bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Semi-Analytical Post-Breakthrough Predictions for Vertical and Horizontal Wells
Authors: Ike I.A. , Debasmita M.
Published: July 2013

Abstract

Horizontal and vertical wells are commonly used in the production of oil lying above a water zone, or above a gas zone or sandwiched between the gas and the water. Under such conditions, water or gas coning is a very common problem. Experimental, empirical and analytical works have been done in determining the critical oil production rate and the breakthrough time if production is supercritical. Aside from numerical simulations, post-breakthrough production predictions have been restricted to experimental and empirical techniques employing statistical regression.

In this work, employing analytically derived breakthrough time expressions for vertical and horizontal wells, a technique have been developed to semi-analytically predict the rate of oil and water production after cone breakthrough in vertical and horizontal wells. The results of this new procedure were compared with predictions from numerical simulations and some common literature correlations. Though the analytical technique tended to under-predict oil production, it presented a trend which conformed more to the numerical simulation results than the correlations tested. It thus can be used for checking more complex numerical simulations and can serve as a backbone for developing consistent post-breakthrough correlations.

Simplified correlations for the determination of breakthrough time for vertical and horizontal wells were also developed from the semi-analytical formulations. To the best knowledge of the authors, this is the first semi-analytical post-breakthrough modeling of vertical and horizontal wells.

Introduction

Work on coning had generally been pursued along the path of preventing or delaying cone generation and evolution, the time to breakthrough if advancement is not checked and the performance of the well after cone breakthrough. A number of empirical and analytical studies have been conducted to model and determine these properties (Joshi, 1991). Correlations and models for the determination of critical rate of oil production, time to breakthrough when producing at super-critical rate and the performance of the well after breakthrough have been developed for vertical and horizontal wells. These models may be experimental, empirical or analytical. After breakthrough performance model available are generally not analytical.
Development of a Computer Program for Solids Control
Authors: Adjimah M. J.
Published: July 2013

Computer software is used extensively to increase productivity and reduce man-hours of labour. This work presents the development of a simple solids control software (SOLCON) which is designed for real time mud system management and quick performance of routine rig computations: determination of total solids and low gravity solids content; mud property and density control requiring optimal ejection rate into the mixing pit; volume of mud and amount of barite, bentonite and additives to be added during the upgrading process of the mud. This software has the ability to evaluate the need for dilution depending on the maximum allowable drilled solids, viscosity and recommended total solids in the drilling fluid.

In addition, a procedure for determining the actual drilled solids that remains in the drilling fluid after routine solids control using the 200 and 150 mesh size shale shaker has been developed to enhance efficient control of drilled solids.
The Changing Face of Global Oil and Gas Production and its Implication on Nigeria
Authors: Ike I. A. , Leo M.
Published: July 2013

The media are awash with discussions of the US becoming the largest oil producer in less than a decade and to be self-sufficient in energy in about two-decade's time. That means a lot for Nigeria since the US has been the largest buyer of Nigeria's crude oil. Losing one's largest customer only to see the erstwhile customer becoming a major competitor is a dreaded nightmare for any business outfit. India and China may not necessarily have the capacity to buy off what the US is predicted to leave off as there are potentially new players like the countries of East Africa, Brazil and Canada coming on the scene or strengthening their hold on the market. It is also important to note that the shale business may also thrive in China, a country that is estimated to have the largest shale gas reserve. This paper investigates the far-reaching implication of these strategic developments and prospects on the future of oil and gas production in Nigeria and on the Nigerian economy which is currently heavily dependent on petroleum revenue. It concludes that Nigeria can only have a chance if it aggressively increases it local energy utilization and become more competitive in the oil and gas business by improving community integration and environmental responsiveness, transparency, professionalism and efficiency.
Modelling Formation Damage Induced by Propagation of Single-Phase Non-Newtonian Polymer Solution in Porous Media
Authors: Idahosa P. E. , Oluyemi G. F. , Oyeneyin M. B. , Prabhu R.
Published: July 2013

Non-Newtonian high molecular weight polymers dissolve in water to increase viscosity for stable displacement of oil and gas by injected water and enhanced sweep recovery. In both microscopic and macroscopic description of geological factors controlling delivery of oil and gas from reservoir to wellbore, and hence, total eventual production, permeability is a dominant factor. Despite the role of polymers in enhancing oil recovery, polymer adsorption on rock surfaces can also cause permeability reduction, and hence, oil and gas productivity decline due to flow restrictions (formation damage). In the literature, studies on selective permeability reduction (with emphasis on mobility reduction and residual resistance factors) by polymer adsorption based on constant absolute permeability assumption are well known. However, even then, these studies are based on mathematical expressions and formulations that are subjective. There is therefore no existing model that fully considers a combination of the effects of polymer adsorption and its non-Newtonian behaviour on absolute permeability during single-phase propagation in porous media. In order to describe single-phase non-Newtonian flow in porous media, a macroscopic flow rate/pressure drop relationship that combines a mathematical description of fluid rheology must be developed. In this paper, a new method is developed in order to investigate and characterize absolute permeability alteration due to the propagation of single-phase polymer solutions in porous rock media. The validity of the proposed model is demonstrated by using experimental data sets involving single-phase polymer flooding with varying concentrations and formation permeabilites.
Entrepreneurship & Small Business Start-Up
Authors: Efemena Doroh , Monye Benedict
Published: July 2013

