bluuebunny/crossref_metadata_2025_split huggingface dataset:
Birth Interventions Related to Lower Rates of Exclusive Breastfeeding and Increased Risk of Postpartum Depression in a Large Sample
Authors: Kendall-Tackett Kathleen , Cong Zhen , Hale Thomas W. 
Published: August 2015

Overview: This study examines the impact of birth interventions, such as epidurals, inductions, pain medications, and cesarean sections, on breastfeeding and postpartum depression with a large sample of mothers.Method: Data for the present analyses were from the Survey
of Mothers’ Sleep and Fatigue, a 253-item online survey of 6,410 mothers 0–12 months postpartum.Findings: Mothers were significantly more likely to be breastfeeding if they had unassisted vaginal births, or did not have epidurals or other pain medication during labor. Mothers
had higher depressive symptoms if they perceived that their labors were difficult and they experienced high levels of pain. They also had higher depressive symptoms if they had planned or emergency cesareans, but unplanned (nonemergent) cesareans were associated with lower levels. When multivariate
analysis was conducted, only epidural, postpartum hemorrhage, and postpartum surgery were significantly related to depressive symptoms.Conclusions: The type of birth a woman experiences influences breastfeeding and her emotional health. Contrary to previous findings, epidurals
are associated with lower breastfeeding rates and higher rates of postpartum depression. Other birth interventions and complications, such as postpartum hemorrhage or surgery, have a negative impact as well.
Drilling Deeper to Access More Hydrocarbon Potentials in the Yowi Oilfield, Offshore, Niger Delta, Nigeria
Authors: Momta Prince S. , Odigi Minapuye I. 
Published: August 2015

Abstract
Depleting reservoirs and a corresponding decline in oil production is a common occurrence in most mature fields. Efforts to improve oil production in such fields require a redesign of secondary recovery technique which only extends production life for a short time. The Yowi Field has experienced this scenario for the past one decade. This study focuses on identifying hydrocarbon potentials at deeper depth. Exploring for more hydrocarbon play to boost reserve will require searching for prospects below the intervals that have been developed in the field. Most production wells drilled in the entire field did not go beyond 9850ftmd. The interval beyond the drilled depth shows a change in depositional setting from a nearshore shallow marine realm to a deep marine depositional environment base on seismic character. The hydrocarbon play here is majorly stratigraphic elements. Using 3D seismic reflection data, reasonable hydrocarbon pools seem to occur at depth below 1400 milliseconds. Sand bodies suspected to be hydrocarbon bearing occur as discrete turbidite lobes and also as stratigraphic pinchouts against an intrusive shale diapir. The hydrocarbon bearing and porous sand units are indicated by intervals having high root-mean-square amplitude anomaly. Areas with low amplitude suggest a water-bearing or non-reservoir lithofacies units. A deeper drilling beyond 2000 milliseconds will definitely increase the reserve and production potentials of the field since there is an evidence for hydrocarbon occurrence at deeper depth, though might be over-pressured.
Cost Benefit Analysis of Vegetable Oils Used As Alternatives to Diesel in the Formulation of Oil-Based Drilling Muds
Authors: Agwu Okorie E. , Isemin Isemin A. , Akpabio Moses G. 
Published: August 2015

