bluuebunny/crossref_metadata_2025_split huggingface dataset:
How Economic is Steam-Assisted Gravity Drainage for the In-situ Development of the Nigerian Bitumen Deposit?
Authors: Lawal Kazeem A. 
Published: August 2012

Abstract
This paper details a preliminary evaluation of the economics and commercial risks of deploying the steam-assisted gravity drainage (SAGD) technique for the in-situ extraction of the oil component of the Nigerian tar sands. The workflow consists of parameter screening, experimental design, response-surface generation and Monte-Carlo simulation. With the net present value (NPV) as the objective function, we evaluate the impacts of the reservoir models (oil production and steam-injection profiles), project costs, hydrocarbon (oil and gas) price and the fiscal regime on project economics and commerciality.
Within the range of parameters investigated, the uncertainties associated with the reservoir model, oil price, operating expenditure (OPEX) and capital expenditure (CAPEX) are found to be the main determinants of the commercial risks of the project. The fiscal policies do not appear to have much impact, at least within the parameter space examined.
Overall, it is estimated that SAGD has more than 60% chance of economic success (NPV &gt; 0), suggesting that this recovery technique is commercially attractive for the in-situ exploitation of the Nigerian bitumen deposit. The commercial prospects of this technique notwithstanding, the potential risks are highlighted, while options for mitigating such risks within the Nigerian context are discussed.
The Effectiveness of Root-Mean-Square in Sensitivity Analysis of Produced Water
Authors: Adeniyi A. T. , Adewole E. S , Olafuyi O. 
Published: August 2012

Abstract
This study examined impacts of successive iteration of root-mean-square values on matching historical data with data obtained from simulator. Root-Mean-Square (RMS) is simply the magnitude of a set of numbers. The magnitude is a difference between two data sets, which was reduced. An RMS value of 24.389 was reduced to 20.788 and then to an acceptable value of 11.72. A match obtained was used to make 10 years forecast with a fluid rate of 500stb/day and 1500stb/day for two predictions. Results obtained from one of the simulator's predictions were compared with a third-order degree polynomial. It is required to identify regions whose faults have significant contribution to produced water volume. This is necessary because some faults do have zero transmissibility. Region with zero transmissibility sealing fault cannot be produced by flooding across the region. Inactive faults were identified through sensitivity analysis; it was discovered that bottom and flank water entered the region through the left flank and vertically upward from the bottom.
Historical data of produced water were eventually matched with that simulated at an RMS value of 11.72 to generate future data for Sagbama. Sagbama is a name given to a hydrocarbon reservoir with the following characteristics: 16,404.2ft by 16,404.2ft by 197.85ft, gridded into 1,640.42ft in x-direction, 1,642.42ft in y-direction, and 49.212ft in z-direction. It consists of live oil and gas with unknown volume of bottom water drive. Densities of oil, water, and gas under consideration are 749.389 kg/m3, 1000 kg/m3 and 1.11242 kg/m3 respectively. Reference pressure was 400bar and rock compressibility took a value of 4.0E-5/bar. Datum depth of 3000m with 331.65bar as it the pressure at the datum, depth to gas-oil contact was 3000m without capillary pressure.
Determination of Abandonment Reservoir Pressure, GOR and BSW for Well Performance Evaluation
Authors: Dike Francis , Aboaja Ugochukwu , Ogunlade Kayode , Kefe Amrasa , Osho Rotimi 
Published: August 2012

Abstract
Well performance evaluation and prediction via decline curve analysis (DCA) requires defined abandonment conditions (Abandonment BSW and oil rate) to estimate the developed ultimate recovery (DUR) of a drainage point. Abandonment BSW and oil rate are derived from well models which require abandonment reservoir pressure and Gas-oil-ratio (GOR) among others as inputs. Good understanding of the performance of a reservoir is necessary for the prediction of abandonment GOR, and this prediction requires a systematic approach. The assumed value of producing GOR has a direct impact on the magnitude of the hydrostatic and dynamic pressure loss in a production tubular and hence it is a very important parameter in the vertical lift performance of a well. Similarly, the the reservoir pressure at abandonment is an indication of the energy available from the reservoir for lift hydrocarbon fluid s from the bottom of the producing wells. This paper illustrates the methodology employed for the estimation of abandonment reservoir pressure, GOR and BSW in support of well performance evaluation and reservoir management. Case studies for saturated and undersaturated reservoirs with weak-to moderate aquifers are considered.
Understanding Crude Oil Price Variation Using Time Series Analysis
Authors: Torkowei Biu Victor , Ikiensikimama Sunday Sunday 
Published: August 2012

