bluuebunny/crossref_metadata_2025 huggingface dataset:
Production Optimization through Pressure Transient Analysis
Authors: Olufisayo Fagbowore , Anthony Oyewole
Published: July 2019

Intelligent field completions have seen more frequent deployment in the oil and gas industry in recent times. This is most likely due to the benefits that have been observed from real-time data acquisition, surveillance and optimization based on analysis of data gathered. With continuous acquisition of real-time data, analysis of the transient pressure and rate data can be used to understand changes in reservoir and well performance over time. The aim of this paper is to show how the evolution of parameters obtained from pressure transient analysis can be used to optimize well and reservoir performance.

Key parameters obtained from pressure transient analysis (PTA) are permeability, skin, reservoir pressure and information on boundaries depending on shut-in duration. Analyses are performed for all shut-ins of the completion, both planned shut-ins and unplanned shut-ins (emergency shutdowns - ESDs). The results of all these analyses are catalogued to provide an historical surveillance data which, when trended, can provide insight into the near-wellbore performance of a completion as well as the reservoir.

This paper demonstrates how Pressure Transient Analysis of real-time data was used in the Agbami Field to optimize production from the field. Two case studies are presented where analysis of transient pressure data was used to identify water injection front movement in a waterflooded reservoir and increasing near-wellbore damage due to fines migration. The results were used to optimize injection into a waterflooded reservoir to achieve a balance between maintaining reservoir pressure and optimizing voidage. In the case of continually increasing skin, the completion was stimulated with production increasing by a factor of 15.
Characterization of Potential Paraffin Wax Removing Bacteria for Sustainable Biotechnological Application
Authors: Okoye A. U. , Chikere C. B. , Okpokwasili G. C.
Published: July 2019

The presence of paraffin wax precipitation and deposition in tubing surfaces during production is one of the all-encompassing nuisances in oil and gas industry operations worldwide and it causes major production problems. The study aimed at acquiring novel insights into the bacterial community diversity capable of utilizing paraffin wax. Samples were collected from crude oil-polluted site in Gio Community, Tai Local Government Area, Niger Delta, Nigeria at depth of 0-0.5m (surface polluted soil [SPS]), 1m (sub surface polluted soil [SPSS]). GPS coordinate points for the North, South, East and West were N40 41′ 39″; N40 41′ 38″; N40 41′ 38″ and N40 41′ 37″ for latitudes respectively. Longitudes for the coordinates were E70 13′ 49″; E70 13′54″; E70 13′ 53″ and E70 13′ 54″ for North, respectively and unpolluted soil (UPS) taken 80m away from polluted site as control. All samples were transported to the laboratory within 6h at 4°C for analyses. Biodegradation screening was carried out using 2, 6-dichlorophenol indophenol (DCPIP) (redox potential +0.217 V) indicator to evaluate the biodegradation of hexadecane, paraffin oil and crude oil by axenic cultures of the bacteria isolated. GC-FID analysis for total petroleum hydrocarbons (TPH) were 22,146.65ppm for (surface polluted soil [SPS]), 14,087.80ppm (sub surface [SPSS]) and control soil (UPS) 479.67ppm respectively. Polycyclic aromatic hydrocarbons (PAHs) were 12,209.3ppm for SPS, 3,248.75ppm for SPSS and 22.72ppm for UPS. Total cultivable hydrocarbon utilizing bacterial count (TCHUB) for SPS, SPSS and UPS were 8.4 × 105cfu/g, 8.0 × 105cfu/g and 3.96 × 104cfu/g respectively. Pseudomonas spp., Bacillus spp., Acinetobacter sp. and Serratia sp. demonstrated higher biodegradability of paraffin wax than other 62 TCHUB isolated. These bacteria may probably represent an alternative green method for scale removal in the oil and gas sector.
Achieving & Sustaining Impeccable HSE Performance in Brown Field Operations Comes at a Cost OML26 Blazes the Trail
Authors: Acha Smart , Fadairo James , Ogiesoba Dennis , Okeke Ikenna , Emmanuel Tata , Brown Joseph A.
Published: July 2019

The Nigerian Petroleum Development Company Limited (NPDC), and First Hydrocarbon Nigeria (FHN) its joint venture partner in Oil Mining Lease (OML) 26, established OML 26 Asset Management Team (AMT) to manage the lease together with all the assets and facilities on behalf of the joint venture (JV). The facilities include the flow station, the compressor station, and the gantry at Ogini field, a LACT Unit at Eriemu, and Operational Base for alternative evacuation in Asaba – Ase all in Delta State, Nigeria.

Since the inception of the AMT in 2016, the asset has achieved and maintained a GOAL ZERO HSE performance record. Achieving GOAL ZERO HSE performance in a brown field like OML 26 is a herculean task. It is so, considering the operational challenges that require aggressive interventions in the forms of various projects, and the increased field activities. The debottlenecking activities results in more manhours, greater exposures and a high propensity for environmental impact. In line with the vision of the AMT to be the Best Performing Energy Investment (BPEI) the HSE department established a proactive system for identifying and managing operational risks and ensuring regulatory compliance consistently.

