bluuebunny/crossref_metadata_2025_split huggingface dataset:
Curing Lost Circulation in Fractured Reservoirs Using a Level-Off Cement Plugging Method- Case Studies in Drilling and Workover Applications
Authors: Ashena Rahman , Ghalambor Ali , Hekmatinia Abdol-Azim 
Published: February 2020

Abstract
Controlling lost circulation during drilling operations in a reservoir prone to losses is typically remedied by cement squeezing or plug setting. The aim being to minimize or stop drilling fluid losses and to regain full returns at surface, and to affect wellbore integrity. Different placement methods of cement plugs have been discussed in detail in the literature, except for the ‘level-off’ method, which is particularly effective for curing complete loss circulation cases. Following the mathematical modeling of this cement plug placement method, its design, procedure and execution are discussed, together with some successful field cases, both drilling and workover situations in highly-fractured carbonate reservoirs in the Middle East.
Using drill pipe and an installed a Retrievable-Test-Treat-Squeeze (RTTS) packer, with some spacing from the loss zone, the method entails that the cement slurry is allowed to drop by gravity in order to cure lost circulation. As the column of fluid, mud and slurry in the well exceeds formation pore pressure, i.e. overbalanced conditions, a volume of acid-soluble cement slurry is allowed to slowly drop and freely penetrate the formation, i.e. through its fractures or caverns. During the penetration of this viscous slurry into the loss zone, the cement can set and the fracture or fissure openings are plugged. In addition, to minimize or prevent further losses, this cementing technique may also mitigate formation damage of adjacent zones.
Presented are detailed design calculations for the level-off placement technique: determination of required cement slurry and displacement volumes, and recommended displacement and RTTS packer setting depths. The expected depth of the top of cement is estimated. The design parameters are compared with field cases and explanations are given for possible discrepancies. Detailed field procedures and execution are also presented.
This is the first known, detailed description and modelling of the level-off cement placement technique in the literature.
Effects of Kaolinite on Fines Migration and Formation Damage
Authors: Prempeh Kofi , Chequer Larissa , Badalyan Alexander , Bedrikovetsky Pavel 
Published: February 2020

Abstract
The presence of residual oil or gas during fines migration in porous media greatly affects particle mobilization and capture. This paper investigates the effects of kaolinite content on fines migration and formation damage in the presence of oil residual. We carried out corefloods on engineered sand-packs that contained different percentages of kaolinite. Each core sample was subjected to brine injections varying from seawater salinity to freshwater. Measurements of the pressure drop and effluent particle size distributions were performed for each injection. It was determined that the main cause of permeability decline was pore throat straining by kaolinite. A higher decline of permeability accompanied by intensive fines production was encountered during freshwater injection. If compared with fines migration under single-phase flow, having a residual phase showed a significant decrease in formation damage and the amount of produced kaolinite. The laboratory data were matched with the analytical model for one-dimensional linear flow. A close agreement between the coreflood data and the model was obtained. The model coefficients were used for well injectivity decline prediction using a numerical one-dimensional radial injection model. The kaolinite content and the residual oil phase greatly impacted the well injectivity decline.
A Concise Review of Experimental Works on Proppant Transport and Slurry Flow
Authors: Roostaei Morteza , Nouri Alireza , Hosseini Seyed Abolhassan , Soroush Mohammad , Velayati Arian , Mahmoudi Mahdi , Ghalambor Ali , Fattahpour Vahidoddin 
Published: February 2020

