Among all the methods used for determining FLUID SATURATION of the reservoir rock, the ability of neural networks to predict FLUID SATURATION in reservoir rock is of great interest to researchers. This study gathers the necessary data for estimating this important reservoir parameter and the variables involved in the process. Afterward, artificial neural networks (ANNs) and particle swarm optimization (PSO) algorithms are combined to provide a proper and accurate model for estimating water SATURATION. This combination provides an outstanding model in which FLUID SATURATION distribution at any point in one of Iran’s carbonate oil reservoirs can be obtained. To predict the water SATURATION value as the model output, several input parameters, including depth, gamma ray, resistance, neutron, micro-spherical resistance, and spontaneous potential logs, are employed. The multi-layer perceptron neural network (MLP) and radial basis function neural network (RBF) are the two models used, and the accuracy of each model is examined. Although the relationship between FLUID SATURATION in the reservoir and logging information is completely nonlinear, these two artificial intelligence (AI) models can very well recognize this nonlinear relationship and provide great predictions with high correlation coefficient (R) values and low average absolute relative deviation (AARD) and root mean square error (RMSE) values. The values of R, AARD, and RMSE for the MLP model are obtained as 0.9739, 33.24, and 0.0824, respectively. Those for the RBF model are 0.9986, 7.47, and 0.0024, respectively, reflecting that the RBF model is superior to the MLP model due to its higher R value and lower AARD and RMSE values.

Due to majority of relative permeability in reservoir engineering studies and its dependency to some physical properties, relative permeability measurement is the most complicated task in special core analysis studies. Equilibrium in front flow during flooding and recognizing the end effect capillary pressure in relative permeability tests is very important. For this reason the usage of in-situ SATURATION measurement methods has a paramount importance. Also performing SCAL tests in reservoir conditions and using reservoir oil creates correct and real data for reservoir engineers to apply in reservoir models. In this study, the goal of which is the determination of in-situ SATURATION during flooding in reservoir conditions, first four plug samples from Asmari formation were selected and thin section studies were done to recognize the lithologies and important features. Then using relative permeability apparatus in ambient condition, the average SATURATIONs of FLUIDs in the cores were determined by measuring the volume of FLUIDs expelled from the samples in the flooding test and the relative permeability curves were plotted. In the next step using x-ray relative permeability apparatus, the relative permeability experiments in the reservoir conditions were performed and the value of in-situ FLUID SATURATION and the average SATURATION were determined via measuring the intensity of x-ray passes through the core. The results obtained from relative permeability tests in ambient and reservoir condition were then compared. Dead crude oil from Asmari formation has been used in all experiments.

Displacement of oil and water in porous media of reservoir rocks is described by relative permeability curves, which are important input data for reservoir performance simulation and drive mechanism studies. Many core studies, such as multiphase relative permeability, capillary pressure and SATURATION exponent determination, depend on the volume fractions of multiphase FLUIDs present in the studied rock samples. X-ray scanners are increasingly used for measurement of FLUIDs SATURATION in the core samples during core studies, mainly due to expanding need of modeling and measuring reservoir condition FLUID flow behavior and its being safer issues than other radioactive sources like gamma ray. Incorporating X-Ray in situ SATURATION measurements into the relative permeability, capillary pressure and intrinsic wettability characterization of reservoir rocks may improve reservoir management and productivity prediction. This paper describes two phase immiscible FLUID flow behavior of oil displaced by water through water wet porous media interpreted by X-ray data utility, according to SATURATION profile shapes incorporated by history matching of oil production and differential pressure history in low oil to water viscosity ratio FLUID flow. In situ SATURATION profiles have been obtained with 1% SATURATION accuracy. The in situ SATURATION profiles confirm wettability character of reservoir rock samples and are an indication of the fact that initial water SATURATION and non-wetting oil phase values are controlled by reservoir rock wettability characteristics. The immovable water SATURATION increases because of oil snap-off and when light oil enters a water wet porous media, even increasing the oil injection rate cannot overcome van der Waals forces throughout water molecules. The SATURATION profiles have been shaped rather flat after water breakthrough. These profiles attribute to the recovery of the bulk of oil before breakthrough in low viscosity ratio displacement through water wet rocks. Besides, overlapping of various after bump SATURATION profiles indicates that there is no significant difference between remaining oil SATURATION and residual oil SATURATION in water wet reservoir rocks.

