bluuebunny/crossref_metadata_2025 huggingface dataset:
Reduced electrical resistivity of reaction-sintered SiC by nitrogen doping
Authors: Jeon Young-Sam , Shin Hyunho , Lee Young-Hyun , Kang Sang-Won
Published: March 2008

A post heat treatment of reaction-sintered SiC at 1700 °C in nitrogen atmosphere significantly reduced electrical resistivity. A trace of insulating Si3N4 phase was detected via nitrogen heat treatment in high-resolution transmission electron microscopy observation; however, based on x-ray photoelectron spectroscopy, the evidence of nitrogen doping into SiC lattice has been claimed as the mechanism to the decreased resistivity. The increase of the total volume of SiC was apparent in x-ray diffraction during the nitrogen heat treatment, which was interpreted to stem from the growth of the nitrogen-doped intergranular SiC particles and surface doping of the primary SiC to reduce the contact resistance between the primary SiC particles.
How the Accelerated Reader Program Can Become Counterproductive for High School Students
Authors: Thompson Gail , Madhuri Marga , Taylor Deborah
Published: March 2008

Two pressing education reforms entail improving students' reading skills and improving high schools in the United States. In this article, the authors focus on both of these issues by adding the voices of students in an underperforming high school to the discussion about reading reform. We present the results of a larger study pertaining specifically to the views of students who participated in eight focus groups, in which students questioned the implementation of the Accelerated Reader (AR) program. There were five reasons that students did not like the program's implementation and claimed that it did not increase their motivation to read, making AR counterproductive. The results suggest that reading reform strategies that may work at the elementary level may not be as effective for adolescents, and that in order for true high school and reading reform to occur, the views and unique needs of older students must be examined and taken more seriously.
Does Feeling Come First? How Poetry Can Help Readers Broaden Their Understanding of Metacognition
Authors: Eva‐Wood Amy L.
Published: March 2008

Assuming that readers' emotional responses can enhance readers' metacognitive experiences and inform literary analysis, this study of 11th‐grade poetry readers features instruction that models both cognitive and affective reading processes. The author

Presents a case for more explicit attention to emotion in language arts classrooms

Provides a practical overview of the “think‐and‐feel‐aloud” instruction used in a poetry classroom

Describes the reading strategies students drew on to help them understand poems

Analyses of classroom discussions indicated that students used four strategies, which appeared to be driven primarily by sensory and emotional responses rather than cognitive processes alone. These included

Responding to key words and phrases

Visualizing and using the senses

Relating the text to personal experiences

Identifying with the poems' speakers

Based on the study's findings, the article provides justification for a more expansive definition of metacognition, which includes “thinking about feeling.”
Musing: A Way to Inform and Inspire Pedagogy Through Self‐Reflection
Authors: Moore Jane , Whitfield Vickie Fields
Published: March 2008

Teaching is a complex profession that involves grappling with a variety of management styles; federal, state, and local mandates; local policies and agendas; and informed curriculum practices that affect pedagogy. Teachers work in increasingly diverse schools, and they must be reflective practitioners to deal with the many social and educational issues that converge in such places. A reflective practitioner is better able to grow and defend teaching practices.
A Critical Analysis of Eight Informal Reading Inventories
Authors: Nilsson Nina L.
Published: March 2008

For this content analysis study, the author examined and cross‐compared the various ways in which eight informal reading inventories (IRIs) published from 2004 to 2008 address key issues relevant to new U.S. federal guidelines and the National Reading Panel's five critical components of reading instruction. Results suggest the IRIs range in technical rigor, with only one providing sufficient reliability data to support use of alternate forms. Measures for comprehension and vocabulary are more common than for fluency, phonemic awareness, and phonics. Some of the IRI authors offer passages in Spanish. All of the IRIs have their strengths and limitations, but each one offers special features that set it apart from the others. Results have implications for literacy‐related professionals searching for IRIs well‐suited to various educational settings and classroom contexts.
Shared Readings: Modeling Comprehension, Vocabulary, Text Structures, and Text Features for Older Readers
Authors: Fisher Douglas , Frey Nancy , Lapp Diane
Published: March 2008

A study of 25 expert teachers and their shared reading lessons in grades 3–8 suggests that teachers focus their modeling during shared reading in four categories: comprehension, vocabulary, text structures, and text features.
Comprehension Windows Strategy: A Comprehension Strategy and Prop for Reading and Writing Informational Text
Authors: Bass Mary Lee , Gee Woo Deborah
Published: March 2008

Comprehension Windows Strategy (CWS) is an informational text strategy that enhances comprehension during the processes of reading and writing and includes an easy to create instructional prop. CWS provides a structure for assisting students in the essential processes of understanding and organizing information; it is a means for improved comprehension.

