bluuebunny/crossref_metadata_2025 huggingface dataset:
The neuroprotective effect of magnesium sulfate in preterm fetal mice
Authors: Cho Geum Joon , Hong Hye-Ri , Hong Soon-Cheol , Oh Min-Jeong , Kim Hai-Joong
Published: December 2014

To investigate the use of magnesium sulfate (MgSO

On embryonic day 15 of gestation, lipopolysaccharide (LPS) and mifepristone (RU486) were used, respectively, to create mouse models of inflammation and noninflammation-associated preterm birth. After intraperitoneal injection of LPS, RU486, or normal saline solution (NS), dams were randomized to intraperitoneal MgSO

The expression of S100B significantly differed among the groups and was decreased in the LPS+MgSO

We observed that prenatal treatment with MgSO
Influence of Joint Flexibility on Vibration Analysis
of Free-Free Beams
Authors: Gunda Jagadish Babu , Krishna Y.
Published: December 2014

In present work, joint flexibility (or looseness)
of the free-free beam is investigated by using a two noded
beam finite element formulation with transverse displacement
and joint rotations as the degrees of freedom per
node at joint location. Flexibility of the joint is primarily
represented by means of a rotational spring analogy,
where the stiffness of the rotational spring characterizes
the looseness of the flexible joint for an applied bending
moment. Influence of joint location as well as joint
stiffness on modal behavior of first five modes of slender,
uniform free-free beams are discussed for various values
of non-dimensional rotational spring stiffness parameter.
Numerical accuracy of the results obtained from the
present finite element formulation are validated by using
the commercially available finite element software which
shows the confidence gained on the numerical results discussed
in the present study.
Series solution to coupled nonlinear heat and
moisture transfer in slabs with
temperature-dependent diffusivities
Authors: Chiba Ryoichi
Published: December 2014

The two-dimensional differential transform
method (DTM) is applied to solve the one-dimensional
coupled heat and moisture diffusion problem for a slab
with temperature-dependent thermal and moisture diffusivities,
which are expressed by a linear function and
an exponential function of temperature, respectively. One
surface of the slab is subjected to convective hygrothermal
loading and the other has constant prescribed temperature
and moisture. Approximate analytical (series) solutions
for the temperature and moisture profiles in the
slab are derived. The transformed functions included in
the solutions are obtained through a simple recursive procedure.
Numerical results for a slab subjected to a sudden
change in surface temperature illustrate the effects of
temperature-dependent diffusivities on the transient temperature
and moisture profiles of the slab. The results indicate
that the nonlinear effect originating from the varying
moisture diffusivity is not negligible for resin composites.
The DTMis a useful new analytical method for solving
nonlinear coupled transient problems.
Fish Friendly Farming: Water, Wine, and Fish—Sustainable Agriculture for a Thirsty World
Authors: Gundling Ernest
Published: December 2014

This case study focuses on Fish Friendly Farming, part of a nonprofit organization, the California Land Stewardship Institute. The FFF program is an example of an innovative model for cooperative public-private environmental collaboration and stewardship. The case provides a history of FFF and its ability to create networks and collaborations between parties that typically find it difficult to work together. This case focuses both on sustainability issues related to land and farming, and on challenges related to scaling up a successful nonprofit organization.
Green Innovation Games: Value-Creation Strategies for Corporate Sustainability
Authors: Lampikoski Tommi , Westerlund Mika , Rajala Risto , Möller Kristian
Published: December 2014

This study builds on insights from 49 sustainability leaders in the U.S. by examining green innovation from the game perspective. It explores how corporate sustainability can advance environmentally friendly innovations, and what managerial roles and activities are required to enable the transformation. It identifies four green innovation games characterized by different underlying value creation logics and organizational and mental barriers. The article suggests ways that can help managers to overcome these barriers and incorporate three decisive managerial roles into their corporate agenda and culture to advance corporate sustainability.
Pregnancy may favour the development of severe autoimmune central diabetes insipidus in women with vasopressin cell antibodies: description of two cases
Authors: Bellastella Giuseppe , Bizzarro Antonio , Aitella Ernesto , Barrasso Mariluce , Cozzolino Domenico , Di Martino Sergio , Esposito Katherine , De Bellis Annamaria
Published: December 2014

