant of hexdecyltrimethyl ammonicum bromide (HTAB) and anionic surfactant of sodium dodecylbenzne sulfonate (SDBS), are an effective method for the separation off ine particles of polystyrene from wastewater. The flotation yields are higher than 97%.

Kinetic Rate Constant of Liquid Drainage from Colloidal Gas Aphrons

A kinetic model fitted by the empirical equation has been proposed to describe the liquid drainage behavior. Rate constants （kd） of liquid drainage equation could be obtained from the above empirical equation. In this paper, the stability of the colloidal gas aphrons （CGAs）, the effect of concentrations of sodium dodecyl benzene sulphate （SDBS）, dodecyl trimethylammonium bromide （HTAB） and polyoxyethylene sorbitol anhydride monolaurate（Tween-20）, temperature, stirring speed, stirring time, and various kinds of salts on the kd of liquid drainage are further investigated. The results show that the Arrhenius equation can be successfully used to describe the relation between kd arid absolute temperature （T）, and concentrations of surfactants, stirring speed, stirring time and salinities also have great effect on the kd. At last, the CGAs drainage mechanism is explained from analysis of the rate of liquid drainage as a function of time.

Separation of Organic Dyes from Water by Colloidal Gas Aphrons

Colloidal gas aphrons (CGAs) are micron sized gas bubbles produced by stirring surfactant solutions at high speed. A single CGA dispersed in water is composed of a gaseous inner core, surrounded by a double water soapy layer. CGAs have large interfacial area per unit volume and exhibit relatively high stability. These characteristics make CGAs very suitable in flotation systems. This paper studied the flotation of organic dyes from water using CGAs. The experimental results show that the flotation process may follow four mechanisms, i.e., ion coupling of the oppositely charged species of the surfactant forming the CGA and the organic dye, reactions between CGA and the organic dye, ion dye complex adsorbed on the surface of CGAs, and hydrophilic or hydrophobic characteristics of the organic dyes.

微泡沫钻井液Aphron最新进展

美国ActiSystems公司研制了一种全新的、在近平衡钻井中使用的"微泡"钻井液,又称为"Aphrons"钻井液。它是一种钻进易漏地层时控制漏失的特殊钻井液,它由特定的表面活性剂和聚合物组成,形成一种微泡体系或Aphrons体系,即非聚集、可循环使用的均匀刚性气核体系,这些微泡或Aphrons包裹在一种独特的增粘体系中。微泡体系吸引人的特征主要是它不需要空气或泡沫钻井中使用的额外设备,也不需要增加成本和涉及安全的压缩机、高压水龙带以及连接装置,该钻井液体系使用常规的钻井液混合设备就可获得抗压性能好、可变形的微泡。它在使用时不仅可以实现钻井液密度的还原,还能阻止或延缓钻井液进入地层,建立起一个真正的非侵入的、近平衡的环境,是钻定向井和水平井的理想钻井液。

PREDISPERSED SOLVENT EXTRACTION──THE STATE-OF-THE-ART REVIEW

Predispersed solvent extraction (PDSE) is a new extraction technique in which one of the two phases (usually the oil phase) is predispersed into minute droplets. The essential part of this novel technique is the use of colloidal liquid aphrons (CLA) together with colloidal gas aphrons (CGA). The use of colloidal liquid aphrons in predispersed solvent extraction may ameliorate the problems such as emulsion formation, reduction of interfacial mass transfer etc. In this paper, PDSE process, CLA and CGA are systematically reviewed and the potential applications of CLA, CGA and PDSE for the various areas of separation as well as the latest development in this area are discussed.

