bluuebunny/crossref_metadata_2025_split huggingface dataset:
Shrinkage of Oil Well Cement Slurries
Authors: Backe K.R. , Skalle P. , Lile O.B. , Lyomov S.K. , Justnes H. , Sveen J. 
Published: March 2010

Abstract
Gas leakage into and through the cemented annulus in oil and gas wells is a safety problem. The conditions for gas migration develop when the hydrostatic pressure of the hydrating cement slurry column slowly declines and finally falls below the pore pressure of a gas bearing formation. This pressure decline is mainly caused by chemical shrinkage of the cement. A low shrinkage will reduce the pressure decline and hence the risk of gas migration.
A new and simple method for measurement of total chemical shrinkage at high temperatures has been developed. It has proved to be reliable and sensitive for monitoring the cement hydration process. The equipment was used to show that there is a marked difference in shrinkage behaviour for the tested slurries up to 180 ° C, probably due to a temperature effect on the cement hydration chemistry. The results confirmed the correlation between total shrinkage and cement content, and thus it follows that using more extender will reduce the likelihood of gas migration.

Introduction
Cement slurries are used in oil and gas wells for cementing the steel casing to the wellbore and thus sealing the rock formations from the well. Gas leakage into and through the cemented annulus is still a problem, in particular where shallow gas sands are penetrated and in deep gas wells, i.e., under high temperature and high pressure (HTHP) conditions. The leakage may manifest itself either as vertical communication between permeable gas reservoirs or migration all the way to the surface. Gas pressure in excess of the cement hydrostatic slurry pressure is the driving force behind gas migration.
Reasons and mechanisms of gas migration are discussed by Levine et al.,(1) Sabins et al.(2), and Cheung and Beirute(3). Annular gas flow may be initiated when the hydrostatic pressure of the cement slurry declines and falls below the pore pressure of a gas bearing formation due to the combined effect of shrinkage, fluid loss to the porous well bore and gel strength build up. Normally a slurry volume reduction would be compensated for by contraction and downward movement of fluids from above, thus maintaining its hydrostatic head. However, during the setting process the cement slurry develops a gel structure causing it to stick to the wall thus hindering compensation of the shrinkage. The second requirement for gas migration is that the cement must enable gas flow into the cement either by permeability, channels, microannuli or microfractures before the slurry has reached a sufficient strength. Thus, the gas migration phenomenon is thought to be initiated during the transition state, from being fluid to becoming hard, i.e., between initial and final set of the cement.
A low shrinkage is preferable because the resulting hydrostatic pressure decline will be lower than for a slurry with high shrinkage, i.e., pressure equilibrium between gas and slurry column is reached at a later point of time.
The chemical shrinkage may be divided into two parts: external shrinkage and total shrinkage.
WCB-The Little Oil Patch That Could
Authors: Knoll R.G. 
Published: March 2010

Introduction
In terms of crude oil production, Canada is a relatively minor league player, ranking 14th among producing countries with 2.5% of the world total-Table 1(1). If considering the two largest producing provinces in the WCB (Western Canadian Basin) alone, Alberta would rank approximately 21st with less than 1.3% of the world's total. Saskatchewan produces roughly half that of Alberta, and would be on a par with Yemen (30th). Yet the WCB industry holds a globally dominant position in the key innovative exploitation technology (horizontal wells) and plays a major role in the related technical pursuits (UBD-Underbalanced Drilling, ERD- Extended Reach Drilling, coiled-tubing and multi-branch technology).

