bluuebunny/crossref_metadata_2025 huggingface dataset:
Equivalent Circulation Density Optimization: Can Flow Regimes Significantly Affect the Relationship Between Equivalent Circulation Density and Flow Rate?
Authors: Al-Hameedi Abo Taleb , Alkinani Husam H. , Dunn-Norman Shari , Al-Alwani Mustafa A. , Lian David
Published: October 2019

Flow rate (Q) affects many drilling operations and parameters such as equivalent circulation density (ECD), hoisting and lowering the drillstring, and breaking gel strength during circulation. The aim of this work is to understand the relationship between ECD and Q based on flow regimes (e.g. laminar, transitional, and turbulent) to avoid or at least minimize the unwanted consequence during drilling practice.

Field data from over 2000 wells drilled in Iraq were collected and analyzed to identify the physical relationship between flow regimes and ECD to enhance the drilling rates. After visualizing the whole dataset, a decision was made to break down the data into three parts based on flow regimes (e.g. laminar, transitional, and turbulent). Descriptive data mining techniques were utilized to establish the relationship between flow regimes and ECD. By achieving better control of ECD in the well, not only faster and cheaper operations are possible, but also safety will be improved.

Previous studies and literature showed that flow regimes can tremendously affect ECD. Many studies have been conducted to understand the relationship between Q and ECD. Nevertheless, the consideration of flow regimes was not implemented in these studies. Inconsistency in the literature results was identified, some concluded the relationship between Q and ECD to be direct, and others showed it to be inverse. Thus, this paper will eliminate this discrepancy in the literature, and it will show that the flow regimes have a pivotal role in the relationship between Q and ECD.

The results of this paper showed that if the flow regime is laminar, the relationship between ECD and Q is inverse. However, in transitional and turbulent flow regimes, the relationship between ECD and Q is direct. That is because, in the laminar flow regime, the cutting will fall out of suspension due to low Q, which will cause a cutting bed to be built and decreases ECD. As Q increases (entering the transitional and turbulent flows) the cutting bed will be eroded, and most of the cuttings will be suspended in the fluid which will increase ECD.

This study examines and expands the understanding between how the characteristics of flow regimes affect ECD. Additionally, this paper will eliminate the discrepancy in the literature about this relationship between ECD and Q.
Investigation of Rock Properties of the Marcellus Formation – An Experimental Study
Authors: Khalil Rayan , Emadi Hossein , Elwegaa Khalid
Published: October 2019

The Marcellus formation has begun to attract more attention from the oil and gas industry. Despite being the largest shale formation and biggest source of natural gas in the United States, it has been the subject of little research. To fill this gap, this study experimentally examined the rock properties of twenty core samples from the formation.

Five tests were performed on the core samples: X-ray computerized tomography (CT) scan, porosity, permeability, ultrasonic velocity, and X-ray diffraction (XRD). CT-scans were performed to identify the presence of any existing fracture(s). Additionally, helium was injected into the core samples at four different pressures (100 psi, 200 psi, 300 psi, and 400 psi) to determine the optimal pressure for porosity measurements. Complex Transient Method was employed to measure the permeabilities of the core samples. Ultrasonic velocity tests were conducted to calculate the dynamic Young's moduli (E) and the Poisson's ratios (ν) of the core samples at various confining pressures (in increments of 750 psi between 750 psi and 4,240 psi). Finally, the mineralogical compositions of the core samples were determined using the XRD test.

The results of the CT-scan experiments revealed that seven core samples contained fractures. The porosity tests yielded an optimal pressure of 200 psi for porosity measurement. The measured porosities of the samples were between 6.43% and 13.85%. The permeabilities of the samples were between 5 nD and 153 nD. The results of the ultrasonic velocity tests revealed that at the confining pressure of 750 psi, the compressional velocity (Vp) ranged from 18,411 ft/s to 19,128 ft/s and the average shear velocities (Vs1 and Vs2) ranged from 10,413 ft/s to 11,034 ft/s. At the same confining pressure, the Young's modulus and Poisson's ratio ranged from 9.8 to 10.8 million psi and 0.25 to 0.28, respectively. Increase in the confining pressure resulted in increases in the Vp, Vs, Young's moduli, and Poisson's ratios of the samples. The results of the XRD test revealed that the samples were composed of calcite, quartz, and dolomite.

