bluuebunny/crossref_metadata_2025 huggingface dataset:
Male involvement in birth preparedness and complication readiness for emergency obstetric referrals in rural Uganda
Authors: Kakaire Othman , Kaye Dan K , Osinde Michael O
Published: May 2011

Background

Every pregnant woman faces risk of life-threatening obstetric complications. A birth-preparedness package promotes active preparation and assists in decision-making for healthcare seeking in case of such complications. The aim was to assess factors associated with birth preparedness and complication-readiness as well as the level of male participation in the birth plan among emergency obstetric referrals in rural Uganda.

Methods

This was a cross-sectional study conducted at Kabale regional hospital maternity ward among 140 women admitted as emergency obstetric referrals in antenatal, labor or the postpartum period. Data was collected on socio-demographics and birth preparedness and what roles spouses were involved in during developing the birth plan. Any woman who attended antenatal care at least 4 times, received health education on pregnancy and childbirth danger signs, saved money for emergencies, made a plan of where to deliver from and made preparations for a birth companion, was deemed as having made a birth plan. Multivariate logistic regression analysis was conducted to analyze factors that were independently associated with having a birth plan.

Results

The mean age was 26.8 ± 6.6 years, while mean age of the spouse was 32.8 ± 8.3 years. Over 100 (73.8%) women and 75 (55.2%) of their spouses had no formal education or only primary level of education respectively. On multivariable analysis, Primigravidae compared to multigravidae, OR 1.8 95%CI (1.0-3.0), education level of spouse of secondary or higher versus primary level or none, OR 3.8 95%CI (1.2-11.0), formal occupation versus informal occupation of spouse, OR 1.6 95%CI (1.1-2.5), presence of pregnancy complications OR 1.4 95%CI (1.1-2.0) and the anticipated mode of delivery of caesarean section versus vaginal delivery, OR 1.6 95%CI (1.0-2.4) were associated with having a birth plan.

Conclusion

Individual women, families and communities need to be empowered to contribute positively to making pregnancy safer by making a birth plan.
Differential pathogenicity of two different recombinant PVYNTN isolates in Physalis floridana is likely determined by the coat protein gene
Authors: Hu Xinxi , Nie Xianzhou , He Changzheng , Xiong Xingyao
Published: May 2011

A previous study has identified two types of recombinant variants of Potato virus Y strain NTN (PVYNTN) in China and sequenced the complete genome of the variant PVYNTN-HN2. In this study, the complete genome of isolate PVYNTN-HN1 was fully sequenced and analyzed. The most striking difference between the two variants was the location of recombinant joint three (RJ3). In PVYNTN-HN1, like other typical European-PVYNTN isolates such as PVYNTN-Hun, the RJ3 was located at nucleotide (nt) 9183, namely the 3' proximal end of the CP gene (nt. 8571-9371), thus leading to most (the first 613 nucleotides from the 5' proximal end) of the CP gene (801 bp) with a PVYN origin and PVYN-serotype; whereas in contrast, the RJ3 in PVYNTN-HN2 was located at nt 8572, consequently leading to a CP gene of PVYO origin and PVYO-serotype. The varied genome composition among PVYO, PVYN, PVYN:O, PVYNTN-HN1 and PVYNTN-HN2 made them useful for the investigation of possible roles of gene segment(s) in symptom formation on host plants. When Physalis floridana plants were infected with different PVY isolates, two types of symptoms were induced. PVYN and PVYNTN-HN1 induced mild symptoms (mainly mild mottling) whereas PVYO, PVYN:O and PVYNTN-HN2 induced serve symptoms including leaf and stem necrosis, leaf-drop and stunting. These results, together with a previous study using artificial PVY chimeras, demonstrate that the CP gene, especially the 5' proximal segment (nt 8572-9183), and/or CP likely determine the pathogenicity of PVY in P. floridana.
Effect of Chemokine Receptors CCR7 on Disseminated Behavior of Human T cell Lymphoma: clinical and experimental study
Authors: Yang Jing , Wang Shengyi , Zhao Guofan , Sun Baocun
Published: May 2011

Background

The expression of chemokine receptors CCR7 has been studied in relation to tumor dissemination and poor prognosis in a limited number of cancers. No such studies have been done on CCR7 expression in non-Hodgkin's lymphoma (T-NHL). Our aim in this paper is to investigate the association between CCR7 expression and progression and prognosis of T-NHL.

Methods

1) Analysis of clinical data: The specimens were obtained from 41 patients with T-NHL and 19 patients with lymphoid hyperplasia. Their corresponding clinicopathologic data were also collected. The expression levels of CCR7, MMP-2, and MMP-9 were examined by immunohistochemical staining. 2) Human T-NHL cell lines Hut 78 (cutaneous T-cell lymphoma) and Jurkat (adult T-cell leukemia/lymphoma) were cultured. The invasiveness of the two cell lines were measured with a Transwell invasion assay, and then used to study the effects of chemokine receptors on T-NHL invasion and the underlying molecular mechanism. The transcript and expression of CCR7 were evaluated using RT-PCR and western blotting.