Domination by Numbers
In terms of scale of application of horizontal wells, the WCB is the world leader. Saskatchewan alone has in excess of 3,300 horizontal wells. Alberta, with over twice the resource base of Saskatchewan, has a 5,300+ horizontal well population. Collectively, the WCB claims a total approaching 10,000 wells, 40 - 60% of the world total(2). The world share can only be approximated since horizontal well statistics are not readily available from many of the major producing regions.
Why is it that a region producing less than 2.5% of the world's crude would have a dominant position in the application of this advanced exploitation method? Outside observers might assume that the basin is characterized by one major reservoir type which is particularly conducive to horizontal well applications (e.g., the Austin Chalk of Texas). They may perceive that the application was championed by a large operator applying the technology to relatively huge fields (e.g., Statoil in Norway, or ADNOC in the UAE). On the contrary, the WCB is extremely diverse.
Figure 1 provides a sample cross-section of horizontal wells drilled in the WCB in the period 1989 to 1993, the formative years of this technology in Canada. The TVD (true vertical depth) of these reservoirs varies from tens of metres to a number of kilometres. There is almost every conceivable type of hydrocarbon production (bitumen to deep sour gas), in many varied structures and lithologies. All the production processes are employed from primary through to the most advanced EOR (Enhanced Oil Recovery) methods, such as steam assisted gravity drainage (SAGD).
In comparison to the world's major producing areas, the WCB would be described as a region of relatively thin, varied, depleted reservoirs of limited reserves and meagre profit margins. In Saskatchewan for example, pay zones frequently have net pay of less than five metres. Yet, in this marginal setting, oil production has increased over 90% in the last decade in large part due to the exponential growth of horizontal well applications(3). It is valid to state that, in general, the thinner the reservoir, the more attractive a horizontal well vs. a vertical well. However, it is simplified to suggest that a world technical dominance is solely resultant of a minor producing region having small, thin, depleted reserves in a very marginal profit setting.
Rock/Bit Imbalance Force Prediction
Authors: Ziaja M.B. 
Published: March 2010

Abstract
It is important to be able to predict the instantaneous forces and moments at the bit during drilling, but the rock/bit interaction process is not thoroughly understood. It is commonly accepted that the forces acting on a drag bit should be balanced to avoid excessive bit vibrations called whirling and uncontrolled well deviation resulting from non-symmetric side cutting. However, the relationships between drilling forces and bit design features are uncertain because of the difficulty in obtaining reliable, quantitative measurements of cutting forces at the bit.
A series of single cutter PDC (Polycrystalline Diamond Compact) experiments were conducted in the laboratory; in which three components of drilling force were measured. A rock was cut at the speed and load corresponding to the same parameters while PDC bit drilling. The variations in the value and direction of the resultant force were compared with the variations of the depth of cut and the simulated wellbore pressure. The relationship between the cross-section of cut rock and the measured forces at a PDC cutter were analysed and used in the rock/bit modelling. A model for the resultant force at the bit was developed by integrating the effects of individual PDC cutters into geometry of a given PDC bit design. The model describing kinematics of the PDC bit, as well as the imbalance force resulting from the non-symmetric distribution of drilling forces was developed. Then, simulations of the rocklbit interaction forces were run for the different depth of cut and a given rock described by the index of rock strength and coefficient of friction between the rock and PDC cutter. The predictions obtained of imbalance force and moments at the bit are presented for the conventional and bi-centre PDC bit designs. The results clearly indicate the differences between these two designs, as well as the ability to predict the magnitude and orientation of the imbalance force generated while drilling with different PDC bit designs in different rock lithologies.

Introduction
The unexpected and excessive PDC cutter wear, as well as the problems related to uncontrolled and/or unintended well deviations were recognized in the late 1980s. In 1989, a new theory of PDC bit failure was presented and called "bit whirl." It has been recognized that the bit stability is influenced mainly by lateral force causing a bit to walk around the wellbore. Since that time, research has focussed almost entirely on modelling the whirling motion of the centre of the bit and modelling the low static imbalance force at the bit. Some improvements have been obtained by developing techniques that stabilize the bit and generate the restoring force necessary to prevent the start of whirl. However, the mechanism of rock cutting is still not well enough understood to accurately predict the distribution of forces and moments at the bi-centre PDC bit and the resulting bit behaviour on instantaneous time scale while drilling. The main reasons are the following: 1) the directional tendencies of PDC bits have not been clearly defined to this point.
Solubility of CO, NO, CH, And CH In Polar Solvents
Authors: Henni A. , Mather A.E. 
Published: March 2010

