Pastas compósitas cimento/sílica/polímero para cimentação de poços de baixa profundidade sujeitas à injeção de vapor

The production of heavy oil fields, typical in the Northeastern region, is commonly stimulated by steam injection. High bottom hole temperatures are responsible not only for the development of deleterious stresses of the cement sheath but also for cement strength retrogression. To overcome this unfavorable scenario, polymeric admixtures can be added to cement slurries to improve its fracture energy and silica flour to prevent strength retrogression. Therefore, the objective of the present study was to investigate the effect of the addition of different concentrations of polyurethane (5-25%) to cement slurries containing 40% BWOC silica flour. The resulting slurries were characterized using standard API (American Petroleum Institute) laboratory tests. In addition to them, the mechanical properties of the slurries, including elastic modulus and microhardness were also evaluated. The results revealed that density, free water and stability of the composite cement/silica/polyurethane slurries were within acceptable limits. The rheological behavior of the slurries, including plastic viscosity, yield strength and gel strength increased with the addition of 10% BWOC polyurethane. The presence of polyurethane reduced the fluid loss of the slurries as well as their elastic modulus. Composite slurries also depicted longer setting times due to the presence of the polymer. As expected, both the mechanical strength and microhardness of the slurries decreased with the addition of polyurethane. However, at high bottom hole temperatures, the strength of the slurries containing silica and polyurethane was far superior than that of plain cement slurries. In summary, the use of polyurethane combined with silica is an interesting solution to better adequate the mechanical behavior of cement slurries to heavy oil fields subjected to steam injection

Formulação e caracterização de pastas espumadas por incorporação de ar e estabilizantes minerais

Cementing operations may occur at various stages of the life cycle of an oil well since its construction until its definitive abandonment. There are some situations in which the interest zones are depleted or have low fracture pressure. In such cases, the adoption of lowdensity cement slurries is an efficient solution. To this end, there are basically three ways to reduce the density of cement slurries: using microspheres, water extending additives or foamed cement. The objective of this study is to formulate, to study and to characterize lowdensity foamed cement, using an air entrainment surfactant with vermiculite or diatomite as water extenders and stabilizers. The methodology consists on preparation and evaluation of the slurries under the American Petroleum Institute (API) and the Brazilian Association of Technical Standards (ABNT) guidelines. Based on calculated densities between 13 and 15 ppg (1.559 and 1.799 g/cm3), the slurries were prepared with fixed surfactant concentration, varying the concentrations of vermiculite and diatomite and were compared with the base slurries. The results of plastic viscosity, yield point and gel strength and the compressive strength for 24 h showed that the slurries presented suitable rheology and mechanical strength for cementing operations in oil wells, and had their densities reduced between 8.40 and 11.89 ppg (1.007 and 1.426 g/cm3). The conclusion is that is possible, under atmospheric conditions, to obtain light weighted foamed cement slurries with satisfactory rheological and mechanical properties by means of air entrainment and mineral additions with extenders and stabilizers effects. The slurries have great potential for cementing operations; applicability in deep wells, in low fracture gradient formations and in depleted zones and bring cost savings by reducing the cementing consumption

Origem física das curvas sigmoidais respiratórias pressão-volume: recrutamento alveolar e elasticidade não-linear

An important unsolved problem in medical science concerns the physical origin of the sigmoidal shape of pressure volume curves of healthy (and some unhealthy) lungs. Such difficulties are expected because the lung, which is the most important structure in the respiratory system, is extremely complex. Its rheological properties are unknown and seem to depend on phenomena occurring from the alveolar scale up to the thoracic scale. Conventional wisdom holds that linear response, i.e., Hooke s law, together with alveolar overdistention, play a dominant role in respiration, but such assumptions cannot explainthe crucial empirical sigmoidal shape of the curves. In this doctorate thesis, we propose an alternative theory to solve this problem, based on the alveolar recruitment together with the nonlinear elasticity of the alveoli. This theory suggests that recruitment may be the predominant factor shaping these curves in the entire range of pressures normally employed in experiments. The proposed model correctly predicts the observed sigmoidal pressure volume curves, allowing us to discuss adequately the importance of this result, as well as its implications for medical practice

Micropartículas poliméricas à base de xilana e Eudragit® S-100 contendo mesalazina visando à liberação cólon-específica

