bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluating the Relationship Between Natural Gas Hydrocarbon Heavy-Ends Condensation and Its Hydrocarbon Dew Point HDP
Authors: Ibemere Uche , Mmata Bella , Onyekonwu Mike
Published: July 2016

Natural gas comprises of non-hydrocarbons, light and heavy-end hydrocarbons. Although heavy-end hydrocarbons, may be present in negligible concentration in dry or lean gas, its reasonable occurrence in wet or rich gas is of great concern to all stakeholders because of their ability to retrograde and coalesce into liquid or solids.

Hydrocarbon Dew Point is basically controlled by the availability and quantityof condensable heavy-end hydrocarbons in a natural gas sample. In this work, fifteen natural gas samples, collected from different flow stations and gas processing plants in the Niger Delta Region were used. In this exercise, efforts were made to establish the relationship between the liquid content of the gas or condensable hydrocarbon and the resultant measurable hydrocarbon dew point of the same natural gas sample.

The natural gas samples were analyzed by Gas Chromatographic technique in reference to ASTM D1945 (2013). The results generated were reported in gallons per thousand cubic feet (GPM) of various alkane plus fractions. HDP was measured with manual dew-scope, using ASTM D1142 as standard method. NIST 1297 and Statistical tools were used to quality-check generated analytical results.

The results of this work confirmed that there is a relationship between condensable hydrocarbons and practical hydrocarbon dew point. It also highlighted the need to employ gas chromatographic method as a tool to give a vivid picture of the condensable heavies that resulted in the measured HDP.
Evaluation of the Impact of Inter-Reservoir Communication on Resource Volume via Material Balance Multi Tank Model
Authors: Mogbolu Emmanuel , Okereke Onyedikachi , Olatope Victor , Onobrudu Portia , Olubamise Taiwo , Ukauku Ikwan
Published: July 2016

A multi-tank model is presented that was used to evaluate the volume of gas produced from an undeveloped gas reservoir as a result of sand-to-sand juxtaposition with a developed oil rim reservoir. An innovative approach of using Microsoft Excel via OpenServer to link MBAL model to history match reservoir pressures in a multi-tank model, while considering all the reservoir uncertainties was adopted. The process helps to save time in Reservoir Management.

An oil rim reservoir with future gas development seemed to be communicating with an undeveloped gas reservoir via sand to sand juxtaposition based on the pressure data taken during the drilling of one of the wells and fault seal analysis. This clearly showed depletion in the undeveloped gas reservoir.

Through a multidisciplinary approach, the two reservoirs were built into tank models and connected using a transmissibility model. The resultant model was history matched using an experimental design approach and contacts calibrated prior to running simulation and prediction.

The result showed the quantity of Gas Initially in Place (GIIP) in the undeveloped reservoir that has flowed into the developed reservoir and has possibly been produced already. This insight provides a quick analytical understanding on the resource volume impact of this phenomenon on both reservoirs with respect to their future gas development. This has led to the need for a revised development plan for both reservoirs with respect to future gas production.

The novelty of the use of experimental design with MBAL multi-tank model in this scenario is in the ability to history match the model in reasonable time. This is achieved while effectively managing reservoir uncertainties. This is critical for key business decisions on reserves booking, business planning, general reservoir management and production.
Curing Lost Circulation with an Engineered Spacer During Cement Placement
Authors: Mofunlewi Samuel S. , Okoto Francis
Published: July 2016

One of the arts of providing zonal isolation in wells is the ability of the cement to fully replace the mud system in the annulus. One way of achieving this is to pump a spacer system that can displace the mud, which means the spacer system should be able to generate enough downhole force to overcome the yield stress of the mud. To achieve effective zonal isolation, the cement spacer must remove both movable and immovable mud (that may have gelled up during static conditions) from the wellbore before cementing. To achieve this, the mud must be conditioned through circulation so that the rheological properties of the mud in and out of the well are uniform.

Challenges are usually encountered in wells where losses are experienced during drilling or while running casing. Usually, attempts are made to cure such losses before the cement job. Unfortunately, some losses cannot be cured with lost-circulation materials before the cementing operations. When such situations arise, it becomes difficult to condition the mud or circulate the mud to alter the rheological properties, as circulation can result in further break down of the formation, thereby leading to more severe losses.

A similar challenge occurred during operations for an operator in Kenya. After drilling the well to the expected total depth, during the casing run at a flow rate of 150 gpm, total losses were observed. To solve this problem, an engineered cement spacer that can cure moderate to total losses was deployed during the cementing operation. This unique spacer system can form a seal across the sand face and can be designed with rheological properties optimized to enhance the displacement of unconditioned mud.

