bluuebunny/crossref_metadata_2025_split huggingface dataset:
Geomechanical Modeling of a Full Reservoir of the North Sea
Authors: Bourgeois F. , Koutsabeloulis N. 
Published: December 2007

Abstract
A full field study using the geomechanical simulator with a reservoir model was performed to help assess the integrity of the development plan. The study comprised four phases:
Phase I: Enhance the reservoir model. Phase II: Obtain the stress state prior to any operations. Phase III: Perform coupled flow/stress modeling to assess the stress and strain changes induced by production/injection operations up to today. Phase IV: History match the field data using Geomechanics.
Using the graphical pre and post processor VisGen, the reservoir model was extended up to the sea floor. Layers were added on the bottom of the reservoir model to serve as underburden and cells were added on each of the 4 vertical boundaries to serve as the sideburden. Faults and fracture sets were incorporated in the embedded model. The mechanical properties were determined. A stress calibration was determined.
An effective initial stress state was computed that took into account all the complexity of the geomechanical model including contrast in mechanical properties and discontinuity in the rock. The computed initial stress state was in agreement with field data and geological features.
The changes in stress and strain induced by the production/injection operations were assessed using a geomechanical simulator. The computed compaction was in agreement with the estimated value from 4D seismic data. Further, the coupled simulations have demonstrated that compaction and subsidence effects are to be attributed to pore collapse within the reservoir layers and that differential of pore collapse could result in localized well failure.
Finally a coupled fluid flow/stress simulation was performed with dynamic permeability changes according to stress and strain changes. It was established than it was possible to history match the field data based on Geomechanics.
This study demonstrates that geomechanical modeling lends direct support to drilling operations and reservoir management.
Simulation of Vapex Process in Problematic Reservoirs: A Promising Tool Along with Experimental Study
Authors: Rahnema H. , Ghaderi Seyyed M. , Farahani S. 
Published: December 2007

Abstract
Large heavy oil resource presents in reservoirs containing overlying gas cap. However, production from such reservoir is challenging. At the moment there is no proven recovery technique that can be successfully applied to these viscose oil reserves. Recently, vapour extraction process (Vapex) is introduced as an attractive alternative method for such problematic reservoirs.
The objective of this study is to investigate the applicability of Vapex process in reservoirs containing gas cap. This paper is grouped into two parts (i) developing a validated numerical model via experimental data to carry out sensitivity analysis of different parameters which are expensive and difficult to perform on experimental setup (ii) screening study of the Vapex process to real reservoir by using simulation model.
The results show that small gas cap can even be advantageous in this process and improves the recovery by expending the interfacial mass transfer rate and the inter-well communication. In addition, there is a threshold value for the ratio of initial gas to oil volume which beyond that the process loses its efficiency. Moreover, increasing the lateral spacing between the injector and producer is not beneficial in the presence of a small gas cap.
Fluid Flow Properties of Different Carbonate Pore Classes
Authors: Pourmohammadi S. , Hetland S. , Spildo K. , Skauge A. 
Published: December 2007

Abstract
Carbonate reservoirs are usually heterogeneous and may contain rock material from several pore classes. The main pore classes in carbonates are inter- and intraparticle porosity, intercrystalline porosity, mouldic and vuggy material, and also chalk and chalky micro-porosity. The definition of the carbonate pore classes is according to pore structure and petrophysical properties. The proper classification scheme can simplify relationships between carbonate pore types, petrophysical parameters and single phase fluid flow characteristics.
Different petropyhysical parameters such as tortuosity, pore size distribution and dispersivity have been compared for relationship between the petrophysical parameters. A recent pore classification scheme was used to characterize miscible displacement in carbonates with variety of pore types.
Pore system classification for carbonates originated among other from porosity-permeability correlation was found to provide correlations also for other petropyhysical parameters such as pore size distribution, dispersion and tortuosity. These relationships were strongest for pore classes with intergrain porosity.
Characterisation of Vuggy Carbonates
Authors: Vik B. , Djurhuus K. , Spildo K. , Skauge A. 
Published: December 2007