For effective growth of Oil & Gas Production in Africa, there is need for workable policies, funding by Government, Agencies and Multinationals, establishment of Oil & Gas Industrial banks and the lowering of lending and interest rates, giving of grants to screened and trained would be entrepreneurs, the collaboration of local entrepreneurs with foreign technological companies, investment in local innovations and technologies, development of similar techniques and software, investment in ICT, training and preparation of employees on entrepreneurship towards retirement and human capital development.

According to Robert T. Kiyosaki, author of Rich Dad Poor Dad, financial struggle is often directly the result of people working all their life for someone else. Many people will have nothing at the end of their working days. Perhaps this attitude, which is also common amongst most African nation citizenry, is a product of colonialism on the colonized generation, but that is not an excuse to continue at it if their economy must improve. Philip Adams once said. Most people can do extraordinary things if they have the confidence or take the risks. Yet most people do not. They sit in front of the internet, television and treat life as if it goes on forever.

Conclusion

Starting and operating one's own business has been becoming an interest area for individuals from different stock of life. Therefore entrepreneurs should acquire desired knowledge, skills, and competencies that would enable them to become confident entrepreneurs who are capable of creating innovative important business ideas. The various governments should also put things in place.
Valuation Of Renewal Bonus For Expired Leases
Authors: Babalola S. A. , Ogunnubi O. B.
Published: July 2013

The determination of Renewal Bonus has been the concern of the Department of Petroleum Resources. Renewal Bonus is the amount to be paid by leaseholders to Government for the renewal of expired leases. The challenge has been which technical criteria should be used for an equitable determination of the bonus to be paid to ensure industry-wide acceptance.

To overcome this concern, an economic model was developed and fine-tuned using already existing fiscal terms. The model was made robust by using actual oil, gas and condensate production data over the life of the block, the company's projection of the performance of the blocks over the next five years that is acceptable for business decision making and its further estimates for fifteen years to cover the twenty year renewal period, assuming its license renewal is approved.

The economic model was run using existing fiscal terms together with the concession's historical OPEX, CAPEX, and annual production. The ultimate recovery and reserves of the fields within the block was also utilised. The model then determined the NPV for liquid (oil and condensate) and gas (Associated and Non Associated Gas) over the twenty-year renewal period. The model was run over the block life covering periods before expiration up to the new twenty-year renewal time and beyond.

Company equity and logically derived Renewal Bonus Constant was used to compute the amount to be paid by the operator. Sensitivities were run on the model to determine the best-case scenario for liquids, gas and BOE (for a combination of liquids and gas) that could enable the DPR management make appropriate, fair and therefore acceptable recommendation to the Honourable Minister of Petroleum Resources (HMPR).

The result of the Renewal Bonus for each company suggested consistency when the plots of Renewal Bonus against the BOE for all the companies were made.

This paper is intended to give insight to the fairness of the DPR in technical decision making that have led to effective advice to government.
Deepwater Nigeria Field Development: Challenges, Best Practices and Lessons Learned from the Agbami Field
Authors: Odusote Femi
Published: July 2013

With potential reserves of about 1 billion barrels of oil, the Agbami Field is one of the largest producing deepwater assets in Nigeria. The field was discovered in 1998 and was put on stream July 28, 2008 at an initial production rate of ~ 95 MBOPD. The field reached peak production of 250 MBOPD on Aug 13, 2009, 4 months ahead of schedule. Agbami is Chevron's first operated deepwater asset in Nigeria and is located 70 miles offshore from the Nigerian coastline at a water depth of about 4,800 feet.

The Agbami subsea development plan consists of 38 subsea wells (22 producers, 11 water injectors and 5 gas injectors) tied back to a Floating Production, Storage, and Offloading (FPSO) vessel via subsea flowlines. The development strategy is to have mid-flank oil production with peripheral water injection and crestal produced gas re injection to enhance recovery from pressure maintenance and improved sweep efficiency in addition to compliance with a "No Flares" policy. The field development plan was optimized to be executed in 3 stages, and is currently in Stage-2 with 14 producers, 3 gas injectors and 6 water injectors already drilled, completed and contributing to the daily production.