This paper will describe in detail the unique nature of this cement spacer in curing losses as well as the mechanism with which it provides its sealing effect in permeable and fractured formations. Case studies will be presented to describe how the spacer has been used to cure moderate to total losses in oil, gas, and geothermal wells in formations with low fracture gradients and induced fractures.
A Review Study of Oil Displacement Mechanisms and Challenges of Nanoparticle Enhanced Oil Recovery
Authors: Idogun Akpevwe Kelvin , Iyagba Elijah Tamuno , Ukwotije-Ikwut Rowland Peter , Aseminaso Abiye
Published: July 2016

The utilization of nanoparticles (NPs) as an agent for improved oil recovery (IOR) and enhanced oil recovery (EOR) has attracted a lot of attention over the past decade. NPs are known to have high mechanical and thermal stability and they can be tailored to meet the specifications of a given reservoir system. As a result, as opposed to polymers, NPs are suitable options for EOR processes as they are capable of withstanding high temperatures, pressures, shear and salinity in harsh environments often prevalent in subsurface oil reservoir systems. Researchers have made promising observations and results at laboratory scale, proving that nanoparticles possess the capacity and potential to reduce residual oil in the rock matrix thus increasing ultimate recovery. NPs have been observed to lower interfacial tension (IFT), reduce the viscosity of oil and alter wettability. This study presents an in-depth review of the oil displacement mechanisms that favour nanoparticle enhanced residual oil recovery. It goes on to review the causes and effects of NP retention in porous media. Processes carried out at laboratory scale and properly designed for reservoir fluids may fail when implemented at reservoir scale as a result of geological factors. Hence the review concludes by making recommendations for successful NP EOR projects.
Spontaneous Imbibition in Niger Delta Cores
Authors: Kerunwa A. , Onyekonwu M. O. , Anyadiegwu C. I. , Olafuyi A. O.
Published: July 2016

Spontaneous imbibition is a process where the non-wetting fluid is displaced by the wetting fluid in a porous medium by means of capillary forces. Spontaneous imbibition plays a key role in oil recovery.

This paper presents experimental data for countercurrent spontaneous imbibition into cores with different porosity and permeability. Experiments were performed using Niger Delta sandstone core samples. Core samples were initially saturated with brine. Crude oil samples of different viscosities were then injected into the core samples. Synthetic reservoir brine was used as the wetting phase.

Scaling the experimental data of spontaneous imbibition with different injection fluids is crucial to properly design improved recovery methods and to predict their performances. In this work an analytical solution of a model describing counter-current imbibition was derived. Recovery curves were used for scaling the data in different cores and at different interfacial tensions. The scaling approach developed by Li and Horne yielded satisfactory correlation for all the cases. The results obtained were compared with the model we developed which also correlated satisfactorily. We also used the solutions of the model we developed to gain insight into the parameters that control oil recovery by spontaneous imbibition.
Effect of N-Vinylcaprolactam on Hydrate Inhibition in Gas Dominated System
Authors: Odutola Toyin Olabisi , Onyekonwu Mike Obi , Ikiensikimama Sunday Sunday
Published: July 2016

Sub-sea developments produce greater flow assurance and intervention challenges. Low seawater temperature may lead to hydrate formation in subsea pipelines. The effect of N-Vinylcaprolactam in preventing hydrate plug formation in gas dominated systems was studied using a 12 meter long closed loop designed for hydrate studies. The experiments were conducted by circulating gas and water at 150psi in the presence of 0.04wt% or 0.05wt% concentration of N-Vinylcaprolactam. The equivalent weight of N-Vinylcaprolactam used wasobtained based on the weight of water fed into the loop. Results showed that the loop pressure declined to 105 psi when 0.05wt% N-Vinylcaprolactam was used as inhibitor. However, when 0.04wt% of N-Vinylcaprolactam was used in the constant volume experiment, the loop pressure decline to 83psi implying that more gas was used up in forming hydrates. In the uninhibited system, the pressure declined from 150psi to 70psi and hydrate plug was noticed. This implies that at 150psi, 0.05wt% concentration of N-Vinylcaprolactam was effective at preventing hydrate formation in the experimental hydrate loop. Mathematical models describing the performance of N-VCap in the experimental loop were derived from experiments conducted. Hydrates may form in subsea pipelines in the presence of inhibitors if the appropriate dosage is not used. It is therefore important for the engineer to evaluate the effective inhibitor dosage prior to field implementation.
Model to Predict the Viscosity of Waxy Crude oil
Authors: Ketebu Promise E. , Ajienka Joseph J. , Ogbonna Joel , Ikiensikimama S. Sunday , Ukwu Austin K.
Published: July 2016

Waxy Crude Oils deposit wax at temperatures below the wax appearance temperature (WAT), thus exhibiting non-Newtonian flow behavior. In this study, the viscosity of waxy crude oils from 20 oil fields in the Niger Delta were measured for temperatures above and below the WAT using the Cannon-Fenske viscometer in line with D445 procedure on 112 viscosity data points. Of these total data points, 100 were used to develop the models and 12 were used to validate and compare the developed correlation with other correlations. Models for waxy crude oil viscosity and wax appearance temperature were developed using multiple regression analysis. The input data to the models are pour-point determined in line with ASTM D97, API obtained with ASTM E126-76 methods. The developed viscosity and WAT models have average deviations of 5.83% and 2.48% respectively.
Benefits of Robust Data Integration in Gas Cap Blow Down Phenomenon - Reservoir Life Cycle Resource Estimation Case Study
Authors: Dennar Linda , Emelle Chima , Bakare Olatunji , Etuk Ubong , Daodu Olugbenga , Ahmed Suleiman , Nwachinemere Uche , Obeahon Percy , Ukauku Ikwan , Mafe Oluwaseun
Published: July 2016

This paper provides an insight into the gains and realism injected into life cycle resource estimation of a gas cap reservoir slated for gas cap blown in 2030. Proper data integration spanning from subsurface to surface cannot be over emphasized as the major trigger for the successful estimation of the life cycle resource in this reservoir alongside a realistic execution time line for the gas cap blow down project.