This study is one of the first to characterize core samples obtained from the formation outcrop by performing five tests: CT-scan, porosity, permeability, ultrasonic velocity, and XRD. The results provide detailed insights to researchers working on the formation rock properties.
Estimating Diffusion Coefficients of Shale Oil, Gas, and Condensate with Nano-Confinement Effect
Authors: Du Fengshuang , Nojabaei Bahareh
Published: October 2019

Molecular diffusion plays an important role in oil and gas migration and transport in tight shale formations. However, there are insufficient reference data in the literature to specify the diffusion coefficients within a porous media. This study aims at calculating diffusion coefficients of shale gas, shale condensate, and shale oil at reservoir conditions with CO2 injection for EOR/EGR. The large nano-confinement effects including large gas-oil capillary pressure and critical property shifts on diffusion coefficient are examined. An effective diffusion coefficient that describes the diffusion behavior in a tight porous solid is estimated by using tortuosity-porosity relations as well as the measured shale tortuosity from 3D imaging techniques. The results indicated that nano - confinement could affect the diffusion behavior through altering the phase properties, such as phase compositions and densities. Compared to bulk phase diffusivity, the effective diffusion coefficient in a porous shale rock is reduce by 102 to 104 times as porosity decreases from 0.1 to 0.03.
Use of a New Well Productivity Model and Post-Frac Rate-Transient Data Analysis to Evlauate Production Potential of Refracturing Horizontal Wells in Shale Oil Reservoirs
Authors: Yang Xu , Guo Boyun , Zhang Xiaohui
Published: October 2019

Production data and analytical models derived from coupling the linear flow in the reservoir and the linear flow in hydraulic fractures were used in this study to optimize fracture spacing for maximizing productivity of shale oil and gas wells through refracturing. This study concludes that productivity of multi-fractured horizontal wells is inversely proportional to the fracture spacing. The shortest possible fracture spacing should be used to maximize well productivity through refracturing. This supports the practice of massive volume fracturing where as many as perforation clusters with the shortest possible spacing are used for pumping massive proppant into the created hydraulic fractures. Production data analysis indicates that the multi-fractured horizontal oil and gas wells could have higher productivity if they were fractured with less perforation cluster spacing. Mathematical model analysis implies that reducing the cluster spacing from 70 ft to 15 ft through refracturing can doubled well productivity, with the Minimum Required Cluster Spacing (MRCS) determined by well completion constraints (packers, perforation clusters, and casing couplings). Result can be checked for fracture trend interference on the basis of analyses of pressure transient data or production data.
New Friction Reducer Boosters Enhance Friction Reduction and Proppant Transport: Case Studies - Superlaterals
Authors: Xu Liang , Ogle James , Collier Todd , Straffin Ian , Dubois Teddy , Nichols Rome , Uka Oeklers Delvina
Published: October 2019

Friction reducer (FR) performance has been enhanced by adding a FR booster in both fresh water and up to 100% high total dissolved solids (TDS) produced water during hydraulic fracturing applications. However, it is not well understood how the boosters actually increase FR performance during pumping and the effects they have on surface treating pressure and proppant transport. Both laboratory results and field studies of FR and boosters are discussed. Additionally, it was observed that tailored booster chemistry appears to increase FR viscosity significantly, thereby helping ensure better proppant transport during fracturing.

Flow loop and viscosity tests were conducted to demonstrate the benefits of using a booster and the results were analyzed to understand the potential mechanisms that dictate the observed phenomena. Laboratory results suggest that the FR booster enables rapid hydration and inversion of FRs, which typically results in decreased treating pressure to approximately 800 psi compared to FRs without boosters. This pressure decrease during pumping for a single fracture stage has been frequently observed in several shale plays, such as the Wolfcamp, the STACK/SCOOP, and the Marcellus/Utica. A lower FR concentration can be used to transport proppant because the booster helps reach the same or higher viscosity. Case studies are discussed to further understand the synergy between FRs and boosters.
Artificial Intelligence Assisted Hydraulic Fracturing Design in Shale Gas Reservoir
Authors: He Qin , Zhong Zhi , Alabboodi Maher , Wang Guochang
Published: October 2019

Hydraulic fracturing is a typical and vital technique applied in shale gas reservoir development. Numerical simulation used to be a common tool to optimize the parameters in hydraulic fracturing design determining the stage numbers, injection pressure, proppant amount, etc. However, the current understanding of shale gas storage and transport mechanism (e.g. adsorption/desorption, diffusion) is basically adopted from the lessons learned from coal seams through past experience, which might not help an efficient numerical simulation development.

In this study, how artificial intelligence assisted data driven models assist the hydraulic fracturing design in shale gas reservoir is discussed. It starts by collecting field data and generate a spatial-temporal database including reservoir characteristics, operational/production information, completion/stimulation data and other variables, Neural Network models are then developed to study the impacts of all parameters on gas production as well as perform history matching of the field history. The AI assisted model with acceptable matching of field data can be used to model different hydraulic fracturing design scenarios and provide predictions on well production.
Evaluating Completion Design Efficacy Using Poroelastic Pressure Responses in Offset Wells
Authors: Das Paloma , Kahn Charles , Coenen Erica
Published: October 2019

Operators continue their quest to better understand and design completion strategies to maximize reservoir contact and optimize well spacing. This paper presents a case study that analyzes completion design effectiveness, using pressure data acquired from isolated monitor stages on offset wells during treatment of adjacent wells. The method was employed on three wells of a seven-well pad in the Marcellus, to assess fracture growth and evaluate the performance of employing intra-stage and inter-stage diversion.