Colon-specific drug delivery systems have attracted increasing attention from the pharmaceutical industry due to their ability of treating intestinal bowel diseases (IBD), which represent a public health problem in several countries. In spite of being considered a quite effective molecule for the treatment of IBD, mesalazine (5-ASA) is rapidly absorbed in the upper gastrointestinal tract and its systemic absorption leads to risks of adverse effects. The aim of this work was to develop a microparticulate system based on xylan and Eudragit® S- 100 (ES100) for colon-specific delivery of 5-ASA and evaluate the interaction between the polymers present in the systems. Additionaly, the physicochemical and rheological properties of xylan were also evaluated. Initially, xylan was extracted from corn cobs and characterized regarding the yield and rheological properties. Afterwards, 10 formulations were prepared in different xylan and ES100 weight ratios by spray-drying the polymer solutions in 0.6N NaOH and phosphate buffer pH 7.4. In addition, 3 formulations consisting of xylan microcapsules were produced by interfacial cross-linking polymerization and coated by ES100 by means of spray-drying in different polymer weight ratios of xylan and ES100. The microparticles were characterized regarding yield, morphology, homogeneity, visual aspect, crystallinity and thermal behavior. The polymer interaction was investigated by infrared spectroscopy. The extracted xylan was presented as a very fine and yellowish powder, with mean particle size smaller than 40μm. Regarding the rheological properties of xylan, they demonstrated that this polymer has a poor flow, low density and high cohesiveness. The microparticles obtained were shown to be spherical and aggregates could not be observed. They were found to present amorphous structure and have a very high thermal stability. The yield varied according to the polymer ratios. Moreover, it was confirmed that the interaction between xylan and ES100 occurs only by means of physical aggregation

Estudo de pré-formulação para dose fixa combinada dos tuberculostáticos rifampicina, isoniazida, pirazinamida e etambutol (4 em 1)

According to the global framework regarding new cases of tuberculosis, Brazil appears at the 18th place. Thus, the Ministry of Health has defined this disease as a priority in the governmental policies. As a consequence, studies concerning treatment and prevention have increased. Fixed-dose combination formulations (FDC) are recognized as beneficial and are recommended by WHO, but they present instability and loss on rifampicin bioavailability. The main purpose of this work was to carry out a pre-formulation study with the schedule 1 tuberculosis treatment drugs: rifampicin, isoniazid, pyrazinamide and ethambutol and pharmaceutical excipients (lactose, cellulose, magnesium stearate and talc), in order to develop an FDC product (150 mg of rifampicin + 75 mg of isoniazid + 400 mg of pyrazinamide + 250 mg of ethambutol). The studies consisted of the determination of particle size and distribution (Ferret s diameter) and shape through optical microscopy, as well as rheological and technological properties (bulk and tapped densities, Hausner Factor, Carr s Index, repose angle and flux rate) and interactions among drugs and drug excipient through thermal analysis (DSC, DTA, TG and your derivate). The results showed that, except isoniazid, the other drugs presented poor rheological properties, determined by the physical characteristics of the particles: small size and rod like particles shape for rifampicin; rectangular shape for pyrazinamide and ethambutol, beyond its low density. The 4 drug mixture also not presented flowability, particularly that one containing drug quantity indicated for the formulation of FDC products. In this mixture, isoniazid, that has the best flowability, was added in a lower concentration. The addition of microcrystalline cellulose, magnesium stearate and talc to the drug mixtures improved flowability properties. In DSC analysis probable interactions among drugs were found, supporting the hypothesis of ethambutol and pyrazinamide catalysis of the rifampicin-isoniazid reaction resulting in 3- formylrifamycin isonicotinyl hydrazone (HYD) as a degradation product. In the mixtures containing lactose Supertab® DSC curves evidenced incompatibility among drugs and excipient. In the DSC curves of mixtures containing cellulose MC101®, magnesium stearate and talc, no alterations were observed comparing to the drug profiles. The TG/DTG of the binary and ternary mixtures curves showed different thermogravimetrics profiles relating that observed to the drug isolated, with the thermal decomposition early supporting the evidences of incompatibilities showed in the DSC and DTA curves

Avaliação da argila atapulgita para potencial uso como excipiente farmacêutico em formas sólidas