CWS addresses multiple learner outcomes, specifically it (a) facilitates building a content knowledge base, (b) organizes facts, (c) motivates students to become active readers and writers, (d) supports critical thinking, and (e) introduces proper documentation and use of citations. In addition, this strategy can be used in small groups for collaborative practice or used during independent practice. CWS also fosters the natural integration of language Arts and literacy with other content area curriculum standards.
Lights, Cameras, Pencils! Using Descriptive Video to Enhance Writing
Authors: Hoffner Helen , Baker Eileen , Quinn Kathleen Benson
Published: March 2008

Students of various ages and abilities can increase their comprehension and build vocabulary with the help of a new technology, Descriptive Video. Descriptive Video (also known as described programming) was developed to give individuals with visual impairments access to visual media such as television programs and films. Described programs, currently available on major television networks and in theaters, contain additional audio tracks that can be activated by using the Secondary Audio Program feature on a television, videocassette recorder, or DVD player. The description is intended to explain a program's highly visual elements (such as an actor's unusual costume or a car chase scene) to an individual with a visual impairment. Classroom research, however, suggests that descriptive programming can enhance comprehension and vocabulary for all students.
Prevention of Docetaxel- or Paclitaxel-Associated Taste Alterations in Cancer Patients with Oral Glutamine: A Randomized, Placebo-Controlled, Double-Blind Study
Authors: Strasser Florian , Demmer Ruth , Böhme Christel , Schmitz Shu-Fang Hsu , Thuerlimann Beat , Cerny Thomas , Gillessen Silke
Published: March 2008

Learning Objectives

After completing this course, the reader will be able to: Discuss the frequency, clinical presentation, and patient burden of taste alterations and peripheral neuropathy in patients receiving taxane-based chemotherapy.Identify the risk factors for developing peripheral neuropathy and taste alterations associated with taxanes.Administer glutamine treatment in the supportive care of peripheral neuropathy and taste alterations and evaluate emerging new agents.

CME Access and take the CME test online and receive 1 AMA PRA Category 1 Credit™ at CME.TheOncologist.com

Taste alteration (dysgeusia), an underrecognized toxicity associated with taxane-based chemotherapy (TaxCh), lacks standard treatment. We investigated prevention of dysgeusia with oral glutamine in patients undergoing first-time TaxCh.

Adult patients were randomized to receive either 30 g/day glutamine or placebo (maltodextrin) from day 1 of TaxCh. Dysgeusia was measured daily with a visual analogue scale (VAS). On each chemotherapy cycle, objective (sour, sweet, salty, bitter) and subjective (four-category scale) taste and toxicity (National Cancer Institute Common Toxicity Criteria, v.3) were assessed. Stomatitis and zinc deficiency were treated. For primary outcomes, repeated dysgeusia scores were analyzed with a linear mixed model. Repeated data on each objective or subjective taste item were analyzed with a generalized estimating equation.

Of 52 patients randomized, 41 completed treatment (median study duration, 74 days). At baseline, the glutamine (n = 21) and placebo (n = 20) groups were comparable for age (64 years), gender (32% men), tumor types, chemotherapy (docetaxel, 44%; paclitaxel, 56%), schedule (weekly, 78%; 3-weekly, 22%), treatment intention (15% adjuvant), dysgeusia (VAS, 11/100), and taste recognition (88%). Twenty-four patients had peripheral neuropathy grades 1–2; none had grade 3. Glutamine and placebo were not different for maximal dysgeusia and increase from baseline, with an insignificant linear time effect. Separate subgroup analyses for patients with baseline dysgeusia ≤11 or >11 did not alter the results. Objective or subjective taste tests were not different, neither were adverse events.

Compared with placebo, oral glutamine did not prevent or decrease subjective taste disturbances or altered taste perception associated with TaxCh. The role of glutamine in supportive care of taxane-associated dysgeusia seems limited.
The Clinical Approach Towards Chondrosarcoma
Authors: Gelderblom Hans , Hogendoorn Pancras C.W. , Dijkstra Sander D. , van Rijswijk Carla S. , Krol Augustinus D. , Taminiau Antonie H.M. , Bovée Judith V.M.G.
Published: March 2008

Learning Objectives

After completing this course, the reader will be able to: Classify the chondrosarcoma subtypes.Engage in the diagnostic process of chondrosarcoma.Evaluate the treatment options for chondrosarcoma.

CME Access and take the CME test online and receive 1 AMA PRA Category 1 Credit™ at CME.TheOncologist.com