Abstract
Vuggy carbonates are an important pore class for carbonate oil reservoirs. The determination of fluid flow properties like relative permeability from laboratory core floods in not trivial for this heterogeneous type of material. In many cases unusual responses have been observed, showing that several basic assumptions used for the interpretation of laboratory core floods are violated for vuggy material. Since the fluid properties can be attributed to the internal structure of the material it is important to highlight rock characterization. The local vug-matrix heterogeneity and connectivity of vuggs leads also to question about representative elementary volume for petrophysical and fluid flow properties. We focus in this paper on vuggy carbonate rock characterization based on Nuclear Magnetic Resonance (NMR), Micro Computed Tomography (µCT) and Computed Tomography (CT) measurements.
The objectives of the research have been to establish a basis for estimates of fluid flow and oil recovery efficiency in vuggy carbonate rocks.
HWU: An Alternative Approach to Well Repairs/Re-completion in Offshore West Africa–A Case Study With Ghana Saltpond Wells
Authors: Okoronkwo A. , Oham K. , Okoroafor B. , Vhelbherg Ohia P. 
Published: December 2007

Abstract
This paper is a case study of the workover operations initially slated for three Saltpond wells located in the offshore coast of Ghana (Gulf of Guinea). The operation was the first Hydraulic Workover Operation (HWO) offshore West Africa. Hitherto, HWO operations in West Africa (precisely in Nigeria) have been restricted to swamp and land locations for the past five years
Due to the pioneering nature of the project, a lot of challenges were anticipated especially in the area of equipment mobilization, logistics, space management and equipment rig up in an offshore platform. These expectations necessitated a site visit to evaluate prevailing operational conditions on the platform. The information gathered was factored in at the planning stage of the project.
This paper will attempt to review the challenges and cost effectiveness of this project, against the backdrop of utilizing conventional alternatives. It will also highlight the basic facilities required in an offshore platform to make the use of HWU in well repairs/re-completion an alternative and cost saving approach in offshore environments.
Effective and Efficient Management of Niger Delta Conflict: A Precursor to Optimization of Oil and Gas Potentials for Sustainable Development in Nigeria
Authors: Udofia David 
Published: December 2007

Abstract
The lopsided knowledge of conflict by many as being synonymous with war, instability, rancor, hostility, fighting, battle, etc and its associated layman management approaches especially confrontational and avoidance techniques has escalated conflicts in various parts of the world. Consequently, this has deprived majority of the populace from reaping the hidden potentials of conflict.
The Niger Delta region is not exempted from this catastrophe. Ineffective and inefficient management of oil and gas conflicts from 1958 when oil was first discovered in commercial quantity in Oloibiri has escalated conflict from open protest to kidnapping of oil workers. The host and international community are not excluded from these crises due to the importance of ‘black gold’ to man and its spillover effect.
Based on its necessity, and despite negative consequences, Oil multinational companies devised various means for continuous exploration and yet optimizations of its potentials are farfetched due to instability and insecurity in the region.
As apriority, this paper will examine causes, types sources, and roots of conflicts in the region. Equally, contemporary conflict management techniques-third party intervention, joint problem solving etc needed for optimization of oil and gas potentials for sustainable development of Nigeria and mankind in general will operationalized.
An Appraisal of the Global Petroleum Upstream Industry and Its Response to Changes in Crude Oil Prices
Authors: Iledare Omowumi O. 
Published: December 2007

