bluuebunny/crossref_metadata_2025 huggingface dataset:
Introduction of a Phe377del Mutation in ANK Creates a Mouse Model for Craniometaphyseal Dysplasia
Authors: Chen I-Ping , Wang Chiachien J , Strecker Sara , Koczon-Jaremko Boguslawa , Boskey Adele , Reichenberger Ernst J
Published: March 2009

Craniometaphyseal dysplasia (CMD) is a monogenic human disorder characterized by thickening of craniofacial bones and flaring metaphyses of long bones. Mutations for autosomal dominant CMD have been identified in the progressive ankylosis gene ANKH. Previous studies of Ank loss-of-function models, Anknull/null and Ankank/ank mice, suggest that Ank plays a role in the regulation of bone mineralization. However, the mechanism for Ank mutations leading to CMD remains unknown. We generated the first knockin (KI) mouse model for CMD expressing a human mutation (Phe377 deletion) in ANK. Homozygous Ank knockin mice (AnkKI/KI) replicate many typical features of human CMD including hyperostosis of craniofacial bones, massive jawbones, decreased diameters of cranial foramina, obliteration of nasal sinuses, fusion of middle ear bones, and club-shaped femurs. In addition, AnkKI/KI mice have increased serum alkaline phosphatase and TRACP5b, as reported in CMD patients. Biochemical markers of bone formation and bone resorption, N-terminal propeptide of type I procollagen and type I collagen cross-linked C-terminal telopeptide, are significantly increased in AnkKI/KI mice, suggesting increased bone turnover. Interestingly, AnkKI/KI bone marrow–derived macrophage cultures show decreased osteoclastogenesis. Despite the hyperostotic phenotype, bone matrix in AnkKI/KI mice is hypomineralized and less mature, indicating that biomechanical properties of bones may be compromised by the Ank mutation. We believe this new mouse model will facilitate studies of skeletal abnormalities in CMD at cellular and molecular levels.
Activin A Enhances Prostate Cancer Cell Migration Through Activation of Androgen Receptor and Is Overexpressed in Metastatic Prostate Cancer
Authors: Kang Hong-Yo , Huang Hsuan-Ying , Hsieh Chang-Yi , Li Chien-Feng , Shyr Chih-Rong , Tsai Meng-Yin , Chang Chawnshang , Chuang Yao-Chi , Huang Ko-En
Published: March 2009

Bone metastasis is the major cause of mortality associated with prostate cancer. Whereas activin A is known to inhibit prostate cancer cell growth and promote apoptosis, the correlation of elevated activin A with increasing serum prostate-specific antigen (PSA) levels in bone metastatic stages of prostate cancer is well documented. The molecular mechanisms explaining these paradoxical effects of activin A and how activin A influences the progression of prostate cancer with bone metastasis remain unclear. By comparing expression profiles of primary prostate cancer biopsies, with and without bone metastasis, we discovered that the expression of activin A is increased in cases with bone metastatic propensity and correlates with increased androgen receptor (AR), PSA expression, and Gleason scores. Activin A promotes migration of prostate cancer cells to osteoblasts, elevates the AR gene transcription through Smads through binding to AR promoter, and induces nuclear translocation of AR to interact with Smad3. Knockdown of Smad3 by siRNA decreases activin A–promoted AR expression and cancer cell migration. Overexpression of AR reversed Smad3-siRNA suppression on activin A–mediated cell migration to osteoblasts. These data suggest that activation of the AR through Smads is required for activin A–promoted prostate cancer cell migration to bone matrix, thereby promoting the bone metastatic phenotype, and the activin A–Smad–AR axis may be considered a therapeutic target in bone metastatic diseases.
Moderate Ingestion of Alcohol Is Associated With Acute Ethanol-Induced Suppression of Circulating CTX in a PTH-Independent Fashion
Authors: Sripanyakorn Supannee , Jugdaohsingh Ravin , Mander Adrian , Davidson Sarah L , Thompson Richard PH , Powell Jonathan J
Published: March 2009