This review provides an overview of the histopathology, classification, diagnostic procedures, and therapy of skeletal chondrosarcoma. Chondrosarcomas that arise de novo are primary chondrosarcomas, whereas chondrosarcomas developing superimposed on pre-existing benign cartilage neoplasms such as enchondromas or osteochondromas are referred to as secondary chondrosarcomas. Conventional chondrosarcomas can be categorized according to their location in bone into central, peripheral, and juxtacortical chondrosarcomas. Histological grading is related to prognosis; however, it is also subject to interobserver variability. Rare subtypes of chondrosarcoma, including dedifferentiated, mesenchymal, and clear cell chondrosarcoma, are discussed as well. Magnetic resonance imaging is necessary to delineate the extent of the intraosseous and soft tissue involvement preoperatively. Computed tomography is especially recommended in the pelvis and other flat bones where it may be difficult to discern the pattern of bone destruction and the presence of matrix mineralization. Wide, en-bloc excision is the preferred surgical treatment in intermediate- and high-grade chondrosarcoma. In low-grade chondrosarcoma confined to the bone, extensive intralesional curettage followed by local adjuvant treatment and filling the cavity with bone graft has promising long-term clinical results and satisfactory local control. Chondrosarcomas are relatively radiotherapy resistant; therefore, doses >60 Gy are needed in attempts to achieve local control after incomplete resection. Irradiation with protons or other charged particles seems beneficial in this curative situation. Chemotherapy is only possibly effective in mesenchymal chondrosarcoma, and is of uncertain value in dedifferentiated chondrosarcoma. Potential new systemic treatment targets are being discussed.
TRANSFORMATION OF AVOIDANCE RESPONSE FUNCTIONS IN ACCORDANCE WITH SAME AND OPPOSITE RELATIONAL FRAMES
Authors: Dymond Simon , Roche Bryaan , Forsyth John P. , Whelan Robert , Rhoden Julia
Published: March 2008

Research on the emergence of human avoidance behavior in the absence of direct contact with an aversive event is somewhat limited. Consistent with work on derived relational responding, the present study sought to investigate the transformation of avoidance response functions in accordance with the relational frames of Same and Opposite. Participants were first exposed to nonarbitrary and arbitrary relational training and testing in order to establish Same and Opposite relations among arbitrary stimuli. The training tasks were; Same—A1–B1, Same—A1–C1, Opposite—A1–B2, Opposite—A1–C2. Next, all possible combinatorially entailed (i.e., B—C and C—B) relations were tested. During the avoidance‐conditioning phase, one stimulus (B1) from the relational network signaled a simple avoidance response that cancelled a scheduled presentation of an aversive image and sound. All but one of the participants who met the criteria for conditioned avoidance also demonstrated derived avoidance by emitting the avoidance response in the presence of C1 and the nonavoidance response in the presence of C2. Control participants who were not exposed to relational training and testing did not show derived avoidance. Implications of the findings for understanding clinically significant avoidance behavior are discussed.
Convective Heat Transfer for Laminar, Steady-State Flow of Bingham and Power Law Fluids Between Vertical, Parallel Plates
Authors: Bayazitoglu Yildiz , Paslay Paul R. , Cernocky Paul
Published: March 2008

This paper explains how to model the convective heat transfer of Bingham and Power Law fluids across parallel plates. The analysis enables specification of the fluid properties necessary in order for Bingham or Power Law fluids to prevent or reduce convection and thus minimize Wellbore heat transfer. The paper gives the analytical, convective heat transfer flow solution for the Bingham material and Power Law fluids and uses this to determine example Nusselt numbers. The analysis is similar to the analysis by Batchelor for linear viscous fluids.

Applications are the reduction of heat transfer to minimize trapped annular pressures or to reduce heat loss from production fluids containing hydrates

The most important conclusion is that the influence of gel strength on convective heat transfer rate in oil industry applications is quite strong. Another conclusion is that the temperature differential required to initiate flow can be appreciable in practical applications, and this means the study indicates only a small gel strength should be sufficient to prevent convection. The gel strength does not need to be so large as to interfere with pumping. Another conclusion is a formulation for the way in which Power Law parameters influence convective heat transfer of the fluid, and hence identification of the parameters which need to be measured in order to characterize the convection of the fluid.
How Integrated Field Studies Help Asset Teams Make Optimal Field Development Decisions
Authors: Saputelli L. , Lujan L. , Garibaldi L. , Smyth J. , Ungredda A. , Rodriguez J. , Cullick A. S.
Published: March 2008

Developing an exploitation plan for an oil field has always been challenging. This paper presents different approaches and addresses the important question of how to allocate asset resources to maximize profit.

This study presents the analysis of integrated field case studies. Because of their complexities, integrated studies can offer valuable insights. Based on a field’s heterogeneity and complexity, it can be relevant to divide it into different investment units. Individual studies can be generated, and based on their results, different exploitation strategies can be visualized. The strategies are based on economic criteria, such as net present value and the efficient use of resources.

Capital investment efficiency is the key indicator that should direct resource allocation. Although there is no fixed method to find optimal decisions in a capital project, the FEL (front-end-loading) methodology measures and increases the level of project definition, thereby increasing the probability of project success at any stage of the life of the oil field. Traditionally, economic resources have been the principal metrics for analysis. However, the term resources encompasses many potential inputs to the system, e.g. drilling, facilities, enhanced recovery, and allocations.

