Search

Summary Chemical EOR is one of the more attractive methods to improve oil recovery. Numerous successful projects including injectivity tests, pilots and full-field developments have been executed without major injectivity issues or decline. Nevertheless, this topic remains a concern among operators. Polymer Flooding has seen more interest from the industry, and more challenging reservoirs (low permeability formations) are considered—thus raising concerns about injectivity. Filter ratio is routinely used as an injectivity screening criteria, but does it correlate with polymer injectivity and propagation during coreflood experiments, especially in the presence of crude oil? This paper provides new insights on polymer injectivity in cores considering polymer molecular weight, chemistry, rock permeability and mineralogy. The results are obtained from dedicated experiments and examination of several extensive data bases (including the literature). State of the art commercial polymers of varying chemistry with molecular weight ranging from 5 to 27+ MDa were injected into different sandstone cores having permeabilities between 10 to 200 mD with a range of clay content. Filter ratio was also determined and compared to injectivity in cores. All the data comes from field project case studies using reservoir cores and representative outcrop cores. For HPAM, injectivity was not a concern. It was possible to propagate up to 27+ MDa HPAM in a 100–200 mD core without significant pressure build-up. Concerning ATBS polymers, injectivity initially appeared to be constrained by the ATBS content; a 15 MDa polymer with a medium-high ATBS content poorly propagated below 200 mD. However, optimization based on molecular weight for similar ATBS content showed stable propagation in representative porous media. Finally, the filter ratio test did not always correlate to injectivity. Indeed, it was observed that several 1.2 µm FR tests (performed on high Mw polymers) failed despite successful transport in cores having permeability below 200 mD. In addition, acrylamide-based terpolymers allowed improvement in transport of ATBS polymers - a 20 MDa polymer containing medium level of ATBS was able to propagate in less than 100-mD cores. These observations are applicable to cores having clay content below 5%. For higher clay content, injectivity should be assessed case by case using reservoir core and crude oil. This paper establishes new references in terms of polymer transport behavior in porous media and highlights the importance of appropriate selection of polymer, polymer quality and experimental protocols to properly assess polymer injectivity in cores. Significance of the proposed paper: 1. Extensively examines the lower limits of permeability for injection of synthetic polymers, especially as a function of polymer molecular weight, polymer composition, rock mineralogy, and the presence of residual oil. 2. Better characterizes the relations between filter ratio, permeability and polymer injectivity in low-permeability rock.

Summary Diadema Oil Field is located in the San Jorge Gulf Basin in Southern Argentina. The field is operated by CAPSA, an Argentinean oil producer company; it has around 500 producer and 300 injector wells (well spacing is around 250 m). The company has been developing water flooding during more than 25 years (today this technique represents +65% of oil production), polymer flooding during more than 10 years and (+15% of oil production); produces about 1,850 m3/d of oil and 45,000 m3/d of gross production (96% water cut) with 43,000 m3/d of water injection. The main reservoir under secondary recovery is characterized by high permeability (500 md average), high heterogeneity (10 to 5000 md), high porosity (30%), very stratified sand-stone layers (4 to 12 m of net thickness) with poor lateral continuity (fluvial origin) and 20 °API oil (100 cp at reservoir conditions, 50 °C). Due to such reservoir conditions, injectors and producers are subject to channeling problems. Polymer gels have been extensively used to tackle such conformance issues. The criteria of success do not only depend on the quality of the technical solution but also on economics. Generally, gels are formulated using polymers under powder form requiring the mobilization of a dissolution unit, a maturation tank and one to several dilution tanks. On the opposite the utilization of polymers under reverse emulsion form only requires the use of a single skid including a static mixer for the inversion of the emulsion and one or two static mixers for polymer dilution and homogenization with the crosslinker, reducing both the footprint of the equipment (important for offshore) and the cost of the treatment. Two gel formulations using Chromium (III) acetate as crosslinker and partially hydrolyzed polyacrylamide either under its powder or its reverse emulsion version were developed to fit field conditions targeting a gel D category according to Sydansk classification and a gel time below 36 hours. A cost analysis comparison of both formulations was performed to select the more efficient solutions. Gels C to D were achieved for both formulations, 15 hours gel time and good stability over 3 months. The economical evaluation showed that the cost saving associated to the use of a single skid did not compensate the extra price of the reverse emulsion compared to the powder. The formulation using HPAM as a powder was selected and 20+ injection wells were treated without facing any operational issue.