This paper highlights the tremendous efforts, strategies and policies of the HSE department in ensuring success and meeting set HSE goals. It focuses on the costs in terms of commitments, governance and drive at all levels in achieving a sustained impressive performance and compliance to regulatory and international standards.
Pressure Relief Management Philosophy for MPD Operations on Surface Stack HPHT Exploration Wells
Authors: Benyeogor Ogochukwu , Jambol Donald , Amah Obinna , Obiga David , Awe Sunday , Erinle Adeyemi
Published: July 2019

Managed pressure drilling (MPD) is an adaptive drilling technique used to improve the economics and to mitigate risks associated with drilling high pressure and high temperature (HPHT) exploration wells where the drilling window is often narrow. The technique involves the combination of surface back pressure and fluid hydrostatic column to provide the required bottom hole pressure for safe drilling. Typical MPD equipment spread includes rotating control device (RCD), chokes, high pressure lines and gate valves with Pressure relief valves (PRVs) incorporated. The primary purpose of the PRV is to protect the MPD surface equipment and the formation from being overpressured. The relief valve achieves this by bypassing the normal fluid flow path for MPD operations and relieving the system pressure to the rig Mud gas separator (MGS) through a dedicated line. Each time a PRV is activated the resulting loss of surface back pressure increases the risk of taking a kick. On the other hand, when a PRV is not activated, an excessive increase in surface pressure raises the risk of formation fracture leading to losses. Therefore, the performance of the PRV has an immense impact on assessing the risk of a well control situation, which may be caused by either loses due to formation breakdown and consequently a kick from loss of the hydrostatic pressure component of the equivalent surface density (ESD) or an influx as a result of loss of surface back pressure component of the ESD due to loss of integrity of surface equipment).

Pressure Relief Management philosophy generally covers decisions such as which parts of the well system (surface and subsurface) are to be preferentially protected by the PRVs, selection of activation pressure for high level alarms, types, number and setpoints of PRVs in the MPD system during different phases of the drilling operations - drilling, connections and tripping, and MPD choke full-opening pressure. These values are dependent on formation integrity test (FIT), mud weight, drilling window, annular friction pressure and operating envelope of RCD. The set points require adjustment depending on the hole size and flow rate and may be different during completion and well control operations.

This paper describes the Pressure Relief Management philosophy for a HPHT well drilled in the Niger delta. It looks at factors that drive the high-pressure alarm setting values, choice of PRV types, placement and the part of the well system being protected, PRV tripping and reset values, and MPD choke full opening pressures. It also describes the challenges and risk assessment that influenced the selection of set points (single or dual setpoints) for different phases of the drilling operations.
Evaluating the Performance of Local Anionic Emulsifier as a Possible Emulsifier for Synthetic-Based Mud System for Drilling Operations
Authors: Amorin Richard , Broni-Bediako Eric , Adanvor Joel Bright , Appau Prince Opoku
Published: July 2019

In the process of formulating oil-based muds, emulsifiers or surfactants are added to help build a strong oil-water emulsion. Currently, all the emulsifiers used in mud formulation in Ghana are imported increasing drilling cost. This also do not promote the local content and local participation policy of the country in the oil and gas sector. There are equally potential local emulsifiers that could be used in these mud formulations to reduce cost. This research, therefore, evaluated the performance of local anionic surfactant as a possible emulsifier for an ester-based oil mud system for drilling operations. A Synthetic-Based Mud (SBM) was formulated with varying concentrations of both local (L) and commercial (C) emulsifiers from 0% to 100% at a step of 25% after which their rheological properties evaluated. The rheological properties were evaluated for unaged samples at temperatures of 80 °F, 120 °F, 180 °F and aged samples at a temperature at 180 °F. The performances of the mud samples were tested using Gel Strength at 10 seconds and 10 minutes, Plastic Viscosity, Yield Point and pH at each varied concentration of emulsifier following closely the American Petroleum Institute (API) standard test procedures. The overall performances of the mud samples in order of descending were; BL100% > AC100% > EC25%L75% > CC50%L50% > DC75%L25%. It was observed that the local emulsifier performed equally well and even better than the commercial emulsifiers at the test conditions presenting the local emulsifier as a potential emulsifier for the formulation of SBMs for the oil and gas industry.
Evaluation of Rock Failure Models for The Determination of a Safe Mud Weight Window During Drilling Operations in The Niger Delta
Authors: Success Chioma Ogbechie
Published: July 2019

Unstable boreholes due to tensile & shear failure results in serious drilling problems. This increases the non-productive time spent in the field and the cost of reviving failed wells in the oil and gas industry in order to mitigate or prevent borehole failure, different rock strength criteria models have been developed to predict the optimum required mud weight but unfortunately, not all models fit for all formation considering the different drilling conditions, hence these models need to be evaluated to check their validity and accuracy for drilling stable wells in the Niger Delta. To achieve this purpose, collapse and fracture pressure that defines the lower and upper boundary of a mud weight window are calculated using derived formula equations from three failure criteria models; Hoek-Brown failure criterion, Mohr-Coulomb failure criterion and Mogi-Coulomb criterion failure criterion. This is achieved using Microsoft Excel and the simulation is done on a plot to show the different mud window by each model for comparison. The input parameters relevant for this study are pore pressure, in-situ stress data and rock mechanical properties which were acquired from a high-pressured zone in an xxx-onshore oilfield of the Niger Delta. A plot of the predicted optimum mud weight vs the actual mud weight against depth is compared to check the accuracy of each model to conclude on the failure criterion that is best fit for the formation in this field. The results showed that Hoek-Brown failure criterion gave an unrealistic outcome, when used to drill will lead to borehole breakout. Mohr-Coulomb and 3D Mogi-Coulomb criteria gave similar results which can be used but Mogi-Coulomb is recommended for drilling stabilized vertical wells due to the consideration of intermediate principal stress effect on rock strength over the conservative Mohr-Coulomb.
Demonstrating the Value of Early Incorporation of Dynamic Data during Probabilistic Assessment for a Niger Delta Gas Condensate Reservoir
Authors: Ogbuagu Frank , Silpngarmlers Lynn
Published: July 2019