Abstract
When water based muds fail to ensure that a usable hole is drilled, oil based mud formulated with No.2 diesel is adopted. Because No. 2 diesel is toxic, the oil and gas industry is looking for other alternatives to it. One of such alternatives is the use of vegetable oils. These vegetable oils are relatively more expensive than the No. 2 diesel; hence their use would ultimately increase the cost of drilling fluids. There are however many types of these vegetable oils. These vegetable oils vary in physical and chemical properties and in their cost. This paper undertook an investigation into the cost, properties and availability of these vegetable oils for use in drilling mud formulation; it chronicled the trend of researches available on the use of vegetable oils as drilling fluids with the findings from each researcher presented. This paper also presents a detailed cost benefit analysis of major vegetable oils used as drilling muds. To make the work comprehensive, an evaluation of the viability of each vegetable oil to achieve the objectives of cost effectiveness, availability, and good rheological and filtration properties were evaluated. The results showed that of all the vegetable oils studied, olive oil ranked the least in meeting all of these objectives while palm oil, soybean oil followed by rapeseed oil fulfilled all of the objectives to a considerable extent. This paper therefore offers an all-inclusive portfolio of cost related issues that border on the use of vegetable oils as drilling muds which would be useful to wellbore drillers in particular and the E & P industry at large.
The Nigerian Natural Gas Industry: Critical Policies and Legal Issues
Authors: Maduekwe Nkiruka Chidia 
Published: August 2015

Abstract
Notwithstanding the fact that commercial oil discovery has been fifty-plus years in Nigeria; the Nigerian natural gas industry is known to be a developing industry. Thus, understanding the huge potential this industry presents to its economy, the Nigerian government has sought to implement policies that will bring about development in this industry. The paper seeks to examine the policies and the legal framework (if any), in order to ascertain to what extent the policies have been able to develop the industry and if not, why? In addition, the paper examines the adequacy or otherwise of the present legal framework. The paper finds that the successful and sustainable development of the natural gas industry hinges on the existence of adequate legal framework, as policies can only serve as aspirations and sought-after-goals without the backing of sufficient legal framework to support their implementation. The paper finds that in light of shale gas development in Nigeria's investors cum market geography, time is fast running for Nigeria as there is the urgent need to address the situation as Nigeria is gradually losing not just investors but her natural gas market as well.
Gas-Oil Gravity Drainage and Reinfiltration in Naturally Fractured Reservoirs
Authors: Udoh Francis D. , Igbafe Anselem I. , Okon Anietie N. 
Published: August 2015

Abstract
The prediction of production performance in naturally fractured reservoirs is dependent on reinfiltration and capillary continuity phenomena. In fractured reservoirs, reinfiltration and capillary continuity phenomena have been the major setback during gas-oil gravity drainage. The oil contained within the matrix of the gas invaded zone begins to drain down into the fracture system and into the lower matrix blocks, due to the force of gravity. Some of the oil that is drained out of the upper matrix blocks can reinfiltrate into the lower matrix blocks from the top or side surfaces and can flow down through the areas of contact between blocks. To evaluate the effect of reinfiltration in gravity drainage mechanism and fractured reservoir parameters: fracture width (bf) and storativity capacity (ω) on reinfiltration process, a fractured porous media was modeled with ECLIPSE-100 Simulator. The base-case simulation runs (SIM-1 and SIM-2) showed that 55.14% and 53.40% of the oil in-place in the modeled fractured porous media were recovered by gas-oil gravity drainage mechanism without reinfiltration and with reinfiltration, respectively. Furthermore, the sensitivity study of the aforementioned fractured reservoir properties on gas-oil gravity drainage and reinfiltration with simulation runs (SIM-3 through SIM-10) indicate that fracture porosity as well as storativity capacity influence the ultimate oil recovery in naturally fractured reservoirs. Additionally, the fracture width has no influence on gas-oil gravity drainage and reinfiltration in the modeled fractured reservoir. Therefore, gravity drainage recovery mechanism proliferation is affected by oil reinfiltration within the matrix blocks that resulted in 3.173% production reduction. Hence, fracture porosity and storativity capacity are considerable factors in reinfiltration mechanism in naturally fractured reservoirs.
Integrated Reservoir Modeling and Uncertainty Assessment of a Reservoir Complex in the Niger Delta
Authors: Anyanwu Chinedu , Afekhume Daniel , Onobrakpeya Collins , Sonde Adenike , Kakayor Omagbemi 
Published: August 2015

