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The aim of this study was to evaluate changes in airflow characteristics before and after septoplasty in unilateral cleft lip and palate (UCLP) patients using computational fluid dynamics (CFD) models. The study was designed as a prospective cohort study involving pre- and postoperative computed tomography data from 12 UCLP patients with a deviated nasal septum who underwent septoplasty. CFD analysis of nasal airflow was conducted to study changes in velocity, pressure, volume, nasal resistance, and wall shear stress of the nasal domain before and after surgery. The study results demonstrated a statistically significant difference in pressure drop after septoplasty: median 116.10Pa (interquartile range (IQR) 749.02Pa) preoperative compared with 43.39Pa (IQR 349.01Pa) postoperative (P= 0.004). Maximum wall shear stress was found to be approximately three times lower after septoplasty: median 6.15 Pa (IQR 1908.62 Pa) preoperative versus median 2.51 Pa (IQR 540.06 Pa) postoperative (P=0.002). Changes in nasal resistance were also found to be statistically significant: median 460.59 Pa·s/l (IQR 1946.99 Pa·s/l) preoperative versus median 166.61 Pa·s/l (IQR 694.08 Pa·s/l) postoperative (P=0.04). These values demonstrate significant changes in flow dynamics after surgery indicative of a more uniform airflow pattern and stabilization of the nasal mucosa.

Purpose To report the clinical profile of a series of anterior nodular scleritis in Indian population. Methods We conducted a retrospective review of medical records of 140 eyes of 123 consecutive patients with nodular scleritis who presented to a tertiary eye care institute between 2007 and 2018. Results The mean age at presentation was 46.8 ± 13.1 years and 70.7% of the patients were female. Bilateral involvement was observed in 14% patients. The most common presenting symptom was redness (92.6%) and ocular pain (69.1%). Twenty-seven patients (22%) had some systemic association and rheumatoid arthritis (5%) was the most common autoimmune disease. Presumed ocular tuberculosis was diagnosed in 13% patients. Methotrexate was the most common immunosuppressive used in these patients and an additional immunosuppressive was required in 6.5% patients. Recurrence of inflammation was observed in 74.8% patients. Deterioration of vision noted in 2.8% eyes. Conclusion Tuberculosis remains an important cause of nodular scleritis in India. Recurrence of scleritis is common in nodular scleritis and cases with non infectious nodular scleritis often require treatment with immune suppressives.

To report the clinical profile of cataract and its surgical management in a scleritis cohort from India. We conducted a retrospective review of medical records of 39 eyes of 32 consecutive patients...

Purpose: To examine the clinical profile of sympathetic ophthalmia among the pediatric age group. Methods: Retrospective review of patients 18 years and younger with sympathetic ophthalmia seen in a tertiary eye care center between 1997 and 2017. Results: Of 20 patients included in the study, 70% were male. The most common inciting event for sympathetic ophthalmia was trauma (85%), followed by vitreoretinal surgery (15%). All patients were treated with systemic steroids. Seventeen patients received additional corticosteroid-sparing immunosuppressive agents, and 4 patients (20%) required more than one immunosuppressive agent. Azathioprine was the most commonly used corticosteroid-sparing immunosuppressive agent. The most common complications were cataract (50%) and ocular hypertension (30%). The mean presenting best corrected visual acuity in the sympathizing eye was 1.15 ± 0.99 logarithm of the minimum angle of resolution (logMAR), which improved to 0.54 ± 1.00 logMAR following treatment. Visual outcome was good (6/12 or better) in 70% of the sympathizing eyes, and 3 of the exciting eyes in the current study had good visual outcomes after the treatment. Conclusions: Prompt and effective management with corticosteroid-sparing immunosuppressive therapy in children with sympathetic ophthalmia allows favorable control of the disease and retention of good visual acuity. [ J Pediatr Ophthalmol Strabismus . 2020;57(3):154–158.]

Precis Phacotrabeculectomy with adjunctive mitomycin C is a good option for the management of coexisting cataract and glaucoma. Strict preoperative control of inflammation and close follow-up are essential in the management of eyes with uveitic glaucoma (UG). Purpose The purpose of this study was to compare the outcomes of phacotrabeculectomy with adjunctive antimetabolites in the management of patients with UG and patients with primary open-angle glaucoma (POAG). Materials and methods A retrospective case-control study of 112 patients with UG and 120 patients with POAG who underwent phacotrabeculectomy with mitomycin C and had a follow-up of ≥12 months between January 2000 and June 2015 was performed. Patients who had undergone intraocular surgery or cyclodestructive procedures earlier were excluded. The primary outcome was intraocular pressure (IOP) control; secondary outcomes included visual acuity and complication rates. Results IOP control was similar at the final visit in the UG group (14.52±6.74 mm Hg) and the POAG group (14.39±4.18 mm Hg) (P=0.867). Kaplan-Meier survival analysis showed a cumulative probability of survival (IOP: 6 to 18 with or without medications) in 71% and 77% at the end of 5 years (P=0.094) in the UG and POAG groups, respectively. Visual outcomes were worse in the UG group (0.5±0.68 logMAR units), as compared with the POAG group (0.27±0.47 logMAR units) (P=0.002). Complications such as cystoid macular edema (P=0.025) and posterior capsular opacification (P=0.004) were more common in the UG group. Recurrence of inflammation occurred in 34 eyes (30.04%) in the UG group. Conclusion Meticulous control of perioperative and postoperative inflammation could have contributed to the favorable long-term outcomes of phacotrabeculectomy in UG, as compared with POAG.

Carbon-silicon alloys in different stoichiometric ratios are synthesized by delithiation of carbon-lithium-silicon ternary alloys with ethanol followed by washing with HCl and distilled water. The as-prepared carbon-silicon materials are air and water stable. In contrast to mechanically milled or sputtered C-Si alloys studied in the past, the method of synthesizing C-Si alloys introduced in this work avoids the formation of inactive SiC even after two hours high energy ball milling. This results in C-Si alloys with significantly greater volumetric and specific capacity. When cycled in Li half-cells, C-Si alloys exhibit good cycling performance and lower volume expansion compared to conventionally made Si alloys. This is attributed to the presence of void spaces in the structure which can accommodate some of the Si volume expansion.