The paper aims to highlight the importance of using adequate dynamic data to ground-truth reservoir simulation models early in the production life of a field. This study also highlights the benefits of adequate instrumentation and data capture, as well as the need to review assumptions made for green fields in their first few production years.

This study reviews two vintages of probabilistic assessment for an offshore gas condensate reservoir. An earlier probabilistic assessment for the case study reservoir was built based primarily on core data from two analogous reservoirs, one of which was from the same field, prior to the availability of bottom hole pressure and drawdown data. Initial history match and forecasts showed a significantly poor production performance with significant impact on the condensate reserves volumes from the single well in the reservoir.

Following the acquisition of pressure data from the downhole gauges and pressure transient analyses results, the model recalibrated in line with estimated distance to boundaries, drawdown and productivity indices. Incorporating the additional data from the downhole instrumentation during the history match showed the earth model severely underestimated the permeability of the reservoir. Matching the drawdown and well test data required a significant permeability multiplier for the low and mid case models for the reservoir.

A comparison of results from both model vintages showed significant differences in the expected production plateau for the reservoir and consequently reserves estimates. These finding demonstrates value of the acquisition of multiple downhole dynamic data and the pitfalls with reservoir performance forecasts and reserves assessments when simulation models are not adequately constrained with dynamic well data early in the production life of the reservoir.
Cement Packer Installation in Highly Deviated Well Using the Balanced Hydrostatic Plug Concept through Coiled Tubing: Offshore Niger Delta
Authors: Onuh Haruna , Abdulsalaam Ilyas , Abdurahaman Fatima , Osarowaji Emmanuel , Chemmarikattil Rohan , Ibrahim Charles , Ntiwunka Greg
Published: July 2019

The "balanced cement plug" concept has long been a standard industry practice for setting plugs in a wellbore. This requires setting a hydrostatic plug consisting of a column of brine, spacers, and cement slurry pumped into the annulus of a tubing/drillstring to create a balanced U-Tube that equates the hydrostatic head in the drillstring/tubing and annulus. Fluid volumes are calculated accounting for fluids both inside and outside the pipe at the given gradient, thus resulting in a hydrostatically "balanced system."

Recently, this technology has been successfully deployed for cement packer design and execution using coiled tubing (CT) at a depth of 1,899 ft above the production packer with 111 bbl of calcium chloride brine existing (cement accelerator) below the tubing punch interval in the tubing-casing annulus. The cement packer installation design was for accessing bypassed hydrocarbon in high-angle (65 to 72º) deviated wells offshore the Niger Delta. Design considerations are reviewed and precautions for placement of high angle cement packer through CT are discussed.

Initial designs to isolate the lower depleted zone were futile because of failed zonal isolation with mechanical plugs. Thus, an attempt to isolate the lower interval by pumping cement with 15% excess (openhole volume) led to having 17 bbl (1,899 ft) of cement within the 3.5-in. production tubing, and above the production packer. The CT deployed cement packer installation without a cement retainer presents unconventional solutions for placing cement at the height of 1,899 ft. The operation was successfully executed and the temperature log confirmed top of cement as proposed during the design phase. The holdup depth in the tubing was also tagged as expected with no cement U-tubing from the annulus. Post-job shut-in tubing and casing pressures, quantity of cement pumped, and flow testing have proven the success of the design and procedure implemented in challenging wellbores.
The Loss of Primary barrier: An Integrated Approach of Downhole Leak Location and Quantification. Case Study
Authors: Volkov Maxim , Yurchenko Andrey , Ellis Remke
Published: July 2019

Failure of the primary barrier in most cases results in observable sustained annulus pressure. For other such cases, sustained annulus pressure may not result, and leak associated fluid movement remains confined to deeper intervals, for example as cross flows.