Aphron钻井液体系在大牛地气田的应用前景

大牛地气田为典型低孔低渗砂岩气藏,不易形成自然产能,勘探开发中选择合适的钻井液体系保护储层显得格外重要,但目前该气田所使用的钻井液体系均没有取得令人满意的储层保护效果。近年来,针对低孔低渗砂岩储层保护的新型钻井液技术—Aphron钻井液技术得到了不断发展与完善,并在美国的Fusselman油田得到推广应用。本文据该钻井液技术的相关特性及大牛地气田储层特征分析,得出Aphron钻井液体系在大牛地气田具有相当广阔的应用前景。

Insight into selection of appropriate formulation for colloidal gas aphron(CGA)-based drilling fluids

Application of light-weight drilling fluids is essential to develop depleted hydrocarbon reservoirs.Recently,colloidal gas aphron(CGA)-based fluids have been introduced for such applications due to their ability in controlling fluid losses.In this work,a comprehensive experimental study was performed to choose the best formulation for CGA fluids by implementing static stability tests,rheological behavior measurements,and bubble size analyses of CGAs.Xanthan gum polymer and sodium dodecyl benzene sulfonate(SDBS),an anionic surfactant,and cetyl trimethyl ammonium bromide(CTAB),a cationic surfactant,were utilized to prepare CGAs.For the range of experiments conducted,the performance of CGA fluids prepared with SDBS was improved by increasing the polymer and surfactant concentrations.However,for CTAB,it was improved by an increase in the polymer concentration and a decrease in the surfactant concentration.The formation of white,long hair-like precipitates observed at high levels of CTAB caused CGA fluid to become rapidly unstable.Also,it was observed that the size of CGAs was significantly influenced by the polymer and surfactant concentrations.The most stable bubbles were formed at 6.86 g/L of polymer concentration.The results of this study provide insights into appropriate formulation for CGA-based fluids which could be potentially applicable in drilling operations.

Removal of Phenol from Dilute Solutions by Predispersed Solvent Extraction

Predispersed solvent extraction (PDSE) is a new method for separating solutes from aqueous solution by solvent extraction and one which has shown promise for extraction from extremely dilute solution very efficient and very quick. The use of colloidal liquid aphrons in predispersed solvent extraction may ameliorate the problems such as emulsion formation, reduction of interfacial mass transfer and low interfacial mass transfer areas in solvent extraction process. In present paper, colloidal liquid aphrons are successfully generated using kerosene as a solvent, tributyl phosphate(TBP) as an extractant, sodium dodecyl benzene sulphate(SDBS) as surfactant in aqueous phase and Tween-80 in oil phase. Extraction of phenol from dilute solution was studied by using colloidal liquid aphrons and colloidal gas aphrons in a semi-batch extraction column. It has been found that the PDSE process is more suitable for extraction of dilute solutions. It has also been discovered that the PDSE process has a great advantage over traditional single-stage extraction process.

Separation of Quercentin by Pre-dispersed Solvent Extraction

Pre-dispersed solvent extraction (PDSE) was used to extract quercentin from its diluted solution. The influences of temperature, phase volume ratio (PVR), concentration of sodium Dodecyl benzene sulphonate and pH value etc. on the extraction efficiency were examined. It is found that, compared with traditional extraction techniques under the same condition, a higher extraction productivity can be obtained by PDSE. The stability of colloidal liquid aphrons plays an important role in this process. In a certain scope, the extraction efficiency increases with PVR. Excessive amount of solvent is not much helpful. A new analytical method by using ultraviolet spectrometer to determine the concentration of quercentin is established.

Aphron钻井液在苏里格气田的应用前景

苏里格气田是我国主要含气盆地中的一种主要气田类型,具有低渗、低丰度、强非均质性等特征,在钻井过程中很容易受到污染和损害。随着科技的进步,在低渗砂岩储层开发方面,水平井已经广泛的应用于低渗透油气藏开采,苏里格气田在水平井施工中,遇到了地层坍塌、漏失、储层保护等难点。近年来,针对低孔低渗砂岩储层保护的Aphron钻井液技术得到了不断发展与完善,并在国外很多油田得到推广应用。本文据该钻井液技术的相关特性及苏里格气田地质特征和水平井施工难点分析,得出Aphron钻井液体系在苏里格气田具有相当广阔的应用前景。