Abstract
The solubility of carbon dioxide, nitrous oxide, methane and ethane in a physical solvent, triethylene glycol monomethyl ether (TEGMME) was recently measured by Henni and Mather(1–4) at 40, 70, and 100 ° C at pressures up to 10.9 MPa. TEGMME was found to be the best solvent for CO2 removal among the physical solvents used in the gas processing industry. In order to compare these solubility data with those of other polar solvents, a literature search was done to gather solubility data in solvents with a wide range of dielectric constants. The solubility data compiled were for pressures higher than atmospheric pressure and the Peng-Robinson(5) equation of state was used to correlate the data for the solubility of CO2 in these polar solvents. The Henry's Law constants are then derived using the Kritchevsky-Kasarnovsk(6) or the Kritchevsky-Iliinskaya(7) equation. The results show that ethyl acetate and propyl acetate are the two solvents that have the highest capacity for CO2 absorption. Among the solvents that absorb CO2 the most, TEGMME has the highest boiling point; this translates into lower solvent losses in the regeneration section. Dimethyl ether is among the best solvents for CO2 absorption but it is also among solvents that absorbs methane the most. Diethyl ether comes at the top of the list in its ability to absorb.
The study confirms the fact that the best physical solvents for absorbing acid gases have the disadvantage of absorbing the largest amounts of ethane. It also recommends the use of this new solvent TEGMME as a new solvent for acid gas removal.
The solubility data in the CO2, N2O, CH4 and C2H6 systems were generally well-correlated by the Peng-Robinson equation of state even for those systems that are highly non-ideal.

Introduction
The Government of Canada has been an active participant in the development of international agreements and protocols for emissions reduction. It has committed the country to meeting national emission caps for anthropogenic air emissions. Just how these national targets will be met is a critical question to provincial governments but also to oil, coal and utility companies in Canada. Since carbon dioxide is a major contributor to the global warming phenomenon, the process of carbon dioxide removal from coal-fired power plants and its utilisation as a flooding agent for enhanced oil recovery (EOR) is the focus of considerable of attention. The CO2 captured will generate revenues and will help reduce emissions that contribute to the greenhouse effect.
Zawacki et al.(8) have screened more than 100 solvents for their potential of removing acidic gases (CO2, H2S). The dimethyl ether of tetraethylene glycol (DMETEG) was chosen as one of two most promising solvents. In an attempt to provide the industry with better physical solvents, a study was initiated to test new physical solvents.
Triethylene glycol monomethyl ether [TEGMME, C.A. Registry No. 112-35-6] was chosen in the initial study as it belongs to the same chemical family as DMETEG but it costs four times less.
Serving Two Masters: The Association between Audit Committee Internal Audit Oversight and Internal Audit Activities
Authors: Abbott Lawrence J. , Parker Susan , Peters Gary F. 
Published: March 2010

SYNOPSIS: In this paper, we investigate the association between the audit committee’s oversight of the internal audit function (IAF) and the nature of IAF activities. The importance of internal controls and of the roles of both the audit committee and the internal audit function in monitoring control activities have grown in recent years. Despite the importance of these topics, relatively little regulatory or best practices guidance addresses the distribution of IAF activities and amount of audit committee involvement with the IAF. We hypothesize that when the balance of oversight over the IAF lies with the audit committee (vis-a`-vis management), the committee will steer the IAF toward a more internal-controls-oriented focus. Our hypothesis is based on the existing practice guidance in this area and the relative incentives of management and the audit committee.
To test our hypothesis, we survey 134 chief internal auditors from Fortune 1000 firms regarding the amount of internal audit resources allocated across internal audit activities in fiscal year 2005. We then construct a composite measure of audit committee oversight contingent on the relative control that the audit committee has over IAF vis-a`-vis management. Our composite measure is derived from three key facets of the audit committee/internal audit relationship: reporting duties, termination rights, and budgetary control. Consistent with our hypothesis, we document a strong, positive association between our audit committee oversight variable and the amount of IAF budget allocated to internal-controls-based activities.
Non‐cigarette tobacco use among women and adverse pregnancy outcomes
Authors: ENGLAND LUCINDA J. , KIM SHIN Y. , TOMAR SCOTT L , RAY CECILY S , GUPTA PRAKASH C. , EISSENBERG THOMAS , CNATTINGIUS SVEN , BERNERT JOHN T. , TITA ALAN THEVENET N. , WINN DEBORAH M. , DJORDJEVIC MIRJANA V. , LAMBE MATS , STAMILIO DAVID , CHIPATO TSUNGAI , TOLOSA JORGE E. 
Published: March 2010