The “J shape” curve linking the risk of poor bone health to alcohol intake is now well recognized from epidemiological studies. Ethanol and nonethanol components of alcoholic beverages could influence bone remodeling. However, in the absence of a solid underlying mechanism, the positive association between moderate alcoholic intake and BMD remains questionable because of confounding associated social factors. The objective of this work was to characterize the short-term effects of moderate alcohol consumption on circulating bone markers, especially those involved in bone resorption. Two sequential blood-sampling studies were undertaken in fasted healthy volunteers (age, 20–47 yr) over a 6-h period using beer of different alcohol levels (<0.05–4.6%), solutions of ethanol or orthosilicic acid (two major components of beer), and water ± calcium chloride (positive and negative controls, respectively). Study 1 (24 subjects) assessed the effects of the different solutions, whereas study 2 (26 subjects) focused on ethanol/beer dose. Using all data in a “mixed effect model,” we identified the contributions of the individual components of beer, namely ethanol, energy, low-dose calcium, and high-dose orthosilicic acid, on acute bone resorption. Markers of bone formation were unchanged throughout the study for all solutions investigated. In contrast, the bone resorption marker, serum carboxy terminal telopeptide of type I collagen (CTX), was significantly reduced after ingestion of a 0.6 liters of ethanol solution (>2% ethanol; p ≤ 0.01, RM-ANOVA), 0.6 liters of beer (<0.05–4.6% ethanol; p < 0.02), or a solution of calcium (180 mg calcium; p < 0.001), but only after calcium ingestion was the reduction in CTX preceded by a significant fall in serum PTH (p < 0.001). Orthosilicic acid had no acute effect. Similar reductions in CTX, from baseline, were measured in urine after ingestion of the test solutions; however, the biological variability in urine CTX was greater compared with serum CTX. Modeling indicated that the major, acute suppressive effects of moderate beer ingestion (0.6 liters) on CTX were caused by energy intake in the early phase (∼0–3 h) and a “nonenergy” ethanol component in the later phase (∼3 to >6 h). The early effect on bone resorption is well described after the intake of energy, mediated by glucagon-like peptide-2, but the late effect of moderate alcohol ingestion is novel, seems to be ethanol specific, and is mediated in a non–calcitonin- and a non–PTH-dependent fashion, thus providing a mechanism for the positive association between moderate alcohol ingestion and BMD.
Genetic Hypercalciuric Stone-Forming Rats Have a Primary Decrease in BMD and Strength
Authors: Grynpas Marc , Waldman Stephen , Holmyard Douglas , Bushinsky David A
Published: March 2009

Kidney stone patients often have a decrease in BMD. It is unclear if reduced BMD is caused by a primary disorder of bone or dietary factors. To study the independent effects of hypercalciuria on bone, we used genetic hypercalciuric stone-forming (GHS) rats. GHS and control (Ctl) rats were fed a low Ca (0.02% Ca, LCD) or a high Ca (1.2% Ca, HCD) diet for 6 wk in metabolic cages. All comparisons are to Ctl rats. Urine Ca was greater in the GHS rats on both diets. GHS fed HCD had reduced cortical (humerus) and trabecular (L1–L5 vertebrae) BMD, whereas GHS rats fed LCD had a reduction in BMD similar to Ctl. GHS rats fed HCD had a decrease in trabecular volume and thickness, whereas LCD led to a ∼20-fold increase in both osteoid surface and volume. GHS rats fed HCD had no change in vertebral strength (failure stress), ductibility (failure strain), stiffness (modulus), or toughness, whereas in the humerus, there was reduced ductibility and toughness and an increase in modulus, indicating that the defect in mechanical properties is mainly manifested in cortical, rather than trabecular, bone. GHS rat cortical bone is more mineralized than trabecular bone and LCD led to a decrease in the mineralization profile. Thus, the GHS rats, fed an ample Ca diet, have reduced BMD with reduced trabecular volume, mineralized volume, and thickness, and their bones are more brittle and fracture prone, indicating that GHS rats have an intrinsic disorder of bone that is not secondary to diet.
Contribution of the Vertebral Posterior Elements in Anterior–Posterior DXA Spine Scans in Young Subjects
Authors: Lee David C , Campbell Patricia P , Gilsanz Vicente , Wren Tishya AL
Published: March 2009

Because DXA is a projection technique, anterior–posterior (AP) measurements of the spine include the posterior elements and the vertebral body. This may be a disadvantage because the posterior elements likely contribute little to vertebral fracture resistance. This study used QCT to quantify the impact of the posterior elements in DXA AP spine measures. We examined 574 subjects (294 females and 280 males), age 6–25 yr, with DXA and QCT. QCT measures were calculated for the cancellous bone region and for the vertebral body including and excluding the posterior elements. DXA data were analyzed for the entire L3 vertebra and for a 10-mm slice corresponding to the QCT scan region. BMC and BMD were determined and compared using Pearson's correlation. The posterior elements accounted for 51.4 ± 4.2% of the total BMC, with a significant difference between males (49.9 ± 4.0%) and females (52.8 ± 3.9%, p < 0.001). This percentage increased with age in younger subjects of both sexes (p < 0.001) but was relatively consistent after age 17 for males and 16 for females (p > 0.10). DXA areal BMD and QCT volumetric BMD correlated strongly for the whole vertebra including the posterior elements (R = 0.83), with BMC measures showing a stronger relationship (R = 0.93). Relationships were weaker when excluding the posterior elements. We conclude that DXA BMC provides a measure of bone that is most consistent with QCT and that the contribution of the posterior elements is consistent in young subjects after sexual maturity.
Serum IGF-1 Determines Skeletal Strength by Regulating Subperiosteal Expansion and Trait Interactions
Authors: Yakar Shoshana , Canalis Ernesto , Sun Hui , Mejia Wilson , Kawashima Yuki , Nasser Philip , Courtland Hayden-William , Williams Valerie , Bouxsein Mary , Rosen Clifford , Jepsen Karl J
Published: March 2009

