Determination of the Rate of Penetration by Robust Machine Learning Algorithms Based on Drilling Parameters

Underground resources, particularly hydrocarbons, are critical assets that promote economic development on a global scale. Drilling activities are necessary for the extraction and recovery of subsurface energy resources, and the rate of penetration (ROP) is one of the most important drilling parameters. This study forecasts the ROP using drilling data from three Iranian wells and hybrid LSSVM-GA/PSO algorithms. These algorithms were chosen due to their ability to reduce noise and increase accuracy despite the high level of noise present in the data. The study results revealed that the LSSVM-PSO method has an accuracy of roughly 97% and is more precise than the LSSVM-GA technique. The LSSVM-PSO algorithm also demonstrated improved accuracy in test data, with RMSE = 1.92 and R2 = 0.9516. Furthermore, it was observed that the accuracy of the LSSVM-PSO model improves and degrades after the 50th iteration, whereas the accuracy of the LSSVM-GA algorithm remains constant after the 10th iteration. Notably, these algorithms are advantageous in decreasing data noise for drilling data.

A novel directional-oriented method for predicting shear wave velocity through empirical rock physics relationship using geostatistics analysis

This study attempts to design a novel direction-oriented approach for estimating shear wave velocity (VS) through geostatistical methods (GM) using density employing geophysical log data. The research area involves three hydrocarbon wells drilled in carbonate reservoirs that are comprised of oil and water. Firstly, VS was estimated using the four selected empirical rock physics relationships (ERR) in well A (target well), and then all results were evaluated by ten statistical benchmarks. All results show that the best ERR is Greenberg and Castagna, with R2 = 0.8104 and Correlation = 0.90, while Gardner's equation obtained the poorest results with R2 = 0.6766 and correlation = 0.82. Next, Gardner's method was improved through GM by employing Ordinary Kriging (OKr) in two directions in well A, and then Cross-Validation and Jack-knife methods (JKm and CVm, respectively) were used to assess OKr's performance and efficiency. Initially, CVm and JKm were employed to estimate Vs using the available density and its relationship with shear wave velocity, where the performance of CVm was better with R2 = 0.8865 and correlation = 0.94. In this step, some points from the original VS were used to train the data. Finally, Vs was estimated through JKm and using the relationship between the shear wave velocity of two wells near the target well, including wells B and C; however, in this step, the original shear wave velocity of the target well was completely ignored. Reading the results, JKm could show excellent performance with R2 = 0.8503 and Corr = 0.922. In contrast to previous studies that used only Correlation and R-squared (R2), this study further provides accurate results by employing a wide range of statistical benchmarks to investigate all results. In contrast to traditional empirical rock physics relationships, the developed direction-oriented technique demonstrated improved predicted accuracy and robustness in the investigated carbonate field. This work demonstrates that GM can effectively estimate Vs and has a significant potential to enhance VS estimation using density.

Numerical simulation and diagnosis geotechnical parameters of historical buildings in Najran City, Kingdom of Saudi Arabia

This research aims to assess geoenvironmental risks and identify the primary deterioration drivers in ancient buildings in Najran City, utilizing various analytical tools to help make informed judgments. The samples extruded from historical buildings were examined using field inspection, experimental data, SEM, EDX, and XRD analyses, in addition to lab and field observations and meteorological data. The dissolution of clay minerals and salt crystallization are the key contributors to the degradation and cracking of historical buildings in Najran City, according to lab and field observations. When the daytime high temperature surpasses 44 °C, wind erosion and humidity might cause continuous wetting-drying cycles on the investigated building surfaces. Test results indicated that the average unconfined compressive strength of the extruded earthen wall samples was 2 MPa and the water absorption was within the upper allowed limit (i.e., 15%). A finite element model of a typical earthen historical building was developed using PLAXIS 3D software to assess the behavior and nonlinear response of the silty sand soil layer underlying the building and the earthen historical buildings themselves using a plastic material model. The field observations confirm the results of the simulation, which clearly explained the failure mechanism. The integrated geotechnical and numerical simulations could provide insights for assessing geoenvironmental risks, identify the primary deterioration drivers in ancient buildings, and provide an understanding of material qualities and failure causes not only in the studied area but in other similar regions elsewhere.