Poromechanically-induced pressure responses on isolated monitor stages on offset wells during treatment of an adjacent well, are compared to a fully coupled, three-dimensional, finite element effective stress model, to calculate dominant fracture geometries that correspond to the pressure response induced in the rock. The initiation points and ascending magnitudes of the responses approaching the isolated monitor stage qualify the performance of inter-stage diversion, whereas the fracture growth trends and geometries speak for the efficacy of the intra-stage diversion and overall stage design.

The first well utilized inter-stage diversion and dissolvable plugs to isolate stages; the second well utilized intra-stage diversion to improve cluster efficiency with regular frac plugs for zonal isolation; and, the third well employed regular frac plugs with no use of diversion. This presented a unique opportunity to compare and analyze the fracture growth rates, trends, and geometries, while applying inter-stage diversion and frac plug completion designs for zonal isolation on the same pad.

This paper is a comparative study to understand the value of using inter-stage diversion, along with dissolvable plugs in place of composite frac plugs, after every stage to attain zonal isolation. In addition, completed stages utilized different fluid designs, providing the opportunity to analyze the impact of fluid design on fracture growth trends and diverter performance. The results are interpreted using pressure data-derived fracture maps with production data, which point to the performance of various completion strategies, using an entirely new diagnostic method.
Developing a New Workflow to Study the Effect of Soaking Process on Shale Well
Authors: Ibrahim Ahmed Farid , Ibrahim Mazher , Pieprzica Chester
Published: October 2019

The most common stimulation technique of shale gas production is multistage hydraulic fracturing. However, the implementation of the technique brings in new formation damage considerations. Large quantities of water-based fracture fluids, over 75% of the injected volume, usually left unrecovered at the start of production that leads to permeability reduction and low productivity. Accidently, some operators found an improvement in gas recovery after shut in the wells after flowback due to pipeline restriction. They called this behavior as the soaking effect.

This study presents a workflow to evaluate the effect of the soaking process on the well performance after the hydraulic fracturing process in actual field cases. Waterflow back analysis was conducted for 21 well to estimate the effective fracture volume before and after the soaking process. Rate transient analysis (RTA) was conducted on the production data to estimate the stimulated reservoir volume (SRV) in each well. SRV and the enhanced recovery were correlated to the soaking time. Decline curve analysis for water and gas flow rates were conducted to estimate the estimated ultimate gas and water recovery (EURg, and EURw) before and after the soaking process.

An increase in the gas flow rate was observed with soaking time with low water production. SRV increased with the soaking process up to 53% of its initial value with shut-in the well for 180 days. EURw decreased by 52 % of its value before the soaking process, while EURg increased by 48%. Shut-in the well before gas-kick off after hydraulic fracturing operations negatively impact the well performance and the gas production can decrease by 22% even after soaking process for 315 days.

This study will present a methodology to evaluate the soaking process, and recommendations to improve the impact of the soaking process on well performance.
Extended Lateral Solutions for an Extremely Difficult Well Trajectory
Authors: Albert Larry , Booher Jason , Wilson Anthony , Hamilton Fraser , Hradecky Jason , Dunning Dustin , Pratosov Vadim
Published: October 2019

An E&P operator was developing a reservoir and planned a horizontal well in an area where zones above the target cause drilling problems when trying to build angle and land the horizontal lateral. The operator suffered drilling difficulties on offset wells; therefore, it was decided to change the drilling plan for this prospect. The new plan required drilling through the target reservoir, into the formations below and then drill back up dip to the target. After reaching the base at a measured depth of 14,000 ft. the well plan required drilling up at maximum of 114° until reentering the target reservoir. Because of faulting in the area and required well direction, the target reservoir was dipping up at ∼10° laterally in the direction of the horizontal drilling target. To maintain position in the reservoir, the well had to drilled at ∼100° deviation to a measured depth of 21,100 ft.

This wellbore trajectory made normal wireline plug and perforating completion operations extremely difficult. The wellbore trajectory meant high frictions on the wireline when coming off bottom. Also, due to the toe-up trajectory there was risk the wireline tools would slide down the inclined casing during and after plug setting and perforating. If the tool position could not be maintained there was risk the wireline cable could be entangled and a stuck tool could result. If the tools overrun the wireline cable the result could be wireline cable next to the perforating guns when detonated and wireline cable severed. The E&P operator needed to know if this challenge could be met.

Alternatives to pump down plug and perforating could be very expensive (estimated $millions): Abandon acreage,Continue drilling attempts building angle above the target,Reposition surface location and drill down dip,Reduce angle and shorten lateral in target, orCoiled tubing conveyed plug and perforating completion.

