Oil-soluble Materials Research Articles

A self-breaking supramolecular plugging system as lost circulation material in oilfield

AbstractLost circulation is a frequently encountered problem during workover operations of a low-pressure reservoir. Many lost circulation materials (LCM) have been used to solve the problem, but various disadvantages still exist, for example, oil-soluble materials are easy to get stuck in the pipe string as the temperature drops and gel time and gel strength of the cross-linking gel systems are difficult to control in the occasion of inadequate stirring. A self-breaking supramolecular plugging system used to control lost circulation of workover operations is developed, and it can encounter the aforementioned disadvantages of the traditional LCM. The system forms a space grid structure by non-covalent bonds between the molecules without adding a cross-linking agent. Sand beds plugged with the supramolecular plugging system had a pressure bearing capacity of 4.5 MPa. The self-breaking rate of the supramolecular system was 100% after 7 days at a temperature of 120°C. The core permeability recovery of the self-breaking liquid was 91.9%, indicated that the plugging system is compatible of the reservoir. The supramolecular plugging system has been used in four wells in the Jidong oilfield of East China. Field practice showed that the supramolecular LCM can effectively control lost circulation at different rates during workover operations. The increase in the daily fluid after operations indicated that the slurry has not damaged the reservoir.

Experimental study of hydraulic fracture initiation and propagation in unconsolidated sand with the injection of temporary plugging agent

High fluid leak-off rate and low pressurization rate are great challenges for hydraulic fracturing in unconsolidated sands. In this paper, the design of an injection plugging agent as a pad for fracture initiation aid in unconsolidated sands is presented. We have carried out tri-axial hydraulic fracturing tests, focusing on super-high- and high-permeability unconsolidated sands with AE (acoustic emission) monitoring. Powdered oil-soluble materials are used as temporary plugging agents. The laboratory tests demonstrated that three types of fracture geometry, multiple fracture, bi-wing fracture and single-wing fracture, are created. Furthermore, there are continuous AE energy signals with the increase of plugging agent injection, which is a good match with the fluctuated pressure. Moreover, multiple peak fracture points can be observed due to intense grains interaction. In addition, the breakdown pressure has positive relationships with the pump rate and concentration of injection of plugging agents. Multiple fractures only exist for super-high-permeability unconsolidated sands with high pumping rate and low plugging agent concentration, which is primarily due to the plugging agent seal for both hydraulic fracture and the rock matrix. A low injection rate with low plugging agent concentration led to single-wing fracture for high-permeability unconsolidated sands, whereas a high injection rate with high plugging agent concentration led to single-wing fracture for low-permeability unconsolidated sands. Low plugging agent concentration is beneficial for aiding hydraulic fracture propagation along the maximum horizontal stress direction. In addition, the high-pump-rate and low-plugging-agent-concentration scenario and low-pump-rate and high-plugging-agent-concentration scenario have a greater chance of creating bi-wing fracture for super-high-permeability unconsolidated sands, whereas low pump rate and high plugging agent concentration are beneficial for bi-wing fracture for high-permeability unconsolidated sands. Local tortuous fracture path indicate tensile and fracture both exist during unconsolidated sands fracturing. With respect to sand control and large contact area, these treatments should be the better fracturing scenario for unconsolidated sand fracturing design with injection of a plugging agent. The findings of this study can help for better understanding of the fracturing mechanism and optimizing treatment parameters in unconsolidated sands fracturing.

One-step synthesis of porous graphene-based hydrogels containing oil droplets for drug delivery

Three-dimensional graphene hydrogels with a porous network have attractive potential in electrode materials, catalysis, and drug delivery. A series of porous graphene-based hydrogels containing oil droplets is fabricated on the basis of Pickering emulsions co-stabilized by graphene oxide and Fe3O4 nanoparticles. The volume ratio of water to oil and the concentration of stabilizers have significant effects on Pickering emulsion stability. A hierarchical pore structure is observed in the hybrid hydrogels prepared by in situ reduction of graphene oxide. Owing to the inner oil droplets distributing in the hydrogels which can be loaded with oil-soluble materials, the obtained reduced graphene oxide hydrogels show sustained release of hydrophobic drugs, which makes them a candidate for drug delivery.

Aqueous-Solution-Processed Hybrid Solar Cells from Poly(1,4-naphthalenevinylene) and CdTe Nanocrystals

Poly(1,4-naphthalenevinylene), prepared from a water-soluble precursor, was used to fabricate hybrid solar cells by blending with water-soluble CdTe nanocrystals (NCs) to act as the photoactive layer. In composites with CdTe NCs as the electron acceptors in a bulk heterojunction configuration, the devices exhibited a short-circuit current density of -6.14 mA/cm(2), an open-circuit voltage of 0.44 V, a fill factor of 0.32, and a power conversion efficiency of 0.86% under AM1.5G conditions. Because the devices were fabricated from water-soluble materials, the procedure was generally simple and environmentally friendly in comparison to the conventional devices fabricated from oil-soluble materials.