AbstractAlthough cigarette smoking remains the most prevalent form of tobacco use in girls and in women of reproductive age globally, use of non‐cigarette forms of tobacco is prevalent or gaining in popularity in many parts of the world, especially in low‐ and middle‐income countries. Sparse but growing evidence suggests that the use of some non‐cigarette tobacco products during pregnancy increases the risk of adverse pregnancy outcomes. In this paper we review the literature on the prevalence of non‐cigarette tobacco product use in pregnant women and in women of reproductive age in high‐, middle‐, and low‐income countries and the evidence that maternal use of these products during pregnancy has adverse health effects. In addition, we communicate findings from an international group of perinatal and tobacco experts that was convened to establish research priorities concerning the use of non‐cigarette tobacco products during pregnancy. The working group concluded that attempts to develop a public health response to non‐cigarette tobacco use in women are hindered by a lack of data on the epidemiology of use in many parts of the world and by our limited understanding of the type and magnitude of the health effects of these products. We highlight research gaps and provide recommendations for a global research agenda.
Advice given by health‐care professionals to mothers concerning subsequent pregnancy after stillbirth
Authors: RÅDESTAD INGELA , HUTTI MARIANNE , SÄFLUND KARIN , ONELÖV ERIK , WREDLING REGINA 
Published: March 2010

AbstractWe studied the advice mothers with stillbirths were given concerning a suitable time to become pregnant. A questionnaire was sent in 2001 to mothers with a stillbirth at one of five hospitals in the Stockholm region in Sweden. At three months follow‐up, 33 mothers participated and at 12 months 31. The advices varied from waiting one to 12 months. Eleven mothers were advised to trust their own feelings of readiness and six were advised to wait until they had dealt with their grief before becoming pregnant. At one year post‐loss, most of the mothers felt that a suitable time for a subsequent pregnancy was as soon as the mother herself wanted. Mothers whose baby had died in utero were given radically different kinds of advice concerning a suitable time for a subsequent pregnancy. The best advice seems to be that the mother should wait until she, herself, feels ready.
Darunavir/ritonavir and efavirenz exert differential effects on MRP1 transporter expression and function in healthy volunteers
Authors: Lee Lawrence S , Soon Gaik H , Shen Ping , Yong Eu-Leong , Flexner Charles , Pham Paul 
Published: March 2010