Recently, an increased incidence of central diabetes insipidus (CDI) in pregnancy, and less frequently in thepost partumperiod, has been reported, most probably favoured by some conditions occurring in pregnancy. This study was aimed at investigating the influence of pregnancy on a pre-existing potential/subclinical hypothalamic autoimmunity. We studied the longitudinal behaviour of arginine–vasopressin cell antibodies (AVPcAbs) and post-pituitary function in two young women with a positive history of autoimmune disease and presence of AVPcAbs, but without clinical CDI, and who became pregnant 5 and 7 months after our first observation. The behaviour of post-pituitary function and AVPcAbs (by immunofluorescence) was evaluated at baseline, during pregnancy and for 2 years after delivery. AVPcAbs, present at low/middle titres at baseline in both patients, showed a titre increase during pregnancy in one patient and after delivery in the other patient, with development of clinically overt CDI. Therapy with 1-deamino-8-d-arginine vasopressin (DDAVP) caused a prompt clinical remission. After a first unsuccessful attempt of withdrawal, the therapy was definitively stopped at the 6th and the 7th month ofpost partumperiod respectively, when AVPcAbs disappeared, accompanied by post-pituitary function recovery, persisting until the end of the follow-up. The determination of AVPcAbs is advisable in patients with autoimmune diseases planning their pregnancy, because they could be considered good predictive markers of gestational orpost partumautoimmune CDI. The monitoring of AVPcAb titres and post-pituitary function during pregnancy in these patients may allow for an early diagnosis and an early replacement therapy, which could induce the disappearance of these antibodies with consequent complete remission of CDI.
The comparison of entrepreneurship ability of dairy farms in Lithuania, Latvia, Estonia and Poland
Authors: Jedik Andrej , Stalgienė Aldona , Aamisepp Marju , Bratka Valda , Zekalo Marcin
Published: December 2014

According to the agricultural Census data, dairy farms with less than 20 cows (small-scale dairy farms) have the biggest share of dairy farms structure in Lithuania, Latvia, Estonia and Poland. It leads to the importance of entrepreneurship ability evaluation in small-scale farms among these countries. However, there are no researches about comparison of entrepreneurship ability of small-scale farms among mentioned countries. The article investigates a comparison of the farmers’ entrepreneurship ability in small-scale dairy farms in mentioned countries by using distribution terms. The aim of the article is to perform calculations of small-scale dairy farms’ entrepreneurship ability for each country, give comparison analysis of the data among countries and estimate fitted distributions of entrepreneurship ability for further modelling purposes. The entrepreneurship ability and fitted distributions are evaluated by using optimization methods. The complex comparison method is also provided to show the general situation of the dairy farms in the selected countries. The results of the investigation show that Poland takes relatively the best position in the dairy farms’ economy. Latvia and Estonia take up relatively weaker positions. The calculation of the entrepreneurship indicators for each country shows that Estonian farmers have the highest entrepreneurship ability level. Two third of Estonian small-scale dairy farms’ correspond the entrepreneurship of 0.8 and a higher level. Latvian, Lithuanian and Polish dairy farms’ owners have similar average entrepreneurship ability (0.6–0.7) with different standard deviations. The best fitted distributions for all countries are normal and truncated normal distributions.
Social entrepreneurship as an innovative solution mechanism of social problems of society
Authors: Kostetska Irina , Berezyak Ivanna
Published: December 2014

For each country, regardless of its socio and economic development, one of the main key indicators of success is the social stability of society. That is why the use in practice of such innovation to our society as a social technology social entrepreneurship became actual. The aim of the paper is theoretical and methodological grounding of necessity and feasibility of using social entrepreneurship as a generator of socially oriented economic development and the development of practical recommendations for implementation and development in Ukraine. The methodological basis of the study were theoretical methods of scientific knowledge, the use of which has made it possible to reveal the wider possibilities of social entrepreneurship in solving the social problems. According to the results of the study it can be stated that social entrepreneurship as a social innovation has found its niche and its place in the new information and innovation, innovation economy and continues to gain momentum. In Ukraine, such a business can set a goal of occupational therapy, social rehabilitation, and introduction new mechanisms in order to solve these social problems. Based on a systematic approach to the problems of integration of social enterprises in the economy of Ukraine was founded that for further development of the state should provide favorable conditions, in particular, to establish the legal and tax conditions for the creation of social enterprises, to realize favorable form of systemic interaction between government, business and citizens, to create favorable institutional environment for social enterprises.
Enhancement of innovation management and technology study programme
Authors: Stašys Rimantas
Published: December 2014

In 2013 a new postgraduate study programme was created. Since the study programme has been running for a year now, a decision to evaluate the quality of the study programme. Objective of the Study: to evaluate the quality of study programme and, having analysed the aims and the results of the postgraduate study programme, to determine the aspects that would enhance the preparation of innovation managers. A quantitative study is the basis of this empirical study: a structured written survey. Study programmes accurately match the main needs of students and the results are important and relevant for the preparation of innovation managers. The quality of the study programme can be and needs to be improved: by actively using case analyses, by integrating workers of innovation companies into the curriculum of the study programme, by changing the ratio between lecture time and practicum time, by creating specific methodical guidelines for the preparation of a final project in this study programme.
Improving sand with microbial-induced carbonate precipitation
Authors: Shahrokhi-Shahraki Rahim , Zomorodian Seyed Mohammad Ali , Niazi Ali , O'Kelly Brendan C.
Published: December 2014