Summary Polymer flooding has proven to be an effective technique to improve oil recovery from mature reservoirs. The selection of polymer, focusing mainly on its temperature tolerance properties and its ability to propagate in porous media, is key to achieve a successful EOR job. This selection also depends on brine injection compositions that covers a large range of salinities and hardness worldwide. A screening of viscosity behavior with different polymers in different brine conditions is obviously helpful in order to select the most cost effective chemistry. The impact of different acrylamide based polymer chemistries is evaluated through viscosity measurement over a wide range of salinities and hardness. A parameter called R+, corresponding to the molar ratio of divalent cations divided by the total mole number of cations in the brine is introduced. Salt tolerance and hardness tolerance of polymers in solutions are evaluated for brine considering either constant Total Dissolved Salt (TDS) with different R+ either the impact of different total salinities for constant R+. This parameter is as well considered to compare shear stability of the different polymers. At least, the impact of the type of divalent cations on viscosity is reported. Polymers from the study are all anionic and acrylamide based. The introduction of different amounts of sulfonated monomer (ATBS) was performed and its impact on hardness and shear tolerance was assessed. For all the polymers, a threshold beyond which viscosity remains constant is reached for R+> 0,5. Interestingly, this threshold is obtained for lower value of R+ for polymers containing ATBS since they provide better calcium tolerance. Calcium provides a higher impact on viscosity compared to magnesium for all the polymers studied. Increasing the amount of ATBS leads to higher tolerance to divalent cations. It also provides better stability to shear degradation. A minimum amount of sulfonated monomer is required to improve stability. The objective of this paper is to complete guidelines in the selection of industrial polymers considering a wide range of salinities and hardness. The screening of brine and polymers selected for this study is wide enough to represent worldwide injection brine conditions and helps selecting the most appropriate chemistry for each reservoir condition.

Foam injection has been proven to be an efficient technique for EOR applications, stimulation operations and profile control. However, foam is known to have low stability and poor oil tolerance but adding polymer is reported to be an efficient way to improve such foam stability. An extensive study has been undertaken with different surfactants (foaming agents) and polymers to screen out the surfactant/polymer combinations providing the highest foam stability. We performed a systematic study consisting of static tests (foamability, stability) from which we selected two surfactants (nonionic and anionic) and two polymers (nonionic and associative polymer) expected to highly improve foam performances. Core-flood experiments were performed in high-permeability sandpacks in successive sequences starting with foam propagation, followed by a water flow and then an oil backflow. The Resistance Factor (RF) has been measured for each flow sequence. Based on our experiments, polymer-enhanced foams is shown to be a promising way for profile control during waterflood and recommendation of use of an associative polymer instead of a classical nonionic polymer is discussed.

Fibre-optics diffuse reflectance spectroscopy (FORS) was used to characterise pigment mixtures in paints used in art. Measurements are non invasive, without any contact with the sample. The experimental device is portable, therefore measurements can be performed in situ, without moving the work of art under investigation from its conservation place. The protocol was validated thanks to modern gouache paints: 10 pure gouaches were used as references and 27 binary mixtures of these pure gouaches were studied. Reflectance spectra are processed using the Kubelka–Munk theory in order to get scattering and absorption coefficients of the references. Assuming a linear dependance of these optical properties with the pigment volume concentration (PVC) of the components of paint layers, the protocol enables qualitative as well as quantitative interpretation of the reflectance spectra measured on binary mixtures of references. Indeed, for most cases, numerical processing of FORS-measurements performed on a mixture leads to the identification of its components. Besides, once the components are identified, it is possible to compute their respective proportions with an accuracy of 5%.

Fibre-optics diffuse-reflectance spectroscopy was used to evaluate pigment quantity in art glazes. Measurements are non-invasive, without any contact, and can be performed in situ, without moving the work of art under investigation from its conservation place. Reflectance spectra are processed using Kubelka–Munk theory in order to obtain scattering and absorption parameters of the samples. Assuming a linear dependance of these optical properties with the pigment volume concentration of the paint layers, we were able to evaluate pigment quantities in the samples from reflectance measurements. Results are in excellent agreement with those obtained by X-ray diffraction and micro-X-ray fluorescence.