Abstract
Historically crude oil prices show characteristics of seasonality, fat tails, time-variant volatilities and asymmetric distributions. Irrespective of its volatility, the single point value approach is the most widely used in evaluating profitable prospect which do not give a clear understanding of some of the key historical parameters driving its constant swings.
This work is to model oil price variation using time series analysis in order to explore whether the stochastic oil prices exhibit similar ARIMA model with the dependant parameters. This provides a clear understanding of the intrusive characteristics of the stochastic oil price in relation with the dependent parameters. The Akaike's Information Criterion (AIC)/ residual variance was used to select the ARIMA models for the dependent parameters investigated in comparison with the oil price before subsequent forecasting.
Result using the AIC/variance indicates ARIMA (1, 0, 0) with constant as the likely model for the volatile oil price, oil demand, production, world rig count, OECD consumption and population depicting their interdependent. However the likely model for the cost oil, non-OECD consumption and population differ completely which indicates that they are spot price independent. Estimated derivative instrument i.e. actual and optimistic value show a continuous rise in crude oil price of 4% annually (average oil price of $85 and demand 91 million bbls forecasted) which is a more realistic baseline for investment decision when compared to the single point value used.
Challenges, Risks and Opportunities of Mature Field Further Development: A Niger Delta Case Study
Authors: Sarkar A. , Nanpan M. , Peacock A. , Ebufegha A. 
Published: August 2012

Abstract
Identifying further development opportunities in terms of infill well drilling targets to improve recovery in matured Niger Delta fields pose significant challenges. The remaining unswept oil targets carry large uncertainties and risks associated with many sub-surface complexities and often limited and/or inconsistent surveillance data. This paper presents a case study of identifying infill opportunities in the 35-year old Niger Delta A1 field and describes how a pragmatic approach to integrated modeling and uncertainty management resulted in a robust phased further development plan which attempts to mitigate risks.
Niger Delta A1 field is a vertically stacked sequence of reservoirs. Production has occurred from nine oil bearing sands, in the depth range 6,400 to 8,400 ftss, which have strong aquifer support. The average porosities vary from 23-30% and permeabilities from 1000-5800 mD. The oil densities vary from 20-27° API. The current (Dec., 2011) recovery factors range from 25-56%.
Integrated static and dynamic reservoir modeling indicated further development opportunities in five of the vertically stacked reservoirs. The key uncertainties were the top structure of the reservoirs, current oil-water contacts, sand qualities and aquifer definitions. History matching of production data were carried out to narrow down the location of unswept oil, however, large uncertainties remained. Modeling indicated that the overall recovery from the field could potentially be increase by 6% from drilling four infill wells with 7 drainage targets. Risk mitigation measures include a focused data acquisition plan to calibrate the current fluid contacts and drilling wells targeting two sub-surface locations with dual or sequential phased development. Production data analysis indicates that the recovery factors and well recoverable volumes are highly correlated to average net oil pay. The correlations may be used for reserve QC.
Hydraulics Optimization For Efficient Hole Cleaning in Deviated and Horizontal Wells
Authors: Ogunrinde J. O. , Dosunmu A. 
Published: August 2012

Abstract
Efficient cuttings transport and hole cleaning is a very important factor that must be considered during drilling operations. In inclined and horizontal drilling, hole cleaning is a common issue since there is high tendency for formation of cuttings bed in the hole which can lead to several complex problems. The optimization of cuttings transport depends on so many factors like hole angle, cutting size, drill string rotation, drill pipe eccentricity, bit hydraulics etc.
This paper is designed to examine critical factors that affect the efficient cleaning/transport of cuttings and bit hydraulics in inclined wells with a view to understanding how to minimize drilling difficulties thereby reducing non producing time (NPT) during drilling operations.
The developed model ensures proper hole cleaning in the critical hole angle (between 45° and 60°) as well as horizontal wells and determining the optimum flowrate and rate of penetration (ROP) that will ensure successful drilling. The model also helps to save time wasted when we encounter problems of high concentrations of cuttings which causes high Equivalent circulation density (ECD) that can result in lost circulation problem amongst others.
Finally, the developed model is validated using field data and graphs showing how the penetration rate increases as cuttings concentration in the annulus reduces thereby optimizing drilling operations.
Estimating the Effects of Ethane and Heavier Components Recovery on the Heat Content of Residue Gas
Authors: Bahadori Alireza 
Published: August 2012