Strong correlations between serum IGF-1 levels and fracture risk indicate that IGF-1 plays a critical role in regulating bone strength. However, the mechanism by which serum IGF-1 regulates bone structure and fracture resistance remains obscure and cannot be determined using conventional approaches. Previous analysis of adult liver-specific IGF-1–deficient (LID) mice, which exhibit 75% reductions in serum IGF-1 levels, showed reductions in periosteal circumference, femoral cross-sectional area, cortical thickness, and total volumetric BMD. Understanding the developmental sequences and the resultant anatomical changes that led to this adult phenotype is the key for understanding the complex relationship between serum IGF-1 levels and fracture risk. Here, we identified a unique developmental pattern of morphological and compositional traits that contribute to bone strength. We show that reduced bone strength associated with low levels of IGF-1 in serum (LID mice) result in impaired subperiosteal expansion combined with impaired endosteal apposition and lack of compensatory changes in mineralization throughout growth and aging. We show that serum IGF-1 affects cellular activity differently depending on the cortical surface. Last, we show that chronic reductions in serum IGF-1 indirectly affect bone strength through its effect on the marrow myeloid progenitor cell population. We conclude that serum IGF-1 not only regulates bone size, shape, and composition during ontogeny, but it plays a more fundamental role—that of regulating an individual's ability to adapt its bone structure to mechanical loads during growth and development.
BMP Signaling and Podocyte Markers are Decreased in Human Diabetic Nephropathy in Association with CTGF Overexpression
Authors: Turk Tamara , Leeuwis Jan Willem , Gray Julia , Torti Suzy V. , Lyons Karen M. , Nguyen Tri Q. , Goldschmeding Roel
Published: March 2009

Diabetic nephropathy is characterized by decreased expression of bone morphogenetic protein-7 (BMP-7) and decreased podocyte number and differentiation. Extracellular antagonists such as connective tissue growth factor (CTGF; CCN-2) and sclerostin domain-containing-1 (SOSTDC1; USAG-1) are important determinants of BMP signaling activity in glomeruli. We studied BMP signaling activity in glomeruli from diabetic patients and non-diabetic individuals and from control and diabetic CTGF+/+ and CTGF+/− mice. BMP signaling activity was visualized by phosphorylated Smad1, −5, and −8 (pSmad1/5/8) immunostaining, and related to expression of CTGF, SOSTDC1, and the podocyte differentiation markers WT1, synaptopodin, and nephrin. In control and diabetic glomeruli, pSmad1/5/8 was mainly localized in podocytes, but both number of positive cells and staining intensity were decreased in diabetes. Nephrin and synaptopodin were decreased in diabetic glomeruli. Decrease of pSmad 1/5/8 was only partially explained by decrease in podocyte number. SOSTDC1 and CTGF were expressed exclusively in podocytes. In diabetic glomeruli, SOSTDC1 decreased in parallel with podocyte number, whereas CTGF was strongly increased. In diabetic CTGF+/− mice, pSmad1/5/8 was preserved, compared with diabetic CTGF+/+ mice. In conclusion, in human diabetic nephropathy, BMP signaling activity is diminished, together with reduction of podocyte markers. This might relate to concomitant overexpression of CTGF but not SOSTDC1. (J Histochem Cytochem 57:623–631, 2009)
Expertise Differences in Attentional Strategies Related to Pilot Decision Making
Authors: Schriver Angela T. , Morrow Daniel G. , Wickens Christopher D. , Talleur Donald A.
Published: March 2009

Objective: We investigated expertise differences in pilot decision making by examining a hypothesized attention-action link. During simulated flight we measured the accuracy and latency of more and less expert pilots' decision outcomes and used eye tracking to measure their attention. We also examined whether decision outcomes and attentional strategies were influenced by properties of the cues indicating problems. Background: Errors in decision making contribute to many accidents and incidents, especially among inexperienced pilots. Although much is known about decision errors in terms of their outcomes, less is known about the cognitive processes that underlie expert differences in aviation decision making. Method: Fourteen more expert and 14 less expert pilots flew 16 flights in a simulator. Half of the flights contained a failure requiring diagnosis and action in response to the failure. Cues signaling the failures varied in how diagnostic and/or correlated they were. Results: The more expert pilots generally made better decisions in terms of speed and accuracy. Both groups made faster correct decisions when cues were high versus low in diagnosticity. Only the more expert pilots made faster correct decisions when cues were correlated. More attention was allocated to relevant cues (measured by percentage dwell time on areas of interest) when a failure was present, primarily among expert pilots. Moreover, the amount of attention to cues was associated with decision accuracy. Conclusion: The findings support the link between greater attention and more effective decision making. Application: The expert advantage in attention underlying decision outcomes may provide targets for improving pilot training.
Effects of Simulator Practice and Real-World Experience on Cell-Phone—Related Driver Distraction
Authors: Cooper Joel M. , Strayer David L.
Published: March 2009

Objective: Our research examined the effects of practice on cell-phone—related driver distraction. Background: The driving literature is ambiguous as to whether practice can reduce driver distraction from concurrent cell phone conversation. Methods: Drivers reporting either high or low real-world cell phone usage were selected to participate in four 90-min simulated driving sessions on successive days. The research consisted of two phases: a practice phase and a novel transfer phase. Results: Dual-task performance deficits persisted through practice and transfer driving conditions. Moreover, groups reporting high and low real-world experience exhibited similar driving impairments when conversing on a hands-free cell phone. Conclusions: These data indicate that practice is unlikely to eliminate the disruptive effects of concurrent cell phone use on driving. Application: Multiple regulatory agencies have considered, or are currently considering, legislation to restrict in-vehicle cell phone use. Findings reported herein may be useful to inform these public policy decisions.
Age-Related Differences in Reliance Behavior Attributable to Costs Within a Human-Decision Aid System
Authors: Ezer Neta , Fisk Arthur D. , Rogers Wendy A.
Published: March 2009

