bluuebunny/crossref_metadata_2025 huggingface dataset:
Maximizing Profitability and Production Availability through Application of the Principles of the Medium-Term Integrated Activity Planning (MT-IAP)
Authors: Bello Halim , Onabanjo Tajudeen , Godswill Chiorlu , Linda Dennar
Published: July 2011

A smart and robust business plan with clear business goals underpinned by the activity building blocks and the resources to deliver the goals, is recognized as a key requirement for a successful business. In a challenging operating environment like the Niger-Delta however, realizing the business goals requires more than just a good business plan. There are many external factors that could potentially impact the premise upon which the business plan was defined. Some of these include funding, host communities agitation, criminal activities and even local legislations. With the uncertainties that could be posed by any or combination of some of these factors, a process that provides means of re-calibrating the business plan with the new realities to continuously get an early view of the short to medium term impact of the changes is required. In SPDC the Medium-Term IAP process has been deployed to fulfill this need. Additionally the process deploys the Shell global IAP philosophy to drive delivery of the planned activities in an integrated manner, exploring and implementing scope for activities alignment and also checking that resources required for execution of planned activities are sourced timely. This way activities are executed as planned thereby reducing the risk of cost escalations. They are also executed in an integrated manner thereby minimizing shutdown periods and hence production deferment. It also results in cost savings and reduced HSE exposure. This paper describes how this process is implemented in SPDC and highlights some benefits that have been derived from it.
Mitigating the impact of Down-Hole Shut-in Tool Failure on Gas Well Test Data Integrity: UGO -1X Case Study
Authors: Arochukwu EC , Kehinde DA , Aronu GC , Sa'ad Abdul-Wahab
Published: July 2011

This work demonstrates the usefulness of data quality checks for the purpose of achieving test objectives with an example from a Niger Delta well. The well UGO-1X was completed as single-zone single string (SSS) configuration with a 4-1/2 inch, 12.75 ppf, 13Cr HCS production tubing. The well was tested in order to characterize the reservoir, determine the completion efficiency and ascertain reservoir limit for GIIP estimation. The test program involved multirate production, followed by a build-up phase for which a Down-Hole-Shut-In-Tool (DHSIT) was deployed to manage wellbore storage effects. However with the conclusion of the multirate test, and commencement of build up, the downhole shut in tool (DHSIT) failed and subsequently the well was shut-in at the surface and the build up (BU) stage allowed to progress as per programme.

Following the conclusion of UGO-1X multi-rate test (MRT drawdown and build up), the data was retrieved from the quartz gauges, quality checked and analysed using the conventional and numerical simulation methods.

This paper illustrates the difficulty of interpreting an incomplete set of data, the importance of properly understanding the operational history in well test analysis as well as the usefulness of conducting a quick analysis to validate data thereby avoiding a repeat operation. It is shown that by careful reprocessing of the data (de-listing data within the DHSIT failure interval), the overall quality of the data could be significantly improved and used to produce credible results. This made it unnecessary to conduct a repeat of the MRT/BU on UGO-1X as initial test objectives were achieved.
Modeling and Numerical Analysis of Mud Filtration for a Well with a Finite-Conductivity Vertical Fracture: Based on Convection-Dispersion Filtrate Transport
Authors: Pordel Shahri M. , Mosleh Tehrani M , Namvar M.
Published: July 2011

Most of the drilled wells are conducted on acidizing in order to eliminate the permeability reduction due to mud filtration. This type of formation damage is more sever in naturally fractured wells due to the high conductivity of fracture. If the radius of the damage due to lost circulation of drilling fluid is determined, the volume of acid needed to conduct any acid job could be calculated. Also, prediction of the near-wellbore conditions, such as mud filtrate radius, is important for accurate interpretation of the well-logs used for measuring and monitoring the properties of the near-wellbore formations. In this paper a mathematical model is developed to investigate the amount of mud filtration during drilling operation in a well with a finite conductivity vertical fracture in an infinite slab reservoir. Convection-dispersion filtrate transport model is developed in which the drilling mud can be mixed with the formation fluid. A systematic step-by-step procedure illustrating the methodology of the proposed model for the analysis of mud filtration in a finite conductivity fractured well is presented. This model is formulated for linear flow in both fracture and matrix. The effect of the filter cake is simulated by means of an empirically decaying filter rate equation. The developed model is solved by numerical analysis. The consistency of the numerical solution is checked and the best situation is considered. The sensitive analysis has been done on all the parameters of the model and the effect of each parameter such as wellbore pressure, fracture permeability, fracture diffusion coefficient, matrix permeability, matrix diffusion coefficient, matrix porosity, viscosity, constants related to the filter cake formation and fracture width on the amount of filtration are investigated. By means of the proposed model, the mud filtration can be plotted against position in both fracture and matrix for different wellbore and reservoir properties. The position in the fracture and matrix at which the curve of concentration reaches zero could be considered to represent skin radius. This radius could be used for the determination of the acid volume which is needed for the acidizing operation. Also, this model is a useful tool for accurate interpretation of the resistivity profiles which are essential for the development of efficient well-log interpretation.
Modeling of Meter Factors for Effective Oil Accounting during Proving and Calibration of On-line Meters in Custody Transfer Units
Authors: Bassey Akong , Dosunmu Adewale , Amiebibama Joseph , Agbor Etta
Published: July 2011