Results

1) The higher CCR7 and MMP-9 expression ratios were significantly associated with multiple lesions and higher stage III/IV. Moreover, a positive correlation was observed between CCR7 and MMP-9 expression. 2) The Hut 78 cell line was more invasive than the Jurkat cells in the Transwell invasion assay. The transcript and expression levels of CCR7 were significantly higher in Hut78 than that of Jurkat cell line. The T-NHL cell lines were co-cultured with chemokine CCL21 which increased the invasiveness of T-NHL cell. The positive association between CCL21 concentration and invasiveness was found. 3) The stronger transcript and expression of PI3K, Akt and p- Akt were also observed in Hut78 than in Jurkat cell line.

Conclusions

High CCR7 expression in T-NHL cells is significantly associated with lymphatic and distant dissemination as well as with tumor cell migration and invasionin vitro. Its underlying mechanism probably involves the PI3K/Akt signal pathway.
Modulation of human β-defensin-1 (hBD-1) in plasmacytoid dendritic cells (PDC), monocytes, and epithelial cells by influenza virus, Herpes simplex virus, and Sendai virus and its possible role in innate immunity
Authors: Ryan Lisa K , Dai Jihong , Yin Zhiwei , Megjugorac Nicholas , Uhlhorn Victoria , Yim Sunghan , Schwartz Kyell D , Abrahams Joshua M , Diamond Gill , Fitzgerald-Bocarsly Patricia
Published: May 2011

hBD comprise a family of antimicrobial peptides that plays a role in bridging the innate and adaptive immune responses to infection. The expression of hBD-2 increases upon stimulation of numerous cell types with LPS and proinflammatory cytokines. In contrast, hBD-1 remains constitutively expressed in most cells in spite of cytokine or LPS stimulation; however, its presence in human PDC suggests it plays a role in viral host defense. To examine this, we characterized the expression of hBD-1 in innate immune cells in response to viral challenge. PDC and monocytes increased production of hBD-1 peptide and mRNA as early as 2 h following infection of purified cells and PBMCs with PR8, HSV-1, and Sendai virus. However, treatment of primary NHBE cells with influenza resulted in a 50% decrease in hBD-1 mRNA levels, as measured by qRT-PCR at 3 h following infection. A similar inhibition occurred with HSV-1 challenge of human gingival epithelial cells. Studies with HSV-1 showed that replication occurred in epithelial cells but not in PDC. Together, these results suggest that hBD-1 may play a role in preventing viral replication in immune cells. To test this, we infected C57BL/6 WT mice and mBD-1(−/−) mice with mouse-adapted HK18 (300 PFU/mouse). mBD-1(−/−) mice lost weight earlier and died sooner than WT mice (P=0.0276), suggesting that BD-1 plays a role in early innate immune responses against influenza in vivo. However, lung virus titers were equal between the two mouse strains. Histopathology showed a greater inflammatory influx in the lungs of mBD-1(−/−) mice at Day 3 postinfection compared with WT C57BL/6 mice. The results suggest that BD-1 protects mice from influenza pathogenesis with a mechanism other than inhibition of viral replication.
Endogenous PMN sialidase activity exposes activation epitope on CD11b/CD18 which enhances its binding interaction with ICAM-1
Authors: Feng Chiguang , Zhang Lei , Almulki Lama , Faez Sepideh , Whitford Melissa , Hafezi-Moghadam Ali , Cross Alan S
Published: May 2011

Diapedesis is a dynamic, highly regulated process by which leukocytes are recruited to inflammatory sites. We reported previously that removal of sialyl residues from PMNs enables these cells to become more adherent to EC monolayers and that sialidase activity within intracellular compartments of resting PMNs translocates to the plasma membrane following activation. We did not identify which surface adhesion molecules were targeted by endogenous sialidase. Upon activation, β2 integrin (CD11b/CD18) on the PMN surface undergoes conformational change, which allows it to bind more tightly to the ICAM-1 and ICAM-2 on the EC surface. Removal of sialyl residues from CD18 and CD11b, by exogenous neuraminidase or mobilization of PMN sialidase, unmasked activation epitopes, as detected by flow cytometry and enhanced binding to ICAM-1. One sialidase isoform, Neu1, colocalized with CD18 on confocal microscopy. Using an autoperfused microflow chamber, desialylation of immobilized ICAM-1 enhanced leukocyte arrest in vivo. Further, treatment with a sialidase inhibitor in vivo reversed endotoxin-induced binding of leukocytes to ICAM-1, thereby suggesting a role for leukocyte sialidase in the cellular arrest. These data suggest that PMN sialidase could be a physiologic source of the enzymatic activity that removes sialyl residues on β2 integrin and ICAM-1, resulting in their enhanced interaction. Thus, PMN sialidase may be an important regulator of the recruitment of these cells to inflamed sites.
Soils contaminated with explosives: Environmental fate and evaluation of state-of-the-art remediation processes (IUPAC Technical Report)
Authors: Kalderis Dimitrios , Juhasz Albert L. , Boopathy Raj , Comfort Steve
Published: May 2011

