Thread Compounds Research Articles

Utilizing phased array ultrasound technique to examine seal surface contact status in premium connections

Premium connections are commonly employed in wells subjected to high temperature and high pressure (HTHP) conditions. The key parameter in evaluating the sealing capability of premium connections is the contact condition between the sealing surface. This paper presents a method based on phased array ultrasound testing (PAUT) technique to examine the metal-to-metal contact states of the seal surface in premium conditions, and presents experimental work on contact status of the seal surface in premium tubing connections using PAUT, testing impacts of torque, seal surface defects and thread compounds dosage. The experimental findings demonstrate an inverse relationship between the observed ultrasonic reflection amplitude and the applied torque on the premium. Additionally, there is a robust exponential correlation manifested between the ultrasonic reflection amplitude and the torque exerted on the premium. The ultrasonic reflection amplitude at the defect of the seal surface increases. Under equivalent make-up torque conditions, the ultrasonic reflection amplitude on the sealing surface of premium connections escalates as the dosage of thread compounds diminishes, and the importance of precise control of the amount of thread compound used was confirmed. These data demonstrate that PAUT provides a reliable detection technique for performance assessment on premium connections, both in quality control and field inspection.

A Preliminary Study on the Sublethal Effect of Greases Used in Oil Drilling Wells with Earthworms Assay

As a result of the world's dependence on oil, as well as the impact this production chain has on some producing countries. There is a certain carelessness when the objective is to reduce the impacts that the activity produces on the environment. Thus, investigations on chemical compounds used and produced by this industry are necessary and relevant. In order to identify possible toxic effects on organisms from terrestrial environments, this study analyzed the effects of Kendex OCTG and Jet Lube® Korr-Guard™ thread compounds on <i>Eisenia andrei</i> (earthworms). Standard NBR ISO 17512-1 - Soil Quality - Leakage test to assess soil quality and effects of chemical substances on behavior Part 1: Assay with earthworms (<i>Eisenia fetida</i> and <i>Eisenia andrei</i>) was used. In the earthworm escape, test only Kendex OCTG showed a sublethal effect similar to the reference compound, boric acid, while the tested worms Jet Lube® Korr-Guard™ showed attraction behavior. The ecotoxicological approaches showed that, regarding the sublethality parameter, no ecotoxicological risk was demonstrated in the Jet Lube® Korr-Guard™ dope, while the Kendex OCTG thread compound showed a sublethal to Eisenia andrei, representing this risk form for terrestrial organisms. We suggest further studies with other parameters (genotoxicity, neurotoxicity and cytotoxicity, for example) that may add more ecotoxicological information to these products.

Technical and Technological Aspects of Assessing the Quality Characteristics of Thread Compounds in Products from Fibrous Materials

The object of the study is thread connections of garments parts, and the subject is an express instrumental method and technical support for determining damage to threads by the needle of a sewing machine when sewing garments. The purpose of study is to develop technological and technical support for the process of researching the quality of the sewing stitch based on the development of an express method for determining damage to threads in a material when a needle is punctured during sewing, which increases the objectivity and accuracy of the estimated information. As a result of the study, a method for assessing the damage to a material by a needle during sewing was developed and a patentable technical device for its implementation is proposed. The developed method is based on the use of neural networks elements and provides for the control of visible and invisible needle cut in the process of sewing the product. The technical solution of the device provides the ability to visualize the sewing stitch through the use of optoelectronic means and the formation of an electronic database of material properties on-line. The developed method belongs to the class of express methods, provides new technological possibilities for studying the quality of thread compounds and increasing the objectivity of evaluating the characteristics under study. Testing of the proposed technological and technical solutions showed the necessary efficiency and the possibility of practical application of the developed method.

