bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative evaluation of nutrient media of Escherichia coli isolating for using in veterinary laboratories
Authors:   Central Scientific and Methodological Veterinary Laboratory, Moscow, Russian Frderation, Skomorina Yu.A. , Kremleva A.A. ,   Central Scientific and Methodological Veterinary Laboratory, Moscow, Russian Frderation, Akhmetova L.Sh. ,   Central Scientific and Methodological Veterinary Laboratory, Moscow, Russian Frderation, Podolskaya T.V. ,   Central Scientific and Methodological Veterinary Laboratory, Moscow, Russian Frderation, Shepelin A.P. ,   State Research Center for Applied Microbiology and Biotechnology, Rospotrebnadzor, Obolensk, Moscow Region, Russian Federation, Polosenko O.V. ,   State Research Center for Applied Microbiology and Biotechnology, Rospotrebnadzor, Obolensk, Moscow Region, Russian Federation
Published: May 2021

The article is focus on comparative studies of modern differential diagnostic nutrient media for effective cultivation and identification of Escherichia coli. The assessment of the quality of media by biological properties was carried out in accordance with their purpose. Special attention is paid to the new generation of differential diagnostic nutrient media. It was found that the tested media have high productivity and inhibitory properties. New culture media of inland producers are not inferior in terms of the characteristics declared by the manufacturers. In case of methods validation the veterinarian laboratory will be able to use new nutrient media. Key words: nutrient media, Escherichia, productivity, selectivity and specificity
Results of monitoring of biological safety requirements in veterinary laboratories
Authors:   State Research Center for Applied Microbiology and Biotechnology, Rospotrebnadzor, Obolensk, Moscow Region, Russian Federation, Chekan L.V. , Tyurin E.A. ,   State Research Center for Applied Microbiology and Biotechnology, Rospotrebnadzor, Obolensk, Moscow Region, Russian Federation
Published: May 2021

Results from monitoring biological safety in veterinary microbiological laboratories of various levels of protection are under consideration. An algorithm to monitor compliance with biological safety requirements for working conditions, engineering and technical support and protection of the laboratory employee health is adapted. Violations of biological safety requirements identified during the monitoring of veterinary laboratories of various levels of protection, where employees work with microorganisms of Groups II–IV pathogenicity (danger), are studied. Measures to improve the biological safety status are available. Keywords: veterinary laboratory, monitoring, analysis, biological safety
CRISPR/Cas-Systems: characteristics and possibilities of use for editing bacterial genomes
Authors:   Moscow State Institute of Physics and Technology (National Research University), Dolgoprudny, Moscow Region, Russian Federation, Blatov I.A. , Shchurova A.S. ,   Moscow State Institute of Physics and Technology (National Research University), Dolgoprudny, Moscow Region, Russian Federation, Guschin D.Yu. ,   Moscow State Institute of Physics and Technology (National Research University), Dolgoprudny, Moscow Region, Russian Federation, Zvereva S.D. ,   Moscow State Institute of Physics and Technology (National Research University), Dolgoprudny, Moscow Region, Russian Federation, Popova A.V. ,   Moscow State Institute of Physics and Technology (National Research University), Dolgoprudny, Moscow Region, Russian Federation,   State Research Center for Applied Microbiology and Biotechnology, Rospotrebnadzor, Obolensk, Moscow Region, Russian Federation
Published: May 2021

CRISPR-Cas is the adaptive immune system of bacteria and archaea. Since 2012, when the first opportunity to use the CRISPR/Cas system for genome editing was realized, the number of studies in this area has been growing rapidly. Today, genomic editing to modify specific regions of the genomes of various organisms is considered one of the key methodologies of modern biology. This review is devoted to the history of discovery, classification, structure, operational mechanisms of CRISPRCas systems and strategies for editing the genomes of various bacterial species using this technology. Key words: genome editing, genome, CRISPR-Cas system, bacteria
Morphological aspects of microbial biofilm formation on atherosclerotic plaque fragments
Authors:   A.I.Evdokimov Moscow State University of Medicine and Dentistry, Moscow, Russian Federation, Tsarev V.N. , Nikolaeva E.N. ,   A.I.Evdokimov Moscow State University of Medicine and Dentistry, Moscow, Russian Federation, Vitovich M.V. ,   A.I.Evdokimov Moscow State University of Medicine and Dentistry, Moscow, Russian Federation, Podporin M.S. ,   A.I.Evdokimov Moscow State University of Medicine and Dentistry, Moscow, Russian Federation, Ippolitov E.V. ,   A.I.Evdokimov Moscow State University of Medicine and Dentistry, Moscow, Russian Federation
Published: May 2021