For colonic delivery, pectin beads obtained by ionotropic gelation method have been already reported as an interesting approach. This study investigated the influence of the cross-linking agent (calcium or zinc) and the type of shell capsule used (classical or enteric capsules) on pectin beads properties and on their performance to target the colon (in vitro dissolution studies with subsequent pH change to mimic overall gastro-intestinal tract). Zinc pectinate beads seemed to be relatively similar to calcium's ones in morphological point, except on the surface aspect. When beads were introduced in classical hard capsules, ketoprofen release was not significantly different between CPG and ZPG beads, and it was too premature and too quick due to a chemical erosion of the pectinate matrix (acid + basic attacks). However, zinc pectinate beads showed slower ketoprofen release compared with calcium pectinate beads when enteric hard capsules were used. This interesting finding could be due to the strength of the network formed during the process between the zinc cations and the LM-pectin following the "egg-box" model. This network was stronger and induced a reduction of swelling and hydration when contact with dissolution medium, then subsequently a decrease of drug release. Thus, the zinc pectinate beads could protect sufficiently drug entrapped from the upper gastro-intestinal conditions and drug release will be controlled by pectin degradation with colonic microflora. Finally, these zinc pectinate beads in enteric hard capsules are promising as a carrier for specific colonic delivery of drugs after oral administration.

In this study, pectinate gel beads were produced by ionotropic gelation method with different solutions of cross-linking agents and ketoprofen was entrapped as model drug. The influence of these formulation parameters was investigated upon bead properties and upon their performance to target the colon. Zinc pectinate beads obtained with 10% of counter-ions solution at pH 1.6 exhibited the strongest gel network due to "egg-box" dimmer formation helped by hydrogen bonding. Furthermore the gel network formed at low pH was arranged in a compact three-fold conformation. Thus, this matrix structure in enteric capsules induced the lowest drug release in the upper gastro-intestinal tract (pH 1.2 following by pH 7.4). However ketoprofen release occurred specifically in the colon thanks to the presence of pectinolytic enzymes and the release rate can be modulated by the counter-ion concentration during the reticulation process. Therefore this approach using pectinate beads is very promising as efficient carrier for specific delivery of drug into the colon, after oral administration.

The qualitative and quantitative significance of nannoplankton in Lake Superior in terms of taxonomy and primary production was studied during 1973. The size analysis of algae into netplankton (≥64μm) and nannoplankton (

In view of the large variation found in plant cell wall digestibilities with ruminants, an attempt was made to group 124 feeds into different lignification classes (clusters) on the basis of chemical characteristics. Each feed cluster was described using a structural coefficient [Formula: see text] that related the potentially digestible fiber (PDF, %) to the ratio between lignin and cell wall volume. The optimum number of clusters was determined iteratively by performing a regression of the apparent digestibility of dry matter at maintenance level (DDM1, %) against the PDF and cell soluble (SOL, %) contents of feeds. The [Formula: see text] coefficients varied from 0.05 (grains, N = 13) to 1.85 (corn silage, N = 3) and increased with the maturity of the grasses from 0.88 (legumes, vegetative cool season grasses, N = 26) to 1.33 (mature, cool season grasses, N = 19). Predicted PDF were closely correlated (r > 0.9, P 1 discounted for intake (DDM1 – 4, %) was regressed against SOL and PDF concentrations of 87 feeds:[Formula: see text]with ds and df, the true digestibilities of SOL and PDF. Estimates of ds and df were 0.98 and 0.95 for a zero-production (maintenance) level of intake, and 0.91 and 0.79 for an intake level four times maintenance. Since the true digestibility of the PDF component was only 4% – 13% lower than that of the cell soluble component, the concentration of PDF in cell wall was the major determinant in the variation in apparent digestibility of forages. Key words: lignin, neutral detergent fiber, true digestibility, cluster analysis, feeds