Abstract
Recovery of natural gas liquids (NGL) components in gas not only may be required for hydrocarbon dew point control in a natural gas stream (to avoid the unsafe formation of a liquid phase during transport), but also yields a source of revenue, as NGLs normally have significantly greater value as separate marketable products than as part of the natural gas stream. One of the key parameters in the recovery of ethane and heavier products from natural gas is the effect of the extraction on the heat content of the residue gas. In this work a simple-to-use generalized correlation is developed for the ethane recovery limit to attain a minimum higher heating value (HHV) for various feed gas compositions. As can be seen from this correlation results, the quantity of inerts in the feed gas has an impact on the ethane recovery level which can be targeted in a plant design. A simple correlation is also developed here to estimate the propane and butanes recovery percent as a function of ethane recovery percent. The tool developed in this study can be of immense practical value for petroleum and gas engineers to have a quick check of the heat content of the residue gas after recovery of ethane and heavier components from natural gas at various conditions without opting for any experimental trials. In particular, engineers would find the approach to be user-friendly with transparent calculations involving no complex expressions.
3D Pore Space Characterization for Classification of Flow Properties of Reservoir Rocks
Authors: Otiede D. O , Wu K , Olafuyi O. A 
Published: August 2012

Abstract
A method of obtaining petrophysical and single- and multi-phase properties of reservoir rocks without the use of Special Core Analysis techniques is presented. The approached involved three-dimensional image reconstruction from 2-D images of reservoir rocks obtained by micro-computer tomography. Two rock samples were used for the study, namely, a Carbonate-28 rock sample and a Castlegate sandstone. The Carbonate-28 sample was studied at two different resolutions of 1.33 microns and 0.133 microns; while the Castlegate sandstone was investigated at a resolution of 5.6 microns. Network models were extracted from the pore architecture models (PAMs) obtained from the 3-D image reconstruction. The geometrical and topological properties of the extracted networks were then studied; this was followed by numerical flow simulation to derive the single- and multi-phase properties of the rocks studied. The geometrical and topological characteristics of the reconstructed pore architecture models were analysed with the aid of a pore analysis software tool (PAT). The main geometry and topological – characteristics studied included the pore size distribution, pore shape factor, and pore connectivity (in terms of coordination number and specific Euler number). Single- and multi-phase flow properties, namely: average porosity, absolute permeability, relative permeability, and capillary pressure, were measured for all three structures. Results obtained showed that pore size connectivity, and pore size distribution had the greatest impact on flow properties. Specifically, it was observed that the larger the interconnected pore sizes, the greater the absolute permeability; whereas observed permeability was low for interconnectedness involving smaller pores, even with high pore connectivity (that is, favorable specific Euler number). These results can be applied in reservoir characterization to generate flow properties for reservoir rocks; which can be utilized in reservoir simulation and reservoir engineering calculations.
Improved Analytical Model for Predicting Field Production Performance in Vertical Multiphase Flow in Pipes using MATLAB: A Case Study…Part II
Authors: Sukubo I. A. , Igboanugo A. C. 
Published: August 2012

Abstract
Several multiphase models exist for predicting pressure drops in vertical, inclined and horizontal wells. Most of these models made efforts to unravel the underlying physics of multiphase fluid flow for both mechanistic and analytical models with ranges of applicability. However, these developed models have their specific limitations or ranges of applicability in terms of pressures, rates, basic sediments and water (BSW), choke sizes, fluid ratios, etc thus there is no one model that is universally acclaimed best.
Data from fifteen (15) wells were obtained from a Nigeria field and multivariate linear regression was fitted into the data resulting in a good fit particularly for high production rates/wells. The method of least squares was adopted which involve setting up a set of normal equations, solving them by Gaussian elimination technique and fitting the data into the normal equations. The solution of the primary matrix was obtained through the use of MATLAB software which gave point estimates of the regression parameters leading to the development of multivariate linear regression model. The Bootstrapping method of statistical inference was also used to estimate the confidence interval of these regression parameters, while the Durbin-Watson test statistic was used to test model adequacy. The results of the model compared favourably with existing models within considered range of applicability.
This paper therefore aims to address the challenges of field based multiphase fluid flow model for operational ease using a set of over one thousand production data sets of about forty (40) years of production taken from a renowned field in the Niger Delta. More specifically, our investigations show that taking the infimum (i.e. lower bound) of the parametric bandwidths of the gas rate, average bean size and the model correction factor, b0 the model predictive capability is drastically improved for low to medium rates.
Best Practices in Seismic Data Processing- A Case Study From Ghana
Authors: Adigwe Helen-Nellie , Shoroye Adeyemi , Ajayi Jumoke , Vasconcelos Rui , Barnett Peter , Elbassiony Ahmed , Matsourak Vira , Masse Michel , Cavalin David , Hussein Waleed , Salah Magdy 
Published: August 2012