An explosion occurs when a large amount of energy is suddenly released. This energy may come from an over-pressurized steam boiler, from the products of a chemical reaction involving explosive materials, or from a nuclear reaction that is uncontrolled. In order for an explosion to occur, there must be a local accumulation of energy at the site of the explosion, which is suddenly released. This release of energy can be dissipated as blast waves, propulsion of debris, or by the emission of thermal and ionizing radiation. Modern explosives or energetic materials are nitrogen-containing organic compounds with the potential for self-oxidation to small gaseous molecules (N2, H2O, and CO2). Explosives are classified as primary or secondary based on their susceptibility of initiation. Primary explosives are highly susceptible to initiation and are often used to ignite secondary explosives, such as TNT (2,4,6-trinitrotoluene), RDX (1,3,5-trinitroperhydro-1,3,5-triazine), HMX (1,3,5,7-tetranitro-1,3,5,7-tetrazocane), and tetryl (N-methyl-N-2,4,6-tetranitro-aniline).
Gender-related differences in MEN1 lesion occurrence and diagnosis: a cohort study of 734 cases from the Groupe d'étude des Tumeurs Endocrines
Authors: Goudet P , Bonithon-Kopp C , Murat A , Ruszniewski P , Niccoli P , Ménégaux F , Chabrier G , Borson-Chazot F , Tabarin A , Bouchard P , Cadiot G , Beckers A , Guilhem I , Chabre O , Caron P , Du Boullay H , Verges B , Cardot-Bauters C
Published: May 2011

Context

Multiple endocrine neoplasia type 1 (MEN1) disease is an autosomal dominant syndrome that is believed to equally affect men and women. This assumption has never been confirmed.

Objective

The aims of this study were to evaluate the impact of gender on the prevalence of MEN1 lesions, on their lifetime probability of occurrence, and on the diagnosis of MEN1.

Design

Data regarding a study of 734 cases of MEN1 from the multicenter ‘Groupe d'étude des Tumeurs Endocrines’ were analyzed.

Results

There were 57.8% females. The prevalence and probability of pancreatic tumors were higher in males than in females (P=0.06, P=0.0004). This difference was due to gastrinomas. The prevalence and probability of developing pituitary tumors were significantly greater in females (P<0.001, P<0.0001). Thymic tumors were exclusively found in men. There were no significant gender differences in the prevalence and the probability of developing hyperparathyroidism, or adrenal and bronchial tumors, or in the proportion of positive genetic tests. A family history of MEN1 was more frequently found in men than in women at the time of diagnosis (P=0.02). In the case of pituitary tumor, the proportion of patients diagnosed with MEN1 at the time of the first lesion was lower in women (44.2%) than in men (67.3%).

Conclusion

The phenotype expression of the MEN1 disease gene was different in males and females. In female patients, the possibility of MEN1 is not sufficiently taken into account. Any patient presenting a lesion that belongs to the MEN1 spectrum, such as a pituitary tumor, should be closely questioned about their family history and should be tested for hypercalcemia.
Life-threatening metabolic alkalosis in Pendred syndrome
Authors: Kandasamy Narayanan , Fugazzola Laura , Evans Mark , Chatterjee Krishna , Karet Fiona
Published: May 2011

Introduction

Pendred syndrome, a combination of sensorineural deafness, impaired organification of iodide in the thyroid and goitre, results from biallelic defects in pendrin (encoded by SLC26A4), which transports chloride and iodide in the inner ear and thyroid respectively. Recently, pendrin has also been identified in the kidneys, where it is found in the apical plasma membrane of non-α-type intercalated cells of the cortical collecting duct. Here, it functions as a chloride–bicarbonate exchanger, capable of secreting bicarbonate into the urine. Despite this function, patients with Pendred syndrome have not been reported to develop any significant acid–base disturbances, except a single previous reported case of metabolic alkalosis in the context of Pendred syndrome in a child started on a diuretic.

Case report

We describe a 46-year-old female with sensorineural deafness and hypothyroidism, who presented with severe hypokalaemic metabolic alkalosis during inter-current illnesses on two occasions, and who was found to be homozygous for a loss-of-function mutation (V138F) in SLC26A4. Her acid–base status and electrolytes were unremarkable when she was well.

Conclusion

This case illustrates that, although pendrin is not usually required to maintain acid–base homeostasis under ambient condition, loss of renal bicarbonate excretion by pendrin during a metabolic alkalotic challenge may contribute to life-threatening acid–base disturbances in patients with Pendred syndrome.
Analysis of expression and function of the inhibitory receptor ILT2 in lymphocytes from patients with autoimmune thyroid disease
Authors: Doníz-Padilla Lesly , Paniagua Amalia E , Sandoval-Correa Pilar , Monsiváis-Urenda Adriana , Leskela Susanna , Marazuela Mónica , González-Amaro Roberto
Published: May 2011

Objective

Autoimmune thyroid disease (AITD) is characterized by different defects in immunoregulatory mechanisms. The immunoglobulin-like transcript receptor 2 (ILT2) or leukocyte Ig-like receptor 1 (LIRB1/CD85j) exerts an important immunoregulatory role. We hypothesized that the lymphocytes from AITD patients have a diminished expression and function of ILT2. The aim of this study was to investigate the expression and function of ILT2 in lymphocytes from patients with AITD.