Oil metering is the determination of the quality and quantity of well effluent produced, transferred, delivered or sold. This volume of oil must be measured accurately since it determines the amount paid for oil and gas transaction, royalties and taxes. Measurement of oil and gas, purchases and deliveries is made on a flowing well effluent stream. Hence, flow measurement is paramount in the oil and gas industry. Engineers always check to ensure that the well effluent production rate corresponds with a good reservoir management by flowing the oil and gas well through a choke size that would prevent gas cuspling; this is usually done by monitoring the hydrocarbon well stream flow rate at the flow station after well stream fluid separation. To ensure that the volumetric and flow rate readings obtained from meters are accurate and do not impact negatively on the overall economics and operation of a company, meters have to be proved regularly. This is a procedure required to determine the relationship between the true volumes of well effluent measured by a meter and the volume indicated by the meter. For example an error of only 1.0 % in the measurement of well effluent in a pipeline delivering 300MMcfd of gas and 400 barrels of oil at $1million per year can lead to many losses to either the seller or to the purchaser. Therefore, this study is aimed at modeling a meter factor for proving and calibration of on-line meters. . The developed meter factor model will enhance effective meter factor computation to compensate for temperature, pressure and volume of well effluent and steel in custody transfer units(CTU) based on API standard. inaccurate measurement of well effluent will exposed a company not only to the risk of large financial losses, but also manpower constraints.
Monetizing Stranded Reserves: The Role of Floating LNG
Authors: Nwaoha Chikezie
Published: July 2011

As the world's population grows and economies develop, the demand for energy will continue to grow significantly. This increased demand is also being underpinned by the desire for cleaner source of energy to minimize impact on the environment. The International Energy Agency and many others predict that the world's total energy demand will grow by about 35% in 2030 from today's level. Crude Oil and Natural gas are estimated to account for nearly 60% of total energy supply through 2030 for a number of reasons. The growing attractiveness of global Natural gas development also supports the general consensus and forecast that Natural gas will overtake oil towards the middle of the century as a primary energy source. Natural gas is also being used in a variety of processes as feedstock, fuel, etc. Its contribution to world energy resources is growing leading to the concept that it is a bridge to the ultimate hydrogen economy. The flexibility brought about by growing importance of liquefied natural gas, LNG, is also changing the dynamics of the natural gas supply and demand equilibrium. The massive growth in global LNG demand and the challenging supply constraints are putting pressure on the industry to think of more innovative ways to harness and monetize stranded gas fields in a cost-effective and creative manner. Some schools of thought believe that as much as 40% or more of the total global gas reserves is stranded and needs to be brought to market creatively. Such stranded gas resources, found in deep offshore acreages and such remote locations are typically isolated from onshore processing facilities and may not be profitably developed by conventional means. This creates the niche application for the Floating LNG technology as creative way of monetizing the resources. The majority of the world's stranded gas reserves are located in the CIS (30%) and the Middle East (25%). Africa was third, with 16% of the reserves, and was followed by the Far East (13%), Latin America (13%), Alaska (5%) and Australasia (3%). The top-five countries for stranded gas are Russia, Iran, Nigeria, Saudi Arabia, and the Alaskan North Slope in the U.S (http://energy.ihs.com/NR/rdonlyres/8A35BF8A-0CD3-4A13-9E26 1BB5B977C97E/0/stranded_gas_economics.pdf). This paper seeks to identify and emphasize the role and contribution of floating LNG as a more effective way of having access to and monetizing stranded reserves and associated gas, in an environmentally responsible manner safely. This paper also reviews the current status of FLNG projects, to highlight the technical and commercial obstacles that still confront them, and offer insight into how these obstacles might be overcome.
New Method of Generating Approximation Profile of Highly Noisy Wireline Logs through Utilizing Wavelet Non-Parametric Regression
Authors: Shahvar M. B. , Kharrat R. , Dashtbesh Badounak N.
Published: July 2011

Although highly advanced technologies and instruments provide different types of wireline logs data in an oil field today, geologists and petrophysists are faced with the problem of interpreting highly noisy large datasets. In order not to waste the high expenses spent for applying new technologies, effective de-noising techniques are required to lead to the exact interpretation of the data. In the following study that utilizes wireline logs datasets containing more than 30000 data points of an oil field in Iran, new approach of approximating general trend of the data concealed in a heavy noise against depth is applied. In this new method at first the whole profile of the data and their associated depths are transformed as a two vector matrix to a time-scale space of discrete wavelet domain. By reducing the general regression problem to a fixed-design model, decomposing the signal, reconstructing the function that exists between the two vectors and finally re-scaling the resulting function, wavelet provides the general trend of the profile which is thoroughly free of noise and have all the critical information remained within. This advanced technique of reconstructing the wireline log profile is useful where numbers of the data points are large or the signal is heavily overlaid by noises. In addition to logs data, other signals such as seismic traces can be analyzed using this approach too.
Oil Exploitation, Local Economy and Conflict in the Oil-Bearing Areas of Nigeria's Niger Delta
Authors: Babatunde Abosede Omowumi
Published: July 2011