To describe the clinical profile of HLA B-27-associated uveitis in Indian population. We conducted a retrospective review of medical records of 431 eyes of 255 consecutive patients with HLA B-27-associated uveitis, presented to our institute between 2012 and 2017. The study observed a male preponderance (75.7%) and the mean age of patients was 35.6 ± 13.3 years. A total of 412 (95.3%) eyes had anterior uveitis, 17(3.9%) eyes had anterior and intermediate uveitis and 3 eyes (0.7%) had intermediate uveitis. Retinal vasculitis was detected in four eyes (0.9%). A total of 176 patients (69%) in the study had evidence of systemic disease and 85% patients developed recurrences. In addition to the treatment with topical and oral steroid, immunosuppressive was required in 39.6% patients and 4% patients received biological therapy. The majority of the eyes (78.4%) had a good visual outcome, while 61 (14.2%) eyes had moderate visual impairment and 32 (7.4%) eyes had severe visual impairment at the time of final follow-up. HLA-B27-associated uveitis can be associated with higher number of posterior segment involvement than it is estimated and aggressive therapy in moderate-to-severe uveitis can prevent severe visual impairment in these patients.

Purpose: To describe the clinical pattern of scleritis in patients ≤16 years of age at a tertiary care eye hospital in India. Methods: The medical records of 24 eyes of 20 children with scleritis were included in this retrospective study. Collected data included age, subsets of uveitis, best corrected visual acuities (BCVA), detailed laboratory investigations and treatment. Results: Mean age at presentation was 12.2 ± 2.5 years. Scleritis was unilateral in 80% patients and an equal gender distribution was observed. Posterior scleritis (41.7%) was the most common subtypes of scleritis and nodular scleritis was the most common type of anterior scleritis (33.3%). Necrotizing scleritis was seen in 16.7% eyes. Tuberculosis was the only systemic association and found in three (15%) patients. Conclusions: Clinical profile of scleritis in children can be different from that of adults.

Purpose: To report the clinical profile of a series of antineutrophil cytoplasmic antibody (ANCA)-associated scleritis in Indian population. Methods: We conducted a retrospective review of medical records of 33 eyes of 26 consecutive patients with scleritis, who tested positive for either antibody to proteinase 3 [anti-PR3/cytoplasmic antineutrophil cytoplasmic antibody (cANCA)] or myeloperoxidase [anti-MPO/perinuclear anti-neutrophil cytoplasmic antibody (pANCA)] between 2006 and 2015. Results: The mean age at presentation was 54.1 (11.1) years and 61.5% of the patients were female. Underlying systemic disorder was found in 46.2% of patients and includes granulomatosis with polyangitis (30.8%) and tuberculosis (15.4%). Necrotizing scleritis (48.5%) was the most common scleritis observed, followed by diffuse anterior scleritis (42.4%). Positive cANCA was found in 65.4% of patients and 34.6% was found positive for pANCA. Four of the six patients with positive Mantoux test were started on anti-tuberculosis treatment (ATT) by pulmonologist. Cyclophosphamide was the most common immunosuppressive and 11.5% of the patients required combination of two immunosuppressives. Seventeen eyes developed cataract and four eyes required patch graft. Female gender was more frequently associated with pANCA-associated scleritis than cANCA (P = 0.037). Incidence of necrotizing scleritis was higher in patients with positive cANCA, but this difference was not statistically significant (P = 0.806). cANCA-positive patients had statistically significant higher association with systemic rheumatic diseases (P = 0.021). Conclusion: Necrotizing scleritis is the most common subtype of scleritis in ANCA-positive individuals and even in the absence of systemic involvement. All patients with ANCA positivity should be thoroughly screened to rule out any evidence of tuberculosis, especially in tuberculosis-endemic region before planning aggressive immunomodulatory therapy.

To describe clinical manifestations, management and visual outcome in postsurgical sympathetic ophthalmia (SO). Retrospective study. Mean age of the patients was 41.1 years, and males were affected 1.8 times than the female. Vitrectomy and scleral buckling were the most common inciting surgeries followed by cataract surgery. Among 10 eyes with anterior uveitis, mutton-fat keratic precipitate was seen in only two eyes. Mean follow-up duration was 1556.50 ± 1470.75 days. Vision significantly improved in 11 patients (78.6%; p = 0.005). Postsurgical SO is a rare entity, but it is a bilateral blinding disease and SO following surgical intervention can have variable presentations. Rapid, effective management of postsurgical sympathetic ophthalmia can give improved visual outcomes.

To describe the clinical pattern of uveitis in patients with retinitis pigmentosa (RP) at a tertiary care eye hospital over a period of 30 years.The medical records of 32 eyes of 22 patients of RP with uveitis were included in this study. Collected data included age, subsets of uveitis, best corrected visual acuities (BCVA), detailed laboratory investigations, and treatment.Mean age at presentation was 53.4 ± 18.8 years, and mean age of diagnosis of RP was 39.2 ± 21.4 years. Uveitis was bilateral in 10 (45.5%) patients. The most common of uveitis in current study was anterior uveitis (56.2%), followed by intermediate uveitis (43.8%). Cataract developed in 12 (37.5%) eyes, and three eyes had raised intraocular pressure. Ten patients (45.5%) required oral steroid, and one patient required oral methotrexate.Uveitis in RP patients is rare, but not uncommon. Coexistence of these disorders might support the inflammatory pathway in etiology of RP.

Macular hole is a defect in the neurosensory retina at the center of the fovea, seen in 8.3% of the postuveitic cases. In such cases, macular holes tend to be large and are associated with structural damage in the outer retinal layers. Here, we report a case of bilateral chronic intermediate uveitis treated with sub-Tenon steroids that developed a full-thickness macular hole in the right eye. We treated it surgically with inverted flap technique of internal limiting membrane peeling. Postoperatively, the patient showed Type-1 closure of the hole with visual improvement.

An international, expert led consensus initiative was set up by the Collaborative Ocular Tuberculosis Study (COTS) group to develop systematic, evidence, and experience-based recommendations for the treatment of ocular TB using a modified Delphi technique process. In the first round of Delphi, the group identified clinical scenarios pertinent to ocular TB based on five clinical phenotypes (anterior uveitis, intermediate uveitis, choroiditis, retinal vasculitis, and panuveitis). Using an interactive online questionnaires, guided by background knowledge from published literature, 486 consensus statements for initiating ATT were generated and deliberated amongst 81 global uveitis experts. The median score of five was considered reaching consensus for initiating ATT. The median score of four was tabled for deliberation through Delphi round 2 in a face-to-face meeting. This report describes the methodology adopted and followed through the consensus process, which help elucidate the guidelines for initiating ATT in patients with choroidal TB.

Editor,We thank Vergouwen et al. for their interest in our article.1 We also congratulate them for sharing their experience and concur with their data on recurrences of scleritis after cataract sur...