In complex oil fields with many independent reservoirs, it has been found that each reservoir has its own characteristics. That leaves room to experiment on new combinations for development, such as infill drilling, injection in the most favorable reservoirs or new potentional drilling locations. In many cases, it was found that the oil price had the greatest impact on projects, because their profit margin is lower than the rest of field. Small reservoirs or reservoirs that require marginal investment show the highest efficiency in investment, which means that investment efficiency is inversely related to the total amount of investment. This finding indicates that focusing solely on investment efficiency can mislead the optimal decision.
Pulsed Neutron Logging through Multiple Casings
Authors: Desport O. , Crowe J.
Published: March 2008

The success of a production enhancement program relied on the use of cased hole logs to determine gas/oil contacts and oil/water contacts in several key reservoirs. There was a major obstacle to success: the clastic reservoirs were drilled with 12-1/4 inch wellbore, and completed with two centralized casings (9-5/8 inch and 7 inch) and a single tubing string.

Pulsed neutron (sigma and carbon/oxygen) is not characterized for such a completion; however, no other technique could possibly identify contacts through the multiple casing/tubing. Rather than waiting for the tubing to be pulled out, the decision was taken to run the pulsed neutron from a barge prior to a rig moving onto the location as an attempt to detect critical gas/oil, and hopefully oil/water contacts in several key reservoirs.

This paper discusses the logging sequence and the various challenges encountered, both in terms of measurement and interpretation (data statistics, depth of investigation, sigma computation, carbon/oxygen interpretation in uncharacterized environment). The planning of the logging operations clearly showed that detection of the formation through the tubing and dual centralized casing would be extremely difficult, a risk that was accepted. The results show that a signal from the formation was acquired and the contacts were identified with confidence and made possible an optimization of the perforating intervals. A possible reason for the success of the logging is that the information indicating that both casings were both centralized may be incorrect.
Casing Fatigue Life Prediction Using Local Stress Concept: Theoretical and Experimental Results
Authors: Teodoriu C. , Ulmanu V. , Badicioiu M.
Published: March 2008

Local stress/strain concept analysis using material properties for low-cycle fatigue can accurately predict fatigue life of casing strings exposed to variable loads. Standard approaches that assume only static loads ignore the variations in temperature and pressure that affect loads on casing strings during steam injection or in geothermal wells and lead to inaccurate estimates of fatigue life. Full-scale experimental results show that our method properly accounts for these variations, reducing time and cost in fatigue life prediction. Our method can be extended to any type of fatigue in which large deformations occur.
Reservoir Pressure Management Using Waterflooding: A Case Study
Authors: Phade Anish , Gupta Yash
Published: March 2008

As a rule, the reservoir pressure depletion occurs with a continuous production over a period of time. This leads to high Gas-Oil Ratio and low production rates. Thus it is important to manage the pressure of reservoir and stabilize it. For this, certain IOR techniques are employed; waterflooding being one of them. This paper discusses waterflooding as a solution for a pressure management program. This work represents results of the strategic IOR program in a mature field showing importance and influence of each decision made during project implementations.

The reservoir into consideration is a sandstone reservoir which was producing under a solution gas drive & a very weak aquifer for about 5 years. During the course of production, reservoir pressure decreased substantially and went below the bubble point pressure. Waterflooding was considered as the most suitable remedy to restore the reservoir pressure and well productivity, considering all the parameters. Various waterflooding plans were designed on the basis of areal & vertical sweep efficiencies and reservoir voidage compensation using material balance. The fractional flow, saturation profiles, mobility ratio and frontal advance equations were kept in mind while proposing these plans.

By implementation of the most appropriate plan, the reservoir pressure was maintained 150 psi above the bubble point pressure resulting in daily production rate of about 13000 bopd with water injection rate of about 15000 bpd. The estimated oil recovery is about 52 % and breakthrough is expected to occur about 7 years after the start of waterflood. The results were not only a total reversion but also an increasing production profile that was declining over the years.
Long-Term Evaluation of Low-Density Cement, Based on Hollow Glass Microspheres, Aids in Providing Effective Zonal Isolation in HP/HT Wells: Laboratory Studies and Field Applications
Authors: Al-Yami A. S. , Nasr-El-Din H. A. , Al-Arfaj M. K. , Al-Saleh S. H. , Al-Humaidi A. S. , Al-Shuker N. A.
Published: March 2008

Cementing a string in one stage is a challenging task, especially in the presence of weak formations. Cement slurry losses during placement is highly possible if the equivalent circulating density (ECD) exceeds 11 lb/gal during placement. A conventional method to overcome this challenge is to use multi-stage cementing by setting the stage tool above the loss circulation zone. However, field data indicate that the tool can fail, thus causing serious delay and economic loss. A second method for zonal isolation is to use low density cement.

In this study, we considered cementing the intermediate and production casings in HP/HT BJD formation (dolomite) in a single stage using low density cement that was based on hollow microspheres at 9.35 lb/gal. The objective of this work was to compare hollow microspheres cements to bentonite cements, which are used in multistage cementing. The tests included shrinkage, compressive strength, porosity, gas, and brine permeability. There are potential hole problems that were faced while drilling for the casing point in BJD. These problems included water flow, which might contain H2S. This problem will require good cement durability to provide zonal isolation.