This manuscript introduces a comprehensive approach to assess the current status of primary and secondary barriers and, for this case of integrity loss, to quantify the downhole leaks rates. The assessment includes: Determining individual pipe wall thickness of first two concentric metal barriers using electromagnetic pulse logging techniqueSpectral Noise Logging to locate the active leaks and to verify the sealing integrity of cement barriersHigh Precision Temperature logging for downhole leak rate quantification utilizing temperature modeling

The paper contains the physics of measurement, lab and field tests of the barrier assessment technologies, followed with a case study: A single string gas producer, with sustained A-annulus pressure. Additional survey findings allowed the identification and quantification of a crossflow resulting from leaks.
Defining the Optimal Development Strategy to Maximize Recovery and Production Rate from an Integrated Offshore Water-Flood Project
Authors: Abdulfatah Hajara Kabeer , Stanley Okafor Ikechukwu , Nzerem Petrus , Jakada Khaleel
Published: July 2019

A reservoir development plan provides the necessary guidance and information for establishing whether or not a project is economically viable considering possible development project options, risks and uncertainties in order to define the most optimal development concept that will increase oil production and reduce production costs. The aim of this project was to determine the optimum way to develop and produce an offshore oil field in a manner that considers risks and uncertainties and values stakeholders’ interest. A stochastic multi-tank reservoir model was created using MBAL and it consist of various producers and water injection wells. Sensitivity analysis was carried out on Seven development scenarios with a view to examine effect of maintaining reservoir pressure, sustaining well productivity and injectivity, optimize well counts and improving well delivery- timing, cost and well performance. The economic viability of each of the development scenarios was carried out to determine the net present value, incremental project cash flow, unit technical cost, unit development cost and breakeven price BEP of each of the scenarios. The optimal development strategy was then selected based on the production performance and key economic indicators. The project provided an opportunity to develop an additional 396MMbbls of recoverable oil from 32 new wells both producers and injector wells (P+WI).
The Impact of Reservoir Heterogeneity in the Modelling of Scale Inhibitor Squeeze Treatments
Authors: Uzoigwe Friday , Mackay Eric J. , Vazquez Oscar
Published: July 2019

The oil and gas industry require technologies to prevent mineral scale formation and deposition in reservoirs and production systems. One commonly used method to achieve this is the scale inhibitor squeeze treatment. The challenge addressed here using modelling is to prolong the squeeze treatment lifetime in heterogeneous reservoirs, thus, reduce the cost per barrel of oil produced, especially in deep offshore and remote locations.

Key to squeeze life extension is ensuring optimum scale inhibitor retention on rock matrix. Therefore, the inhibitor must contact the reservoir rocks and be distributed amongst the layers in proportion to the expected water production rates per layer, which will be determined by reservoir heterogeneity, system geometry and gravitational effects. These effects are studied for an offshore water flooded reservoir by means of a reservoir simulation model.

The study reveals that reservoir heterogeneity generally improves inhibitor squeeze treatment performance as measured at surface for the entire well, with more inhibitor being placed in the zones with high permeability-thickness product (kh). However, downhole pressure differentials can result in higher pressure layers being unprotected for longer periods before the inhibitor concentrations for the entire well goes below the Minimum Inhibitor Concentration (MIC).

The use of diversion techniques is shown by simulation work to improve placement and thus help achieve a successful inhibitor squeeze treatment in all the reservoir layers. However, inhibitor concentrations may remain relatively high in layers that do not produce much water, resulting in some wastage of inhibitor as a penalty for delaying the time before re-squeezing is required.

The modelling helps understand where scale could occur and the best management strategy for scale prevention or control; identifying the impact of scale; giving insight into the best inhibitor squeeze treatment options and expected performance; and providing input needed for the economic model required for good reservoir scale management.
Application of Geographically Weighted Regression to Model the Effect of Completion Parameters on Oil Production – Case Study on Unconventional Wells
Authors: Wigwe M. E , Watson M. C , Giussani A. , Nasir E. , Dambani S.
Published: July 2019

Spatial data exists practically everywhere, including the oil and gas industry. Several factors drive the distribution of the location of oil and gas wells: performance of existing wells, available acreage, need for operators to maintain a certain amount of production and to stay competitive. Some of the important parameters to consider in the design of a completion job for an unconventional oil and gas well are the length of lateral (and by extension perforated interval), number of stages, total pounds of proppants, total volume of fluid pumped, injection pressure and injection rate.

In big data analytics and building of a regression model to capture the effects of these parameters on oil production, the practice has been to analyze wells in similar formations or similar basins, even when these wells are miles apart. Due to the presence of spatial autocorrelation and non-stationarity in such data, the recommended practice should be to take these spatial dependencies into account by using geographically weighted regression (GWR).

In this paper, we present an application of GWR in location-based regression modeling to capture the effect of these completion parameters on the first six months of oil production in 5700 wells in the Bakken and Three Forks formation in North Dakota. GWR builds different models for every location, leading to a spatial distribution of variable coefficients. This model is well suited to capture both local and global variations in our dependent variable. We also compare the results obtained with that of three other models: multiple regression model, artificial neural network model and universal kriging. Just like the use of kriging, GWR model resulted in a much-improved prediction of oil production as captured by the goodness-of-fit diagnostics (R squared, AIC, and RMSPE), compared to the other two non-location-based models. We recommend the use of the GWR model in the prediction of oil or gas production when spatial non-stationarity exists.
The Application of Holistic Workflows for Sour Reservoir Management on the X Field
Authors: Kuku O. , Ekeigwe A. , Ajakaiye G. , Olushina T. , Harper C. S. , Zheng Y. , Green S. A.
Published: July 2019

The X field has been in production since 2011 and some of the reservoirs are on a water flooding-scheme for pressure support. The water flood commenced solely with the injection of seawater and more recently commingled produced water and seawater. A few years into the production, it was observed that production from at least one of the reservoirs has become sour.