Abstract
Final proppant distribution inside hydraulic fractures which depends on particle properties, movement and deposition highly impact wellbore productivity and consequently is crucial in modeling and design of hydraulic fracturing. This paper presents a thorough review of laboratory scale tests performed on proppant transport related to hydraulic fracturing treatments and governing physics behind its mechanisms.
The interaction between fluid (gas and liquid) and solid particles has been investigated in applied mathematics and physics. In such phenomena, there is always a relative motion between particles and fluids. In this work this relative motion during proppant movement, sedimentation and fluidization in both small- and large-scale lab tests have been assessed in detail. Existing correlations which relate proppant particles settling velocity to concentration of proppant particles, fracture wall and inertia effect in Newtonian and non- Newtonian fluid are presented as well.
Lab tests show that various parameters determine the proppant particles distribution inside the fractures. Particle settling velocity, an influential parameter in this regard, is impacted by fracture walls, inertia and the presence of other particles. Inertia changes the relation of drag coefficient and Reynold number. Fracture wall and particles concentration decrease settling velocity as drag force increases. At a certain level, concentration reaches to its limit. Proppant concentration, in addition, increases the suspension viscosity, fracture width and net pressure. However, it deceases the fracture length as more pressure loss occurs along the fracture. As a result, well productivity is highly impacted by the proppant settling and distribution.
Many studies have been devoted to identifying different aspects of hydraulic fracturing and proppant transport mechanisms in porous media. This study highlights the key parameters and their effects, existing correlations and physics behind them for better understanding and management of this mechanism.
Successful Application of Non-Damaging Drill-In-Fluids Proves Oil Production Improvement in Heavy Oil Reservoirs
Authors: Kalhor Mohammadi Mojtaba , Tahmasbi Nowtarki Koroush , Ghalambor Ali 
Published: February 2020

Abstract
Production of heavy oil reservoirs are increasing due to the limitation in conventional resources. Despite the availability of different technologies and methods for recovery and enhancing the oil production from heavy oil reservoirs, we need to consider the oil production from these reservoirs with their particular rock and fluid chemical characteristics to prevent serious formation damage during drilling the reservoir. Heavy oil is intend to build strong microemulsions that blocks the reservoir pores. Unfortunately, this concept is missed and the heavy oil properties and its viscosity are considered as the main problems. This paper studies the formation damage and mitigation in heavy oil reservoirs.
Drilling fluid is the first non-indigenous fluid to contact the formation and thus, it provides the first opportunity for causing permeability damage. The key point in formation damage control is to minimize the invasion zone into the reservoir section. Controlling the chemical reactions between invaded fluid type and heavy oil along with the changes in rock properties plays an important role in emulsion blocking which is the main cause of formation damage in these reservoirs. In addition, we need to consider other parameters such as lithology and shale dispersant which can be the other source of damage to plug the porous media.
Both Laboratory pilot tests and field application proves the effect and performance of drill-in-fluid in the heavy oil reservoirs. The designed high performance reservoir compatible drilling fluid replaced oil based mud which reduced formation damage by keeping the production index at acceptable and higher level comparing to previously drilled wells. Furthermore, the paper discusses the designed criteria including formulation, properties and applications of the fluid in detail by comparing lab and field data to prove the effect of Drill-in-Fluid effect on the well production performance.
It was observed that the high performance, reservoir compatible drilling fluid system, successfully minimized formation damage by minimizing fluid loss invasion into the reservoir comparing with conventional OBM with lower skin factor. This recorded a higher productivity index up to 10 times which is a unique achievement without stimulation. The oil production rate of the nominated well increased more than that of the nearby wells.
Impact of Oil Saturation, CO2 Evolution, and Rock Wettability on Acid Efficiencies During Carbonate Acidizing: A Three-Phase Perspective
Authors: Kumar Harish T. , Muhemmed Sajjaat , Nasr-El-Din Hisham A. 
Published: February 2020