Physiological and biochemical parameters of apricot cultivars under drought conditions on the Southern Coast of the Crimea

In order to determine special features of the photosynthetic apparatus activity and the content of thread compounds in various apricot cultivars during the period of maximum drought probability on the Southern Coast of the Crimea, we studied the concentration of proline, phenolic compounds and chlorophylls, as well as the parameters of chlorophyll fluorescence induction (CFI) in some apricot cultivars ( Prunus armeniaca Lam.), characterized by various degree of drought tolerance (‘Alupkinsky’, ‘Krymskiy Amur’) are weakly resistant; Khurmai cultivar is characterized by labile resistance, and the cultivars Kazachok, Professor Smykov, Nagycorosi Orias are drought tolerant cultivars). It has been found out that drought-resistant cultivars are characterized by a relatively low content of proline in their leaves. It is supposed that this amino acid is involved in the protective reactions of apricot plants under water stress. The results of the photosynthetic apparatus studies in the presented cultivars demonstrated that in leaves, water loss less than 20% caused reversible changes in the parameters of CFI. An increase in the water deficit up to 25-30% caused the destruction of PS2 in weakly drought-resistant cultivars. The most stable photosynthetic apparatus activity was noticed in the cultivar Nagycorosi Orias. Deviations in photosynthesis processes were most pronounced during the period of water restoration in leaves.

Experimental investigations of thread compounds viscosity degradation towards long term threaded connections leak resistance

Oil and gas leakages represent the (functional) failure mode as a result of sealing failure of thread connections. With the expectation for more safer and efficient operations during the exploration and production phase of oil and gas fields, Oilfield Country Tubular Goods (OCTG) require the use of thread compounds (pipe dope) to lubricate tubular connections during installation, provision of high resistance to presence of galling and ascertain a consistent friction coefficient, thus importantly to improve the sealing performance of API standard connections or among other expectations. In the period of improvement and upturning procedures for thermal enhanced oil, high temperature fluids (around 300 °C) with the production wells having a lower production temperature.To characterize the long-term sealing performance of OCTG threaded connections, this paper presented the experimental comparative studies and, the effect of viscosity degradation of five different types of thread compounds for thread connections samples using a programmable digital rheometer device under influences of shear rate, temperature and different loading conditions. The experimental outcome shows a dramatical transformation of the tested five thread compound's viscosity and how their sealability performance is being compromised. In view of this, the tested samples showed that the reduced viscosity properties will impede the tubulars connection leak tightness and durability in most thermal well's development. Our results also revealed that particular samples do fail at low temperature condition (70 °C) as this may impinge on pipe connections behavior during the breakout operation.

A utilização de graxas em revestimentos durante a construção de poços de petróleo: análise de Fichas de Informações de Segurança de Produtos Químicos

A poluição oceânica vem ganhando cada vez mais notoriedade, tamanha a frequência da constatação de que muitas espécies aquáticas e regiões (até então preservadas) têm sido afetadas direta ou indiretamente por ações individuais e corporativas. Diante da lacuna existente nos registros relacionados à utilização de graxas em revestimentos instalados em poços de petróleo (tanto onshore quanto offshore), considerando as premissas da ecotoxicologia, este estudo destaca a fragilidade na divulgação dos parâmetros ambientais relacionados a algumas das graxas de estocagem (Kendex OCTG e Jet-LubeKorr-Guard) e descida (Lubrax Lith PM1 e Bestolife 72733) mais utilizadas no Brasil. Considerando a existência de opções que dispensam a utilização de tais produtos químicos durante todo o ciclo de vida dos produtos (tecnologia “dope-free”), o aprofundamento de estudos afins (especialmente testes de toxicidade), bem como a adoção de medidas com menor potencial poluidor nas atividades de construção de poços, são sugeridos.

Evaluation of the Elevated-Temperature Performance and Degradation Mechanisms of Thread Compounds