2013 will mark 5 years since the Agbami field came on stream. The field has produced about 350 MMSTB of oil as at year end 2012 at a 2012 average rate of 233 MBOPD. The field continues to perform with operational excellence in all areas from safety to production in-spite of the several challenges that are faced on a daily basis. This is as a result of the focus on operational excellence and sound reservoir management practices.

This paper seeks to highlight the performance of the Agbami field to date and demonstrate how a focused reservoir management approach has resulted in the the fields’ world class performance in spite of the challenges faced. The paper will also seek to share best-practices and lessons learned from the Agbami field experience.
Use of High GOR Wells for Artificial Lift in a Mature Field - the OFON Field Case
Authors: Faseemo Oladipo , Odeniyi Akintayo , Onyema Uche
Published: July 2013

In a brown field, the need to have a reliable well re-start and well activation method becomes increasingly important owing to the decline in reservoir pressure and possible heavy hydrostatic column after water breakthrough, leading to re-start and vertical lift difficulties. When this occurs, the well is said to be non-eruptive. The conventional method for solving this challenge is the use of gas-lift activation, which requires a gas source, compressors and scrubbers. Such equipments are currently unavailable on the Ofon field and a different approach to well activation had to be devised.

The Ofon field development plan was in two phases. The second phase, which includes conventional gas-lift activation, was scheduled to commence seven years after the start of the first phase. No provisions were made for conventional gas-lift of wells in the first phase of the project. Unfortunately, the second phase of the project has been delayed for almost 10 years. Consequently, a new approach was devised to restart wells with low eruptivity and artificially lift wells which have lost eruptivity.

The pseudo-gas lift method involves the use of a well with high GOR and high flowing well head pressure (FWHP) to lift another well through a surface pipeline called chicksan. The line is connected to the wellhead of the HGOR well via the swab valve on one end and the other end is connected into the annulus of the well requiring artificial lift. The implementation of this technique is simple and does not require additional equipment. This method has shown to be effective in cases where it is uneconomical to install a conventional gas lift unit, there are space constraints or there is delay in installing a conventional gas lift system as in the case of the Ofon field.

An additional oil production of about 16 MMbbls has so far been obtained from the field with the use of this pseudo gas-lift method. [M = 103].
Promoting Effective University-Oil Industry Research Collaboration In Nigeria
Authors: Falode Olugbenga A. , Nebeife Peter C.
Published: July 2013

Effective Research Collaboration between the University and Industry (U-I) plays a very important role in pushing the frontiers of knowledge and developing new technologies thereby making them powerful engines for innovation and economic growth. Some developed economies have achieved a long-standing tradition of collaboration between universities and industry which maintains a pool of subject-matter specialists within the academic community, ensuring handy solutions to emerging industry challenges, among other benefits. However in Nigeria, there is a growing gap between the academia and the industry. This may have contributed to the low rating of graduates from Nigerian universities in terms of technical competence, as many of the students’ research engagements are not tied to the industry.

This paper therefore aims to examine and evaluate the status of research collaboration that exists among petroleum engineering, geosciences schools and the oil industry, and recommendations to reinforce and enhance the effectiveness of U-I collaboration in Nigeria were proposed.

Joint research projects carried out between selected universities from the six geopolitical zones and the oil industry in the last two decades were analyzed in order to identify the barriers to effective U-I collaboration. Survey questionnaires were developed and administered to faculty members and oil industry managers to elicit the frequency of interaction by types of engagement and barriers. The survey data were analyzed using descriptive and inferential statistics.

The implications of the findings from this study are utilized to recommend policies aimed at facilitating effective U-I collaboration.
Issues, Trend And Opportunities For The Production Of Bio- Synthetic Paraffinic Kerosene (Spk)
Authors: Babatunde A. A , Egmba K. C , Kehinde A. J , Falode O. A
Published: July 2013

Biofuels are increasingly becoming a viable alternative for reducing consumption of petroleum, a policy goal resulting from recent high oil prices, energy security concerns, and climate change. More recently, projects have been initiated to map a way forward for the introduction of sustainable biofuels to help reduce dependence on fossil fuels in air transport and reduce GHG emissions by the air industry. Globally, various feedstocks and conversion technologies for production of biofuels for aviation are currently being investigated. The purpose of this paper is to present issues, trend and opportunities in the production of SPK as an alternative to the traditional fossil fuel. The work focuses on SPK as an aviation fuel with its attendant environmental benefits of reduction in CO2 emission. The paper also reviews different feedstock used in SPK production such as Jatropha, Camelina and Algae. Process technologies used are also surveyed.
Wellbore Stability Management In Depleted And Low Pressure Reservoirs
Authors: Fekete Paul O. , Adewale Dosunmu , Kuerunwa Anthony , Ekeinde Evelyn B. , Chimaroke Anyanwu , Odagme Baridor S.
Published: July 2013