Clays are natural materials that have great potential for use as excipients for solid dosage forms. Palygorskite is a type of clay that has hydrophilic properties as well as a large surface area, which could contribute to the dissolution of drugs. Thus, the present study aims to evaluate the use of palygorskite clay, from Piaui (Northeast region of Brazil), as a pharmaceutical excipient for solid dosage forms, using rifampicin and isoniazid as the model drugs. The former is a poorly soluble drug often associated with isoniazid for tuberculosis treatment. Palygorskite was characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), particle size, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and specific surface area (BET). The rheological and technological properties of palygorskite were determined and compared to those of talc, magnesium stearate and Aersosil 200. Mixtures between drugs and palygorskite were analyzed by differential scanning calorimetry (DSC), thermogravimetric analysis (TG) combined with thermal analysis (DTA) and Fourier Transform Infrared Spectroscopy (FT-IR), where the results were compared with those of the individual compounds. In addition, dissolution studies of solid dispersions and capsules containing the drugs, mixed with either palygorskite or a mixture of talc and magnesium stearate, were performed. The results showed that palygorskite has small particles with a high surface area. Its rheological characteristics were better than those of others commonly used glidants and lubricants. There was no interaction between palygorskite and the drugs (rifampicin and isoniazid). Among the dispersions studied, the mixture with palygorskite (5%) showed the highest drug dissolution when compared to other excipients. The dissolution of the rifampicin capsules containing palygosrkite was faster in higher concentrations. However, these differences were statistically different only in the first minutes of the dissolution experiment. The dissolution profile of isoniazid was also statistically different on the initial part of the experiment. The formulations prepared with isoniazid and palygorskite showed higher drug dissolution, but it was in descending order of concentration. According to these results, the palygorskite clay used in this study has great potential for application as an excipient for solid dosage forms

Avaliação da temperatura de cristalização da parafina em sistemas: parafina, solvente e tensoativo

The formation of paraffin deposits is common in the petroleum industry during production, transport and treatment stages. It happens due to modifications in the thermodynamic variables that alter the solubility of alkanes fractions present in petroleum. The deposition of paraffin can provoke significant and growing petroleum losses, arriving to block the flow, hindering to the production. This process is associated with the phases equilibrium L-S and the stages and nucleation, growth and agglomeration the crystals. That process is function of petroleum intrinsic characteristics and temperature and pressure variations, during production. Several preventive and corrective methods are used to control the paraffin crystallization, such as: use of chemical inhibitors, hot solvents injection, use of termochemistry reactions, and mechanical removal. But for offshore exploration this expensive problem needs more investigation. Many studies have been carried through Wax Appearance Temperature (WAT) of paraffin; therefore the formed crystals are responsible for the modification of the reologics properties of the oil, causing a lot off operational problems. From the determination of the WAT of a system it is possible to affirm if oil presents or not trend to the formation of organic deposits, making possible to foresee and to prevent problems of wax crystallization. The solvent n-paraffin has been widely used as fluid of perforation, raising the production costs when it is used in the removal paraffin deposits, needing an operational substitute. This study aims to determine the WAT of paraffin and the interference off additives in its reduction, being developed system paraffin/solvent/surfactant that propitiates the wax solubilization. Crystallization temperatures in varied paraffin concentrations and different solvents were established in the first stage of the experiments. In the second stage, using the methodology of variation of the photoelectric signal had been determined the temperature of crystallization of the systems and evaluated the interferences of additives to reduction of the WAT. The experimental results are expressed in function of the variations of the photoelectric signals during controlled cooling, innovating and validating this new methodology to determine WAT, relatively simple with relation the other applied that involve specific equipments and of high cost. Through the curves you differentiate of the results had been also identified to the critical stages of growth and agglomeration of the crystals that represent to the saturation of the system, indicating difficulties of flow due to the increase of the density

Constribuição técnica de um sistema de emulsão inversa a base de óleos vegetais para fluidos de perfuração

The developments in formulating drilling fluids to apply in petroleum fields are based on new technologies and environmental challenges, where the technical performance of a developed drilling fluid is used to produce a minimum environmental impact, showing great economy in costs. It is well known that the potential use of oil-based drilling fluids is limited because these fluids when discharged in the sea do not disperse as much as water-based ones and may form waterproof films in the seabed, having a profound effect on plants and animals living in this environment. The current works have been made in investigating fluids called pseudofluids, which are synthetic ester-based, n-paraffin-based and other fluids formed from inverse emulsion. In this research the principal parameters involved in inverse emulsion process were studied, in laboratory scale, using esters as main component. Others commercial drilling fluids were used as comparative samples, as well as samples from laboratory and field where these drilling fluids are being applied. Concentrations of emulsifier and organophilic clay, which are viscosity donor, were varied to verify the influence of these parameters, in different oil/water ratios (55/45, 60/40, 65/35, 70/30, and 75/25). The salt concentration (NaCl) is an indicative parameter of stability and activity of an esterbased fluid. In this research the salt concentration was varied in 10,000, 20,000, and 50,000 ppm of NaCl. Some rheological properties of the produced fluids were studied, such as: initial gel, plastic viscosity, yield point, and apparent viscosity. Through the obtained rheological measures, the existence of two systems could be verified: fluid and flocculated. It could be noticed that the systems were influenced, directly, by the oil/water ratio and emulsifier, organophilic clay and NaCl concentrations. This study showed the viability to use an ester obtained from a regional vegetable product babaçu coconut oil to obtain an efficient and environmental safe drilling fluid