Modern research indicates the presence of living bacteria in atherosclerotic plaques. However, the potential of microbes in the formation of biofilms in arterial plaques has not been studied. Purpose of the study. Identification of biofilms on fragments of arterial vessels with atherosclerotic plaques. Materials and methods. Fragments of atherosclerotic plaques isolated during coronary artery bypass grafting in patients with coronary artery disease were cultured in an exhaustive fluid system under anaerobic conditions in vitro for 1 or 14 days. The presence of biofilms was evaluated using scanning electron microscopy. Results. Mixed biofilms, represented by rod-shaped bacteria and cocci, were identified after in vitro cultivation in all fragments of atherosclerotic plaques. The characteristic ultrastructure revealed the main stages of the biofilm life cycle. Conclusions. Modeling biofilms on biotic surfaces in a system of exhausted fluids under anaerobic conditions will allow us to study in detail the phenotype of biofilms and provide a significant understanding of the pathophysiology of infectious processes in blood vessels and atherosclerotic plaques. Key words: atherosclerotic plaque, chronic periodontitis, biofilm-forming microbes, periodontal pathogens, causative agents of nosocomial infections, fluid technology
Development of candidate vaccines against infection caused by shiga-toxin producing Escherichia coli. Part 2
Authors:   State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, Russian Federation, Svetoch E.A. , Dyatlov I.A. ,   State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, Russian Federation, Kartsev N.N. ,   State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, Russian Federation, Eruslanov B.V. ,   State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, Russian Federation, Kanashenko M.E. ,   State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, Russian Federation, Fursova N.K. ,   State Research Center for Applied Microbiology and Biotechnology, Obolensk, Moscow Region, Russian Federation
Published: May 2021

Prevention and treatment of hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS) caused by Shiga-toxin producing Escherichia coli (STEC) continues to be a public health concern. The main reason for the problem is the lack of vaccines and lack of evidence for using of antibacterial etiotropic drugs to treat this infection. A promising scientific approach to create specific agents against STEC infection is the development of subunit recombinant vaccines. The analysis of experimental studies presented in this review shows that effective subunit vaccines against STEC infection can be created on the basis of known immunogenic determinants of HC and HUS causative agents – EspA, EspB, and Tir proteins, intimin, as well as H7 antigen of E. coli O157:H7 and nontoxic proteins of Shiga toxins Stx1 and Stx2 A and B subunits. Using these epitopes, three types of subunit vaccines are designed: antibacterial vaccine, vaccine protecting the macroorganism from systemic intoxication caused by Shiga toxins, and vaccines that simultaneously induce the antibacterial and antitoxic immunity. Since the epitopes listed above are weak immunogenic, to increase their immunogenicity, complex chimeric antigenic structures containing protein inducers are constructed that significantly increase the immune response to target specific epitopes. Mineral adjuvants are also widely used to increase the immunogenicity of STEC epitopes. All three types of created candidate subunit vaccines, at subcutaneous, intramuscular and intranasal application induce production of specific IgG and secretory IgA antibodies in animals and protect them from the infection caused by the STEC strains. Key words: STEC, hemorrhagic colitis, immunodominant antigens, Shiga toxins, EspA, EspB, Tir, intimine, IgG, sIgA
Phytoncides: history and application prospects
Authors:   Academician I.N.Blokhina International Fund for Biotechnology, Moscow, Russian Federation, Chubatova S.A. ,   LLC «ERBI», Moscow, Russian Federation
Published: May 2021

A brief informational material on the history of the use of phytoncides in medical practice over the past few centuries and the results of our own research on the study of the properties of new drugs based on phytoncides in liposomes is proposed. The effectiveness of phytoncides use for 20 years within the framework of the «Indoor Airspace Ecology» program indicates that this direction is promising. Key words: phytoncides, liposomes, antibacterial agents
Determination of sensitivity of microorganisms of the Klebsiella genus to antimicrobial drugs by the MALDI-TOF MS method
Authors:   Pasteur Research Institute of Epidemiology and Microbiology, Saint Petersburg, Russian Federation, Samoilova A.A. , Likhachev I.V. ,   Pasteur Research Institute of Epidemiology and Microbiology, Saint Petersburg, Russian Federation, Zueva E.V. ,   Pasteur Research Institute of Epidemiology and Microbiology, Saint Petersburg, Russian Federation, Rogacheva E.V. ,   Pasteur Research Institute of Epidemiology and Microbiology, Saint Petersburg, Russian Federation, Kraeva L.A. ,   Pasteur Research Institute of Epidemiology and Microbiology, Saint Petersburg, Russian Federation,   S.M.Kirov Military Medical Academy, Saint Petersburg, Russian Federation, Mikhailov N.V. ,   Pasteur Research Institute of Epidemiology and Microbiology, Saint Petersburg, Russian Federation
Published: May 2021