Purpose: To report early confirmation of Mycobacterium tuberculosis (MTB) endophthalmitis by detection of 85B mRNA in vitreous by a reverse transcriptase polymerase chain reaction (RT-PCR) technique.Methods: Retrospective, interventional case series of 5 patients with MTB endogenous endophthalmitis. Vitreous aspirate was subjected to Ziehl-Neelsen (ZN) staining, BACTEC MicroMGIT culture, RT-PCR targeting the 85B gene, real-time PCR targeting the IS6110 region, and nested PCR targeting the MPB64 gene and IS6110 region. Correlation between detection of MTB RNA, culture positivity, and ZN staining was studied.Results: Five patients with endophthalmitis with no history of tuberculosis revealed acid-fast bacilli on ZN staining of vitreous. RT-PCR detected 85B RNA within 24 h. Culture for MTB was positive in 3/5 patients after 1 month. None of the eyes recovered any useful vision.Conclusions: RT-PCR can detect viable MTB RNA and provide evidence of active infection much earlier than culture.

To analyse the prevalence, incidence, and risk factors of glaucoma in Vogt Koyanagi Harada (VKH) disease and study the changes in visual acuity and intraocular pressure (IOP) with treatment.Retrospective chart analysis of 448 eyes of 224 patients of Indian origin diagnosed with VKH disease from January 1990 to December 2013, who had a minimum follow-up of 3 months was performed.Seventy-one eyes (15.8%) developed sustained elevation in IOP. The prevalence of glaucoma at presentation was 15.8% and the cumulative incidence of glaucoma was 11.7%. The mechanisms of glaucoma were open-angle glaucoma in 46 eyes, (64.8%), angle closure in 21 eyes (29.6%), and of combined mechanisms in the remainder (4 eyes, 5.6%). Acute angle-closure crisis developed in 9 eyes (12.6%). Uveal effusion (odds ratio 9.47; confidence interval, 4.08-20.03) and increased number of recurrences (odds ratio 1.31; confidence interval, 1.13-1.53) were found to be significant risk factors for the development of glaucoma. Successful control of IOP was achieved in 64% at 12 months using medical/ laser treatment for glaucoma and was 50 % at 12 months following surgical management.Glaucoma is a frequent complication of uveitis in VKH disease. Presence of uveal effusion and increased number of recurrences of inflammation are significant risk factors.

Purpose: To report the diagnosis of a case of tubercular sclerouveitis, which masqueraded as an ocular tumor.Design: Case report.Methods: Retrospective medical chart review including serological, radiological, and histopathological investigative results.Results: A patient presented with recurrent episodes of sclerouveitis in his right eye. Serological investigations for infective and connective tissue disorders were negative. Radiological investigation was suggestive of a scleral perforation. The eye was enucleated and histopathological examination showed chronic inflammation. Polymerase chain reaction of the ocular tissue was positive for IS1160 for Mycobacterium tuberculosis.Conclusion: Infective scleritis should be suspected in cases of scleritis that progress despite treatment. Polymerase chain reaction is instrumental in diagnosing challenging cases.

Magnetostrictive rods of the approximate composition Fe82Ga18 have been produced with a preferred 〈1 0 0〉 axial crystallographic texture. Randomly oriented polycrystalline rods were cast by a suction extraction technique and a preferred 〈1 0 0〉 axial crystallographic texture was introduced through zone melting. Capacitance dilatometery showed that the as-cast rods and oriented zone-melted rods had saturation magnetostrictions of approximately 50 ppm and 100 ppm, respectively. Subsequent annealing of zone-melted rods resulted in a re-orientation of the axial crystallographic texture to a preferential 〈1 1 1〉 direction along with a corresponding reduction of the saturation magnetostriction.

Samples of Sn30TM30C40 and of Sn30Co15TM15C40, with TM = 3d transition metals, were prepared by vertical-axis attritor milling. The structure and performance of these samples were studied by X-ray diffraction (XRD) and by electrochemical testing. The XRD patterns of Sn30TM30C40 show an amorphous-like diffraction pattern only for the sample with TM = Co. The other prepared samples show broadened Bragg peaks of their main starting material, along with an amorphous-like background, even after 32 h of milling. Samples with TM = Co and TM = Ni show stable differential capacity versus potential plots and stable cycling for at least 100 cycles with reversible capacities of 425 and 250 mAh g−1, respectively. All samples prepared with 15 at.% Co show good capacity retention for at least 100 cycles ranging from 270 mAh g−1 for samples with TM = Ni to 500 mAh g−1 for samples with TM = Ti. The differential capacity versus potential plots for all the prepared Sn30Co15TM15C40 samples show similar structure to that of Sn30Co30C40 except when TM = Cu. This shows the possibility of preparing tin-based negative electrode materials using a combination of cobalt and TM, especially if one looks to reduce the cobalt content.

The purpose of this report was to evaluate the role anti-VEGF in management of CNVM secondary to ocular toxoplasmosis. Young female diagnosed as a case of bilateral ocular toxoplasmosis presented with complaints of diminution of vision in the right eye. Fundus examination showed an active CNVM adjacent to toxoplasmosis scar. In view of active CNVM, patient was administered intravitreal ranibizumab. A total of 2 injections of intravitreal ranibizumab were given. Fundus showed a scarred CNVM adjacent to the toxoplasma scar with no clinical signs of activity. Anti-VEGF therapy has been successfully used to improve visual and anatomical outcome in juxtafoveal (deleted subfoveal)CNVM secondary to toxoplasmosis.

Rotating a water-cooled substrate rapidly under Mo and Sn sputter sources made sequentially sputtered molybdenum–tin thin films. The layer thickness deposited during each circuit under each source was selected between 2 and 20 A and films of several micrometers overall thickness were prepared. The produced films were characterized using wide-angle and small-angle X-ray scattering, 119 Sn Mossbauer spectroscopy, differential scanning calorimetry and transmission electron microscopy. Films of three major types are observed: (1) homogeneous crystalline body centered cubic Mo 1− x Sn x is produced when x is less than approximately 0.45 and when the layer thickness deposited in each pass under the targets is small; (2) nanocrystalline BCC Mo 1− x Sn x having x approximately equal to 0.45 coexisting with nanocrystalline tin when the overall tin content is greater than 45% atomic and the layer thickness deposited in each pass under the targets is small; and (3) lamina of composition modulated Mo 1− x Sn x disturbed by nanoscopic clusters of tin when the overall tin content is greater than approximately 40% atomic and the layer thickness of Mo deposited in each pass is greater than approximately 6 A. This is the first report of BCC Mo 1− x Sn x for 0≤ x ≤0.45. A ‘phase diagram’ of the observed film types is presented.