Industrial Applications of Microemulsions: A Patent Review

Since the inception of the concept of microemulsions by Hoar and Schulman in 1940, they have always been a key area of interest, both in terms of basic research as well as in industry, which is primarily due to their unique characteristics like thermodynamic stability, optical clarity, and ease of preparation. The existence of microdomains of different polarity with in the same, single-phase solution enables both water-soluble and oil-soluble materials to be solubilized, at the same time. Thus, owing to these features, the uses and applications of microemulsions have been numerous. It is, thus, the objective of this review to summarize the industrial applications of these novel surfactant systems by discussing the patents governing various applications of these systems. Keywords: Microemulsion, patent, oil, surfactant, cosurfactant, phase, stable, clear

The Excellent Water-Solubility of N-[3-(dimethyl-amino)propyl] docosanamide Chloride : The Most Eco-friendly Cationic Hair Conditioning Agent

A new hair-conditioning agent, N-[3-(dimethylamino)propyl]docosanamide (APA-22) hydrochloric acid salt (APA-22 HCl), has excellent solubility in water with a solubility limit over 10-times larger than that of other APA hydrochloric salts with shorter alkyl chain lengths. The physicochemical characteristics of APA-22 HCl were studied at 25 degrees C by using equilibrium surface tension (gamma), solubilization of an oil-soluble dye, steady-state fluorescence, and chloride ion selective electrode techniques. The APA-22 HCl salt is considered to form an aggregate at a concentration, C(1), which is about twice the concentration of the solubility limit of APAs with shorter alkyl chains. At a higher concentration, C(2), the aggregates of APA-22 HCl start forming another kind of aggregate, which is able to solubilize oil-soluble materials. That is, C(1) is considered to represent the critical aggregation concentration (cac) and C(2) a morphology transition. In the concentration region between C(1) and C(2) the solutions are seemingly transparent whereas at above C(2) they appear bluish or translucent. Since the Krafft point of APA-22 HCl is 55 degrees C, all the solutions, including the aggregates, are thought to exist in metastable states. Notably, however, these metastable solutions do not change significantly over a few months. The excellent solubility of APA-22 HCl in water is considered to be a result of this unique stepwise aggregation with increasing concentration.

A novel polymer anti-irritant barrier film for cosmetics

Currently, we encounter many chemical substances that can affect the skin through contact in our daily life. To keep these irritants away from us, it is very effective to create a dermal barrier film that can prevent penetration of irritants into the skin. For the purpose, we evaluated the permeation characteristics of currently available film-forming polymers, but almost all were found ineffective as barriers. Our investigation led us to fluoroalkylacrylate–polyglycolmethacrylate–alkylmethacrylate–copolymer (F–copolymer), a new acrylic copolymer. This polymer is soluble in water and can easily be incorporated into various cosmetic products. It consists of hydrophilic and lipophilic groups with fluorine units, and forms a durable, continuous film that is resistant to both water and oil upon drying. Testing on human subjects has demonstrated F-copolymer's effectiveness in countering irritation caused by water-soluble materials, including methyl paraben, lactic acid, and oil-soluble materials, like butyl paraben and methyl saricylate.

Detection of Water-soluble Natural Dyes by a Polyamide Batch Method

A method is described for the rapid detection of 11 water-soluble natural dyes in foods.A sample solution, prepared by aqueous extraction of foods, was shaken with ether to separate oil-soluble material. The solution was adjusted to pH 4-5. Polyamide powder (0.5g) was added to the solution, and the mixture was stirred for 15min. After filtration and washing with water, the dyes were eluted with 0.05% HCl in methanol.The dyes were identified by thin-layer chromatography and visible spectrophotometry.Since riboflavin was not adsorbed on polyamide, kaolin was used in this case.In the presence of organic acids, the extents of adsorption of safflower yellow, betanin, monascus pigments and riboflavin were reduced. In addition, sugar interfered with the adsorption of crocin blue, betanin and riboflavin.This method was applied for the detection of water-soluble natural dyes in candies, soft drinks and other foods.

Studies on Capsules

Dual walled capsules were made by a simpler method and their application possibilities were investigated. Oleoresins, essential oils and oil-soluble food colours were encapsulated into dual walled capsules (O/W/O' type) by using a multiple emulsion system. The dual walled capsule preparations were obtained through the three steps as follows.The first step; the oil-soluble materials were mechanically emulsified into an aqueous solution of gum arabic and gelatin with an emulsifying agents so as to form an O/W type.The second step; the O/W emulsion was mechanically emulsified into melted hardened oil and thus an O/W/O' emulsion was formed.The third step; the O/W/O' emulsion was sprayed into a chilled room to be solidified into droplets.These capsules have an unique dissolution pattern in ethyl alcohol and a relatively longer shelf life.In addition to these useful points, dual encapsulated oleoresins and essential oils have merits as far as sensory evaluation is concerned.

Penetration through the Egg-shell ofPieris brassicae(L.)