Experimental study of the influence of the degree of saturation on physical and mechanical properties of carbonate rocks in the Jurassic Tuwaiq Mountain Formation (Saudi Arabia)

Understanding the impact of saturation levels on the mechanical and physical properties of limestone and marly limestone deposits is very critical for geotechnical and mechanical studies in the energy and construction industries. This research aims to link the strength characteristics of carbonate rock (limestone and marly limestone) with physical and mechanical properties at saturation levels of 0, 0.25, 50%, 75% and 100%. To complete this work, 100 samples were collected and analysed employing an orderly research facility testing. According to experimental findings, the strength and durability of the limestone and marly limestone declined with rising saturation levels, while the P‐wave velocity Vp showed an upward trend from 0% to 100%. The uniaxial compressive strength (UCS) of the limestones employed in this research significantly decreased (up to 36%) between the dry and saturated stages for limestone samples. While marly limestone, there is a drop (up to 32%) in UCS. The findings of a straightforward regression study show that it is possible to predict the strength properties of rocks directly from various saturation levels. Additionally, a number of various estimate connections were created utilizing independent variables like Vp and saturation level. The experimental outcomes showed that Vp showed an upward tendency with an increasing degree of saturation. The deformability and strength parameters of the samples declined with increasing saturation degrees. The elastic modulus and strength both decrease as clay and water amounts increase. The quality index (QI) number for limestone is 45, which indicates that it has extremely good quality and can be used as a building material at 0% saturation. At 25%, 50%, 75% and 100% saturation, it is evaluated at 43, 40, 33 and 31, respectively. The marly limestone samples have high quality at 0% (QI = 36), but poor quality at 25%, 50%, 75% and 100% saturation (QI = 33, 30, 27 and 23). This research provides a better understanding of the relationship between saturation levels and the mechanical, physical and depositional characteristics of marly limestone and limestone, which might be helpful in industrial studies. Advance examination of distinctive sorts of carbonate rocks can be more supportive of broadening our understanding of this idea.

In Situ Stress Determination Based on Acoustic Image Logs and Borehole Measurements in the In-Adaoui and Bourarhat Hydrocarbon Fields, Eastern Algeria

The study of in situ stress from image logs is a key factor for understanding regional stresses and the exploitation of hydrocarbon resources. This work presents a comprehensive geomechanical analysis of two eastern Algerian hydrocarbon fields to infer the magnitudes of principal stress components and stress field orientation. Acoustic image logs and borehole measurements were used in this research to aid our understanding of regional stress and field development. The studied In-Adaoui and Bourarhat fields encompass a combined thickness of 3050 m of Paleozoic and Mesozoic stratigraphy, with the primary reservoir facies in the Ordovician interval. The Ordovician sandstone reservoir interval indicates an average Poisson’s ratio (v) of 0.3, 100–150 MPa UCS, and 27–52 GPa Young’s modulus (E). Direct formation pressure measurements indicate that the sandstone reservoir is in a hydrostatic pore pressure regime. Density-derived vertical stress had a 1.1 PSI/feet gradient. Minimum horizontal stress modeled from both Poisson’s ratio and an effective stress ratio-based approach yielded an average 0.82 PSI/feet gradient, as validated with the leak-off test data. Drilling-induced tensile fractures (DITF) and compressive failures, i.e., breakouts (BO), were identified from acoustic image logs. On the basis of the DITF criterion, the maximum horizontal stress gradient was found to be 1.57–1.71 PSI/feet, while the BO width-derived gradient was 1.27–1.37 PSI/feet. Relative stress magnitudes indicate a strike-slip stress regime. A mean SHMax orientation of N130°E (NW-SE) was interpreted from the wellbore failures, classified as B-quality stress indicators following the World Stress Map (WSM) ranking scheme. The inferred stress magnitude and orientation were in agreement with the regional trend of the western Mediterranean region and provide a basis for field development and hydraulic fracturing in the low-permeable reservoir. On the basis of the geomechanical assessments, drilling and reservoir development strategies are discussed, and optimization opportunities are identified.

