bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimum Rate Estimation Guide in Mature Water-Prone Reservoirs
Authors: Obe Ebenezer , Davis Rick , Reynolds Ken , Ibrahim John , Oragwu Aluba , Chukwu Festus 
Published: July 2011

Abstract
In this paper, an empirical method that enables estimation of a critical choke, and corresponding production rate beyond which there is a high risk of early water breakthrough, is proposed.
The method involves the plot of the log of the average of well test rates at various choke settings. All the reservoirs investigated in this manner indicated a characteristic hump shape with some notable features. Hence characteristic reservoir models corresponding to selected Niger Delta reservoirs were developed and validated with well tests of recent drills.
Furthermore, a theoretical justification for this observation was realised by applying a slight mathematical manipulation of the Gilbert's correlation, which relates surface production with the choke.
Finally, deductions from the correlation yielded a two-phase flow shift factor that can be used to match Gilbert's correlation to actual performance.
A Quick Look Drilling Evaluation Tool
Authors: Ani Bonaventure. O. , Egbon Franck , Fusier Francis 
Published: July 2011

Abstract
Globally, drilling simulators are used extensively for proffering drilling solutions which save time and reduce cost in order to meet up with the demanding E & P activities. This paper presents a new drilling software – PETDRILL® which is developed for quick evaluation and analysis of some key drilling and well control operations which include: determination/evaluation of burst, collapse and tensile stress requirements per drilling phase; auto determination of minimum casing type per drilled phase, custom casing design, hydraulic power requirements based on well profile, mud volumes and spec, abnormal pressure regimes, mud densities, and a guide to Well Control for vertical wells. PETDRILL also graphically displays in 3D, the existing sub-surface geological layout which improves riser placement and better view of existing well profiles.
Finally, this software proffers a better drilling solution and will give a quick look evaluation and estimation of on-the-job drilling parameters and at the same time, serve as a learning tool for drilling students.
Phase Behaviour Measurements of the Fluid Properties in Flowing Multiphase Hydrocarbon Streams
Authors: Mmata B. , Azubike A. , Ikeji K. , Onyekonwu M. 
Published: July 2011

Abstract
Knowledge of the phase behaviour and the availability of accurate fluid properties are crucial in all stages of exploration and production of petroleum reservoir. To accurately quantify individual fluid phase in a production stream; calculate the water cut as well as convert flow rates from flow line conditions to standard conditions, the phase behaviour and volumetric properties of the fluid are imperative.
Previously, the practice has been to generate some of these physical properties such as density at flow line conditions. By using the principle of ideal solutions; densities at standard condition were measured in a laboratory and subsequently converted to flow line conditions by correcting for compressibility and thermal expansions.
This paper introduces a direct experimental method of obtaining the fluid properties at the exact prevailing flow line temperature and pressure. Representative flow line samples from some offshore wells in the Niger Delta region were studied. The behaviour of these samples was investigated and important fluid properties like the anhydrous oil densities at flow line conditions, water densities, oil shrinkage, gas gravity and stock tank oil gravity were measured.
These data can be used as input parameters in production system calculations such as in coriolis multiphase flow meters, to obtain precise oil, water and gas flow rate from individual wells and fields. They can also be used for proper reservoir management, well optimization, fiscal allocation and volume record custody transfer at pipeline station or port terminals.
Predicting Critical Internal Diameters of Onshore LNG Storage Tanks for Minimizing Boil Off Gas Production
Authors: Aimikhe V J. 
Published: July 2011

Abstract
This paper focuses on developing a model for predicting internal tank diameters that will yield minimum boil off gas production in LNG above ground double wall metallic storage tanks. Critical analysis was carried out for various tank capacities ranging from 20,000m3 to 520,000m3. In each case the heat transfer from the cylindrical bodies and the ellipsoidal/hemispherical tops were calculated and the produced boil off gas determined. For each tank studied, the imternal diameter was varied and the corresponding effective boil off gas rate obtained. The values of the internal diameters corresponding to the minimum boil off gas rate were recorded as critical internal diameters. A relationship was found to exist between the values of critical internal diameters obtained and tank capacities from which an equation was developed empirically. On comparing the values of critical diameter obtained from the equation developed in this study with actual values of critical internal diameters calculated from other models, the results indicated an average error of −0.105%, an average absolute error of 2.04% and a standard deviation of 2.43.
Prediction and Monitoring of Oilfield Carbonate Scales Using Scale Check©
Authors: Eseosa Abbe , Atubokiki Ajienka Joseph 
Published: July 2011