Summary Thread compounds play an important role in the sealing ability of casing connections in the oil and gas industry. Next to their lubricating role during assembly, most of these thread compounds make use of nonbiodegradable or persistent particle additives to aid in the sealing ability. Replacing these additives for biodegradable and nonpersistent alternatives is, however, a challenge in high–temperature (&amp;gt;150°C) well environments. This paper presents an investigation of the high–temperature failure mechanisms of thread compounds, with the aim of developing biodegradable high–temperature–resistant thread compounds. To this end, the performance of commercially available, environmentally acceptable thread compounds was investigated using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), high–temperature rheometry, and high–temperature pin–on–disk experiments. The compounds are assessed for their stability, consistency, lubricity, and the resulting wear at high temperature. The results indicated that, without exception, the commercially available thread compounds investigated in this study fail by adhesive and/or abrasive wear at approximately 150°C because of thermally induced degradation. To remedy this and to validate the found failure mechanisms, a prototype thread compound was developed. The conclusion was that a successful high–temperature–resistant environmentally acceptable thread compound can be developed using the methodology described. The key property of this thread compound is the ability to form a tribofilm during makeup that protects the surface at a later stage when the lubricant has lost its consistency and the base oil is fully evaporated.

On the Sealability of Metal-to-Metal Seals With Application to Premium Casing and Tubing Connections

Summary Metal–to–metal seals are used in connections of casing and tubing in oil and gas wells. This paper describes the mechanisms of sealing metal–to–metal seals as investigated using an experimental setup and a stochastic numerical sealing model. Experiments were conducted for a variety of thread compounds and applied pin/box surface coatings. The results were used to validate a stochastic numerical sealing model for sealability. The model couples a contact–mechanics model with a flow model and takes into account the influence of all the surface–topography features by introducing the concept of seal permeability. Once validated, the model was used together with the experimental results to better understand the sealing mechanisms of metal–to–metal seals. The sealing configuration is a face seal with an 80–mm roundoff radius on one face pressing against a flat on the other face. The face–seal specimens were manufactured from P110 tubing to ensure material properties that are representative for casing or tubing. The test setup used is designed for investigating only the metal–to–metal seal of the connection. The setup can perform rotary sliding under constant load to simulate surface changes during makeup and subsequently perform a leakage test. The sealing limit is determined by applying 700–bar fluid pressure and then gradually reducing the normal force until leakage is observed. The data are subsequently used to validate the previously published stochastic numerical sealing model. The results indicate a strong dependence on the type of thread compound used for the onset of leakage. The thread compound affects the amount of wear and thus changes the surface topography of the interacting surfaces. It is shown that the stochastic numerical sealing model is capable of predicting the onset of leakage within the experimental accuracy. The model shows further that certain surface topographical features improve the sealing performance. In particular, a surface manufactured by turning on a lathe that is in contact with, for instance, a smooth shot–blasted surface topography leads to highly localized contact areas, which in turn yield the best sealing performance.

Dry dope-free premium connections: a zero discharge technology validated through laboratory and field testing and usage

Dope-free alternatives to standard thread compounds used for casing and tubing connections became commercially available around 2003. The challenges from galling resistance needs and handling and storage requirements were addressed. The lessons learnt from the initial uses and experiences with the dope-free solution were incorporated into products that are reliable and have proven their suitability in environments that vary from the extremely humid and cold North and Barents Seas to the sandy and hot environment of the Middle East. The experiences to date not only confirm the validity of initial drivers —mainly related to the environmental care—for the development of these alternatives, but also open up the possibility of the complete elimination of thread compound from the casing and tubing installation and storage processes. The dope-free solution has demonstrated suitability for application in all tubing and casing dimensional size ranges including: all type of steels (such as common carbon steel—both API grades and proprietary), 13Cr, and corrosion resistance alloys (CRA), premium connections with metal-to-metal seal both threaded and coupled (T&amp;C), as well as integral connections. Experience with large outside diameter (OD) semi-premium connections indicates that this can be another area of application for dope-free solutions. This paper describes the different experiences related to the field use of dry, dope-free solutions, the improvements and adjustments incorporated after initial experiences and operators feedback and the verification activities in laboratory and especially in experimental rigs under actual field conditions. The intention of this presentation is to present the advantages and the value obtained through the use of this technology.

