Life Extension of Ageing Offshore Structures: A Framework for Remaining Life Estimation

2017 ◽  
Author(s):  
Ashish Aeran ◽  
Sudath C. Siriwardane ◽  
Ove Mikkelsen ◽  
Ivar Langen
Keyword(s):  
Fatigue Damage ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Offshore Structures ◽  
Assessment Process ◽  
Localized Corrosion ◽  
Life Extension ◽  
Remaining Life ◽  
Structural Degradation ◽  
Life Estimation

The remaining life estimation of ageing structures has been identified as a growing challenge in the oil and gas industry. Although the available guidelines provide a general fatigue assessment process, it is necessary to have more detailed guidelines by adding relevant theories and models which can capture the time-dependent structural degradation more precisely. To address this, a new framework is proposed in this paper. The proposed framework provides recommendations on various issues such as simulation of structural degradation, loading history, effect of localized corrosion, selection of a suitable fatigue strength curve and fatigue damage theories. Recently developed precise fatigue damage theory is also included in the proposed framework.

scholarly journals ON STANDARDIZATION OF LABORATORY SOIL TESTING IN OFFSHORE GEOTECHNICAL SURVEY

Gruntovedenie ◽  
2021 ◽  
Vol 1 (16) ◽  
pp. 16-52
Author(s):  
E.A. Voznesensky ◽  
◽  
A.S. Loktev ◽  
M.S. Nikitin ◽  
◽  
...  
Keyword(s):  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Offshore Structures ◽  
Soil Testing ◽  
National Standard ◽  
Gas Industry ◽  
Code Of Practice ◽  
Complete Section ◽  
Testing Practice ◽  
Russian Soil

Issues of laboratory soil studies standardization in offshore geotechnical survey are discussed in connection with the end of expertise of two new regulative documents – new edition of the Code of practice and Russian national standard developed on the basis of international ISO standard. Since these documents of different level belong also to different categories (geotechnical survey and oil and gas industry), the authors analyze their interrelation and consistency, from one hand, and the preparedness of Russian soil testing practice to implementation of the new standard which results from harmonization with international ones, from the other. Complete section of the standard draft related to soil laboratory testing is presented, preceded by commentary on some important issues regarding the implementation of its specific methodic statements. It is concluded that the new national GOST draft «Petroleum and natural gas industries. Specific requirements for offshore structures. Marine soil investigations» developed on ISO basis will be a useful document supported in general by Russian normative base but expanding a possible range of voluntary methods into well time-tested foreign approaches. This documents can be considered to be a toolkit annex to the Code of practice describing testing approaches beyond the scope of typical tasks

STUDY OF CHEMICAL REAGENTS AGAINST CORROSION PROCESSES IN THE CONDITIONS OF THE UZEN FIELD

2021 ◽  
Vol 73 (1) ◽  
pp. 185-195
Author(s):  
U. Zh. Tazhenbayeva ◽  
◽  
Ye.O. Ayapbergenov ◽  
G. Zh. Yeligbayeva ◽  
◽  
...  
Keyword(s):  
Corrosion Inhibitors ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Freezing Temperature ◽  
Gas Production ◽  
Localized Corrosion ◽  
Laboratory Research ◽  
Oil And Gas Production ◽  
Field Equipment ◽  
Long Run

One of the biggest challenges in oil and gas production projects is dealing with the various types of corrosion to which certain parts of field equipment are exposed. Selecting the right corrosion inhibitor for the specific environment is extremely important. Choosing inhibitors for a particular location can be a difficult task because there are many factors to be considered. Understanding the corrosion problems that can arise is important in the oil and gas industry, and knowledge of which inhibitors to use to deal with general and localized corrosion will save time and money in the long run. This article presents the results of studies of various brands of domestic and foreign corrosion inhibitors for use in the Uzen field: physical and chemical characteristics (density, viscosity, freezing temperature, mass fraction of active substance, compatibility with field waters, amine number), efficiency of corrosion inhibitors in laboratory conditions and on a bench simulating field reservoir conditions, taking into account pressure, temperature, fluid flow rate, as well as aggressive components - hydrogen sulfide and carbon dioxide. In addition, studies of corrosion inhibitors' effect on the process of preparation of production are also given. The works were carried out in the center of scientific and laboratory research of KMG Engineering branch " KazNIPImunaygas" LLP.