One major consideration in the evaluation of gas cap blowdown projects is the efficient and maximal recovery of the oil rim available and the subsequent prediction of the gas cap blow down on stream phase while complying with statutory promises. A major enabler to achieving this objective in the ZN reservoir was the ability to harness and integrate available shared critical data from the subsurface, production, studies team, forecasting team, facilities and concept engineering teams in a pragmatic and cost effectively manner.

The ZN is the largest gas cap reservoir in the X-Onshore field. Current STOIIP is 320MMstb and GIIP is 1.4 TCF. The reservoir started production 21 years ago and a total of 13 oil wells have produced from this reservoir with two gas wells proposed to be used in the blow down of the gas cap at a future date. Cumulative oil production so far is 46MMSTB and 157BSCF AG which translates into a current oil RF of 14%.

Accurate estimation of the Gas Cap Manifold Inlet Pressure, the Gas Cap blow down on stream dates and project prioritization were key factors required for the proper prediction of the life cycle resource for this reservoir.

This paper seeks to describe how effective the process of proper data integration has been in assisting the delivery process that has translated into a more realistic and robust gas cap blow down time line and resource evaluation that synergizes with the stakeholders growth aspirations.
Comparatiive Economic Analysis on Offshore and Land-Based Liquefaction Facilities in Nigeria
Authors: Gbonhinbor Jeffrey , Adebanjo Adedotun , Oruene Azibator , Onyekonwu Michael , Ikporo Bibobra
Published: July 2016

This research examines the applicability of two possible configurations of LNG plants as a means of monetizing Nigeria's gas reserve. It involves an extensive evaluation of LNG technologies both offshore and onshore on an economic comparative basis. Economic analysis was performed on all quantitative data acquired from peer-reviewed academic journals, conference papers and technical reports. Feasible assumptions such as capacity of plants, life of projects and hurdle rate were adopted to enable a fair comparison without distortion. Cash flow analyses were conducted in relation to Nigeria's upstream natural gas utilization tax regimes as regulated by the Petroleum Profit Tax Act (PPTA). Economic yardsticks such as NPV, IRR, PI and PVR were used to rank proposed investments. Results from the deterministic evaluation were presented for offshore and land-based LNG facilities as a base case. These results were extended to evaluate the economic risks associated with uncertainties in feedstock costs, LNG prices, plant capacities, CAPEX and OPEX. Although all proposed investments ensure good profitability with respect to the deterministic approach, nonetheless risk assessment ranked the offshore LNG facility under PSC as the most preferable project. However, Nigeria's gas reserve and flaring practice purports a complementary application of both LNG configurations.
Optimising Reservoir Production in WRFM by Unleashing Locked-in Potential through Trusted Data at Finger's Tip
Authors: Sunday Ewhoforama , Nkonyeasua Oghene , Olumide Ayeni , Gbolade Ibikunle , Tamunotonye William , Efe Ori-Jesu
Published: July 2016

The benefits of credible data and data quality came to bear recently with the restoration of reservoir production in an SPDC field. The reference string produced dry at an average rate of 1500 bopd and Gas Oil Ratio (GOR) of 2000scf/bbl till June 2000 when water breakthrough occurred. GOR increased sharply by 2011 and the interval was closed-in in 2012 at GOR of 8Rsi (Rsi-initial solution gas oil ratio).

A previous integrated review proposed water shut-off (WSO) as well as gas shut-off (GSO) to be executed so that this interval can be brought back on stream. In September 2015, an integrated review of Closed-in Wells was done in which all available data pertinent to this well was analysed and reviewed. Based on this comprehensive data, the review team arrived at a conclusion to open up and test the well rather than WSO/GSO proposed in the previous review. In making this decision, the team was convinced it had access to credible and reliable data set. This is enabled with the creation of The Asset Standard Well Reservoir and Facility Management (WRFM) Technical Data Management Plan (TDM) that clearly states data repositories, data owners and focal points. These data sets were easily retrieved from the various data repositories.

The Asset Standard Well Reservoir and Facility Management (WRFM) Technical Data Management Plan (TDM) clearly states data repositories, data owners and focal points. The string was opened on October 25, 2015 and it was observed to be stable and flowing at 435 bopd, in line with the review forecast. Well testing of October 29, 2015 validated the production rate at 462bopd, 700scf/bbl (1.6*Rsi) at 27% BSW.

