Blowout Preventer Research Articles

Research on the Risk of Drilling Phases Based on the Development Model of Shallow-Water Subsea Trees

China is actively advancing offshore oil and gas exploration and development, focusing on addressing the technical challenges associated with resource extraction in shallow waters. The shallow-water subsea tree development model has gradually been applied in such environments, alleviating some construction difficulties. However, it still poses well control risks that require systematic analysis and quantitative evaluation. Given that the blowout preventer (BOP) is located on the platform and the shallow-water subsea tree is only used during certain drilling stages, this study divided the drilling process into two phases: the first three sections and the fourth section. Based on the “man–machine–material–environment” analytical framework and an improved system-theoretic process analysis (STPA), a control model for the construction phases was developed. Fault tree analysis (FTA) was then employed to identify comprehensively the potential risks from the platform to the wellbore in both phases. Subsequently, the decision-making trial and evaluation laboratory (DEMATEL) method were used to assess quantitatively the well control risks. Using the average weight as the evaluation criterion, high-risk factors exceeding the average weight in each phase were identified. The results indicate that in the shallow-water subsea tree development model, well control risks in the first three drilling sections primarily stem from human errors and equipment failures, while risks in the fourth section are mainly caused by damage to the subsea tree itself. The identified risk factors provide a theoretical basis for enhancing well control safety management in the shallow-water subsea tree development model.

Comments: Celebrating a Legacy: 100 Years of Innovation and 75 Years of JPT at the 2024 ATCE

_ Are you ready to join us for SPE’s Annual Technical Conference and Exhibition (ATCE) in New Orleans, 23–25 September? As SPE celebrates a century of innovation at the 2024 ATCE, we also mark the 75th anniversary of the Journal of Petroleum Technology (JPT). These twin milestones stand as a testament to the achievements that have driven our field forward—innovation, pushing boundaries, setting new standards, and fueling the energy that powers the world. Through the highs of technological breakthroughs and the lows of economic challenges, the oil and gas industry—and ATCE and JPT—have continually evolved, proving their resilience and adaptability. When considering the innovations in our industry, key advancements that often stand out include hydraulic fracturing, horizontal drilling, deepwater exploration, enhanced oil recovery, digitalization and automation, LNG technology, FPSOs, subsea systems, and decarbonization and emissions mitigation. However, the incremental steps that collectively contributed to the broadly defined “wow” factors above are equally notable. To mention only a sampling: enhanced drill-bit designs, advancements in onshore and offshore drilling rigs, real-time data collection, development of 4D seismic technology, integration of multiple data types (e.g., seismic, well logs, production data) for more-comprehensive reservoir characterization, materials-science advancements (polymers, nanocoatings), development of blowout preventers, improved leak-detection systems, and advancements in produced-water treatment and recycling technologies. Less often recognized are the failures that were essential prerequisites for eventual success. The "fail fast, fail often" approach allowed for rapid feedback and necessary adjustments, though it also contributed to the downfall of some startups over the years. As individuals, embracing failure and viewing it as a stepping stone to success is not always our natural response. Presentations at industry events on "lessons learned" vary in transparency, often influenced by differing definitions of failure, stakeholder sensitivities, and legal considerations. As a result, many of the hard knocks that paved the way for the industry's "wow" factors remain largely unknown. ATCE’s theme, “Powering the Future of Energy with a Century of Innovation,” honors the legacy of past breakthroughs while celebrating their ongoing role in shaping a resilient and sustainable future. Olivier Houzé will be named 2025 SPE President with the official passing of the baton from 2024 President Terry Palisch at ATCE. In this issue of JPT, Houzé shares his insights on the challenges facing our Society and its members in his inaugural vodcast and column, “A Roadmap for a Very Busy Year.” Visit the SPE Pavilion (Booth 1449) in the exhibition hall for a variety of SPE Pavilion Talks, including the JPT editors on Tuesday, 24 September, at 1:30 p.m. We’ll highlight the milestones of JPT’s coverage over 75 years and their significance for the future. Visit JPT to learn more about our commemorative features written to date about topics ranging from the Kurdistan Region of Iraq, Azerbaijan, the HSE journey, data science, artificial lift, and a closer look at the past 25 years of innovations in fracturing, drilling, and reservoir engineering. New This Year at ATCE - Strategic Panels will offer a platform for panelists to discuss the current and future challenges and opportunities facing the energy industry. - As an SPE member, you get a complimentary pass to the exhibition hall. If you are not a member yet, you can join now. This pass does not include access to the technical program or conference proceedings. Learn more about the free access pass here. - Non-members registered at the full conference rate will receive a post-show email with a complimentary 1-year SPE membership offer. This offer is valid for new members only, and individuals must meet membership qualifications to join. Whether you’re a seasoned professional or new to the field, ATCE offers an opportunity to connect, learn, and share. Here's to a century of ingenuity and three-quarters of a century of chronicling the journey!