Half of the world's mineral dependent states are concentrated in Sub-Sahara Africa. However, these countries lie at the lowest rank in comparative statistics on human development. Some African countries, for example, Botswana and South Africa, have shown ample evidence that mineral wealth can be turned into concrete development benefit if properly managed. Nigeria, sub-Sahara Africa's largest oil producer is a classic illustration of natural resources as a developmental trap. Oil wealth enriches Nigeria as a country, but it also aggravates the poverty and deprivation in the oil-bearing areas of the Niger Delta. Oil-bearing areas have been facing social and ecological risks which culminated in the violence that have characterized the region. Literature has highlighted the consequences of oil exploitation such as violent communal crisis, youth restiveness, government and oil-companies’ brutal repression. However, the actual nature of the effect of oil exploitation on the local economy has not been established. Thus, this study examines the impact of oil exploitation on the local economy and conflict in the oil-bearing areas of the Nigeria's Niger Delta. This study made use of qualitative data obtained through in-depth interviews with key informants and Focus Group Discussion (FGD). Oil-related activities have affected the people's livelihoods, food security, personal security, physical and mental health. Oil exploitation through environmental degradation depleted fishing and farming output, resulting in the subsequent loss of income base, thereby accentuating poverty, which in turn created divisive tendencies leading to endemic social conflict. Any effort to eradicate poverty in the oil-bearing areas must seek to revive and revitalize the traditional economic activities. Providing viable employment opportunities for the people, particularly the youth, and channelling their energies into the development of sustained livelihoods as well as natural resource management activities can reduce current tensions and conflict in the oil-bearing areas of the Niger Delta, Nigeria.
Option for Adoption of Hydrogen or Natural Gas With Emulsified Biodiesel for Pilot Injection in Dual-Fuel Operation of Diesel Engines
Authors: Bob-Manuel K. D. , Crookes R. J. , Korakianitis T. , Namasivayam A. M.
Published: July 2011

The research on the use of alternative or sustainable fuel in diesel engine operation for transportation and power plant has been intensified in the past few years to achieve improved performance and friendly environment. In this study, an emulsified biodiesel (rapeseed methyl ester – RME) was used for pilot injection in a natural gas and hydrogen dual-fuelled compression ignition (CI) engine to investigate the performance and levels of exhaust emissions under steady state conditions. Generally operation with natural gas dual-fuel using emulsified RME fuel pilot injection reduced NOx emissions while similar operation with hydrogen increases the NOx. The use of hydrogen as fuel in transportation and power plant operation will contribute mainly in the reduction of CO2 and hence greenhouse effect (climate change) on the environment.
Properly Use Effect of Capillary Number on Residual Oil Saturation
Authors: Bashiri A. , Kasiri N.
Published: July 2011

Heterogeneity of the hydrocarbon reservoirs can be defined in pore level or macroscopic scale. Pore level heterogeneity such as pore size and structure controls the quantity of hydrocarbon left (residual saturation) during production, whereas macroscopic heterogeneity determines zones that injected fluid sweeps (Franklin, 1994). During simulation of a reservoir, macroscopic heterogeneity is represented by assigning different rock properties (e.g. permeability and porosity) for different simulation grid blocks. However, due to complex nature of pore entrapment mechanisms, it is only possible to represent pore scale heterogeneity with empirical correlations. Capillary Desaturation Curve (CDC) is a suitable correlation that links residual hydrocarbon saturation to physical properties of a given reservoir in pore scale. Therefore, accurate representation of CDC pattern can be critical for Improved Oil Recovery (IOR) processes evaluation as pore information is used as the basis for residual saturation prediction. Application of CDC data for reservoir simulation and IOR has been reviewed here accordingly.
Properties of Salt Formations Essential for Modeling Instabilities While Drilling
Authors: Omojuwa Emmanuel O. , Osisanya Sameul O. , Ahmed Ramadan
Published: July 2011

Taking drilling beyond the continental shelves further into the great depths of water leaves the drilling industry with no option of avoiding reservoirs lying beneath great masses of salt formations. Presently, salt formations trap rich reservoirs in Brazil, West Africa, Gulf of Mexico, North Sea and off the coasts of eastern Canada. The discovery of producible reserves beneath vast, thick sheets of salt formations challenges the regular drilling and completion practices, making every operation a unique experience. Drilling through salt formations can become successful only when the essential properties of salt formations (e.g. halites) that may cause instability are clearly understood.