Phytohemagglutinin M (PHAM) has been purified from the commercial mixture of proteins produced by Phaseolus vulgaris, using a Sepharose-thyroglobulin column. The protein gave one band on gel electrophoresis and two bands on SDS-gel electrophoresis (mol. wt. 33 700 and 32 100, respectively). Molecular weight determination by ultracentrifugation gave a value of 61 200 +/- 700. The protein had a minimum sugar content of 16%. Binding studies of PHAM to purified rat spleen lymphocytes have been performed at 0, 25, and 37 degrees C. It was shown that the cells bound about the same amount of lectin at 0 and 37 degrees C, but less protein was bound at 25 degrees C. The binding phenomenon showed saturability at all temperatures. Data were analyzed by Scatchard plots and two kinds of binding sites were found. High-affinity sites and low-affinity sites have been characterized in terms of association constants and (apparent) number. It was also shown that cells treated with trypsin or sodium azide bound less lectin. Bound concanavalin A did not appear to affect the amount of bound PHAM, but its influence was reflected in the value of the association constant for the binding of PHAM. Unlabelled PHAM was shown to displace radioactive PHAM from the cells, but could not remove bound concanavalin A. The significance of these results is discussed in terms of the fluid plasma membrane model and cellular metabolism.

1. Inward and outward currents were recorded in the human Jurkat T cell line using the whole-cell configuration of the patch-clamp technique. 2. The transient outward current was activated at membrane potentials positive to -60 mV. The activation time constant-voltage relationship decreased from 17 ms to 2 ms for membrane potentials ranging from -40 to +40 mV. The inactivation phase could be fitted by a single-exponential function and the inactivation time constant decreased from 250 ms to 150 ms for membrane potentials ranging from -20 to +100 mV. 3. The steady-state inactivation-voltage relationship showed a mid-point potential of -32 +/- 2.6 mV, and the slope factor was 10.8 +/- 1.8 mv (n = 3). 4. The calcium ionophore A23187 provoked a decrease in the amplitude of the outward current, suggesting a dependence of this current on the cytosolic concentration of Ca2+. 5. The K+ outward current was blocked by tetraethylammonium (TEA, Michaelis-Menten constant (Km), 6 mM) and by the calcium channel blockers Ni2+, Co2+, Mn2+ and Cd2+. 6. Forty per cent (n = 120) of the patched Jurkat cells displayed an inward current. In a physiological medium containing Ca2+ (2.2 mM), the inward current threshold voltage was -60 mV, the maximum current was observed at -40 mV and the zero current voltage was positive to +20 mV. At negative membrane potentials, the time required to reach 50% of the maximum amplitude was 60 ms and grew shorter with increasing depolarization, reaching a value of 5 ms at -5 mV. The inactivation of the inward current was very slow and the time constant varied from 1200 ms at -35 mV to approximately 250 ms for potentials positive to -10 mV. 7. The current availability had a value of one for potentials negative to -50 mV and zero for potentials positive to -15 mV. The mid-point potential was -31 +/- 3.4 mV and the slope factor was 3.3 +/- 0.2 mV (n = 3). 8. The inward channels were permeable to Sr2+, but were blocked by classical Ca2+ channel inhibitors such as Co2+, Mn2+ and Ni2+. 9. Phaseolus vulgaris phytohaemagglutinin (PHA), an inducer of interleukin-2 production in Jurkat cells, increased the inward current amplitude by 32 +/- 20% (n = 4). This increase was concomitant with a decrease (45 +/- 12%) in the amplitude of the outward current, but only when the current was carried by Ca2+.(ABSTRACT TRUNCATED AT 400 WORDS)

Forty-eight wethers were used to determine voluntary intake and digestibility of eight silages made from pure swards of legumes and grasses. Chemical and physical characteristics of silages were measured and related to dry matter intake, digestibility coefficients and digestible nutrient intakes by means of simple correlation and linear regression analyses. Intakes of dry matter (DM), digestible energy, digestible protein and total digestible nutrients were correlated negatively with percentage cell walls (r = −0.87) and positively with crude protein (r = 0.92). Lignin and the logarithm of (lignin × 100/acid detergent fiber) were highly correlated to cell walls digestibility (r = 0.98). There was a close relationship between protein digestibility and crude protein content (r = 0.99). Dry matter digestibility was accurately estimated by a summative equation (r = 0.74). The physical characteristics (packed volume and water solubility) of the silages were not well correlated to either digestibility coefficients or intake. The nutritive value of good quality, well-preserved grass and legume silages was satisfactorily predicted from laboratory analyses of crude protein and cell wall components. The applicability of the equations developed in this study should be tested using a larger number of silages. Key words: Nutritive value, forages, silages, sheep