The determination of FLUID SATURATION is vital for the estimation of hydrocarbon in place which is the base for economic decision making about reservoir production. Archie’s equations are the most prevalent equations used for SATURATION calculation. One of the important parameters in these equations is SATURATION exponent.SATURATION exponent has fundamental difference comparing with other parameters which are cementation exponent and tortuosity. Cementation exponent and tortuosity mostly depend on rock type but SATURATION exponent depends on the distribution of FLUIDs and therefore the hysteresis of SATURATION during imbibitions and drainage and also wettability. The purpose of this research is an investigation into the effect of SATURATION hysteresis and wettability on SATURATION exponent. The SATURATION exponent was measured from primary drainage to secondary drainage with a four-electrode system at reservoir temperature with reservoir FLUIDs on some cylindrical core samples. Dynamic porous plate technique was used, for which full capillary pressure curves and wettability with combined Amott-USBM were determined simultaneously. It was concluded that the SATURATION hysteresis affects SATURATION exponent in different samples during imbibition and drainage and cause it to range from 0.1 to 0.66; the variations were higher in oil-wet samples than water-wet samples.

The time lapse gravity method is a widely used technique to monitor the subsurface density changes in time and space. In hydrocarbon reservoirs, the density variations are due to different factors, such as: substitution of FLUIDs with high density contrast, water influx, gas injection, and the variation in reservoir geomechanical behavior. Considering the monitoring of SATURATION changes in the reservoir that cannot be inferred directly by seismic survey, a forward modelling followed by a sensitivity study is performed to examine that in what conditions the SATURATION changes are detectable by means of 4D gravity method in the understudy reservoir. Then static and dynamic models of a giant multi-phase gas reservoir are constructed. Then, synthetic gravity data are generated after variation of production time intervals and the number of production and injection wells. In addition to detecting the gravity signal for shallower reservoirs with similar characteristics to our reservoir, a sensitivity analysis was conducted for variation in depth of the reservoir. As either the depth of the reservoir decreases or the number of the production wells and production time periods increases, the produced gravity signal is more prone to be detectable by means of modern offshore gravimeters. The gravity signal could be detected with the maximum magnitude range of 9-40 μ Gal in different scenarios as a consequence of gas-water substitution, which is consistent with water drive support from surrounding aquifers. Therefore, this method is applicable for providing complementary and even independent source of information about the SATURATION front changes in the under-study reservoir.

Introduction: Use of an adhesive with a suitable composite resin is an important factor in tooth-colored restorations and increasing marginal sealing ability. The aim of this study was to evaluate the microleakage of various adhesives with composite resins using FLUID filtration and dye extraction techniques and assessment of the correlation between these two techniques.Materials and Methods: In this in vitro study, class II cavities were prepared on the proximal surfaces of 48 extracted sound human premolar teeth, measuring 1.5±0.5 mm in gingival width, 4 mm in occluso-gingival height and 1.3 of the inter-cuspal distance in width. The samples were divided into four groups (n=12). Group 1; OptiBond Solo Plus adhesive/Herculite XRV composite resin; Group 2: OptiBond Solo Plus adhesive/Master Dent composite resin; Group 3: Prime & Bond NT adhesive/Herculite XRV composite resin; Group 4: Prime & Bond NT adhesive/Master Dent composite resin. Microleakage was assessed primarily by FLUID filtration and then by dye extraction techniques. Data were analyzed with Kruskal-Wallis and Mann-Whitney tests, with Bonferroni correction and Spearman's rho correlation test at 95% confidence interval.Results: The minimum and maximum mean microleakage values were recorded in FLUID filtration and dye extraction techniques groups 1 and 4, respectively. There were significant differences between the experimental groups in microleakage with the two methods of leakage assessment (p value=0.001). Spearman's rho revealed a strongly direct correlation between the two methods (r=0.797, p value=0.000).Conclusion: In both methods of microleakage assessment, use of ethanol-based in comparison to acetone-based adhesive resulted in microleakage reduction. Application of light-cured composite resin contrary to self-cured composite resin with both types of adhesives increased marginal sealing ability.