Microbial-induced carbonate precipitation using urea hydrolysis is a relatively new improvement technique for granular soils. An important factor in achieving uniform calcite deposition (and hence consistent improvements in geomechanical properties) throughout the treated soil mass is the protocol adopted for injecting the reagents of ureolytic bacteria, urea and calcium. This paper reports a laboratory study investigating a technique to treat two loose medium quartz sands using different injection strategies. Staged injection including retention periods, and with a pressure head applied during injection of the bacterial cell solution, proved most effective. Sand specimens were treated using different concentrations of bacterial cell and urea–calcium chloride solutions and for a single injection cycle. Measured strength and stiffness values from unconfined compression tests ranged from 50 to 240 kPa and from 6 to 56 MPa, respectively. Permeability coefficient values were reduced by up to approximately one order of magnitude. Hence, a single injection cycle adhering to the proposed treatment method did not significantly affect the drainage capacity of the sand media. Greater improvements in stiffness and strength were achieved for lower bacterial cell and higher cementation solution concentrations, with a higher molarity of urea (non-equimolar solutions) proving even more effective. These findings were confirmed by scanning electron microscope observations.
Effect of fine ceramic recycled aggregate (RA) and mixed fine RA on hardened properties of concrete
Authors: Etxeberria Miren , Vegas Iñigo
Published: December 2014

The ceramic industry is well known for producing large amounts of rejected ceramic waste. During the construction and demolition waste crushing process, a large amount of fine recycled aggregates (FRA) are usually produced. However, little research work has been carried out employing those types of aggregates in recycled aggregate concrete (RAC) production. In this research work, mixed and ceramic FRA in partial replacement of 10, 20, 35 and 50% of natural fine aggregates were used in order to verify their applicability in RAC manufacturing. All the concretes were produced to have the same workability. The physical, mechanical and durability properties of the RAC were determined and compared with the results obtained for conventional concrete. The results showed that an increase in the percentages of FRA used in the concrete production led to a decrease in density and an increase in water absorption. The mechanical and durability properties of all the concretes produced with fine ceramic recycled aggregates were similar to those of conventional concrete at 28 days. However, after 1 year, the compressive strength and chloride diffusion of the RAC mixtures produced using fine ceramic recycled aggregates were considerably higher than those of conventional concrete.
Open Complete Medial Talar Dislocation without Fracture of the Talus or the Malleoli
Authors: Hosny Hossam
Published: December 2014

Case:

A twenty-three-year-old man presented with an open complete medial talar dislocation without fracture of the talus or the malleoli; this was associated with an injury to the posterior tibial artery and the tibial nerve. It was difficult to reduce because of entrapment of the tendons of the flexor digitorum, the flexor hallucis longus, and the tibialis posterior, as well as entrapment of the posterior tibial artery and the tibial nerve. At the twelve-month follow-up, the talus did not show osteonecrosis.

Conclusion:

After a complete medial talar dislocation, the patient was found to have no arthritis or osteonecrosis, and he had return of normal sensation at one year postinjury.
Buckling of Buoyancy-Assisted Tubulars
Authors: Arslan Mehmet , Ozbayoglu Evren M. , Miska Stefan Z. , Yu Mengjiao , Takach Nicholas , Mitchell Robert F.
Published: December 2014

Use of buoyancy provides multiple solutions to overcome the drag problem for wells with shallow and high step-out profiles. Although both full- and partial-flotation methodologies have been used successfully to extend the reach in many field cases, the influence of buoyancy on tubular instability has not been investigated yet. This paper presents an extensive experimental and analytical study, focusing on static tubular instability inside horizontal wellbores with emphasis on buoyancy. In terms of the experimental research, running tubulars into horizontal wellbores was simulated with four different pipes, varying buoyancy, and varying loading speed. Throughout the tests, axial loads both applied to the pipe and transmitted through the pipe were recorded simultaneously, with respect to pipe displacement. Experiments reveal that currently existing models give reasonable approximations as long as buoyancy is not included in the tests. The major interpretation from the experiments is contrary to what currently existing expressions imply (i.e., tubular buckles immediately as effective weight approaches zero; even for naturally buoyant conditions, considerable amount of axial load is still required for both buckling initiation and helix formation). As buoyancy increases further, results and predictions diverge from each other considerably. To eliminate the discrepancies between results and predictions, theoretical study was conducted. Empirical correlations that also consider the influence of buoyancy on critical buckling loads are presented. Finally, another pipe was also tested within different buoyancy conditions to validate the equations developed. Experimental results of this pipe closely match the new analytical findings. This experimental and analytical study provides useful results for future applications with buoyancy-assisted tubulars, in terms of practical engineering and design calculations.
Drillstring Mechanics Model for Surveillance, Root Cause Analysis, and Mitigation of Torsional Vibrations
Authors: Ertas Deniz , Bailey Jeffrey R. , Wang Lei , Pastusek Paul E.
Published: December 2014

Vibrations have been identified as one of the most-frequent and persistent performance limiters by limiting weight on bit, rate of penetration, or borehole quality even when they may be low enough not to cause damage to downhole tools and equipment.