Objective: An empirical investigation was done to determine if there are age-related differences attributable to costs in reliance on a decision aid. Background: Costs of reliance on a decision aid may affect reliance on the aid. Older and younger adults may not perceive and respond to a dynamic cost structure equally or objectively. Method: Sixteen older adults (65—74 years) and 16 younger adults (18—28 years) performed a counting task with an imperfect decision aid. Two types of costs were manipulated: (a) cost of error (CoE) and (b) cost of verification (CoV). The percentage of trials in which participants agreed with the decision aid and did not perform the task manually was recorded as reliance. Results: Participants decreased their reliance as the CoE increased and increased their reliance with a lower CoV; however, they tended to under-rely on the decision aid. Younger adults tended to change their reliance behavior more than older adults did with the changing cost structure. Conclusions: Older and younger adults appear to interpret costs differently, with older adults being less responsive to changes in costs. Older adults may have been less able to monitor the changing costs and hence not adapt to them as well as younger adults. Application: Designers of decision aids should consider explicitly stating costs associated with reliance on the aid, as individuals may differ in how they interpret and respond to changing costs.
Substrate Durability Guidelines Used in Silicone Structural Attachment
Authors: Carbary Lawrence D.
Published: March 2009

This paper sets forth a procedure for evaluating substrates for durability for use in conjunction with structural silicone glazing (SSG). Lap shear and peel adhesion specimens are evaluated after exposures to various conditions using a modified ASTM C794-06, “Standard Test Method for Adhesion-In-Peel of Elastomeric Joint Sealants,” and ASTM C961-06, “Standard Test Method for Lap Shear Strength of Sealants.” Conditions of exposure include water, sodium hypochlorite (bleach), acetic acid (vinegar), salt fog, UV florescent accelerated weathering device (UVFl), ultraviolet light (UV) exposure, and heat. Evaluation of substrates and the interfaces are completed after tensile testing and visual surface analysis. The silicone structural glazing adhesive used in this evaluation is a high modulus high strength material intended to place the maximum load at the interface. Substrates evaluated include steel, anodized aluminum, galvanized steel, extruded rigid polyvinyl chloride (PVC), glass reinforced thermoplastic resin (fiberglass), and polyvinylidene fluoride (PVDF) painted aluminum. These evaluated substrates are tested to this procedure to show differences in performance and suggest a minimum time frame required for testing. The results and guidelines set forth in this paper provide the foundation for a practice and or a substrate specification for use in conjunction with structural silicone attachment methods.
Methods for Human Demographic Inference Using Haplotype Patterns From Genomewide Single-Nucleotide Polymorphism Data
Authors: Lohmueller Kirk E , Bustamante Carlos D , Clark Andrew G
Published: March 2009

We propose a novel approximate-likelihood method to fit demographic models to human genomewide single-nucleotide polymorphism (SNP) data. We divide the genome into windows of constant genetic map width and then tabulate the number of distinct haplotypes and the frequency of the most common haplotype for each window. We summarize the data by the genomewide joint distribution of these two statistics—termed the HCN statistic. Coalescent simulations are used to generate the expected HCN statistic for different demographic parameters. The HCN statistic provides additional information for disentangling complex demography beyond statistics based on single-SNP frequencies. Application of our method to simulated data shows it can reliably infer parameters from growth and bottleneck models, even in the presence of recombination hotspots when properly modeled. We also examined how practical problems with genomewide data sets, such as errors in the genetic map, haplotype phase uncertainty, and SNP ascertainment bias, affect our method. Several modifications of our method served to make it robust to these problems. We have applied our method to data collected by Perlegen Sciences and find evidence for a severe population size reduction in northwestern Europe starting 32,500–47,500 years ago.
The Genetic Basis of Phenotypic Adaptation I: Fixation of Beneficial Mutations in the Moving Optimum Model
Authors: Kopp Michael , Hermisson Joachim
Published: March 2009

We study the genetic basis of adaptation in a moving optimum model, in which the optimal value for a quantitative trait increases over time at a constant rate. We first analyze a one-locus two-allele model with recurrent mutation, for which we derive accurate analytical approximations for (i) the time at which a previously deleterious allele becomes beneficial, (ii) the waiting time for a successful new mutation, and (iii) the time the mutant allele needs to reach fixation. On the basis of these results, we show that the shortest total time to fixation is for alleles with intermediate phenotypic effect. We derive an approximation for this “optimal” effect, and we show that it depends in a simple way on a composite parameter, which integrates the ecological parameters and the genetic architecture of the trait. In a second step, we use stochastic computer simulations of a multilocus model to study the order in which mutant alleles with different effects go to fixation. In agreement with the one-locus results, alleles with intermediate effect tend to become fixed earlier than those with either small or large effects. However, the effect size of the fastest mutations differs from the one predicted in the one-locus model. We show how these differences can be explained by two specific effects of multilocus genetics. Finally, we discuss our results in the light of three relevant timescales acting in the system—the environmental, mutation, and fixation timescales—which define three parameter regimes leading to qualitative differences in the adaptive substitution pattern.
Characterization of a Novel Thermosensitive Restorer of Fertility for Cytoplasmic Male Sterility in Maize
Authors: Gabay-Laughnan Susan , Kuzmin Evgeny V , Monroe Jessica , Roark Leah , Newton Kathleen J
Published: March 2009