New zones in mature fields continue to be actively developed as operators strive to maintain depleting reserves. Many of the world's new reserves are discoveries made below these existing, mature reservoirs. Drilling activities in or near producing or previously abandoned reservoirs often encounter large variations in pressure gradient as depleted layers or low pressured zones are exposed during the drilling process. Zones with pressures inconsistent with the overburden are often encountered, if conventional drilling techniques are used, then the higher mud weight used to hold back the target interval may result in massive losses (lost circulation), differential sticking, sloughing, or collapsing formations in the lower-pressure zone. There is a clear advantage to drilling if we could drill by reducing the drilling window between pore pressure and fracture gradient, using cage stress (particle bridging) or wellbore strengthen (WS) to drill at higher mud weights without losing fluid. This work presents the approach of WS that can be accomplished with treatment of the whole drilling fluid with Lost Preventive material (LPM) that are designed to seal and effectively increase fracture resistance allowing the operator to drill through a weak formation zone successfully with minimal to zero losses. Other models and materials were also investigated to determine their suitability and operational design parameters. Models for LPM application procedure (minimum volumetric requirements, quantitative requirements for filter cake thickness and optimise hydraulic parameters for effective cake deposition) were developed. The advantage of this process is reduction in drilling difficulties and non productive time for operators. Some experimental work was also carried out to determine the port throat of the formation, particle size distribution (PSD), strength & stability of the LPM filter cake, as well as the compatibility of different LPMs with different mud system. Results from case studies were also presented which shows tremendous result in reduction of NPTs via no loss circulation.
Study of Alcohol Mixtures for Enhanced Oil Recovery
Authors: Ikeagwu C. , Nyah F. J. , Onyekonwu M. O. , Ogolo N. A. , Ubani C.
Published: July 2013

Several techniques have been deployed to enhance oil recovery. Some have given good results while there is still the possibility that some materials that have not been tried might also have the capacity to enhance recovery. The underlying motivation for this study therefore is to find out the capacity of local materials to enhance oil recovery. Alcohol (palm wine) and water mixture and alcohol (palm wine) and starch mixture were used in various ratios to find out the ideal ratios that recovers oil most from sands.

Experimental results show that a mixture of alcohol and water and alcohol and starch can enhance oil recovery. For alcohol and water, oil recovery increased with an increase in alcohol content of the mixture. This could be attributed to reduction of interfacial tension between oil and water. For alcohol and starch, the ideal ratio of 1:1 gave the highest recovery. Beyond this ratio, oil recovery was observed to be reduced. The good result may have resulted partly from reduction of interfacial tension and partly as a result of increase in the viscosity of the displacing fluid.
Depletion of the Knowledge Base in the African Oil and Gas Industry -Women to the Rescue
Authors: Reginald-Ugwuadu Onyinye
Published: July 2013

Growing the African Oil and Gas industry requires a highly skilled and talented workforce for improved innovation and sustainability. With the increased job mobility and migration of the male workforce, it is imperative that the industry considers the emerging dynamics and seek other avenues for growing and securing local talent pool.

The current workforce in the oil and gas industry is predominantly male with a sprinkling of females in the existing talent and skill pool and even fewer opportunities for females in leadership roles. Diversity and inclusion initiative has recently helped to encourage policies that promote some considerations for the female workforce. However, there is still more work to be done.

This paper sets out a discourse on the issues, challenges and prospects for the oil and gas industry in Africa with primary focus on policies that identify and adequately utilize the skills and talents of the female workforce; maximizing their ingenuity in knowledge management and capacity building for the advancement and sustainability of the sector.

The exposition will recommend insightful roadmap towards ensuring consistent retention and improvement of the knowledge base in the industry as well as means and ways of attracting qualified and talented females.
Material Balance Modelling of Hydraulically Connected Reservoirs in a Single System: Case Studies
Authors: Nwaokorie Chukwuemeka , Ukauku Ikwan , Emelle Chima
Published: July 2013

The evaluation of the recoverable hydrocarbon volume and further development opportunities in complex reservoirs (where two or more reservoirs are hydraulically connected) primary challenges the engineer faces in managing such reservoirs. In this study, multi-tank material balance models have been built to solve these problems.

The key criteria for a robust material balance modelling of hydraulically connected reservoirs in a single system are: (i) transmissibility across the reservoirs should be properly defined. Transmissibility is a major modelling component in achieving sound multi-tank MBAL models. It is useful to the estimation of the rate of aquifer movement across the reservoirs. (ii) Good understanding of the geology and production data of the reservoirs is helpful in estimating the appropriate transmissibility. (iii) Sufficient and quality Carbon-Oxygen logs, BHP and production data. CO logs are very important for proper calibration of hydrocarbon contact. Accurate BHP data is critical in the establishment of dynamic communication and matching of simulated versus measured reservoir pressure.