Thus, a reservoir souring study of the X field was conducted to ascertain the immediate cause of souring, determine future sulphide production trend and provide recommendations on sulphide concentration and integrity monitoring, bacteria monitoring practices and mitigation against the current souring events on the X field.

The study was conducted by a joint team from Oriental Energy Resources Limited (OERL) - operator, Baker Hughes, a GE company (BHGE) in collaboration with the regulatory agency, the Department of Petroleum Resources (DPR).

The study utilized BHGE proprietary workflows, including those previously documented in SPE-179921-MS, and drew on significant routine operational data, and specialized data such as sulphide and sulphate isotopes, detailed water compositions (including Volatile Fatty Acids -VFA), serial dilution and molecular microbiological enumeration techniques and microbiological sequencing techniques.

The study concluded that the primary source of souring was microbiological and that this souring event was not limited to the focus, high H2S reservoir (XY) but was observed to be present on all water injected reservoirs in the X field. It was felt, though not proven, that the Sulphate Reducing Bacteria (SRB) may have been derived from the seawater. The microbiological Deoxyribonucleic Acid (DNA) analyses indicated that the primary carbon source, once VFA had been sufficiently depleted, was likely to be the biodegradation products of hydrocarbon degrading bacteria within the reservoir.

The study also concluded that, due to the lack of carbon source constraint for the bacteria, the required inhibitory nitrate dose rates would be uneconomically high and would yield no benefit over the effects of replacing Sea Water Injection (SWI) with Produced Water Re-Injection (PWRI). However, it has been observed that sulphate concentration in production had declined since the cessation of seawater injection.

The reservoir souring study has resulted in a heightened level of surveillance, thereby leading to a safer operating environment on the X asset. The field operating strategy and chemical application has been modified to allow the overall magnitude of sulphide related hazards and cost of operating the field to be reduced.

This project is a first in the Nigerian oil production operations, involving an open collaboration between an operator, a government body and a service vendor on reservoir souring.
Third Party Tariff: A Key Input to NOV Projects Decision Analysis & Decision Quality
Authors: Obeahon P. P. , Ikpera C. N. , Laoye A. O.
Published: July 2019

The paper seeks to find the optimum solution on how to develop some portion of a unitized field. The case study involves two fields straddling across four oil mining leases (OMLs), in Niger Delta, Nigeria. Each field were operated independently by JV-A and JV-B until mid-2016 when the operatorship of the straddling reservoirs (SRs) in the unit was granted to JV-B by the regulators, as it is a law in Nigeria that all straddling reservoirs should be developed as a unit under a single operator.

The decision on whether JV-A should grant JV-B the right to also operate the non-straddling reservoirs (NSRs) in the unit will depend on the amount of tariff imposed. JV-A will be required to pay hydrocarbon transportation and processing tariffs if it flows its share of the produced hydrocarbon through JV-B's existing facility. The exact amount of tariff is unknown and will be negotiated. Additionally, four feasible evacuation routes exist and will be considered for this evaluation to decide the most profitable and capital efficient investment option.

The result shows that the opportunity is very sensitive to hydrocarbon handling tariff; necessitating JV-A choice of evacuation route. In addition, the paper demonstrates how using appropriate project framing and considerations of who will operate the JV-A's non-straddling reservoirs, relied heavily on different hydrocarbon transportation and processing tariffs. It is hoped that this paper having highlighted the importance of tariff charges and the role of proper framing on decision quality will encourage decision makers to adopt this approach during decision analysis and ultimately improve the quality of investment decisions particularly for Non-operated venture (NOV) projects.
Effective Barrier Risk Management in Process Safety Utilizing the Bow Tie Methodology
Authors: Abia D. , Iwegbu M. , Onofeghara C. , Anozie I.
Published: July 2019

The outcome of the Technological Risk Assessment is the major risk register that contains all the major incident scenarios including the top ten scenarios and their corresponding barriers towards prevention, control & mitigation of potential consequences. The expected result of an effective Barrier Risk Management is to reduce and or minimize the possibility of a major process safety incident happening due to weaknesses developed in these barriers and ensuring that all the necessary mitigation and mechanisms are robust enough and in place should an incident happen. Are our Barrier risk assessment for process safety accidents properly assessed with adequate barriers defined to prevent the occurrence of major incidents?

This means that, the assurance of Process Safety is defined on the basics that all our Safety Critical Barriers (SCBs) are clearly understood, by knowing what our critical controls are, assessing and monitoring their health status in our day-to-day operations towards ensuring that they are functionally available on demand to prevent, mitigate and control process safety incidents.

This Paper in detail, will describe the operationalization of the Bow Tie Barrier Risk management, beginning with the Identification of Safety Critical Barriers for operating plants in an integrated approach, defining potential threats from major accident scenarios, its effects and their barriers in one holistic view with the BowTie, act as a line of sight for individual barrier performance management, action plans and improvement. Converting the BowTie from a static to a dynamic barrier management tool by identifying any missing or possible degraded barriers and manage corrective actions implementation, plug in other operational elements such as incidents, audits, inspections, change management and safety and inspections information to create relationship between the barriers and any operational disturbances.
Best Practices in Evaluating Production Performance: A Niger Delta Case Study with Inter-Reservoir Communication
Authors: Mogbolu Emmanuel , Awa Chukwunweike , Ekwealor Jude , Jaja Victor , Okereke Onyedikachi
Published: July 2019

Uncertainty management for resource volume of a brown field is relevant. An analytical approach via dynamic model was used to evaluate this impact on a developed gas reservoir (brown) by two other reservoirs. One of them is a green oil-rim reservoir, while the other is a developed oil reservoir. This is due to sand-to-sand juxtaposition with the two reservoirs. Integration of available data over time, while considering all the reservoir uncertainties was adopted. This was buttressed by the continuous production from the gas reservoir, that had already gone past the initially evaluated Gas Initially in Place (GIIP).