S-type cytoplasmic male sterility (CMS-S) in maize is associated with high levels of a 1.6-kb RNA in mitochondria. This RNA contains two chimeric open reading frames (ORFs), orf355 and orf77. The previously described nuclear restorer-of-fertility allele Rf3 causes the processing of all transcripts that contain these chimeric ORFs. The Lancaster Surecrop-derived inbred line A619 carries a restorer that is distinct from Rf3 in that it selectively reduces only the CMS-S-specific 1.6-kb RNA. We have found that 10 additional Lancaster lines carry a single restoring allele traceable to either of two inbred lines, C103 and Oh40B. The C103 and Oh40B restorers are allelic to each other, but not to Rf3. Thus, this restoring allele, designated Rf9, represents a second naturally occurring CMS-S restorer in maize. Rf9 is a less effective restorer of fertility than is Rf3; its expression is influenced by both inbred nuclear background and temperature. Rf9 acts to reduce the amounts of orf355/orf77-containing linear mitochondrial subgenomes, which are generated by recombination of circular subgenomes with CMS-S-specific linear plasmids. The 1.6-kb RNA, which is transcribed only from linear ends, is correspondingly reduced.
Excision ofHelitronTransposons in Maize
Authors: Li Yubin , Dooner Hugo K
Published: March 2009

Helitrons are novel transposons discovered by bioinformatic analysis of eukaryotic genome sequences. They are believed to move by rolling circle (RC) replication because their predicted transposases are homologous to those of bacterial RC transposons. We report here evidence of somatic Helitron excision in maize, an unexpected finding suggesting that Helitrons can exhibit an excisive mode of transposition.
Institution of Basal-Bolus Therapy at Diagnosis for Children With Type 1 Diabetes Mellitus
Authors: Adhikari Soumya , Adams-Huet Beverley , Wang Yu-Chi A. , Marks James F. , White Perrin C.
Published: March 2009

OBJECTIVE. We studied whether the institution of basal-bolus therapy immediately after diagnosis improved glycemic control in the first year after diagnosis for children with newly diagnosed type 1 diabetes mellitus.

METHODS. We reviewed the charts of 459 children ≥6 years of age who were diagnosed as having type 1 diabetes between July 1, 2002, and June 30, 2006 (212 treated with basal-bolus therapy and 247 treated with a more-conventional neutral protamine Hagedorn regimen). We abstracted data obtained at diagnosis and at quarterly clinic visits and compared groups by using repeated-measures, mixed-linear model analysis. We also reviewed the records of 198 children with preexisting type 1 diabetes mellitus of >1-year duration who changed from the neutral protamine Hagedorn regimen to a basal-bolus regimen during the review period.

RESULTS. Glargine-treated subjects with newly diagnosed diabetes had lower hemoglobin A1c levels at 3, 6, 9, and 12 months after diagnosis than did neutral protamine Hagedorn-treated subjects (average hemoglobin A1c levels of 7.05% with glargine and 7.63% with neutral protamine Hagedorn, estimated across months 3, 6, 9, and 12, according to repeated-measures models adjusted for age at diagnosis and baseline hemoglobin A1c levels; treatment difference: 0.58%). Children with long-standing diabetes had no clinically important changes in their hemoglobin A1c levels in the first year after changing regimens.

CONCLUSION. The institution of basal-bolus therapy with insulin glargine at the time of diagnosis of type 1 diabetes was associated with improved glycemic control, in comparison with more-conventional neutral protamine Hagedorn regimens, during the first year after diagnosis.
The Use of Fractional-Flow Theory for Foam Displacement in Presence of Oil
Authors: Mayberry D. J. , Afsharpoor A. , Kam S. I.
Published: March 2009

Foam has been extensively used in improved and enhanced oil recovery processes in the petroleum industry over decades. Foam is capable of reducing gas mobility dramatically in porous media, and thus helps keep displacement fronts stable by controlling the mobility ratio between injected gas and reservoir fluids. In this study, models were constructed to investigate the mechanisms of foam displacement in porous media using three-phase fractional-flow theory and ternary diagrams. The strength of foam in the presence of oil was accounted for by using a mobility reduction factor (MRF) for the gas phase that can be routinely measured in laboratory coreflood experiments. The use of MRF is a typical way of describing foam rheology in local steady-state modeling.