Abstract
Success rates of carbonate acidizing, when upscaling from single, aqueous-phase laboratory analyses to field scale levels have been poor. Analyzing matrix acidizing performances in carbonate reservoirs with two-phase environments. i.e., oil and water, has picked up importance currently in the stimulation industry. A lack of understanding of the mechanisms taking place in this complex subsurface process still exists, particularly with carbon dioxide (CO2) evolution from limestone dissolution, and the presence of a secondary fluid phase in the medium.
A detailed investigation via experimental core studies and fluid modeling / characterization has been performed for oil/water environments in the porous media. Moderate permeability carbonate cores, with an average of 14% porosity were used for this study. Six acidizing experiments with 15 wt% hydrochloric (HCl) acid were performed using outcrop Indiana limestone cores, at temperatures of 150°F and initial pore pressures of 600 and 1,200 psi. The presence of a light crude oil in the cores at residual conditions was tested for acid efficiencies in un-aged and aged conditions. Rock wettability measurements via contact angle experiments, and oil/water interfacial tension, σow, measurements were conducted, and the effects of CO2 to alter the rock-wettability, oil/water interfacial tensions, was studied. Characterization of the crude oil was performed using Equation of State based simulations, and the behavior of CO2-crude oil systems were evaluated via simulated minimum miscibility pressure and swelling tests.
Cores with residual oil at water-wet conditions yielded the least acid pore volumes to breakthrough (PVbt), at all tested pore pressures. An increased oil-wetness of the rock resulted in greater acid PVbt's, when compared to water-wet systems with both residual oil and fully water saturated cores. CO2's capability to alter rock-wettability did not show any benefits toward improving acid efficiencies in cores at residual oil saturations, Sor. The acid efficiencies in porous media containing oil and water largely depend on the access of sufficient rock surface to the acid species, for which rock-wettabilities are a governing factor.
A Comprehensive Rheological Study for a Flowing Polymer-Based Drilling Fluid Used for Wellbore Strengthening
Authors: Magzoub Musaab Ibrahim , Salehi Saeed , Hussein Ibnelwaleed Ali , Nasser Mustafa Saleh 
Published: February 2020

Abstract
Loss circulation encountered in highly fractured formations, depleted reservoir, or HP/HT intervals is the root cause of many problems plaguing the oil and gas sector for many years. High pore pressure narrows the window of safe drilling, while in depleted reservoir fracture pressure is remarkably reduced, which may lead to a lower pressure-bearing capacity. Therefore, a proper predrill wellbore strengthening strategy is needed to anticipate wellbore issues and design drilling fluids that strengthen unstable formations.
This study benefits from the successful applications of polymers in water shut-off. Whereas polymers are used to entirely plugs high water productive zones, the flowing polymer-based mud (PBM) is proposed and evaluated to enhance wellbore strengthening. Based on the API drilling fluids testing procedures, varied polyacrylamide/polyethyleneimine PAM/PEI systems were tested and ammonium chloride (NH4Cl) is added as a retarder to control gelling time as need. Base fluid formulated with PAM/PEI was optimized to attain the desired rheological properties. Weighting and other commercial essential additives were also added, and the formula is tested for rheology, stability, and sealing efficacy.
Our proposed PBM formula with proper concentration of polymer in water and optimized PAM to PEI ratio is found to be highly competitive in comparison with the conventional methods of loss circulation prevention and wellbore strengthening techniques. This paper introduces an innovative design for a flowing polymer-based mud (PBM) for wellbore strengthening and provides wide-range of assessment. Moreover, the essential rheological characteristics revealed in this study for several PAM/PEI mud systems under various conditions can set the stage for wide application of these muds globally where tremendous reduction in drilling non-productive time (NPT) can be achieved.
Aquaporin 3 Expression Pattern in Gastric Diseases and its significance
Authors: Li Heng , Dai Xudong , Dou Jin , Xu Hualin , Min Qi , Zhu Lun , Li Yuewu , Zhuang Haiwen , Zhang Xiaoyu , Zhao Haijian 
Published: February 2020

Abstract
Background

Aquaporin 3(AQP3) has been implicated in gastric intestinal metaplasia and gastric cancer, and considered as a biomarker to improve treatment strategy. Accumulating evidence suggests that AQP3 is involved in the gastric carcinogenesis and the disease progression. However, whether AQP3 is involved in the transformation from gastritis to gastric cancer remain elusive. In this study, we intended to realized the expression pattern and its significance of AQP3 in different gastric diseases.

Methods

A total of 101 patients diagnosed with gastric diseases were included in the study. A gastric tissue biopsy was taken from the gastric antrum during endoscopic examination. Expression of AQP3 protein is determined by immunohistochemistry using polyclonal rabbit anti-AQP3 antibody. Percentage of positive cells and staining intensity were counted and measured.