Design and methods

In this study, 18 patients with Hashimoto's thyroiditis (HT), 20 with Graves' disease, and 26 healthy controls were studied. ILT2 expression was analyzed by flow cytometry and immunohistochemistry in peripheral blood mononuclear cells (PBMC) and thyroid tissue. The regulatory function of ILT2 was assessed by an assay of inhibition of lymphocyte proliferation and by an analysis of cell cycle progression. The effect of ILT2 on cytokine synthesis was also evaluated.

Results

We found a significant increased expression of ILT2 by lymphocytes in AITD patients. ILT2 was also detected in the leukocyte infiltrate of thyroid tissue from HT patients. On the contrary, a significant diminished inhibitory activity of ILT2 on cell proliferation was observed in AITD patients. In addition, PBMC from AITD patients showed a diminished synthesis of interleukin 10 on ILT2 engagement.

Conclusions

The abnormal expression and function of ILT2 detected in AITD suggests that this receptor may participate in the pathogenesis of this condition.
Long-term outcome following interstitial laser photocoagulation of benign cold thyroid nodules
Authors: Døssing Helle , Bennedbæk Finn Noe , Hegedüs Laszlo
Published: May 2011

Aim

To evaluate the long-term efficacy of interstitial laser photocoagulation (ILP) in solitary benign thyroid nodules.

Design and methods

A total of 78 euthyroid outpatients (45 participating in randomized trials) with a benign solitary solid and scintigraphically cold thyroid nodule causing local discomfort were assigned to ILP. ILP (using one laser fiber) was performed under continuous ultrasound (US) guidance and with an output power of 1.5–3.5 W. Thyroid nodule volume was assessed by US and thyroid function determined by routine assays, before and during follow-up. Pressure symptoms and cosmetic complaints were evaluated on a visual analogue scale (0–10 cm). Of the total patients, six had thyroid surgery 6 months after ILP and three were lost to follow-up. The median follow-up for the remaining 69 patients was 67 months (range 12–114).

Results

The overall median nodule volume decreased from 8.2 ml (range 2.0–25.9) to 4.1 ml (range 0.6–33.0; P<0.001) at the final evaluation, corresponding to a median reduction of 51% (range: −194 to 95%). This correlated with a significant decrease in pressure as well as cosmetic complaints. After 12--96 months (median 38 months) of ILP, 21 patients (29%) had thyroid surgery because of an unsatisfactory result. All had benign histology. Thyroid function was unaltered throughout and side effects were restricted to mild local pain.

Conclusion

US-guided ILP results in a satisfactory long-term clinical response in the majority of patients with a benign solitary solid cold thyroid nodule. Further large-scale studies should aim at optimizing selection criteria for ILP, preferably in randomized studies.
In vitro transforming potential, intracellular signaling properties, and sensitivity to a kinase inhibitor (sorafenib) of RET proto-oncogene variants Glu511Lys, Ser649Leu, and Arg886Trp
Authors: Prazeres Hugo , Couto Joana P , Rodrigues Fernando , Vinagre João , Torres Joana , Trovisco Vitor , Martins Teresa C , Sobrinho-Simões Manuel , Soares Paula
Published: May 2011

Multiple endocrine neoplasia type 2 and a subset of apparently sporadic medullary thyroid carcinoma (AS-MTC) are caused by germ line activating point mutations of the rearranged during transfection (RET) proto-oncogene. RET encodes a receptor with tyrosine kinase activity that targets several intracellular signaling cascades, such as RAS–RAF–ERK1/2, PIK3–AKT, and STAT transcription factors. The objective of this study was to assess the function of three germ line RET variants Arg886Trp, Ser649Leu, and Glu511Lys of undetermined pathogenic significance, which were found in three kindreds of isolated AS-MTC. For this purpose, we employed vectors expressing each of the RET variants and measured the number of NIH3T3 transformation foci and soft agar colonies, the degree of activation of known RET intracellular signaling targets (ERK1/2, STAT1, STAT3, and TCF4), and the extent of ERK1/2 inhibition on sorafenib treatment. We found that RET variants Arg886Trp and Glu511Lys have shown increased in vitro transforming potential in a glial-derived neurotrophic factor-dependent manner. In contrast, the Ser649Leu variant did not significantly increased the number of foci and agar colonies relative to wild-type RET (RET-WT). The variants Glu511Lys and Arg886Trp showed 10- and 12.5-fold ERK1/2 activation respectively, that was significantly higher than that observed for RET-WT (fivefold). Increased levels of STAT1 and TCF4 activation were only observed for RET Arg886Trp (2.5- and 3-fold versus 1.2- and 2-fold in RET-WT respectively). The three RET variants analyzed here were sensitive to treatment with sorafenib. In conclusion, our results allow to classify previously uncharacterized RET genotypes, which may be of use to define follow-up and therapeutic regimens.
Primary pulmonary epitheloid haemangioendothelioma
Authors: Pálföldi Regina , Radács Marianna , Csada Edit , Rózsavölgyi Zoltán , Tiszlavicz László , Somfay Attila , Gálfi Márta
Published: May 2011