Evaluation insight into Abu Zenima clay deposits as a prospective raw material source for ceramics industry: Remote Sensing and Characterization

The rapid development and mutations have heightened ceramic industrialization to supply the countries' requirements worldwide. Therefore, the continuous exploration for new reserves of possible ceramic-raw materials is needed to overwhelm the increased demand for ceramic industries. In this study, the suitability assessment of potential applications for Upper Cretaceous (Santonian) clay deposits at Abu Zenima area, as raw materials in ceramic industries, was extensively performed. Remote sensing data were employed to map the Kaolinite-bearing formation as well as determine the additional occurrences of clay reserves in the studied area. In this context, ten representative clayey materials from the Matulla Formation were sampled and examined for their mineralogical, geochemical, morphological, physical, thermal, and plasticity characteristics. The mineralogical and chemical compositions of starting clay materials were examined. The physicochemical surface properties of the studied clay were studied utilizing SEM-EDX and TEM. The particle-size analysis confirmed the adequate characteristics of samples for white ceramic stoneware and ceramic tiles manufacturing. The technological and suitability properties of investigated clay deposits proved the industrial appropriateness of Abu Zenima clay as a potential ceramic raw material for various ceramic products. The existence of high kaolin reserves in the studied area with reasonable quality and quantity has regional significance. It would significantly help reduce the manufacturing cost and overwhelm the high consumption rate. The ceramic manufacturers in the investigated areas are expected to bring steady producers into the industry in the long term to gain the advantage of low-cost raw materials, labor, and factory construction.

Reservoir Formation Damage; Reasons and Mitigation: A Case Study of the Cambrian–Ordovician Nubian ‘C’ Sandstone Gas and Oil Reservoir from the Gulf of Suez Rift Basin

Reservoir formation damage is a major problem that the oil and gas industry has to mitigate in order to maintain the oil and gas supply. A case study is presented that identifies the impacts of formation damage and their causes in the Nubian ‘C’ hydrocarbon reservoir within Sidki field located in the Southern Gulf of Suez, Egypt. In addition, a formation damage mitigation program was designed and implemented involving an effective stimulation treatment for each well experiencing reservoir damage. The data available for this study include core analysis to provide rock mineralogy and lithology; analysis of production fluid data; water chemistry; drilling fluid composition; perforations and well completion details; workover operations; and stimulation history. The diagnosis of formation damage based on the integrated assessment of the available data is associated with several benefits, (1) The integration of the data available helps provide a robust analysis of formation damage causes and in establishing suitable remediation actions, (2) Workover fluid is confirmed as the primary cause of reservoir damage in the studied well, (3) Several reservoir damage mechanisms were identified including water blockage, solids and filtrate invasion, fluid/rock interaction (deflocculation of kaolinite clay), salinity shock and/or high-sulfate content of the invaded fluid, (4) Irrespective of the potential causes of formation damage, the primary objective of a gas production company is to mitigate its effects and the integrated dataset helps to design appropriate and effective stimulation treatments to overcome formation damage, and (5) In gas reservoirs, especially low permeability ones, extra precautions are necessary to avoid potential reservoir damage due to workover fluid invasion.

Nanopillared Chitosan/Gelatin Films: A Biomimetic Approach for Improved Osteogenesis

Biomimicry strategies, inspired from natural organization of living organisms, are being widely used in the design of nanobiomaterials. Particularly, nonlithographic techniques have shown immense potential in the facile fabrication of nanostructured surfaces at large-scale production. Orthopedic biomaterials or coatings possessing extracellular matrix-like nanoscale features induce desirable interactions between the bone tissue and implant surface, also known as osseointegration. In this study, nanopillared chitosan/gelatin (C/G) films were fabricated using nanoporous anodic alumina molds, and their antibacterial properties as well as osteogenesis potential were analyzed by comparing to the flat C/G films and tissue culture polystyrene as controls. In vitro analysis of the expression of RUNX2, osteopontion, and osteocalcin genes for mesenchymal stem cells as well as osteoblast-like Saos-2 cells was found to be increased for the cells grown on nano C/G films, indicating early-stage osteogenic differentiation. Moreover, the mineralization tests (quantitative calcium analysis and alizarin red staining) showed that nanotopography significantly enhanced the mineralization capacity of both cell lines. This work may provide a new perspective of biomimetic surface topography fabrication for orthopedic implant coatings with superior osteogenic differentiation capacity and fast bone regeneration potential.