A general purpose drillstring mechanics model has been developed to analyze axial and torsional vibrations in the frequency domain and provide vibration indices indicative of dysfunction in these modes. The model uses transfer matrices to solve for harmonic perturbations around a baseline solution obtained from a torque/drag type analysis, and accounts for effects of well path, tool joints, viscous damping caused by the drilling fluid, surface-boundary conditions, bit characteristics, and special vibration mitigation tools. The model supports workflows for real-time vibration surveillance as well as post-drill root cause analysis and well redesign. For example, real-time stick/slip severity monitoring is enabled by use of 1-second surface measurements. As a well redesign tool, a large number of design alternatives can be quickly evaluated to mitigate vibrations.

Case studies using high-frequency surface/downhole drilling mechanics data validated the model and identified three types of torsional dysfunctions with distinct signatures and mitigators: unstable stick/slip, an instability associated mostly with the lowest-frequency torsional resonance of the drillstring; bit/bottomhole assembly stall, which is intermittent, sudden mechanical jamming at the bottom of the drillstring; and synchronous torsional oscillation, which is the amplification of periodic excitations at torsional resonances of the drillstring. In one case study, the stick/slip surveillance tool was superior to real-time downhole measurements in lag time, bandwidth, and accuracy. In another case, the root cause of prevalent unstable stick/slip was identified as velocity-weakening aggressiveness of the bit. Of the redesign options, the use of a topdrive controller tuned to damp out the lowest-frequency torsional resonance was deemed most effective. One such controller was evaluated in the field and was very effective at mitigating stick/slip in subsequent wells.
Drillstring Analysis With a Discrete Torque/Drag Model
Authors: Mitchell Robert F. , Bjørset Arve , Grindhaug Gaute
Published: December 2014

The only standard drillstring model in use today is the torque/drag model because of its simplicity and general availability. Field experience indicates that this model generally gives good results but sometimes performs poorly. For example, some friction loads predicted for casing running in horizontal wells have not been consistent with field data.

In the standard torque/drag model, the drillstring shape is taken as the wellbore shape. However, given that the most-common method for determining the wellbore shape is the minimum-curvature method, this assumed wellbore shape forces the bending moment to be discontinuous at survey points. This defect is dealt with by neglecting the bending moment.

A different approach assumes that the drillstring position corresponds with the minimum-curvature wellbore only at discrete points. The obvious choice for these discrete points is at the positions of the tool joints in the drillstring. Although these tool joints are fixed in position, they are allowed to rotate within the wellbore. These extra degrees of freedom allow solution of the bending-moment problem, because continuity of bending moment can now be ensured at each tool joint. This paper gives a complete description of the drillstring calculation. Typical torque/drag problems are studied to compare the two torque/drag formulations. These studies give comparisons in drag forces and torques for the two models, and for the new formulation, the magnitude of the bending moments.
Investigation of Nanoparticle Adsorption During Transport in Porous Media
Authors: Zhang Tiantian , Murphy Michael J. , Yu Haiyang , Bagaria Hitesh G. , Yoon Ki Youl , Neilson Bethany M. , Bielawski Christopher W. , Johnston Keith P. , Huh Chun , Bryant Steven L.
Published: December 2014

Nanoparticles (diameter of approximately 5 to 50 nm) easily pass through typical pore throats in reservoirs, but physicochemical attraction between nanoparticles and pore walls may still lead to significant retention. We conducted an extensive series of nanoparticle-transport experiments in core plugs and in columns packed with crushed sedimentary rock, systematically varying flow rate, type of nanoparticle, injection-dispersion concentration, and porous-medium properties. Effluent-nanoparticle-concentration histories were measured with fine resolution in time, enabling the evaluation of nanoparticle adsorption in the columns during slug injection and post-flushes. We also applied this analysis to nanoparticle-transport experiments reported in the literature.

Our analysis suggests that nanoparticles undergo both reversible and irreversible adsorption. Effluent-nanoparticle concentration reaches the injection concentration during slug injection, indicating the existence of an adsorption capacity. Experiments with a variety of nanoparticles and porous media yield a wide range of adsorption capacities (from 10–5 to 101 mg/g for nanoparticles and rock, respectively) and also a wide range of proportions of reversible and irreversible adsorption. Reversible- and irreversible-adsorption sites are distinct and interact with nanoparticles independently. The adsorption capacities are typically much smaller than monolayer coverage. Their values depend not only on the type of nanoparticle and porous media, but also on the operating conditions, such as injection concentration and flow rate.
The Use of Modeling To Enhance the Analysis of Formation-Pressure Integrity Tests
Authors: Alberty M.W.. W. , McLean M.R.. R.
Published: December 2014

Formation-pressure integrity tests (FPITs) are used to verify the integrity of cement at a casing shoe, measure the stress state of the exposed formations for well planning and operations, and determine the maximum equivalent circulating density to which a shoe can be safely exposed. Critical decisions on operations are made directly from the results and include decisions about the need for remedial cement operations, maximum mud weights that can be used to drill the next well section, minimum mud weights that can be used to prevent hole collapse, calibration factors for predicting fracture gradients, and the potential need for lost-circulation-mitigation strategies.