Actual microbiological diagnostics of infections caused by Klebsiella spp. should include isolation of the strain, its identification and fastest possible determination of the pathogen susceptibility to antimicrobial agents. We evaluated the prospects of using MALDI-TOF mass spectrometry to determine the susceptibility of Klebsiella spp. strains to antimicrobial agents. According to the results of mass spectrometry Klebsiella spp. strains analysis, we carried out cluster analysis by the UPGMA method based on mass spectra and data on the susceptibility of the studied strains to antimicrobial agents, and then studied the obtained dendrograms. We identified the areas with the highest probability of the location of antibiotic resistance markers by comparing the mass spectra of susceptible and resistant microorganisms at different concentrations of antimicrobial agents. Thus, using MALDI-TOF mass spectrometry, a new direction in assessing the susceptibility of Klebsiella spp. to antimicrobial agents can be formed. Key words: antibiotic resistance, Klebsiella spp., MALDI-TOF mass spectrometry
Ways to solve problems of Proteus isolation in veterinary medicine
Authors:   Central Scientific and Methodological Veterinary Laboratory, Moscow, Russian Federation, Kremleva A.A. , Skomorina Yu.A. ,   Central Scientific and Methodological Veterinary Laboratory, Moscow, Russian Federation, Polosenko O.V. ,   State Research Center for Applied Microbiology and Biotechnology, Rospotrebnadzor, Obolensk, Moscow Region, Russian Federation, Shepelin A.P. ,   State Research Center for Applied Microbiology and Biotechnology, Rospotrebnadzor, Obolensk, Moscow Region, Russian Federation
Published: May 2021

When studying isolates from waste of processing animal meat products and mechanically deboned meat the comparative analysis of nutrient media was done. The assessment of the growth of bacteria of the genus Proteus on the media based on such parameters as productivity, differentiating and inhibiting properties. Of special interest is a new highly selective nutrient media tested in the veterinary laboratory. It has been shown that the domestic differential diagnostic medium to isolate bacteria of the genera Proteus, Morganella, and Providencia is characterized by high productivity and significant inhibitory properties to be used in veterinary medicine to analyze any material contaminated with proteins along with concomitant bacteria. Key words: veterinary medicine, nutrient media, Proteus, differentiating properties, selectivity
The role of earthworms in the spread of anthrax
Authors:   State Research Center for Applied Microbiology and Biotechnology Rospotrebnadzor, Obolensk, Moscow region, Russian Federation, Marinin L.I. , Shishkova N.A. ,   State Research Center for Applied Microbiology and Biotechnology Rospotrebnadzor, Obolensk, Moscow region, Russian Federation, Mokrievich A.N. ,   State Research Center for Applied Microbiology and Biotechnology Rospotrebnadzor, Obolensk, Moscow region, Russian Federation, Dyatlov I.A. ,   State Research Center for Applied Microbiology and Biotechnology Rospotrebnadzor, Obolensk, Moscow region, Russian Federation
Published: May 2021

The article discusses the issue of the danger of earthworms in the spread of anthrax in connection with the long-term persistence of the causative agent of the disease in the soil of cattle burial grounds. The results of assessing the effect of earthworms on soil cleansing from the anthrax pathogen and the properties of microorganisms isolated from worms are presented. Studies have shown that under the influence of worms, the amount of anthrax pathogen in the soil decreases by 30–50%, but the remaining spores did not change their properties and retained all the main biological and genetic factors of pathogenicity. Key words: earthworms, anthrax causative agent, spore culture, cultivation
Obtaining bunny hyperimmune serum for Haemophilus influenzae
Authors:   CJSC «EKOlab», Elektrogorsk, Russian Federation, Neskorodov Ya.B. , Mishutkina Ya.V. ,   CJSC «EKOlab», Elektrogorsk, Russian Federation, Mardanlу S.G. ,   CJSC «EKOlab», Elektrogorsk, Russian Federation,   State University of Humanities and Technology, Orekhovo-Zuevo, Russian Federation
Published: May 2021

This brief report describes the approaches and results of obtaining rabbit hyperimmune sera for Haemophilus influenzae. Key words: Haemophilus influenzae, hyperimmune serum, agglutination
Holistic and reductionist thinker : a comparison study based on individuals’ skillset and personality types
Authors: Nagahi Morteza , Jaradat Raed , El Amrani Safae , Hamilton Michael , Goerger Simon
Published: May 2021

As organizations operate in turbulent and complex environments, it has become a necessity to assess the systems thinking (ST) skills, personality types (PTs), and demographics of practitioners. In this study, we investigated the relationship between practitioners’ ST profile, their PTs profiles and demographic characteristics in the domain of complex system problems. The objective of this study is to address the current gap in the literature – lack of studies dedicated to predicting practitioners’ ST profile based on their PTs and demographics characteristics. A total of 258 practitioners with different demographics and PTs provided the data. The results show that (1) practitioners can be classified based on their ST skills scores into two clusters: holistic and reductionist (that is, ST profile), (2) each cluster has different PTs profiles and demographic characteristics, and (3) practitioner’s ST profile can be predicted, with good accuracy, based on their PTs profile and demographic characteristics.
Exceeding Technical Limit for Drilling and Completing Complex Wells by using an Optimized Flat-Rheology Mud Formulation: A Comprehensive Overview
Authors: Alomair Abdullah Abdulaziz , Cuellar Hugo Fernando , Kashwaa Mohamed , Sharma Sunil
Published: May 2021

Horizontal sections drilled in conditions that require high mud densities to prevent wellbore collapse are very challenging from both drilling engineering and drilling fluid management point of views. Due to drilling complications, nonaqueous fluids (NAFs) are the best suitable drilling fluids of choice for drilling complex and long horizontal sections. From the other side, as nonacid soluble weighting materials cannot be used while drilling some reservoir sections, which are completed with open screens in open hole, using calcium carbonate is the most economical and best preferred acid soluble/nondamaging option to formulate these fluids.