The spectrum of ocular lesions in children with HIV infection is different from that seen in adults. Ocular lesions in pediatric AIDS patients have not been studied in India. We analyzed the clinical profile, demographic characteristics, ocular and systemic lesions in children with AIDS seen in a referral eye institute in India. The clinical profile and demographic features were studied and complete ocular examination was done. Systemic findings were evaluated at an AIDS care center and recorded in a precoded proforma. Out of the 218 cases of HIV infection seen at our hospital between December 1993 and October 1999, 12 (5.50%) were below 15 years of age. Seven (58.33%) were males and 5 (41.66%) were females with the mean age of 6.5 years and median age of 6.2 years. Vertical transmission was the most common mode of infection (58.33%). Seven (58.33%) of these patients had systemic infection, the most common being pulmonary tuberculosis (42.85%). Ocular lesions were found in 6 (50%) patients. The most common ocular lesions were anterior uveitis and cytomegalovirus retinitis (CMV) (33%) followed by retinal detachment (16.66%) and vitreous hemorrhage (16.66%). High prevalence of ocular lesions in pediatric AIDS patients in India in a referral eye centre was observed. The most common lesions were anterior uveitis followed by CMV retinitis. The management in such cases was often challenging in a developing country like India.

PURPOSE: To document the ocular disorders seen in patients known to be infected with human immunodeficiency (HIV) virus at a referral eye clinic in India. METHODS: The first 100 individuals known to be HIV-positive at a referral eye clinic between 1993 and 1998 were enrolled in a prospective study. They underwent complete ocular and systemic evaluation. RESULTS: Most of the patients (76%) were in the 20- to 40-year age group. Heterosexual exposure to commercial sex workers was the most common risk factor. See also pp. 1–8. (70%) for HIV infection. Cytomegalovirus (CMV) retinitis (17%) and HIV retinopathy (15%) were the most common HIV-associated ophthalmic lesions. Pulmonary tuberculosis (67%) and oropharyngeal candidiasis (66%) were the most commonly associated systemic infections. Ocular involvement was most common in children who contracted the disease through perinatal transmission (66.7%) and in homosexual patients (60%). Ocular involvement was comparatively less common in patients who contracted the disease through blood transfusions (33%) or exposure to commercial sex workers (24.3%). CONCLUSIONS: This study shows that the spectrum of ocular lesions associated with HIV infection in India is different from that seen elsewhere in the world. The prevalence of CMV retinitis and HIV retinopathy is lower in India, and there have been no cases of ocular Kaposi sarcoma. Adnexal infections, albeit rare, were seen in our series. The nonavailability and cost of therapy influenced the visual prognosis in these patients.

A series of samples pyrolysed to different temperatures were synthesized from dewatered sucrose. These samples were characterised by wide-angle X-Ray scattering (WAXS), small-angle X-Ray scattering (SAXS), BET surface area and CO2 gas adsorption measurements. WAXS and SAXS measurements were used to determine the average number of graphene sheets stacked in a parallel fashion and the average micropore size (8–10 A in radius), respectively. As the heat treatment temperature (HTT) was increased, WAXS and SAXS measurements show that the internal structure of these materials is changing in a fashion consistent with the falling card model. CO2 gas adsorption measurements show that the micropores in the sample are closing, forming an intermediate partially closed micropore, with increasing HTT (predominantly in the range 900–1400°C). A model of micropore closure is presented that describes the number of open micropores as a function of the heat treatment temperature and exposure time. A simple adsorption model based on the Langmuir equation is presented and was used to determine the number of open micropores in the sample.

"Non‐graphitizable" or "hard" carbon anode materials have almost twice the capacity (per unit mass) of graphitic materials that currently represent the industrial standard for Li‐ion batteries. One problem with hard carbon is the small hysteresis in the voltage profile between charge and discharge. This small hysteresis has been correlated to residual hydrogen content after pyrolysis (

The objective of this study was to identify suitable combinations of additives to aqueous alkaline formulations for the potential recovery of Saskatchewan heavy crude oil. A previously developed strategy was applied to screen various additive combinations consisting of three commercial petroleum sulfonate surfactants and two commercial lignosulfonate surfactants. The selection of the additives was based on a large number of physical and interfacial property measurements in conjunction with phase stability tests at different temperatures. The resulting ternary formulations, labelled here as Mixed-Surfactant-Enhanced Alkaline (MSEA) systems, were very successful in reversing the trend of increasing interfacial tension with time that characterizes additive-free alkaline/crude oil systems. This success came at the expense of initial IFT values that were considerably higher than those exhibited by the corresponding additive-free alkaline solutions. However, at higher temperatures (65 °C), these ternary MSEA formulations were capable of generating very low IFT values against the crude oil (in the range of 5 × 10−2 to 10−1 mN/m), which suggests that they could be suitable candidates for commercial exploitation of heavy oil recovery processes. Cette etude a pour objectif de determiner des combinaisons adequates d'additifs pour des formulations alcalines aqueuses en vue de la recuperation potentielle d'huile lourde de Saskatchewan. On a utilise une strategie mise au point anterieurement pour filtrer diverses combinaisons d'additifs constituees de surfactants commerciaux, dont trois au sulfonate de petrole et deux au lignosulfonate. La selection des additifs a ete effectuee a partir d'un grand nombre de mesures des proprietes physiques et interfaciales conjointement a des tests de stabilite des phases a differentes temperatures. Les formulations ternaires qui en resultent, designees ici sous le nom de systemes alcalins melanges enrichis en surfactants (MSEA), ont permis facilement de renverser l'augmentation de la tension interfaciale dans le temps, une tendance qui caracterise les systemes sans additifs alcalins-huile lourde. Ce succes a ete obtenu au depens des valeurs initiates de la tension interfaciale qui etaient considerablement plus grandes que celles des solutions alcalines avec additifs correspondantes. Toutefois, a des temperatures elevees (65°C), ces formulations ternaires MSEA ont ete capables de creer de tres faibles valeurs de tension interfaciale par rapport a l'huile lourde (comprises entre 5 × 10−2 et 10−1 mN/m), ce qui suggere qu'elles pourraient etre utilisees pour l'exploitation commerciale des procedes de recuperation de l'huile lourde.