A 49-year-old female patient was admitted in July 2009 because of cough, weight loss and effort dyspnoe. Chest X-ray and CT showed multiple bilateral nodules which have been identified earlier and these nodules were unchanged. However, there was a new parenchymal lesion in the right upper lobe, and new right hilar and mediastinal lymphadenomegaly was also found. Sample was taken by bronchoscope and the pathological diagnosis was pulmonary epitheloid haemangioendothelioma. This rare endothelial tumor usually affects middle-aged patients with a female predominance and it presents with chest pain, effort dyspnoe, cough, sputum, or it may remain asymptomatic. Multiple bilateral nodules are usually detected by radiologic examination. The diagnosis of this tumor is often challenging and, because of its rarity, it does not have any standard therapeutic regimen. Treatment can be surgery, chemo-, radio-, hormone- or immunotherapy. In order to find the most effective anticancer treatment, authors performed in vitro studies. On the basis of the results, chemotherapy was initiated which resulted in a partial regression. Orv. Hetil., 2011, 152, 834–839.
Thromboembolism and antithrombotic management in pregnancy
Authors: Pajor Attila
Published: May 2011

Venous thromboembolism occurs approximately in 1 of 1000 pregnancies. It is one of the leading causes of maternal mortality. Physiologic changes associated with pregnancy and delivery favor for developing venous thromboembolism, and there are individual risk factors, too, contributing to its manifestation. The most frequent risk factors of venous thromboembolism developing during pregnancy are the previous venous thromboembolism and the thrombophilias, furthermore, some other diseases and some unique complications of pregnancy and delivery. Beyond mechanical prevention only heparin preparations can be used for preventing and treating venous thromboembolism in pregnancy and among them the low-molecular-weight heparins are preferred for applying. Dosage of low-molecular-weight heparin preparations is determined by the type and strength of thrombophilia. For treatment of venous thromboembolism presented during pregnancy subcutaneous 100 IU/kg low-molecular-weight heparin is generally used at every 12 hours. Postpartum the oral anticoagulants can be safely applied, too. Orv. Hetil., 2011, 152, 815–821.
Attitude of medical students to regulatory measures related to tobacco smoking
Authors: Tóth Ildikó , Rinfel József , Oberling János , Prugberger László , Nagy Lajos
Published: May 2011

In some countries strict tobacco control measures successfully reduced the number of smokers. Although these measures do not have immediate effects, they may serve as investments in the future healthcare. Health care experts should take part actively in the decision making. Aims: To investigate medical students’ relation to smoking and their attitudes about tobacco control measures. Methods: Authors applied the Hungarian translation of the Global Health Professionals Student Survey. Medical students from the first and fifth year filled in the survey anonymously during the seminars. Statistical analysis was performed with SPSS. Results: Altogether 245 students completed the questionnaire. It was found that the knowledge of students about health damages caused by tobacco smoking was very good. However, a large number of students are exposed to tobacco smoke (68% of them at home and 85% at public places). Their opinion about tobacco control measures reflects recent law, as only 43% of the students would support a smoking ban in bars and discotheques. Conclusions: Hungarian health care experts have to take part with more effort in the prevention of tobacco smoking. Medical students have to be trained in this field. Orv. Hetil., 2011, 152, 828–833.
Sandstone Reservoir Stimulation Using High-Temperature Deep-Penetrating Acid
Authors: Feng Puyong , Wang Da , Liu Gangzhi , Wang Hongbin , Economides Michael J.
Published: May 2011

Conventional mud acid (a mixture of HF and HCl) is the most commonly used acid system for the stimulation of sandstone formations. However, well known disadvantages such as fast reaction rate, precipitation and matrix deconsolidation restrict the usefulness of this type of acid.

A high-temperature deep-penetrating acid system (HTDP acid) is presented in this paper. Compared with regular mud acid, the HTDP acid penetrates deeper into the formation by generating HF at a slower rate in situ. HTDP acid is one type of retarded mud acid, and it is made up of composite phosphate and fluoride salt. A new corrosion inhibitor has been developed which makes HTDP acid suitable for formations with temperatures as high as 356°F. Very important, the HTDP acid has much higher quartz solubility compared with the mud acid and could reduce precipitation.

The HTDP acid has been used in 23 wells in China offshore oilfields since 2006, and 22 of the stimulation jobs have been deemed effective. Among those wells, five are high temperature/low permeability wells (the highest temperature is 293 °F) and are located in China's Bohai Bay. Two of the wells are in a loose sandstone formation in the South China Sea. The production of these wells after stimulation was enhanced remarkably.

Though developed and used in China, the acid together with the high temperature inhibitor could be extrapolated to other similar sandstone reservoirs world-wide.
Studying the Breaking Mechanism of Polymer-Based In-Situ Gelled Acids using Solid Breaker
Authors: Tian Z. , Gomaa A. M. , Nasr-El-Din H. A.
Published: May 2011

In-situ gelled acids that are based on polymers have been used in the field for several years as an acid diversion agent. These acid should not cause permanent formation damage, and should clean-up rapidly and completely when the well is put back on production. However, recent lab studies indicated that a significant amount of gel retained inside the core even when the recommended breaker concentration was used. This gel significantly reduced the core permeability. Therefore, the objective of this study is to examine the working mechanisms of the solid breaker and the factors that effect on the breaking time. Temperature (150 to 250°F), shear rate (0.1 to 1000 s−1), and breaker concentrations (0 to 16 lb/Mgal) were the main parameters that were investigated in this study.