Abstract
This paper presents an appraisal of the global upstream petroleum industry and its responsiveness to changes in crude oil prices from 1980-2006. Temporal and spatial analysis of E&P operational performance indicators suggests that the current estimated worldwide remaining reserves can sustain current worldwide production rate for at least the next four decades, ceteris paribus. Further, the study shows that for every one dollar drop in real crude oil price, 64 drilling rigs were disengaged, on average, from drilling activity globally from 1980-1989; and 50 of these 64 were disengaged in North America. Further, for every one dollar rise in real oil prices from 19992006, 24 and 29 new rigs were engaged in North America and worldwide, respectively. The study shows that global exploration activity responds asymmetrically to rising and declining real oil prices from 1980-2006. The study also shows that the impact of oil prices on global production has significant spatial and intertemporal differences as well.
Use of Thermal Insulation to Prevent Hydrate and Paraffin Wax Deposition
Authors: Owodunni O. L. , Ajienka J. A. 
Published: December 2007

Abstract
Hydrates and paraffin wax deposition are major flow assurance issues of concern in oil and gas production particularly in offshore operations. Thermal insulation is an attractive measure for preventing hydrate and wax deposition.
In this study, a simplified Microsoft Excel Based program was developed for evaluating the effectiveness of thermal insulation in preventing deposition within the tubing when various insulating materials are placed in the tubing-casing annulus as replacement for completion brine. The effects of flowrate and tubing size were also analyzed. The study was performed by modeling steady state and transient heat transfer within the production tubing for both producing and shut-down conditions.
Comparatively, most of the insulation systems considered gave better performance than completion brine. This effect was more significant at low flowrates. It was found that the most effective insulating materials for preventing heat loss and solid deposition during flow conditions do not necessarily possess good insulation characteristics in shut down conditions.
Incorporation of flow assurance issues during completion design can have great impact in reducing incidence of hydrates and paraffin wax deposits.
New Model for Sizing FPSO Vessels Determines Product Availability
Authors: Jones Ogwo Obike Ume , Mbeledogu Ikechukwu Uduezue 
Published: December 2007

Abstract
Deepwater operation and economic constraints demand optimal sizing of Floating Production Storage and Offloading (FPSO) vessels, especially in a hydrocarbon terminalling facility unitisation arrangement where production space economy is critical to operations. A new multi-parameter model is presented for optimal sizing of FPSOs. In the development of the model, a semi-mechanistic approach is used. The model meant for the determination of the optimum gross hull capacity of the FPSO is also applicable to storage tanks in land terminals. A comparative analysis of the existing model and the proposed one is presented. It is shown that the new model has extra capability to explicitly determine product availability under different operating scenarios.

Introduction
Presently, a 2-parameter model in which production space implicitly depends on gross production rate and offtake tanker traffic is available for sizing oil storage terminals. Nevertheless, in a unitized hydrocarbon terminalling facility, optimal tanker size depends principally on how much oil can be made within a loading cycle. Two (2) fields could have the same gross production rate and offtake tanker traffic but different net oil production rate, the rate difference arising from difference in product quality - fluid density and water content. Water draining capability also determines how much oil is available per unit time.
The storage capacity of an FPSO sized based only on gross production and offtake tanker traffic can be significantly less compared with the capacity of the same vessel established with some other design parameters considered, such as drainage facility, number and size of storage compartments, etc. The corrolary is that two vessels of the same deadweight rating and hire-rate could have different storage capacities depending on design parameters. Thus, tanker sizing without reference to product quality and treatment problem would lead to under-/over- sizing of FPSOs or land terminals. Over-estimating the required vessel capacity tends to discourage unitisation of hydrocarbon terminalling facilities because of the limited availability of such large capacity vessels.
This paper presents a new terminal sizing model that considers additional constraints, including fluid properties and dynamics, treatment problems and vessel structural outlay.
Pressure Measurement and Pressure Gradient Analysis: How Reliable for Determining Fluid Density and Compositional Gradients?
Authors: Jackson R. R. , Carnegie A. , Dubost F. X. 
Published: December 2007