In this paper two cases with over 30 years of production history are discussed in detail including the full methodology and the associated results. The results from these studies show good and reliable outcome which has provided the basis for the reported hydrocarbon resource volumes of the reservoirs (B1.0X, B1.0N, C1.0X, E9.0X, E10.0X, E11.0X, G1.0X, H1.0X)

Results were compared with other methodologies (existing simulation models and DCA of NFA wells) and indicate good comparisons. The number of development opportunities in the 8 reservoirs were optimised from 22 to 20 wells using the multi-tank material balance model.

Despite some known limitations of material balance generally, multi tank material balance model has proven to be a simple and reliable methodology in evaluating complex reservoir system with hydraulic communication. Especially, in situations where time and budget constraints will not support full field reservoir simulation modelling.
Application of Real-Time Fluid Sampling in Mature Fields: Case Study of Oben Field (Re-) Development Planning
Authors: Amedu J. A. , Nwokolo C. E. , Badmus O. M. , Ibrahim A. D.
Published: July 2013

The acquisition and interpretation of cased hole saturation logs is crucial to the effective execution of field development plans and maintaining a top notch well and reservoir management. However cased hole saturation logs in mature field developments characterized by low salinity formation water, saturated hydrocarbon liquids and gas condensates can unfortunately be beset with significant levels of non-uniqueness making it quite difficult to evaluate fluid types and establish clear fluid contacts. In such situations, real-time fluid sampling becomes the only way to properly delineate fluid phases. This paper showcases field experiences in the F7800 reservoir of the mature Oben field development and the structured approach applied in resolving such non-uniqueness in the planning and positioning of crestal oil producers.

Though the F7800 was initially undersaturated, well performances of the most crestal producer (well shut-in due to high GOR) and very sparse historical reservoir pressure data indicated the presence of a secondary gas cap due to pressure depletion way below the bubble point. As the downdip wells began to water out from aquifer influx, there arose a need to explore updip development opportunities. In the first identified opportunity, existing cased hole saturation logs acquired in an offset well indicated gas at the same level of the planned new development target interval. This interpretation threatened to erase the opportunity for further oil development.

In another structurally higher development opportunity, a time-lapse C-O log (taken three years apart) in the same well indicated fluid depletion down to residual oil saturation despite the fact that the perforation had been squeezed off for close to 20 years. Besides the interval was the most crestal in the structure and other downdip wells were producing dry oil. In both cases, the cased hole saturation log was at variance with the well established reservoir structure and the performance of development wells and inferred significantly less reserves. Consequently, reservoir pressures and fluid sampling/analyses were necessary to establish fluid types and contacts. The result was a 45ft upwards shift in the previously estimated fluid contact which allowed the placement of two updip development wells with a total net oil production in excess of 1500 bopd from the two updip developments. This paper will highlight the application of real-time fluid sampling technologies by a Niger Delta Operator to safeguard overall project value.
Alkali/Surfactant/Polymer Flooding Using Gum Arabic; A Comparative Analysis
Authors: Onuoha S. O. , Olafuyi O. A.
Published: July 2013

ASP flooding has been found to be one of the major EOR methods of successfully recovering light and medium oil left in the reservoir after primary and secondary oil recovery.

The objective of this study is to evaluate and compare the displacement efficiencies of two Alkali/Surfactant/Polymer slugs formulated with two different surfactants: an anionic and a non-ionic surfactant named Lauryl sulphate (Sodium Dodecyl sulphate, SDS) and Tween 80 (Polysorbate 80), respectively. The alkali employed was caustic soda (Sodium Hydroxide), and the polymer used here was Gum Arabic. Gum Arabic is an organic adhesive gotten from the hardened sap of the Acacia Senegal and Acacia Seyal trees, having similar molecular structure and chemical characteristics with Xanthan Gum, which is a widely used polymer for enhanced oil recovery. Gum Arabic is commercially available in Nigeria. Results from this study will prove the efficacy of Gum Arabic for use in the Nigerian oil and gas industry.

In this study, the chemicals were combined in the same composition and concentration to recover trapped oil after conventional water flooding. This was done by linearly flooding a horizontal core holder loaded with glass beads. The results from these experiments show that Lauryl sulphate and Tween 80 are both good candidates for enhanced oil recovery, with incremental recoveries of 36% and 15%, and displacement efficiencies of 90.2% and 77.9% respectively. This paper also covers laboratory and facility design requirements for implementing an ASP project.
Development of Heavy Oil Reservoirs: A Case Study of a Low API° Reservoir Offshore, Nigeria
Authors: Eremiokhale Obehi , Zeito George , Orioha Herbert
Published: July 2013

Heavy oil makes up approximately 15 percent of the world's remaining oil reserves. It presents opportunities that could be commercially viable but often rejected because of the inherent challenges of producing them, especially in offshore environments. These challenges include flow assurance, produced water separation and treatment and additional heat and power requirements. The common occurrence of low API reservoirs at relatively shallow depths can lower drilling and completions costs but can also increase production and transport costs and limit marketing options.

