bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wellhead Managers Improve Operating Efficiencies In the Pembina Field-A Case Study
Authors: Reynolds M. , Sutton J. , Hedberg G. 
Published: March 2010

Abstract
The Pembina field is the largest oilfield in Canada with in excess of 5,000 current operating wells. The field has been on production for more than 40 years and under waterflood since the early 1960s. In spite of its advanced productive life, this field contains a large amount of remaining reserves. Reducing or controlling operating costs today and into the future will be a major challenge due to the advanced age of the wells and facilities.
One of the technologies used to control operating costs in aging fields has been wellhead managers with and without remote control (SCADA). Petro-Canada investigated wellhead automation in a number of mature fields in Canada and the U.S. prior to the implementation of a ten well test project in the Pembina field. There were a number of objectives to be studied during the pilot test:Reduce the number of bottom hole equipment failures related to fluid poundReduce the amount of lost production related to equipment failures with better surveillanceProve the applicability in low oil rate, high water cut wells in a mature waterfloodOptimize the use and reduce the cost of paraffin and scale control chemicalsDemonstrate the effectiveness of using an integrated team of production engineering, field technical and operations staff during the design and implementation phases of the test.
Wellhead managers had proven successful in reducing costs and production losses in other fields, therefore the pilot test was expected to last for a maximum of six months. The main purpose of the test was to gain the field operators' support of the system, as well as quantify the benefits under Pembina operating conditions prior to a field wide expansion of a fully automated SCADA system.

Introduction
The Pembina Cardium Field(1) located in west central Alberta is the largest oilfield in Canada in terms of both areal extent and original oil in place. The portions of the field operated by Petro- Canada are located in the southeastern area near the village of Buck Creek (Figure 1). The first producing wells were drilled in this area in 1954 with first waterflooding started in 1957. By 1961, all Petro-Canada operated areas were under waterflood.
This area was operated by Norcen Energy and predecessor companies up until 1994 when Petro-Canada was elected operator. The Cardium reservoir in this area has responded well to waterflooding and the production trend is characterized as low decline (4 to 7% per year) with a long remaining reserves life index in spite of more than 40 years of past production. The operated properties consist of approximately 120 producing wells, 100 injection wells and 20 suspended wells. Most of the area is on 80 acre well spacing and 160 acre five spot waterflood patterns. There are six separate tank batteries complete with water plants and numerous satellite testing facilities scattered throughout the property.
Barite Segregation In Inclined Boreholes
Authors: Skalle P. , Backe K.R. , Lyomov S.K. , Sveen J. 
Published: March 2010

Abstract
Settling and sagging of barite in inclined boreholes may lead to safety and operational problems. To study the effect of rheology on settling, a laboratory tool was designed, consisting of two connected tubes, one inclined and one vertical. The hydrostatic pressure was measured at the bottom of each pipe. Stable and unstable muds can clearly be differentiated through their pressure behaviour.
Several muds were studied at simulated static and dynamic conditions. The results show that sagging is most severe during laminar flow and also indicate that the rheological parameters may be used for predicting stability problems.

Introduction
In weighted drilling mud barite tends to segregate slowly. In directional drilling operations the settling process is accelerated. Barite settles in the lower side of the borehole and starts sliding when the borehole has an inclination above 30 °. This phenomenon is known as barite sagging. Sagging can lead to drilling and completion problems; a density variation or non-linear hydrostatic pressure gradients which can lead to pressure control problems, while thick and tight barite beds can lead to high torque and drag, stuck pipes and plugged boreholes, and even lost circulation.
The sag problem is related to the so called Boycott effect(1), first described in 1920. Hanson et al.(2) have investigated the phenomenon and found that most of the sagging occurs while the mud is circulating. The same conclusion was reached by Bern et al.,(3) the sagging tendency is highest at low annular velocities. Zamora and Jefferson(4) presented a method for tracking drilling fluid density variations, which helps to detect, but not to predict drilling mud instability. Jamison and Clements(5) developed a test method to characterise settling and sag tendencies in static drilling fluids, however their equipment was not able to distinguish between settling and sliding. They also found that their data, based upon standard API rheological parameters like PV and YP, were unsuitable for prediction of sagging behaviour. It is apparent from previous works that the most difficult part of the problem is the prediction of drilling mud instabilities for both static and flowing drilling fluids. To date there are no API test procedures for sag testing.
A new simple laboratory tool was therefore designed for the purpose to study and develop a method to predict sagging.