The total vertical depth (TVD) of the casing point in BJD was ± 10,000 ft and the mud density was ± 9.09 lb/gal. Testing conditions were temperature of 260°F, crushing pressure of 5,000 psi, and a confining pressure of 3,000 psi. No work was done before to investigate hollow microspheres cements at these conditions. The testing was performed in Saudi Aramco facilities to improve current cementing practices in oil and gas fields.

Data generated during three months supported the use of the hollow microspheres to cement casings at the conditions tested. The compressive strength did not change significantly with an average of 1,400 psi; neither shrinkage nor liquid permeability did change during the testing period.

This paper will discuss case histories that include job design, execution, and evaluation of the low density cement system. Field treatments were conducted without encountering any operational problems. The treatments were successful, which confirmed lab data.
Oil-Microbe Detection Tool Using Nano Optical Fibers
Authors: Jahagirdar Shruti Ravindra
Published: March 2008

Most reservoirs at some point in their life are candidates for Enhanced Oil Recovery (EOR). Successive to microbial enhanced oil recovery (MEOR) when reservoir is put on waterflooding, water cut greater than 80% is observed after sometime. Then either a second round of MEOR is planned or the well is abandoned. Another round of MEOR takes at least six months, is expensive and complicated than waterflooding. The proposed tool will assist in detecting the bypassed oil after a cycle of MEOR and help make the best choice of recovery method to be used next, namely MEOR or waterflooding.

The tool will work on the principle of Resonance Raman Spectroscopy (RRS). Since the microbes used in MEOR are exactly known, their response to RRS on the surface can be tested and the same response from inside the reservoir can be noted. In this way the microbes can be detected downhole by the Resonance Raman spectra which they exhibit. The microorganism detection is based on identification and excitation of chemotaxonomic markers present in them. Since microbes only survive on the oil-water interface wherever microbes will be detected, it is clear that oil is still present in that region. This depth will be sensed using depth sensor. Water being Raman inactive, at whatever depth thief zones of water are formed no spectrum will be observed and these zones can be detected and plugged thus deviating water to oil-bearing zones. The tool will be lowered downhole by optical fibers which can also transmit the reflected light to a computer on the surface to view the spectra. The nano optical fibers will penetrate the formation and carry the laser light in porous rock matrix and receive the reflected light.

The tool can also identify different microorganisms present in reservoir. This helps in knowing the reservoir parameters like temperature, pressure, salinity etc, since every type of microbe has a particular environment in which it can survive. When waterflooding is done after any other thermal or chemical recovery process the tool can track oil instead of microbes directly by sensing H-C, H=C etc. bonds present in oil.
A New Diagnostic Analysis Method for Waterflood Performance
Authors: Yang Zhengming
Published: March 2008

Despite the widespread application of reservoir simulation to study waterflood reservoirs, petroleum engineers still need simple predictive tools to forecast production decline,estimate ultimate oil recovery, and diagnose the production performance from the historical field data.

Based on the Buckley-Leverett equation and the assumption of a semi-log relationship between relative permeability ratio and water saturation(kro/km=Ae−BSW, where Aand Bare constants),a consistent analytical solution can be derived as qoD(1−qoD)=(EVB)1tD, where qoD is the oil fractional flow,tD is the fraction of cumulative liquid production to total formation volume PV, and EV is the volumetric sweep efficiency. Two equivalent linear plots can be developed: a log-log plot and a reciprocal time plot. The log-log plot has a slope of -1 and intercept of EV/B. The reciprocal time plot has a slope of EV/B and an intercept value of 0.

Both plots can be applied for the diagnostic analysis of waterflood reservoirs.

Model and field case studies show the benefits of this technique as a production decline analysis tool in forecasting the waterflood production decline and the ultimate oil recovery. This method can also be applied as a diagnostic tool to evaluate various aspects of waterflood performance. Examples include assessing waterflood maturity, calculating volumetric sweep efficiency, distinguishing the normal waterflood breakthrough from the premature water breakthrough through hydraulic fractures, and examining the consequences of operational changes. The appropriate use of this analytical method will help to optimize the field waterflood operation.
Use of Transient Data to Calculate Absolute Permeability and Average Fluid Saturations
Authors: Kamal Medhat M. , Pan Yan
Published: March 2008

A new well testing analysis method is presented. The method allows for calculating the absolute permeability of the formation in the area influenced by the test and the average saturations in this area. The method applies to two-phase flow in the reservoir (oil and water or oil and gas). Future expansion to three-phase flow is possible. Current analysis methods yield only the effective permeability for the dominant flowing phase and the "total mobility" of all phases. The new method uses the surface flow rates and fluid properties of the flowing phases and the same relative permeability relations used in characterizing the reservoir and predicting its future performance. The method has been verified by comparing the results from analyzing several synthetic tests that were produced by a numerical simulator with the input values. Use of the method with field data is also described.