This paper describes the commercially successful production of a heavy oil reservoir offshore Niger-Delta. The field was discovered in 1968 and an appraisal well was drilled in 1970. At that time, the accumulations were deemed to be too small to develop. Forty years later the economics of oil production had changed and additional appraisal wells were drilled. Modern logs, core and MDT samples were taken. Three of the five reservoirs contained heavy oil. Reservoir simulations established initial estimates of recovery for each reservoir encountered and IPM models established inflow-outflow relationships. For the heavy oil reservoirs, the IPM showed that artificial lift would be required to produce the oil. This was confirmed by failed attempts to naturally flow an appraisal well that tested the best of the heavy oil reservoirs. The decision was taken to drill a horizontal pilot producer completed with a downhole ESP. The pilot producer was successful and several development wells were subsequently drilled in that reservoir and completed with ESP and gas lift capability.

This paper further showcases how the economics of producing a heavy oil reservoir was reversed by comingling with lighter crude and managing the challenges of crude compatibilities, produced water separation and marketing of the crude blend.
Estimating Reservoir Parameters Using Thermal Transient Testing (TDS Technique)
Authors: Nyame Michael , Dankwa Ohenewaa K.
Published: July 2013

In the estimation of most reservoir parameters in well test, the reservoir is assumed to be isothermal which is practically not true due to the fact that there are heat sources from friction in the wellbore, work done by the drill bit and as well as thermal recovery. Although, this temperature change is small, it can serve other beneficial purposes in the reservoir and the wellbore. The research work used the small change in temperature to estimate reservoir parameters like permeability and skin factor. This research work brought out equations to be used in the estimation these reservoir parameters and the applied to field data. This research work is applicable in reservoirs where steam flooding and in situ combustion processes are used as the enhanced oil recovery methods.

These result obtained for permeability was practically the same as the true reservoir permeability from field data although the same could not be said about the skin factor since that of the estimated and true value were quite different. This makes thermal transient testing a good substitute for the estimation of reservoir permeability. The same could not be said about the skin factor since it affect the pressure drop not temperature change.

This research work brought out the idea that thermal transient testing can be used as a tool for estimating some reservoir parameters as well as verification for estimated reservoir parameters using other well test methods.
Application of Neural Network Workflow to Facies Modeling in Turbidite Reservoirs, Offshore Nigeria
Authors: Njoku Chukwueke , Horst Peter , Akinsanmi Olatunji
Published: July 2013

Three dimensional static reservoir modeling is a key aspect of geoscience workflows underpinning development of petroleum reservoirs. It helps accurately characterize reservoirs, plan appraisal and development wells, and achieve high-level Well and Reservoir Management (WRM) over the production life.

Facies modeling is a critical step in the static modeling workflow because it allows us model how rock types are distributed in the reservoir and whichis the basis for modeling petrophysical property ranges associated with each facies type. The object-based approach to facies modeling has been well established within the oil and gas industry over the last ten years, however, recent efforts have been made to model reservoir facies using neural networks.

This paper reports on the application of the neural network approach to facies modeling as part of the static modeling workflow for several turbidite reservoirs in an offshore Nigeria oil field. The key input data applied to delineate and model the facies were cores, well logs, and seismic.

The authors consider this modeling approach to be successful and recommend it for modeling deep water facies with better thin-bed placement, high repeatability, and a shorter turn-around time.
Development of a User Friendly Computer Program for Designing Conventional Oilfield Separators
Authors: Olotu C. O. , Osisanya S.
Published: July 2013

The proper handling and processing of crude oil systems plays an important role in the economics of crude oil production. The separator is the first processing equipment for crude oil systems. Separator design procedures are cumbersome, time consuming, involve a lot of guesswork, and are prone to a lot of human calculation errors. Furthermore, subjectivity arises with each design procedure on the parameters necessary and crucial for separator design. Hence, there's a need to develop a user-friendly computer program to automate separator design. Separator design is based on empirical procedures that have been established based on sound engineering judgment.

In this work a user-friendly computer program was developed to estimate separator dimensions (diameter and height). Two design procedures, Svrcek and Monnery 1994 and the modified Arnold and Stewart 2008 were selected based on the parameters used in their design procedures. The equations involved in the two procedures are presented, and are used to develop four user-friendly programs to estimate 3-phase vertical and horizontal separator dimensions. The VISUAL BASIC programming language in Microsoft Excel was used to develop the computer programs.