Following deep plowing and subsoiling treatment in 1971, alfalfa and corn silage were grown continuously during a 5-yr period on Chaloupe soils which have an indurated layer at 40 cm or deeper. These soils were formed from laminated particles of very fine sand and loam of recent sedimentary origin. Measurements taken in 1972 and 1975 included bulk density, resistance to penetration, permeability, organic matter content and soil texture. Subsoiling did not significantly change soil physical properties; only a slice of soilless than 10 cm wide at depth 50 cm and deeper on each side of and in the furrow made by the ripper showed modifications, without affecting crop yields. Deep plowing, however, in turning the soil by 120° to 150° resulted in redistribution of the organic matter and the soil texture down the profile, a diminution in resistance to penetration in the subsoil. But it did not change the porosity or the permeability of the lower layers. Physical modifications brought by deep plowing were still persistent after more than a 3-yr period. Improvement in physical and hydrodynamic soil properties following deep plowing did not have any beneficial effect on corn and alfalfa yields.

The degradation of chlorotoluron, 1-(3-chloro-4-methylphenyl)-3,3-dimethylurea, was investigated in laboratory and field-grown wheat and soil. Thin-layer cochromatography and, partially, derivatization and mass spectroscopy were used to elucidate the structures of the metabolites. Wheat treated with 4-methyl[ 14 C]-phenyl-labeled chlorotoluron rapidly metabolized the herbicide using two independent mechanisms: (I) oxidation of the 4-methylphenyl group to yield 4-hydroxy-methylphenyl and 4-carboxyphenyl derivatives; and (II) N -demethylation. Mechanism (I) clearly predominated over mechanism (II). Young wheat degraded the herbicide mainly to 4-hydroxy-methylphenyl derivatives with only a small fraction being additionally N -monodemethylated. Most of both metabolites was conjugated, most probably, with glucose. In straw and grains of mature field-grown summer wheat treated postemergence with labeled chlorotoluron at a rate corresponding to 2 kg active ingredient/hectare 2.8 ppm and 0.12 ppm radioactivity equivalent to chlorotoluron were found, respectively. About 50% of this terminal radioactivity was nonextractable by organic solvents. No chlorotoluron or its N -demethylated derivatives were present in either plant part. About 40% of the radioactivity in straw consisted of 4-carboxyphenyl derivatives half of which were N -mono- or didemethylated. The rest of the terminal radioactivity was mainly in form of the 4-hydroxymethylphenyl derivative of chlorotoluron. Less than 20% of the soluble metabolites was present as conjugates. In soil mechanism (II) exceeded mechanism (I). At harvest of the wheat the 0.4 ppm radioactivity of the 0- to 30-cm soil layer was composed of 43% chlorotoluron, 36% N -mono- and 3% N -didemethylated chlorotoluron, as well as 13% 4-carboxyphenyl derivatives partly N -demethylated.