Long-acting intraocular Delivery strategies for biological therapy of age-related macular degeneration

As one of the leading causes of central vision loss in elderly population, worldwide cases of age-related macular degeneration (AMD) have seen a dramatic increase over the past several years. Treatment regimens for AMD, especially with biological agents, are complicated due to anatomical and physiological barriers, as well as administration of high doses and frequent regimens. Some clinical examples include monthly intravitreal administration of anti-VEGF antibody ranibizumab (Lucentis®) from Genentech and aflibercept (Eylea®) from Regeneron Pharmaceuticals. Long-acting sustained intraocular drug delivery provides promising solutions, such as Vitrasert® from Bausch & Lomb, an intravitreal biodegradable polymeric implant made from poly(D,L-lactic co glycolic acid) (PLGA), and can be used as a guiding reference to formulate sustained delivery systems. In this review, we discuss the anatomy and physiology of the eye, barriers to delivery, pathology of AMD, opportunities for biological therapeutics, and future prospects of intraocular delivery strategies that are in development for treatment of AMD.

Medical undergraduates' contributions to publication output of world's top universities in 2013

BACKGROUND

Medical undergraduates' (UGs) involvement in research activities is thought to be mutually beneficial to students, their mentors and the scholarly productivity of their universities. However, most evidence in favor of such assumption relies on subjective measures such as the self-reported gains in skills or knowledge rather than robust objective estimates for assessing impact.

AIM

We aimed to objectively track and describe publications with UG co-authors-their proportion to the total publication output of world's top universities, their characteristics and their potential impact on biomedical literature.

METHODS

We contacted the corresponding authors of the 2013's Medline-indexed publications affiliated to world's top 10 universities to investigate if any of their co-authors was an UG. Articles with UG co-authors were further assessed to determine, along with other variables: the type of study design, field of the article, publishing journal and its impact factor (IF), and number of received citations.

RESULTS

Out of 25 152 publications, 2537 articles (10.1%) contained at least one UG co-author who was the first author in 635 papers (25%). Articles with UG co-authors were published in 1114 journals with a median IF of 3.661. Most UGs' co-authored publications (82.7%, n = 2098) were cited at least once within 1 year, for a median of three citations per article.

CONCLUSION

UGs contributed to one in every 10 publications affiliated to top universities. Their papers were published in journals with good IFs and received a fair number of citations, which would reflect the relatively good quality and impact of these articles.

Perspective of ophthalmology residents in the United States about residency programs and competency in relation to the International Council of Ophthalmology guidelines

Purpose

To evaluate the perspective of ophthalmology residents in the US about their residency programs and compare the competency of residency programs to international competency levels set by the International Council of Ophthalmology (ICO).

Methods

A cross-sectional web-based survey extracted from the ICO published competency standards was sent to program directors of ophthalmology residency programs in the US to forward it to current PGY-3, 4 residents, and residency graduates from 2011 to 2014.

Results

Eighty-seven responses were received, comprising 61 residents and 26 graduates. Most respondents were highly satisfied with their programs (93.6%). Clinic-based training was rated satisfactorily. Insufficient exposure to low-vision rehabilitation (38.5%), refraction and contact lenses prescription (38.5%), and vitreo-retinal surgeries (38.5%) was reported. Respondents were satisfied with their overall surgical experiences, with the vast majority (>83%) rating case volume, complexity, and variety as satisfactory or better. A significant group stated they had insufficient exposure to extra-capsular cataract extraction (26.3%), refractive surgery (19.7%), and orbital surgery (64.5%). All graduates surveyed passed their Ophthalmic Knowledge Assessment Program (OKAP) examinations, and 72% felt their residency programs adequately prepared them for the examinations. All respondents reported insufficient training in certain nonclinical areas, such as practice management, staffing, and administration skills.

Conclusions

Ophthalmology residents in the US express high levels of satisfaction with their residency training programs. While most programs adequately address most ICO core objectives, certain curriculum modifications should be considered.

Perception and use of massive open online courses among medical students in a developing country: multicentre cross-sectional study

OBJECTIVES

To assess the prevalence of awareness and use of massive open online courses (MOOCs) among medical undergraduates in Egypt as a developing country, as well as identifying the limitations and satisfaction of using these courses.