Experimental studies were conducted using polymer-based in-situ gelled acids that used Zr as a crosslinker agent. To form the gel, this acid was neutralized using pink desert limestone to pH 4.5. Then, the rheological properties of the gel were measured under different breaking conditions for 2 hr using HPHT rotational and oscillatory rheometers. To the best of our knowledge, this is the first time that the elastic properties were measured for these acids during the breaking.

Experimental results showed breaker concentration of 16 lb/Mgal was recommended at temperature equal to 150°F, while 4 lb/Mgal is enough at temperature higher than 200°F. A full breaking of these acids was obtained when the values of elastic modulus (G') were equalized with the viscose modules (G"). By shearing only the gel, the viscosity was reduced by 40% after 2 hr. The same viscosity reduction was obtained after adding 4 lb/Mgal of solid breaker without shearing. However, Shearing and adding 4 lb/Mgal breaker completely broke the gel after 40 min. With no shearing, in-situ gelled acid was fully broken after 45 min when 4 lb/Mgal breakers used at 250°F. However at lower temperatures, no full break was observed, but reduction in viscosity and in elastic modulus were noted. As the breaker concentration increased the elastic modulus decreased while the viscous modulus was increased.
Offshore Accidents, Regulations and Industry Standards
Authors: Visser Robert C.
Published: May 2011

Major offshore accidents, like the Macondo blowout, receive an enormous amount of publicity and are instrumental in enacting new and/or revised industry standards and governmental regulations. This paper reviews four major offshore accidents that occurred prior to 1988, and the effect that these accidents had on improving the reliability and safety of offshore operations. There had not been any significant offshore accident in more than twenty years. The absence of accidents, coupled with technological advances in being able to drill and produce in ever deeper waters, had gradually changed the public's perception of the safety of offshore drilling and had lessened the opposition for exploration in new offshore areas. All this has come to a halt with the 2010 Macondo blowout. The industry, unprepared to rapidly contain the Macondo blowout, will now be subject to new regulations and be required to develop a rapid containment capability.

The paper summarizes how regulations and industry standards evolved prior to 1988. Oil spills caused by drilling blowouts resulted in improved drilling procedures and regulations. Platform accidents caused by fires and explosions in process facilities resulted in mandatory subsurface safety valve requirements, regulatory inspection and compliance programs, the API RP 14C process facility reliability standard and the voluntary, now mandatory, SEMP program. Accidents in the North Sea led to regulatory requirements for platform risk management programs. The implementation of these regulations and industry standards resulted in significant improvements in the reliability and safety of offshore operations as evidenced by the absence of significant accidents over the past two decades. The paper also summarizes the background of the 2010 Macondo blowout and the new U.S. government regulations that will affect future offshore drilling and production operations in the Gulf of Mexico.
Modeling Fractured Horizontal Wells As Dual Porosity Composite Reservoirs – Application to Tight Gas, Shale Gas and Tight Oil Cases
Authors: Brohi Imad , Pooladi-Darvish Mehran , Aguilera Roberto
Published: May 2011

Multiply-fractured horizontal wells are an efficient way to produce from tight gas, shale gas and tight oil formations. In this work, we present a linear composite model with a dual porosity inner zone to model production from a multiple fractured horizontal well. The composite solution uses linear dual porosity flow solution for the inner reservoir and a linear single porosity solution for the outer reservoir combined with continuity of pressure and flux at their interface. Solution to the problem was obtained in Laplace space. The solution that we have obtained is simple and fast, yet effective and can be applied to model production from fractured horizontal wells.

For the cases of interest, we observe three linear flow periods in this model. The first linear flow is from the fractures into the wellbore, followed by linear flow in the matrix to the fractures and lastly linear flow in the outer single porosity reservoir to the inner reservoir. Each of these three linear flow periods is separated by a transition depending on the properties of the fracture, matrix and the outer reservoir.

We use a numerical simulator to examine the validity of some of the assumptions made in the development of the work. While the model that we have made consists of only linear flow solutions, the numerical model accounts for two dimensional flows in all media. New solutions are presented in the form of type curves.
The Effects of Wall Slip in a Couette Rheometer When Measuring and Comparing Hydraulic Fracturing Fluids
Authors: Churchill Scott
Published: May 2011