Analysis of sealing performance of the rotary blowout preventer rubber ring in ultra deep wells

Analysis of sealing performance of the rotary blowout preventer rubber ring in ultra deep wells

What You Don’t Know About Chevron’s New 20K Anchor Project

_ After overcoming the impacts of the COVID-19 pandemic and closing significant technology and regulatory gaps, Chevron’s $5.7 billion Anchor project in the US Gulf of Mexico (GOM) is nearly ready to start producing oil. When it finally does, it will mark the start of the “20K” era for the deepwater oil and gas industry. The term 20K refers to the project’s core technologies, designed to handle wellhead pressures of up to 20,000 psi—a first for the subsea market. The advancement opens the door to previously inaccessible reservoirs by stretching the boundary of deepwater technology beyond the technical limit of 15,000 psi established in the past decade. In particular, the drive to reach such extremes is a response to the demands posed by the Lower Tertiary Wilcox play which Chevron pioneered the development of in 2014 with its Jack/St. Malo project. Output from the high-pressure, low-permeability, and ultradeep formation is expected to rise from last year’s 270,000 B/D to around 750,000 B/D by 2028. This would represent a shift from 13% to nearly 40% of the US GOM’s total of roughly 2 million B/D, according to Enverus Intelligence Research. The success of just a handful of projects like Anchor is crucial for achieving these projections. Located approximately 140 miles offshore Louisiana in about 5,000 ft of water, Chevron holds a 62.8% share in the project, with TotalEnergies owning the remaining interest. The initial phase includes seven wells targeting reservoir depths between 30,000 and 34,000 ft. Chevron has drilled three so far. Anchor’s semisubmersible floating production unit (FPU) arrived in the GOM last year after its hull was built in South Korea and topsides integrated along the Texas coast. The FPU has nameplate capacity of 75,000 B/D but upon delivery, Chevron determined it could make small modifications to boost the facility’s peak throughput to 86,000 B/D—an almost 15% increase. At this year’s Offshore Technology Conference (OTC) in Houston, Chevron’s Anchor project team offered a behind-the-scenes look at their journey to the precipice of first oil. Drawing from several papers they presented, here are some of Anchor’s biggest challenges and achievements. A Project of Firsts The nature of the Anchor project is such that it involves a number of industry firsts and records. At the top of that list is Transocean’s Deepwater Titan drillship which Chevron inked a 5-year $830 million contract for while it was still under construction in 2018. The rig began operations in the GOM in June 2023 as the second eighth-generation drillship ever built but holds claim to being the first ever rated for 20K operations. Originally planned to be a 15K-rated vessel, the Deepwater Titan was upgraded on Chevron’s request to host two NOV-supplied 20,000-psi blowout preventers (BOPs). Combined with the lower marine riser package, the BOP stack weighs in at more than 1.1 million lbs. Chevron points out in OTC 35148 that the BOPs were not needed to drill the wells—for that, 15,000-psi BOPs would have sufficed—but they were required for well control during the completion phase when hydrocarbons are most likely to flow to surface.