Abstract
Critical decision making with limited information and associated uncertainties is a challenge at every level of the hydrocarbon value chain. This is even more so at early stages of field development projects when geosciences and engineering data are sparse and the understanding of the geological complexities is still limited. Thus, the need for building multiple realizations of representative reservoir models that captures the full range of subsurface uncertainties is crucial to ensure a robust decision-making process.
From previous studies, the Reservoir Complex, X is highlighted as a stack of two gas-bearing reservoirs that merge to form a doublet as observed on seismic and share a common contact towards the flank of the structure. This interpretation informed the modelling of both reservoirs as a single mega unit. An Integrated Reservoir Modeling approach rather than a discipline-focused one was adopted to evaluate the range of uncertainties in the reservoirs. For this study, a multidisciplinary subsurface team built a scenario-based model and performed Sensitivity analysis to identify key uncertainties on input parameters that are most impactful on in-place volumes and recoverables.
This paper discusses techniques employed in building the static/dynamic models, generating estimates for the various uncertainties and how these were analyzed to identify the ‘heavy hitters’. Results from this study identified Structure, Net-to-Gross and Porosity as the top three uncertainties with most impact on static volumes while Structure, PVT and Aquifer size have most impact on recoveries.
Deterministic low, base and high case In-place volumes computed are 509, 627 and 769 BScf while recoveries were 182, 339 and 643BScf respectively. Probabilistically, the in-place volumes were 336, 480 and 634 Bscf while the recoverables were 205, 348 and 550 Bscf respectively.
Modeling Petrophysical Property Variations in Reservoir Sand Bodies Using Artificial Neural Network and Object Based Techniques
Authors: Osarogiagbon Augustine Uhunoma , Udeze Chima Cyril , Imorame Imonitie Jude 
Published: August 2015

Abstract
This study aims at reducing uncertainty in the prediction of petrophysical properties (porosity, water saturation and net to gross) of a field at locations that do not have well data by employing geostatistical simulations, artificial neural network and object facies modeling techniques in modeling the petrophysical property variations across a field. The project has an objective of establishing standard workflows that can be adopted in modeling petrophysical property variation in a field. Four classes of model were developed which are: the pure artificial neural network model, the pure variogram model, the collocated cokriging model and the bivariate cross plot model. The Gullfaks 3D seismic data, Checkshot data and Well log was used in implementing the project using the Petrel 2013 Software.
Stratigraphic modeling, seismic interpretation, Depth conversion and 3D Grid Construction were done to provide an appropriate 3D Grid Structure for Petrophysical modeling. Facies and Petrophysical properties were interpreted at well locations inorder to provide data for modeling facies and petrophysical properties in 3D. The Truncated Gaussian Simulation was used in modeling the Gross Depositional Environment in order to provide an appropriate framework for 3D Facies modeling using Object based techniques.
The Pure artificial neural network petrophysical models were generated using 3D Seismic data and petrophysical interpretations at well locations, the pure variogram models were developed using the Object facies model and petrophysical interpretations at well locations, the collocated cokriging models were generated by combining the variogram approach and the pure artificial neural network models using collocated cokriging and the bivariate cross plot models were generated by combining the variogram approach and the artificial neural network models using back propagation from their bivariate cross plot.
The pure artificial neural network models gave the best prediction for porosity, net to gross and water saturation closely followed by the bivariate crossplot model for porosity and net to gross, the collocated cokriging model came second for water saturation prediction accuracy however, the pure artificial neural network model lacked geological patterns of facies which should naturally be present for porosity and net to gross, The pure variogram and collocated cokriging showed the region of oil water seperation more clearly than the artificial neural network method. Appropriate combination of these methods is therefore required for optimal Petrophysical property modeling.
Fracture Optimization for Multi-stage Fractured Horizontal Well with Time & stress-sensitive Parameters
Authors: Dou Xiangji , Liao Xinwei , Hou Tengfei , Zhao Tianyi , Zhiming Chen , Ren Weiyan , Zhang Rui 
Published: August 2015