To meet the challenge several new methods and technologies developed for extended laterals were utilized. These products and methods included: advanced risk deployment modeling, jacketed wireline cable, addressable separation tool and downhole tension tool.
A New Gas-Content-Evaluation Method for Organic-Rich Shale Using the Fractionation of Carbon Isotopes of Methane
Authors: Cao Gaohui , Zhang Huanxu , Jiang Wenbin , Wu Sheng , Zhu Di , Lin Mian
Published: October 2019

Gas content is a key parameter for the determination of the gas resources in unconventional reservoirs. In this study, we propose a novel method to evaluate the gas content of shale through a new perspective: fractionation of carbon isotopes of methane. At first, a bicomponent gas–convection/diffusion/adsorption model (BG–CDAM) is successfully built with consideration of the flow and adsorption difference between 13CH4 and 12CH4 in the nanoporous shale. A detailed understanding of the mechanism of fractionation of the isotopes is obtained for the first time and the Knudsen–diffusivity difference is identified as the dominant factor for fractionation according to the different molecular weights of the isotopes. Then, the simulated results of BG–CDAM and the measured data from an isotope–logging test are combined to determine the unknown parameters for gas–content calculation. The proposed method for organic shale is valid and useful to obtain the quantitative component proportion in gas content, such as lost gas, degassing gas and residual gas, or free gas and adsorption gas. Thus, this method could provide a promising means for the identification of sweet spots in shale–gas reservoirs. Moreover, the method might have the potential to economically and rapidly evaluate the remaining resources in producing wells in future applications.
Advanced Surveillance Technique for Multi-Phase Sweep Efficiency Monitoring
Authors: Al-Qasim Abdulaziz , El Sheshtawy Mohamed , Kokal Sunil , Benlakhdar Noureddine
Published: October 2019

With maturing oil fields there is an increasing focus on improving the oil recovery factor and pushing the envelope toward a 70% target. This target is indeed very challenging and depends on a number of factors including enhanced oil recovery (EOR) methods, reservoir heterogeneities, displacement efficiency, and reservoir sweep. Other factors also play a role including vertical sweep due to flow behind the casing, well integrity issues, presence of conductive faults, or fractures. Proper surveillance performed to evaluate the injectant plume front, reservoir conformance, well connectivity, assessment of the integrity of wells, and other factors can be crucial for the success of the project and its future development.

The paper discusses special downhole logging techniques including a set of conventional multiphase sensors alongside high precision temperature (HPT) and high-definition spectral noise logging (SNL-HD). It was run to provide complete assessment of the injection – production distribution and any associated well integrity issues that might impair the lateral sweep of injectants into the target layer. This will be done for an injector and producer pair near the wellbore area. The operation was carried out with a tool string that contained no mechanical parts and was not affected by downhole fluid properties. It was conducted under flowing and shut-in conditions to identify flow zones and check fracture signatures. It also provided multiphase fluid velocity profiles.

The results of the survey allowed for in-depth assessment of borehole and behind casing flow, confirming lateral continuity, and provided an assessment of production-injection outside the pay zone. Results will allow for better well planning and anticipation of possible loss of well integrity that might impair production in the future. Combining the behind casing flow assessment with borehole multiphase flow distribution can be used for production optimization by sealing unwanted water contributing zones.
Low-Salinity Polymer Flooding in a High-Temperature Low-Permeability Carbonate Reservoir in West Kuwait
Authors: Al-Murayri Mohammed Taha , Kamal Dawood S. , Al-Sabah Hessa M. , AbdulSalam Tareq , Al-Shamali Adnan , Quttainah Riyad , Glushko Dan , Britton Chris , Delshad Mojdeh , Liyanage Jith , Dean Robert Matthew
Published: October 2019

While polymer flooding has widely been used as a successful technology to improve mobility control and sweep efficiency in many oil reservoirs, its applicability under harsh temperature/salinity conditions and in low-permeability reservoirs has prohibitively remained a challenge.

This study was aimed at investigating the feasibility of low-salinity polymer flooding in a very challenging reservoir located in Kuwait with low permeability (< 10 mD), high temperature (113°C), high salinity (~239,000 ppm), high hardness (~20,000 ppm), and carbonate mineralogy. The evaluation was conducted through a series of systematic laboratory studies including polymer rheology, thermal stability, and transportability using coreflood tests.

Our results highlight that the common constraints may be overcome by careful selection of polymer/cosolvent/pre-shearing and appropriate design of low-salinity polymer flooding.
High Throughput Catalyst Testing to Enhance Refinery Operations
Authors: Hakeem Abrar
Published: October 2019

An important aspect of refinery and petrochemical complex(s) are the catalytic units without which many processes are not possible. Catalyst selection in a refinery or petrochemical complex has a big impact on the yields, energy usage and provides with a competitive advantage by selection of better performing catalyst for the actual feedstock. To perform catalyst section, a comparative catalyst testing on a smaller scale unit is required. Previously, it used to be performed in a single flow conventional reactor unit, which is time consuming, non-effective and laborious in comparing more than two types of catalysts. As conventional catalyst testing takes long time, catalyst selection in refinery is often based on information shared by a Catalyst Vendor referred as "paper assessment". However, the use of high throughput technology enables accelerated catalyst testing (faster results) and facilitates the selection of the best catalyst in alignment with the timeline faced by the refinery in decision-making process. This enables identification of the best catalyst from different vendors based on actual performance of the catalyst and has a great potential to enhance operations. In addition, the use of high throughput catalyst testing unit enables opportunities with different experimental designs to develop kinetic models, to simulate reactors in series and to do stability tests in an effective manner.
Black Powder Removal from Oil Pipelines
Authors: Balhasan Saad , Omar Mohammed , Alhamoudi Hassan , Alzaabi Abdulrahman , Abdelwahab Salma
Published: October 2019

Of the total oil and gas supply, a significant share is transported through pipelines. Ultimately the level and quality of cleanness of pipelines greatly affect the transportation of oil and gas. Considering this, any obstacle in the pipelines will delay the transportation process and will consequently reduce the amount of oil and gas transported at a high cost. Remarkable issues that are related to black powders are the contamination of product, reduction in flow of oil and gas, and environmental hazards.