The metabolic fate of 14C-labe1ed GS-13005 ( S - ((2- methoxy-5-oxo-Δ2-1,3,4-thiadiazolin-4-yl) methyl) O,O -dimethyl phosphorodithioate), the active ingredient of the insecticide Supracide® was followed in plants, soil, and animals. A rapid degradation of this insecticide in all investigated was observed. In addition to the hydrolysis of the ester bond, the heterocyclic moiety of GS-13005 was cleaved, and the fragments originating were oxidized to CO2 which represented the main metabolite. The pattern of metabolites in bean and alfalfa plants consisted of almost exclusively polar substances, approximately ⅓ of which liberated GS-12956 (2-methoxy-Δ2-1,3,4-thiadiazolin-5-one) after hydrolysis. Only trace amounts of the corresponding P-O derivative, GS-13007 ( O -[(2-methoxy-5-oxo-Δ2-1,3,4-thiadiazolin-4-yl)-methyl] O,O -dimethyl phosphorothioate, and of G5-12956 were detected. The pronounced degradation of GS-13005 in 2 types of soil was suppressed after steam sterilization emphasizing the role of the soil microorganisms. Locusts metabolized the thiadiazole ring of GS-13005 resulting in the liberation of 14CO2 and an increasing amount of water-soluble metabolites. Urine and expired air were the main routes for the excretion of metabolites of GS-13005 orally applied to rats. ro accumulation of GS-13005 or its metabolites was observed in any organ of the rat after feeding the insecticide for 10 days. In addition to 14CO2, the sulfoxide derivative, GS-28370 (2-methoxy-4-methylsulfinylmcthylorganisms Δ2-1,3,4-thiadiazolin-5-one), and the sulfone derivative, GS-28369 (2-methoxy-4-methylsulfonylmethyl-Δ2-1,3,4-thiadiazolin-5-one), were determined as the main metabolites of the urine. These metabolites are not cholinesterase esterase inhibitors and have acute toxicities in the range of only 1/15-1/50 of the parent insecticide. The metabolic fate of these metabolites and of GS-12956 was followed to determine the sequence of the metabolic reactions taking place in the course of the degradation of GS-13005 in the rat. The mechanism of the degradation of GS-13005 in the rat was investigated in vitro systems demonstrating methionine as the methyl donor for the synthesis of the main metabolites. Absence of GS-13005 and its oxidation product, GS-13007, in the milk of a goat was demonstrated. Only 0.6% of the dose orally applied was found in the form of polar metabolites.

An enzyme-linked immunosorbent assay (ELISA) was developed to detect immunoglobulin G to Coxiella burnetii phase II. Serum samples from 213 patients who had had Q fever 1 year previously and from 301 blood donors from six localities in Switzerland were tested by ELISA and by indirect fluorescent-antibody (IFA) and complement fixation (CF) tests. The ELISA and the IFA and CF tests detected antibody to C. burnetii in 202 (94.8%), 193 (90.6%), and 166 (77.8%) of the 213 Q fever patients, respectively. With the serum samples from blood donors, the ELISA yielded a higher percentage of positive sera than did the IFA and CF tests. The high specificity of the three tests was confirmed by analyzing paired serum samples from 36 patients suffering from acute pneumonia of viral or bacterial origin. In these cases, the serological results were negative by the three tests, except for three Q-fever cases included as positive control.

A study of the reaction of a hapten, alantolactone, with some amino acids is reported. Previously, we have reported than an α-methylene group attached to the γ-lactone is the immunologic requisite of alantolactone and some other sesquiterpene lactones. Such a group is known to be capable of undergoing "Michael-type addition" with the sulfhydryl group of cysteine. We confirm this finding and report that alantolactone can also undergo addition with the imidazole group of histidine and with the ε-amino group of lysine, but not with the guanido group of arginine, the hydroxyl group of serine, or the thio ether function of methionine. We selected these amino acids for further study because of their nucleophilic side chain. Samples of alantolactone that have undergone such addition no longer produce allergic eczematous contact dermatitis, as measured by patch test.

Summary.— By patch testing cross-sensitivity was not observed between the sesquiterpene lactone, alantolactone (from Inula) and ilicic acid, which is an unsaturated sesquiterpenoid lacking a lactone ring (from Ambrosia) and α-methylene-γ-butyrolactone (from Tulipa) which is the simplest structure containing the grouping that is characteristic of the active compounds; and protolichesterinic acid (from the lichen Cetraria) which is an unsaturated lactonic acid. Some 50 additional potentially allergenic sesquiterpene lactones derived from plants are listed from the families, Compositae, Lauraceae, and Magnoliaceae; some lactones from the family Umbelliferae are also listed.

Cinnamylpyrogallol was found to be a greater inhibitor of fungal growth than either cinnamyl alcohol or pyrogallol. Antifungal activity decreased with time owing to oxidation of the compound in solution. Cinnamylphloroglucinol was less active than cinnamylpyrogallol against the 27 species of fungi (including dermatophytes) tested. In addition these substances also were active against two of the four bacterial species tested.