Photoelectric Factor Prediction Using Automated Learning and Uncertainty Quantification

The photoelectric factor (PEF) is an important well logging tool to distinguish between different types of reservoir rocks because PEF measurement is sensitive to elements with high atomic number. Furthermore, the ratio of rock minerals could be determined by combining PEF log with other well logs. However, PEF log could be missing in some cases such as in old well logs and wells drilled with barite-based mud. Therefore, developing models for estimating missing PEF log is essential in those circumstances. In this work, we developed various machine learning models to predict PEF values using the following well logs as inputs: bulk density (RHOB), neutron porosity (NPHI), gamma ray (GR), compressional and shear velocity. The predictions of PEF values using adaptive-network-fuzzy inference system (ANFIS) and artificial neural network (ANN) models have errors of about 16% and 14% average absolute percentage error (AAPE) in the testing dataset, respectively. Thus, a different approach was proposed that is based on the concept of automated machine learning. It works by automatically searching for the optimal model type and optimizes its hyperparameters for the dataset under investigation. This approach selected a Gaussian process regression (GPR) model for accurate estimation of PEF values. The developed GPR model decreases the AAPE of the predicted PEF values in the testing dataset to about 10% AAPE. This error could be further decreased to about 2% by modeling the potential noise in the measurements using the GPR model

Clay minerals damage quantification in sandstone rocks using core flooding and NMR

Sandstone oil reservoirs consist of different clay minerals such as kaolinite, illite, and chlorite. These clay minerals highly affect the formation damage during enhanced oil recovery (EOR) and well stimulation operations in these reservoirs. No attention was paid to investigate the effect of these clay minerals on the formation damage during different reservoir processes. In addition, no solution was introduced to mitigate the effect of clay minerals on the formation damage in sandstone reservoirs. In this study, the effect of clay mineral contents and type on the formation damage was studied in detail by injecting water and HCl as damaging fluids. Bandera grey, Berea, and Bandera brown sandstone rocks with various clay mineral contents were studied. XRD was used to characterize the sandstone rocks to determine the clay type and content in each rock. Two core plugs from each rock were selected for HCl and water injection. Core flooding experiments were performed to measure the initial and final permeability. In the core flooding experiments, fluids were injected into the cores at 25 °C and at a backpressure of 1000 psi. SEM was carried out before and after flooding for the tested rocks to locate the change in the clay distribution inside the rocks. The NMR analysis of core samples was done before and after flooding with the damaging fluid to quantify the formation damage and to find the possible damaging mechanism. NMR was used to locate the damage inside the rock due to the migration of clay minerals. Based on the core flooding, SEM, and NMR analysis, the maximum damage by the fresh water took place in Berea sandstone core due to fine migration and clay swelling. The illite clay mineral and chlorite can cause the formation damage on HCl injection. Illite can break down and migrates in the cores during the acid injection. In sandstone acidizing, chlorite clay mineral caused iron hydroxide precipitation inside the cores during treatment with mud acid. NMR showed that clay minerals plugged the pore throats of the rocks and reduced the rock permeability during the injection of fresh water

Traumatic Dural Venous Sinuses Injury

The traumatic dural venous sinus injury is one of the most dangerous complications of TBI, either due to fatal intracranial compressing venous bleeding, or disturbing the intracranial pressure which could be caused by injury to the SSS On the other hand, post traumatic dural sinus thrombosis is considered a rare complication which may lead to hemorrhagic infarction with its serious consequences including epilepsy, neurological deficits, or death. Therefore, knowledge of the appropriate treatment of this kind of head injury is essential

Comparison between Results of Microdiscectomy and Open Discectomy in Management of High-Level Lumbar Disc Prolapse