Instabilities in salt formations arise from the ability of the salt to flow under loading conditions (creep) and the ability to dissolve at certain conditions and elevated temperatures (solubility). This paper presents the checklist of essential contributing properties that must be accounted for in modeling creep- and solubility-induced instabilities in salt formations. These properties are classified under the physical, mechanical and structural subheadings, and the values of these properties for deepwater subsalt formations are provided for use in creep and solubility predictive models. This paper is based on well design approach i.e. begin the planning from the depth of location of the salt formation, that is, the salt formation becomes the starting point, working backwards to the surface and forward to the target reservoir. Temperature response, melting point, solubility, thermal conductivity, octahedral shear stress, solubility, creep, anisotropy, density, friction, hardness, strength, fracture gradient, permeability are some of the properties analyzed in this paper and their influencing parameters in order to develop an all-encompassing model for used in drilling through alt formations.

In addition, this paper examines the application of the essential properties to the geo-mechanical studies of salt formations. The case study of this research is the design of an exploratory well in the Gulf of Mexico where properties of the salt formations: crystal structures, salt dissolution, creep, temperature and pressure response determined the drilling fluid composition, cement slurry, and casing design.
Reconciling and Improving the Volumetrics of Nigerian Heavy Oil and Bitumen Resources
Authors: Lawal Kazeem A.
Published: July 2011

Despite being penetrated by over 100 wells, and more than a century of studies, the in-place and recoverable volumes of oil resources within Nigeria's bituminous belt are still inconclusive. Noteworthy is the misleading appropriation of "reserves" to the deposit. While there is an obvious motivation to improve the current situation, credibility requires that such efforts are premised on a combination of reliable dataset and robust method of study.

This article is an attempt at reconciling and improving current estimates of the hydrocarbon potentials of the Nigerian bituminous belt. It reviews and integrates numerous datasets on the belt. Reasonable assumptions, empirical correlations and analogue information are used to mitigate identified data gaps while recognising uncertainties. With estimated input data and associated uncertainties, deterministic and probabilistic techniques are employed for robust volumetrics. Unlike previous studies, we consider solution gas.

Using performances of some proven exploitation technologies in provinces of comparable reservoir and fluid characteristics as Nigeria's, we make reasonable estimates of recovery factors, and establish cumulative distribution curves for recoverable (not reserves) volumes of discovered bitumen, heavy oil and oil shale deposits, including the dissolved gas content.

From the analyses, we estimate 71, 207 and 415 billion barrels as the P90, P50 and P10 stock-tank oil in-place volumes, respectively. Corresponding solution-gas quantities are 1.4, 5.0, and 13.6 Tscf, respectively. Compared to current official record of about 43 billion barrels, which does not account for the field-proven solution gas, potentials of Nigeria's bituminous belt may be significantly underestimated at present. Although the volumetric ranges in this study reflect the relative magnitude and impact of uncertainties, sensitivity analysis indicates that reservoir extent and thickness as well as solution gas-oil ratio are the main uncertainties. Consequently, a key objective of future appraisal programs should be to narrow the current range of (static) uncertainties.
Revisit Material Balance Equation for Natually Fractured Reservoirs
Authors: Bashiri A. , Kasiri N.
Published: July 2011

The material balance equation (MBE), as a zero-dimensional model (with some assumption such as uniform pressure, PVT data and temperature within a given reservoir), has been used to identify some critical items such as Original Hydrocarbon in Place (OHIP), relative volume of initial gas cap, aquifer behavior and different depletion mechanism indexes within a given reservoir (Pletcher, 2002). Conventional MBE (CMBE) is based on the black oil concept that can limit its use for volatile oil and gas-condensate reservoirs. Furthermore, heterogeneity of the naturally fractured reservoir (NFR) as a dual porosity system can impose some restriction on CMBE application. A modified MBE is proposed here for use in fractured or gas-condensate reservoirs with some example for its application.
Sedimentary Controls on Porosity and Permeability in Deepwater Turbidites
Authors: Njoku Chukwueke , Pirmez Carlos
Published: July 2011

Knowledge of the sedimentary controls on porosity and permeability is important in the exploration and production of oil and gas in various depositional settings. In deepwater reservoirs this is even more important because of the high cost of development wells. Few studies of porosity and permeability in deepwater reservoirs are available. We report on the main controls on porosity and permeability of deepwater reservoirs using core plug samples from several wells in Shell's deepwater portfolio. Results show that grain size control on permeability and sorting control on porosity and permeability are well reflected in the turbidite and debrite facies.
Simulation of CO2 Enhanced Oil Recovery in Heterogeneous Models
Authors: Biu Victor T.
Published: July 2011

In mature and depleted oil field, it has been discovered that significant amount of oil is left unswept. The ability to evaluate the remaining oil depends on the understanding of the heterogeneity of the reservoir most especially when there is plan for tertiary flooding such as Carbon dioxide EOR

This work focuses on the impact of geological structure on the sweep efficiency and reservoir oil recovery in a small-scale heterogeneous model using CO2 injection. Three models which include; homogeneous, layer and laminated reservoir models with sedimentary structures were simulated with ten hydrocarbon fluid component.