Results

The frequency of AQP3 positivity was similar between the disease types of chronic gastritis, gastric ulcer, gastric erosion, and atrophic gastritis, whereas the frequency of AQP3 positivity was significantly higher in patients with gastric intestinal metaplasia、gastric dysplasia 、gastric polyps and intestinal-type gastric adenocarcinoma than that in patients with gastritis, gastric ulcer, gastric erosion, or atrophic gastritis(p<0.0001, p=0.001, p=0.006, p=0.0009, respectively), especially in the patients with hyperplastic polyps (p<0.0001).

Conclusion

The frequency of AQP3 positivity was significantly higher in patients with gastric intestinal metaplasia, gastric dysplasia, and gastric adenocarcinoma, and the frequency between them was similar, suggesting that AQP3 expression is peaked at the stage of gastric intestinal metaplasia, which further confirmed that gastric intestinal metaplasia is a pivotal progression in gastric carcinogenesis pathologically. Interestingly, it is the first time to report AQP3 positive expression in patients with gastric polyps. In short, AQP3 is involved in the progression from gastritis to gastric adenocarcinoma, and might be a potential biomarker to improve the treatment strategy of gastric cancer.
The Occupational Sitting and Physical Activity Questionnaire (OSPAQ): a validation study with objective accelerometer registrations
Authors: Maes Iris , Ketels Margo , Dyck Delfien Van , Clays Els 
Published: February 2020

Abstract
Background: The Occupational Sitting and Physical Activity Questionnaire (OSPAQ) was developed as an easy-to-use instrument for self-reported assessment of percentage sitting, standing, walking and performing heavy labour in a workplace setting. This study aimed to evaluate the criterion validity of all dimensions of the OSPAQ compared to objective accelerometer measures of occupational physical activities in a mixed sample of sedentary and physically active professions. Methods: Data from the Flemish Employees’ Physical Activity (FEPA) study were used, including employees from the service and production sector. All participants filled in a questionnaire, underwent clinical measurements, and wore two accelerometers for at least 2 consecutive working days. Intra-class (ICC) and Spearman rho correlations (r) were analyzed to assess criterion validity. Results: The sample included 401 workers (16% sedentary profession) with a mean age of 39.2 (± 11) years. Criterion validity was good and moderate for assessing percentage of sitting (ICC=0.84; r=0.53), and standing (ICC=0.64; r=0.53), respectively. The criterion validity for walking was weak to moderate (ICC=0.50; r=0.49), and weak for performing heavy labour (ICC=0.28; r=0.35). Stronger validity scores were found in sedentary professions for occupational sitting and standing. In physically active professions, an underestimation of self-reported sitting and standing was found, and an overestimation of self-reported walking and heavy labour. No significant self-reported over- or underestimation was found for sitting and heavy labour in sedentary professions, but an underestimation of self-reported standing (p<0.001) and an overestimation of self-reported walking (p<0.001) was observed. Conclusions: The OSPAQ has acceptable measurement properties for assessing occupational sitting and standing. Objective measurements of occupational walking and heavy labour are recommended, since a poor criterion validity was found for both.
Overexpressed LncRNA ADAMTS9-AS2 inhibited gastric cancer (GC) development and sensitized chemoresistant GC cells to cisplatin by regulating miR-223-3p/NLRP3 axis
Authors: Ren Niansheng , Jiang Tao , Wang Chengbo , Xie Shilin , Xing Yanwei , Piao Daxun , Zhang Tiemin , Zhu Yuekun 
Published: February 2020