AIM: This work aims to compare between results of microdiscectomy and open discectomy in management of high-level lumbar disc prolapse. METHODS: This is a controlled randomised study, where patients having upper lumbar disc herniations were evaluated preoperatively both clinically and radiologically, randomisation was planned to perform open discectomy in odd number patients and to perform microdiscectomy in even number patients, patients were evaluated and followed up for deficits and outcomes. RESULTS: We operated ten patients in this study, five cases were operated upon with microdiscectomy, and five cases were operated upon with open discectomy, the median age of presentation in this study was 44 years, there were five males and five females, postoperative pain improvement was better in microdiscectomy. Hospital stay, blood loss, bone loss and postoperative complications were less in microdiscectomy. CONCLUSION: Microdiscectomy allows good surgical visualisation and is less traumatic to the involved tissues. The results of this study indicated that microsurgery reduces hospitalisation time, improves the overall surgery-related outcome. The main differences between the two procedures were the length of the incision and blood loss. We found that lumbar microdiscectomy allows patients earlier return to work and normal life with less reliance on postoperative narcotic analgesic agents

Hypoglossal Facial Nerve Anastomosis for Post-Operative and Post-Traumatic Complete Facial Nerve Paralysis

AIM: This study aims to evaluate the outcome of patients with complete facial paralysis following surgery to cerebellopontine angle tumours or following traumatic petrous bone fractures after reanimation by hypoglossal-facial anastomosis as regards clinical improvement of facial asymmetry and facial muscle contractility as well as complications associated with hypoglossal-facial reanimation procedure. METHODS: This thesis included a prospective study to be carried out on 15 patients with unilateral complete lower motor neuron facial paralysis (11 patients after cerebellopontine angle tumour resection and 4 patients after traumatic transverse petrous bone fracture) operated upon by end to end hypoglossal-facial nerve anastomosis in Cairo university hospitals in the period between June 2015 and January 2017. RESULTS: At one year follow up the improvement of facial nerve functions were as follows: Three cases (20%) had improved to House Hrackmann grade II, eleven cases (73.33%) had improved to grade III, and one patient (6.66%) had improved to House Brackmann grade IV. CONCLUSION: Despite the various techniques in facial reanimation following facial nerve paralysis, the end to end hypoglossal-facial nerve anastomosis remains the gold standard procedure with satisfying results in cases of the viable distal facial stump and non-atrophic muscles. Early hypoglossal-facial anastomotic repair after acute facial nerve injury is associated with better long-term facial function outcomes and should be considered in the management algorithm

Functional Outcomes of Surgical Management for Spinal Epidural Masses in an Egyptian Tertiary Hospital

BACKGROUND: The spinal epidural space, covering the dural sac, is located along the posterior longitudinal ligament anteriorly, the ligamentum flavum and the periosteum of laminae posteriorly, and the pedicles of the spinal column by the intervertebral foramina containing their neural elements laterally. It could be affected variably by different types of diseases, either as primary lesions or as an extension from a disease process in the nearby tissues and organs. AIM: We aimed to present clinically and surgically patients with spinal epidural masses operated in the Neurosurgery Department of Cairo University Hospitals, Cairo, Egypt, along a time interval of one year. METHODS: In this prospective cohort study, we analysed motor deficits, sensory deficits, and bowel and bladder dysfunction. We have performed decompressive laminectomy on 19 patients with spinal epidural masses together with mass excision as long as the tumour was accessible, with or without fixation. RESULTS: All patients were radiologically assessed by MRI over the affected side of the spine. D10 was the commonest site in our study to be affected in 10 cases of our participants (23%), followed by D5, D7, and D12 each of them was affected in 6 cases (14%), in another word spinal segments by order of frequency to be affected were dorsal followed by lumbar spine. All patients included in this study (100%) showed an obvious improvement as regard pain and tenderness. CONCLUSION: Surgical interventions have improved the quality of life for our patients with spinal epidural masses

