bluuebunny/crossref_metadata_2025_split huggingface dataset:
State-of-the-Art in Coalbed Methane Drilling Fluids
Authors: Baltoiu Len V. , Warren Brent K. , Natras Thanos A. 
Published: September 2008

Summary
The production of methane from wet coalbeds is often associated with the production of significant amounts of water. While producing water is necessary to desorb the methane from the coal, the damage from the drilling fluids used is difficult to assess, because the gas production follows weeks to months after the well is drilled. Commonly asked questions include the following:
What are the important parameters for drilling an organic reservoir rock that is both the source and the trap for the methane? Has the drilling fluid affected the gas production? Are the cleats plugged? Does the "filtercake" have an impact on the flow of water and gas? Are stimulation techniques compatible with the drilling fluids used?
This paper describes the development of a unique drilling fluid to drill coalbed methane wells with a special emphasis on horizontal applications. The fluid design incorporates products to match the delicate surface chemistry on the coal, a matting system to provide both borehole stability and minimize fluid losses to the cleats, and a breaker method of removing the matting system once drilling is completed.
This paper also discusses how coal geology impacts drilling planning, drilling practices, the choice of drilling fluid, and completion/stimulation techniques for Upper Cretaceous Mannville-type coals drilled within the Western Canadian Sedimentary Basin. A focus on horizontal coalbed methane (CBM) wells is presented.
Field results from three horizontal wells are discussed, two of which were drilled with the new drilling fluid system. The wells demonstrated exceptional stability in coal for lengths to 1000 m, controlled drilling rates and ease of running slotted liners. Methods for, and results of, placing the breaker in the horizontal wells are covered in depth.
An Alternative to Sand-Control Screens: Is Permeable Cement a Viable Option?
Authors: Vidick Benoit , James Simon , Drochon Bruno 
Published: September 2008

Summary
The search for a cost-effective alternative to screens has been intensive in the sand-control field. Different systems have been proposed in the past, including various solutions based on permeable cement, but none of them have made a real breakthrough.
This paper presents a new permeable-cement system that has significant advantages over previous systems. In particular, this permeable cement was formed in a one-stage process, eliminating the need for a subsequent treatment to generate permeability. This permeable-cement system also has adequate strength and sufficient permeability for several sand-control applications. However, the durability of the permeable cement was evaluated and found to be poor. Some suggestions are made for possible applications of the permeable cement for both primary and remedial sand-control applications.
Kikeh Batch Setting: Case Study
Authors: Flannery Chris , Choo Benjamin 
Published: September 2008

Summary
The semisubmersible rig Ocean Rover was used by Murphy Sabah Oil Company to batch-set 23 wellheads in 4,350-ft-deep water with zero health, safety, and environment (HSE) incidents.
The batch-set team worked to maintain safety and performance and to overcome numerous logistical and operational challenges. Implementing lessons learned and development of recommended practices resulted in continuous improvement throughout the project.
The program was completed in 63 days. The average installation time for conductor and surface casing was 3.36 days from start to finish. Total materials used were 50,000 ft of casing, 3,060 tonnes of cement, and 78,000 bbl of 16.6 lbm/gal dynamic kill drilling (DKD) mud.
Improving Formation-Strength Tests and Their Interpretation
Authors: van Oort Eric , Vargo Richard 
Published: September 2008