Abstract
One of the major problems facing oilfield operations is the occurrence of scale. In oilfields the mixture of produced water and formation water is unavoidable as produced water can be used to enhance production through water re-injection. The occurrence of scale in oil wells may cause flow restriction resulting in production damage, emergency shutdowns, increased maintenance costs due to frequent work-overs and an overall decrease in the production efficiency.
Formation water from field XYZ in the Niger Delta region was analyzed to predict the scaling tendency of the water using the General Solubility Index for Calcium carbonate. A scaling program Scale-Check© was written based on the Stiff-Davis predictive model, Langelier's predictive model and the General Solubility Index; these helped to calculate the scaling Index. Scale-Check© was used to predict the scale formation tendency of calcium carbonate scale for Well XY over three periods within the life of the well. Sensitivity analysis that showed the effect of temperature and pressure on carbonate scaling was also implemented.
Scale-Check© presents an easy-to-use program for checking the scaling tendency of formation or produced water and hence putting in place proactive measures that go a long way to reduce the negative effects of scaling in the oilfield.
Pressure Drop Mechanism in Horizontal and Inclined Multiphase Flow Pipes under Low Sand Loading
Authors: Oluyemi G. F. , Olusegun T. O. 
Published: July 2011

Abstract
This study provides more insight into multiphase flow of fluid in horizontal and inclined pipe configurations under a low sand loading condition. A steady-state turbulent flow simulation of complex oil-water-gas-solid multiphase flow was conducted to ascertain the impact of increased wall roughness on sand transport and pressure drop in horizontal and inclined pipes at low sand loading. Specifically, the pressure drop mechanism in these pipe configurations was investigated for a specified sand particle size and loading limit. Investigation was done using a 2 metre pipe length with physical model created in Gambit and computation implemented using Fluent 6.3. Results obtained demonstrate that at low sand loading, sand particles deposit on the internal surface of pipe forming an extra layer of material. This extra layer of sand particles results in a superficial increase in pipe roughness which contributes to the observed increase in pressure drop in the systems.
Rim Oil Economic Maximum Efficient Rate and Reserve Potential Evaluation
Authors: Ike I. A. , Mbee O. 
Published: July 2011

Abstract
Rim oil reservoirs are often associated with either large water aquifer or gas cap or both. These conditions often present unique challenges in the economic viability of these properties due to the high coning tendency during production. Due to the limited resource potential of these reserves, the cost involved in evaluating their economic potentials in the first place and the optimal production rate to be employed in their eventual development are not infrequently hard nuts to crack for developers.
Various schemes have been advanced for the development of oil rims including strategic well placement, intelligent well completion, etc. Determination of the most important factors that control recovery in thin oil columns using generic simulation to aid assessment is an interesting scheme even though the end product is known to sometimes deviate from physical and mathematical trends. Restricting production to critical rate figures is often not practicable.
In this work, a simple procedure amenable to computer coding employing critical rate and after breakthrough behavior correlations and modest data is developed to calculate the economic maximum efficient rate (MER) for the development of oil rims with water coning challenge. The MER so computed can be used as a cost effective reserve potential evaluation tool for preliminary assessment of thin oil column properties.
The accuracy of this method is a direct function of the critical rate and after breakthrough behavior models used in its development. This can be a great advantage as it ensures that the procedure can be adapted to any reservoir condition for which suitable correlations are available or can be developed. It also implies that models that are more in keeping with physical and mathematical principles can be put to use.
Semi-Analytical Models on the Effect of Drilling Fluid Properties on Rate of Penetration (ROP)
Authors: Alum Moses A. , Egbon F 
Published: July 2011