Abstract Horizontal wells have been shown to be successful in improving oil recovery for marginal heavy oil reservoirs in Saskatchewan and Alberta. One commonly encountered problem in recovery operations for these unconsolidated reservoirs is the production of sand and fines. The settling and accumulation of the solid particles inside the horizontal wellbore represents a serious problem, with the horizontal well becoming partially plugged being a real possibility. This study investigates this problem, with focus on determining the roles played by different flow parameters on the settling and transport process. The physical model described in this work examines the transport process mechanistically. Conservation equations for the solid phase (sand particles) and the fluid phase (oil) are formulated, with the interaction between the phases described by empirical correlations. The oil is assumed to be a Newtonian fluid, and the sand particles are assumed to be spherical in shape and uniform in size. The system of equations is solved numerically to determine the distribution of sand particles and oil, and the respective pressure and velocity distributions as a result of the presence of a constriction inside the horizontal well. According to the simulation results, oil viscosity and particle size play important roles in the transport process, including controlling the gravitational settling tendency of solid particles inside the horizontal wellbore. The results provide insight into the mechanisms involved in the transport process; as such, they provide guidelines for production operations involving horizontal wells in unconsolidated and poorly consolidated reservoirs. Introduction One of the most common applications of horizontal well technology in Canada is to recover oil from heavy oil reservoirs in Saskatchewan and Alberta. In heavy oil reservoirs underlain with bottom-water, the use of horizontal wells has been found to improve primary recovery performance prior to water coning - recovering up to 15% of the initial oil in place (in shorter time, also), compared with only 5% for a vertical well. Horizontal wells have also been successfully used for increasing steamflood recovery. However, recovery operations in these heavy oil reservoirs are usually susceptible to sand production due to their unconsolidated nature. The produced sand could give rise to production problems. as the sand fill up the wellbore, prevent the operations of downhole pumps, etc. In the case of horizontal wells, sand production potentially poses an even more serious problem, due to the settlement and accumulation of sand particles at different positions along the well - leading to the reduction of the cross-sectional area of the wellbore open to flow (Figure 1). The ultimate effect of sand deposition could be the partitioning of the horizontal well into several segments, leading to a loss of production and a negation of the principal advantage of horizontal wells (large contact area with the reservoir). The study reported here investigates this problem. Specifically the study examines, through numerical simulation, the transport and distribution of sand particles, pressure, and velocity distributions in a horizontal well. A special feature of the physical model is the presence of a constriction inside the horizontal well. Solid-liquid flow encompasses many different areas of science and engineering, including the transport of colloids in rain water, sediment transport in river streams, slurry pipeline transportation, drill cuttings removal, transport of proppants in hydraulically fractured wells, etc. The large number of independent variables involved in these transport processes, coupled with the complex interaction between the variables have precluded comprehensive analytical studies of these processes mechanistically. Instead, many experimental studies have been carried out over the years. P. 471^

Abstract Canada's heavy oil and oil sands deposits are estimated to contain as much oil as the conventional oil resources of the entire world. Heavy oil deposits, in particular those in southwestern Saskatchewan and southeastern Alberta, represent an attractive target for exploitation as the in-place heavy oils are mobile under reservoir conditions. These reservoirs typically have good porosity, high permeability (1–5 darcies), high initial oil saturation >65%), and the oil viscosity ranges from 1000 to 1500 cp; but the pay thickness is between 3–10 metres and often underlain by bottom water zone ("bottom water"). Primary recovery in these reservoirs typically amounts to less than 5% of the initial oil in place (IOIP). In a few cases, where the conditions are more favorable, use of horizontal wells has increased primary recovery to 15-20% prior to water coning. This still leaves up to 80% of the oil in place unrecovered. Using a scaled physical model of the Aberfeldy reservoir (Saskatchewan), steamflood experiments were performed to investigate steamflood recovery performance using horizontal injection and production wells. This paper reports results of analyses made for two types of experiments; one was for steamflooding a homogeneous reservoir (base case run), and the other was for steamflooding a reservoir having a 20% net pay bottom water layer. Analyses include comparisons between steam zone volumes obtained experimentally and theoretically, and heat distribution (heat injected, heat loss, heat accumulated, and heat produced) during a steamflood The scale up of laboratory results to predict prototype field performance is also presented. The analytical heat loss model, based on the simultaneous solution of two heat conduction equations, showed a 3.1% difference from experimental results. Scaled-up experimental data, for the base case run (horizontal injector and producer), showed that approximately 20% of the initial oil in place (IOIP) was recovered after 0.8 PV of steam (CWE) had been injected. For a reservoir having a 20% net pay bottom water, after 0.8 PV of steam (CWE) had been injected, heat accumulated in the formation was found to be approximately 3776.6 kJ. Of this, 2000 kJ of energy was stored in the matrix, and the fluids in the reservoir contained 1776.6 kJ of energy. The increase in the oil recovery for a reservoir having 20% net-pay bottom water layer depends on how the energy contained in the fluids is managed Introduction Over 20 billion barrels of oil are contained in the marginal heavy oil reservoirs of Saskatchewan and Alberta. These reservoirs are thin (3–10 meters of pay) and often in communication with an underlying water zone. Cyclic steam stimulation and steamflooding operations using vertical wells have proven uneconomic in these reservoirs, mainly due to excessive channeling of steam. On the other hand, horizontal wells have been shown to be capable of improving steamflood recovery performance, due to their extended contact with the reservoir and their ability to improve sweep efficiency (due to a delay in steam override, and minimizing effect of heat loss to the cap/base rock). This study attempts to provide insight into the performance prediction of steamflooding a marginal heavy oil reservoir using horizontal injection and production wells, and looks at different steamflooding strategies for improving recovery. These objectives were achieved experimentally using a scaled physical model, and a visual unscaled model. P. 93^

Abstract Horizontal wells have been used successfully in Canada to recover oil from marginal heavy oil reservoirs in Saskatchewan and Alberta. These reservoirs are often poorly consolidated; recovery operations in these reservoirs are, therefore, usually susceptible to sand production. A horizontal well could be partially blocked due to the deposition and accumulation of sand particles inside the wellbore. This study presents a mathematical treatment of the transport process of oil and sand particles inside a constricted horizontal well. The model described in this paper formulates the transport process mechanistically. Continuum assumption is made for the fluid phase (oil) as well as the solid phase (sand particles). Equations of mass and momentum conservation for the solid phase and the fluid phase are formulated. The oil is assumed to be Newtonian, and the sand particles are assumed to be spherical in shape and uniform in size. The model incorporates empirical correlations to describe the interaction between the two phases. The system of equations is solved numerically to determine the transient distribution of sand particles and oil, and their pressure and velocity distributions as a result of an expanding constriction inside the horizontal well. Numerical simulation results provided insight into the mechanisms involved in the transport process, thus enhancing the understanding of the flow of sand and oil inside a horizontal well. Introduction One of the most common applications of horizontal well technology in Canada is to recover oil from heavy oil reservoirs in Saskatchewan and Alberta. In heavy oil reservoirs underlain with bottom-water, the use of horizontal wells has been found to improve primary recovery performance prior to water coning, recovering up to 15% of the initial oil in place compared with only 5% for a vertical well(1). The recovery rate is also increased. Horizontal wells have also been successfully used for increasing steamflood recovery(2, 3). However, recovery operations in these heavy oil reservoirs are usually susceptible to sand production due to their unconsolidated nature. The produced sand could give rise to production problems, as the sand fill up the wellbore, prevent the operations of downhole pumps, etc.(4). In the case of horizontal wells, sand production potentially poses an even more serious problem, due to the settlement and accumulation of sand particles at different positions along the well, leading to the reduction of the cross-sectional area of the wellbore open to flow (Figure 1). The ultimate effect of sand deposition could be the partitioning of the horizontal well into several segments, leading to a loss of production and a negation of the principal advantage of horizontal wells (large contact area with the reservoir). The study reported here investigates this problem. Specifically the study examines, through numerical simulation, the transport and distribution of sand particles, and pressure, and velocity distributions in a horizontal well. A special feature of the model is the presence of a constriction inside the horizontal well.