Influence of modelling methods of a lower marine riser package on dynamics of risers in hang-off mode

The paper presents the modelling of risers dynamics by means of the 3D formulation of the lumped mass method (LMM). The lower marine riser package (LMRP) and blowout preventer (BOP) are essential parts of the riser, which in the case hang-off conditions can affect the behavior of the riser. The paper presents three different approaches to modelling the LMRP/BOP. The LMRP/BOP is treated either as a lumped mass, or as a rigid body with five degrees of freedom, or it is discretized together with a riser by means of the LMM. The comparison of the different models is carried out for free vibrations and the results are compared with the results presented in the literature by other researchers. The influence of the models of the LMRP/BOP on riser motion in its transport to a new position is analyzed. The nonlinear model of riser dynamics takes into account large deformations and the influence of the marine environment. Results of numerical simulations confirm the assumption that it is possible to model the LMRP/BOP as a rigid body with five degrees of freedom, which eliminates the necessity of discretizing the LMRP/BOP by means of the finite element method or the lumped mass method.

Dynamic calculation of stress influence law of rubber core sealing surface of the rotating blowout preventer with defects

The bubble and crack defects in the production and operation of the rubber core of the rotating blowout preventer (RBOP) easily cause fatigue failure, leading to well-controlled severe accidents. Based on Yeoh’s principal structure equation, the dynamic sealing model of rubber core was established in this paper. The sealing process of the rubber core in lifting and drilling was calculated and analyzed. The stress influence law of typical cracks and bubble defects that affect the fatigue failure of rubber core sealing surface was analyzed. The results are as follows: (1) When the drill pipe joint passes through the RBOP, the structure of the rubber core is significantly deformed. This stage may cause damage and failure of the rubber core. (2) The cracks and bubble defects lead to a decrease in the stability of the sealing surface. With the increase of stress at the defect, the crack of the rubber core is easy to expand. (3) In the same location of the rubber core defects, cracks compared to bubble defects have a more significant impact. For the same type of crack, the bottom left side (A1) and the outer surface underside (D1) crack reduce the stress at the position of the rubber core sealing surface to the maximum. The research results provide a reference basis for defect detection, sealing performance, and service life of rubber cores, in order to improve the reliability evaluation standards of blowout preventer rubber cores, improve well control safety, reduce the occurrence of safety accidents, and improve operational efficiency.

Endovascular Stenting for Prevention of Arterial Blowout in Patients with Advanced Vulvar Cancer

Endovascular Stenting for Prevention of Arterial Blowout in Patients with Advanced Vulvar Cancer

ANALYSIS OF STRUCTURAL CHARACTERISTICS OF FIXING OF PREVENTOR VALVES

The article analyzes the conditions of the stress-strain state in which blowout preventers operate. The dependences for the strength calculation of fixing blowout preventers are given. The advantages and disadvanges of various designs of fastening devices and seals of fasteners are identified. Also, the issues of testing, repairing and operating blowout preventers are considered. Key words: blowout preventers, smooth fit, connection, mechanical stresses, stress-strain.

Study on the Shearing Force of Ram and Fracture Characteristics of Drillpipe Under Precutting

Summary The working pressure of the hydraulic system, as well as the volume and weight of the ram blowout preventer (BOP), cannot be increased excessively. This limitation affects the shearing force provided by the hydraulic cylinder of the BOP. When shearing high-strength, large-thickness, and large-diameter drillpipes, it is easy to cause shear failure, making blowout control challenging. Therefore, we proposed a high-pressure water-jet-assisted precutting method to reduce the force required to shear the drillpipe. Based on the numerical model verified by experiments, we compared and analyzed the shearing force variations and drillpipe fracture characteristics under different precutting methods. We also provided recommendations for selecting precutting methods. Furthermore, we identified the weights and grades of drillpipes that affect the shearing force under precutting. The results demonstrate that precutting the drillpipe can reduce shear forces, shorten fracture time, and improve fracture quality. The use of water-jet precutting technology enhances the efficiency of emergency well shut-in operations and subsequent pipe fishing. The presented technology is currently at a prefeasibility stage, and further efforts are needed to implement these ideas in practice.