Background: Liver transplant is the only definitive treatment for many patients with end stage liver disease. Presence and severity of preoperative pulmonary disease directly affect the rate of postoperative complications of the liver transplantation. Arterial blood gas (ABG) measurement, performed in many transplant centers, is considered as a traditional method to diagnose hypoxemia. Because ABG measurement is invasive and painful, pulse oximetry, a bedside, noninvasive and inexpensive technique, has been recommended as an alternative source for the ABG measurement.Objectives: The aim of this study was to evaluate the efficacy of pulse oximetry as a screening tool in hypoxemia detection in liver transplant candidates and to compare the results with ABGs.Patients and Methods: Three hundred and ninety transplant candidates (237 males and 153 females) participated in this study. Arterial blood gas oxyhemoglobin SATURATION (SaO2) was recorded and compared with pulse oximetry oxyhemoglobin SATURATION (SpO2) results for each participants. The area under the curve (AUC) of receiver operating characteristic (ROC) curves was calculated by means of nonparametric methods to evaluate the efficacy of pulse oximetry to detect hypoxemia.Results: Roc-derived SpO2 threshold of ≤94% can predict hypoxemia (PaO2<60 mmHg) with a sensitivity of 100% and a specificity of 95%. Furthermore, there are associations between the ROC-derived SpO2 threshold of ≤97% and detection of hypoxemia (PaO2<70 mmHg) with a sensitivity of 100% and a specificity of 46%. The accuracy of pulse oximetry was not affected by the severity of liver disease in detection of hypoxemia.Conclusions: Provided that SpO2 is equal to or greater than 94%, attained from pulse oximetry can be used as a reliable and accurate substitute for the ABG measurements to evaluate hypoxemia in patients with end stage liver disease.

Background: Colonoscopy is a valuable diagnostic method that patients are not willing to undergo because of the fear of its complications. The purpose of this study was to determine the effect of intravenous FLUID therapy prior to colonoscopy on blood circulation parameters and pain in patients and duration of Colonoscopy. Materials and Methods: This randomized clinical trial was conducted on 60 patients referred to the Endoscopic Department of Ghaem Hospital in Mashhad in 2016. Elderly people were randomly assigned to two groups of 30 as control and intervention groups. Patients in the intervention group received one liter of solution 1/3 normal saline, 2/3 D5W, one hour before colonoscopy. Before and 1, 3, 5, 9, and 10 minutes after colonoscopy, arterial blood oxygen SATURATION, heart rate, and blood pressure in both groups were measured and recorded in the checklist. 2 hours later, the patients’ pain levels were measured by Circulation Parameters checklist. The numerical value of pain was measured, and the durations of colonoscopy in both groups were also measured and recorded by a timer. Results: The mean age of the patients in the intervention group was 38. 4 ± 13. 6 years and in the control group was 44. 2 ± 14. 4 years. The results of post start colonoscopy stage showed that there was a significant difference between the two groups in the mean arterial oxygen SATURATION after 5 and 9 minutes of FLUID therapy (p < 0. 001), systolic blood pressure 1 and 10 minutes after FLUID therapy (p = 0. 047), and diastolic blood pressure 5 minutes after the FLUID therapy (p = 0. 049). The mean duration of colonoscopy in the intervention group (18. 15 ± 4. 21 min) was significantly lower than the control group (22. 13 ± 5. 29 min, p = 0. 002). Also, the mean pain score 2 hours after colonoscopy was significantly lower in the intervention group (1. 53 ± 1. 65) compared with the control group (3. 26 ± 3. 24, p = 0. 010). Conclusion: The results of this study indicate the positive effect of FLUID therapy prior to the onset of colonoscopy on the patients’ circulatory parameters, the duration of colonoscopy, and the patients’ pain. Therefore, with this effective, cost-effective, and safe intervention, patients can have a better experience in performing this diagnostic test.