The interpretation techniques of the result most frequently focus on the point at which a fracture first starts, the point at which unstable fracture growth begins, or the closure pressure of the fracture when pumping ceases. However, the early pressure-buildup behavior is often overlooked and can provide much insight on the integrity of cement, the point of the start of a fracture, the permeability of the formation being tested, the need for cement remediation, and the potential to increase fracture resistance by use of wellbore-strengthening techniques.

This paper presents a model for predicting early pressure-buildup behavior, discusses how the model can be used to improve the interpretation of FPITs significantly, and provides examples of the application in select wells.
Threat-and-Error Management: The Connection Between Process Safety and Practical Action at the Worksite
Authors: Thorogood J.L.. L. , Crichton M.T.. T.
Published: December 2014

High-reliability organizations have five important characteristics: a preoccupation with failure, a reluctance to simplify, sensitivity to operations, resilience, and a respect for expertise. Experience from recent incidents suggests that these qualities may generally be lacking in organizations that manage drilling operations today. Research sponsored by oil-and-gas producers and others has suggested that creating a sense of “chronic unease” in relation to barrier integrity and operation of safety-critical systems, combined with understanding of the psychological issues that create error-producing conditions, will strengthen defenses against major accidents occurring. The question remains as to the best way to embed the necessary skills through teaching, coaching, and assessment and their integration into routine working practices.

Experience from aviation suggests that successful implementation of nontechnical skills needs to be combined with a clearly defined operational framework. Such an operational framework, however, is not widely observed in the drilling community at present. A standardized approach that defines how drilling operations are to be executed, activities monitored, decisions made, or changes managed in a time-constrained environment provides the context in which the necessary individual and organizational skills can be taught. Training needs to address the underlying psychological theory—in particular, cognitive biases—of nontechnical skills to counter threats and errors in the workplace.

The paper summarizes the principles of high-reliability organizations and their contribution to process safety in the context of drilling operations. Then, we describe Threat-and-Error Management, which evolved from aviation-based Crew-Resource Management to produce the levels of safety that today we accept as normal. We introduce operational risk management in drilling as the analogous link with aviation. The paper concludes by illustrating how one can use these concepts in drilling operations to enhance routine risk-management activities, and presents a description of the tools and techniques involved.

The advantage of this approach is that effective nontechnical skills can be observed, coached, and assessed on a routine basis in the workplace. Active use of these methods in everyday drilling operations promotes the essential characteristics of a high-reliability organization by instilling the sense of chronic unease and concern for barrier integrity, thereby reducing the chance of minor anomalies cascading into major accidental events.
Real-Time Casing-Design Optimization: A Case Study in the Use of Managed-Pressure Drilling To Develop an Adaptive Well Design and Eliminate Casing Strings on a Deepwater Exploration Well
Authors: Sugden Catherine , Bacon William , Gabaldon Oscar , Borges José Umberto , Soares Cristiane Maravilha , Falcão José Luiz , Nogueira Emmanuel Franco , Vanni Guilherme Siqueira , Chita Luiz Carlos
Published: December 2014

A Petrobras deepwater exploration well is planned to be drilled in water depth greater than 2438 m (8,000 ft) offshore Brazil. As is typical of deepwater wells, it has a narrow drilling window between pore pressure and fracture gradient, requiring many casing strings to reach total depth (TD). Because pressure-related problems are often extremely costly when drilling conventionally in deep water, initial design assumptions were conservative, assuming the maximum pore pressure and minimum fracture gradient for casing-point and pipe selection. As with all conventional casing designs, the resulting pipe has limited capacity to withstand increased burst and collapse loads associated with extending hole sections if the opportunity arises.

Managed-pressure drilling (MPD) enables the development of an adaptive well design by providing three key advantages over conventional drilling: the ability to detect kicks and losses extremely accurately (in gallons, rather than barrels); the ability to rapidly respond to and dynamically control detected kicks and losses by adjusting backpressure on the annulus, keeping kick volumes small; and the ability to perform dynamic pore-pressure and formation-integrity tests. Detecting and responding rapidly to kicks allows for the well to be designed with smaller kick tolerances. Furthermore, by keeping the kicks small, they can be circulated out quickly without requiring conventional, time-consuming well-control operations, which often lead to further hole problems. When this advantage is coupled with dynamic pore-pressure tests and dynamic formation-integrity tests, real-time optimization of casing points can be achieved safely with reduced risk of costly well-control incidents.