When the density requirements reach above 90 lb/ft3 (12 lb/gal) while using calcium carbonate in the NAFs, fluid formulations exhibit high rheological values due to excessive solids. High solids loading and improper fluids engineering in these high-density ranges lead to hole instability and differential sticking issues in addition to extreme difficulties in managing completions screens runs. These challenges can severely limit the well depth or increase the operation time, impacting profitability of whole project; failing to tackle even one of them could result in catastrophic failure.

To overcome above associated challenges, a flexible novel flat rheology invert emulsion system formulation was introduced, which was customized for sustaining high solids loading while maintaining its signature flat-rheology profile. This system uses new technology emulsifier and rheology modifier package for achieving flat-rheology independent of temperature and pressure changes. The fluid formulation was implemented in the area by loading the mud system with more than 330 pounds per barrel of calcium carbonate for reaching densities up to 99 lb/ft3 (13.25 lb/gal).

This paper will present a comprehensive overview of novel technology, the steps taken from planning to execution, the overall performance-based results, the cost effectiveness of the new solution, and the challenges during implementation. The troubleshooting steps taken are also discussed for all the challenges that occurred while drilling.
Temporary Isolation of a Prolific Open Hole Gas Zone using a Non-Damaging Methodology - A Multi-Well Case Study in a Field of Kurdistan N. Iraq
Authors: Looten Kristopher A , Raza Mustansar
Published: May 2021

Objectives/Scope

A case study is presented detailing the methodology used to place a non-damaging temporary isolation barrier in a group of naturally fractured, prolific gas wells in a field in Kurdistan. The temporary isolation facilitated removal of the original completion string and installation of the redesign. Wells were returned to production with-out the need to stimulate proving success of the non-damaging methodology employed.

Methods, Procedures, Process

The operator had 4 wells with OH sections ranging from 33-181m which were completed in the 1980’s - 1990's with no production packer. In order to preserve well bore integrity the completion string needed to be pulled and replaced by a string with production packer and DH gauges. A procedure was developed to fill the highly fractured OH with a mixed particle size CaCO3 carried into the wellbore by a non-damaging surfactant based gel. Caliper logs were not available and the presence of natural fractures posed a challenge to calculating the actual OH volume. A system was developed to carry the CaCO3 into the wellbore in stages and slickline was employed to measure fill after each stage. Once the OH was filled with CaCO3 and well would support a fluid column coil tubing was used to place an acid soluble cement plug in the short interval between casing shoe and end of tubing (8-10m)

Results, Observations, Conclusions

The first well in the campaign required more than 10 times the theoretical volume of CaCO3 to fill the open hole. It was concluded the surfactant gel was likely carrying the CaCO3 into the fractures. The procedure was modified to tie in a line of breaker solution to the well head allowing sufficient viscosity of the fluid to carry the CaCO3 from surface but immediately lose viscosity and allow the CaCO3 to settle in the wellbore without being carried into the formation. Specific coil tubing procedures were employed to allow the setting of ultra-short acid soluble cement plugs (<10m). All wells were successfully isolated to allow the safe workover of the completion string and returned to production with no loss of gas flow, with-out the need to stimulate after the work over.

Novel/Additive Information

The campaign exhibited a new method of employing existing technologies to achieve the objective in a highly challenging and relatively new oilfield of Kurdistan. The campaign also demonstrated the benefit of the operator and service company closely collaborating on each step of a novel process. The workovers would not have been successful with-out the close collaboration of the two companies.
Lean Rig-Less and Explosiveness Abandoning in Morocco
Authors: Baumgardner Lonny , Ahamiri Jamal , Kuyken Chris , Farouk Mohamed , Jammeli Kamel , Merchan Ylmer
Published: May 2021

A 5-well rig-less & explosiveness abandonment campaign by 2 project partners operator and service provider was made a reality in Morocco whereby a novel method of cementing squeeze of perforations and an annular fill-up were established in one single operation.

This is called LEAN abandonment and the method was masterminded as a result of intense collaboration between both partners. The method is scale-able and has full merit to target existing legacy wells for abandonment in Morocco and world-wide where appropriate.

In this LEAN approach the tubing and annulus were communicating via SSD / non-explosive created tubing punch by holding backpressure on the annulus till perforations squeezed or pressure lock-up and subsequently immediately opening the annulus and releasing the annular pressure whilst continuing pumping and filling the annulus with some 800 m of cement creating the firm additional barrier.

Clinical planning by operator and service provider on a establishing a new abandonment process that is opening-up further in-country and beyond opportunities was the critical success factors in this work. It led to organic improvement on a well by well basis in the campaign, it resulted in safe and successful operations and achieving abandonment objectives cementing to surface in tubing and annulus.