An important application of horizontal well technology in Canada is recovering oil from marginal heavy oil reservoirs in Saskatchewan and Alberta. These reservoirs are often poorly consolidated ; as a result, recovery operations are susceptible to sand production which potentially poses a serious problem as the sand particles deposit and partially block the horizontal well. This work presents a mathematical treatment of the transport process of oil and sand particles inside a horizontal well. In particular, the model described in this paper formulates the transport process mechanistically. Equations of mass and momentum conservation for the solid phase (sand particles) and the fluid phase (oil) are formulated. The oil is assumed to be Newtonian, and the sand particles are assumed to be spherical in shape and uniform in size. In addition, the model incorporates empirical correlations to describe the interaction between the two phases. The system of equations is solved numerically to determine the distribution of sand particles and oil, their pressure and velocity distributions as a result of the presence of a constriction inside the horizontal well. Simulation results obtained provide insight into the mechanisms involved in the transport process, thus enhance the understanding of the flow of sand and oil inside a horizontal well. This, in tum, yields some guidelines for production operations involving horizontal wells in unconsolidated and poorly consolidated reservoirs.

Background Ocular lesions in patients on highly active antiretroviral therapy (HAART) have shown changes in disease prevalence and pattern. Although they have been described in the Western population, there are not many such studies in the HAART era from India. This study aims to present the clinical profile, systemic correlation, and visual outcome in HIV-positive patients in relation to HAART in comparison with pre-HAART Indian studies and current Western data. Ocular findings and systemic correlation in 1,000 consecutive patients with HIV seen at a tertiary eye care center were analyzed. This study uses a prospective observational case series design. Results Age range of the patients was 1.5 to 75 years. Ocular lesions were seen in 68.5% of the patients (cytomegalovirus (CMV) retinitis was the commonest). The commonest systemic disease was pulmonary TB. Mean interval between HIV diagnosis and onset of ocular lesions was 2.43 years. CD4 counts range from 2 to 1,110 cells/mm3. Immune recovery uveitis (IRU) was seen in 17.4%. Interval between HAART initiation and IRU was 4 months to 2.5 years. Recurrence of ocular infection was seen in 2.53% (post-HAART) and > 20% (pre-HAART). Overall visual outcome showed improvement in about 14.3% and was maintained in 71.6% of the patients. Conclusions CMV retinitis is the commonest ocular opportunistic infection in India, even in the HAART era. Newer manifestations of known diseases and newer ocular lesions are being seen. In contrast to Western studies, in our patients on HAART, ocular lesions do not always behave as in immunocompetent individuals. Ocular TB needs to be kept in mind in India, as well as other neuro-ophthalmic manifestations related to cryptococci, especially in gravely ill patients. Occurrence and frequency of various ocular opportunistic infections in developing nations such as India have significant variations from those reported in Western literature and need to be managed accordingly.

Abstract The feasibility of employing various alkaline agents (sodium hydroxide, sodium metasilicate and sodium orthosilicate) to enhance the recovery of a specific Saskatchewan heavy oil from the Kindersley region has been investigated. The dynamic interfacial tension behaviors of solutions of these alkalis in contact with the crude oil were measured for a range of concentrations and temperatures, and the most interfacially active formulations were then tested for their oil recovery efficacies by conducting oil displacement experiments in unconsolidated linear sand packs at 25 °C and 65 °C. The most promising of the three alkalis tested was found to be sodium hydroxide, which was capable of producing very significant enhancements in oil recovery relative to that obtained with pure waterflooding. Introduction The so-called heavy oil belt of Saskatchewan covers a wide area that stretches from Lloydminster in the north to Kindersley in the south. The estimated ultimate oil in place amounts to some 4 × 109 m3. In a recent appraisal of this huge reserve, Reid(1) suggested that 20% of the oil in place could be recovered by using enhanced oil recovery techniques. To date, only thermal processes such as in-situ combustion and steamflooding/stimulation are being applied to these reservoirs. However, since the density of the crude ranges from 11 to 20 °API and since the average temperature of these reservoirs is about 20 °C, the viscosity of the crude at reservoir conditions will be of the order of 1000 mPa.s or higher. Another significant characteristic of these deposits is the occurrence of the oil in relatively thin zones. According to Selby et al.(2), the thinness of the formations coupled with the large depths and low permeabilities makes thermal processes unsuitable for about 50% of the heavy oil deposits of Canada, the U.S. and Venezuela. Amongst the various non-thermal processes, alkaline flooding appears to be the most attractive. Alkaline reagents are abundant and quite cheap compared with conventional surfactants. Their effectiveness for the recovery of acidic crudes has been known since 1927 by virtue of the work of Nutting(3) and Atkinson(4). It is now generally accepted(5–8) that alkaline reagents react with surface active materials present in the crude resulting in the in-situ formation of surfactant soap species. The adsorption of these generated surfactants at the oil/water/sand interfaces often results in a drastic reduction of the interfacial tension and/or in a change in matrix wettability. The end result is the mobilization of residual oil trapped in the fine pores of the reservoir sand. Selby et al.(2) listed 15 recent field alkaline flood tests in Canada and the U.S. However, only one of those tests was considered successful, while the majority were abandoned. One reason for this dismal performance is the inadequate understanding of the complex interactions that occur between alkaline reagents, crude oil, formation water and matrix minerals. Even basic oil-water interfacial tension (IFT) behavior becomes very complex when dealing with crude oil/caustic systems. Several researchers(9,10) have reported variations in IFT of one or more orders of magnitude when crude oil was contacted with caustic solutions for contact times ranging between 10 and 60 minutes.