The method presented here, applicable to any deepwater well, uses low, expected, and high pore-pressure and fracture-gradient estimates to develop an adaptive casing design for the well. In this paper, kick-tolerance calculations for selecting casing points by use of MPD are defined. The effect of reduced kick-tolerance requirements because of the application of MPD is demonstrated, and an adaptive procedure for real-time design optimization of the well is presented. The method results in decision criteria that identify key depths where casing strings can be eliminated without compromising the ability to reach objective TD. The resulting adaptive casing design will most likely eliminate at least one, and has the potential to eliminate two, casing strings, representing significant cost savings.
Casing Expansion as a Promising Solution for Microannular Gas Migration
Authors: Kupresan Darko , Heathman James , Radonjic Mileva
Published: December 2014

The objective of this research was to investigate the potential effect of expandable-casing technology on the cement sheath and remediation of sustained casing pressure (SCP) caused by microannular gas migration. Varying magnitudes of SCP exist in the Gulf of Mexico, where more than 80% of casing strings exhibiting SCP are production and surface casings, representing a great technical, economic, and environmental risk. Situations in which SCP is observed usually result in costly and frequently unsuccessful remediation efforts.

A unique bench-scale physical model was used to simulate expansion of a previously cemented casing under field-like conditions. Experimental measurements obtained before and after low-percentage pipe expansion exhibited improvement of cement/pipe interface. Successful multirate flow-through experiments with nitrogen gas showed the effectiveness of this technique in sealing of microannular-gas-leakage pathways, providing ideal remediation of SCP immediately post-expansion; and after up to 60 days of post-expansion, the seal integrity was intact.
Avoid Pilot Holes, Land Wells, and Optimize Well Placement and Production With Deep Directional Resistivity Logging While Drilling
Authors: Dupuis C.. , Mendoza Barrón V..
Published: December 2014

Landing horizontal wells in a reservoir is a critical task, and the accuracy of the result drives the economics of a well. Except when the geological environment is largely predictable, relying on well-to-well correlation techniques or on pilot holes fails to mitigate important risks in landing most wells. This paper details how a different solution more effectively manages the risks of a landing operation. The deep directional resistivity (DDR) logging-while-drilling (LWD) tool has been in use in dozens of fields around the world. The key features of the technology that play a role in derisking the landing of wells range from the tool hardware (which enables a deep depth of investigation, sensitivity to direction, and a wide frequency range) to the surface interpretation software, which provides real-time automatic multilayer inversion. Applied to a landing in a North Sea field, the DDR LWD service was part of the solution for meeting ambitious field-development targets.
Optimization of Well Placement to Minimize the Risk of Scale Deposition in Field Development
Authors: Hutahaean Junko , Demyanov Vasily , Arnold Dan , Vazquez Oscar
Published: December 2014

Determining an optimal location and configuration of well to be drilled is a critical reservoir development decisions as it can cost millions of dollars and determine the volume of hydrocarbons being produced. This is a very challenging task due to large number of decision variables involved. One important factor to consider in field development is scale deposition. It can cause production problem and reduce hydrocarbons recovered. In the extreme case, it can cause a production well to be abandoned as a result of formation damage in the near wellbore or narrowing of the production tubing. Due to the potential high cost of scale management, scale risk deposition would be an important issue.

The aim of the paper is to optimize the placement of new wells in a field development accounting for the risk of sulphate scale deposition. This scale is formed when sulphate rich seawater, usually used as injection fluid to maintain reservoir pressure, mixes with barium rich formation brines. Multi-Objective Optimization (MOO) is used to find a range of solutions by maximizing oil recovery and minimizing scale risk. Scale risk deposition is modelled by tracking the injected seawater concentration, which acts as a natural tracer, in the produced water from each well. Penalty parameter is introduced in the optimization workflow and quantified by relating the scale risk impact in the reservoir production to scale treatment (bullhead-squeeze) as the mitigation. The study used a modified version of the benchmark reservoir model, PUNQ-S3; the model was adapted to be developed using seawater flooding, and as a result sulphate scale deposition is of a major concern. Particle Swarm Optimization (PSO), a stochastic population-based and gradient-free optimization algorithm, is applied to search over the new well locations and their completion zones in the presence of potential scale deposition risk.