Results were analyzed in terms of saturation paths in the ternary diagrams, saturation velocities, sweep efficiency and effluent history. Two different initial conditions were selected to demonstrate the importance of initial saturation on the displacement: one with oil phase dominant ((Sw, So) = (0.2, 0.8)) and the other with water phase dominant ((Sw, So) = (0.8, 0.2)). At low MRF (i.e., no foam or weak foam), the efficiency of foam displacement was primarily governed by fast-moving spreading waves that rapidly broke through the porous medium resulting in poor sweep efficiency. An increase in MRF (i.e., stronger foam) altered the nature of the displacement front by making it more piston-like through the development of "shock" fronts and improved sweep efficiency significantly. Once shock fronts dominated the displacement, the importance of initial saturation on the mechanisms of displacement became less pronounced. Calculations also demonstrated that a decrease in oil viscosity made the oil phase more mobile and the formation of shock fronts more prolific, significantly enhancing sweep efficiency.

The results in this study imply that if basic fluid properties, injection and initial saturation conditions, and MRF are known, one can reliably predict the mechanisms of foam displacement in porous media even in the presence of oil. The solutions obtained from the three-phase fractional-flow analysis were in good agreement with simulation results in a wide range of MRF values and initial core conditions.
Fracture-Face-Skin Evolution During Cleanup
Authors: Gdanski Rick , Fulton Dwight , Shen Chun
Published: March 2009

There remains considerable debate about the impact of fracture-face-matrix damage on cleanup and productivity of gas wells. The impact of the Cinco-Ley fracture-face-skin factor has been studied extensively, normally with single-phase-flow examples. Two-phase-flow examples are usually limited to the impact on long-term production. This paper uses a new two-phase-flow simulator to demonstrate the impact of fracture-face-matrix damage on both fracture-treatment cleanup and fracture-face-skin evolution during cleanup and subsequent production. The simulator was validated by comparison of calculated skins with pressure-buildup simulations evaluated by use of a high-end, third-party, pressure-transient-analysis package.

The study has demonstrated that fracture-face skin relative to gas flow can be calculated continually throughout a simulation of fracture-treatment cleanup and production. It was found that at lower matrix permeabilities and subsequent higher capillary pressure curves, the impact of water saturation in the damage zone becomes much more important. Specifically, the effective fracture-face skin relative to gas can be several times higher than expected on the basis of single-phase flow. Furthermore, the simulation results show that at lower matrix permeabilities, the time required to achieve a reasonable fracture-face skin relative to gas flow can require considerable production time, on the order of several weeks, even for moderate damage factors. The results demonstrate that in tight gas reservoirs (≈0.01 md and less), even a moderate amount of matrix damage in a fracture face can result in high fracture-face skins and exceedingly long times for treatment cleanup. As such, it becomes very important to minimize fracture-face-matrix damage during tight gas fracturing treatments.
Identifying the Potential Upside of Hydrocarbon Saturation From Electric Logs
Authors: Worthington Paul F.
Published: March 2009

Validated electrical type curves, which collectively describe a continuum of conductivity behavior of fluid-saturated rocks, allow the petrophysical evaluation of hydrocarbon saturation to be set within a generic reference framework. As part of this process, the type curves permit pre-existing data from other reservoirs to be examined as potential analogs. Through the type curves, a reservoir rock can be classified in terms of its electrical character, specifically adherence to, or departures from, classical clean-sand (Archie) conditions and, by corollary, the degree of any shale (non-Archie) effects. The classification guides the approach to future core-data acquisition and to well-log analysis. In particular, in non-Archie reservoirs the type curves indicate whether the formation-water salinity is sufficiently high for the application of shaly-sand equations for the evaluation of hydrocarbon saturation or whether recourse should be made to a (customized) pseudo-Archie approach. Thus, the type curves are used to ensure that interpretative algorithms are appropriate to the petrophysical task at hand.

The application of the type curves, using initializing log data from seven shaly hydrocarbon reservoirs containing relatively fresh formation waters, has illustrated how petrophysical interpretations away from the key intervals can be screened with minimal supporting information through a pseudo-Archie approach. Comparisons of best estimates of hydrocarbon-filled porosity with previously reported values have indicated a potential volumetric upside in all cases, with hydrocarbon saturations being up to 30 saturation units higher for these complex reservoirs. This outcome is attributed to the generic nature of the screening process, which takes account of the electrical character of a reservoir without any of the procedural constraints that are associated with conventional well-log analysis. To reduce further the risk of underestimating hydrocarbon volumes, a set of equivalence charts has been constructed using basic petro-physical properties. The equivalence charts allow a quick-look recognition of any departures from Archie conditions and thence whether the type curves are likely to be required.

The screening process has been synthesized into pragmatic workflows, whose adoption should impart additional quality assurance to the petrophysical evaluation of hydrocarbon volumes.
Efficient Field-Scale Simulation of Black Oil in a Naturally Fractured Reservoir Through Discrete Fracture Networks and Homogenized Media
Authors: Li Liyong , Lee Seong H.
Published: March 2009