Abstract This paper examines the effects of in situ formation of a non-aqueous foam on flow of oil-gas mixtures in porous media. A laboratory technique to investigate the role of foamy-oil behaviour in solution gas drive is described and experimental verification of the in situ formation of non-aqueous foams under solution gas drive condition is presented. The experimental results show that the in situ formation of non-aqueous foam retards the formation of a continuous gas phase and dramatically increases the apparent trapped gas saturation. This provides the natural pressure maintenance mechanism and leads to recovery of a much higher fraction of the Original oil in place under solution gas drive. Introduction Several heavy-oil reservoirs in Alberta and Saskatchewan, show "foamy-oil" behaviour in wellhead samples produced under solution gas drive. The oil is produced in the form of an oil-continuous foam which has the appearance of chocolate mousse and contains a high volume fraction of gas. This foam can be quite stale and may persist for several hours in open-vessels. The field production data from these reservoirs suggests that the production mechanisms are complex and may be quite different from those encountered in conventional solutions-gas driven reservoirs. Several of these reservoirs show anomalously high production. Both the rate of production and the total recovery under solution Gas drive are much higher than what would be expected from measured oil parameters. History matching primary production For these wells often requires unrealistic adjustment of measured parameters, such as increasing the absolute permeability by an order of magnitude. In a recent publication, Longhead and Satroklaroglu(1) have described the unusual primary production behaviour of Celtic Field reporting that the rate of production in some wells is more than ten times the calculated pseudo-steady state oil flow rate under radial flow conditions. To obtain a satisfactory history match of the primary production behaviour, they had to assume very unusual reservoir properties. These included not only an artificially high absolute permeability but also a trapped gas saturation of 35% and an unusual oil relative permeability curve. These high productivity wells produce from unconsolidated sands, and a large volume of sand is produced with the oil. Generally any attempt to stop sand production results in drastically reduced production. Another part of this puzzle is that several of these wells, which are prolific in primary production, show very poor response to steam stimulation. Several possible causes of this anomalous production behaviour have been suggested and are being investigated. These include formation of worm holes around the well which increase the effective well radius(2). Sand dilation due to removal of substantial volumes of sand with the oil, resulting in increased absolute permeability appears to be another mechanism(1). The enhancement of oil mobility by nucleation of a large number of microbubbles has been suggested as another possibility(3, 4). Another possible cause of the anomalous behaviour is the in situ formation of an oil-continuous foam. It is likely that several of these mechanisms might be involved in varying degrees in different reservoirs.

Abstract Horizontal wells are gaining increased prominence in primary recovery and steam injection, yet experimental and theoretical modelling of horizontal wells is still inadequate. This paper explores these two areas. Equations were developed for three-phase and non-isothermal flow in the vicinity of a horizontal well, as well as flow inside the well. These were used to obtain scaling criteria for designing laboratory experiments. The question of skin factor due to perforated casing is also considered. An interesting idea offered is the use of variable diameter horizontal wells. A series of steam injection experiments was carried out in a model, with a concentric well. Temperature distributions were determined and used to interpret oil recoveries and pressure behaviour. Oil recovery performance for different experiments was evaluated to determine the effectiveness of different types of horizontal wells, and the impact of perforated casing. Introduction It has been reported extensively(1,2) that horizontal wells offer prospects of improved performance over conventional vertical wells, primarily due to the larger contact area between the formation and the horizontal well. This is especially true for thin oil formations where the reservoir contact area for a horizontal well can be hundreds of times that for a fully-penetrating vertical well, Furthermore, horizontal wells, when strategically placed, can reduce water/gas coning and result in improved cumulative recovery in view of the small draw downs(3). Horizontal wells are also believed to have a much better chance than vertical wells of intersecting systems of vertical and horizontal fractures in an oil-bearing formation, and thus lead to higher production rates(4). In steam injection recovery of heavy oils and oil sands horizontal wells especially when combined with steam-assisted gravity drainage could lead to high production rates, more uniform distribution of steam front leading to improved sweep efficiency and cumulative oil recovery(5,6). One aspect that has so far received little attention in discussions of horizontal well performance concerns the flow in the vicinity of, and inside a horizontal well. Often, it has been assumed that a horizontal well has infinite conductivity and that the flow in the well is predominantly laminar - meaning the pressure drop across [he well is not significant. Dikken(7) showed that this assumption is not necessarily true for most practical situations, and that pressure drops across horizontal wells can significantly affect the performance. This paper attempts to contribute to an understanding of this aspect of horizontal wells by presenting mathematical models of flow in the vicinity of, and inside a horizontal wellbore. These models were used to obtain scaling criteria for a series of scaled model steam injection experiments. Data, including well pressure drop and fluid production rates in the presence of a perforated casing are also reported. Literature Review Butler, McNab, and Lo(5) presented the first theoretical and experimental study of steam-assisted gravity drainage and horizontal wells to recover bitumen from oil sands. Equations were derived to calculate oil drainage rate and lateral position of steam-oil interface as functions of time and height. A subsequent study by Butler and co-workers(H) introduced improvements to the original model.

Abstract In Alberta and Saskatchewan, many heavy oil formations have a communicating high water saturation zone, which makes the use of conventional oil recovery methods unattractive. Often, attempts to produce such marginal oil reservoirs result in excessive water production due to coning and steam migration into the bottom water zone. Waterflooding is ineffective because of the high mobility ratio of water to heavy oil. This paper discusses recovery strategies and reservoir situations under which a steamflood can be conducted efficiently. A heavy oil reservoir in Saskatchewan was selected as the prototype for the scaled model steamflooding experiments. Four combinations of vertical and horizontal wells (injectors and producers) and two bottom water thicknesses were used. In one series of runs, the use of a small volume of solvent with steam was examined, with a view to divert steam early from the water zone. The results showed that the horizontal injector-horizontal producer combination recovered 68% of the oil in the presence of 10% thickness of high water saturation. In the absence of bottom water, the horizontal combination was only slightly better than vertical wells. With thicker bottom water zones (50% of model thickness), the oil recovery fell about 20% in all four cases. A 10% PV solvent slug injected ahead of steam improved oil recovery by only 5%. Guidelines are offered for steamflooding similar heavy oil reservoirs. Introduction Many heavy oil formations in the Lloydminster area of Saskatchewan and in eastern Alberta, classified as "marginal reservoirs" are becoming the focus of the current technology. Marginal reservoirs are characterized by a relatively thin pay (6 m to 13 m) with a high water saturation zone beneath the oil zone. The water zone, which is often in communication with the oil zone, can be either a transition zone or else a zone of high water saturation that can approach 100%. It may even be an active water aquifer. While low recoveries and poor sweep are attributed to the tendency of injected fluid to migrate through the path of least resistance via the bottom water zone, it is believed that the bottom water zone can also serve as a means for providing initial injectivity for a very viscous oil. A scaled physical model of the Aberfeldy heavy oil reservoir, in Lloydminster, was constructed according to the low-pressure scaling criteria developed by Stegemeier, Laumbach and Volek(1). These criteria were extended to include the case of solvent injection(2). Steamfloods incorporating various vertical and horizontal well combinations were conducted in the low-pressure model in order to determine optimum production strategies for bottom water reservoirs. Homogeneous (no bottom water), thin bottom water (10%), and thick bottom water (50%) cases were examined. In addition, the effect of solvent injection prior to steam injection in a thin bottom water formation was also investigated as an adjunct to the study. This paper discusses the results of the above experiments, suggesting strategies which may permit the economic production of a marginal heavy oil reservoir.