Overview: Wellbore Tubulars (May 2007)

In this corner last year, we explored our continually evolving understanding of tubular performance. At the 2006 SPE Annual Technical Conference and Exhibition and the 2007 SPE/IADC Drilling Conference, we again were presented with outstanding investigations on several fundamental issues such as buckling and fatigue. However, as you well know, we cannot just stop here. Fundamentals must evolve into technology and then be extrapolated to design, application, and eventually implementation in the field. This implementation must bring business value through additional access to resources, savings in time, or savings in money. Applications of technology also can evolve. For example, vacuum-insulated tubing initially was used for steam injection, and now also is used to manage hydrate formation and annular fluid expansion. Such evolution also is visible with solid expandable tubulars. This technology has been highlighted in this feature since 2000 with applications focusing on remediation (e.g., sealing off problem zones or repairing corroded intervals). However, increasingly during the past few years, solid-expandables technology has been integrated into the design process to eliminate casing strings and provide a larger wellbore cross-section for subsequent drilling and production. Connection technology continues to evolve and meet the increasing demands placed upon tubulars. Long, extended-reach wells pose numerous drilling challenges. To reach desired targets, drillpipe stability, torsional strength, and hydraulic performance are required. Implementation of appropriate connection designs can allow for larger, more-rigid drillpipe, alleviating additional hydraulic and downhole torque concerns. In an effort to reduce the environmental effect of thread compounds, connection manufacturers are working to meet regulatory requirements to reduce, and even eliminate, pipe-dope discharge. Through a fundamental understanding of thread-compound benefits (e.g., ease of makeup, galling avoidance), multiple technologies have been developed. In conjunction with achieving "zero discharge," these technologies can improve rig handling and running speeds by eliminating thread-compound application. Field deployment of technology is not limited to product installation, but includes implementation of design concepts and tools. With a thorough understanding of the risks, reliability-based design methodologies, or other design tools coupled with appropriate material selection and equipment, can reduce overall development costs by identifying alternatives to standard approaches. Wellbore Tubulars additional reading available at the SPE eLibrary: www.spe.org SPE 100628 "Improving Drilling Performance Using Advanced Drillpipe With Streamline Connections" by M.J. Jellison, SPE, Grant Prideco, et al. SPE 105855 "First Gas Field Developed Using Exclusively Dope-Free Casing and Tubing Connections—Statoil Snøhvit" by Gabriel Carcagno, SPE, Tenaris, et al. SPE 100386 "Failure Analysis of String Corrosion and Its Protection During Constructing and Operating Gas Storage Facility in Bedded Salt Deposit" by Yuan Guangjie, PetroChina, et al. SPE 104055 "Rigless Tubing Repair Using Permanent and Retrievable Patches at Prudhoe Bay, Alaska" by J.Y. Julian, SPE, BP plc, et al. SPE 102150 "Development and Commercial Deployment of an Expandable Monobore Liner Extension" by C.F. Stockmeyer, SPE, Baker Oil Tools, et al.

Effect of surface coating and tin plating on friction characteristics of P-110 tubing for different thread compounds

Design factor problems related to galling failure have become an increasing concern for deepwater offshore wells. This paper presents the results of an experimental study conducted to determine friction characteristics of P-110 tubing coated with manganese phosphate and plated with tin. Six repeated tests were run to investigate the effect of lubrication type on friction characteristics of P-110 tubing by using thread compounds of API modified Threadkote-706, Shell Type-3 and Graphite/PTFE at a rotational speed of 5 rpm. In each test the bearing load was increased monotonically to a maximum value of 625 kN. The results of this study clearly indicate the importance of tin-plating in reducing the coefficient of friction.

Rating Thread Compounds for Galling Resistance

Results are presented from an experimental study which demonstrates the feasibility of using an existing galling tester and test method as a screening device for evaluating thread compound additives for galling protection. The galling tester employs tubular pin and box specimen pairs fabricated from steel tubing used in the oil field. For the test thread compounds, four different additive packages were used, all with the same grease base of lithium stearate. For reference purposes, the lithium stearate grease base without any additives was tested as one of the thread compounds. The data obtained on contact stress at galling failure show that of the five thread compounds tested, the best galling protection is afforded by the API Modified thread compound, the industry standard for casing and tubing used by the oil industry. The other four compounds show lower galling failure contact stresses of varying degrees. Friction coefficient data obtained during the tests are also presented and discussed.