Data Analytics for Decision-Making in Evaluating the Top-Performing Product and Developing Sales Forecasting Model in an Oil Service Company

This study addresses the strategic challenges faced by a company specialising in the manufacture of oil and gas equipment. Following organisational restructuring, which involved the dissolution of one business unit and the creation of another, the company is navigating complexities in product focus and manpower allocation within the Asia-Pacific region. The research problem centres on identifying the top-performing product, determining potential countries for establishing a support base facility based on sales performance, and developing a method for forecasting future sales. The research involved retrieving and pre-processing historical sales data, then performing a thorough descriptive and predictive analysis. The data was partitioned into training and testing sets to facilitate predictive analytics. Several predictive models were developed and tested, including neural networks, linear regression, gradient-boosted trees, random forests, and ARIMA methods. Tableau Public was utilised for descriptive analytics, whereas RapidMiner Studio was employed for predictive analytics. The study’s results, derived through both descriptive and predictive analytic methods, reveal critical insights. The Blowout Preventer (BOP) emerged as the top-performing product in the Asia-Pacific region. In terms of establishing support base facilities, Malaysia was identified as the ideal location for the BOP, while Indonesia was found suitable for the Manifold product group. Furthermore, the Random Forest model was determined to be the most effective for forecasting future sales. These findings provide strategic guidance for the company in product focus, regional expansion, and resource allocation, contributing significantly to the company’s decision-making process in a competitive industry.

Application of Mode Superposition Method in the Recoil Response of Deepwater Drilling Risers after Emergency Disconnection

Summary How to effectively control the recoil response after an emergency disconnection is one of the core technical problems in ensuring the safe and reliable operation of a deepwater drilling riser. Currently, the theoretical analysis is based on a discretization model or numerical simulation, which ignores the continuity of the riser system and the coupling effects of load acting on the riser. To address this problem further, in this paper, we establish a mechanical model and control equation with infinite degree of freedom for riser recoil response, where the heave motion of the floating drilling platform, seawater damping, and the viscous resistance of drilling fluid discharge were taken into account. In addition, the correctness of the model and solving approach are verified against the Orcaflex software. On this basis, the influence of wave period, wave height, initial phase angle, and tension coefficient on the recoil characteristics are discussed. The success of riser emergency disconnection is related to the clearance between the lower marine riser package (LMRP) and the blowout preventer (BOP) and the axial force distribution of the riser. The influence of the above-mentioned factors on the riser recoil response is also complicated. On the basis of the assumptions put forward and the model established, some quantitative conclusions are drawn. This study is of reference significance for safety control of riser emergency disconnection operation.

Three-model-driven fault diagnosis method for complex hydraulic control system: Subsea blowout preventer system as a case study

Hydraulic control is a control pattern that uses compression fluid as the energy medium and information medium. Hydraulic system is widely used in the control of industrial systems because of its flexibility and reliability. Hydraulic systems have the characteristics of strong fault concealment, significant sensor delay, and a complex signal transmission mechanism. Hence, it is very difficult to identify the faults of systems under the influence of powerful nonlinear time-varying characteristic. The diagnosis of complex hydraulic control system is a problem facing the current research. In order to cope with the challenges caused by limited sensors and concealment of faults, a three-model-driven fault diagnosis method is proposed for complex hydraulic control system. The three hydraulic control system models with regard to energy, fluid and information are proposed and established to explain the work process of the system from different perspectives. The diagnostic model is completed by establishing a fault reasoning model based on the Bayesian network. A redundant control system for subsea blowout preventer is used as a case to demonstrate the proposed method, and the results show that the proposed method has high accuracy.