Summary
Verifying pressure integrity of a casing string and the adjacent formation is an important requirement during drilling of a well. Crucial decisions on mud weight, kick tolerance, and the setting depth of the next casing string are based on the outcome of formation-strength tests (FSTs) such as leakoff tests (LOTs) or formation-integrity tests (FITs). Moreover, government regulations usually require that a minimum integrity is guaranteed before a well may be deepened.
Yet the majority of FSTs and their interpretations currently carried out in the field can only be characterized as inadequate. Commonly, FSTs lack quality and accuracy because of insensitivity in the hydraulic system to subtle pressure effects in the wellbore, use of highly compressible synthetic or oil muds, nonlinear thermal profiles, poorly understood formation-stress and -strength behavior, or simply because of poor data capturing (e.g., by using hand-generated plots). This may have a significant negative impact on the drilling operation. For instance, when mud-weight windows are assessed incorrectly after testing, lost circulation or well-control problems may ensue on wells with tight drilling margins.
Here, we highlight several of the problems underlying current FSTs and their interpretations, illustrating them with actual field examples [such as the discrepancy often observed between surface readings and downhole pressure-while-drilling (PWD) readings obtained while testing], and show how test artifacts can be either avoided or accounted for. A case is made for the use of downhole recorded pressure data to determine casing-shoe strength correctly.
A New Skin-Factor Model for Perforated Horizontal Wells
Authors: Furui K. , Zhu D. , Hill A. D. 
Published: September 2008

Summary
Using a combination of analytical calculations and 3D finite-element simulation, we have developed a comprehensive skin-factor model for perforated horizontal wells. In this paper, we present the mathematical model development and validation by comparison with finite-element simulation results. With the new perforation skin model, we then show how to optimize horizontal well perforating to maximize well productivity.
A cased, perforated well may have lower productivity (as characterized by a positive skin factor) relative to the equivalent open-hole completion because of two factors: the convergence of the flow to the perforations, and the blockage of the flow by the wellbore itself. Because of the orientation of a horizontal well relative to the anisotropic permeability field, perforation skin models for vertical wells that consider these effects, notably the Karakas and Tariq model (1991), are not directly applicable to perforated horizontal completions. Using appropriate variable transformations, we derived a skin-factor model for a horizontal perforated completion that is analogous to the Karakas and Tariq (1991) vertical-well model. The empirical parameters in the model were determined from an extensive 3D finite-element simulation study.
The results of the new model show that the azimuth of a perforation (the angle between the perforation tunnel and the maximum permeability direction, usually thought to be in the horizontal direction) affects the performance of perforated completions in anisotropic reservoirs. When perforations are normal to the maximum-permeability direction, perforations will enhance horizontal-well flow compared with an openhole completion (a negative skin factor). But if perforations are in the same direction as the maximum permeability, significant positive skin will result. The new skin-factor model provides a clear guide to the shot density, perforation orientation, and level of perforation damage that is tolerable to create high-productivity perforated completions in horizontal wells.
Geomechanics Aspects of Multiple Fracturing of Horizontal and Vertical Wells
Authors: Soliman M. Y. , East Loyd , Adams David 
Published: September 2008

Summary
Although unstimulated horizontal wells have1 been successful in naturally fractured reservoirs and in reservoirs with gas- or water-coning problems, fracturing a horizontal well may be a viable option in certain situations. Because of the dependence of fracture orientation on well direction with respect to the stress field, the possibility of fracturing a horizontal well must be considered before the well is drilled. The appropriate contingency plans should be made to anticipate the possible low production from an unstimulated well. It should be remembered that fracturing a horizontal well may also dictate how the wellbore may be completed or oriented. Fracturing a horizontal well may take place in one of the following situations:
Restricted vertical flow caused by low vertical permeability or the presence of shale streaks. Low formation productivity because of low formation permeability. The presence of natural fractures in a direction different from that of induced fractures. Thus, induced fractures have a high chance of intercepting the natural fractures. Low stress contrast between the pay zone and the surrounding layers. In this case, a large fracturing treatment of a vertical well would not be an acceptable option because the fracture would grow in height as well as length. Drilling a horizontal well and creating either several transverse or longitudinal fractures would allow rapid depletion of the reservoir through the fractures.
Although fundamentally similar to fracturing vertical wells, fracturing horizontal wells has its unique aspects that require special attention to secure successful treatment. Differences between horizontal and vertical wells exist in areas of rock mechanics, reservoir engineering, and operational aspects. To start with, the basic rock-mechanics aspects are examined.
Hole Cleaning During Underbalanced Drilling in Horizontal and Inclined Wellbore
Authors: Zhou L. 
Published: September 2008