The brown reservoir is a highly faulted gas reservoir with twenty-seven (27) years production history, by seven wells. The reservoir's GIIP re-evaluation had been done twice over the years. This was because it had fully developed its ultimate recovery, with three wells still producing. This GIIP re-evaluation approach could no longer be utilized, as it had very good well coverage.

Fault seal analysis, pressure, PVT sample and log data taken over time reveal the likelihood of communication across the stacked reservoirs. A multi-tank material balance model (MBAL) was built via a multidisciplinary approach. The model was history matched using an experimental design approach that saved time and contacts were calibrated. The result showed the quantity of hydrocarbon in both reservoirs that have flowed into the developed gas reservoir. This provides a snapshot on the resource volume impact of the reservoirs with respect to their development and uncertainty management. Revised development plans and resource booking for the reservoirs are also study outcomes. This is relevant for business decisions on resource volume booking and reservoir management.

This approach is a quick win within the Well, Reservoir and Facility Management (WRFM) workspace. Further work by building a 3D simulation model and pressure data acquisition is required for robust benchmarking.
Development of a New High-Pressure High-Temperature Technology for Advanced Screening of Biosurfactants and Injection of Microbes in Porous Rocks during Low-Salinity EOR Processes
Authors: Onyemara Chibuzo C. , Akanji Lateef T. , Ebel Rainer
Published: July 2019

A new high-pressure high temperature (HP-HT) lab-scale rig involving microbial cultivation of pure bacteria strain under reservoir conditions of up to 200 bar and 200°C has been developed. This was accompanied by an extensive laboratory investigation to establish the mechanisms associated with the production and screening of Lipopeptide from pure Bacillus mojavensis NCIMB 13391 strain for the purpose of enhanced oil recovery (EOR) processes. We report for the first time, thermodynamic standard Gibbs free energy required for the Lipopeptide environment friendly biosurfactant (EFBS) formation (ΔGf°) as -2135.1 J.mol−1, and very low brine salinity water (VLBSW) molarity of 0.5096 mg.l− 1. The produced Lipopeptide biomaterial under anaerobic batch cultivation technique generated CMC values of 2.8 mg.l−1 and 2.7 mg.l−1 in deionised water and VLBSW respectively. The dimensionless molecular weight of the produced Lipopeptide biomaterial is 1423.69 and high spontaneity nature of the biomaterial resulting from a more negative ΔGf° value aided the interfacial tension (IFT) reduction of the heavy crude oil and VLBSW system from 15.71 mN.m−1 to 0.04 mN.m−1 at critical micellisation concentration (CMC) of 2.7 mg.l−1 and 65°C under reservoir confined environment, and 1.76 mN.m−1 at 25°C temperature and 55 bar pressure conditions. However, 2.7 mg.l−1 solution molarity, 65°C temperature and 55 bar pressure are recommended as the optimum recovery pilot molarity, temperature and pressure of the screened heavy crude oil material in low-salinity EOR processes.
The protocol to remove high abundant proteins from HIV-1 infected human plasma
Authors: Barik Sushanta Kumar , Mohanty Keshar Kunja , Bisht Deepa , Mohanty Partha Sarathi , Patil Shripad , Singh Rananjaya , Joshi Beenu , Tripathy Srikanth Prasad , Singh Tej Pal , Tandon Rekha , Tomar Sheetal , Jena Srikanta
Published: July 2019

Removal of high abundance protein from human plasma is an advantage during the analysis of protein in SDS-Poly acrylamide gel electrophoresis. We have adopted a protocol for removal of high abundance protein from human plasma by following several previous protocols. The 50% TCA-Acetone is most suitable method for removal of high abundance proteins like albumin and globulin from HIV-1 infected human plasma samples. We have developed this protocol in our laboratory for carrying out the protein work from HIV-1 infected human plasma samples. This protocol is suitable to run the purified human plasma protein for sodium dodecyl sulfate polyacrylamide gel electrophoresis.
Long-term fluoxetine administration induces changes in microtubule plasticity mediated by CRMP2 in differentiated PC12 cells
Authors: Wu Zuotian , Wang Gaohua , Xiao Ling , Wei Yanyan , Wang Huiling , Yang Can
Published: July 2019

Backgroud
Depression is a neuropsychiatric disease with a high risk of relapse. Clinical guidelines advocate whole course of antidepressant treatment, but the relapse rate of MDD is still high.

Methods
We intended to study the changes in microtubule scaffold plasticity induced by long-term antidepressant administration in PC12 cell to explore the possible mechanism of depression relapse.