The structure of the shell of eggs ofPieris brassicae(L.), together with changes in it and associated membranes during embryonic development, have been investigated in relation to the penetration and toxicity of simple chemicals. The rigid outer shell consists of two proteinaceous layers, covered externally by a relatively hydrofuge cement, by which the egg is attached to the leaf surface. The egg has respiratory pores over its surface, and a single apical micropyle penetrating these layers. The inside of the rigid shell is lined with a layer of unsaturated oil—an unusual feature for an insect egg. When the egg is first laid, the vitelline membrane is directly applied to the inner surface of the solid shell over the region immediately around the micropyle, but within four hours this contact is broken, and the oil layer flows into this region also, and becomes complete. As development proceeds, the vitelline layer is replaced by membranes of embryonic origin, but before eclosion both these epembryonic layers, and also the oil, are resorbed.The egg is remarkably resistant to water-soluble poisons which have no oil-solubility, except during the first four hours of development. This resistance is attributed almost entirely to the oil layer, and the early susceptibility to its absence over the micropylar region. These changes are not reflected in the effect of oil-soluble poisons or fumigants. The solid portions of the shell do not seem to be of great importance in restricting the entry of liquid poisons, even though the cement is comparatively hydrofuge; from experiments with wetting agents and with eggs immersed in poisons under vacuum, it does not appear that the respiratory air spaces in the shell are preferential channels of access; rather, the poisons penetrate through the solid portions of the shell. This penetration, even of oil-soluble materials, is slow, for they can be effectively washed out of the shell again, some considerable time after dipping. On the other hand, non-volatile oily materials can interfere with the respiration of the egg by blocking the air spaces in the shell.The secretion of epembryonic layers does not appear to change the resistance of the egg to water-soluble materials; this is to be expected, for they do not contain lipoid. On the other hand they do add appreciably to the resistance to oil-soluble materials. There is no evidence that poisons are accumulated in these epembryonic membranes, and released during the pre-eclosion period. Experiments with covalent compounds, such as mercuric chloride, suggest that their oil-solubility accounts for their toxicity, whereas electrovalent compounds containing similar heavy metals are only effective while the direct micropylar path of entry is available to them.

The Formation and Structure of the Chorion of the Egg in an Hemipteran, Rhodnius prolixus

ABSTRACT The main regions of the Rhodnius prolixus egg-shell have been defined; a concise definition has been obtained for the term ‘chorion’. The formation and structure of the unspecialized chorion has been followed from the time of differentiation of the follicle cells, up to the completion of the shell, and an assessment made of the chemistry and permeability of each component shell layer. The follicle cells are binucleate ; changes in morphology and histology prior to secretion of the shell are outlined. The secretory products of the follicle cells fall naturally into an endoehorion and an exochorion; the endoehorion consists of five modifications of a proteinaceous substance. They are, in order of secretion: The Inner Polyphenol Layer, which consists of a series of tanned granules of average diameter 2 μ, containing large quantities of polyphenols. The layer is discontinuous and has no effect on permeability. The Resistant Protein Layer, a tanned and possibly vulcanized layer of protein, 1 to 2 μ thick, containing diffuse polyphenols. It is resistant to strong acids and bases, and permeable to water, ions, and large water-soluble molecules. The Outer Polyphenol Layer, which is similar to the inner layer, but has more minute granules. The Amber Layer.—This is the only coloured layer of the shell, and is less than 0-1 thick. It consists of tanned protein to which oil is added after secretion. It is therefore a lipidized protein, which is excessively resistant to acids and alkalies, and permeable to oils and oil-soluble material and to small ions and water. 5. The Soft Protein Layer.—This is a thick laminated layer some 8 ft thick, similar to, but less resistant than, the resistant protein layer. It contains polyphenols and tyrosine. The layer is freely permeable to -water-soluble substances. Throughout the secretion of the endochorion, the follicle cells stain deeply and appear to be filled with the protein components of the shell. The exochorion consists of two layers of the lipoprotein ‘chorionin ‘. 6. The Soft Exochorion Layer is a lipoprotein which is soluble in potash but not in strong acids ; the layer is permeable to lipoid solvents and to water and small ions, but not to larger particles. It is 8 p. thick at its maximum thickness, but contains follicular pits which, during secretion, are filled by long processes from the follicle cells. 7. The Resistant Exochorion Layer is a more resistant form of chorionin. It lines the pits and covers the surface of the shell, giving rise to the polygonal markings corresponding to the follicle cells, each with a pit at its centre. The follicle cells contain quantities of lipoprotein during this phase of secretion, and are difficult to stain. A method of staining is described which shows that pore canals of two varieties are present in the exochorion layers only. They run from the walls of the pits but do not reach the endochorion. None of the layers of the chorion waterproofs the shell. In the rear end of the shell, the outer polyphenol layer is displaced towards the exochorion, thus increasing the resistant protein layer and reducing the soft protein layer. It is shown that all seven layers are present in the neck, and in the central region of the cap, and that the order of secretion is the same. Modifications are produced by variations in the thickness of the various layers. In the neck, the soft protein layer is reduced ; in the cap, the resistant protein layer is reduced while the amber layer is 2/z. thick, giving the cap a brown appearance. The soft protein layer is extremely thin and irregular while the exochorion layers are 16/z, thick. Pore canals are again present in two varieties. Some analysis is made of the formation of follicular pits; this appears to be correlated with the thickness of the exochorion and endochorion layers.