Structural Impact in FPSO Life Extension: A Class Perspective

2013 ◽  
Author(s):  
Christiane L. Machado ◽  
Sudheer Chand
Keyword(s):  
Service Life ◽  
Oil And Gas ◽  
Structural Response ◽  
Oil And Gas Industry ◽  
Environmental Data ◽  
Life Extension ◽  
Element Analysis ◽  
Actual Performance ◽  
Remaining Service Life ◽  
The Impact

The Offshore Oil and Gas Industry has converted a large number of units from trading tankers and carriers into Floating Production, Storage and Offloading units (FPSOs). Several of these have been moored offshore Brazil during the last 15 years. Following the discovery of offshore pre-salt fields some years ago, demand for FPSOs has increased, and the forecasts for productive field lives have grown. The result of these developments is the need to extend the service lives of existing FPSOs. The main aim of this study is to investigate FPSO structural response to environmental conditions and functional loads, considering the actual available tools for numerical simulations and Rule requirements, which currently are basic requirements for design review for Classification. The procedure was developed from one selected FPSO converted from a trading Very Large Crude Carrier (VLCC) tanker approximately 15 years ago and includes investigation of the impact on hull behavior comparing the motion analyses of the production unit under environmental data and software capabilities available at the period of conversion and actual performance: variances in the environmental (sea scatter diagrams) datasets; updates to Classification requirements for defining offloading conditions, environmental loads, acceptance criteria and remaining fatigue life (RFL); and incorporating the most recent gauged thickness for primary structure. The selected FPSO was evaluated according to prescriptive Rule requirements and also using finite element analysis, taking into account the previous conditions of Classification approval as well as the actual requirements and available data. Structural analysis included one global model and some local refined models to address strength, buckling and fatigue capacity of the typical portions/connections of the hull. The comparisons performed from the results of these analyses are a crucial step toward understanding the structural capacity of the FPSO at the conversion stage, its performance during the last 15 years, and its remaining service life. Differences were tabulated and evaluated so that a more precise level of uncertainty could be achieved for predicting the estimated remaining service life, and consequently, a new and dedicated approach to investigate the existing FPSO fleet is being generated.

ENVIRONMENTAL RISK MANAGEMENT: A PROPOSED SCHEME

1997 ◽  
Vol 37 (1) ◽  
pp. 714
Author(s):  
H.B. Goff ◽  
R.K. Steedman
Keyword(s):  
Risk Assessment ◽  
Risk Management ◽  
Environmental Risk ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Transport Processes ◽  
Assessment Process ◽  
Gas Industry ◽  
Environmental Risk Management ◽  
The Impact

Environmental risk assessment is becoming an increasingly important factor in the assessment process for new projects. The oil and gas industry is familiar with assessing and managing risks from a wide range of sources. In particular, risk assessment and management is fundamental to the evaluation and implementation of Safety cases. Risk assessment is essential in valuing exploration acreage. Various industry and government risk management standards and criteria have been developed for public and occupational health and safety.This paper examines the extension of these approaches to environmental risk management for the offshore oil and gas industry and proposes a conceptual management scheme.We regard risk as the probability of an event occurring and the consequences of that event. The risk is classified into four categories, namely:primary risk, which relates to the mechanical oilfield equipment;secondary risk, which relates to the natural transport processes. For example dispersion of oil in the water column and surrounding sea;the tertiary risk, which relates to the impact on some defined part of the physical, biological or social environment; andthe quaternary risk, which relates to the recovery of the environment from any impact.Generally the methods of quantitatively analysing primary and secondary risks are well known, while there remains considerable uncertainty surrounding the tertiary and quaternary risk and they are at best qualitative only. An example of the method is applied to coral reef and other sensitive areas which may be at risk from oil spills.This risk management scheme should assist both operators and regulators in considering complex environmental problems which have an inherent uncertainty. It also proves a systematic approach on which sound environmental decisions can be taken and further research and analysis based. Perceived risk is recognised, but the management of this particular issue is not dealt with.

Stress Concentration Factors Calculation: Analytical and Numerical Approaches for Welded Tubular Joints

2020 ◽  
Author(s):  
Nathalia Paruolo ◽  
Thalita Mello ◽  
Paula Teixeira ◽  
Marco Pérez
Keyword(s):  
Stress Concentration ◽  
Oil And Gas ◽  
Hot Spot ◽  
Experimental Tests ◽  
Oil And Gas Industry ◽  
Offshore Structures ◽  
Gas Industry ◽  
Tubular Joints ◽  
Concentration Factors ◽  
Stress Concentration Factors