Results
The cell activity of NC group decreased after 3 days of culture. The results of immunofluorescence showed the extension of processes was obvious on the first day in Flu group and NC group, but neurite connections were inhibited on the third day in Flu group.CRMP2 and Tubulin were co-located by IF, and Co-IP confirmed the interaction between CRMP2 and Tubulin. RT-PCR showed the mRNA expression of CRMP2 and Tubulin increased on the first and second day in Flu group, but decreased on the third day. Similarly, Western Blotting showed the contents of CRMP2 and Tubulin protein in Flu group increased on the first day, but decreased on the third day. The expression of CRMP2 and Tubulin was affected by changes in the activity of CRMP2.

Conclusions
The long-term fluoxetine administration can affect the microtubule scaffold plasticity in PC12 cell, and CRMP2 is involved in this process. This may be one of the biological bases of the high risk for depression relapse induced by long-term antidepressant administration.
Composition and density of soil seed bank in Afar Region, Northeast Ethiopia
Authors: Gemeda Wakshum Shiferaw , Woodmata Sesebe Demissew , M Tamrat Bekele , Betemariam Ermias Aynekulu , mm Wolfgang Pitroff
Published: July 2019

Background: The changeover from seed to plant is a fundamental scheme shaping plant community structure and dynamics. Persistent soil seed banks are significant as it distributes regeneration and succession throughout the year in the vegetation ecosystems following disturbances.
Objectives: The aims of our study were to analyze status of composition and density of soil seed banks (SBs) in West Afar Region, Ethiopia, and effects of Prosopis juliflora (Prosopis) on spatial distribution and densities of SBs.
Methodology: Soil samples were collected under the Prosopis canopies and non-invaded open grazing lands from area of 15cm x 15cm and soil layers of 0-3cm, 3-6cm and 6-9cm.
Findings: It was found that SBs had shown significant variations by districts (χ2 = 5.5, P =0.02) and soil layers (χ2 = 10.5, P =0.01). But, habitats did not show significant effects on SBs (χ2 = 2.3, P =0.13). Higher density of SBs 7065, 8978, and 8444seeds/m2, respectively were recovered from the soil depths of 0-3, 3-6, and 6-9cm at Teru district. On the other hand, lower densities of 311, 0, and 44seeds/m2, respectively SBs were recovered from the soil depths of 0-3, 3-6, and 6-9cm were at Yalo district. Furthermore, SBs under the canopy of Prosopis were less by 93.5% than non-invaded open grazing lands in 0-3cm soil depth. Meanwhile, SBs in 3-6cm soil depth were higher by 79% in non-invaded Prosopis than invaded areas at Teru district.
Conclusions: The overall low density of the SBs in the study areas had implications of poor range land quality for animals to feed on and consequently affects the livelihood incomes obtained from livestock of pastoralists. Thus, conservation of grazing lands, re-seeding of grazing lands, and management of the invasion of the Prosopis are vital measure to sustain the grazing areas in the region.
Comparison of Machine Learning Models and Framingham Risk Score for the prediction of the presence and severity of Coronary Artery Diseases by using Gensini Score
Authors: Wang Yao , Zhu Kangjun , Li Ya , Zhao Liding , Lv Qingbo , Fu Guosheng , Zhang Wenbin
Published: July 2019

Background: The risk prediction model for cardiovascular conditions based on the routine information isn’t established. Machine Learning (ML) models offered opportunities to build a promising and accurate prediction system for the presence and severity of Coronary Artery Diseases (CAD).
Methods: In order to compare the validation of ML models to Framingham Risk Score (FRS), a total of 2608 inpatients (1669 men, 939 women; mean age 63.16 ± 10.72 years) at our hospital from January 2015 to July 2017 were extracted from electronic medical system with 29 attributes. Four different ML algorithms (Logistic Regression (LR), Random Forest (RF), k-Nearest Neighbors (KNN), Artificial Neural Networks (ANN)) were acted to build models, based on eight core risk factors and all factors respectively. The Area Under Curve (AUC) of receiver operating characteristic curve was the significant value to show the prediction power for different models.
Results: According to the AUC, all of ML algorithms had a better prediction validation than FRS for the presence of CAD, specifically, FRS
ERRα promotes gallbladder cancer development via activating PI3K/AKT signaling pathway mediated by Nectin-4
Authors: Wang Lei , Yang Mengmeng , Guo Xingmei , Yang Ziyi , Ji Yuan , Jin Huihan
Published: July 2019