The program was validated using case studies from reviewed texts. Both procedures show similar results for all the case studies. The Arnold and Stewart design procedures involve less guesswork and is more suitable for conventional oilfield separator design. The results also show a decrease in separator height and length as separator diameter increased. This trend was observed in both design procedures.
Production Casing and Tubing Design for HPHT Wells in the Niger Delta
Authors: Ayodele Akinfolarin , Sunday Awe , David Obiga , John Musa , Thompson Ukomah
Published: July 2013

High pressure and high temperature (HPHT) wells are wells with pore pressures in excess of 0.8psi/ft or wells that require surface pressure control equipment with ratings in excess of 10,000psi and static bottom hole temperatures higher than 300 deg F (150 deg C). Although a large un-developed hydrocarbon portfolio in the Niger Delta falls within the operating envelop of HP/HT, there is little or no record of current producing HPHT wells in the Niger Delta. One of the reasons could be the commercial attractiveness of the conventional wells that are still being produced. The other reason could be the risk and complexity of the wells in terms of design, execution and operation.

However of recent a number of operators have started or are in the process of starting HPHT campaigns. The essence of this paper is to outline the design methodology that has been followed in the design of some HPHT wells in the Niger Delta and share some of the factors that should be taken into consideration in the design of such high-risk and complex wells
Bubble Point Pressure Prediction Model for Niger Delta Crude using Artificial Neural Network Approach
Authors: Numbere O. G. , Azuibuike I. I. , Ikiensikimama S. S.
Published: July 2013

Knowledge of bubble point pressure is very important in reserve estimation and other petroleum engineering calculations such as modeling of fluid flow through porous media and multiphase flow in pipes. Usually, this property is obtained from laboratory PVT analysis. However, when such analysis is not available, empirically derived PVT correlations are used. This work focuses on the use of an Artificial Neural Network (ANN) to address the inaccuracy of empirical correlations used for predicting bubble point pressure. The ANN is a mathematical model inspired by biological neural networks. In this modeling approach 1248 data sets collected from the Niger Delta Region of Nigeria were used. The data set was randomly divided into three parts, of which 60% was used for training, 20% for validation, and 20% for testing. The accuracy of the new Artificial Neural Network was compared with existing empirical correlations. The ANN model outperformed the existing empirical correlations by the statistical parameters used with a best rank of 17.3132 and better performance plot.
Coupled Model for Analysis of Multilayer Reservoir in Commingled Production
Authors: Onwunyili Christian Chime , Onyekonwu M. O
Published: July 2013

Presently, most of multilayer reservoirs are modeled as a one single zone system by averaging the reservoir properties correspondent to each zone in the reservoir. This procedure is easy for the analysis of the total production and wellhead pressure. Nevertheless, the result of this type of modeling would rarely be accurate because a one-zone system does not take into account that each zone's pressure decline independently. This pressure decline for each zone affects the overall production and would amount to inter-flow and to early depletion of one of the zones. Therefore this study attempts at coupling the wellbore hydraulics and pay-zone fluid behavior to determine the contribution of the various zones to the overall production in multilayer reservoirs. The study employed analytical solutions to the equations that model the fluid flow in porous media and considered that pressure difference between the producing zones at the sandface allows wellbore inter-flow during any stage of the reservoir's life and no pay-zone inter-flow. The result of typical production scenarios are presented by developing a robust simulator allowing the calculation of the prevailing fluid flow and pressure profiles along the wellbore and the various reservoir zones of different rock properties. The simulation approach presented here allows the user to set the optimal production, injection, or shut-in conditions at the surface for reservoir systems containing two zones.
Enhanced Oil Recovery using Foam Injection; a Mechanistic Approach
Authors: Sunmonu Rasak Mayowa , Onyekonwu Mike
Published: July 2013

On the average, conventional production methods will produce from a reservoir about 30% of the initial oil in place. The remaining oil, nearly 70% of the initial resource, is a large and attractive target for enhanced oil recovery methods. One of the EOR techniques used is gas flooding. Gases used in gas-flooding (such as CO2, Hydrocarbons, N2, etc.) are normally less viscous (more than one order of magnitude less) and less dense than both water and crude oil, which results in gas channelling through the high permeability zones and gravity overriding. Thus, gas flooding normally has poor volumetric sweep efficiency, especially in an immiscible displacement, with the displacing phase being a lower viscosity. A need for mobility control in gas flooding has led to the use of foam for sweep improvement and profile modification. Foam is employed to improve the efficiency by which the displacing fluid sweeps the reservoir and contacts and recovers oil.

The objective of this study is to investigate the application of foam injection as an enhanced oil recovery process in Reservoirs. This research was aimed at investigating the possible Increase in Nigeria's Oil production through the use of foam to reduce gas mobility in the porous media, consequently improving volumetric sweep efficiency and oil recovery.