The paper compares a conventional field optimization with objective only to maximize oil production to the one with accounting scale risk as extra information. The paper demonstrates that multi-objective optimization allows us to identify well locations and completion zones with high recovery and yet low scale risk, leading to significant economic benefit in a number of field development scenarios.
Factors Controlling Shale Gas Production: Geological Perspective
Authors: Mallick Monalisa , Achalpurkar Manoj
Published: December 2014

Trapped gas within the matrix and fractures of source rock shales is termed as "shale gas." Geologically, the shale-gas-bearing formations are fine-grained, organic-matter-rich (0.5 to 25%), porous, but impervious sedimentary strata with natural gas trapped in the pores, natural fractures, and/or adsorbed onto the clay surface. The primary factors related to the geology and geochemistry of the formation that govern shale gas production potential would be porosity, permeability, natural fracturing, their original hydrocarbon-generating potential, and the amount of gas still present in the formation. Hydrocarbon-generating potential includes the amount of organic matter originally deposited or the total organic carbon content (TOC), types of source organic matter or kerogen type, thermal maturity and hydrocarbon-generating capacity or gas yield, and the extent of conversion of source organic matter to hydrocarbon. These factors again depend largely on the availability of organic matter, depositional environments, depth of burial, local geothermal gradient, and degree of metamorphism. Hydrocarbon-producing potential further depends on the network of natural fractures, microporosity, adsorption, etc. The impervious nature of shale gas formations requires extreme natural or artificial fracturing (fracture stimulation) to recover commercial quantities of gas. Hydraulic fracturing and horizontal drilling are successful techniques recently used for commercial shale gas production, which depend on geomechanical properties, such as mineralogy and brittleness/ductility of the formation. However, selection of drilling and stimulation methodology requires knowledge of other geological parameters, such as the arrangement of the bedding planes, stratigraphy, natural fracture porosity and intensity, clay content, shale-water absorption, fluid-water sensitivity, shale capillary, shale fractal pattern, shale hydration, gas-shale fracture conductivity, relation of geological features of the formation with regional geological settings, and spacial and temporal variation of reservoir parameters. These parameters govern the direction of fracture propagation, gas recovery rate, and wellbore stability of the drilled well, and also aid in determining base-fluid salinity and fluid-type selection for a fracturing treatment. The aim of this paper is to elucidate the geological processes related to shale gas formations for the development of the proper technology to aid hydrocarbon recovery.
Implementation of Coupled 3D Geomechanics and Discrete Fracture Network (DFN) Models in Field Development Optimisation: A Case Study from Carbonate Reservoir, Abu Dhabi
Authors: Ali Edris M. A. , Haggag Amin M. , Al Benali K. , Shinde A. L. , Ghadimipour A. , Perumalla S. V. , Hartley L. J. , Baxter S.
Published: December 2014

An onshore oilfield in Abu Dhabi has complex faulted structure of early Cretaceous carbonate reservoir. The porosity in these reservoirs ranges up to 25%. These reservoirs are overlaid by dense carbonate which acts as a cap rock. The field has been produced for 35 years with peripheral water and gas injection scheme to maintain the reservoir pressure.

The objectives of this geomechanical study were to verify the impact of in-situ stresses and rock mechanical properties on reservoir performance during production/injection activities, as well as to evaluate the mechanical and hydraulic responses of natural fractures and faults to fluid flow within the reservoir. In addition, evaluation of cap rock integrity and fault seal analyses are also considered as necessary risk assessment inputs for field development program.

Extensive rock mechanics testing program has been carried out on reservoir, the interlay dense and cap rock to quantify the contrast in mechanical rock properties and their response to in-situ stresses. Diverse set of data have been integrated including geological, geophysical, petrophysical, reservoir and drilling data to build robust 1D and 3D Geomechanical models. Natural fractures were characterized using core inspection, image logs and CT- Scans which have been calibrated to production logging (PLT) and well tests. Multi-attribute analysis with inputs from petrophysical, structural and geophysical data has been used to build and calibrate the 3D DFN model.

The developed 3D Geomechanical model was coupled with the 3D reservoir dynamic model in order to predict the changes in total stresses due to reservoir pressure changes. Furthermore, this model was integrated with the 3D DFN model to help understand the impact of production/injection activities on the mechanical behaviour of the fractures, fault seal and cap rock integrity.

This paper discusses the role of coupled 3D Geomechanics and the DFN modeling in evaluating and quantifying the mechanical behaviour of reservoir rock matrix, fractures, faults and cap rock that can influence the decisions on optimum field development planning.
Compositional Surveillance Program for Assessing Prudhoe Bay Vaporization Process
Authors: Bharat Jhaveri , Becky Steen , Michael Connolly
Published: December 2014

Prudhoe Bay field, the largest oil and gas accumulation in North America, has a large gas cap in communication with the oil rim. In addition to the liquid condensate held in the gas phase, the original gas cap contains relict oil that exists in the liquid phase at low saturations and is remnant of the oil migration - spill history of the reservoir. One of the key recovery mechanisms at the Prudhoe Bay field is the use of lean gas injection to increase recovery through vaporization of relict oil and dropped-out condensate in the original gas cap, and residual oil in the expanded gas cap. The lean gas vaporization project was implemented with an initial installed gas handling capacity of 2 BCF/D which was successively expanded to 8 BCF/D in several Gas Handling eXpansion (GHX) projects making it the largest hydrocarbon gas injection project in the world. After processing the produced gas to manufacture NGLs and Miscible Injectant, the lean gas is reinjected into the Prudhoe Bay gas cap for pressure support and vaporization of liquid phase hydrocarbons. In addition to estimates of black oil benefits, design and commercial evaluation of each stage of the gas handling expansion required accurate prediction of vaporization benefits from lean gas injection.