Drilling Mud Separation

Settling of Particles
In vertical wells the settling of weighting material is generally not a problem due to the long settling distance. In horizontal wells the distance to the lower side of the wall is only about 0.2 m, which leads to rapid generation of solids beds. The settling velocity of a single spherical particle, vs,l, in a fluid is expressed by Stoke's law(6):
Equation 1 (available in full paper)
A barite particle (ρp = 4,200 kg/m3) with a diameter (dp) of 20 µm in a fluid of density (ρfluid) 1,500 kg/m3 and a viscosity (µ??of 40 cP will settle at a rate of 53 mm/h.
A Practical Well Control Methodology While Drilling Without Returns
Authors: Schneider G. , Osisanya S.O. 
Published: March 2010

Abstract
While drilling in some oil fields of the world, lost circulation may be so severe that normal remedies that might heal the loss zone are not effective. A procedure has been developed to drill "blind" or without returns. The procedure has been refined enough so that stuck drill pipe may be avoided, but the most dangerous aspect of drilling "blind" is the lack of well control. Often when circulation is lost, the well kicks and gas can flow into the wellbore due to drastic reduction in hydrostatic pressure. Furthermore, normal well control operations are ineffective. The procedure generally involves pumping a viscous slug of waterbased gel mud into the annulus and this column of mud is called a "mudcap." This approach depends on whether the lost zone is above or below a gas zone and either approach effectively limits the amount of fluid that can be used.
In order to properly place a mudcap, a better understanding of the relationship between the fluid rheological properties, column height, and the initial shut-in casing pressure is required. In this respect, no quick field procedure has been developed to help rigsite personnel to control these types of wells. A set of charts have been constructed to aid field personnel in blowout prevention, when they are confronted with a gas kick occurring while drilling without returns. This situation is common in many oil fields especially in Middle East and North Africa. The set of charts is based on the slot flow approximation for Bingham fluids. Two sets of charts are developed: one for the case in which pipe is in the hole and the other when the casing is opened.
Each of the charts represents a different annular configuration. These charts make life easier for rig personnel especially in a very stressful situation, and this type of pre-planning should help to avoid costly mistakes in judgment.

Introduction
Solutions for equations describing axial annular flow of Newtonian fluids can be determined directly. However, direct methods for solving annular flow equations for more complex rheological models, such as Bingham-Plastic and Power-Law, usually result in unwieldy expressions. To avoid this the slot flow approximation was developed. This method equates the geometry of an annulus to that of a narrow slot. Depending upon the geometric parameters used in the narrow slot approximation and the degree of accuracy required, some sort of correction for the curvature of annulus may be needed.
Therefore, a suitable expression for the Newtonian curvature correction factor must be developed. Using the same correction factor as for Newtonian fluids, a slot flow approximation of the axial annular flow of Bingham-Plastic fluids should be relatively accurate. The primary purpose of this paper was to develop relations that describe the annular flow of Bingham-Plastic fluids and the pressure gradient necessary to initiate flow. With an expression that relates pressure gradient to the Bingham Plastic yield point, a set of practical charts was developed.
Observations and Design Considerations for In Situ Combustion Projects
Authors: Moore R.G. , Laureshen C.J. , Mehta S.A. , Ursenbach M.G. 
Published: March 2010