Background: Gallbladder cancer (GBC) is the most common malignant tumour of the bile duct with a poor prognosis. The estrogen-related receptor alpha (ERRα) is a nuclear receptor that has been associated with metabolic processes and cancer progression. Increased ERRα has been shown in endocrine-related cancer and non-endocrine-related cancer. Nevertheless, its role in GBC remains unknown.
Methods: ERRα expression was analyzed by immunohistochemistry in 59 GBC samples. Its association with clinicopathologic characteristics was evaluated. The effect of ERRα on GBC cell proliferation and invasion was evaluated by loss- or gain-of-function assays in vitro and in vivo. The influence of ERRα on EMT biomarkers, Nectin-4 and PI3K/AKT signaling pathway was detected by western blotting. Inhibition of Nectin-4 was conducted to explore the potential mechanism of ERRα in GBC.
Results: Our study reveals increased ERRα expression in GBC tissues vs. non-tumour adjacent tissues. ERRα expression is significantly positively correlated with high TNM stage, high invasion depth and lymph node metastasis, while negatively associated with prognosis. Targeted depletion of ERRα by lentivirus-mediated shRNA decreased cell proliferation in vitro and in vivo. ERRα promoted cancer cell migration and epithelial-mesenchymal transition by regulating the expression of EMT relevant genes. Ectopic expression of ERRα promoted GBC cell growth and invasion in vitro, while inhibiton of Nectin-4 attenuated cell growth and invasion induced by ERRα. Moreover, ERRα overexpression activated the PI3K/AKT signaling pathway while this effect can be blocked by Nectin-4 depletion. Nectin-4 was involved in the oncogenic function of ERRα to activate PI3K/AKT signaling pathway in GBC.
Conclusions: ERRα promotes GBC progression via activating PI3K/AKT signaling pathway mediated by Nectin-4. ERRα may be a potential prognostic factor and molecular therapeutic target for GBC.
A Protocol for the Development of Core Outcome Sets in Pelvic Organ Prolapse Research
Authors: Doumouchtsis Stergios , Rada Maria Patricia , Pergialiotis Vasilios , Falconi Gabriele , Haddad Jorge Milhem , Betschart Cornelia
Published: July 2019

Background
The high prevalence of symptomatic pelvic organ prolapse (POP) and the women's lifetime risk of requiring surgery, as well as the significant impact of POP on women’s health related quality of life has resulted in a variety of studies on POP interventions. A wide variety of outcomes have been reported across randomized trials evaluating interventions for POP and various outcome measures have been used. Such variation leads to a limited value of research to provide reliable evidence-based data for clinical practice guidance. The development and use of a core outcome set (COS) would help to address these issues ensuring outcomes important to all stakeholders, primarily women with POP. We aim to produce, disseminate and implement a COS for POP.
Methods
A steering group within the CHORUS, an International Collaboration for Harmonising Outcomes, Research and Standards in Urogynaecology and Women’s Health will guide the development of this COS. Systematic reviews of trials that reported outcomes and outcome measures on interventions for POP will form the basis for the creation of an outcome inventory. Core outcome selection process will be performed using an international, multi-perspective, online Delphi survey. The modified Delphi method encourages stakeholder group agreement towards consensus core outcomes through repeated reflection and rescoring of items.
Discussion
Dissemination and implementation of the resulting COS within an international context will be promoted. An embedded COS for POP within future studies will most likely be reflected by an increased value of research that provides guidance for clinical practice. The paradigm of the COS development could further inform research priorities in POP treatments, and support clinical guidelines development and better patient care.
KEYWORDS: core outcome sets, outcome measures, pelvic organ prolapse, Delphi survey, randomized trials.
Utilization and associated factors of antenatal care among women who gave birth within the last two years, in Teda Kebele,Gondar town, northwest Ethiopia
Authors: Beyene Fentahun Yenealem , Gubay Amanu
Published: July 2019

Objective

The purpose of this study was to assess utilization and associated factors of antenatal care among women who gave birth within the last two years. Three hundred fifty two participants were selected by simple random sampling technique from April 1-May -27, 2015. Bivariate and multivariate data analysis was performed using SPSS for Windows version 23.

Result

The study identified that 84.4% of respondents were utilized antenatal care.
Comparison of hospital complications and mortality for stroke patients treated by male vs female physicians: a propensity-score matched study
Authors: Lam Fai , Chen Ta-Liang , Lin Chao-Shun , Shih Chun-Chuan , Yeh Chun-Chieh , Hu Chaur-Jong , Chiou Hung-Yi , Liao Chien-Chang
Published: July 2019

Background: The association between physician gender and the outcomes of stroke patients is not yet fully understood. The aim of this study was to evaluate outcomes after stroke hospitalization between patients who received female physicians’ care (FPC) vs male physicians’ care (MPC).
Methods: We used Taiwan’s National Health Insurance Research Database 2000-2009 claims data to conduct a stroke cohort study that included 493,223 hospitalized stroke patients. Using a matching procedure by propensity score, we selected 25,160 stroke patients with FPC and 25,160 stroke patients with MPC for comparison. Logistic regression was used to calculate the adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of poststroke complications and in-hospital mortality between patients with FPC and MPC.
Results: Compared with patients with MPC, stroke patients with FPC had significantly lower risks of poststroke pneumonia (OR 0.87, 95% CI 0.81-0.94), septicemia (0.79, 95% CI 0.70-0.88), acute renal failure (OR 0.78, 95% CI 0.65-0.95), admission to the intensive care unit (OR 0.73, 95% CI 0.69-0.77), and 30-day in-hospital mortality (OR 0.64, 95% CI 0.55-0.75). However, the risk of urinary tract infection (OR 1.16, 95% 1.09-1.23) was higher in patients with FPC than in those with MPC. Lower rates of poststroke adverse events in patients with FPC were noted in further analysis, including different morbidities and various types of stroke.
Conclusions: Stroke patients with FPC showed reduced complications and mortality compared with MPC patients. Our findings warrant randomized control trials in the future to validate the influence of physician gender on stroke outcomes.