The availability of credible and trusted data has therefore helped in optimising production of this well. There is also a cost saving typical of a water shut-off activity. Credible data that are easily accessible can make a difference on the business bottom line especially in optimising production, managing integrity and emergency repairs of an asset. These were demonstrated in the closed-in well review that has led to increased production and cost savings – the benefits of credible data.
Enhanced Geosteering With While-Drilling Productivity Evaluation: A Methodology to Optimize Horizontal Well Productivity
Authors: Okoroafor Rita Esuru , Ekhaesomhi Peter , Ipinyemi Gbemiga , Oyenuga Funso , Ilesanmi Olumide , Haq Shahid , Zhou Wentao , Ortenzi Luca , Nnebocha Ezinne
Published: July 2016

Geosteering is a proven concept which enables the delivery of productive wells by ensuring such wells stay within the target reservoir and sweet spot, and are precisely placed relative to fluid contacts. When reservoir engineering concepts are combined with Geosteering, quantitative estimates of the well's productivity can be determined to further evaluate the performance of the Geosteering and aid in decision-making. This workflow, applied in real-time, is called Real-Time Productivity Steering (RTPS).

This paper describes the application of RTPS to a horizontal well placed in a thin layer of oil reservoir. Prior to performing the real time productivity estimates while drilling, a prejob model was built, using offset well data, to estimate productivity from the planned well. Sensitivity analysis was performed on the trajectory, well length and some rock and fluid properties, to determine the plan that would result in optimum productivity for the well.

While the well was drilled, Logging While Drilling (LWD) information was used to update the existing model, geosteer, and perform productivity prediction while drilling. Productivity was predicted at three target depths: 8400 ft MD, 8800 ft MD, and at Total Depth (TD). The increasing liquid productivity index (PI) at the selected target depths were further justification to continue drilling until the predetermined TD.

The results at TD showed that the open hole liquid PI of the well in the sand of interest was about 63.8 stb/d/psi for a stable production rate of 1200 blpd. When completions were imposed on this single well reservoir model, it was predicted that the well will produce at a stable rate of 750 bopd. This was compared with a preliminary test done on the well where for the same well and reservoir conditions, the well produced 800 bopd.

This paper demonstrates that quantitative estimates of productivity can be made while drilling to complement geosteering. In addition to complementing and enhancing geosteering, RTPS provides a reliable dynamic model for subsequent completion design.

The RTPS workflow of complementing geosteering with reservoir engineering will enhance the ability to drill more productive wells as it will enable wells to be steered in the direction of maximum productivity, and also provide operators with sufficient information while drilling to make informed decisions for completions and for future wells.
Dimensionless Inflow Performance Relationship IPR for Gas Wells Using the Back Pressure Equation
Authors: Akineste Oluwatoyin O. , Olujinmi Temitope O.
Published: July 2016

Dimensionless inflow performance relationship (IPR) has been developed for unfractured gas reservoirs using the laminar inertial turbulence (LIT) relation with various assumptions. This is evident from papers earlier presented where predictions from the LIT correlation closely match field data. Development with the backpressure empirical relation has had little progress. An assumption of n=1 for the backpressure relation over predicts gas flow rate by approximately 19% for an Alberta field.

This paper presents the development of dimensionless IPR correlations which predicts current and future deliverability of an unfractured gas reservoir using the backpressure empirical relation. The developed dimensionless IPRs accounts for turbulence by accounting for the range of turbulence factor (n) between 0.5 – 1. Developed using Microsoft Excel with several data points to account for varying reservoir properties. The best fit curves were determined, and the equations relating qgqgmax to pwfqr and that relating qgmaxfqgmaxp to prfprp for present and future deliverability respectively are expressed.

The developed dimensionless IPR correlations were tested for accuracy and validity by comparing with results from isochronal and modified isochronal tests. The IPRs shows consistency with field data, and therefore can be used in the calculation of the deliverability potential of a gas reservoir.
Artificial Neural Network Model for Predicting Wellbore Instability
Authors: Okpo E. E. , Dosunmu A. , Odagme B. S.
Published: July 2016

Drilling activities have progressed to deep and ultra deep seas in recent times and with it comes more challenges. Due to the difficulty of directly obtaining important parameters like in-situ stress and fracture gradient, simple models have been evolved. This study is a novel attempt to make up for the gap inherent in such models namely that they neglect chemical and thermal effects, settling for only effective stress and a time-dependent analysis. The study applied the Neural Network (NN) technology to predict geomechanical parameters. Neural Network (NN) as a branch of Artificial intelligence (AI) possesses the ability of training available parameters to replace data that cannot be immediately or easily acquired. Data of a well drilled in the Niger Delta Region of Nigeria was used as the case study. A training set of input data was used to train the network and a validation set ensured a completely independent measure of network accuracy. A Neural Network model was developed in Neuroph Studio, Java neural network platform and the Netbeans IDE. The model has the advantage of being easy to use, open source, cross-platform and generally designed to save the cost associated with wellbore instability.
Reducing Unit Technical Cost Through Improved Crude Handling Contract Management
Authors: Arabi Abubakar Bello
Published: July 2016

Profitability remains the key driver for investment in the oil & gas business. Profit margins are enhanced through cost minimisation or revenue maximization, and in some instances, companies deploy tools to guarantee the combination of both to deliver increased corporate profit.

Given the relative challenges associated with ability of players in the industry to grow production capacity and increase market share/revenue, cost minimisation becomes the tool deployed most often to achieve increased profitability. As the global oil prices continue to plummet, focus on cost reduction/saving as a tool for profitability has gained renewed attention from industry players. Thus, technical cost or unit technical cost remains a critical KPI for measuring operational efficiency/profitability in the E&P business.