This paper describes a hybrid finite volume method, designed to simulate multiphase flow in a field-scale naturally fractured reservoir. Lee et al. (WRR 37:443-455, 2001) developed a hierarchical approach in which the permeability contribution from short fractures is derived in an analytical expression that from medium fractures is numerically solved using a boundary element method. The long fractures are modeled explicitly as major fluid conduits. Reservoirs with well-developed natural fractures include many complex fracture networks that cannot be easily modeled by simple long fracture formulation and/or homogenized single continuity model. We thus propose a numerically efficient hybrid method in which small and medium fractures are modeled by effective permeability, and large fractures are modeled by discrete fracture networks. A simple, systematic way is devised to calculate transport parameters between fracture networks and discretized, homogenized media. An efficient numerical algorithm is also devised to solve the dual system of fracture network and finite volume grid. Black oil formulation is implemented in the simulator to demonstrate practical applications of this hybrid finite volume method.
A Novel Stimulation Technique for Horizontal Openhole Wells in Carbonate Reservoirs—A Case Study in Kuwait
Authors: Liu Hai , Coston Chad , Yassin Mohamed , Uddin Shahab , Dhafeeri Fahad Al
Published: March 2009

Effective matrix acidizing in Kuwait's horizontal openhole wells is a big challenge. Reservoir heterogeneity and the length of the horizontal wells make acid placement and diversion difficult, particularly in high-water-cut (WC) wells in which water has broken through as a result of high-permeability streaks or natural fractures. Furthermore, acid penetration is limited by the large surface area of the horizontal wellbore, and this is exacerbated by the relatively small injection rate imposed by the use of coiled tubing (CT). To make matters worse, formation damage in horizontal wells is usually very deep as a result of long exposure times.

This paper discusses the application of a new viscoelastic-surfactant (VES)-based, self-diverting acid system for stimulation of more than 20 horizontal openhole wells in carbonate reservoirs in Kuwait. The application also deployed a new nonparticulate material that forms a highly viscous plug when it contacts water and that degrades when mixed with oil in the formation. The new fluid system is pumped before the acid treatment to effectively prevent the acid from stimulating high-water-saturation sections.

The field results show significant improvement in post-stimulation production, owing to effective diversion and water-production control compared with wells in which a conventional polymer-diversion technique was used in the past with no consideration for water-production control in high-WC cases. The new technique has been selected as the standard stimulation practice in most horizontal openhole carbonate wells in Kuwait.
Application of Diluted Consolidation Systems To Improve Effectiveness of Proppant Flowback Remediation—Laboratory and Field Results
Authors: Nguyen Philip D. , Weaver Jimmie D. , Rickman Richard D. , Sanders Michael W.
Published: March 2009

Individually, coiled tubing (CT), consolidating fluids, or pressure-pulsing tools do not represent new technology. However, the combination of these technologies offers a viable solution to the proppant flowback problem after the proppant has been placed in the fracture. This paper presents the results of laboratory studies and field case histories of a remedial treatment technique through use of a low-viscosity consolidation fluid system that is placed into the propped fractures by CT or jointed pipe coupled with a pressure-pulsing tool. The treatment fluids are designed to provide consolidation (for previously placed proppant) near the wellbore to glue the proppant grains in place without damaging the permeability of the proppant pack.

Laboratory flow testing indicates that the proppant pack in a fracture model under closure stress only requires low-strength bonds between proppant grains to withstand high production flow rates. The consolidation treatment transforms the loosely packed proppant in the fractures and the formation sand close to the well-bore into a cohesive, consolidated, yet highly permeable pack. Field case histories are presented and the treatment procedures, precautions and recommendations for implementing the treatment process are discussed. One major advantage of this remedial treatment method is the ability to place the treatment fluid into the propped fractures, regardless of the number of perforation intervals and the length of the perforated intervals without mechanical isolation between the intervals. The fluid-placement efficiency of this process makes remediation economically feasible, especially in wells with marginal reserves.
Hydraulic-Fracture-Model Sensitivity Analyses of a Massively Stacked, Lenticular, Tight Gas Reservoir
Authors: Green Christopher A. , Barree Robert D. , Miskimins Jennifer L.
Published: March 2009

This paper assesses critically the importance of various inputs that are used for a common method to develop a simulator model of hydraulic fractures (HFs) in geologically complex, fluvial, tight gas reservoirs. A planar 3D fracture simulator is used with a fully coupled fluid-/solids-transport simulator. The geomechanical rock properties from logs (Young's modulus, Poisson's ratio, and Biot's constant) and diagnostic minifracture injection tests of individual sandstone reservoirs were investigated to assess their importance in developing a valid stress model.

This paper describes the investigations by use of a model matched previously with both net surface pressure and microseismic/tiltmeter data. From these results, it is possible to obtain a better understanding of how fractures grow and interact with complex fluvial reservoirs, allowing operators to optimize field-well performance and completion methods better in these geologic settings. Additionally, the minimum critical data recommendations necessary to develop such a model have been identified and will aid operators in developing their data-acquisition programs. Although developed in the Rocky Mountain region, the presented technique can be extended to other similar geologically complex reservoirs worldwide.
Analysis and Comparison of Decline Models: A Field Case Study for the Intercampo Oil Field, Venezuela
Authors: Dou Hong'en , Chen Changchun , Chang Yuwen , Fang Yanjun , Chen Xinbin , Liu Wei , Cai Wenxin
Published: March 2009