A compositional surveillance program was designed and implemented to assess the efficiency of the vaporization process in the field. This paper describes the surveillance program in which the routine separator tests conducted at the specified well locations for fluid allocation and production optimization are modified to include additional measurements of extended separator gas compositions and separator oil API gravity. The paper also presents details of an analytical procedure in which the measured compositional information from the well tests is used together with other relevant field data to deduce the effectiveness of the vaporization process. The compositional surveillance data analysis procedure is demonstrated by application to the gravity drainage area of the Prudhoe Bay field. Deliberate application of the compositional surveillance data acquisition and analysis by the Prudhoe Bay Reservoir Management team will significantly impact the optimization of the vaporization process in the field.
Integrated Asset Modeling of a Gas Condensate Field Operating Under Gas Recycling Mode
Authors: Torrens Richard , El Gohary Mohamed , Al Bairaq Ahmed , Kumar Arun
Published: December 2014

An integrated asset model (IAM) was constructed for an onshore carbonate gas condensate asset in Abu Dhabi. The strategic priority of the field is to optimize recovery of liquids and, therefore, the field is operated under gas recycling. After processing, dry gas is reinjected for the purpose of maintaining reservoir pressure to maximize condensate recovery. However, gas is a critical natural resource, and so a strategic decision was taken in 2011 to assign a portion of the produced gas for sales and use nitrogen as a makeup fluid to maintain reservoir voidage. The long-term implications of this decision will be the need for installation of nitrogen rejection units to ensure produced gas meets sales specifications after the field blows down.

The IAM brought together reservoir, well, pipeline, and facilities domain models into an integration platform that provides an increased level of modeling fidelity by removing some of the simplifying assumptions and enabling cross-discipline collaboration to achieve understanding of the asset's problems and objectives. The model itself is complex and comprises a multimillion-cell reservoir simulation model, production and injection pipeline models, and a simplified model of the gas processing facility, all of which utilize a fully compositional approach to fluid modeling. The model was validated over a period of 6 months of production history by comparing calculated rates and pressures with measured field data from the field at the facility, trunkline, and well level. Once the validation phase was completed, the IAM was used to predict life of field performance.

The IAM approach provided critical information not available from traditional standalone modeling. Firstly, more accurate accounting for the backpressure impact on the production and injection wells resulted in significant differences in production and injection profiles. Secondly, the inclusion of a facility model to update the injection composition resulted in major differences in nitrogen production. Finally, as a result of collaboration with facilities production, operations, and facilities teams during the project, the historical match to condensate production was considerably improved.
Successful Application of Intelligent Completions in Al Khalij Field
Authors: Briz-Quintero X. , Sofyan M. , Pouget P. , Le-Roch J. , Authier J. , Deffous Y. , Gurses S. F. , Gulamov E. , Mukashev N. , Jaafar M. R. , Abul-Hamd I. , Al-Naimi A. R.
Published: December 2014

The first successful field wide application of intelligent completion technology in TOTAL worldwide has been installed in Al Khalij field wells. The Al Khalij field, located offshore Qatar, was discovered in 1991 and put into production in 1997. The field is formed of a highly heterogeneous carbonate reservoir with significant remaining dynamic uncertainties, making reservoir management a challenge. Moreover, given the currently high field water cut (WCT = +/- 90%), any operation to decrease it, without a detrimental impact on the productivity, can have a large impact on its oil potential.

The standard Al Khalij oil producer well architecture has around 3000 m of horizontal drain across the reservoir, of which half is completed on 7″ or 6 5/8″ cemented and perforated liner and half is a 6″ or 5 3/4″ openhole extension. All the oil producer wells are lifted with electrical submersible pumps (dual ESP standard). Since 2007, Total E&P Qatar started deploying intelligent wells for reservoir zonal control, monitoring and enhanced management. Currently 28 intelligent completions have been installed in the field, with a low misrun rate (1 out of 29). Such completions have allowed selective down hole flow control without any additional heavy intervention (i.e. shift sliding sleeves in horizontal well). In the year 2011 and 2012, for the first time in TOTAL Group, a number of 3 Flow Control valves have been installed in two Al Khalij wells.

Given the ease of manipulating multi-position flow control valves, the Al Khalij intelligent completions can be manipulated regularly in order to acquire inflow information (Low-cost PLT) and optimize the well behavior. In 2013, the control valves operations brought extra oil of up to +/-5% of the field production.

This paper details the design, planning and execution of the intelligent completion technology in the Al Khalij field and covers the value generated value for field development.