Crude handling cost, which covers the cost of crude transportation and terminaling, constitute significant chunk of operating cost for most E&P companies in Nigeria. With an average contractual price of $3.5 per barrel of wet crude and $2.81 per barrel of dry crude, driving down this cost element underpins a significant cost saving for any E&P company. Alas, actual handling cost per barrel is always higher than the contractual rate per barrel. The magnitude of variance depends on the operational efficiency of the company and how best it has been able to manage Reserved Production Capacity (RPC) vis-à-vis the ability to perform the work programme upon which its production forecast that informed the choice of RPC was premised.

In this article we seek to demonstrate how NPDC was able to reduce unit technical cost through the combination of deployment of optimal RPC selection model and increased vigilance/effective CHA Management. In addition, we intend to also demonstrate how related actions such as increased-RPC-Review-Window (IRRW) could poster greater collaboration between facility-users and facility-owners and help achieve reduce crude handling tariff rates in a fairly win-win scenario.
Improved Correlation for Predicting Stock Tank Gas-Oil Ratio in Niger Delta
Authors: Okeke Hillary , Sylvester Okotie
Published: July 2016

The estimation of the stock tank gas-oil ratio (GOR) cannot be over-emphasized because it is a vital surface parameter required in the estimation of cumulative gas-oil ratio, the stock tank production rate and bubble point solution gas-oil ratio. Ideally, this property is determined via laboratory measurement which is not done regularly due to cost and sampling time. The three popular correlations developed for predicting this property were found to be less applicable in Niger Delta region. This challenge now led to the development of a new correlation by the author of this paper using Niger Delta data which is more applicable than the existing ones but still associated with appreciable error in its prediction. In this study, an improved stock tank GOR correlation for Niger Delta crudes is presented so as to reduce error of prediction. Unlike the former correlation, it is a non-linear four parameter mathematical model that depends on stock tank oil API gravity, separator pressure, separator temperature and separator gas gravity. A total of 222 PVT reports were obtained and validated using material balance, Campbell and Hoffman's Plots. Microsoft excel solver was used to generate the improved model for stock tank gas-oil ratio. The model was then validated with existing correlations including the one from Niger Delta region using statistical analysis and performance plots. The results of the validation showed an improvement in the accuracy of the prediction.
Artificial Neural Network Modelling of Bubblepoint Pressure and Formation Volume Factor at Bubblepoint Pressure of Nigerian Crude Oil
Authors: Adeeyo Yisa A.
Published: July 2016

Reservoir fluid properties data are indispensable in reservoir engineering evaluations and computations. Ideally, those data should be obtained experimentally. On some occasions, these data are either not available or grossly unreliable; then, empirically derived correlations are used to predict PVT properties. Most correlations in the literature were either modelled using regional data or their level of accuracy is low.

Artificial neural network is a new computation strategy that could be used to generate model for predicting PVT properties. It consists of simple arrangement of nodes, called neurons, used for pattern recognition, modeled after a representation of human brain.

The author has explored the use of neural network in estimating bubblepoint pressure and formation volume factor at bubblepoint pressure with the aim of getting more accurate prediction compared to available correlations in the literature.

The number of data set used for bubblepoint pressure is 2114 and oil FVF at bubblepoint is 2024. Various neural network designs with one-hidden, two-hidden and three-hidden layers were considered and tested. The number of neurons in the hidden layer was varied until stable network was achieved. Each successful trained model was tested to ensure that overfitting does not occur and can predict output from inputs that were not seen by the model during training. Sixty percent of the data was used to train the network, twenty percent to cross-validate the relationships established during the training process and the remaining twenty percent to test the model.

The results of this study show that the model gives better prediction and higher accuracy compared to the published bubblepoint pressure and formation volume factor empirical correlations.
Gibbs Excess Energy Model to Predict Phase Behaviour of Brine/Oil/Surfactant Mixtures for Chemical Enhanced Oil Recovery CEOR Methods
Authors: Adeeyo Yisa A. , Awang Mariyamni bint
Published: July 2016

With the increase in the world population, increases in scientific and industrial activities have engendered spontaneous upsurge in the global demand for oil and gas in the past few years. These resulted in depletion of major world oil reservoir without corresponding discovery of new major oil fields.

However, substantial amount of oil is trapped inside the reservoir. This oil is being held by capillary force which depends on interfacial tension (IFT) between oil and water. Therefore, reducing the IFT releases the oil and enables greater recovery.

Surfactant (surface acting agent) reduces IFT and has been tested to be appropriate for use under reservoir condition. A mixture of surfactant, brine and oil may produce microemulsion depending on the proportion of the amount of the components and thermodynamic parameters involved. Microemulsion reduces IFT. The practice in the industry is to conduct laboratory experiments to investigate various formulations and identify the thermodynamic conditions that will yield microemulsion phase.

This study is aimed at developing mathematical thermodynamic model and computation algorithm using excess Gibbs energy, fugacity and group contribution model (GCM) for the estimation of critical properties of the pseudo-components to predict phase behavior of water/oil surfactant mixture in the regions and beyond those their measurements have been conducted in the lab.