Abstract
It is widely acknowledged that the conductivity of fracture is influenced by both effective stress and producing time. As a result of dynamic conductivity, the permeability-dependent non-Darcy flow in fracture is also time&stress-sensitive. In this paper, the variations of conductivity and non-Darcy flow velocity coefficient on both time and stress are taken into account to contribute to hydraulic fracture optimization.
The relationship between core permeability and effective stress is first investigated with laboratory experiment, which is modified by taking overburden stress into consideration and conducting core aging treatment to eliminate interspaces. Then, both stress-sensitive and time-sensitive of fracture conductivity is discussed with relative experiments. A new production data analysis method is also proposed to assist in time&stress-sensitivity determination. Afterwards, numerical simulation method together with a simplified economic evaluation procedure is presented to evaluate the impact of unfixed fracture conductivity and non-Darcy flow on fracture optimization.
With laboratory experiment, we find that after taking overburden stress into consideration and conducting core aging treatment, the stress-sensitive of core permeability is weaker than traditional expected result. Besides, the fracture conductivity change exponentially with stress while logarithmically with producing time. However, the combine effect of stress and time should be determined with the modified production data analysis method. Based on numerical simulation and economic evaluation, we come to the conclusion that due to the unfixed fracture conductivity and non-Darcy flow, the fracture conductivity designed should be higher than the value obtained with conventional methods.
Technical contributions in this paper including (a) investigating relationships between stress and reservoir/fracture permeability with modified experiment procedures; (b) discussing the combine effect of stress and time on fracture conductivity; (c) unfolding the impact of time&stress-sensitive conductivity and non-Darcy flow on well performance and fracture parameters optimization.
Work Flow for Reservoir Study and Challenges
Authors: Sylvester Okotie , Buduka Stanley , Bibobra Ikporo 
Published: August 2015

Abstract
The management of oil and gas reservoirs is a dynamic process that require the cooperation of technical, operating, and management groups for the success of petroleum assets. It is a team that consists of robust seismic, geophysics, geology, petrophysical analysis, drilling, logging, geochemistry, reservoir engineering and reservoir management groups to mitigate the effects of uncertainties in reservoir characterization and flow processes via collection and analyses of key geologic, reservoir, and performance data through a logical application of multidisciplinary technologies. Thus, this paper presents a concise reservoir study workflow and challenges to assist new reservoir simulator users and a check for experts in this field with a detailed description of the activities involved in a complete reservoir simulation process from initialization, history matching to predictions. This was achieved by carefully considering the step by step process involved and the data required at each stage of the reservoir model building.
Decline Curve Analysis using Combined Linear and Nonlinear Regression
Authors: Ukwu Austin K. , Onyekonwu Mike O. , Ikiensikimama Sunday S. 
Published: August 2015

Abstract
The varieties of methods for predicting oil well performance are material balance analysis, decline curve analysis and numerical reservoir simulation. Among the techniques, the decline curves have been found quite simple and accurate to forecast oil well performance in the absence of known reservoir parameters. The basic concept of the Arps' hyperbolic decline curve analysis is nonlinear curve fitting. However, the difficulty of finding a proper nonlinear algorithm to tune the Arps' hyperbolic decline equation to match historical oil production has forced analysts to use the exponential and harmonic declines, which are adjudged the approximate limiting cases of the Arps' hyperbolic decline. So, this study advocates a shift in paradigm; that is the use of nonlinear regression algorithm to tune the Arps hyperbolic decline equation initialized from linear curve fitting. The hyperbolic equation was expressed as a linear relationship in terms of the first derivative of production rate with respect to time. The first derivative was obtained from natural spline interpolation which greatly improved the quality of the initialized decline parameters and the accuracy of the decline curve analysis.
Gas well Test Interpretation: Niger Delta Field Experience
Authors: Obeahon P. P. , Daodu O. , Sedgwick A. 
Published: August 2015