DESIGN

A multicentre, cross-sectional study using a web-based, pilot-tested and self-administered questionnaire.

SETTINGS

Ten out of 19 randomly selected medical schools in Egypt.

PARTICIPANTS

2700 undergraduate medical students were randomly selected, with an equal allocation of participants in each university and each study year.

PRIMARY AND SECONDARY OUTCOME MEASURES

Primary outcome measures were the percentages of students who knew about MOOCs, students who enrolled and students who obtained a certificate. Secondary outcome measures included the limitations and satisfaction of using MOOCs through five-point Likert scale questions.

RESULTS

Of 2527 eligible students, 2106 completed the questionnaire (response rate 83.3%). Of these students, 456 (21.7%) knew the term MOOCs or websites providing these courses. Out of the latter, 136 (29.8%) students had enrolled in at least one course, but only 25 (18.4%) had completed courses earning certificates. Clinical year students showed significantly higher rates of knowledge (p=0.009) and enrolment (p<0.001) than academic year students. The primary reasons for the failure of completion of courses included lack of time (105; 77.2%) and slow Internet speed (73; 53.7%). Regarding the 25 students who completed courses, 21 (84%) were satisfied with the overall experience. However, there was less satisfaction regarding student-instructor (8; 32%) and student-student (5; 20%) interactions.

CONCLUSIONS

About one-fifth of Egyptian medical undergraduates have heard about MOOCs with only about 6.5% actively enrolled in courses. Students who actively participated showed a positive attitude towards the experience, but better time-management skills and faster Internet connection speeds are required. Further studies are needed to survey the enrolled students for a better understanding of their experience.

Development of an Arabic version of the National Eye Institute Visual Function Questionnaire as a tool to study eye diseases patients in Egypt

AIM

To develop and test an Arabic version of the National Eye Institute Visual Function Questionnaire-25 (NEI-VFQ-25).

METHODS

NEI-VFQ-25 was translated into Arabic according to WHO translation guidelines. We enrolled adult consenting patients with bilateral chronic eye diseases who presented to 14 hospitals across Egypt from October to December 2012, and documented their clinical findings. Psychometric properties were then tested using STATA.

RESULTS

We recruited 379 patients, whose mean age was (54.5±15)y. Of 46.2% were males, 227 had cataract, 31 had glaucoma, 23 had retinal detachment, 37 had diabetic retinopathy, and 61 had miscellaneous visual defects. Non-response rate and the floor and ceiling numbers of the Arabic version (ARB-VFQ-25) were calculated. Internal consistency was high in all subscales (except general health), with Cronbach-α ranging from 0.702-0.911. Test-retest reliability was high (intraclass correlation coefficient 0.79).

CONCLUSION

ARB-VFQ-25 is a reliable and valid tool for assessing visual functions of Arabic speaking patients. However, some questions had high non-response rates and should be substituted by available alternatives. Our results support the importance of including self-reported visual functions as part of routine ophthalmologic examination.

Modeling traffic accident occurrence and involvement

The Negative Binomial modeling technique was used to model the frequency of accident occurrence and involvement. Accident data over a period of 3 years, accounting for 1,606 accidents on a principal arterial in Central Florida, were used to estimate the model. The model illustrated the significance of the Annual Average Daily Traffic (AADT), degree of horizontal curvature, lane, shoulder and median widths, urban/rural, and the section's length, on the frequency of accident occurrence. Several Negative Binomial models of the frequency of accident involvement were also developed to account for the demographic characteristics of the driver (age and gender). The results showed that heavy traffic volume, speeding, narrow lane width, larger number of lanes, urban roadway sections, narrow shoulder width and reduced median width increase the likelihood for accident involvement. Subsequent elasticity computations identified the relative importance of the variables included in the models. Female drivers experience more accidents than male drivers in heavy traffic volume, reduced median width, narrow lane width, and larger number of lanes. Male drivers have greater tendency to be involved in traffic accidents while speeding. The models also indicated that young and older drivers experience more accidents than middle aged drivers in heavy traffic volume, and reduced shoulder and median widths. Younger drivers have a greater tendency of being involved in accidents on roadway curves and while speeding.