The model was validated by comparing its performance to lab results. The lab experiments involved measuring the phase behaviour of the mixture of Alfa Olefin Sulfonate (AOS) surfactant, decane and brine.

The model shows good performance and will be useful in the prediction of phase behavior of water/oil surfactant and can be used in compositional simulation of surfactant flooding operations and should be an invaluable tool in planning and evaluation of surfactant flooding processes.
Forecasting Gas Compressibility Factor Using Artificial Neural Network Tool for Niger-Delta Gas Reservoir
Authors: Irene Azubuike Ijeoma , Sunday Ikiensikimama Sunday , Orodu Oyinkepreye David
Published: July 2016

Accurate prediction of gas compressibility factor is important in engineering applications such as gas metering, pipeline design, reserves estimation, gas flow rate, and material balance calculations. This factor also is important in calculating gas properties such as gas formation volume factor, gas isothermal compressibility, viscosity and density. Compressibility factor value shows how much the real gas deviates from the ideal gas at a given pressure and temperature. Most often, compressibility factor values can be determined experimentally from collected laboratory samples but frequently this measurement is not always available. In such cases, the natural gas property can be determined using empirical correlations or iteratively using equation of state (EOS). Therefore, the aim of this work is to develop ANN model to accurately predict the gas compressibility factor; as well to compare its performance with existing empirical gas compressibility factor correlations. The new model was developed using 513 PVT data points obtained from Niger-Delta region of Nigeria. The data used wasrandomly divided into three parts, of which 60% was used for training, 20% for validation, and 20% for testing. Both quantitative and qualitative assessments were employed to evaluate the accuracy of the new model to the existing empirical correlations. The ANN model performed better than the existing empirical correlations by the statistical parameters used having the lowest rank of 1.37 and better performance plot.
Understanding the Geometry and Structural Controls of Fluid Levels in Relay Systems, Nigeria
Authors: Mora-Glukstad Miguel , Ugboaja Remmy
Published: July 2016

A review of many oil/gas fields in Nigeria shows that most structures are under-filled (the fluid contact is much shallower than the structural spill point). This could be explained in different ways. Hydrocarbon charge has been suggested as a possible explanation, but we do not believe this to be the main cause in such a rich hydrocarbon province, like the delta, and where there are excellent carrier beds and world class source rocks, all throughout the system.

Another possible cause could be what we call a "dynamic top seal," where there is some degree of leakage either due to capillary forces or facilitated by crestal faulting. An ongoing analysis on capillary entry pressure and mechanical strength of the top seal, shows that this could be the case in some shallow reservoirs, but a "leaky" top seal does not appear to be a major issue in relatively deeper reservoirs.

An updated seismic interpretation was carried out in field X where part of the focus was to understand what controls the current fluid contacts. This study has direct implications towards predicting fluid contacts in near field opportunities in undrilled blocks for proper placement of development wells. Field X has one single well but there are undrilled blocks with similar structural geometries. These learnings will also help to carry out predictions of in place volumes for near field development.

This work showed that more careful and detailed structural mapping of the fault systems provides a view of fault geometry where relay ramps clearly control the position of the fluid level. The position of the initially planned well changed. We are applying these learnings and testing if this observation can be replicated in other fields, once more detailed mapping is carried out.
Prediction of inventory sustainability during a drug shortage
Authors: Rhodes Nathaniel J. , Gilbert Elise M. , Skoglund Erik , Esterly John S. , Postelnick Michael J. , McLaughlin Milena M.
Published: July 2016

Purpose

A methodology for predicting how long the on-hand inventory of a given medication will last during a supply shortage is described; a practical example of application of the methodology is provided.

Methods

Single-site data on consumption of i.v. tobramycin over an eight-month evaluation period were collected using commercial software that tabulates barcode-assisted medication administration (BCMA) events; administered doses were standardized as 1200-mg “vial-equivalents” and summed over the review period. The total number of vial-equivalents consumed was divided by the number of “non-zero weeks of consumption” (i.e., weeks during which any tobramycin use occurred) to obtain a mean ± S.D. weekly consumption rate; this rate was multiplied by the total i.v. tobramycin on-hand supply (in vial-equivalents) to determine the mean number of potentially sustainable weeks of therapy in the event a shortage were to restrict the future supply of the drug.

Results

Overall, 99.6 vial-equivalents of i.v. tobramycin were used during the evaluation period. The mean ± S.D. number of vial-equivalents used per non-zero week of consumption was 3.11 ± 1.26. A manual count of pharmacy inventory revealed that 102.9 vial-equivalents were available at the time of analysis. The mean predicted duration of supply was 33 weeks (95% confidence interval, –126 to 192 weeks).

Conclusion

Available BCMA data on tobramycin consumption over eight months were used to calculate the mean number of weeks the on-hand supply of the drug could be expected to last during a persistent drug shortage.
Olaparib for the treatment of BRCA-mutated advanced ovarian cancer
Authors: Munroe Marklie , Kolesar Jill
Published: July 2016

Purpose

The pharmacology, clinical efficacy, safety, dosage and administration, and role in therapy of olaparib, a first-in-class treatment for advanced treatment-refractory ovarian cancer, are reviewed.