Background The efflux transporter MRP1 actively transports antiretrovirals and reduces intracellular accumulation in peripheral blood mononuclear cells (PBMCs). We studied MRP1 expression and function in healthy volunteers treated with darunavir/ritonavir and efavirenz. Methods Seven healthy HIV-negative volunteers were recruited. PBMCs were collected at baseline, 9 days after administration of darunavir (900 mg) and ritonavir (100 mg) once daily, 9 days after coadministration of darunavir/ritonavir and efavirenz (600 mg) once daily and 13 days after administration of efavirenz alone. MRP1 expression was measured in PBMCs using flow cytometry with fluorescein isothiocyanate-conjugated antibody against MRP1m6. MRP1 expression was also measured in CD4+ T-cells with a phycoerythrin-conjugated antibody against CD4. MRP1 efflux function was assessed by incubating PBMCs with carboxyfluorescein diacetate (CFDA) and comparing CFDA fluorescence with and without the modulators MK571 and probenecid. Results MRP1 expression was reduced after darunavir/ ritonavir administration (geometric mean ratio [GMR] 0.58, 95% confidence interval [95% CI] 0.51–0.65; P<0.001) and darunavir/ritonavir plus efavirenz coad-ministration (GMR 0.74, 95% CI 0.64–0.84; P=0.001), but not after efavirenz administration alone (GMR 0.82, 95% CI 0.64–1.06; P=0.10). MRP1 protein expression was 41% higher in CD4+ T-cells. MRP1 efflux function was increased after efavirenz administration (GMR 3.13, 95% CI 2.73–3.59; P<0.001) and darunavir/ritonavir plus efavirenz coadministration (GMR 4.35, 95% CI 3.35–5.68; P<0.001), but not after darunavir/ritonavir administration (GMR 1.06,§ 95% CI 0.80–1.42; P=0.42). Conclusions Darunavir/ritonavir and efavirenz treatment exerted differential effects on MRP1 expression and function. These effects could potentially alter antiviral activity, especially in CD4+ T-cells.
Minimally Important Difference for Patient-reported Outcomes in Psoriatic Arthritis: Health Assessment Questionnaire and Pain, Fatigue, and Global Visual Analog Scales
Authors: KWOK TIFFANY , POPE JANET E. 
Published: March 2010

Objective.To determine the minimally important difference (MID) for the Health Assessment Questionnaire-Disability Index (HAQ-DI), pain, fatigue, sleep, and global visual analog scale (VAS; 0–100 mm) in patients with psoriatic arthritis (PsA) using a patient-reported overall health status anchor. Patient-reported outcomes are often used to gauge the effect of PsA in clinical trials. There is currently no knowledge about the MID for patient-reported outcomes in PsA.Methods.Patients with a diagnosis of PsA who had answered questions about outcomes at 2 consecutive visits and an overall health status question (“How would you describe your overall status since your last visit: much better, better, the same, worse, much worse?”) were included. MID was calculated as the mean change between visits for those who rated their disease as “better” or “worse.”Results.Two hundred patients met inclusion criteria, of whom 17.5% rated their status as “better” and 25.0% rated their status as “worse” than the previous visit. MID estimates for improvement/worsening (SD) respectively were −0.131 (0.411)/0.131 (0.309) for HAQ-DI, −9.37 (24.37)/13.96 (22.05) for pain VAS, −8.15 (23.52)/3.63 (27.62) for fatigue VAS, −10.97 (29.74)/13.81 (27.32) for sleep VAS, and −8.41 (21.17)/11.53 (21.03) for global VAS. Spearman’s r correlation coefficients between the anchor and mean change were 0.374 (HAQ-DI), 0.448 (pain VAS), 0.239 (fatigue VAS), 0.326 (sleep VAS), 0.490 (global VAS); p < 0.01.Conclusion.This is the first study investigating MID of patient-reported outcomes in PsA. MID for HAQ-DI, pain, and global VAS were shown to be the best predictors for a patient’s perception of overall changes in disease status.
Continuing Education Needs of Nurses in a Voluntary Continuing Nursing Education State
Authors: Nalle Maureen A. , Wyatt Tami H. , Myers Carole R. 
Published: March 2010

Background:
Understanding the personal and professional motivations that shape learning needs is fundamental to high-quality continuing nursing education (CNE). This statewide survey assessed nurses’ CNE needs, learning priorities, perceived benefits and barriers, and motivation for voluntary CNE participation.

Methods:
An online needs assessment accessed through state professional organizations’ websites and various health care facilities was available to all registered nurses in the state. The needs assessment included demographic and professional characteristics and items related to CNE preferences and barriers.

Results:
Among 672 nurses, motivating factors for CNE participation varied and priority learning needs included leadership and management, evidence-based practice, and advanced practice issues. CNE program costs, travel, and time away from work were key barriers to participation.

Conclusion:
CNE participation is influenced by personal, professional, and organizational factors. In the absence of state mandates, policy changes are needed to promote CNE and overcome persistent barriers to participation.