Abstract
Rate of penetration (ROP) plays a major role in drilling optimization and several attempts have been made to obtain a mathematical model for ROP. In this work, semi-analytical models for ROP were developed based on the original Bourgoyne and Young Model using real time bit records obtained from wells drilled in Niger Delta reservoirs. Simple regression analysis was applied on the equation on the parameter that contains differential pressure (j=4), to obtain regression constants which were then used to generate mathematical relationship between rate of penetration (ROP) and drilling fluid properties. Equations relating ROP to annular pressure losses, plastic viscosity for annular flow under laminar and turbulent conditions, as well as gel strength/yield stress were developed, plots obtained from these equations showed that penetration rate increases as annular pressure losses, and plastic viscosity under laminar and turbulent flow decreases, and increases as yield stress increases. Hence confirming the trend obtained from practical drilling experience, however the (R2) values obtained for viscosity and yield stress ranged between 50-62% and 88% for annular pressure losses. The (R2) values so obtained for mud properties such as plastic viscosity and yield stress/gel strength showed that although these properties affect ROP, their net effect is actually not as significant on ROP as they are thought to be, only annular pressure losses seemed to drastically affect ROP which is evident as it is directly related to equivalent circulating density (ECD).
The Integrated Technology of Water Detection, Shutoff and Regulating Separate Layer Production in the Oil Recovery Process
Authors: Zhou WanFu , Zhang ShuJin , Yu Lei , Zhou Quan , Shi Lei , Liu ChunRong 
Published: July 2011

Abstract
At present the Daqing oilfield is the largest inland oilfield, also is one of the oversize sandstone oilfield in the world. This paper enumerated some problems in the water injection stage of Daqing oilfield, just like the Daqing oilfield is in the extra-high water-cut stage that the oil layer's average water content was above 91.6%, the interlayer permeability had great difference, the interlayer cross flow occurred in practical production process that caused the well water content raised rapidly, too difficulty to confirm the water yield layers and developed the regulating separate layer production technology suited the inclined well, controlled directional well, this technology applied the mechanical, electronic, chemical method to integrate the water detection, shutoff and regulate the separate layer production together into the whole string, separated many controversial high water cut layers in one trip to improve the water detection reliability and the water shutoff treating pertinence, controlled the water cut increasing speed effectively. This technology can realize water detection, shutoff and control to regulate arbitrary separate layer production in practical production process, the whole strings' valid period was three years. In view of Daqing's geologic feature, the other assorted techniques were researched, using the chemical water shutoff technique to shut off the interlayer water channelling abidingly and give these technologies' application principles in this paper. The integrated technology of water detection, shutoff and regulating separate layer production was applied to 351 well in field application, the mechanical water shutoff was applied to 131 well and average well was separated for four layers. The chemical water shutoff was applied to 220 well, the individual layer maximum plugging thickness was 25.5m. After the implementation treating, the production rate increased and the producing liquid reduced obviously, the individual well producing liquid reduced to 28-43m3/d, the water content reduced to 1.5%-11.1%. The water shutoff valid period was one year at least. Through the aforementioned technologic research and the field applications, it provided a self-contained and economic rationally technology of water detection, shutoff & regulating separate layer production for the Daqing oilfield petroleum sustainable exploitation. At the end of this paper, one inclined oil well and one oil well's oil production testing result indicates this integrated technology not only founds and shutoff the high water production oil layers but also regulates to increase these oil layers' production effectively in the oil recovery process with the extra-high water-cut stage. All these regulating operation processes don't need stop production and don't having to kill well.
Validation of a Pseudocomponent Scheme for Nigerian Heavy Oil and Bitumen
Authors: Lawal Kazeem A. 
Published: July 2011