The most common apparatus to gather rheological properties on hydraulic fracturing fluids is the Couette rheometer. It functions by rotating a pressurized cup filled with a sample of the fluid around a bob. The rheometer calculates the apparent viscosity and power law values by measuring the friction between the bob, the fluid, and the cup based on the deflection of the bob at different shear rates of the rotating cup. With this sort of apparatus, the assumption is made that any "slippage" that the fluid encounters at the wall's surface is negligible. Although this assumption may be valid with other types of fluids such as those within the food or cosmetics industry, due to the unique characteristics of hydraulic fracturing fluids this is not always the case. Based on a rhelogical study of three different types of hydraulic fracturing fluids presented in this paper, conclusions were drawn on the effects of wall slip when measuring and comparing different types fracturing fluids and how this wall slipping phenomenon can be minimized. In this study three types of fracturing fluids were tested: a borate crosslinked water based gel, a surfactant water based gel and a hydrocarbon based gel. The water based gels demonstrated a significant amount of wall slip due to a phase separation of the water and gel. No phase separation was found in the hydrocarbon based fracturing gels, as such no wall slippage was observed. Several different metals were tested with varying surface roughness in order to attempt to minimize slip. Non-corrosive metals with a roughened surface allowed for higher viscosity readings in the water based gels. The surface roughness played a minimal effect in the viscosity readings for hydrocarbon based gels.
Viscosity Reduction EOR with CO2 & Enriched CO2 to Improve Recovery of Alaska North Slope Viscous Oils
Authors: Ning Samson , Jhaveri Bharat , Chambers Bret , Jia Na , Gao Jinglin
Published: May 2011

Carbon dioxide can be used as an injectant in Viscosity Reduction Water-Alternating-Gas (VRWAG) Enhanced Oil Recovery process for viscous oil reservoirs. The design of a VRWAG process with CO2 requires a series of laboratory data in order to properly understand the CO2 / reservoir fluid phase behavior and accurately model the reservoir performance. This study involved both laboratory experiments and reservoir simulation to investigate the effect of the phase behavior of the oil-CO2 system on the recovery of the Alaska North Slope viscous oils.

The laboratory experiments includes two four-step backward multiple-contact experiments (MCE) with pure and enriched CO2 added to Alaska North Slope viscous oil to investigate the phase behavior of the mixtures of CO2 and live reservoir fluid. The enrichment was achieved by mixing 85% of CO2 with 15% of natural gas liquids (NGL). Experiments were performed to determine the fluid compositions and other pressure-volume-temperature (PVT) properties such as saturation pressure, gas/oil ratio, liquid phase viscosity, and k-values under reservoir temperature and pressure conditions to simulate the dynamic behavior of the VRWAG process in viscous oil reservoirs. Precipitation of asphaltenes associated with the increase of carbon dioxide concentration and the number of contacts was also investigated.

The MCE experiments showed that pure CO2 could reduce the oil viscosity from 122 cp to 17 cp and that NGL-enriched CO2 could reduce the oil viscosity from 122 cp to 6 cp. These experimental data were used to verify a newly developed equation of state (EOS) which was then used in a numerical simulation model to predict the performance of CO2 flood process in viscous oil reservoirs. Simulation results showed that the VRWAG process could increase oil recovery factor by 10 percentage points with pure CO2 and 11 percentage points with NGL-enriched CO2, which represent an improvement of 44% and 50% respectively over the waterflood process.
Implementing Integrated Solutions for Reservoir Management: San Joaquin Valley Case Study
Authors: Popa Andrei , Horner Katie , Cassidy Steve , Opsal Steve
Published: May 2011

To achieve more efficient business processes by exploiting data and knowledge management, real-time systems and advanced analytical tools, most major integrated and service companies have developed, or are in the process of developing, intelligent programs also known as Digital Oil Field of the Future3. The i-field™ program represents Chevron's efforts to integrate people, processes, technology and information to achieve its vision of Upstream Transformation. Ultimately, this vision translates to higher-quality decision making and changes the way we operate our assets.

A new multiyear i-field™ program, Integrated Reservoir Management (i-RM), was initiated in the San Joaquin Valley to enable efficient reservoir management (RM) and quality decision making for heavy oil assests operating under steamflood EOR technologies.

The paper describes the journey undertaken by the project team to build a proprietary steamflood integrated reservoir management tool that answers the basic neverending engineering requirements: instant access to clean data, single source of information for everyone and seamless data-tools linkage. The ultimate benefit is not only increased time spent by engineers and earth scientists to analyze data but also consistent project design workflows and decision making processes across fields. In addition to above documented benefits, the manuscript includes operator's experience with project framing, development, deployment and user-acceptance.
Programs Enable Operational Excellence in a Challenging Environment, Pushing the Limits of Large Data Transfer for Real Time Monitoring and Surveillance Operations in San Joaquin Valley
Authors: Popa Andrei , Barrett Mark , Cassidy Steve
Published: May 2011

Chevron's San Joaquin Valley (SJV) Business Unit (BU) is a mature, heavy oil, thermally enhanced asset consisting of large fields that have been producing for over a century. To ensure continuing technology transformation, in 2003 San Joaquin Valley started its own i-field program being among the first BUs to pursue Chevron's enterprise-wide effort in building the Digital Oil Field of the Future. From its initiation, the program has been focusing on creating solutions to manage and optimize operations and enhance recovery.