Optimum and efficient design of steel foot over bridges

This work used the Finite Element Method (FEM) to estimate the shear force for a blind shear ram type blowout preventer. In recent years, significant advancements have been made in the design of Foot Over Bridges (FOBs) through the utilization of advanced analytical methods, innovative materials, and novel bridge concepts. FOBs have gained popularity in urban India due to their ability to facilitate safe pedestrian crossings without disrupting vehicular traffic flow, thereby enhancing pedestrian safety in areas with heavy traffic. This research focuses on the development of an economically optimized steel FOB design specifically tailored for the Mumbai region. The primary objectives are to ensure durability, stability, safety, and cost-effectiveness in the design. The study involves modelling the typical span of a skywalk structure using STAAD Pro, followed by comprehensive analysis and design iterations for various configurations based on real-world spans of existing pedestrian bridges. Static loading conditions are applied to the FOB models, allowing important characteristics like weight, number of joints, number of members, weld lengths, painting surface area, and natural frequency of pedestrian bridges to be evaluated. These factors are carefully contrasted to determine the bridge design that is the most economical. Additionally, vibration tests are conducted on two selected skywalks to assess their compliance with serviceability criteria. The research scrutinizes the utilization ratio of members in the bridge structures and explores variations in section sizes within the design to achieve the optimal configuration. The findings are presented in detail, offering valuable insights into the process of identifying the most economical FOB design from the skywalks in the Mumbai suburban region. This study contributes to the enhancement of pedestrian infrastructure in urban India by delivering a robust and cost-efficient FOB design approach.

Calculation method of deep-water surface conductor bearing capacity based on jetting operation parameters

The surface conductor bears the weight of the Christmas tree, a blowout preventer (BOP), and casings from various layers, and is subject to immense force. It is also affected by the coupling effect of the drilling platform and wellhead load for a long time. The accurate characterization of its bearing capacity is an important guarantee for the safety of deepwater drilling operations. Through the analysis of the installation process, mechanical characteristics, and the theoretical bearing capacity model of the surface conductor, three important stages of jet drilling, lifting up jet string, and running jet string are selected. Carry out the jet operation parameters and vertical force analysis for each stage, reveal the relationship between jet operation parameters and vertical friction of the surface conductor, and establish the real-time bearing capacity calculation model of the surface conductor of each stage. From the operation efficiency and economy, an analysis method of bearing capacity based on an actively pressing downward experiment is established when the well is located in a new block or a shallow block with complex geology. The coefficient of each model is corrected by the known well data, and the adaptability of the bearing capacity checking methods in different stages is evaluated. The results show that the calculation accuracy of the surface conductor bearing capacity model based on jetting operation parameters is more than 85%, and the error is reduced by 20% compared with the conventional model. The calculation accuracy is higher when the calculation is based on the upper friction parameter or lower friction parameter. The calculation method of deep-water surface conductor bearing capacity based on jetting operation parameters has been successfully applied in most deep wells in the South China Sea in recent two years and has become an important method for deep-water surface conductor design, which ensures the stability of the wellhead of deep-water oil and gas wells.

High-temperature sealing performance and structure optimization of rubber core for conical blowout preventer

Conical blowout preventer is a vital sealing component in the process of petroleum and gas development, if it were to malfunction, which will result in extremely severe consequences. In order to investigate sealing performance of conical blowout preventer at high temperature and reduce failure rate of rubber core. Firstly, high-temperature tensile and compression experiments for the rubber were conducted, then the constitutive model parameters for rubber core material was confirmed. A numerical model for wellhead sealing of conical blowout preventer was established. Stress distribution and sealing performance of rubber core at different temperatures were investigated. Finally, structural optimization was performed of rubber core, support rib and piston. The results show that the lower end of rubber core is the primary sealing area. Stress concentration on rubber core and significant deformations are the primary reasons for the cracking and detachment of rubber core. As the temperature increases, sealing performance of rubber core gradually decreases. After optimizing structures of rubber core, support ribs and piston, sealing performance of rubber core has been improved. Those results hold significant importance in improving sealing performance of conical blowout preventer and ensuring the safety of operational processes, providing theoretical guidance for the optimization of blowout preventer structures.