Avaliação da molhabilidade de soluções de tensoativos em aço inoxidável

With the increasing industrialization of the planet caused by globalization, it has become increasingly common to search for highly resistant and durable materials for many diverse branches of activities. Thus, production and demand for materials that meet these requirements have constantly increased with time. In view of this, stainless steel is presented as one of the materials which are suitable applications, due to many features that are interesting for several segments of the industry. Concerns of oil companies over heavy oil reservoirs have grown steadily for the last decades. Rheological properties of these oils impair their transport in conventional flow systems. This problem has created the need to develop technologies to improve flow and transport, reducing operation costs so as to enable oil production in the reservoir. Therefore, surfactant-based chemical systems are proposed to optimize transport conditions, effected by reduction of interfacial tensions, thereby enhancing the flow of oil in ducts and reducing load losses by friction. In order to examine such interactions, a study on the wettability of metallic surfaces has been undertaken, represented by measuring of contact angle of surfactant solutions onto flat plates of 304 stainless steel. Aqueous solutions of KCl, surfactants and mixtures of surfactants, with linear and aromatic hydrocarbon chain and ethoxylation degrees ranging between 20 to 100, have been tested. The wettability was assessed by means of a DSA 100 krüss goniometer. The influence of roughness on the wettability was also investigated by machining and polished the stainless steel plates with sandpapers of references ranging between 100 of 1200. The results showed that sanding and polishing plates result in decrease of wettability. As for the solutions, they have provided better wettability of the stainless steel than the KCl solutions tested. It was also been concluded that surfactant mixtures is an option to be considered, since they promote interactions that generate satisfactory contact angles for a good wettability on the stainless steel plate. Another conclusion refers to the influence of the ethoxylation degree of the nonionic surfactant molecules on wettability. It has been observed that contact angles decrease with decreasing ethoxylation degrees. This leads us to conclude that molecules with higher ethoxylation degree, being more hydrophobic, decrease the interaction of water with the ducts, thereby reducing friction and improving the flow

Desenvolvimento de sistemas de pastas leves para aplicação em cimentação de poços petrolíferos com baixo gradiente de fratura

All around the world, naturally occurring hydrocarbon deposits, consisting of oil and gas contained within rocks called reservoir rocks , generally sandstone or carbonate exists. These deposits are in varying conditions of pressure and depth from a few hundred to several thousand meters. In general, shallow reservoirs have greater tendency to fracture, since they have low fracture gradient, ie fractures are formed even with relatively low hydrostatic columns of fluid. These low fracture gradient areas are particularly common in onshore areas, like the Rio Grande do Norte basin. During a well drilling, one of the most favorable phases for the occurrence of fractures is during cementing, since the cement slurry used can have greater densities than the maximum allowed by the rock structure. Furthermore, in areas which are already naturally fractured, the use of regular cement slurries causes fluid loss into the formation, which may give rise to failures cementations and formation damages. Commercially, there are alternatives to the development of lightweight cement slurries, but these fail either because of their enormous cost, or because the cement properties were not good enough for most general applications, being restricted to each transaction for which the cement paste was made, or both reasons. In this work a statistical design was made to determine the influence of three variables, defined as the calcium chloride concentration, vermiculite concentration and nanosilica concentration in the various properties of the cement. The use of vermiculite, a low density ore present in large amounts in northeastern Brazil, as extensor for cementing slurries, enabled the production of stable cements, with high water/cement ratio, excellent rheological properties and low densities, which were set at 12.5 lb / gal, despite the fact that lower densities could be achieved. It is also seen that the calcium chloride is very useful as gelling and thickening agent, and their use in combination with nanosilica has a great effect on gel strength of the cement. Hydrothermal Stability studies showed that the pastes were stable in these conditions, and mechanical resistance tests showed values of the order of up to 10 MPa