Summary
This paper is an extended work of SPE 90038. An aerated non-Newtonian flow and an inclined wellbore section were added to the previous model to study the hole-cleaning problem while drilling an underbalanced well. This new mechanistic model for cuttings transport was developed by combining two-phase hydraulic equations, turbulent boundary layer theory, and particle transport mechanism. It is shown that the model is useful for predicting minimum annular velocity and cuttings bed thickness in horizontal and inclined wellbore geometry. Effects of temperature, bottom hole pressure, liquid flow rate, gas injection rate, cuttings size and density, inclination angle, and rheological properties of drilling mud on hole cleaning are analyzed using this mechanistic model. The model is validated by available experimental data. Computer simulation indicates that cuttings bed thickness is very sensitive to the liquid phase flow rate. It dominates cuttings transport efficiency. However, during underbalanced drilling, increase of liquid phase fraction may not always be feasible while trying to keep a low equivalent circulating density (ECD). Meanwhile, injection of gas has positive effects on cuttings transportation depending on the flow patterns and drilling mud viscosity. Elevated temperature causes a significant increase of bed thickness, and it is important to recognize this negative effect, especially when drilling high-pressure/high-temperature (HPHT) wells. The effect of pressure on cuttings concentration is negative. Larger size and heavier cuttings make hole cleaning more difficult and require higher pump rates for low-viscosity fluids. Increases of liquid phase density result in better hole cleaning. The range of hole angles from approximately 35° to 60° (from vertical) is the most difficult for cuttings transport. Frictional pressure losses in a deviated wellbore highly depend on cutting bed thickness. Simulation results are compared to available experiment data and show good agreement. In summary, this paper presents a model that is useful for practical hole cleaning during underbalanced drilling (UBD).
A New Method of Producing Laterally Stable PDC Drill Bits
Authors: Johnson S. 
Published: September 2008

Summary
Bit whirl is well documented as a major cause of damage to polycrystalline-diamond-compact (PDC) drill bits and results in short runs, low rate of penetration (ROP), high cost per foot, poor hole quality, and downhole-tool damage. Hence, consistent lateral stability is highly desirable in PDC bits.
This paper presents a new method of producing PDC drill bits that reduce or eliminate bit whirl. Traditionally, attempts to design laterally stable PDC bits have assumed that the forces generated by the bit during stable drilling cause it to begin whirling. The new approach assumes that it is the response of the bit to forced motion off its center that causes whirl.
The new approach has been validated theoretically, in the laboratory, and in the field. Test results from a full-scale drilling rig indicate that this method is superior to existing methods at minimizing bit whirl.
This new method was validated successfully through an extensive field-test program undertaken in the northwest USA, involving high-speed downhole measurements from both conventional 7⅞-in.-diameter PDC drill bits and bits designed using this new method. The results demonstrated that the conventional PDC drill bits exhibited bit whirl throughout the run. The bits designed using the new method eliminated bit whirl completely.
The performance benefits of this new method were demonstrated in a 16-in.-bit section in a Middle Eastern field, where lateral vibrations are a significant problem. Before testing the new-method PDC bit, bit optimization led to the use of high imbalance force designs to minimize lateral vibration. The first test of the new method laterally stable PDC bit set field records for ROP, footage, and cost per foot compared with more than 50 runs with "antiwhirl" (Warren et al. 1990) designs, resulting in savings of more than USD 50,000 per run.
This paper demonstrates how use of the new method can eliminate whirl in both laboratory and field environments and deliver significant performance improvements over existing stability techniques.
This new method represents a significant step forward in the design of PDC bits to mitigate bit whirl, and it has been proved to reduce bit damage, increase run lengths, increase ROP, and deliver sizeable savings for operators.
Efficacy and Safety of the Dipeptidyl Peptidase-4 Inhibitor Alogliptin in Patients With Type 2 Diabetes and Inadequate Glycemic Control
Authors: DeFronzo Ralph A. , Fleck Penny R. , Wilson Craig A. , Mekki Qais ,   on behalf of the Alogliptin Study 010 Group
Published: September 2008