Cranioplasty: A New Perspective

AIM: This work aims to present the different indication, benefits, possible complications and methods used for fixation of methyl methacrylate in cranioplasty. Also, 50 cases will be presented demonstrating the different aetiologies of the defects, and the different techniques used for fixation of methyl methacrylate in cranioplasty. METHODS: This investigation included a prospective study to be carried out on 50 patients with cranial defects of different aetiologies, sites and sizes to be operated upon in Cairo University Hospitals starting from August 2016 to April 2017.RESULTS: The principal aims of cranioplasty in this study are to restore aesthetic contour and to provide cerebral protection. However, it has been noted that a great improvement occurs in cerebral blood flow and cerebral perfusion after cranioplasty. CONCLUSION: Ball and socket technique appear to be a simple, safe economic and efficient method for fixation of cranioplasty flap. The high incidence of development of postoperative seroma suggests the necessity of-of a subgaleal drain placement for 48 hours. &nbsp

Comparison of the Effects of Albumin 5% versus Ringer's Lactate on Blood Loss and Coagulation after Vascular Surgery Using Thromboelastography

AIM: Comparing the effects of Albumin 5% versus Ringer's lactate on blood loss and coagulation after vascular surgery using METHODS: In this randomised study, 60 patients, aged (18-60 years) ASA physical status (I-III) undergoing vascular surgery were included in the study and randomly allocated into two groups using a random number generator, to receive either Human albumin or Ringer lactate after obtaining written informed consent. Group A received 1-2 ml per minute of human albumin 5% combined with normal saline (0.9%). Group B received Ringer's lactate only as of the main solution. Variables were measured after administration of fluids as postoperative measures. The amount of blood needed for testing was 4 ml drawn before the operation and at the end of surgery with a citrate tube (blue tube) from the venous line or using a regular needle. The standard time of 15 minutes was considered to begin processing. RESULTS: There was no statistically significant difference observed between both groups regarding demographic data, surgical wound drainage, haemoglobin level, hematocrit level and coagulation profile. Regarding ROTEM thermoelectrometry variables showed that there was no statistically significant difference was found between the two groups In-TEM variables (Ex-TEM Clotting time, TEM Clot Formation Time) but In-TEM Alpha Angel measured in degrees showed a Statistically significant difference between the two groups. P < 0.001 and Ex-TEM Maximum Clotting Firmness MCF values measured in mm, there was a statistically significant difference between the two groups P = 0.045. CONCLUSION: This study concluded that the use of human albumin (5%) in vascular surgeries before reaching the trigger point for blood transfusion didn’t improve blood loss or coagulation profile compared to the use of ringer lactate only. Therefore, ringer lactate can be used as a good replacement for human albumin. Ringer lactate is readily available and inexpensive while human albumin may be costly

Development of a Homogenous Cement Slurry Using Synthetic Modified Phyllosilicate while Cementing HPHT Wells

Cement slurry segregation has a detrimental impact on the cement matrix efficiency in term of zonal isolation. In this study, synthetic modified phyllosilicate (SMP) dispersant, which is known as laponite RD is suggested to reduce the slurry segregation and enhance the vertical homogeneity of the cement matrix in term of density distribution. Seven cement slurries were prepared with different SMP concentrations using molds with different dimensions based on the targeted test, then cured for 24 h at 140 °C and 3000 psi using a high-pressure and high-temperature curing chamber. After that, the samples’ density distribution was evaluated using a direct density measurement and computer tomography (CT) scan imaging technique, and the effect of SMP on the cement rheological parameters, permeability, and compressive strength and were also evaluated. The performance of SMP was then compared with a commercial dispersant. As a result, 0.3% by weight of cement (BWOC) of SMP is found to considerably reduce the vertical density variation along the cement column to 0.46% compared with a density variation of 4.78% for the slurry with the commercial dispersant. The CT scan images confirmed the vertical homogeneity of the slurry with 0.3% BWOC of SMP. Addition of 0.3% BWOC of SMP increased the yield point of the cement slurry to 60.6 MPa compared with 20.5 MPa for the slurry with 0.25% of the commercial dispersant. Adding 0.3% BWOC of SMP into the cement formulation decreased the permeability by 37.1% compared with the commercial dispersant. The sample with 0.3% BWOC of SMP has a compressive strength of 43.9 MPa