The new method could be applied wherever values of absolute permeability or fluids saturations are used in predicting well and reservoir performance. Probably the major impact would be in reservoir simulation studies where the need to transform well testing permeability to simulator input values is eliminated and an additional parameter (fluids saturations) becomes available to help history match the reservoir performance. This work will also help in predicting well flow rates and where absolute permeability changes with time (e.g., from compaction).

Results showed that the values of absolute permeability in water-oil cases could be reproduced within 3% of the correct values and within 5% of the correct values in gas-oil cases. Errors in calculating the fluid saturations were even less. One of the main advantages of this method is that the relative permeability curves used in calculating the results and later on in using the results are the same ensuring consistent process.

The impact of this study will be to expand the use of the information already contained in transient data and surface flow rates of all phases. The results will provide engineers with additional parameters to improve and speed up the prediction of well and reservoir performances in just about all studies.
Research and Application of Mathematical Model for Foam Diversion Acidizing
Authors: Li Songyan , Li Zhaomin , Lin Riyi , Li Binfei
Published: March 2008

Foam diversion can effectively solve the problem that acid distribution among layers of different permeability is uneven during matrix acidizing. Based on gas trapping theory and mass conservation equation, mathematical models for foam slug diversion acidizing and foamed acid diversion acidizing were established. Design method for foam slug diversion acidizing was given. The mathematical models were solved by computer program. The results show that total formation skin factor, and pressure of wellhead and bottomhole increase with foam injection, and decrease with acid injection. Volume flow rate of high-permeability layer decreases, and that of low- permeability layer increases during foam injection, which can divert subsequent acid to low-permeability layer from high-permeability layer. Under the same formation situation, the effect of foamed acid diversion acidizing is better than foam slug diversion acidizing. In foamed acid diversion acidizing process, operation time is longer, and pressure of wellhead and bottomhole is higher. Field application shows that foam slug diversion acidizing can effectively block high permeability layer, and improve intake profile obviously. It is fit to acidizing for heterogenous formation.
Direct Current Electrical Enhanced Oil Recovery in Heavy-Oil Reservoirs To Improve Recovery, Reduce Water Cut, and Reduce H2S Production While Increasing API Gravity
Authors: Wittle J. K. , Hill D. G. , Chilingar G. V.
Published: March 2008

Electro-Petroleum, Inc. (EPI) has successfully demonstrated use of DC electrical current for enhanced oil recovery (a process we now call "Electro-Enhanced Oil Recovery", or EEOR) at heavy oil fields in the Santa Maria (California) Basin and the Eastern Alberta Plains. They have also conducted large-scale (1 cu-m sample size) laboratory studies to evaluate unexpected results from these field demonstrations.

Dr. G. V. Chilingar, of the University of Southern California, publicly advocated using a similar technology in the 1960’s. Several successful applications of similar technology have been claimed, in the Former Soviet Union.

Field studies in California have demonstrated up to a ten-fold increase in oil production from a field containing 8° API gravity oil. Recent research has demonstrated that the EEOR process is also capable of cold cracking of heavy oil in-situ, resulting in lighter produced oil and increased reservoir pressures. EEOR can function at depths below 10,000 feet, well below the 2,500 ft. practical limit for steam flood operations. Observed changes in the produced fluids include:Increased oil production rates.Reduced produced oil viscosity increased API gravity).Reduced water cut.Reduced H2S production.Increased gas production.Increased produced gas energy (heavy gas) content.Reduced PAH production.

All of these observed fluid chemistry changes can be explained by the use of DC electrical technology.
A Quadratic Cumulative Production Model for the Material Balance of an Abnormally Pressured Gas Reservoir
Authors: Gonzalez F. E. , Ilk D. , Blasingame T. A.
Published: March 2008

The premise of this work is the concept, development, and application of an approximate relation for the material balance of abnormally pressured gas reservoirs. In particular, the proposed approximation is formulated directly from the rigorous material balance for the case of an abnormally pressured gas reservoir. Our "quadratic cumulative production" result is given by: (1)pz≈pizi[1−[1G−ω]Gp−ωGGp2]

where ω is defined as a function ofGp

The ω-function is defined by the "cumulative effective compressibility" [ c¯e (p)] and represents the influence of abnormal pressure. If we assume ω =constant (but this does not mean that c¯e (p) is constant), then we obtain the "quadratic" formml: (2)pz≈pizi−αGp−βGp2whereα=1G−ωandβ=ωG

Eq. 2 is the base definition of the "quadratic cumulative production" relation (ω is constant; therefore, α and β are constant). We have shown this relation to be an extraordinarily accurate approximation of the rigorous material balance for the case of a dry gas reservoir with abnormal pressure effects.

