An approximate solution of the MHD Falkner-Skan flow by Hermite functions pseudospectral method

Based on a new approximation method, namely pseudospectral method, a solution for the three order nonlinear ordinary differential laminar boundary layer Falkner-Skan equation has been obtained on the semi-infinite domain. The proposed approach is equipped by the orthogonal Hermite functions that have perfect properties to achieve this goal. This method solves the problem on the semi-infinite domain without truncating it to a finite domain and transforming domain of the problem to a finite domain. In addition, this method reduces solution of the problem to solution of a system of algebraic equations. We also present the comparison of this work with numerical results and show that the present method is applicable.Comment: 15 pages, 4 figures; Published online in the journal of "Communications in Nonlinear Science and Numerical Simulation

An approximation algorithm for the solution of the nonlinear Lane-Emden type equations arising in astrophysics using Hermite functions collocation method

In this paper we propose a collocation method for solving some well-known classes of Lane-Emden type equations which are nonlinear ordinary differential equations on the semi-infinite domain. They are categorized as singular initial value problems. The proposed approach is based on a Hermite function collocation (HFC) method. To illustrate the reliability of the method, some special cases of the equations are solved as test examples. The new method reduces the solution of a problem to the solution of a system of algebraic equations. Hermite functions have prefect properties that make them useful to achieve this goal. We compare the present work with some well-known results and show that the new method is efficient and applicable.Comment: 34 pages, 13 figures, Published in "Computer Physics Communications

Investigation of Primary Recovery in Low-Permeability Oil Formations: A Look at the Cardium Formation, Alberta (Canada)

Tight oil formations (permeability < 1 mD) in Western Canada have recently emerged as a reliable resource of light oil supply owing to the use of multifractured horizontal wells. The Cardium formation, which contains 25% of Alberta’s total discovered light oil (according to Alberta Energy Resources Conservation Board), consists of conventional and unconventional (low-permeability or tight) play areas. The conventional play areas have been developed since 1957. Contrarily, the development of unconventional play is a recent event, due to considerably poorer reservoir properties which increases the risk associated with capital investment. This in turn implies the need for a comprehensive and critical study of the area before planning any development strategy. This paper presents performance results from the low permeability portions of the Cardium formation where new horizontal wells have been drilled and stimulated in multiple stages to promote transverse hydraulic fractures. Development of the tight Cardium formation using primary recovery is considered. The production data of these wells was first matched using a black oil simulator. The calibrated model presented was used for performance perditions based on sensitivity studies and investigations that encompassed design factors such as well spacing, fracture properties and operational constraints

Incidence of Colorectal Cancer and Adenomatous Polyps After a Two-Step Screening in Isfahan Province, Iran in 2018

Purpose: The aim of this study was to estimate the incidence of colorectal cancers in Iran. The results of this study are based on a screening program that is being implemented in Isfahan province. Material and Methods: In this study, about 137,000 people were screened for colorectal cancer and adenomatous polyps in 2 steps during the year 2018. Results: Based on the findings of this study, the incidence of adenomatous polyps was reported to be 389 (95 CI, 365�422) per 100,000 population. The incidence of adenomatous polyps was reported to be 483 (95 CI, 446�520) and 316 (95 CI, 286�346) in men and women, respectively (p < 0.001). Also, the incidence of colorectal cancer was reported to be 33 (95 CI, 23�42) per 100,000 population. The incidence of colorectal cancer in men and women was reported to be 41 (95 CI, 30�51) and 26 (95 CI, 17�34), respectively, indicating a statistically non-significant difference (p = 0.29). Conclusion: Based on the result of this study, despite a low participation rate of the target population in the screening program, the incidence of adenomatous polyps and colorectal cancer is relatively high in the average-risk population. © 2019, Springer Science+Business Media, LLC, part of Springer Nature