Abstract In the oil and gas industry, fixed platforms are commonly applied in shallow water production. In-place environmental conditions generates cyclic loads on the structure that might lead to structural degradation due to fatigue damage. Fatigue is one of the most common failure modes of offshore structures and is typically estimated when dimensioning of the structure during design phase. However, in times when life extension of existing offshore structures is being a topic in high demand by industry, mature fields may represent an interesting investment, especially for small companies. Concerning fixed platforms, composed mainly by welded tubular joints, the assessment of hot spot stresses is considered to predict structure fatigue. The estimation of welded joint hot spot stresses is based on the stress concentration factors (SCFs), which are given by parametric formulae, finite element analysis (FEA) or experimental tests. Parametric formulae may be defined as a fast and low-cost method, meanwhile finite elements analysis may be time consuming and experimental tests associated with higher costs. Given these different characteristics, each method is applied according to the study case, which will rely on the joint geometry and associated loads. Considering simple joint geometries several sets of parametric equations found in the literature may be applied. On the other hand, the SCFs calculation of non-studied yet complex joints consider known formulae adapted according to the under load joint behavior and geometry. Previous analysis shows that this adaptation may furnish different results compared to those obtained by FEA. Furthermore, it is observed that even for simple joints the results derived from the different methods may differ. Given their importance for the oil and gas industry, since they are the basis for the assessment of the fatigue life of welded tubular joints which may impact on additional costs related to maintenance and inspection campaigns, the estimation of SCFs must be the most accurate as possible. Therefore, this paper intends to investigate the differences between results derived from parametric formulae and different FEA studies.

An Oil Field Structural Integrity Assessment for Re-Qualification and Life Extension

2013 ◽  
Author(s):  
Abe Nezamian ◽  
Joshua Altmann
Keyword(s):  
Weight Control ◽  
Structural Integrity ◽  
Offshore Structures ◽  
Oil Field ◽  
Assessment Process ◽  
Performance Criteria ◽  
Life Extension ◽  
Original Design ◽  
Integrity Assessment ◽  
Design Life

The ageing of offshore infrastructure presents a constant and growing challenge for operators. Ageing is characterised by deterioration, change in operational conditions or accidental damages which, in the severe operational environment offshore, can be significant with serious consequences for installation integrity if not managed adequately and efficiently. An oil field consisting of twelve well head platforms, a living quarter platform (XQ), a flare platform (XFP) and a processing platform (XPA) are the focus of this paper, providing an overview of the integrity assessment process. In order to ensure technical and operational integrity of these ageing facilities, the fitness for service of these offshore structures needs to be maintained. Assessments of the structural integrity of thirteen identified platforms under existing conditions were undertaken as these platforms are either nearing the end of their design life or have exceeded more than 50% of their design life. Information on history, characteristic data, condition data and inspection results were collected to assess the current state and to predict the future state of the facility for possible life extension. The information included but was not limited to as built data, brown fields modifications, additional risers and clamp-on conductors and incorporation of subsea and topside inspection findings. In-service integrity assessments, pushover analyses, corrosion control and cathodic protection assessments and weight control reports were completed to evaluate the integrity of these facilities for requalification to 2019 and life extension to 2030. The analytical models and calculations were updated based on the most recent inspection results and weight control reports. A requalification and life extension report was prepared for each platform to outline the performance criteria acceptance to achieve requalification until 2019 and life extension until 2030. This paper documents the methodology to assess the platform structural integrity in order to evaluate platform integrity for the remaining and extended design life. An overview of various aspects of ageing related to these offshore facilities, representing risk to the integrity, the required procedures and re assessment criteria for deciding on life extension of these facilities is presented. This paper also provides an overall view of the structural requirements, justifications and calibrations of the original design for the life extension to maintain the safety level by means of maintenance and inspection programs balancing the ageing mechanisms and improving the reliability of assessment results.

Remaining life estimation by fatigue damage sensor

2010 ◽  
Vol 163 (1) ◽  
pp. 3-11 ◽  
Author(s):  
K. Nihei ◽  
O. Muragishi ◽  
T. Kobayashi ◽  
K. Ohgaki ◽  
A. Umeda
Keyword(s):  
Fatigue Damage ◽  
Remaining Life ◽  
Life Estimation

scholarly journals Comparative Study of Structural Reliability Assessment Methods for Fixed Offshore Structures

2021 ◽  
Author(s):  
E. Mat Soom ◽  
M.K. Abu Husain ◽  
N.I. Mohd Zaki ◽  
N.A. Mukhlas ◽  
S.Z.A. Syed Ahmad ◽  
...  
Keyword(s):  
Structural Reliability ◽  
Oil And Gas ◽  
Offshore Structures ◽  
Mitigation Strategies ◽  
Life Extension ◽  
Risk Level ◽  
Long Distance ◽  
Design Assessment ◽  
Integrity Assessment ◽  
Structural Deterioration