LEAN Abandonment forms a paradigm shift. It may be different in different down-hole settings and there is no single solution however like in our case working a bottoms-up approach has resulted the lowest cost solution and having done so ways to improve overall safety and efficiency were identified. The use of non-explosive technology is a very good example.
The Axial Agitation System Effect on Rotary Steerable Drilling: ADNOC Offshore Mature Field Case Study
Authors: Gohel Prashant , Al-Kasasbeh Ameen , Subramanian Meenakshi , Ary Wahyudi , Mohamed Nowfal
Published: May 2021

The drilling industry faces several challenges related to downhole vibration; amongst the solutions introduced to alleviate those challenges, a unique Axial Agitation System is often considered. This paper qualitatively analyses the effect of the Axial Agitation System in directional drilling and quantifies how it addresses the above challenges observed in Rotary Steerable System (RSS) Bottom Hole Assembly (BHA) used in the 8.5 in. section in different wells of the ADNOC Offshore mature field.

The Axial Agitation System consists of Axial Oscillation Tool which generates a pressure pulse from a valve driven by mud flow converted to axial motion by The Shock Tool. The system complements the rotational movement of the string by introducing gentle and consistent axial oscillating motion. The drill string moves around its rotational axis, oscillating along its axial axis reducing kinetic frictional losses from interaction with the wellbore, especially in directional and long lateral sections.

The analysis consisted in comparing drilling dynamics metrics between wells with AAS in the drill string and offset wells without it, in the 8.5in hole section. As a pilot project, the system was introduced into Well A. Based on the successful tests in the pilot well; the system was also utilized in Wells B & C. The metrics include, but are not limited to, drilling activities, surface mechanical indicators, downhole data from the RSS as well as mathematical modelled algorithms. The results of the analysis of wells clearly indicate an enhancement into the drilling dynamics in terms of overall reduction in kinetic friction, improved weight transfer, less hanging and levels of torsional dynamics, shocks and vibration. The collateral benefits also included performance improvement, reduced non-productive time (NPT) and lower mechanical specific energy (MSE) to drill the section. The Axial Agitation System complemented very well with the rotary steerable system as well as other BHA components and delivered consistent performance in all three wells.

High amplitude fine-tuned Axial Agitation System paired with RSS BHA creates a combination of a highly efficient directional system. The results are consistently performance with reduction in the shock and vibration levels in the environment. This also benefits in improving tool reliability, directional control while also optimizing the repair and maintenance costs for the downhole tools.
A Matrix Acidizing System for Controlled Carbonate Well Stimulation using a Carboxylic Acid Salt with a Chelating Agent
Authors: Bokkers Albert , Brandenburg Piter , Lare Coert Van , Kooijman Cees , Schutte Arjan
Published: May 2021

This work presents a matrix acidizing formulation which comprises a salt of monochloroacetic acid giving a delayed acidification and a chelating agent to prevent precipitation of a calcium salt. Results of dissolution capacity, core flood test and corrosion inhibition are presented and are compared to performance of 15 wt% emulsified HCl.

Dissolution capacity tests were performed in a stirred reactor at atmospheric pressure using equimolar amounts of the crushed limestone and dolomites. Four different chelating agents were added to test the calcium ion sequestering power. Corrosion tests were executed using an autoclave reactor under nitrogen atmosphere at 10 barg. Core flood tests were performed to simulate carbonate matrix stimulation using limestone cores.

It was found that the half-life time of the hydrolysis reaction is 77 min at a temperature of 100 °C. Sodium gluconate and the sodium salt of D-glucoheptonic acid were identified to successfully prevent the precipitation of the reaction product calcium glycolate at a temperature of 40 °C. Computed Tomography (CT) scans of the treated cores at optimum injection rate showed a single wormhole formed. At 150 °C an optimum injection rate of 1 ml/min was found which corresponds to a minimum PVBT of 6. In addition, no face dissolution was observed after coreflooding. Furthermore, the corrosion rates of different metallurgies (L80 and J55) were measured which are significantly less than data reported in literature for 15wt% emulsified HCl.

The novelty of this formulation is that it slowly releases an organic acid in the well allowing deeper penetration in the formation and sodium gluconate prevents precipitation of the reaction product. The corrosivity of this formulation is relatively low saving maintenance costs to installations and pipe work. The active ingredient in the formulation is a solid, allowing onsite preparation of the acidizing fluid.
Drilling the Un Drillable: A Case Study of the Bela Well in Makran Accretionary Prism
Authors: Baig Umair Ahmed , Agha Ghulam Nabi
Published: May 2021

The Bela Well is situated on Makran accretionary prism with several active mud volcanoes that makes conventional drilling challenging due to the extremely high pore pressure i.e. in excess of 15,000 psi and a very narrow window between pore pressure and fracture pressure. This adverse condition was observed in the 9 offset wells drilled within this basin with problems related to wellbore instability, lost-circulation zones and over-pressured formations leading to kick/loss well control scenarios that resulted in the well being abandoned prior to reaching the geological target.

The constraint to drill the planned and 8-3/8" section in the well was the unpredictability of the pore/fracture pressure in the Panjgur formation representing a high-level operational risk. Solutions to tackle such a high pressure well included incorporating heavy grade casing i.e. 9-7/8"- 72 ppf in the planning stage, utilization of a 3000 HP rig to cater to extreme axial and hydraulic loads. Whereas MPD was planned as a technique to cater to the narrow window between pore pressure and fracture pressure.