Intercampo oil field, which contains unconsolidated reservoirs driven by edge water and bottom water, is characterized by heavy oil with mid-high permeability and high oil saturation. The three classical models of the Arps model were applied in 13 horizontal and vertical wells in the oil field; also, the paper introduces two models that are not widely applied for decline analysis and forecasting in the wells. Decline features between vertical and horizontal wells were compared. The results accord well with the actual data from the oil field. The authors point out that these decline analysis models are applicable not only for vertical wells but also for horizontal wells. The authors would like to emphasize that four decline models discussed in the paper. In regard to screening and comparison of decline analysis models, this paper illustrates how to select and use a model, as well as the model's application conditions and their features. The screened models are recommended for production performance analysis of wells, reservoirs and oil fields.
Bati Raman Field Immiscible CO2 Application—Status Quo and Future Plans
Authors: Sahin Secaeddin , Kalfa Ulker , Celebioglu Demet
Published: March 2009

The Bati Raman field is the largest oil field in Turkey and contains approximately 1.85 billion bbl of oil initially in place. The oil is heavy (12°API), with high viscosity and low solution-gas content. Primary recovery was less than 2% of oil originally in place (OOIP).

Over the period of primary recovery (1961–86), the reservoir underwent extensive pressure depletion from 1,800 psig to as low as 400 psig in some regions, resulting in a production decline from 9,000 to 1,600 STB/D.

In March 1986, a carbon-dioxide (CO2)-injection pilot in a 1,200-acre area containing 33 wells was initiated in the western portion of the field. The gas-injection was initially cyclic. In 1988, the gas injection scheme was converted to a CO2-flood process. Later, the process was extended to cover the whole field.

A peak daily production rate of 13,000 STB/D was achieved, whereas rate would have been less than 1,600 STB/D without CO2 application. However, the field has undergone a progressive production decline since 1995to recent levels of approximately 5,500 STB/D. Polymer-gel treatments were carried out to increase the CO2 sweep efficiency. Multilateral- and horizontal-well technology also was applied on a pilot scale to reach the bypassed oil. A water-alternating-gas (WAG) application has been applied extensively in the western part of the field. Current production is 7,000 STB/D.

This paper documents more than 25 years of experience of the Turkish Petroleum Corporation (TPAO) on the design and operation of this full-field immiscible CO2-injection project conducted in the Bati Raman oil field in Turkey. The objective is to update the current status report, update the reservoir/field problems that TPAO has encountered (unpredictable problems and results), and provide a critical evaluation of the success of the project.
EOR Pilot Tests With Modified Enzyme—Dagang Oilfield, China
Authors: Feng Qing-xian , Ma Xian-ping , Zhou Li-hong , Shao Ding-bo , Wang Xiao-lin , Qin Bao-yan
Published: March 2009

Micro- and macroevaluations were conducted to understand modified-enzyme enhanced-oil-recovery (EOR) mechanisms using various fluids. Huff'n'puff and flooding tests were carried out with variable modified-enzymes concentrations in several reservoirs. The resulting production performances were improved considerably. At reservoir temperature 50 to 80°C, laboratory experiments indicated that the modified enzyme solution was adaptable to both light and heavy oil and was not sensitive to minerals, water with bivalent cation (1000 mg/L), or high salinity (10%). The enzyme working performances were enhanced further with microorganism occurrence in the solution. The micromodeling experiment reveals that spontaneous emulsification and solubilization can take place between the modified enzyme and crude with emulsion particles of 2–6 μm in diameter, which are produced through stripping as a result of solubilization. Core desorption and flooding experiments suggest that desorbed crude volume and displacement efficiency are related to modified-enzyme concentrations that usually ranged from 5 to 10%, with the optimum being 8%. In optimal conditions, recovery can, on average, be increased by 16.9%. Experiments also proved that the modified enzyme and crude oil could form an emulsion, but the emulsion was not stable. One specific pilot test with modified enzyme had achieved additional oil production of 22,869 bbl.
Stimulation of Bypassed Pay Zones in Existing Wellbores
Authors: Moreno J. W. , Engler T. W.
Published: March 2009

A significant portion of the US gas resources is located in low-permeability, bypassed pay zones, within multilayered sandstone-shale sequences. Acquiring these resources leads to operational and design difficulties in stimulation, particularly if the target zone is bounded above and below by existing producing zones. The objective of this work was to evaluate the impact of adjacent, existing producing zones on the stimulation design and therefore production performance of the bypassed payzone.

To investigate this problem, a 3D planar, hydraulic fracture propagation model was constructed and superimposed on a 3D flow model. The physical model comprises three layers, the top and bottom representing previously stimulated and producing layers, and the middle layer the target or bypassed layer. The impact of lithology, fracture length, and total stress variations over time on the fracture conductivity, fracture efficiency, and average reservoir pressure were investigated.

Evidence of pressure depletion of the target layer was observed caused by production of the upper and lower layers. The degree of depletion is dependent on the fracture length and lithology of all of the layers. That is, the ability to propagate a fracture in the target layer was a strong function of the shale content and to a lesser extent, on the hydraulic fracture length of the bounding layers. Increased shale content in the target as well as the bounding layers resulted in a decrease in fracture conductivity of the target layer. However, an increase in fracture length did not necessarily result in a decrease in fracture conductivity of the target layer.

The study includes examples of stimulating the Menefee formation in the San Juan basin.