The paper showcases one of the most technologically advanced i-field heavy oil solutions implemented in San Joaquin Valley thermal assets, involving a high accuracy tiltmeter program implemented by a partner service company to advance the understanding of diatomite operations and monitor the surface ground movement

In 2008, Chevron's SJV i-field team partnered with its Information Technology (IT) department to develop a state-of-the-art application called Integrated Diatomite Operations Tool (i-DOT). The product incorporated current field workflows for mapping the grid deformation with business data (well locations and status, steam volumes and dates, etc.) in relevant time. This was accomplished by establishing a live connection between Chevron and partner service company servers whereby terabytes of grid data would flow seamlessly into Chevron's SJV servers. Data acquisition, data processing and storage efforts were accomplished through an integrated effort between IT, GIS and PetroWeb development teams. Workflows were built through close collaboration between i-field engineers, petroleum engineers, earth ecientists, IT professionals and the operations group.

The i-DOT solution has become the single point of operation monitoring and activity scheduling for multiple groups such as Operations, Asset Development and the Drilling team. The benefits of implementing i-DOT solutions are significant and transformed our decision making process in diatomite fields. The paper includes not only value creation but also lessons learned during development, deployment and end-user acceptance.
A Data Mining Approach to Unlock Potential from an Old Heavy Oil Field
Authors: Popa Andrei , Cassidy Steve , Mercer Mark
Published: May 2011

This paper presents an integrated lookback approach on analyzing historic reservoir performance in a California asset using data driven technologies. Being characterized as a heavy oil asset, with oil gravity between 6 to 12 API, a wide range of cyclic steam practices combined with diluent injection was used to produce the field. Drilling and cyclic steam activity in the field reached a peak in 1984 followed by a sharp decline in 1986 due to low oil prices.

A set of data mining tools including regression, clustering techniques, and neural networks was used in the study to understand past operation practice and performance. In the first stage, using well locations, completion data, production history, and target sand depths zonal allocations of production was estimated. The second stage established the cyclic steam response of the different formations. Along the way, data driven tools were used to identify the common and best practices in the field.

The data driven technologies and tools used in this study proved to be a fast and thorough approach for examining large data sets and extracting powerful knowledge. This approach was applied and executed in a portion of a heavy oil field in California and provided the fundamental understanding for future re-entering and development of the asset.
Application of Case-Based Reasoning for Well Fracturing Planning and Execution
Authors: Popa Andrei , Wood William , Cassidy Steve
Published: May 2011

Over the last two decades, there has been significant activity in the soft computing arena with focus on various computer paradigms such as neural networks, genetic algorithms, and fuzzy logic to more efficiently solve complex engineering problems. Further work concentrated on integrating two or more of these paradigms has led to what is known as "hybrid systems." The power of the hybrid system relies on the fact that technologies are intended to complement each other and exploit their individual strengths to enhance solution generation.

Case-based-reasoning (CBR) is another soft computing technology developed to deal with uncertainty, approximate reasoning and exploit knowledge domain. Case-based reasoning, also known as computer reasoning by analogy, is a simple and practical technique that solves new problems by comparing them to ones that have already been solved in the past, thus saving time and money.

This paper provides a general framework of case-base reasoning along with a review of the four-step cycle that characterizes the technology (retrieve, reuse, revise and retrain), followed by a specific application to well fracture treatment design, planning and execution. The proposed methodology extracts the relevant historical information recorded during field job execution, utilizes a rule-based system to make adaptations, and then suggests the most appropriate solution for new well fracturing candidates. The technique was tested as a front-end tool using sample data from a tight gas field with significant hydraulic fracturing activity. This simple case demonstrates how case-base reasoning can be applied to improve hydraulic fracturing design, planning and execution of wells, thus significantly increasing the job execution success while avoiding known pitfalls. In addition, the work demonstrates the value of captured "on-site" experience and shows the advantages of using intelligent systems in decision making.
A High-Resolution Approach in Predicting Reservoir Performance from Diatomite
Authors: Akhimiona Nosa , Corbett Patrick W. , Lewis Ken
Published: May 2011

Managing a waterflood in a diatomite reservoir faces a number of challenges, such as oil recovery, performance matching, optimum well spacing and subsidence. Another issue is the paucity of studies done on the diatomite reservoir, as most studies in petroleum engineering are based on the performance of more conventional clastic /sandstone or carbonate reservoirs. So, applying some of these concepts in a diatomite reservoir can lead to erroneous results. A better understanding of the relationship between the geology and reservoir performance cannot be overemphasized, especially where the reservoir is a diatomite reservoir with no known analogue.

Improving the recovery from diatomite reservoirs has been a problem since first production in the 1890's. In 2007, horizontal wells were drilled in the Lost Hills field and supported with vertical water injectors to improve recovery. These wells are fractured hydraulically to improve drainage and conductivity. However, the oil production performance results from these wells were below expectation. Some of the wells watered out, others were fraught with ‘sanding’ and other operational issues. This study looks at effective ways of scaling kv/kh which is critical to matching production performance.

A good numerical model that incorporates understanding of the geology proved important to be able to predict performance from wells. The geopseudo approach, a multiphase flow upscaling methodology, is used in this study. It incorporates flow/structure interaction at the lamina level. The conclusions and recommendations from this study will provide an insight through which petroleum engineers will be able to build a robust simulation model needed for predicting well performance and also help in making data driven decisions with respect to field development.