Olaparib (Lynparza, AstraZeneca) is an oral inhibitor of poly(ADP-ribose) polymerase (PARP) proteins that play a key role in DNA repair and genomic stability. Olaparib is indicated for use in treating certain patients with advanced, recurrent ovarian cancer who have mutations of the breast cancer 1 gene (BRCA1) or breast cancer 2 gene (BRCA2). In patients with BRCA-mutated cancers, olaparib blocks vital PARP-mediated tumor cell DNA repair mechanisms, leading to “synthetic lethality” and selective tumor cell death. In Phase II clinical trials including patients with platinum-sensitive, platinum-resistant, and platinum-refractory ovarian cancers, olaparib significantly improved progression-free survival, with similar rates of response reported in patients with BRCA1- and BRCA2-mutated disease. Olaparib is generally well tolerated; the most commonly reported adverse events in clinical trials were mild nausea, fatigue, vomiting, and diarrhea. Severe anemia and severe fatigue can occur in association with olaparib treatment. Concurrent administration of olaparib and strong or moderate inducers or inhibitors of cytochrome P-450 isozyme 3A should be avoided, as use of those agents may alter plasma concentrations of olaparib.

Conclusion

Olaparib is a novel PARP inhibitor that is efficacious and well tolerated in patients with BRCA-mutated advanced ovarian cancers who have received three or more lines of prior treatment.
El Desequilibrio de lo Político en Hegel
Authors: Krause Juan Ignacio Arias , Mardones Patricio Landaeta
Published: July 2016

El problema político de la sociedad civil se fundamenta en su doble forma de manifestarse: por un lado, en ella se revela el carácter externo u objetivo del Estado y, por otro, produce una escisión al interior del mismo Estado. Tal problema que aparece como contradictorio (el ser exterior e interior a la vez) es presentado en el pensamiento político de Hegel, en vistas a superar las dicotomías que en la teoría política moderna aparecían como insalvables. Esta superación Hegel la realiza mediante una interiorización de aquellos elementos que anteriormente habían sido marginados de la política, como son lo natural y el dominio privado, los que emergerían en la sociedad civil. En este artículo se exponen estos elementos en vistas a mostrar cómo es en este movimiento de interiorización y exteriorización de ellos donde se posibilita el acontecer de lo político.
Impact of multiple wastewater feedings on the efficiency of nutrient removal in an IFAS-MBSBBR: number of feedings vs. efficiency of nutrient removal
Authors: Podedworna J. , Zubrowska-Sudol M. , Sytek-Szmeichel K. , Gnida A. , Surmacz-Górska J. , Marciocha D.
Published: July 2016

This article presents the results of research into the influence of one, two and three wastewater feedings in a cycle on efficiency and performance of combined biological nitrogen and phosphorus removal in an integrated fixed-film activated sludge and moving-bed sequencing batch biofilm reactor (IFAS-MBSBBR). The experiment lasted 158 days and was conducted in two laboratory models of the IFAS-MBSBBR with an active volume of 28 L. It was found that along with an increase in the number of wastewater feedings, an increase in nitrogen removal efficiency was observed (from 56.9 ± 2.30% for a single feeding to 91.4 ± 1.77% for three feedings). Moreover, the contribution of simultaneous nitrification/denitrification in nitrogen removal increased (from 2.58% for a single feeding to 69.5% for three feedings). Systems with a greater number of feedings stimulated the process of denitrifying phosphorus removal. Regardless of the way in which wastewater feeding was applied to the IFAS-MBSBBR, highly efficient chemical oxygen demand (COD) removal (94.8 ± 1.80%) and biological phosphorus removal (98.9 ± 0.87%) were achieved.
Can there be an immoral morality? Dark personality traits as predictors of moral foundations
Authors: Medjedovic Janko , Petrovic Boban
Published: July 2016

Previous researches have shown that some aspects of Moral foundations do not
correlate with indicators of immoral behavior, or even have positive
correlations with them. The aim of this study was to explore the relations of
Moral foundations with general (HEXACO personality model) and ?dark?
personality traits (psychopathy, Machiavellianism, narcissism and sadism).
Data was gathered via on-line survey (N=402; 70% females). The results have
shown that Openness is the best predictor from the set of basic personality
traits: It has positive relations with Harm/Care and Fairness/Reciprocity and
negative with the other three moral foundations. Psychopathy was negatively
associated with Harm/Care and positively with Ingroup/Loyalty foundation.
Machiavellianism was a positive predictor of Ingroup/Loyalty and Authority/
Respect. Results confirmed the existence of fundamental differences between
moral foundations. Ingroup/Loyalty and Authority/Respect are partly based on
immoral personal dispositions, which bring into question their conceptual
status as human moral foundations.
Evaluation of the hexagonal and spherical model of vocational interests in the young people in Serbia and Bulgaria
Authors: Hedrih Vladimir , Stosic Marina , Simic Ivana , Ilieva Snezana
Published: July 2016