Results from the simulation of the three geological models indicate channeling effect in a laminated model which results to more oil been trapped in the low permeability laminae, thus lower oil recovery. It was discovered that the CO2 rich oil zone forms a mobile displacement front in the 2-D x-y model that enhances the sweep efficiency in all layer and homogeneous models review. At reservoir pressure below saturated pressure, increase in oil saturation close to the injector was noticed in the homogeneous model due to gravitational effect. This could be attributed to the increase in density of the dissolved CO2 in oil resulting to bypassed oil. Result also discovered that higher temperature and pressure, irrespective of the nature of the reservoir system has significant effect on oil recovery during CO2 flooding.
Specific Heat Capacity of Natural Gas; Expressed as a Function of Its Specific gravity and Temperature
Authors: Adewale Kareem Lateef , James Omeke
Published: July 2011

Natural gas engineering entails production, processing, storage and transportation of natural gas. A good handling of the gas requires a sophisticated understanding of how its density, compressibility, pseudo-pressure, and specific heat capacity varies with the gas condition. While petroleum & gas journals and a host of scholastic materials have presented varieties of means to evaluate other properties, they neglected or underscored the need for same for specific heat capacity of natural gas. The only available mathematical relation for this property only predicts its value at 1500F- not at other temperatures.

Samples of natural gas collected from Bell field, Sabine field, Bacon lime and paradox formation were used as data source. The variation of the respective specific heat capacity of the components and the effect of the composition on the specific gravity and overall specific heat capacity of the gas was taken into consideration giving rise to a robust correlation that reads in the individual composition of the gas, its density and temperature to generate the specific heat capacity of the gas.

The result yielded 98.3% accurate result compared to the method of isentropic coefficient at 150°F and an average error of 0.3% within a range of 491°R to 2740°R.

The benefit of this work is that it provides a means of dealing with situation where the heat transferred into or out of a natural gas system is to be calculated over a wide range of temperature as it allows the specific heat to be expressed as an integratable function of temperature other than the isentropic coefficient method which only gives a constant value for a variable that is not constant.
The Crux of the Matter in Achieving a Stable Niger Delta – A Case Study
Authors: Ike I. A.
Published: July 2011

Petroleum production is the most important economic activity in Nigeria, yielding substantial returns to the government, corporate entities and individuals both locally and internationally. It is a truism that the industry would have been able to yield more to all concern but for the prevalent social unrest. To address this issue, government and operating firms in recent times have taken some pragmatic and impressive steps. The government's amnesty program stands tall in this regard. On the part of some firms, crisis management and social responsibility have been accorded so much importance that, for example, they are now handled under a separate and specific department with a direct representation at the board.

The problem in the Niger Delta cannot be said to be over at the moment even with the aforementioned positive developments. To hope for a complete and a lasting solution, the efforts of the key players must take particular cognizance of the social structure. From personal experience in the course of the national youth service in a typical Niger Delta community, this writer believes that the bane of development in the Niger Delta and consequently the cause of its instability is the failure of formal and informal education to meet the challenge of the society which is manifested in crippling truancy as a result of student's involvement in economic activities at the expense of formal education, formidable organized examination malpractices, obnoxious students' indiscipline and teenage pregnancy. The writer charts a solution path that is practical and focused on correcting the fundamental social ills as a sure means of stabilizing and developing the region while enhancing the activities of the oil industry.
The Impact of Sand Control Techniques on the Efficiency of Horizontal Wells
Authors: Joseph A. , Arinze U. , Ajienka J. A , Ikeh L
Published: July 2011

The production of formation sand into a well is one of the oldest problems plaguing the oil and gas industry. This is because of its adverse effects on the well productivity and equipment. In order to ensure safe operation of facilities, reduce formation damage and enhance productivity, operators spend millions of dollars on sand control techniques. Some of the most common sand exclusion techniques used for horizontal completions in Niger Delta include: the open-hole gravel pack (OHGP), stand-alone screens (SAS) and expandable sand screen (ESS).