Abstract
Background The role of LncRNA ADAMTS9-AS2 in the regulation of pathogenesis and chemoresistance of gastric cancer (GC) is largely unkonwn, and this study aimed to solve this problem. Methods Real-Time qPCR was used to examine LncRNA ADAMTS9-AS2 and miR-223-3p expressions, and pearson correlation analysis was conducted to analyse their correlations. Kaplan-Meier survival analysis was performed to evaluate prognosis of GC patients. Dual-luciferase reporter gene system and pull-down assay were employed to validate the target sites of LncRNA ADAMTS9-AS2, miR-223-3p and NLRP3 mRNA. Cell viability was evaluated by CCK-8 assay, trypan blue staining and colony formation assay. Cell apoptosis ratio was detected by FCM and TUNEL assay. Transwell assay for cell migration and Western Blot for protein expressions. ELISA was used to measure cytokines secretion. FISH was conducted to examine LncRNA ADAMTS9-AS2 expressions and localization in mice cancer tissues. Results LncRNA ADAMTS9-AS2 was low-expressed in GC tissues and cells compared to their normal counterparts. Besides, LncRNA ADAMTS9-AS2 inhibited miR-223-3p expressions in GC cells by acting as competing endogenous RNA, and the levels of LncRNA ADAMTS9-AS2 and miR-223-3p showed negative correlations in GC tissues. Of note, overexpression of LncRNA ADAMTS9-AS2 inhibited GC cell viability and motility by sponging miR-223-3p. In addition, the levels of LncRNA ADAMTS9-AS2 were lower, and miR-223-3p was higher in cisplatin-resistant GC (CR-GC) cells than their parental cisplatin-sensitive GC (CS-GC) cells. LncRNA ADAMTS9-AS2 overexpression enhanced the cytotoxic effects of cisplatin on CR-GC cells, which were reversed by overexpressing miR-223-3p. Furthermore, LncRNA ADAMTS9-AS2 increased NLRP3 expressions by targeting miR-223-3p, and upregulation of LncRNA ADAMTS9-AS2 triggered pyroptotic cell death in cisplatin treated CR-GC cells by activating NLRP3 inflammasome through downregulating miR-223-3p. Finally, the promoting effects of LncRNA ADAMTS9-AS2 overexpression on CR-GC cell death were abrogated by pyroptosis inhibitor NSA.Conclusions LncRNA ADAMTS9-AS2 acted as a tumor suppressor and enhanced cisplatin sensitivity in GC cells by regulating miR-223-3p/NLRP3 axis mediated pyroptosis.
Community composition and functional genes as well as ecological role of bacteria attached to different bloom-forming cyanobacteria
Authors: Song Chunlei , Yang Liu , Cao Xiuyun , Chen Xiaoyan , Deng Qinghui , Wan Lingling , Li Xiaowen , Zhou Yiyong 
Published: February 2020

Abstract
Background

Eutrophication leads to frequent outbreaks of cyanobacterial blooms, especially those of the genera Dolichospermum and Microcystis. The contribution of bacteria attached to algal cells to cyanobacterial blooms is still not clear and specific. To gain a deeper understanding of functional genes and their role in bacteria attached to different bloom-forming cyanobacteria, we carried out microbial experiments associated with Dolichospermum and Microcystis in four fish ponds.

Results

The significantly positive relationships between Dolichospermum density and total nitrogen (TN) and between Microcystis density and particle nitrogen (PN) indicated the strong nitrogen (N) demand of these two species. The lack of functional genes mediating the nitrification process in bacteria attached to both Microcystis and Dolichospermum indicated that these two species preferred ammonium (NH 4 + -N). Dolichospermum could overcome N limitation through N 2 fixation expressed by high nitrogenase genes abundance. Compared to bacteria attached to Dolichospermum cells, bacteria attached to Microcystis cells showed a higher activity of leucine aminopeptidase (LAP) and a significantly higher abundance of functional genes (such as nrfA , nirB and aminopeptidase genes) mediating the dissimilatory nitrate reduction to ammonium (DNRA). The significantly higher abundance of functional genes (carbon degradation) and β-glucosidase (GLU) activity of bacteria attached to Microcystis than those of bacteria attached to Dolichospermum suggested the abundant organic carbon bound Microcystis cells, which was prerequisite for DNRA. Also, Microcystis had a great advantage in solving phosphorus (P) stress, including high levels of organic phosphorus hydrolysis associated with high levels of phosphatase genes of attached bacteria. The difference of functional community compositions of bacteria attached to Microcystis and Dolichospermum resulted in the functional differentiation.

Conclusions

Dolichospermum and Microcystis growth was susceptible to P and N (especially NH 4 + -N) limitation, respectively, the latter of which could be effectively solved by attached bacteria through DNRA and ammonification. The P acquisition disadvantage of Dolichospermum resulted in its frequent replacement by Microcystis , especially in conditions of P deficiency. Hence, the evaluation of nutrient limitation (N or P) type of algal growth should combine the nutrient concentration and ratio as well as the ability to solve nutrient deficiency.