Eq. 2 is suited not only for use as a characteristic model, but also for use as a data analysis mechanism (i.e., in this work we use Eq. 2 to develop a suite of analysis plots, plotting functions, a type curve, etc.). We also address the case of ω being a linear function of Gp (as opposed to ω being constant) — which results in a formulation where p/z is cubic in terms of Gp.

In this work, we provide the following new results: The "quadratic cumulative production" model for the material balance behavior of abnormally pressured gas reservoir.A suite of 6 (six) plotting functions based on the p/z-G2 material balance model.A suite of 4 (four) ω-Gp performance plots which are used to calibrate the analysis process.A new type curve pD[=(pi/zi-p/z)/pi/zi] versus GpD[=Gp/G], based on the new p/z-G2 material balance model.

Objectives

The primary objectives of this work are:
Optimized Foam Drilling Improves Drilling Performance in Iranian Carbonate Fields
Authors: Shirkavand F. , Hareland G. , Teichrob R. , Haeri Behbahani S. M.
Published: March 2008

The advantages of foam drilling over conventional mud drilling have long been recognized and include faster penetration rates, longer bit life, prevention of lost circulation and less formation damage to the producing reservoir resulting in overall drilling cost reduction and higher production rates. Careful practical design and control of gas and liquid volumes, injection pressure and annular backpressure must be applied in foam drilling to achieve the optimum results. Optimization of foam drilling is done by drilling with the lowest acceptable bottom hole pressure and making sure that the wellbore is kept clean. This is done by applying an integrated flow model that accounts for both the compressibility of the foam, the hydrostatic column and the frictional pressure losses in conjunction with minimum hole cleaning requirements. The model is integrated with the hole cleaning requirements to obtain the balanced and lowest bottom hole pressure for the operation. The equations, procedure and sample application of this method are presented herein. Using this UBD approach on Iranian oil fields indicates large cost savings. The drilling operations in the Shanoul and Parsi fields shows as much as 60-70 percent reduction in bottom drilling time using foam drilling compared to conventional mud drilling. Using the optimum volumetric model for foam drilling and a series of simplified hole cleaning charts presented herein, the foam drilling program for the Shanoul field enabled determination of optimum drilling and hole cleaning parameters in this field. This paper presents results from programming of near balanced conditions using a new foam drilling program designed for the Shanoul field. The target formations were hard, fractured and depleted limestone formations with low pressure. The paper also compares the results to similar wells drilled with aerated fluids and conventional muds, which indicates the foam drilling as being superior in terms of rate of penetration longer bit life and less wellbore instability. A drilling cost study comparing conventional, aerated and foam drilling is also presented.
The Effect of Geologic Parameters and Uncertainties on Subsurface Flow: Deepwater Depositional Systems
Authors: Milliken William J. , Levy Marjorie , Strebelle Sebastien , Zhang Ye
Published: March 2008

The application of reservoir simulation as a tool for reservoir development and management is widespread in the oil and gas industry. Moreover, it is recognized that the results of any reservoir simulation model are strongly influenced by the underlying geologic model. However, the direct relationship between geologic parameters and subsurface flow is obscure. In this paper we explore this relationship in a deepwater depositional system using data from two reservoir analogs: the shallow seismic dataset from the Mahakam Fan and outcrop data from the Brushy Canyon Formation of West Texas.

Shallow seismic data from the Mahakam Fan area shows a high-resolution deepwater channel-levee system consisting of 10 migrating channels. Using an experimental design framework and a series of three increasingly complex models, we investigated the effect of nine different geologic factors on several different measures of the flow behavior. Our results show that, as expected, different geologic factors influence different measures of the flow. Most significant is the clear effect that the proportion and organization of the different internal facies making up the channels have on the recovery factor and net oil production.

The Brushy Canyon outcrops used in this work represent sand-rich proximal deposits of a distributary lobe complex. Here we built models on a very small length scale to investigate the effects of sheet-like reservoir architecture as well as internal facies distribution of the sheets on subsurface flow. Again, an experimental design framework was employed, this time to examine the influence of 11 input variables. The proportion and organization of the internal lobe facies has a significant influence on the subsurface flow here but in these distributary lobe complexes other variables, including the stacking of the lobes, were also found to be important.

The models in this study address flow behavior in deepwater, sparse well environments. Using models from the simple to the complex, we found that several parameters incorporated in the complex models, and not in simple models, had a significant impact on the predicted flow.
Reliability of Multiphase Flowmeters and Test Separators at High Water Cut
Authors: Ojukwu Kelechi Isaac , Edwards John
Published: March 2008

The use of multiphase flowmeters (MPFM) for well test measurements is increasingly becoming a standard practice replacing conventional test separators. These MPFMs are usually tested and calibrated in laboratory controlled flow loops using idealized fluids in steady state conditions. However for high water-cut, high gas-volume-fraction and low pressure unstable flow these controlled conditions are far from reality which can lead to unforeseen errors in the field. Recent experience shows that in certain conditions, the various types of multiphase flowmeters react quite differently to the measurement challenges of transient flows in high water cut and high gas volume fractions (GVF). Some meters can be unreliable in measuring oil rates in certain conditions which leads to inaccurate estimation of the wells' potential and associated uncertainty in plans for production optimization. For example the inaccuracies in measured oil rates could be greater than the gain expected from a stimulation or restoration. An inaccurate measure of oil rate also leads to a poor reconciliation factor and poor estimation of reserves. By resolving these inaccuracies and allocating oil correctly to wells it is possible to invest in right opportunities thereby saving unnecessary expenditure. The factors that affect multiphase flowmeter measurement can range from excessive gas-volume-fraction, low line pressures, solids and unsteady flow.