In conducting this research, a static model was developed using a static modelling software, the model was then populated with Petrophysical properties peculiar to sandstone reservoirs. Pressure volume and temperature properties as well as pressure and saturation dependent properties were defined for the model using relevant correlations. The model was then simulated using a dynamic modelling software to mimic the foam injection process.

Results such as field oil recovery, cumulative oil recovery, gas oil ratio, water cut and production rate were compared with the case in which gas injection without foam is been implemented. A significant increase in oil recovery was observed for the foam injection case compared to the gas flooding without injection while a significant reduction in gas oil ratio and gas produced was observed. This was due to the reduction in gas mobility caused by the presence of foam in the reservoir. A simple economic analysis tool was then used to determine the economic feasibility of the project which was discovered to be viable.
Predicting the Produced Boil off Gas in the Moss Spherical Liquefied Natural Gas (LNG) Vessel
Authors: Aimikhe V. J , Kinigoma B. S , Iyagba E. T
Published: July 2013

This paper focuses on developing a boil off gas model that can be used to predict values of boil off gas produced onboard a Moss spherical liquefied Natural Gas (LNG) Vessel. The Fourier law of heat transfer and Newton's law of cooling mathematical models were used to derive equations and then estimate the total heat transfer rate from the containment system under consideration. While maintaining the internal tank pressure, LNG composition and varying the ambient temperature and voyage length; using the concept of mean daily average temperature (MDAT), the boil off gas rate was estimated, hence a Moss Spherical LNG vessel boil off gas model was developed. Actual Boil off gas values were compared with values obtained by using the model developed in this study. The robustness of the equations derived allows the user to be able to develop various Moss Spherical boil off gas simulators for tanks with different types of materials. The statistical error analysis showed an Average Absolute Error of 5.63% and Standard Deviation of 7.3 when the results from this study were compared with actual boil off gas values obtained from a Moss Spherical LNG vessel.
Objectives and approaches in the breeding of perennial legumes for use in temporary pasturelands
Authors: Naydenova G. , Hristova Ts. , Aleksiev Y.
Published: July 2013

Legumes are the major element of grassland ecosystem, on which the forage
quality depends. Breeding of pasture varieties in perennial legumes firstly
aims at achieving tolerance and persistence of the legume component in the
pasture. In species having low natural grazing tolerance (lucerne and red
clover) it is necessary to conduct breeding for biological, morphological and
physiological characteristics, directly related to grazing tolerance. In the
species having high grazing tolerance (white clover, birds foot trefoil,
sainfoin), the pasture persistence is considered as a function of particular
morphological characteristics, adaptive potential and stress tolerance. The
indirect breeding for pasture persistence includes also breeding for
competitive ability and co-adaptivity with grass pasture species adapted to
the region and practices of cultivation, as well as breeding for improved
nodulation and nitrogen fixation as an important element of the adaptive
ability. The breeding for grazing tolerance and persistence is concentrated
also on the mechanisms of self-maintenance of the legumes in the pasture -
vegetative reproduction, spread and self-seeding. Many breeding programmes
are concentrated also on morphology providing better intake by the animals,
on main and specific quality characteristics, on anti-nutrient factors, on
adaptation to systems and practices of pasture establishment and use. The
breeding strategy using germplasm consolidated through the mechanisms of
specific adaptation to unfavourable or specific agro-ecological conditions
and influences - i.e. breeding through ecotypic selection is considered to be
the most efficient for grazing purposes. The interactions in the system:
pasture species - companion species in the pasture herbaceous community -
grazing animals (kind, category, grazing style and behaviourial reactions)
and the applied regime of use of the pasture are direct and strong. These
interactions are of essential importance in genotypic differentiation of the
pasture ecotypes. The adaptive variability of the pasture ecotypes is used
directly, as well as in recombination breeding.
Commercial enzyme influence on broilers fed different levels of wheat
Authors: Seifi S.
Published: July 2013

An experiment was conducted to evaluate the efficacy of multienzyme
supplement (Natuzyme?) in diets containing wheat on the broilers performance.
A total of one hundred twenty day old male broiler chicks (Arbor Acres) were
randomly assigned to 6 treatments with a 2 3 factorial arrangement (0, 150
and 300 gram per kilogram wheat and 0 and 0.025 gram per kilogram enzyme).
Chickens were fed with starter, grower and finisher diets during 1-21, 22-
35, 36-49 days of the age, respectively. Body weight gain, feed intake, and
feed conversion ratio were determined weekly and productivity efficiency
index was determined at the end of experiment. Litter moisture was evaluated
at the age 21 days. The results indicated that although different levels of
multi-enzyme and wheat had no significant effect on body weight gain, feed
intake, feed conversion ratio, productivity efficiency index and litter
moisture but caused partial improvement in these parameters.