The main objective of this paper is to gain familiarity with the phenomenon of black powder, and based on the analysis design and builds a magnetic Nanoscale filtration/sorption system for crude oil treatment. A magnetic separation system is used for removal of iron and heavy metals from crude oil. The prime function of the radial field magnetic separation system is the breaking-down of black powder particles to submicron levels in full flow. Moreover, the paper has studied the enhancement of nanoparticle technology by using the graphene nanoparticles to improve the separation efficiency of the magnetic separation system. The graphene nanoparticles have enhanced the magnetic separation system. The resistivity meter has been used to measure the resistance of the oil, before being contaminated with black powder and after, in each step of the experiment. It has been observed that higher resistance leads to lower values of black powder.

The analysis suggests that one stage of magnetic separation is more efficient than two stages. Measurement shows that with one stage magnetic separation procedure, the resistance of the oil sample, with black powder, increased from 2157 kΩ to 2969 kΩ, before and after the magnetic separator. The separation of black powder has estimated by 22%, and the magnetite material decreased by 16 gm. However, the resistance of the oil sample, with graphene nanoparticles, increased from 1799 kΩ to 2661 kΩ, before and after the magnetic separator. The separation of black powder has estimated by 24%, the amount of the magnetite material decreased by 19.58 gm. The 2% increase in the efficiency of the system can be attributed to the use graphene nanoparticles.
Investigation of Low Salinity EOR: Application for Kuwaiti Reservoir
Authors: AlAmer Rawan , Al Ajmi Abdullah , Al Qahtani Mesferah , Gharbi Dr Ridh
Published: October 2019

This paper investigates the applicability of Low Salinity (LoSal) EOR for a Kuwaiti reservoir. Many reservoirs in the Middle East are not producing satisfied results after depletion methods for a long time of production. Therefore, new management and production strategies must be determined in order to meet the global market demand for oil, which can be done using Enhanced Oil Recovery (EOR) techniques. In Kuwait, one of the EOR methods that could be applied is the use of Low-Salinity (LoSal) Water Flood.

Results from previous research have clearly shown that LoSal water injection has a significant impact on oil recovery. Although there are many LoSal experimental results reported in the literature, the process mechanisms and the prediction modeling are yet to be fully investigated and understood. As a result, further experimental work is needed in order to be able to develop reliable prediction tools.

The research in this paper is an integrated study combining laboratory work to assess the performance of LoSal water flood using live crude, reservoir brine and native core with wettability conditions restored. The core flooding phase will conduct series of low salinity water flood experiments, design of Salt type and concentration. The performance of LoSal will be compared to different salinities water flood based on reservoir water salinity.
Optimizing Production using Nodal Analysis Applications
Authors: Al-Qasim Abdulaziz , Almudairis Fahad , AlAbdulatif Ziad , Alsubhi Mutaz
Published: October 2019

Optimizing the development of oil and gas fields necessitates the use of accurate predication techniques. The predictions should also involve minimizing the uncertainties associated with day-to-day operational challenges related to wells, pipelines and surface facilities. The choke size settings, for instance, need to be frequently adjusted to optimize production flowrates using the right techniques.

This paper provides a method to optimize the production flowrate for existing wells and to minimize the cost through finding the best cost-effective selection. Providing an insight into factors affecting the flow assurance of oil and gas reservoirs is also included. The study has been implemented by the use of nodal analysis conducted by a surface network simulation, to reach the optimum design of oil and gas production systems. The optimization of the wells can be achieved by changing tubing and flowline sizes, minimizing the skin factor, controlling the water cut, and adjusting the gas-lift injection pressure.

The Hurricane oil field that covers a wide range of subsurface and surface facility data is simulated in this paper. Seven reservoirs are considered in this study containing eleven different wells. Seven of these wells are producing naturally while the remaining four wells are gas-lifted. For each of the eleven wells, different parametric scenarios are run on the different size of the pipelines and chokes. Flow assurance study has been conducted to know the effect of severe slugging, wax deposition, and hydrate formation. Severe slugging has been predicted using a surface network simulation, while wax deposition and hydrate formation using a pressure-volume- temperature (PVT) simulation. For the artificial lift wells, as this field was mainly operated by gas lift, a new design has been implemented based on gas surface injection rate as a way to eliminate the workover operations.
Root Cause Analysis for Iron Sulfide Deposition in Sour Gas Wells
Authors: Chen Tao , Wang Qiwei , Chang Frank , Leal Jairo , Espinosa Mauricio
Published: October 2019

Iron sulfide (FeS) deposition is a ubiquitous phenomenon in sour oil and gas wells, especially for these producing from high temperature and high pressure reservoirs. Hydrogen sulfide (H2S) gas is highly soluble in water and readily reacts with carbon steel and dissolved iron once in contact, which leads to the formation of FeS scale. The surface deposition or bulk precipitation of FeS scale is detrimental to flow assurance, such as flow restriction, pitting corrosion and stabilized emulsion.