This work involves a comparative analysis of the different horizontal sand exclusion techniques. In this work, evaluating the impact of sand control techniques on the production performance in horizontal wells is evaluated. Some performance indicator tools such as the well inflow quality indicator (WIQI), performance efficiency, completion efficiency, quantity of sand produced and the production decline rate after installation of the sand control technique was used to compare the flow performance of wells equipped with these sand control techniques. The analysis involves the use of analytical models and software using the principle of nodal analysis. For the Nodal analysis, the effect of skin, reservoir pressure, gravel pack length and gravel pack permeability was investigated on the performance of the gravel pack and stand-alone screen completions techniques only. The results showed that, the expandable sand screen proved to be a better sand exclusion technique in terms of performance followed by stand-alone screens and then the open-hole gravel pack.
The Strategic Aggregator and Securitization of Gas Sales Agreements – The Nigerian Experience
Authors: Odizuru-Abangwu I. N , Okoronkwo V. I.
Published: July 2011

One of the many challenges facing the energy sector in Nigeria is the lack of securitization of the Gas Sales and Purchase agreements (GSPA). Simply put, the GSPA's are non-bankable and do not have any offtake or payment guarantees (even without Take or Pay clauses, the contracts can still be enforceable in law)

Given the role of gas in the Nigerian energy mix, this becomes an important issue that must be addressed for future viability of the gas sector. Gas, unlike oil as a commodity, cannot be stored for a long time after production and hence requires long-term gas supply commitments with off take and payments guarantees to be able to secure financing and make the investment decisions.

One aspect of securitization of the gas commercial agreements is the use of Take or Pay clauses to ensure revenue flow to the suppliers. This ensures long-term commitment on both the suppliers and buyers' sides and hence, provides the basis for investment decisions.

The other aspect is the use of either Sovereign Guarantees or Partial Risk Guarantees granted by the World Bank to ensure project viability. l The PRG scheme which basically ensures that GSPA's are backed by credible instruments backstopped by the World Bank.. This article analyzes this scheme and its role in the securitization of gas agreements in the Nigerian energy industry.
Total Asset Surveillance and Management
Authors: Wokoma E. , Okuns G. , Idachaba F. E. , Edghill P. , Pickburn A. , Ashion O.
Published: July 2011

This paper presents the report of a pipeline intruder detection system using the Optical Time Domain Reflectometry (OTDR) based Distributed Vibration Sensor technology (DVS). A 12 km optic fiber cable was buried under a 0.9m thick slab of concrete buried 1.6m deep along an SPDC 18" pipeline within the pipeline right of way (ROW). The application of the OTDR was to detect some predefined types of intrusion (walking, digging, driving, etc.,) normally associated with vandalism and bunkering activities along the pipeline ROW. The system was able to identify with sufficient signal clarity; the footsteps of a man weighing about 80kg walking up to 3m near the buried sensor, digging activities at about 3m away from the optic fiber cable, a moving herd of cattle crossing the pipeline ROW from 15m to the ROW, the presence of a wheeled 4x4 vehicle 10m away from the buried cable and a 5 ton truck 50m away from the cable was also detected. The results were displayed on a graphical user interface with different colour codes for each intrusion event or category. The system was found to be able to detect the different possible types of intrusion activities prevalent around pipelines. The concrete slab was found to have minimal effect on the sensitivity of the optic fiber with respect to its ability to detect intrusion activities up to 5m from the optic fiber cable, but for areas without the concrete slab, the system sensitivity much better, hence the received intrusion signal strength was found to be very high. This system can be deployed along our pipeline ROW to provide intrusion detection for SPDC pipelines and provide an early warning system for malicious intents on the pipelines.
Effect of Salinity Changes of the Injected Water on Water Flooding Performance In Carbonate Reserviors
Authors: Idowu Jiboku , Somerville Jim , Adebari Deola , Meshioye Oluwafisayo
Published: July 2011

Water flooding is a promising oil recovery mechanism, which has inherent potentials to recover more oil from the reservoir. Quite unfortunately, the mechanism has been under utilized due to improper consideration of quality of water to be injected. The quantity of water injected into the reservoir has always been of interest to the Engineer, until recently when they became interested in the quality. They soon discovered that if proper consideration is given to the quality of the ionic composition of the injected water by lowering its TDS, oil recovery can be greatly enhanced, and residual oil saturation immensely reduced (Tang and Morrow 1999). Its evidences in the literature are undisputable. Lowering the salinity or TDS of injected water results in lowering the oil-rock capillary pressure, reduction in oil-water interfacial tension, and finally a change in the relative permeability, which results into a wettability change, usually to a mixed-wet or water-wet state.

This project aims at determining the impact of low salinity water flooding on oil recovery in a carbonate reservoir in the Middle East. It was decided to use ECLIPSE and an analytical solution as methodologies for solving the problem.

Quite interestingly, ECLIPSE was not able to predict increase in oil recovery due to non- dependence of salt concentration on relative permeability in the model.

The analytical solution predicted an oil recovery of about 9% FOE, with an additional oil volume of three million and seventy-six thousand barrels (3,076,000 STB) to be recovered at the surface.

This increased the worth of the company by one hundred and twenty three million, and sixty-four thousand Dollars ($123,064,000), when a pessimistic oil price of $40/barrel is used.