Abstract
An important part of any engineer's tool box is a set of simple equations thatwill allow one to quickly assess the performance potential of a given project. For many years, the model of Nelson and McNeil, as well as that of Gates and Ramey, have remained the standards for the preliminary design of in situcombustion projects. However, advances have been made in our understanding ofthe fundamental mechanisms and reaction kinetics of the combustion process, both for heavy and light oils. Combining established procedures with animproved interpretation of the mechanisms forms the basis for this paper. Theinclusion of the negative temperature gradient region, which affects thetransition to the high-temperature combustion mode, is one of the key elementsof these advances.
The paper also addresses the sizing of air injection capacity and itsimportance, as well as the monitoring and analysis of gas-phase combustionproducts. In summary, the paper will provide the engineer with some realisticguidelines for estimating the oil recovery performance of an in situ combustionproject.

Background
In situ combustion is an enhanced recovery process with tremendous theoreticalpotential, but it has failed to perform up to expectations in many of its fieldimplementations. Two decades of research work at the University of Calgary onin situ combustion has focussed on the question "What makes in situ combustionfail?" While many mechanisms have been identified, the most critical withregard to heavy oil is the temperature of the oxidation (combustion)reactions.
Figures 1 and 2 illustrate the importance of the oxidation zone temperature onthe residual oil and oil production for Athabasca bitumen (8 ° API). Figure 1shows high residual hydrocarbon concentrations for temperatures of less than300 ° C, while Figure 2 shows that no tests exhibited significant levels of oilrecovery for reaction temperatures of less than 350 ° C. These data, which werepreviously reported by Moore et al.(1), were determined by heatingpre-mixed Athabasca Oil Sands cores in a one dimensional core holder at a rateof 40 ° C/hr. while flowing an oxygen containing gas. Maximum oil recoveriesfor these ramped temperature oxidation tests were significantly lower thanthose for combustion tube tests due to the oxidation of the oil during theperiod of heating when temperatures were less than 300 ° C. However, thequalitative behaviour was similar in both types of tests.
What these ramped temperature oxidation data show is that the mobilizationefficiency of air is low for oxidation temperatures of less than 300 ° C. However, reaction temperatures in excess of 350 ° C, while necessary, are not asufficient condition to mobilize oil from the region swept by the oxidationzone. It was found that elevated levels of oil recovery were associated with arapid transition of the leading edge temperatures to a value in excess of 350 °C.
Derivative Analysis Without Type Curves
Authors: Mattar L. 
Published: March 2010

Abstract
Modern type curve analysis involves matching the pressures and their semilog derivative on a set of dimensionless type curves, and selecting a match point. Using this point and a specified matching curve, reservoir parameters such as permeability, skin, fracture half length, fracture conductivity, etc., can be calculated.
This paper shows that the same parameters can be obtained without having to use the type curves. In fact, only the semilog derivative of the data is needed on log-log coordinates. The various flow regimes such as wellbore storage, radial, linear, bilinear or spherical flow can be identified by their characteristic slopes (1, 0, 0.5, 0.25, -0.5). By simply placing a straight line with the appropriate slope on the (semilog) derivative points, all the required reservoir parameters can be calculated. This technique is, in actual fact, a combination in one single plot, of all the specialized analyses (which are traditionally done on their own individual scales, semilog, square-root, quad-root, cartesian).
In addition to the semilog derivative data, it is advisable to superimpose a plot of PPD (Primary Pressure Derivative). This enables the analyst to differentiate between reservoir and wellbore effects, and thereby avoid some of the common pitfalls when using real (as opposed to synthetic) data.

Introduction
"Type Curve" analysis has been used in the field of hydrology since the mid 1930s. In the 1970s, type curves(2,3) were introduced to the petroleum industry, and in the early 1980s Bourdet et al.(1) added the "derivative," which helped in making type curve matching more unique.
This article will explain how analysis of well test data can be achieved by using log-log plots and derivative, but without the need for "type curves." In order to understand this new procedure, a review of how type curve analysis works, will first be presented, and then extended to illustrate the new methods.