A managed pressure drilling (MPD) system was utilized to enable drilling the 8-3/8" hole section. An MPD system that applies constant bottom hole pressure enabled drilling the section with statically underbalanced mud weight by keeping a constant surface back pressure to prevent any influx. The drilling window for MPD was validated by determining the Bottom Hole Pressure where both, an influx from the formation and fluid losses occurred. These values were later used to establish the target Equivalent Circulating Density-ECD to drill the hole accordingly. Trips for BHA change or BOP test were performed by placing a pressurized mud cap in the wellbore.

This paper describes in detail the successful MPD application resulted in the first well being drilled in the Makran accretionary prism to a depth of 5000 m. Lessons learned and challenges encountered will also be discussed in this paper
Selection of Biopolymers and Lubricants to Mitigate Stabilization of Gas/Air Entrapment in ERD Wells: Offshore Abu Dhabi
Authors: Haddad Mohamed , Alwahedi Khalid Ahmed , Al Hilali Osama Mohamed , Cesetti Maurizio , Benygzer Mhammed , Husien Mohammad , Allogo Clotaire-Marie Eyaa , Cholakkaparamban Naseerali , Barcan Armand , Rasheed Ami
Published: May 2021

The paper will present lessons learnt to mitigate the stabilization of the air/gas entering into lubricious biopolymer water-based system which decreased density of mud while drilling. The system selected for its highly lubricious properties and formation damage free properties to accommodate the usage of resistivity equipment provided excellent results in the field. Performance was almost equivalent to non-aqueous drilling fluid. However, the stabilization of gas/air entering the mud was encountered generating drilling troubles and risk of well control problems.

An extensive study performed, consisted of assessing interactions between components and containments of the mud system with gas/air, crude-oil and drill solids introduced from the reservoir. The testing involved the adding of air from air-compressor for 60-second while mud sample is sheared at 6000 rpm. The mud weights of samples were measured before addition of air, right after and 60-second after the aeration. The percentage of density drop was calculated. Target value was maximum drop of 5% within 60 second after stopping the addition of air. Several combinations of polymers, lubricants, contaminants and other additives were evaluated.

The study demonstrated that the interactions between crude-oil, polymers and lubricants can highly stabilize air/gas entrapment in the biopolymer water base mud system. The phenomena led to significant density decrease, drilling troubles, well control and safety issue in the field. They can also increase the viscosity of the biopolymer mud system. However, highly stabilized air/gas entrapment can be removed by the addition of emulsion breaker at concentration less than 1.5%vol of mud. In addition, the type and nature of the lubricant plays a major role in the stabilization of air/gas entrapment. The selection of the polymers should be combined with the choice of lubricant during the design phase to minimize the gas entrapment.

Knowledge gained from the study establish a new testing protocol to assess in the laboratory the air/gas entrapment close to field shear conditions. The testing protocol showed good correlation with the field. The testing protocol can be used during the design phase or for investigations. It will improve the overall design of mud system where highly lubricious fluid is needed. Combination of polymers and lubricants did also provide low air/gas entrapment tendency.
Application of Resin-Cement Blend to Prevent Pressure Build-Up in Casing to Casing Annulus CCA: A Novel Approach to Improve Well Integrity
Authors: Ali Wajid , Mata Freddy Jose , Hashmi Ahmed Atef , Al-Yami Abdullah Saleh
Published: May 2021

Assurance of well integrity is critical and important throughout the entire well's life cycle. Pressure build-up between cemented casings annuli has been a major challenge all around the world. Cement is the main element that provides isolation and protection for the well. The cause for pressure build-up in most cases is a compromise of cement sheath integrity that allows fluids to migrate through micro-channels from the formation all the way to the surface. These problems prompt cementing technologists to explore new cementing solutions, to achieve reliable long-term zonal isolation in these extreme conditions by elevating shear bond strength along-with minimal shrinkage. The resin-cement system can be regarded as a novel technology to assure long term zonal isolation. This paper presents case histories to support the efficiency and reliability of the resin-cement system to avoid casing to casing annulus (CCA) pressure build-up.

This paper presents lab testing and application of the resin-cement system, where potential high-pressure influx was expected across a water-bearing formation. The resin-cement system was designed to be placed as a tail slurry to provide a better set of mechanical properties in comparison to a conventional slurry. The combined mixture of resin and cement slurry provided all the necessary properties of the desired product. The slurry was batch-mixed to ensure the homogeneity of resin-cement slurry mixture. The cement treatment was performed as designed and met all zonal isolation objectives. Resin-cement’s increased compressive strength, ductility, and enhanced shear bond strength helped to provide a dependable barrier that would help prevent future sustained casing pressure (SCP).

The producing performance of a well depends in great part on a good primary cementing job. The success of achieving zonal isolation, which is the main objective of cementing, is mainly attributed to the cement design. The resin-cement system is evolving as a new solution within the industry, replacing conventional cement in many crucial primary cementing applications. This paper highlights the necessary laboratory testing, field execution procedures, and treatment evaluation methods so that this technology can be a key resource for such operations in the future.