Indeed, it is a cost effective oil recovery mechanism with little or no investment cost. It is however recommended to inject water in the range of 1500ppm or lower.
Investigation of Fracture Ballooning and Breathing in Naturally Fractured Reservoirs: Effect of Fracture Deformation Law
Authors: Pordel Shahri M. , Zeyghami M. , Majidi R.
Published: July 2011

Borehole ballooning-breathing is the term used to describe reversible mud losses and gains during drilling operations. In naturally fractured reservoirs borehole ballooning-breathing caused by opening/closing of natural fractures is the major mechanism of this phenomenon.

An accurate model of the fracture-induced ballooning-breathing phenomenon could provide an aid in mud optimization and improve the well control procedures while drilling in naturally fractured reservoirs. Using this model, the hydraulic aperture of conductive fractures can also be obtained by continuous monitoring of mud losses and gains. Different models have been developed recently discussing this phenomenon. Each of these models considered some special conditions and investigated the effect of different parameters.

This paper first discusses the previous models of fracture ballooning in detail. Then a new model is developed for radial flow of mud with Yield-Power-Law (Herschel-Bulkley) rheology in a single isolated deformable horizontal circular fracture. In this model exponential deformation law is used for fracture deformation, which is more realistic than the simplified linear deformation law. Also, this model is developed for both fracture ballooning and breathing phenomena.

From the developed model it is concluded that cumulative loss in the case of exponential deformations less than that of linear deformation during fracture ballooning. This difference is due to pressure distribution in both cases. The pressure builds up faster for exponential deformation due to higher transmibility of the fracture. Different conditions are discussed in detail which could help in better understanding of the factors controlling borehole

ballooning-breathing during drilling operation. Shortcomings of the developed modeling approach are outlined.
Production Logging in Open Hole Completions
Authors: Nnoaham Ikechukwu , Anyaehie James , Akam Somadina , Ekeigwe Augustine
Published: July 2011

Production logging was carried out on the well with the dual objectives of determining the producibility of the shaly intervals of the reservoir where the Nuclear Magnetic resonance (NMR) logs showed indications of mobile fluid and to determining the possibility of cross flow across the sub-units of the reservoir. The PLT assembly deployed consisted of spinner, capacitance, temperature and pressure sensors. The spinner readings were used in computing the total flow rates (QT) which were used in the qualitative interpretation of results.

Due to the fact that the well was completed with expandable sand screens as sand control mechanism, it was difficult to qualitatively analyse the temperature and pressure data. However, a qualitative interpretation of the computed total flow rates (QT) indicates that the some subunits, which had better sand quality, were contributing to flow. On the contrary, flow could not be established in the other sand members. The test also revealed that zonal contributions can clearly be established if the well is flown at higher flow rates.

It is recommended that future production logging tests on wells aimed at establishing zonal inflow contributions should be flown at maximum flowrates in order to establish the producibility while tests on wells completed with expandable sand screens aimed at identifying zones of gas inflow using temperature data are strongly not recommended.
Rock Typing and Generalization of Permeability- Porosity Relationship for an Iranian Carbonate Gas Reservoir
Authors: Shabaninejad M. , Bagheripour haghighi M.
Published: July 2011

Reservoir characterization methods are very important as they provide a better description of the storage and flow capacities of a hydrocarbon reservoir; moreover it plays crucial role in reservoir simulation models. Carbonate reservoirs show challenges to engineers and geologists to characterize because of their tendency to be tight and generally heterogeneous due to depositional and diagenetic processes.

Among the various quantitative rock- typing techniques presented in the literature, the hydraulic flow unit method (RQI/FZI) is more widely used. ‘D’ is a main carbonate formation for one of the giant gas reservoir in Iran. In this study, available routine core data from four wells are assembled to develop improved generalized permeability porosity relationship for characterize ‘D’ formation by (HFU) concept.

For this purpose, three wells are considered to develop HFU transforms for ‘D’ formation. Correlation accuracy of each discrete rock type (DRT) was very good (R2>0.9) for horizontal permeability. Then all data from different wells were combined to determine generalized porosity permeability relationship for ‘D’ formation. This transform was tested for its accuracy on available core data of fourth well which exist in the same formation. Calculated permeability data by HFU technique matched very well with the routine core data which confirm the accuracy of generalized HFU transform. In the same manner, generalized vertical permeability relationship was developed for ‘D’ formation and tested for its accuracy
Application of Near Neutral Pickling Fluid in Workover Riser Pickling and Fishing Operation in the Niger Delta: Case Histories
Authors: Oladiipo Abiodun , Mofunlewi Samuel , Bankole Abidemi
Published: July 2011

The many purposes and benefits of tubing pickling include iron control, scale removal, sludge prevention, removal of damaging pipe dope, asphaltene or paraffin deposit, elimination of spent acid, prevention of sulphur species deposition, improvement in stimulation and reduction in overall treatment cost.

Corrosive hydrochloric or acetic acid is the common pickling solution. Additionally they often contain hazardous organic solvent and surfactant to remove asphaltene or wax deposit and pipe damaging dope residue. The major problem of acid based system is safety concern as pickle acid systems are classified as hazardous materials before pickling and upon return to the surface after treatment. The near neutral pickling fluid is an environmentally favourable derusting fluid which has the capability of reacting with rust, mill scale and steel substrate producing a protective phosphate film that coats the metal surface to provide a corrosion protection through passivity mechanisms.