The aim of this study was to validate Holland?s hexagonal and Tracey?s
spherical model of vocational interests in young adults in Serbia and
Bulgaria. To this end, 1250 participants, 560 from Serbia and 690 from
Bulgaria, filled in Serbian and Bulgarian versions of the Personal Globe
Inventory (PGI, Tracey, 2002). Hubert and Arabie?s randomization test of
hypothetical orders, multidimensional scaling with fixed coordinates, Myors
test and exploratory factor analysis were used. The results showed that the
hexagonal and spherical models well explained the structure of vocational
interests in both samples. The level of fit of the hexagonal model to the
data obtained by using the PGI was generally higher than those established in
the studies that used other Holland-based instruments. Furthermore, the
levels of fit of both hexagonal and spherical model were in the same range
like those obtained in previous studies in other countries. The results also
pointed out a remarkable similarity in the structure of vocational interests
in the Bulgarian and Serbian samples.
The Na+/Glucose Cotransporter Inhibitor Canagliflozin Activates AMPK by Inhibiting Mitochondrial Function and Increasing Cellular AMP Levels
Authors: Hawley Simon A. , Ford Rebecca J. , Smith Brennan K. , Gowans Graeme J. , Mancini Sarah J. , Pitt Ryan D. , Day Emily A. , Salt Ian P. , Steinberg Gregory R. , Hardie D. Grahame
Published: July 2016

Canagliflozin, dapagliflozin, and empagliflozin, all recently approved for treatment of type 2 diabetes, were derived from the natural product phlorizin. They reduce hyperglycemia by inhibiting glucose reuptake by sodium/glucose cotransporter (SGLT) 2 in the kidney, without affecting intestinal glucose uptake by SGLT1. We now report that canagliflozin also activates AMPK, an effect also seen with phloretin (the aglycone breakdown product of phlorizin), but not to any significant extent with dapagliflozin, empagliflozin, or phlorizin. AMPK activation occurred at canagliflozin concentrations measured in human plasma in clinical trials and was caused by inhibition of Complex I of the respiratory chain, leading to increases in cellular AMP or ADP. Although canagliflozin also inhibited cellular glucose uptake independently of SGLT2, this did not account for AMPK activation. Canagliflozin also inhibited lipid synthesis, an effect that was absent in AMPK knockout cells and that required phosphorylation of acetyl-CoA carboxylase (ACC) 1 and/or ACC2 at the AMPK sites. Oral administration of canagliflozin activated AMPK in mouse liver, although not in muscle, adipose tissue, or spleen. Because phosphorylation of ACC by AMPK is known to lower liver lipid content, these data suggest a potential additional benefit of canagliflozin therapy compared with other SGLT2 inhibitors.
Physical fitness of people with moderate and considerable intellectual disabilities
Authors: Ślężyńska Marzena , Mięsok Grzegorz , Mięsok Kamila
Published: July 2016

Introduction: The aim of the physical activity of the intellectually disabled is the strengthening of health, creating movement habits, promoting active recreation, and maintaining exercise capacity. Skillfully applied physical activity allows to mitigate the effects of pathology and create the compensations to enable the intellectually disabled people to live relatively independently. Physical activity and sport also increase their chances to integrate with their families, peers, and social environment.

Materials and methods: The research targeted a group of 134 people with moderate or considerable intellectual disability (65 women and 69 men), aged 20-53 years, who participated in occupational therapy workshops in Jastrzębie Zdrój, Rybnik, and Żory. Physical fitness was assessed using the “Eurofit Special” test and balance tests. Measurements of body height and mass were also taken and then used to calculate the body mass index (BMI).

Results: A salient somatic trait was the greater body mass relative to height among the persons with considerable disability, clearly illustrated by the BMI. This explained their greater heaviness in performing physical exercises. An even greater difference between participants with moderate and considerable intellectual disability was visible in physical fitness. Obviously, older persons did not achieve as good results in fitness tests as the younger ones, yet the participants were more differentiated by the level of disability than age. Most symptomatic differences to the disadvantage of the considerably disabled were observed in explosive strength, speed, abdominal muscle strength, and flexibility.

Conclusions: Significant differences in fitness between the compared groups make it necessary to take into account the level of intellectual disability in the course of physical education and sport, at work, and in household duties.
Changes in selected functional parameters in patients after hip arthroplasty – preliminary report
Authors: Hawrylak Arletta , Barczyk Katarzyna , Demidaś Aneta , Wojna Dorota , Anwajler Joanna , Matczak Małgorzata
Published: July 2016

The aim of this study was to assess the effect of physical therapy procedure on a series of selected functional parameters in patients after hip arthroplasty. The study was carried out on a group of 25 patients aged 65-75 years during their stay at the “Niebieski Parasol” Nursing and Rehabilitation Centre in Chojnow. The patients underwent a clinical test on the 10th day after surgical intervention. A goniometer was used to measure the hip joint range of motion. In order to measure functional balance with the Berg Balance Scale the following tools were used: a stopwatch, a centimetre tape, a chair and a step. The test was performed twice, before physical therapy and after 6 weeks. The application of the physical therapy procedures in the experimental group contributed to an increase in the hip joint range of motion in all the mobility ranges assessed in the study and led to an improvement in the hip joint balance and gait assessed with the Berg Balance Scale.