OBJECTIVE—To evaluate the dipeptidyl peptidase-4 (DPP-4) inhibitor alogliptin in drug-naïve patients with inadequately controlled type 2 diabetes.
RESEARCH DESIGN AND METHODS—This double-blind, placebo-controlled, multicenter study included 329 patients with poorly controlled diabetes randomized to once-daily treatment with 12.5 mg alogliptin (n = 133), 25 mg alogliptin (n = 131), or placebo (n = 65) for 26 weeks. Primary efficacy end point was mean change from baseline in A1C at the final visit.
RESULTS—At week 26, mean change in A1C was significantly greater (P &lt; 0.001) for 12.5 mg (−0.56%) and 25 mg (−0.59%) alogliptin than placebo (−0.02%). Reductions in fasting plasma glucose were also greater (P &lt; 0.001) in alogliptin-treated patients than in those receiving placebo. Overall, incidences of adverse events (67.4–70.3%) and hypoglycemia (1.5–3.0%) were similar across treatment groups.
CONCLUSIONS—Alogliptin monotherapy was well tolerated and significantly improved glycemic control in patients with type 2 diabetes, without raising the incidence of hypoglycemia.
The spectrum of adult B‐lymphoid leukemias with BCR‐ABL: Molecular diagnostic, cytogenetic, and clinical laboratory perspectives
Authors: Klco Jeffery M. , Kreisel Friederike H. , Zehnbauer Barbara A. , Kulkarni Shashikant , Hassan Anjum , Frater John L. 
Published: September 2008

AbstractThe Philadelphia (Ph) chromosome is characteristic of chronic myelogenous leukemia (CML), but it is also the most frequent cytogenetic abnormality in precursor B‐lymphoblastic leukemia (ALL) of adults. The vast majority of CML patients have a BCR‐ABL translocation that yields a 210 kD (p210) oncoprotein, whereas adult Ph‐positive ALL cases can present with either a p190 or a p210 oncoprotein, or both. Considering that 30% of the patients with CML that progress to blast crisis will have a lymphoblastic presentation, adults presenting with a p210 ALL may have either a de novo ALL or CML presenting for the first time in lymphoblastic phase. To identify the distinguishing features, cases of p190‐ALL, p210‐ALL, and lymphoblastic CML were compared. In spite of significant overlap between the three entities, a number of features were found to aid in their differentiation. p210‐ALL patients present at a younger age with blasts that frequently show loss of expression of CD34, whereas p190‐ALL patients present with marked increase in peripheral blast percentage. Interestingly, bone marrow findings characteristic of a myeloproliferative disorder are specific, but are not sensitive for lymphoblastic CML. This study suggests that despite the similarities between these leukemias, p190‐ALL, p210‐ALL, and lymphoblastic phase CML likely represent three distinct diseases. Am. J. Hematol., 2008. © 2008 Wiley‐Liss, Inc.
Survival and disability in a cohort of neural tube defect births in Dublin, Ireland
Authors: Sutton Marie , Daly Leslie E. , Kirke Peadar N. 
Published: September 2008