Near neutral pickling fluid has been successfully applied in some workover risers in the Niger Delta at low seabed temperature. Results of the applications are very impressive and these shall be discussed in this paper. Also to be discussed is the application of the near neutral fluid in the fishing of a 2-3/8″PXN plug which got stuck at the XN-nipple in an old tubing making it impossible to set an A-5 dual completion parker. All previous attempts to retrieve the fish for over 72 hours had failed but the fish (23ft long) was recovered with slick line after soaking well with the near neutral fluid over night.
Comparing the Effects of Pipe Diameter on Flow Capacity of CO2 Pipeline
Authors: Ikeh L , Race J. M , Aminu A. G
Published: July 2011

As carbon capture and storage (CCS) is considered as one of the options for reducing atmospheric emissions of CO2 from human activities and the environment, there are needs to examine the role that a pipeline infrastructure for CCS could play in reducing the CO2 emissions, and the possible development of pathways for a CCS pipeline connecting the source with appropriate sink. In the cost estimation of the CO2 transport, the pipeline diameter plays an important role in optimizing the CO2 to enable the storage of several millions of tonnes of CO2 per year. This paper examines the modelling of a straight pipe segment carrying pure CO2 with impurities and evaluate the effects of different pipe diameter on flow capacity using a pipeline hydraulic simulator. PIPESYS is an integrated flow simulator that allows the modelling of a single and multiphase static and dynamic flow for pipeline hydraulics. This is done by maintaining the inlet parameters (Pressure, Temperature, and mass flow rate) and a pressure drop at a range of length. The process includes using the Peng Robinson (PR) Equation of State and the Beggs and Brills-Moody pressure drop correlation to calculate the PVT behaviour and flow regime respectively. Also, artificial neural networks(ANN) using MATLAB was employed to train and verified the data obtained. The results shows that the models can be used effectively to determine and predict the effects of pipe diameter to flow capacity of CO2 pipelines.
Experimental Studies of Sand Production from Unconsolidated Sandstone Niger-Delta Petroleum Reservoir
Authors: Adeyanju O. A , Oyekunle L. O.
Published: July 2011

Sand production from Nigeria's Niger-Delta oil and gas reservoir has been simulated with a physical model. The model can accommodates both unconsolidated and consolidated sandstone cores. The objective was to determine the ability of using the flow rate to control the production of sand. Results show that the sand production is both affected by the flow rates, the confining pressure, the drawdown and the viscosity of the formation fluid.

High sand-free flow rates can be achieved if the sand formation is mechanically confined (compacted). The grain size distribution of the produced sand in the laboratory is identical to that of the field sample. At high confining pressure only small sand sizes are produced from the porous medium. In case of water and light crude oil sand production can be controlled by managing the flow rate while it is impossible to control sand production from heavy crude oil formation by managing the flow rate alone. According to the confining pressure results, shallow formation results in larger sand production than those in deeper wells.
Hydrocarbon and Mineral Exploration Using Thermoluminescence and Cathodoluminescence
Authors: Alimuddin Sultan , Shah Nihar , Gandhi Kanan , Satyam Swapnil
Published: July 2011

This paper relates to the method of exploration for hydrocarbons and minerals in particular by using artificial and natural thermoluminescence and cathodoluminescence analysis methods.

Luminescence is the emission of light from a solid which is excited by some form of energy. Thermoluminescence is the phenomenon of emission of light caused by thermal activation of trapped excess electrons and their corresponding electron deficient sites. Generally quartz, carbonates (calcite and dolomite) and the feldspar groups determine thermoluminescent properties. Here the possibilities of application of artificial Thermoluminescence to determine the proximity of a core sample to a Hydrocarbon reserve are reviewed. The advantages of using thermoluminescence after geophysical exploration is to pinpoint the exact location of Hydrocarbon and Minerals reserve. In Cathodoluminescence the excitation of electrons is achieved by electron beam. Here we see how Cathodoluminescence can be used to know the petro physical properties of the sample, which will in future aid to the knowledge of accurate characterization of reservoir.

Nowadays Geophysical way of exploration is used worldwide. In this process mainly we do seismic surveys and based on their travel time an approximate image of the subsurface is generated. Thermoluminescence and Cathodoluminescence can complement the exploration by geophysical prospecting and can add certainty to locate the zone of interest. Thus more accuracy and precision are achieved by bridging geophysical analysis with logging data. Sensitivity of Thermoluminescence and Cathodoluminescence have also been covered here. Mineral and Hydrocarbon exploration both can be done side by side. Hence it can help link Oil and Gas Company with mineral exploration company and reduce cost of exploration. Thus here we aim to assemble past ideas and invention, current works on the topic in the fields and future scope of the methods proposed here for exploration.