Traffic accident mortality in Najafabad, Iran during 2011-2017

Background: Road traffic accident is one of the most important causes of disability and death in the young population. A significant number of people injured in road traffic accidents die after they arrive at the hospital. Objectives: This study aimed to assess the trend of mortality in road traffic accidents and forecast it for the coming years using time series modeling. Methods: This study investigated the trend of road traffic accidents and their victims in Najafabad, Iran, between 2011 and 2017. The ARIMA time series model was fitted on the obtained data and the best model was selected based on the least mean square error. Moreover, the model�s goodness of fit was investigated by residuals ACF and PACF plots as well as Ljung-Box chi-square statistics. Results: The trend analysis and ARIMA models were investigated, and the results showed a descending trend of fatalities due to traffic accident during 2011-2017. Afterwards, some models were fitted and ARIMA was selected (0, 1, 1), because it had the lowest mean square error value. By fitting the best model, the trend of traffic accident mortality was forecasted for five years (2018 to 2022). Finally, the forecasted values showed that future traffic accident mortalities had a decreasing trend. Conclusion: The trend of mortality due to road traffic injuries declined, indicating a decreasing trend in deaths for the upcoming years. Therefore, the interventions that have been applied in recent years may be considered as useful. © 2020 The Author(s)

Estimation of fracture height growth in layered tight/shale gas reservoirs using flowback gas rates and compositions–Part II: Field application in a liquid-rich tight reservoir

While hydraulic fracturing is the key to unlocking the potential of unconventional low-permeability hydrocarbon resources, challenges remain in the monitoring of subsurface propagation of fractures and the determination of which geologic intervals have been contacted. This is particularly challenging for wells that are completed in multiple hydraulic fracture stages (multi-fractured horizontal wells or MFHWs) where fracture spacing may be very close and fracture geometry complex. Understanding the fracture extent is important not only for assisting with hydraulic fracture design, but also for mitigating unwanted fracture growth into non-target geologic intervals that do not contain hydrocarbons (e.g. zones with high water saturation). Popular current technologies used for hydraulic fracture surveillance include microseismic (surface and subsurface monitoring) and tiltmeter surveys. While these methods have proven useful for characterizing the extent of created hydraulic fractures, they do not necessarily lead to an understanding of what portions of the geologic section (bounding and target intervals for MFHWs, for example) are in direct hydraulic communication with the well. A solution for establishing the extent of hydraulic fracture growth from target to bounding zones is to first obtain a fluid composition fingerprint of those intervals while drilling through them, and then compare these data with fluid compositions obtained from flowback after hydraulic fracturing. In the current work, a MFHW completed in a liquid-rich tight reservoir is used to test this novel concept. Gas samples extracted from the headspace of isojars® containing cuttings samples, obtained during drilling of the MFHW well, were used to geochemically fingerprint geologic intervals through which the well was drilled. The cuttings samples were collected at high frequency in the vertical, bend and lateral sections of the well over a measured depth range of 4725 ft (1440 m). A compositional marker was identified in the bend of the horizontal well above which the average methane to ethane (C1/C2) ratio was 15.7, versus 2.6 below it. The flowback gas compositions were observed to be intermediate (average C1/C2 = 7.4) between the reservoir above and below the marker, suggesting fracture height grew above the compositional marker. In order to estimate fracture height growth from the geologic interval and flowback compositions, a compositional numerical simulation study was performed. An innovative approach was used to estimate recombined in-situ fluid compositions, on a layer-by-layer basis, by combining the cuttings gas compositional data with separator oil compositions. The resulting numerical simulation model, initialized through use of the layered fluid model and a detailed geological model developed for the subject well and offset drilling locations, was used to history match flowback rates, pressures and gas compositions. The gas compositions of the fingerprinted geologic intervals were therefore employed as a constraint on fracture height growth, estimated in the model to be 175 ft (53 m, propped height). However, because of the uncertainty in model input parameters, a stochastic approach was required to derive a range in hydraulic fracture properties. The current study demonstrates for the first time that it is possible to constrain fracture height growth estimates from flowback data, combined with gas compositional data obtained from cuttings data, provided that the geochemical fingerprints are distinct