The paper describes the process used to design the resin-cement system and how its application was significant to the success of the jobs. By keeping adequate strength and flexibility, this new cement system mitigates the risk of cement sheath failure throughout the life of well. It provides a long-term well integrity solution for any well exposed to a high-pressure environment.
Liquid Strength Retrogression Control Additive
Authors: Jadhav Rahul , Pisklak Thomas
Published: May 2021

To mitigate strength retrogression at temperatures, higher than 230°F, well cement designs typically include strength retrogression control additives (SRCAs). Solid siliceous materials (e.g., silica flour, fume, and sized-sands) are commonly used SRCAs that are incorporated into cements using dry-blending techniques. This study highlights liquid silica compositions as alternative SRCAs to dry-blended silica for high-temperature cementing. Liquid additives can be managed easily, delivered accurately, and offer a reduced on-site footprint, thus making them particularly advantageous for operations offshore and in remote locations.

This paper presents a study on the use of liquid silica compositions as SRCAs and their effect on cement slurry properties, such as thickening time, mixability, fluid loss, rheology, and free water. The cement slurry used during the current study was prepared and tested according to API RP 10B-2 (2005). The performance of the liquid silica composition was tested at temperatures up to 400°F. Set cement samples were prepared using the liquid silica composition and silica flour, cured for up to 14 days at different temperatures. In addition, permeability testing was also performed on the samples.

This paper presents the findings of this research, including strength and permeability test results on cement blends cured at temperatures of 300, 330, 350, and 400°F. The liquid silica composition, which provided silica to the cement formulation equivalent to 35% BWOC dry silica (48% BWOC liquid SRCA), functioned effectively as an SRCA at temperatures up to 330°F. Signs of strength retrogression were observed at 350°F and were more pronounced at 400°F. A greater concentration of the liquid silica composition may be necessary to prevent strength retrogression at temperatures higher than 330°F. The liquid silica composition also demonstrated mild retardation and a dispersing effect on the slurry. However, it helped enable improved slurry stability and suspension, thus providing improved control over free water without adverse effects on fluid loss and sedimentation.

The study results demonstrate that a liquid SRCA can help improve the performance of annular cement designs to provide dependable barriers and effective zonal isolation during high-temperature cementing applications. The improved performance enabled by this liquid silica composition verifies its potential use as an alternative SRCA for high-temperature oil well cementing operations.
New Methodology of Slot Recovery Minimizing Milling Operation
Authors: Sato Ryosuke , Abdelkarim Islam Khaled , Albeshr Abdul Rahman Hasan , Toki Takahiro , Al Ali Salim Abdalla , Alzaabi Mohamed Abdulrahman , Malpass Paul , Barbera Roberth
Published: May 2021

Slot recovery operation can be considered as one of the most time consuming operation. Cut and pull casings, or milling casings have been carried out as typical method of slot recovery. However there are a lot of risks with this typical method such as poor progress of milling, damaging top drive due to high vibration while milling or sudden string jumping up while overpulling and possibility of string stuck caused by poor hole cleaning while milling. We have completed slot recovery operations on numbers of wells, but there were a lot of troubles caused by above mentioned adversaries on rig equipment and taking a lot of time to complete operation.

There are several kinds of new slot recovery technologies that may save rig time and less harmful than conventional method. Casing Pulling Tool (CPT) is one of the new technologies which eliminates or mitigates risks mentioned above. CPT has piston internally and it is activated by applying pressure inside string. CPT is run with casing spear and drill pipes. Once spear is engaged with casing and apply pressure inside drill string, CPT provides pulling force on casing. Pulling force is varied depend on the applied pressure and maximum available pulling force is more than 1,000 kips. Hence upper part of string is anchored at rotary table by slips, pulling force is applied on casing and drill string below rotary table. This means no pulling force is applied on top drive and minimize the chance of getting damage on it.

As an actual case, we could successfully recover 13-3/8" casing by CPT without having any troubles and complete slot recovery operation with saving rig time compared to the conventional methods.

This paper introduces the details about the case mentioned above.
Production Casing Regains Integrity by Repairing Shallow Leak with Microfine Cement
Authors: Al-Khaldy Meshal , Al-Saadi Dhari , Al-Ajmi Mohammad , Al-Banai Mohammad , Elafify Ibrahim , Jaber Fajar , Al-Dakheel Rashed , AlBohamad Dalal , Ekwue Ann-Marie , Hussain Khadar , Kunchur Basavaraj , Svensen Dan
Published: May 2021

While carrying out planned workover activities, production casing had to be tested to verify integrity. A shallow leak was observed across the production casing at about 1000 ft MD from surface.

External and/or internal casing corrosion especially across relatively old wells, could lead to such inconsistency, moreover that major challenge to address and react such surprises online while operation meanwhile nothing to help as a pre-planning studies.

Further production objectives require casing integrity as per ESP design to protect shallow aquifer sources. Numerous attempts to repair the casing leak by performing remedial squeeze operations utilizing conventional cement slurry designs proved unsuccessful.