Type Curve Matching: (The old way)
The theory underlying type curve matching is fully explained in the ERCB (now AEUB) Gas Well Testing manual(2) and Earlougher(3). Basically the process consists of matching field data onto pre-selected dimensionless "type curves," and from the match point, calculating permeability, skin, wellbore storage constant, reservoir size, etc. Once a satisfactory match of the field data and the type curves has been obtained, a "match point" is chosen (any arbitrary point will do), and its coordinates read simultaneously from both the "type curve" scale and the "data" scale. From the coordinates of this arbitrary point, reservoir or wellbore characteristics can be calculated. For example to obtain permeability, read the vertical values ΔpD and Δp of the dimensionless type curve and of the data plot, at the selected common match point. From the definition of dimensionless pressure, the calculation of permeability is easily obtained as follows:
Equation (available in full paper)
In a similar manner, other variables can be calculated, once a match has been obtained.
Traditional type curve analysis has two major drawbacks:
Case-control study to evaluate risk factors for the development of sepsis (neutropenia and fever) in dogs receiving chemotherapy
Authors: Sorenmo Karin U. , Harwood Lisa P. , King Lesley G. , Drobatz Kenneth J. 
Published: March 2010

Abstract
Objective—To identify risk factors for development of sepsis in dogs treated with chemotherapeutics and to evaluate the impact of sepsis on outcome.
Design—Case-control study.
Animals—Client-owned dogs with various cancers undergoing standard chemotherapeutic treatment at the University of Pennsylvania veterinary hospital.
Procedures—39 dogs with sepsis (cases) were identified through a search of the medical record database. Controls (n = 77) were randomly selected from dogs admitted during the same time period. Variables analyzed included patient demographics, tumor type, stage, remission status, treatment phase, chemotherapeutics used, and outcome.
Results—Dogs that weighed less and dogs with lymphoma were significantly more likely to become septic, compared with larger dogs or dogs with solid tumors. Septic dogs were also significantly more likely to have received doxorubicin (odds ratio [OR], 12.5; 95% confidence interval [CI], 2.4 to 66.0) or vincristine (OR, 9.0; 95% CI, 1.6 to 52.0) than controls. Of the 39 cases, 28 (71.8%) were in the induction phase of their protocol, and 19 of 39 (48.7%) became septic after receiving the chemotherapeutic drug for the first time. Median survival time of the cases (253 days) was not significantly different from that of the controls (371 days).
Conclusions and Clinical Relevance—Dogs that weighed less were at increased risk for chemotherapy-induced sepsis. Tumor type and chemotherapeutic drug used were also important risk factors. These results may lead to the implementation of prophylactic measures, especially when doxorubicin or vincristine is used in the induction phase in small dogs with lymphoma.
Evaluation of outcomes in dogs treated for pyothorax: 46 cases (1983–2001)
Authors: Boothe Harry W. , Howe Lisa M. , Boothe Dawn M. , Reynolds Loren A. , Carpenter Mark 
Published: March 2010

Abstract
Objective—To determine the effect of treatment approach on outcome and the appropriateness of initial empirical antimicrobial treatment in dogs with pyothorax.
Design—Retrospective case series.
Animals—46 dogs with pyothorax confirmed by either (n = 15) or both (31) of the following: intracellular bacteria in pleural fluid or tissue (41) and bacteria recovered via culture of pleural fluid (36).
Procedures—Medical records of dogs treated for pyothorax from 1983 through 2001 were reviewed. Data on signalment, history, clinical signs, and treatment and results of diagnostic imaging and cytologic and microbiological evaluations were obtained. Follow-up was performed via reexamination (n = 15) and contact with referring veterinarians (26) and owners (24).
Results—46 dogs were treated with at least 1 antimicrobial and thoracocentesis (n = 7; noninvasive group), a thoracostomy tube (26; invasive group) with or without pleural lavage and heparin, or a thoracotomy (13; surgical group) and thoracostomy tube with or without pleural lavage and heparin. Pyothorax recurred in 7 dogs, and 5 of the 7 died or were euthanatized. In the respective groups, the short-term survival rate was 29%, 77%, and 92% and the long-term survival rate was 29%, 71%, and 70%. Pleural lavage and heparin treatment increased the likelihood of short- and long-term survival. Results of antimicrobial susceptibility testing suggested empirical antimicrobial selection was associated with a 35% risk of inefficacy.
Conclusions and Clinical Relevance—In the dogs with pyothorax in this study, favorable treatment effects were achieved with surgery (for short-term survival) and pleural lavage and heparin treatment (for short- and long-term survival). Findings failed to support the hypothesis that invasive (surgical) versus noninvasive treatment of pyothorax in dogs leads to a better long-term outcome.
Mycophenolate mofetil treatment in dogs with serologically diagnosed acquired myasthenia gravis: 27 cases (1999–2008)
Authors: Dewey Curtis W. , Cerda-Gonzalez Sofia , Fletcher Daniel J. , Harb-Hauser Marcella F. , Levine Jonathan M. , Badgley Britton L. , Olby Natasha J. , Shelton G. Diane 
Published: March 2010