Preparação de resinas de poliuretana à base de óleo de mamona e dietanolamina

The aim of this work was the preparation of polyols from reactions between castor oil and dietanolamine to increase the hydroxyl content and the network degree in the products to application in electronic devices. The polyols and the mixtures obtained were characterized by nuclear magnetic ressonance. Castor oil (CO) is a natural triglyceride - based polyol possessing hydroxyl groups, which allow several reactions that produce many different products. Among them are the polyurethanes (PU), which have been considered an ideal product for the covering of electricelectronic circuits, due to their excellent electrical, shock-absorbing, solvents resistance and hydrolytic stability properties. About 90% of the fatty acids present in the castor oil are ricinoleic acid (12-hydroxyoleic acid), while the remaining 10% correspond to non-hydroxylated fatty acids, mainly linoleic and oleic acids. The chemical analysis of castor oil indicates a hydroxyl number of 2.7. In this work, a polyol was obtained by the reaction of the CO with diethanolamine (DEA), in order to elevate the hydroxyl value from 160 to 230 or to 280 mgKOH/g, and characterized by nuclear magnetic resonance (NMR) 1H and 13C (Mercury 200). The polyadition of the resulting polyol with isophorone diisocianate (IPDI) was carried out at 60°C, and the reaction kinetics was followed by rheological measurements in a Haake RS150 rheometer. The electrical properties were determined in a HP LCR Meter 4262A, at 1.0 Hz and 10.0 KHz. The chemical analysis showed that the polyols obtained presented hydroxyl number from 230 to 280 mgKOH/g. The polyadition reaction with IPDI produced polyurethane resins with the following properties: hardness in the range from 45 shore A to 65 shore D (ASTM D2240); a dielectric constant of 3.0, at 25°C (ASTM D150). Those results indicate that the obtained resins present compatible properties to the similar products of fossil origin, which are used nowadays for covering electric-electronic circuits. Therefore, the PUs from castor oil can be considered as alternative materials of renewable source, free from the highly harmful petroleum - derived solvents

Estudos das interações de quitosana/CTAB/C12E8

Surfactant-polymer interactions are widely used when required rheological properties for specific applications, such as the production of fluids for oil exploration. Studies of the interactions of chitosan with cationic surfactants has attracted attention by being able to cause changes in rheological parameters of the systems making room for new applications. The commercial chitosan represents an interesting alternative to these systems, since it is obtained from partial deacetylation of chitin: the residues sites acetylated can then be used for the polymer-surfactant interactions. Alkyl ethoxylated surfactants can be used in this system, since these non-ionic surfactants can interact with hydrophobic sites of chitosan, modifying the rheology of solutions or emulsions resultants, which depends on the relaxation phenomenon occurring in these systems. In this work, first, inverse emulsions were prepared from chitosan solution as the dispersed phase and cyclohexane as the continuous phase were, using CTAB as a surfactant. The rheological analysis of these emulsions showed pronounced pseudoplastic behavior. This behavior was attributed to interaction of "loops" of chitosan chains. Creep tests were also performed and gave further support to these discussions. Subsequently, in order to obtain more information about the interaction of chitosan with non-ionic surfactants, solutions of chitosan were mixed with C12E8 and and carried out rheological analysis and dynamic light scattering. The systems showed marked pseudoplastic behavior, which became less evident when the concentration of surfactant was increased. Arrhenius and KWW equations were used to obtain parameters of the apparent activation energy and relaxation rate distribution, respectively, to which were connected to the content of surfactant and temperature used in this work

Fluidos de perfuração aquosos: a contribuição da goma xantana e carboximetilcelulose no controle de filtrado

This study aimed mainly to evaluate the influence of xanthan gum (XG) and carboxymethylcellulose (CMC) in the filtration process of water-based drilling fluids, considering the conformational changes suffered by the polyelectrolyte with the addition of sodium chloride (NaCl) in different concentrations (0.17, 0.34 and 0.51 mol.L-1). It was also evaluated the behavior of the fluid by the addition of calcium carbonate (CaCO3) in pure water and in brine. Seeking a better understanding of the interaction between the polymers used and CaCO3, polymer adsorption analyzes were performed using a depletion method, which yielded a higher percentage of adsorption of Xanthan Gum in this material (29%), which can justify the formation of a thin and waterproof filter cake for drilling fluids containing this polymer. However, the best values of apparent viscosity (20 and 24 mPa.s) and volume of filtrate (8.0 and 8.1 mL) were obtained for the systems consisting of xanthan gum, CMC and CaCO3, in NaCl aqueous solutions concentrations of 0.34 and 0.51 mol.L-1, respectively. The values can be related to the presence of CMC that increases the apparent viscosity and reduces the volume of filtrate. In addition, the CaCO3 added acts as a bridging agent, promoting the formation of a less permeable filter cake