Other ideas were considered such as deploying a scab liner to cover the damaged casing section, however this was discounted as it would introduce undesirable borehole restrictions; as well as extra 6 days for running, cementing and clean-out.

A novel engineered approach with Microfine cement slurry design squeezed into the damaged zone successfully regained casing and well integrity, while maintaining full borehole access through the production casing, thus saving rig time and tangible cost.

Well drilling operations should be carefully designed and executed targeting the integrity assurance by providing the right casing metallurgy and good cementation for proper zonal isolation behind individual casing strings to mitigate external casing corrosion and act as the first line of defense against corrosion and any potential leakage or cross flow among different formations across the life span of the well.

Well completions should be installed / tested considering the protection of inner production casing / liner from getting in prolonged contact with wellbore fluids, to avoid excessive internal corrosion and achieve reservoir fluid containment across the life of the well.

A proactive approach been raised to acquire production casing / liners corrosion logs across workover activities especially regarding old wells to enable the mapping and interpretation of casing wall thickness / corrosion progress along the well life. That approach could aid in predicting the condition of production strings before commencing planned workover activity; and thus justify the availability of back-up repair plan to maintain rig operations and avoid any unscheduled operational surprises and possible strategic production rate defer.
Overcoming Thin Reservoir Geosteering using Advanced Technique in Sultanate of Oman
Authors: AlGhamdi Sarah Mohammed , Beche Amina , Awadalla Muhannad , Naamani Hafidh , Aljiroudi Fadi , Hashemi Alkhalil , Siyabi Khalid , Hooti Younis
Published: May 2021

Drilling long laterals within Shuaiba limestone reservoir without exit to Nahr-Umar shale in the challenging field "B" that is characterized by geological uncertainty can have major risks. The low to very low resistivity environment reservoirs are common in Oman especially while placing wells nearby OWC; on a reservoir spot window of 1-2m TVD only.

The main objective is to place the well less than 1m TVD below the reservoir top, this was achieved by utilizing Multilayer Bed Boundary Detection and Rotary Steerable System.

Integrating propagation resistivity curves response with the directional resistivity curves response from Bed Boundary detection tool have been used as a guide for an optimal well placement in low resistivity reservoir, along with Rotary Steerable System are one of the best strategies which have been used to place the wells within the right spot.

For tight geosteering window with an aggressive formation tendency pushing the azimuth left or right and continues inclination instability associated with the existence of an interbedded layers of hard streaks within the reservoir, a faster and more competent Rotary Steerable System tool and Bit selection is required, as proven it provides better stability results for achieving well placement objectives and respond in fast manner to geosteer in real time.

The objective of this paper is to describe the geosteering logging while drilling (LWD) technology and technique and Rotary Steerable system (RSS).
Advanced Wellbore Surveying Technology Extends the Drilling Limits in Offshore Operation
Authors: ElGizawy Mahmoud , Ness Knut , Kolakkodan Saleel
Published: May 2021

Wellbore surveying is critical while drilling in order to assure the drilled well is following the plan and is penetrating the geological target. Additionally, wellbore surveying is the key to allowing a well to be drilled safely, avoiding other wells drilled in the same field, and optimizing reservoir production. Standard wellbore surveying accuracy is increasingly inadequate for optimizing the well placement in real time to maximize the reservoir recovery due to maturity of the field. The other disadvantage of the standard wellbore surveying often requires running an additional wellbore surveying tool to improve the accuracy in order to manage the collision avoidance with nearby wells in the same field, introducing unwanted time and costs. Hence, this article presents the advanced wellbore surveying technology that is successfully implemented in offshore fields of Abu Dhabi to overcome the limitations of the standard surveying accuracy without compromising rig time.

Magnetic measurement while drilling (MWD) surveys are common standard and utilized in every directional well in this operation. To overcome the standard accuracy limitation, advanced survey correction to the magnetic MWD surveys is introduced. This includes in-field referencing to provide a higher resolution magnetic reference to calculate a more accurate well direction, correction to the effect of the steel components in the bottom hole assembly on the magnetic MWD surveys, correction to the errors associated with survey sensors calibration, and correction to any misalignment between the survey tool and the wellbore.

Correcting the surveys in real-time while drilling is the key to placing the well accurately and to avoid offset wells in the close proximity. The details of the corrections methodology are discussed. Advanced magnetic survey correction procedures in real-time are outlined and mapped out. Finally, results of improving the magnetic surveys while drilling in placing the wells and minimizing the collision risk of offset wells are presented. This advanced survey technology allows drilling previously un-drillable wells in these offshore fields, and the allowance for increased density of wells in the reservoir gives the operator opportunity to maximize production recovery and extend the life of reservoir.

Higher accuracy of wellbore surveys is an increasing requirement in mature fields to safely allow more accurately placed wellbores with the required production rates. This allows for improved well placement along the trajectory facilitating adjustment at control points and landing points to maximize the hydrocarbon production. In addition, it allows controlling the probability of collision with any nearby wells. The enhanced wellbore surveying accuracy is achieved by advanced magnetic survey corrections in real time. This is controlled by a stringent novel process and communication protocol in order to meet the accuracy objectives.