The drilling of petroleum wells requires the use of suitable drilling fluids to ensure efficient operation without causing rock damage. Specific polymers have been used to control infiltration during drilling, to reduce operational problems. In this study, spherical microparticles of poly(methyl methacrylate‐co‐vinyl acetate) were synthesized (by suspension polymerization), characterized, and evaluated in terms of their performance in controlling filtrate loss of aqueous fluids. A filter press test with ceramic disk, simulating the rock, was used. The performance of the synthesized materials was compared with commercial polymers. It was observed that the performance of the material is directly associated with the relation between particle size and pore size of the rock specimen. Furthermore, for a suitable particle size, the rubbery characteristic of the material produces a more efficient filter cake, for filtrate control. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40646.

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Predicting the asphaltene stability in crude oils from different production streams is very useful in the petroleum industry because it allows avoiding serious problems caused by formation of solid deposits during oil flow. That prediction can be carried out by applying the solubility parameter (δ) of each oil, as calculated by the asphaltene precipitation onset value, obtained by titration with n-heptane. However, many crude oils do not have a well-defined precipitation onset point, which can be overcome by adding a crude oil assumed as the standard. This article analyzes the influence of a crude oil (called APS) on the precipitation onset of two other petroleum samples (called APA and APB). For this purpose, the asphaltene fractions C3I and C5I were extracted from APS, and the influence of the addition of this crude oil as well as its asphaltenes fractions in samples of oils APA and APB was evaluated by tests involving titration of n-heptane with detection by near-infrared spectroscopy (NIR). The calculation of the solubility parameters of the oils without well-defined precipitation onset, by adding the oil with well-defined precipitation onset, led to varied errors in function of the type of oil in question. The smallest errors were obtained when using, as the solubility parameter of the mixture (δM), the solubility parameter of the solvent system at the precipitation onset of the asphaltene C3I fraction (extracted from the crude oil assumed as the standard) in toluene, determined by titration with n-heptane.

During the drilling and completion of oil wells, the drilling fluid flowing down the annulus can invade the rock formation, possibly causing irreversible damage to the reservoir. One of the main functions of these fluids is to form a film with low permeability on the borehole wall to prevent invasion of filtrate in the rock formation. Polymeric additives are increasingly used to control these infiltrations. Recent studies have shown the potential of using microspheres made of poly(methyl methacrylate-co-vinyl acetate) (PMMA-co-PVAc) with dimensions compatible with the size of the formation pores. In this study, PMMA and PMMAco-PVAc polymers were synthesized by suspension polymerization, producing in the presence or absence of porogenic agents. The particles porosities influence the glass transition temperature, surface roughness and apparent density. The results also demonstrate that less rigid spheres with pores in their structure form a more efficient barrier against filtration to the rock formation. V C 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44484.

Three methods to obtain isoprene oligomers were evaluated: chemical degradation of non-vulcanized coagulated natural rubber; chemical degradation of natural rubber latex; and oligomerization of the isoprene monomer. The products were characterized by infrared spectrometry (FTIR), nuclear magnetic resonance (NMR) and size-exclusion chromatography (SEC). All the three processes were efficient and can be controlled in order to obtain products with desired molar mass. Among the degradation processes, the reaction with the non-vulcanized rubber led to the purest products, but this process has the disadvantage of relatively higher catalyst cost of the catalyst. Reactions of isoprene with free radical initiation produced oligomers under specific conditions: low isoprene concentration, low initiator concentration, and xylene as solvent. The results discussed here allows the readers to have a chemistry overview and experimental insights about different chemical routes to obtain isoprene oligomers, compiled together in the same work. It shall be helpful for applied chemistry researches.

One of the main problems faced while drilling oil wells is loss of fluid to the rock formation. This loss can be reduced with the use of chemical additives called filtrate controllers, which must be tailored to the specific characteristics of the rock formation and drilling conditions. In this study, copolymers made of methyl methacrylate-co-vinyl acetate were synthesized by the emulsion polymerization technique, the most efficient technique to obtain copolymers with widely differing reactivity ratios. The products were characterized and evaluated for filtrate reduction efficiency, in the form of an emulsion and a polymer suspended in water. The filtrate reduction percentage, on the order of 80%, increased with higher concentration of vinyl acetate. The use of the polymer suspended in water caused only a slightly greater reduction in filtrate loss than that produced by the respective emulsion. However, other important advantages are associated with the suspended formulation: lower optimal concentration ( 8.5 g/mL), formation of extremely discrete filter cake particles and better logistical aspects, since in the case of emulsions, the volume of material that must be transported is much greater.

Abstract.1 Aphrons were produced using nonionic surfactants by applying a differential pressure. Bubble size distribution was obtained from optical microscopy using FIJI-ImageJ2 program. The aim of this work was to correlate surfactants structures with aphrons properties (density and viscosity), size distribution and the number of bubbles. API fluid loss tests were based on standard proceedings specifications for water-based drilling fluids of Petrobras/Brazil. The structure of the nonionic surfactants showed a great influence on the fluid properties and the performance of the fluid contributing with a filtrate reduction up to 31% with the systems that were presented between 1088 and 1850 bubbles with diameters ranging from 33 to 104µm. These systems were produced by poly(ethylene oxide) with 7 ethylene oxide units, a poly(ethylene oxide)-b-poly(propylene oxide) with 6 ethylene oxide units and 3 propylene oxide units.

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