Desenvolvimento de pastas cimentantes contendo nanossílica como material estendedor para aplicação em fases iniciais, de poços petrolíferos, submetidas à baixa temperatura (5°c ± 3ºc)

The improved performance of hydraulic binders, the base of Portland cement, consists in the careful selection and application of materials that promote greater durability and reduced maintenance costs There is a wide variety of chemical additives used in Portland cement slurries for cementing oil wells. These are designed to work in temperatures below 0 ° C (frozen areas of land) to 300 ° C (thermal recovery wells and geothermal); pressure ranges near ambient pressure (in shallow wells) to greater than 200 MPa (in deep wells). Thus, additives make possible the adaptation of the cement slurries for application under various conditions. Among the materials used in Portland cement slurry, for oil wells, the materials with nanometer scale have been applied with good results. The nanossílica, formed by a dispersion of SiO2 particles, in the nanometer scale, when used in cement systems improves the plastic characteristics and mechanical properties of the hardened material. This dispersion is used commercially as filler material, modifier of rheological properties and / or in recovery processes construction. It is also used in many product formulations such as paints, plastics, synthetic rubbers, adhesives, sealants and insulating materials Based on the above, this study aims to evaluate the performance of nanossílica as extender additive and improver of the performance of cement slurries subjected to low temperatures (5 ° C ± 3 ° C) for application to early stages of marine oil wells. Cement slurries were formulated, with densities 11.0;12.0 and 13.0 ppg, and concentrations of 0; 0.5, 1.0 and 1.5%. The cement slurries were subjected to cold temperatures (5 ° C ± 3 ° C), and its evaluation performed by tests rheological stability, free water and compressive strength in accordance with the procedures set by API SPEC 10A. Thermal characterization tests (TG / DTA) and crystallographic (XRD) were also performed. The use of nanossílica promoted reduction of 30% of the volume of free water and increased compression resistance value of 54.2% with respect to the default cement slurry. Therefore, nanossílica presented as a promising material for use in cement slurries used in the early stages of low-temperature oil wells

Avaliação de compatibilidade entre pasta de cimento e fluido de perfuração não-aquoso utilizados em poços petrolíferos

Compatibility testing between a drilling fluid and a cement slurry is one of the steps before an operation of cementing oil wells. This test allows us to evaluate the main effects that contamination of these two fluids may cause the technological properties of a cement paste. The interactions between cement paste and drilling fluid, because its different chemical compositions, may affect the cement hydration reactions, damaging the cementing operation. Thus, we carried out the study of the compatibility of non-aqueous drilling fluid and a cement slurry additives. The preparation procedures of the non-aqueous drilling fluid, the cement paste and completion of compatibility testing were performed as set out by the oil industry standards. In the compatibility test is evaluated rheological properties, thickening time, stability and compressive strength of cement pastes. We also conducted analyzes of scanning electron microscopy and X-ray diffraction of the mixture obtained by the compatibility test to determine the microstructural changes in cement pastes. The compatibility test showed no visual changes in the properties of the cement paste, as phase separation. However, after the addition of nonaqueous drilling fluid to cement slurry there was an increased amount of plastic viscosity, the yield point and gel strength. Among the major causative factors can include: chemical reaction of the components present in the non-aqueous drilling fluid as the primary emulsifier, wetting agent and paraffin oil, with the chemical constituents of the cement. There was a reduction in the compressive strength of the cement paste after mixing with this drilling fluid. Thickening test showed that the oil wetting agent and high salinity of the non-aqueous fluid have accelerating action of the handle of the cement paste time. The stability of the cement paste is impaired to the extent that there is increased contamination of the cement slurry with the nonaqueous fluid. The X-ray diffraction identified the formation of portlandite and calcium silicate in contaminated samples. The scanning electron microscopy confirmed the development of the identified structures in the X-ray diffraction and also found the presence of wells in the cured cement paste. The latter, formed by the emulsion stability of the drilling fluid in the cement paste, corroborate the reduction of mechanical strength. The oil wetting agent component of the non-aqueous drilling fluid, the modified cement hydration processes, mainly affecting the setting time.