Abstract
Objective—To compare clinical outcome in dogs with serologically diagnosed acquired myasthenia gravis (MG) treated with pyridostigmine bromide (PYR) with that of dogs treated with mycophenolate mofetil (MMF) and PYR (MMF + PYR).
Design—Retrospective case series.
Animals—27 dogs.
Procedures—Medical records from August 1999 through February 2008 were reviewed to identify dogs with serologically diagnosed acquired MG treated with PYR or MMF + PYR. Data collected for each dog included signalment, whether the dog had megaesophagus or pneumonia (or both), thyroid hormone concentration, remission, time to remission, and survival time. Rates for detection of clinical signs and survival time were compared. Survival time was estimated via the Kaplan-Meier method. Influence of drug treatment protocol on likelihood of remission, time to remission, and survival time was examined. Effects of MMF treatment, megaesophagus, pneumonia, and low serum thyroid hormone concentration on time to remission and survival time were also analyzed.
Results—12 dogs were treated with PYR, and 15 were treated with MMF + PYR. Mortality rates were 33% (PYR) and 40% (MMF + PYR). There was pharmacological remission in 5 and 6 dogs in the PYR and MMF + PYR groups, respectively. No significant differences were detected between treatment groups for remission rate, time to remission, or survival time. Megaesophagus, pneumonia, and low serum thyroid hormone concentration had no significant effect on time to remission or survival time for either treatment group.
Conclusions and Clinical Relevance—The results did not support routine use of MMF for the treatment of dogs with acquired MG.
Tobacco use and secondhand smoke exposure during pregnancy in low‐ and middle‐income countries: the need for social and cultural research
Authors: NICHTER MIMI , GREAVES LORRAINE , BLOCH MICHELE , PAGLIA MICHAEL , SCARINCI ISABEL , TOLOSA JORGE E. , NOVOTNY THOMAS E. 
Published: March 2010

AbstractTobacco use is a leading cause of death and of poor pregnancy outcome in many countries. While tobacco use is decreasing in many high‐income countries, it is increasing in many low‐ and middle‐income countries (LMICs), where by the year 2030, 80% of deaths caused by tobacco use are expected to occur. In many LMICs, few women smoke tobacco, but strong evidence indicates this is changing; increased tobacco smoking by pregnant women will worsen pregnancy outcomes, especially in resource‐poor settings, and threatens to undermine or reverse hard‐won gains in maternal and child health. To date, little research has focused on preventing pregnant women's tobacco use and secondhand smoke (SHS) exposure in LMICs. Research on social and cultural influences on pregnant women's tobacco use will greatly facilitate the design and implementation of effective prevention programs and policies, including the adaptation of successful strategies used in high‐income countries. This paper describes pregnant women's tobacco use and SHS exposure and the social and cultural influences on pregnant women's tobacco exposure; it also presents a research agenda put forward by an international workgroup convened to make recommendations in this area.