Abstract Steamflooding with horizontal wells promises to be a highly effective method for recovering heavy oils from shallow, thin formations. As is often the case for poorly consolidated heavy oil formations, sand production could constitute a serious production engineering problem. For horizontal wells, this problem could be exacerbated as the sands/formation fines could settle inside, and choke off sections of a horizontal well completely - leading to loss of production. To alleviate this problem, it is often necessary to case the horizontal wells. This paper reports results of a series of scaled model steam injection experiments investigating the role of a perforated casing on the recovery performance. Fluid production rate, well pressure drop, cumulative oil recovery and cumulative oil-steam ratio for open and cased horizontal wells are determined and compared to determine the impact of the casing. It is concluded that a casing, though necessary to control sand production into a horizontal well, could lead 10 lower cumulative oil recovery and lower thermal efficiency for the recovery process. For example. oil recovery and the cumulative oil-steam ratio in the absence of a casing were 49.7% of IOIP and 0.62, respectively. The corresponding values in the presence of a casing were 42.9% and 055, respectively. Introduction With innovations in lateral and horizontal drilling technology, more horizontal wells are being used to recover oil and gas world-wide. It has been widely recognized that the main advantages of horizontal wells over conventional vertical wells include larger reservoir contact area, ability to reduce the effects of gas/water coning, as well as the higher probability to intersect systems of vertical fractures in fractured reservoirs. In thermal recovery applications, horizontal wells - due to their extended contact with the reservoir - promise high production rates and improved steam sweep efficiency. For these reasons, many thermal horizontal well projects have been started up, and field-tested in Alberta and Saskatchewan 1–3. The main production mechanism for the AOSTRA Underground Test Facility (UTF) in Fort McMurray, Alberta is steam-assisted gravity drainage. The pilot has been so successful that an expanded Phase B which involves more and longer horizontal wells is being implemented for commercial operation 1. For Esso Canada Resources Ltd. 's Cold Lake horizontal well project, the first phase of operation involves cyclic steam stimulation of vertical wells to provide steam injectivity. Steam is then injected down these vertical injectors to push oil towards the horizontal producer 2. Scepcre Resources Ltd.'s North Tangleflags, Saskatchewan pilot 3 also utilizes vertical steam injectors to mobilize and displace the heavy oil into a long horizontal producer. Sand production is perhaps the most widespread and costly production problem associated with many thermal recovery projects. The sand and formation fines could either impair production by choking the wellbore or reduce production by preventing the proper operation of downhole pumping equipment. Also, they will require the replacement of equipment because of erosion damage 4.

Abstract Saskatchewan's proven reserve of heavy oil is estimated at 4 billion m3. About 20% of this reserve is recoverable by enhanced recovery processes. Thermal processes such as steam flooding and in situ combustion are the techniques most frequently used for these relatively cold reservoirs that contain very viscous oils. Since most of the oil occurs in rather thin formations, severe heat losses to adjacent rock strata would invariably reduce the effectiveness of thermal processes. On the other hand, chemical processes such as alkaline waterflooding have proved quite successful in laboratory tests. A properly formulated alkaline flood is expected to be more efficient and cost effective. A variant of the conventional alkaline flood is being proposed for these reservoirs, particularly for those that contain crudes with API gravities above 15. In this modified scheme, a hot alkaline formulation is used to reduce the oil viscosity. At the same time, the viscosity of the alkaline solution is considerably increased by the addition of thickening agents. In this paper we present a methodology which can be used to screen several alkaline reagents to determine the type and concentration appropriate for a target reservoir. Dynamic interfacial tension data and comparative oil recovery data from linear displacement tests are discussed. Introduction The so-called heavy oil belt of Saskatchewan covers a wide area that stretches from Lloydminster in the north to Kindersley in the south. The estimated ultimate oil in place amounts to 4 billion m3. In a recent appraisal of this huge reserve, Reid[l] suggested that 20% of the oil in place could be recovered by using enhanced oil recovery (EOR) techniques. To date, only thermal processes which include in-situ combustion and steamflooding/stimulation are being applied to these reservoirs. However, since the density of the crude ranges from 11 to 20 °API and since the average temperature of these reservoirs is about 20 °C, the viscosity of the crude at reservoir conditions will be 1000 mPa.s or higher. Another significant characteristic of these deposits is the occurrence of the oil in zones of relatively thin sands. According to Selby et a1[2], the thinness of the formations coupled with the large depths and low permeabilities makes thermal processes unsuitable for about 50% of the heavy oil deposits of Canada, the U.S. and Venezuela. Among the various non-thermal processes, alkaline flooding appears to be the most attractive. Alkaline reagents are abundant and quite cheap compared with conventional surfactants. Their effectiveness for the recovery of acidic crudes has in fact been known since 1927 by virtue of the work of Nutting[3] and Atkinson [4] . It is now generally accepted[5-8] that alkaline reagents react with surface active materials present in the crude resulting in the in situ formation of surfactant soap species. The adsorption of these in situ generated surfactants at the oil/water/sand interface may result in a drastic reduction of the interfacial tension and/or a change in matrix wettability. The end result is the mobilization of residual oil trapped in the fine pores of the reservoir sand.

To develop effective utilization technology for heavy streams from conventional fuels and unconventional resources such as heavy oils and oilsand bitumens, detailed information on the chemical composition of the feedstocks is needed. Attempts were made during the seventies to modify the API Project 60 scheme of analysis or to develop chemically more efficient, and less time-consuming, separation and characterization methods. These attempts aimed to improve characterization by separating the samples into concentrates of different structural types. Samples throughput was increased by using pressure and higher performance chromatographic systems. Other valuable contributions, such as coal-liquid characterization in terms of different chemical functionalities have also been made. The separation of aromatic ring classes and characterization or identification of their major components was our primary objective in this study. A silica-R(NH/sub 2/)/sub 2/-based HPLC system was used in our laboratory to study the analytical potential of this approach; the work was described in a previous publication. In the present study, the applicability of HPLC separation by this system and instrumental spectrometric characterization of 3- and 4-ring PAHs isolated from two Canadian oils were investigated. The oils used, Medicine River and Lloydminster, are examples of hydrocarbon-dominated materials representing light and heavy processing feedstocks, respectively.

INTERPRETIVE abstracts of all papers definitely scheduled for presentation at the A.I.E.E. summer convention (June 26–30, 1933) are published herewith, excepting only those papers published in this issue of ELECTRICAL ENGINEERING.