Compared to the conventional carbonate and sulphate scales, the mitigation of iron sulfide deposition is notoriously difficult. It is essential to understand its root causes in order to develop a suitable strategy to manage the problem effectively.

By combining laboratorial tests and model simulations, new progresses have been made on the FeS root cause analysis for high temperature high H2S gas wells. The iron sources were determined over different stages of well life from drilling, completion, acidizing to production.

Results from this study demonstrate that the iron contributed by the sour reservoir connate water is limited and is not the major cause to FeS deposition on downhole tubular in sour gas wells. Carbon steel corrosion during production stage is one source of FeS deposition. However, the rate of iron sulfide deposition during production is minor and far less than the deposit observed in the field. Other sources of iron sulfide deposition should be further investigated.

Another major source is the iron released from tubing due to acid corrosion during acidizing stimulation, which potentially leads to severe formation damage and associated deposition problems in the production tubing and equipment. In addition, the iron contamination in the drilling fluid could contribute to FeS scaling problem.

This paper presents a fundamental study to understand the sources of iron for FeS deposition in high H2S sour wells producing from carbonate reservoirs. Appropriate mitigation strategies are recommended accordingly.
Practical Solutions for Rate-Transient Analysis of Tight/Shale Reservoirs with Interfracture Induced Heterogeneity
Authors: Sureshjani Mohammadhossein Heidari , Ahmadi Mohammad , Fahimpour Jalal
Published: October 2019

Production from previously uneconomic tight/shale formations has become feasible by constructing multifractured horizontal wells. Rate-transient analysis of these wells is commonly performed with the assumption of homogeneous-reservoir models, which might not be valid in reality. During hydraulic fracturing, secondary fractures might be formed in the reservoir. Because of the limited energy of hydraulic fracturing, the quality of secondary fractures decreases with the distance from the main fracture. This would negate the assumption of a homogeneous reservoir.

In this paper, we present practical solutions that include reservoir heterogeneity in rate-transient analysis of multifractured wells. The solutions are developed for transient linear flow, which is a dominant-flow regime in many tight/shale reservoirs. In addition to forward solutions, inverse solutions are also developed that would ease the analysis procedure and reduce the uncertainty of estimation. The solutions are presented in simple formats and can be easily applied. We first developed the solutions such that they can be applied for any arbitrary permeability profile. We further considered special formats for the permeability/distance relationship and developed the relevant models. For a homogeneous system, the well-known square-root-of-time (time to the power of 0.5) plot is used. For the case of heterogeneity, however, the power of time should be greater than 0.5 and less than unity to produce a straight-line plot. We mathematically demonstrate this for a recognized format of the permeability/distance relationship.

The presented solutions are verified with the numerical simulation of synthetic examples. Comparison of the results reveals the accuracy of the analytical solutions. Two field examples are also analyzed to indicate the practical applicability of the analytical solutions. The permeability/distance profiles for these field examples are derived using the inverse solutions.
The pregnancy intention to have a second child and antenatal depressive symptoms in Chinese women under the new two-child-per-couple policy
Authors: Xiao Meili , Fu Bing , Mi Chunmei , Pan Chen , Zhu Shujuan , Lei Jun
Published: October 2019

Background: Few studies investigated the association between the pregnancy intention to have a second child and antenatal depressive symptoms.The aim of this study was to explore the association between the pregnancy intention to have a second child by pregnant women’s own desires, pregnant women’s husband own desires, parents who want to grandchild desires, couple’s concordance desires and antenatal depressive symptoms. Methods: A total of 306 participants who completed questionnaire were included in our analysis. Antenatal depressive symptom was assessed using the Chinese version of Edinburgh Postnatal Depression Scale. Logistic regression models were used to estimate the association between the pregnancy intention to have a second child by pregnant women’s own desires, pregnant women’s husband own desires, parents who want to grandchild desires and antenatal depressive symptoms. Results: the prevalence of antenatal depressive symptoms was 36.3% among the second child pregnant women. Of the 306 participants, the proportion of the pregnancy intention to have a second child by pregnant women’s own desires, pregnant women’s husband desires, parents who want to grandchild desires and couple’s concordance desires was 8.5%, 8.5%, 10.8% and 72.2% respectively. Compared with the pregnancy intention by couple’s concordance desires, pregnant women’s own desires to have a second child had higher risk of antenatal depressive symptoms after adjustment for potential confounders (OR=4.560, 95%CI: 1.603,12.973). No association was found between the pregnancy intention to have a second child by pregnant women’s husband own desires, parents who want to grandchild desires and antenatal depressive symptoms after adjustment for confounders (OR=1.996, 95%CI:0.781,5.105; OR=0.744, 95%CI: 0.306,1.811, respectively). Conclusion: These findings suggest the pregnancy intention to have a second child by pregnant women own’s desires may be a risk factors for antenatal depressive symptoms among two-child pregnant women. A qualitative study should be carried out to investigate the real reason for the intention by pregnant women’s own desires and antenatal depressive symptoms in the future, because of this study was a quantitative study. Key words: pregnancy intention; antenatal depressive symptoms; second child
Timely initiation of postpartum contraceptive and associated factors among women of extended postpartum period in Pawe district, northwest Ethiopia, 2019
Authors: Jaleta Desalegn Nazi , Yeshita Hedeja Yenus , Tamirat Koku Sisay
Published: October 2019