AbstractBACKGROUND:Neural tube defects (NTDs) are a major cause of death and disability. Periconceptional folic acid prevents up to 70% of these malformations but public health campaigns to increase use of supplements have had disappointing results: The proposed mandatory fortification of bread products in Ireland has raised concerns about possible side effects. We examined data collected on a cohort of children born with NTDs in an era before fortification/supplementation to illustrate the serious consequences in terms of survival and disability.METHODS:All 623 infants born with NTDs in the Dublin area between 1976 and 1987 were included. Information was collected on mortality and length of survival for those who died, and for those who survived at least 5 years, interview‐based data were collected on age, place of residence, prevalence of hydrocephalus, degree of disability, schooling, and IQ.RESULTS:Seventy‐four births (12%) were stillborn. Of the livebirths only 41% were alive at 5 years. Factors associated with mortality were type of lesion, level of lesion, presence of other defects, hydrocephalus, year of birth, and gestation. Of the children who survived to 5 years or more, 75% had a disability and 56% were severely disabled. Type of lesion and level of lesion influenced disability risk.Of the survivors, 51% of children had mobility limitations, 59% were incontinent, 42% had hydrocephalus, and 17% had intellectual disability.CONCLUSIONS:These findings illustrate the devastating consequences of NTDs and underline the importance of effective intervention programs with folic acid for prevention. Birth Defects Research (Part A) 2008. © 2008 Wiley‐Liss, Inc.
Selective antibody precipitation using polyelectrolytes: A novel approach to the purification of monoclonal antibodies
Authors: McDonald Paul , Victa Corazon , Carter‐Franklin Jayme N. , Fahrner Robert 
Published: September 2008

AbstractWe evaluated the potential for polyelectrolyte induced precipitation of antibodies to replace traditional chromatography purification. We investigated the impact of solution pH, solution ionic strength and polyelectrolyte molecular weight on the degree of precipitation using the anionic polyelectrolytes polyvinylsulfonic acid (PVS), polyacrylic acid (PAA), and polystyrenesulfonic acid (PSS). As we approached the pI of the antibody, charge neutralization of the antibody reduced the antibody–polyelectrolyte interaction, reducing antibody precipitation. At a given pH, increasing solution ionic strength prevented the ionic interaction between the polyelectrolyte and the antibody, reducing antibody precipitation. With increasing pH of precipitation, there was an increase in impurity clearance. Increasing polyelectrolyte molecular weight allowed the precipitation to be performed under conditions of higher ionic strength. PVS was selected as the preferred polyelectrolyte based on step yield following resolubilization, purification performance, as well as the nature of the precipitate. We evaluated PVS precipitation as a replacement for the initial capture step, as well as an intermediate polishing step in the purification of a humanized monoclonal antibody. PVS precipitation separated the antibody from host cell impurities such as host cell proteins (HCP) and DNA, process impurities such as leached protein A, insulin and gentamicin, as well as antibody fragments and aggregates. PVS was subsequently removed from antibody pools to <1 µg/mg using anion exchange chromatography. PVS precipitation did not impact the biological activity of the resolubilized antibody. Biotechnol. Bioeng. 2009;102: 1141–1151. © 2008 Wiley Periodicals, Inc.
Non‐invasive self‐referencing electrochemical sensors for quantifying real‐time biofilm analyte flux
Authors: McLamore E.S. , Porterfield D.M. , Banks M.K. 
Published: September 2008

AbstractCurrent techniques for characterizing biofilm physiology lack the signal filtering capability required for quantifying signals associated with real time biologically active transport. Though a great deal was learned from previous investigations, no results have been reported on the characterization of in vivo, real time biofilm flux using non‐invasive (non‐destructive) techniques. This article introduces the self‐referencing technique for applications in biofilm physiology. Self‐referencing is a non‐invasive sensing modality which is capable of sensing changes in biologically active analyte flux as small as 10 fmol cm−2 s−1. Studies directly characterizing flux, as opposed to concentration, have the advantage of quantifying real time changes in biologically active transport which are otherwise lost to background noise. The use of this modality for characterizing biofilm physiology is validated with a reversible enzyme inhibition study. The experiment used self‐referencing potentiometric sensors for quantifying real time ammonium and nitrite flux. Amperometric and optical sensing methods, though not presented herein, are also powerful sensing tools which benefit from operation in self‐referencing mode. Reversible ammonia monooxygenase inhibition by a copper chelator (thiourea), and subsequent relief by excess copper addition was successfully demonstrated using self‐referencing ion‐selective microelectrodes for a mature Nitrosomonas europaea biofilm. Biotechnol. Bioeng. 2009; 102: 791–799. © 2008 Wiley Periodicals, Inc.