Abstract
Today's Exploration seismic data quality requirements for early detailed geophysical reservoir characterization, baseline time-lapse surveys and fluid characterization have been largely satisfied by the technological advances in seismic acquisition. This then followed-up by first pass conventional processing sequence, including inadequate QA/QC and project management renders obsolete the time and effort put into the planning and executing of the seismic survey in the first place, as the processing results will be no better than a conventional exploration shoot, where the main objective typically is coverage and structural definition. This paper deals with experiences from a recent 3D acquisition, first pass processing which was followed by a focussed reprocessing sequence. The latter performed by a multidisciplinary team comprising various levels of expertise from client and contractor. This paper will discuss how the more relevant advances in the application of concepts, models, techniques, workflows and decision processes related to the supervision of seismic data processing, with focus on initial detailed scope definition, contract management plan, team composition and communication protocol, detailed technical meetings and deliverables, QA/QC processes and sign-off, produced a better output in today's seismic processing project..
A Two-Dimensional Reservoir Simulator for Expansion-Drive Reservoirs
Authors: Omosebi A. O. , Igbokoyi A. O. 
Published: August 2012

ABSTRACT
The application of reservoir simulation to mimic the behavior of reservoirs is widely accepted in the petroleum industry. The technique involves planning, constructing and operating a model whose behavior approximates the behavior of the actual (real) reservoir. Often, mathematical equations (i.e., a model) are developed and employed to understand the performance of the real (physical) reservoir. In this paper, a two-dimensional numerical reservoir simulator is developed for expansion-drive reservoirs. Cumulative production at bubble point is computed as a sum of expansion from each cell, based on average reservoir pressure and oil rate from the well. The average reservoir pressure is weighted based on stock tank oil that remains in the reservoir and each cell. Subsequently, plots were generated for average reservoir pressure versus time and cumulative production from each cell versus time. Also, wellbore pressure at mid-horizontal well was plotted against time on Cartesian and semi-log graphs. Furthermore, area plots were generated using color differentiation to illustrate how the reservoir pressure is depleting with time. Simulation studies performed using the developed simulator show a rapid pressure decline as would be expected for an expansion-drive reservoir due to the insignificant compressibilities that typify rocks and liquids. In addition, the reservoir volume estimated from the Cartesian and semi-log plots correctly matched the material balance estimate. Finally, the estimated recovery factor at bubble point (about 2% of the stock tank oil originally in place, STOIIP) agrees with published values in widely-circulated literatures - demonstrating the weakness of rock and liquid expansion as a primary drive mechanism.
The reservoir simulator developed in this work can be used by reservoir engineers to understand depletion in under-saturated oil reservoirs whose primary production is driven by rock and liquid expansion.
Using LWD Tools to Enhance Drilling Operations – A Case Study
Authors: Okoli Ugochukwu , Schrader Hartmut Hans , Foekema Nico 
Published: August 2012

Abstract
Drilling Exploratory and Appraisal wells can be challenging especially when faced with narrow mud weight / formation breakdown gradient windows and the potential for rapid pressure ramps. Operators engaged in the search for, and production of, hydrocarbon reserves in Tertiary basins are frequently confronted with complications associated with over pressured (abnormally high fluid pressure) formations. This is particularly the case in some of the Offshore Assets of Addax Petroleum. The problems associated with these formations are of direct concern to the combined activities of all phases of operations, which include geophysical, drilling, geological and petroleum engineering, thus the knowledge of the pressure distribution of a given area of operations would greatly reduce the magnitude of many of these complexities and in some cases, would completely eliminate them.
This paper presents how the use of the Baker Hughes INTEQ "TesTrak™" tool has been used to measure formation pressures while drilling (before switching off pumps to make connections). On one exploration well, it was observed the well flowed when the pumps were switched off to make a connection, thus indicating the Equivalent Circulating Density (ECD) was providing the overbalance over the formation pressure. It is also important to note that there has been a transition in optimizing the efficiency and functionality of this tool where the the Bottom Hole Assembly (BHAs) have been re-configured with the TesTrak™ being run "upside down" so that the formation pressure measuring probe would be closer to the bit and thus enable the earliest possible formation pressure information, minimizing the likelihood of a pumps off event. The process of automatic cycling of the pumps, which was required to toggle the tool back to drilling mode was minimized (only with full knowledge and agreement of all involved in drilling operations), after it was observed how dangerous it can be loosing the the over-balanced supplied by ECD. To maximize the advantage of having the logging tool read formation pressures real time, the TesTrak™ has been used to take formation pressures to verify prognosed pressure transition zones such that the mud weight can be adjusted to suit the actual pore pressure measured.
The TesTrak™ tool is presently also being used by Addax Petroleum for data gathering while drilling development wells eliminating the need to run wire-line or pipe conveyed logging in highly deviated and horizontal wells. This has saved rig time and drilling operations costs in addition to enhancing drilling efficiency. It has also improved well-site safety, helped optimize decision making and decreased the risk of differential sticking.