Abstract
Recently, a set of six pseudocomponent (PC) schemes was proposed for general characterisation of the Nigerian heavy oil and bitumen 1. However, the performance of the schemes is yet to be assessed. Given the laboratory-measured viscosity versus temperature relationship of a sample of the Nigerian bitumen, this paper employs the PC schemes to construct and tune fluid models to the viscosity dataset. Although all the cases show reasonable agreements (average absolute deviation below 25%) between measured and fitted data, the best and worst performances are obtained with the 4-PC and 1-PC schemes, respectively.
The tuned fluid models are then applied in thermal reservoir simulation studies. With a generic but representative reservoir-sector model, the dynamic response of the Nigerian bituminous deposit to the recovery method of steam-assisted gravity drainage (SAGD) is investigated. Simulation results indicate excellent consistency among the 3, 4, and 5-PC schemes but the 1- and 2-PC schemes deviate markedly from the higher-component approximations. As might be expected, the 1-PC model can not explain the solution gas reported in the Nigerian bituminous belt.
From the specific case studied, at least three PC's may be required to enable satisfactory characterisation of the Nigerian heavy crude for general applications. This initial conclusion follows from the comparative accuracy and computational efficiency of the ternary (3-PC) model. Future efforts should focus on generating additional experimental datasets, including but not limited to viscosity, on the Nigerian bitumen and evaluating the robustness of our preliminary conclusion.
Safeguarding Well Integrity in a Deepwater Field – The Bonga Field Experience
Authors: Ebitu Sophia , Orekyeh Uchenna , Bogaert Philip 
Published: July 2011

Abstract
Bonga oil producer wells are capable of delivering high rates in excess of 20 Mbopd; thus, any breach of well safety critical barriers could potentially lead to significant people asset and environmental damages. In addition, deferment caused by well integrity would also significantly impact production. Therefore, well integrity management remains an integral part of Shell's "Must Wins" and the Bonga team is focused on ensuring that we can demonstrate that the Bonga wells remain "safe and healthy" while delivering against production targets. One of the key challenges faced in the deepwater environment is the prohibitive high cost of rig intervention for diagnosis and remediation of well equipment failures; hence the well integrity management approach in the Bonga field places a lot of emphasis on use of alarm settings to operate wells within defined operating envelopes; proactive monitoring of the well operating parameters and consistent high compliance on preventive maintenance. This has resulted in the early detection of well integrity issues and minimal shut-in periods of wells for well integrity related failures. Also, innovative and cost effective methods of integrity repairs using an ROV deployed by the field intervention vessel have been implemented in the Bonga field. This article describes the application of Well Integrity Management in the Bonga deepwater environment and highlights some of the challenges and lessons learned in safeguarding the integrity of deepwater wells through the operational phase.
Wellbore Strengthening and Borehole Stability: A Geomechanical Model to Increase the Thin Mudweight Window in Vertical and Deviated Wellbores
Authors: Bassey Akong , Dosunmu Adewale , Buduka Stanley , Alabi Tunde 
Published: July 2011

Abstract
Saving time and money are the results of the stable bore hole design. During drilling there are two main instability problems, namely, bore hole collapse and fracture. The consequences of these drilling problems are severe, even the most simple bore hole collapse or break down can lead to the loss of millions of dollars in equipment and valuable natural resources. The main aspect of the well bore stability analysis is to mitigate these drilling problems. This is typically investigated by a constitutive model to estimate stress around the well bore, coupled with failure criterion. The objective of this study is to develop a model to widen the operating mud window by increasing the shear strength which involves reducing the minimum mudweight required to keep the hole open, and also increasing the near – wellbore compressive tangential stress which is coupled with the increase in maximum mudweight prior to fracture initiation. The most common approach for stability analysis is a linear elastic and isotropic constitutive model in conjunction with linear failure criteria like Mohr-Coulomb. The Mohr- Coulomb failure criterion only involves the maximum and minimum principle stresses and therefore assumes that the intermediate principle stress has no influence on rock strength. In addition, it is believed that the fluid barrier, and a part of the bore hole wall, behave plastically which provides higher fracturing pressure than conventional elastic theory. In this paper, a model for the mud weight window determination, using Mogi-Coulomb failure criterion and the elasto plastic model is developed. This is based on the hypothesis that, indeed elastic constitutive model does not fit with the reality of the well bore wall behavior and intermediate principle stress plays an important role on rock strength. This model leads to easily computed expression for the critical mud pressure required to maintain well bore stability and obtain a wider mudweight window for borehole strengthening during vertical and deviated well operations.
Analysis of Binding of KIR3DS1*014 to HLA Suggests Distinct Evolutionary History of KIR3DS1
Authors: O’Connor Geraldine M. , Yamada Eriko , Rampersaud Andy , Thomas Rasmi , Carrington Mary , McVicar Daniel W. 
Published: July 2011