Background: Postpartum family planning is an important intervention for reducing high risk fertility behavior and spacing birth intervals; which ultimately helpful for the health of mothers and their babies. Hence, this study aimed to determine the magnitude of timely initiation of postpartum contraceptive and associated factors among extended postpartum women in Pawe district, Northwest Ethiopia.Methods: Community based cross-sectional study design was employed from February to March 2019 in Pawe district. A stratified multistage sampling technique was used to select a total of 820 women in the extended postpartum period. Data were collected using a pretested interviewer administered questionnaire. A bivariable and multivariable logistic regression model was fitted to identify determinants of timely initiation of postpartum contraceptive among extended postpartum women. Adjusted Odds ratio (AOR) with 95% CI was computed to assess the strength and presence of an association. Variable with less than 0.05 p-value considered as a significant determinant of contraceptive initiation.Results: Out of the total participants about 37.2% [95% CI (34.0, 40.5)] initiated postpartum contraceptive. Time return of menses [AOR=18.32, 95% CI(11.66,28.80)], postnatal care [AOR=7.8, 95%bCI(3.98,15.44)], knowledge level regarding modern contraceptive methods [AOR=3.0, 95% CI(1.40,6.59)], time of resumption of sexual intercourse [AOR=2.1, 95% CI(1.327,3.21), husband approval to use contraceptive [AOR=2.45,95%CI(1.42,4.22), antenatal care [AOR=2.1,95% CI(1.13,3.76), place of delivery at institution [AOR=2.0, 95% CI(1.22,3.39)], and got family planning counseling at delivery [AOR=2.34, 95% CI(1.22,4.49)] were factors associated with timely initiation of postpartum contraceptive. Conclusion and recommendation: The magnitude of timely initiation of postpartum contraceptive was low. This suggests strengthening the integration of postpartum contraceptive use with other basic maternal health services and improving knowledge of women in practicing timely initiation of postpartum contraceptive before engagement to risk activities of unintended pregnancy is important.
Application of Light-emitting Diodes and the Effect of Light Quality on Horticultural Crops: A Review
Authors: Zheng Liang , He Huaming , Song Weitang
Published: October 2019

Plant growth and development relies on light and is influenced by light. Light-emitting diode (LED) technology is nowadays providing the possibility for regulating plant growth and development by modifying light spectral composition. Many researches have been carried out to figure out the effects of light quality on various aspects of plant behaviors, including plant morphology, physiology, and biochemistry. In this review, we summarized those research outputs, in order to give suggestion of light quality application for both research and production purposes, in the field of productional yield, productional quality for horticultural plants including vegetables or ornamentals in difference with cultivation goals.
Unfrustrating the t-J Model: Exact d-wave BCS Superconductivity in the t'-J_z-V Model
Authors: Slagle Kevin
Published: October 2019

The t-J model is believed to be a minimal model that may be capable
of describing the low-energy physics of the cuprate superconductors.
However, although the t-J model is simple in appearance, obtaining a
detailed understanding of its phase diagram has proved to be
challenging. We are therefore motivated to study modifications to the
t-J model such that its phase diagram and mechanism for d-wave
superconductivity can be understood analytically without making
uncontrolled approximations. The modified model we consider is a
t’-J_zJz-V
model on a square lattice, which has a second-nearest-neighbor hopping
t’ (instead of a nearest-neighbor hopping t, an Ising (instead of
Heisenberg) antiferromagnetic coupling J_zJz,
and a nearest-neighbor repulsion V. In a certain strongly interacting
limit, the ground state is an antiferromagnetic superconductor that can
be described exactly by a Hamiltonian where the only interaction is a
nearest-neighbor attraction. BCS theory can then be applied with
arbitrary analytical control, from which nodeless d-wave or s-wave
superconductivity can result.
Promotion of Ukraine’s export to China: priorities and institutional framework
Authors: Melnyk Tetiana , Kudyrko Ludmyla , Pugachevska Kateryna , Sevruk Iryna
Published: October 2019