Abstract
Pressure-depth plots have been used for over thirty years to evaluate fluid density, fluid contacts, and pressure compartmentalization in formation tester pressure surveys. However in the Niger Delta region and other offshore deepwater environments, many reservoirs are multilayered and highly variable in terms of connectivity, permeability and fluid properties. Such complexity and reservoir heterogeneity means conventional pressure-depth plot and pressure gradient analysis of wireline pressure data is not easy, and identification of in-situ fluid type can be difficult. There is also mounting evidence for the presence of compositional gradients in the hydrocarbon columns of some reservoirs – this raises questions about the conventional approach to pressure gradient analysis and uncertainties in inferring fluid properties and contacts from pressure gradients.
In this contribution using several field examples, we discuss and review formation pressure measurement techniques and data quality, and compare conventional and advanced methods of pressure gradient analysis and fluid contact determination. The interpretation techniques compared include traditional pressure-depth graphical methods, the excess-pressure method and statistical tests. Depth dependent fluid property variation from fluid gradients, PVT properties and EOS-models are compared and discussed. Guidelines are presented on how to interpret wireline pressure measurements in multilayered siliclastic reservoirs, perform connectivity and compositional gradient assessment. We describe how to improve on these interpretations by performing more advanced formation testing procedures; some of which are based upon new and emerging technology.
Using Phased Development as Reservoir Management Technique To Improve Efficiency and Reduce Operational Cost: Ogbotobo Case History
Authors: Ikponmwosa Abu 
Published: December 2007

Abstract
The search for optimal development of a field involves proper knowledge and implementation of Reservoir management techniques. Drawing from the experiences of brown fields in the Southern swamp area, various techniques were identified to optimize the value of a project, aimed at further development of the field; these include phased development, focus on areas of highest potential, implementation of reservoir surveillance, accelerated production, lower operating cost, etc.
Reservoir management is an ongoing continuous cradle-to-grave process, which targets depletion of reservoirs in a way that maximizes recovery and return on investment.
Hydrocarbon was encountered in the Ogbotobo field, between depths of 4755 (X sand) to 8684 (Z sand) ft tvss; however, the major reservoir is the Y (OWCs Ca. 5500 - 5821 ft tvss), which accounts for over 75% of the total field STOIIP.
Production commenced from Ogbotobo in 1998 and to date various drilling campaigns have been carried out to optimize development of the field. So far 14 wells have been drilled in the field, while infill drilling is expected to commence in 2010.
This paper will present how phased development aspect of reservoir management techniques have been applied to maximizing the value of the Ogbotobo field.
The development strategy also include the implementation of an early "production/drilling appraisal" campaign also known as the "parallel engineering" philosophy, where production runs parallel with the design of the permanent facilities, thus improving the economic of the project.
Realising Maximum Value From Closed-in Wells in the Northern Swamp Area of SPDC
Authors: Adenuga O. A. , De Wit A. , Tunde T. O. , Oton E. U. , Ayeni O. , Ofili O. 
Published: December 2007

Abstract
A review of closed-in wells in the Northern Swamp Area (NSA) of The Shell Petroleum Development Company of Nigeria Ltd (SPDC) in 2003 revealed huge opportunities in closed in wells that can be realised at relatively low costs through the application of new technologies. Initial estimates of these opportunities in the Northern Swamp Area (NSA) were about 174 intervals with potential gains of some 53 Mbopd (unrisked) and costs of circa $27 million. A detailed review of these notional candidates was carried out by a multi-disciplinary team. The technically feasible and economically viable rigless (non-rig related) opportunities were matured for execution in 2004. This paper presents results of the rigless activities matured and executed in 2004.
From December 2003 to November 2004, 67 jobs were executed with actual total gains in potential of 44,889 bopd against 34,869 bopd planned. Annual average gains of 20Mbopd were realized from these activities against a plan of 14Mbopd. The jobs were executed at F$13.6 million, and Unit Technical Cost (UTC) of $2.07 per barrel. This project has a Net Present Value (NPV) of F$112 million.
A number of new technologies and cost savings initiatives were implemented during the execution of these activities.
A Unified Model for Diffusion Coefficient Prediction in Non-Ideal Petroleum Fluids
Authors: Leahy-Dios A. , Firoozabadi A. 
Published: December 2007