The oil and gas sector has recognised structural integrity assessment of ageing platform for prospective life extension as a rising concern, particularly in encountering the randomness of the harsh ocean environments. This condition leads to uncertainty in wave-in-deck load estimates and a high load level being imposed on offshore structures. This emphasises the necessity of enhanced reliability, as failure might result in inaccessibility because of the uncertainties related to long-distance services, such as accuracy of predictions of loads and responses. Even though the established guidelines present a fundamental assessment, additionally, comprehensive rules are required. This paper performed a reliability analysis incorporating practical approaches that can more accurately represent time-dependent structural deterioration. The following two procedures have been adopted by a majority of significant oil and gas operators to monitor the safety and integrity of these structures: a) Ultimate Strength Assessment (USA) method and b) Reliability Design Assessment (ReDA) method. A comparison of these two reliability approaches was performed on selected ageing jacket structures in the region of the Malaysian sea. The comparative findings, namely, reserve strength ratio (RSR) at various years of the return period (RP) and ratio value for risk of failure regarding the probability of failure (POF), provided a check and balance in strengthening confidence in the results. The findings showed that the structural components might safely survive either using the USA and ReDA method in such conditions, as the reliability indexes were determined to be satisfactory compared to allowable values from ISO 19902 design specifications. Therefore, these evaluations were determined to control the risk level of the structure during the remaining of its lifetime and undertake cost-effective inspections or mitigation strategies when necessary.

Innovative Approach to Analysis Drilling Tool Works

2021 ◽  
Author(s):  
Ramil Ilshatovich Gubaidullin
Keyword(s):  
Fatigue Damage ◽  
Information Technologies ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
The Body ◽  
Fatigue Wear ◽  
Drilling Tool ◽  
Full Life Cycle ◽  
Drill Pipes ◽  
Variable Stresses

Abstract Information technologies have long been an integral part of our lives, and the oil and gas industry has also undergone natural IT evolution. Modern technologies have allowed to automate the basic processes and structure the existing order of work, but there are still unresolved problems, one of which is monitoring the full life cycle of drill pipes and predicting the accumulation of fatigue damage. In most cases, the failure of the drill pipes is associated with fatigue destruction, which begins with microcracks as a result of exposure to variable stresses during the construction of the well (drilling). Currently, there are no effective methods to control accumulated fatigue damage or residual durability of the pipe at a given level of stress. In this regard, a system is required for a more reliable assessment of the condition of the drill pipes, which will take into account the whole list of factors influencing the rate of accumulation of fatigue damage in the body of the pipe and will allow to calculate (predict) the accumulated fatigue of the drilling pipes, using data from drilling regimes and well parameters. Understanding the mechanism of accumulation of fatigue wear, which leads to the failure of drilling pipes, makes it possible to manage this process, significantly reduce the cost of maintenance of the drilling pipe fund and reduce incidents with drilling pipes.

Rationale for load specifications and load factors in the new CSA code for fixed offshore structures

1991 ◽  
Vol 18 (3) ◽  
pp. 454-464 ◽  
Author(s):  
Ian J. Jordaan ◽  
Marc A. Maes
Keyword(s):  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Offshore Structures ◽  
Limit States ◽  
Gas Industry ◽  
Offshore Installations ◽  
Load Factors ◽  
Annual Probability ◽  
Acceptable Risks ◽  
Economic Analyses

The Canadian Standards Association (CSA) initiated effort in 1984 aimed at the development of an offshore code for production structures in the oil and gas industry. The present paper summarizes the rationale behind the development of design load specifications in the preliminary standard S.471 "General requirements, design criteria, the environment, and loads." As part of this development, background calibration studies were conducted in tandem with the work of various committees. Selected results from these studies are also discussed in this paper. The basic objectives and tools for developing load criteria for the design of offshore installations are discussed. The use of economic analyses of cost versus safety of structures does not provide clear guidance, and the perspective taken is that of acceptable risks to an individual. This is used in the context of limit states design, which, in S.471, incorporates two safety classes. In order to provide consistent safety levels, the environmental loads are divided into categories based on frequent and rare occurrence, examples being waves and earthquakes, respectively. The role of the annual probability of failure in setting target levels of reliability as well as in the calibration process is emphasized. Various aspects of calibration are summarized, including the background to the rare-frequent separation of loads, the objective function used to optimize the results, as well as the method of handling model uncertainty. Key words: environment, limit states, loads, offshore, reliability, resistance, safety, structures.

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