In 2007 an in-situ comparison was made of two types of multiphase flow meters and two separators to determine the most appropriate well test device for X Field in the Sultanate of Oman. X Field wells are artificially lifted and have a high water cut of 80%. The reconciliation factor (also known as the back allocation factor) before this well test campaign was 0.54. The comparison was made on twelve wells producing to X Field station. Each well was tested for 12 hours in series using an existing inline MPFM, a low pressure production test separator, a second mobile MPFM, a 1440psi separator, and a multiphase tracer technique. The objective to determine the most reliable technique(s) of measuring oil production rates was accomplished, and now the reconciliation factor is 1.03. This paper describes the comparison, how the results were analyzed, and the comparative error associated with each technique.
Quantitative Analysis of Mud Losses in Naturally Fractured Reservoirs: The Effect of Rheology
Authors: Majidi R. , Miska S. Z. , Yu M. , Thompson L. G.
Published: March 2008

Significant fluid loss while drilling through fractured formations is a major problem for drilling operations. From field experience we know that the type and rheological parameters of the drilling fluid have a strong impact upon the rate and volume of losses.

In this work, a mathematical model for flow of Yield-Power-Law (Herschel-Bulkley) fluids in fractures is presented. The governing equation is derived using the principles of conservation of mass and linear momentum for transient radial flow in a fracture. Results are obtained based on numerical solutions and plotted in terms of mud loss volumes versus time for a given drilling fluid under certain operational conditions. Results show how the rheological properties of drilling fluid such as yield stress and flow behavior index ( shear-thinning/thickening effect), influence mud losses in fractured formations. According to this model the yield stress of drilling fluids tremendously decreases the potential for mud losses. The effect of yield stress on reducing mud losses is the same as the effect of overbalance pressure on increasing losses. The shear thinning effect of drilling fluids can also greatly increase the rate of losses. Therefore, mud losses in fractures can be minimized by properly optimizing the rheology of the drilling fluid.

Using this model, quantitative analysis of losses that take into account fluid rheology in order to characterize the fracture can be achieved. One can obtain the hydraulic aperture of conductive fractures by continuously monitoring mud losses and fitting field records of mud losses to the model. For general applications, type-curves are provided that describe drilling fluid loss of Yield-Power-Law fluids into fractures. Newtonian, Bingham Plastic and Power Law fluids are special cases. The proposed model is very useful not only for drilling applications but also for well completion design and fractured reservoir characterization.

Field data measurements are used to demonstrate the practical application of the proposed technique. Good agreement between the model and field data confirms the validity and applicability of the model.
The Study and Application of Fracturing Optimization Technology for Complicated Fault Block Reservoir With Strong Water Sensitivity
Authors: Li Yongming , Guo Jianchun , Yue Yingchun , Zhao Jinzhou , Guo Cunyong
Published: March 2008

S83 reservoir in north China is characterized with abundant faults, strong heterogeneity, medium porosity, medium or low permeability and strong water sensitivity. So its natural production is very low, and hydraulic fracturing is the valid means to enhance production. However, low proppant amount, low average ratio of proppant to fluid, the damage of fracturing fluid and proppant embedment made the previous stimulation effect indistinct. For this reason, we carried on the research into low damage fracturing technology based on the characteristics of S83 reservoir and acquired prominent stimulation effect through field application. This paper presents the research and field application in this reservoir.

Firstly, use reservoir simulation software to optimize fracture parameters of oil wells with or without corresponding water injection wells and to determine fracturing scale. Secondly, do some indoor experiments including rock mechanical test, proppant embedment test and so on, and develop the fracturing fluid with low friction and low damage for S83 reservoir through additive selection. Based on the necessity analysis of enhancing fracture conductivity and combined with the present situation analysis of high conductivity fracturing technology, the low damage fracturing strategy for S83 reservoir is proposed and fracturing design principles of high sand concentration, low fluid amount, fracture length control, strengthening conductivity and low damage are determined. The research results have been used in 2 wells and their postfrac production rose to more than 10m3/d from less than 0.5m3/d before fracturing. The stimulation effect is very prominent. From the results we can conclude that low damage fracturing technology is reasonable and feasible, which presents a new practical fracturing technology for strong water sensitivity formations and has guiding significance for similar reservoirs.