In the context of neo-protectionism and in terms of WTO membership, regulatory mechanisms for promoting the national producer and country’s external expansion require an institutional basis. This paper primarily aims to explore the resource and institutional component in promoting Ukraine’s exports to Chinese market and to identify the level of Ukraine’s export promotion system effectiveness based on combinatorial approach, which includes the calculation of quantitative indicators of foreign trade in the form of international production and marketing cooperation and estimation of qualitative parameters of export promotion effectiveness. The empirical findings indicate following: high dynamism of increasing mutual trade volume; enlargement of trade flows asymmetry caused by the negative trade balance of Ukrainian economy; limited list of commodity groups of Ukrainian exports in mutual trade with China with stable relative advantages; dominance of low-value-added commodities among export priority groups; absence of beneficial effect of such a factor as “long-term partnerships” in the mutual trade flow. The paper reveals that national export promotion system in Ukraine can be characterized by low efficiency and strong potential for growth. The authors emphasize the importance of intensifying the projects and mechanisms of financial and investment support for exporters with increasing the level of their innovative orientation. Prospects for further research in this area are as follows: the assessment of macroeconomic effects from the introduction of export promotion tools for the national economy of countries of origin of goods and importing countries; detection of anticompetitive risks in the implementation of selective support programs for exporters.
Problems of risk communication: methodological approaches to the use of sociological data in planning of information work with the population on radiation safety issues
Authors: Repin L. V. , Biblin A. M. , Vishnyakova N. M. , Sokolov N. V. , Davydov A. A.
Published: October 2019

Publications of the IAEA, ICRP, the Decree of the President of the Russian Federation of October 13, 2018 No. 585 “On the Approval of the Basic Principles of State Policy of the Russian Federation in the Field of Nuclear and Radiation Safety until 2025 and beyond” emphasize the increasing role of public in decision-making in the use of ionizing radiation. Sociological research is a part of the preparatory stage in the organization of interaction with stakeholders. During that stage, the participants in the information interaction (stakeholders) have an opportunity to study each other’s attitudes, so that the interaction is as constructive as possible. Sociological studies allow to determine the positions of stakeholders on the subject of risk communication at the initial stage of the process, in the implementation of decisions and in assessing the effectiveness of risk communication. The basis of the sociological study is the program. In forming a sociological research program, it is necessary to pre-identify important factors that can influence the attitude to a particular management decision of different stakeholders. The main purpose of the sociological research is to study the range of opinions and features of perception of the planned management decision by various participants in the process of risk communication. In assessing sociological research, one of the main tasks is to determine the nature of possible contradictions in the positions of the stakeholders, which largely determines the willingness of the interested parties to dialogue. In the consensus risk communication, the results of sociological research are useful in the formation of three sections of information materials: general information about the event, benefit assessment, and threat assessment.
Üniversite Öğrencilerinin Film İzleme Tercihlerini Etkileyen Faktörler: Bingöl Üniversitesi Örneği
Authors: Özbey Ali Ülvi
Published: October 2019

Bu araştırma, üniversite öğrencilerinin film tercihlerini etkileyen
faktörleri araştırmaya yönelik betimleyici bir çalışmadır. Bingöl Üniversitesi
sosyoloji bölümünde eğitim gören yaklaşık 100 üniversite öğrencisi için
hazırlanan bir anket formu uygulanmıştır. Bu anket formu, öğrencilerin en çok
hangi tür film izlediklerine, ne sıklıkla sinemaya gittiklerine, film
izlemedeki temel motivasyonunu ne olduğuna dair sorular içermektedir. Ankete
verilen cevaplar betimleyici istatistiklerle ele alınmış̧ ve cinsiyet değişkenine
göre farklılaşmalar sınanmıştır.

Sonuçlar üniversite öğrencilerinin film izlemedeki temel
değişkenleri ortaya konmasının yanında o yaş aralığıyla ile ilgili entelektüel
anlamda birtakım soruların cevabına ulaşmada yol gösterici olmuştur. Ayrıca
film tercihlerinde cinsiyete göre çeşitli farklılıklarla birlikte bazı
benzerlikler de gözlenmiştir. Söz konusu bulgular ışığında, üniversite
öğrencilerinin sinema ve filmlerideki tür ve amaçları modern kültür açısından
tartışılacaktır.
Сatalytic Phosphorylation of Aromatic C-H Bonds: from Traditional Approaches to Electrochemistry
Authors: Strekalova Sofia , Khrizanforov Mikhail , Sinyashin Oleg , Budnikova Yulia
Published: October 2019

The interest in organophosphorus compounds with a C-P bond is due to their
wide use in various fields, especially in medicine and agrochemistry. Prominent examples
of anti-cancer, antibacterial, and anti-HIV agents are therapeutic candidates containing a
phosphonic acid group fragment. This review provides modern synthetic methods for obtaining
phosphorylated aromatic and heteroaromatic compounds with the participation of
complexes and salts of various metals developed in recent years as well modern protocol -
electrochemical synthesis which allows carrying out reactions at room temperature and
normal pressure with no additional oxidants or bases. Herein, we demonstrate new trends
and evolution of phosphorylation reactions in catalysis.