Testing Thread Compounds for Rotary-Shouldered Connections

Summary This paper describes development of and the procedures and equipment described in API RP 7A1, Recommended Practice for Testing of Thread Compounds for Rotary Shouldered Connections, published in 1991.

Thread Compounds + Environment = Change

Introduction Environmental awareness, concern, and regulation have affected virtually every industry in the last several years, and the oil patch is no exception. Changes in the methods required for storage, use, and disposal of materials ranging from pipe coatings to drilling muds have spawned a flood of new products that are more environmentally acceptable. These new products not only differ in composition but also can exhibit substantially different performance properties. The change in performance properties will require changes in operational practices that have been in place for decades. Nowhere is this more true than for thread compounds. Thread Compound Background Historically, compounds used for both drilling and production applications have consisted of a petroleum lubrication grease containing a substantial percentage of heavy metals (lead, copper, zinc, or a combination of the three).The metals are present in a finely divided form as a powder or flake and may make up as much as 60 wt % of the thread compound. These metals have been used since the early days of the industry because their unique material properties provide two main performance requirements of a thread compound:protection against metal/metal contact and galling at high connection bearing stresses andthe sealing of potential leak paths at high internal pressures. Lead, copper, and zinc are malleable and ductile. These properties allow them to compact and deform without fracturing, thereby forming an effective seal either in the thread form of the casing or tubing or between the shoulders of rotary connections. Their ability to prevent wear and damage of ferrous metal surfacesis evidenced by their wide use in a variety of bearing materials. Environmental Factors Unfortunately, restrictions on the use and disposal of materials containing heavy metals have and will continue to become increasingly severe. U.S. Environmental Protection Agency (EPA) guidelines for determining whether a waste material is hazardous include lead and several other heavy metals on the list of toxic substances. If the defined test procedure (the Toxicity Characteristic Leaching Procedure) indicates that any substance on the toxicity list is present in an extract solution above the stated limits. the material is considered a hazardous waste and must be disposed of according to the appropriate regulations. Zinc currently is not on the list but most likely will be added within the next year. Copper also is not listed and probably will not be for the near future. Both zinc and copper, however, are listed for a similar test procedure required by the State of California. Other areas of concern, besides disposal of waste material residues and contaminated containers, are not covered specifically by EPA regulations. Some examples are contaminated effluent from hydrostatic testers that may be discharged to a sanitary sewer system, rain-water run-off from pipe yards and threading facilities, and contaminated mud pits and surrounding soil in field operations. These situations are, for the most part, subject to state and local regulations that can vary considerably, depending on the location. State and federal regulations based on marine biotoxicity and other environmental-impact properties also restrict discharges from offshore operations. Clearly the composition of thread compounds must and will continue to change as environmental regulation increases and other substances are added to the toxicity lists. Performance Considerations What effect do the changes in thread compound composition have on performance properties and operational practices? The answer is complex. The compounds used for the past 40 or 50 years have been fairly generic with well-defined categories sharing similar performance properties. The tables of recommended torque values and operational practices that the API and pipe manufacturers publish are based on the use of these compounds. The new compounds that have appeared recently are of proprietary formulation and can vary widely in both composition and performance properties. Drilling Compounds. Nonmetal drilling compounds rely on such materials as graphite, nonheavy metal oxides or other solid lubricants, and extreme-pressure additives to provide protection against connection galling. Most nonmetallic solids, however, fracture under applied stresses and do not compact and deform into a continuous gasket-like seal between the shoulders as do powdered metals. Seal failure can result in connection damage from washout caused by high-solids drilling muds under pressures as high as 6,000 psi. Because of the malleability of the metal powder particles, high metal compounds also are more effective than nonmetallics at uniformly distributing bearing stresses (60,000 psi in drillcollars) around the connection shoulders. This is particularly critical if the shoulders are not exactly parallel because of wear or substandard field reworks. Uneven distribution of shoulder bearing stresses can cause pin fatigue failures and reduce drillstring life. JPT P. 614^