Abstract
This work details how production data, well test analysis and PVT data analysis can be used to evaluate the effects of near wellbore condensate accumulation on well productivity for a green field in the Niger Delta. The field, comprising shore-face deposits that were later cut by channels in a high-energy deltaic setting. Prior to this study, six wells had been drilled. Wells -1 and -2 had exploration and appraisal objectives while wells -3, -4, -5 and -6 had development objective. After drilling wells -3, -4, -5 and -6, MRT were conducted on these wells with the key objective of verifying analogue based well deliverability.
The following conclusions arise from the interpretation of the test data. Well-3 will deliver at a lower rate of 50MMscf/day as opposed to the pre-test estimate of 100MMscf/day. This is due to higher Darcy and non-Darcy coefficients. Furthermore, flowing bottom hole pressure recorded during testing and from the first four months of production indicates that the reservoir was been depleted below the dew-point pressure of 4724 psi by about 100 psi. These observations, in combination with declining productivity index and producing condensate-gas ratio suggest that condensate dropout is most likely responsible for the high skin, hence well-3 potential was revised from MRT interpreted estimate of 89MMscf/day to 50MMscf/day. This decrease in well potential from 100MMscf/day to 50MMscf/day decelerated gas recovery by about 3 years.
Well-4 data interpretation indicated low non-Darcy skin and Darcy coefficient. Single pressure build-up (PBU) interpretation indicated pressure leaks into the casing-tubing annulus, an inference substantiated by the observation of consistent high casing-head pressure in the well. Possible causes of high casing-head pressure were investigated and attributed to poor tubing connection.
Both wells 5 and -6 penetrate the same sand. A four-point test was performed on Well-6 while performing PBU on Well-5 hence no pressure stabilization on these well due to Interference effect. Interpreted results indicates that Well-5 has a higher Darcy skin and lower non-Darcy coefficient compared to Well-6, with both wells expected to deliver the planned offtake rates of 100MMscf/day within acceptable drawdown limits.
This work identifies dew point pressure as an extremely important factor to consider when designing gas well test, generating deliverability envelopes and optimizing condensate recovery as productivities can be reduced by 50% when condensate banking begins.
Formulation of Local Alkaline- Surfactant-Polymer (Asp) For Enhanced Oil Recovery in Niger Delta: A Review
Authors: Uzoho C. U. , Onyekonwu M. , adnAkaranta O. 
Published: August 2015

Abstract
The Niger Delta basin has being producingfor over 50years using primary recovery method. It is gradually advancing into secondary oil recovery stage after which the tertiary oil recovery techniques will be exploited. The primary and secondary recovery methods are only able to recover about 30–35% of oil from the reservoir leaving the 65–70% trapped. As the demand for energy and the cost of drilling increases globally, there arises the need to squeeze the bottom of the barrel. Chemical processes is one of the tertiary recovery techniques which involves the use of chemicals (Alkaline, Surfactant, and Polymer) for enhance oil recovery but these synthesized chemicals are imported and expensive. Several researchers have shown that Alkaline-Surfactant-Polymer (ASP) blends have high potentials to enhance oil recovery through a combination of the positive effects of these three types of Enhanced Oil Recovery (EOR) agents. Research had also shown that local materials in our environment can enhance oil recovery. This review paper outlines local materials that have being in use in the formulation of ASP for EOR. Challenges involved in using these local materials are also outlined. One of such challenges is that most of thesematerials are also used as food. The use of agro-wastesfrom plants that have similar characteristics as the consumable local materials for the formulation of local ASP is proposed. These agro-wastes provide salinity tolerance and are stable at high temperature when compared with synthesized chemicals. Their utilization will minimize production cost as their cost will be theoretically independent of oil price, maximize profit, convert waste to wealth and create job opportunities for Nigerians.