Abstract
Multicomponent diffusion is important in a variety of applications, including improved oil recovery from CO2 injection in fractured reservoirs, solvent injection in heavy oil reservoirs, and flowline deposition. In order to calculate diffusion flux, molecular diffusion coefficients are required, where fluid non-ideality and the multicomponent nature of the mixture have a significant effect. In this work, we will present a unified model for the calculation of diffusion coefficients of gas and liquid states of multicomponent petroleum fluids. We propose a new model for the binary infinite dilution diffusion coefficients. The generalized Vignes relation is used in multicomponent mixtures. The non-ideality is rigorously described by the fugacity derivatives evaluated by the volume-translated Peng-Robinson equation of state. Predictions for highly non-ideal gas and liquid multicomponent mixtures demonstrate the reliability of the proposed methodology.
Using Production History to Identify Acid Stimulation Candidates in the Spraberry Trend
Authors: Coulthard S. A. 
Published: December 2007

Abstract
There are currently over 10,000 wells producing in the Spraberry field of West Texas. A substantial problem in the maturing field is scale buildup on perforations created by poor reservoir water quality. Spraberry operators matrix acidize wells to remove this buildup and increase production. However, operators lack a proactive method to determine acid stimulation candidates. Currently, wells are not stimulated until scale buildup causes flow to cease entirely. Through the analysis of 32 acidized wells in the Spraberry Driver Unit, this paper defines a stimulation screening method that can proactively increase production in the field. The new production criteria specify that strong stimulation candidates are wells that have produced over 17 BOPD in their history and subsequently have shown sharp production decline rates. Stimulating a well that exhibits these criteria increases the oil production rate by an average of 94%. If only 1% of the 10,000 wells in the Spraberry were acidized, an additional 1.5 MMBbl of oil and $85 million in gross revenue could be recovered.
Neural networks can enhance fuzzy corrosion modeling
Authors: Hajizadeh Yasin 
Published: December 2007

Abstract
Corrosion in the petroleum industry is one the major concerns of the managers and engineers. Both upstream and downstream parts face this problem and the companies spend billions of dollars in this area. To remain competitive with the world market and lead the field, this cost must be kept to a minimum. Therefore there is a high demand for a reliable corrosion prediction model, which could assist our decision making. Deterioration modeling is an essential element for both design and operation of oil and gas systems and will increase the life productivity of company assets
On the other hand in many engineering problems the available information is vague and sometimes measured data or expert knowledge is too imprecise to justify the use of numbers. Fuzzy logic is a good solution here and helps us to compute with words. However the problem is that you can not train the fuzzy systems, so neural networks may be useful here to add learning capability to fuzzy systems.
In this paper the problem of corrosion modeling will be discussed using hybrid neurofuzzy approach. Teaching the fuzzy system with neural networks, and using pressure, temperature, oil and gas production rate, CO2 and H2 S mole percentages of the stream as the model inputs and the corrosion rate as the output, 3-D surfaces for the corrosion rate were obtained and the prediction results of the model which is based on the pattern recognition between input and output parameters is tested. These graphs can be used as a reliable tool in corrosion prediction by managers and engineers.
Application of Nonlinear Dynamics Methods to Study of Relationship Between Seismic Emission and Change of Pore Pressure
Authors: Viktorovich Novikov Alexey 
Published: December 2007

Abstract
In this paper it is proposed to apply methods of nonlinear dynamics to analyzing of microseismic emission data. A porous medium saturated with fluid is considered as multivariate automodel system. The process of microseismic emission is simulated in laboratory conditions and acoustic emission data are obtained from a laboratory experiment. These data are used to establish the fact of attractor existence in the phase space and to calculate correlated attractor dimensions. As a result the deterministic nature of acoustic emission process is established and the number of essential variables describing the system on the asymptotic stage is determined.