Colloidal gas aphron(CGA) based foam cement system

To solve the problems such as high denstiy,foam instability,low compressive strength,high porosity and poor durability associated with conventional foam cements,a novel colloidal gas aphron(CGA)based foam cement system was investigated and tested for properties.CGA is used in a base slurry as the foam component and the recipe was optimized with hollow sphere and micro-silica in terms of particle size distribution(PSD).Porosity,permeability,strength,brittleness,elasticity,free water content,foam stability and density tests on the CGA based foam cement system were carried out to evaluate the performance of the system.According to the experiment results,at the foam proportion of 10%,the cement density was reduced to 1040 kg/m3,and stable microfoam net structure not significantly affected by high temperature and high pressure was formed in the cement system.The optimal CGA based foam cement has a free water content of 0%,porosity of 24%,permeability of 0.7×10-3μm2,low elasticity modulus,high Poisson’s ratio,and reasonable compressive strength,and is more elastic and flexible with capability to tolerate regional stresses.

Experimental investigation of the impact of sugarcane molasses on the properties of colloidal gas aphron(CGA)drilling fluid

Colloidal gas aphron(CGA)based fluid has become very popular in drilling in the last two decades,as it reduces formation damages significantly.In this study,sugarcane molasses(Mls)was used for the first time as a polymer in CGA-based to investigate its ability to improve the role of aphronized fluid as a drilling fluid.The results showed that increasing the concentration of Mls to 12%(v/v)in CGA-based fluid reduces the drainage rate and increases half-life to 10.6 min,resulting in enhanced stability of the aphronized fluid.Also,because of increasing Mls concentration from 1%to 12%(v/v),the yield and the initial gas hold-up decrease to 74%and 299.4 mL,respectively,indicating that the presence of Mls allows less air into the aphron system.Although the rheological properties were improved in this study,the gel strength did not change considerably.Furthermore,the results showed that by increasing the concentration of Mls,the average size of the bubbles decreases,and the particle-size distribution becomes more uniform.Finally,the API filtration test revealed that the higher the Mls concentration in the aphronized fluid,the lower the fluid loss,and at the Mls concentration of 12%(v/v),the fluid loss was estimated at 19.54 mL.A natural polysaccharide with high molecular weight,Mls can be used as a polymer in CGAbased fluid and,thus,improve its performance.

Aphron钻井液作用机理研究

Aphron钻井液是一种具有高剪切稀释性的水基钻井液,它含有一种稳定的充气泡沫(Aphrons),已在世界范围内成功地应用于衰竭产层和其他高渗透性地层的钻进。该钻井液能封堵漏层且几乎不会对地层造成永久伤害。一方面,Aphrons在岩石孔隙网络内形成一层内封堵层,能有效降低钻井液的侵入速度;另一方面,Aphrons在产液采出过程中很容易去除,对地层造成的伤害很小,同时也大大减少了洗井作业。

Aphron钻井液研究新进展

Aphron钻井液正在全世界范围内应用于衰竭储层和其他低压地层的钻进。这类钻井液的主要特点是其独特的低剪切流变性和Aphrons的存在。近来由美国能源部赞助的一项研究对该钻井液的作用原理进行了深入研究,测定了钻井液中Aphrons和其他组分的物理化学性质以及在钻进渗透性和裂缝性地层时它们对钻井液流动性能的影响,所测性能包括润湿性、表面张力、泡沫稳定性、径向动态流动可视化以及流体驱替实验。该研究的一个重要发现是Aphrons能承受至少4000lb/in2(G)的压力,高压下稳定性强,并能有效封堵漏层,阻止流体侵入;另一个重要发现是,Aphrons之间以及Aphrons与孔隙或裂缝处的岩石矿物表面之间的亲和力很小,使得Aphrons在采油生产过程中很容易被除去。该研究为Aphron钻井液的成功研制提供了技术基础,同时也为该钻井液的现场应用及其性能优化提供了技术指导。