Abstract
NK cell activity is regulated by the integration of positive and negative signals. One important source of these signals for human NK cells is the killer Ig-like receptor (KIR) family, which includes both members that transduce positive and those that generate negative signals. KIR3DL1 inhibits NK cell activity upon engagement by its ligand HLA-Bw4. The highly homologous KIR3DS1 is an activating receptor, which is implicated in the outcome of a variety of pathological situations. However, unlike KIR3DL1, direct binding of KIR3DS1+ cells to HLA has not been demonstrated. We analyzed four key amino acid differences between KIR3DL1*01502 and KIR3DS1*013 to determine their role in KIR binding to HLA. Single substitutions of these residues dramatically reduced binding by KIR3DL1. In the reciprocal experiment, we found that the rare KIR3DS1 allotype KIR3DS1*014 binds HLA-Bw4 even though it differs from KIR3DS1*013 at only one of these positions (position 138). This reactivity was unexpectedly dependent on residues at other variable positions, as HLA-Bw4 binding was lost in receptors with KIR3DL1-like residues at both positions 199 and 138. These data provide the first evidence, to our knowledge, for the direct binding of KIR3DS1+ cells to HLA-Bw4 and highlight the key role for position 138 in determining ligand specificity of KIR3DS1. They also reveal that KIR3DS1 reactivity and specificity is dictated by complex interactions between the residues in this region, suggesting a unique functional evolution of KIR3DS1 within the activating KIR family.
Myeloid-Derived Suppressor Cells Infiltrate the Heart in Acute Trypanosoma cruzi Infection
Authors: Cuervo Henar , Guerrero Néstor A. , Carbajosa Sofía , Beschin Alain , De Baetselier Patrick , Gironès Núria , Fresno Manuel 
Published: July 2011

Abstract
Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, affects several million people in Latin America. Myocarditis, observed in the acute and chronic phases of the disease, is characterized by a mononuclear cell inflammatory infiltrate. We previously identified a myeloid cell population in the inflammatory heart infiltrate of infected mice that expressed arginase I. In this study, we purified CD11b+ myeloid cells from the heart and analyzed their phenotype and function. Those CD11b+ cells were ∼70% Ly6G−Ly6C+ and 25% Ly6G+Ly6C+. Moreover, purified CD11b+Ly6G− cells, but not Ly6G+ cells, showed a predominant monocytic phenotype, expressed arginase I and inducible NO synthase, and suppressed anti-CD3/anti-CD28 Ab-induced T cell proliferation in vitro by an NO-dependent mechanism, activity that best defines myeloid-derived suppressor cells (MDSCs). Contrarily, CD11b+Ly6G+ cells, but not CD11b+Ly6G− cells, expressed S100A8 and S100A9, proteins known to promote recruitment and differentiation of MDSCs. Together, our results suggest that inducible NO synthase/arginase I-expressing CD11b+Ly6G− myeloid cells in the hearts of T. cruzi-infected mice are MDSCs. Finally, we found plasma l-arginine depletion in the acute phase of infection that was coincident in time with the appearance of MDSCs, suggesting that in vivo arginase I could be contributing to l-arginine depletion and systemic immunosuppression. Notably, l-arginine supplementation decreased heart tissue parasite load, suggesting that sustained arginase expression through the acute infection is detrimental for the host. This is, to our knowledge, the first time that MDSCs have been found in the heart in the context of myocarditis and also in infection by T. cruzi.