Sealing performance and failure mechanism of rubber core for conical blowout preventer during the well shut-in process

Blowout preventer reliability is important for safe drilling operation. In order to study the sealing mechanism and failure mechanism of conical blowout preventer, a numerical model of conical blowout preventer was established based on the theory of large deformation of rubber, and the deformation law, stress distribution and sealing performance of rubber core in well shut-in operation were studied. The results show that there are stress concentrations in the contact area between the rubber core and the piston, the grooves in the middle of the adjacent support ribs, and the chamfered corner of the inner wall of the rubber core, the main form of failure at these locations is rubber cracking. Higher stress is present in the neck region of the upper plate and the back region of the lower plate of the support ribs. The inner wall surface of the rubber core gradually produces stripes of wrinkles, and the smaller the size of the sealed drill pipe, the more obvious the wrinkles are. When the drill pipe joint is sealed by the rubber core, there is a sealing buffer zone at the shoulder, and the contact pressure change abruptly. The lower portion of the rubber core’s inner wall serves as the primary sealing area. Increasing the piston displacement appropriately can enhance the sealing performance of the rubber core. The results can provide a theoretical basis for the optimization design of the conical blowout preventer.

CALCULATION OF WELLHEAD PARTS

Wellhead rigidly connects the entire working column into a single system, takes the load arising from their weight, and transfers the entire load to the conductor. Provides insulation and tightness of the space between the columns, while at the same time allowing you to monitor the condition of the wellbore and perform the necessary technological operations. Wellhead serves as a pedestal for installing the production string lowered into the well. During drilling, blowout preventer equipment is installed on it, which is dismantled after drilling. The number of these elements depends on the number of working strings in the well. The casing head is positioned according to the sequence of running and cementing at the wellhead. They are selected during drilling taking into account the expected formation pressure after the drilled well interval. The operating conditions of the column head are quite difficult: In deep wells, the load from the weight of protective casings can exceed several hundred kilonewtons. The column head elements also absorb the pressure of the medium in contact with them. If there is H2S, CO2 in the formation fluid or gas, or if the formation water is highly mineralized, the casing is subject to corrosion. When the heating agent is injected in deep wells, their tubing head and casing head heat up to 150-250° C, and in the Northern conditions it cools down to -60° C. Violation of the reliability of the column head leads to serious accidents, and in some cases – fires and explosions In particular, the casing heads of multi-casing wells have a large mass and vertical size. Their high metal intensity and high demand require the expenditure of large amounts of steel, especially alloy steel, for their production. As the vertical size of the casing head increases, well maintenance becomes more complicated. Column heads for wellhead equipment are manufactured with different numbers of protective columns: three-, four- and five-post. The principle and design diagrams of such column heads are similar. Keywords: wellhead, casing hanger, equivalent tension, cylindrical part, flange.

Numerical simulation method and structural optimization for shearing capacity of ram blowout preventers

With the increasing demand for energy in the country, there has been a notable rise in the deployment of deep and ultra-deep wells. Consequently, drilling operations have become more complex, with greater intricacies in drilling techniques, challenging operating conditions, and varying geological factors. The size of the drill pipes has grown larger, and higher steel grades are being used, surpassing the design requirements of conventional ram blowout preventers. As a result, issues have arisen, including inadequate shear force of the ram blowout preventer to cut through the drill pipes and the potential for cut debris from the drill pipes to fall and damage the sealing elements, compromising the sealing integrity and posing a risk of blowouts.To address these issues encountered in the field, a shear analysis model for the ram blowout preventer was established based on the Johnson-Cook constitutive model and the Shear Damage fracture criterion. The reliability and accuracy of the simulation were validated through comparative experiments between simulation and laboratory trials. Furthermore, the structure of the ram blowout preventer was optimized to mitigate these challenges. Additionally, the response surface method was employed to optimize the parameters of the novel ram structure for the ram blowout preventer, followed by indoor experiments using the selected parameters. The experimental results demonstrated a significant improvement in both the shear performance and sealing capability of the novel ram blowout preventer compared to the conventional ram blowout preventer design. This advancement provides valuable insights and practical reference for on-site operations.

Applications and functions of wet fountain fittings used in pre-salt cluster of santos basin

"Fountain fitting " - deep and ultra- deep in the waters oil and natural dig it up removal for needed which is main underwater of equipment is one Petrobras well in Brazil the mouth with (Wet Christmas Tree – fountain armature ) between WCT installed (Production Adapter Base - production adapter base ) (PAB) . This equipment is a wellhead equipment used to install oil and gas wellhead, control it and control the mode of operation. There are Fontan fittings for surface (for wells drilled on land) and subsea (offshore wells). According to its construction, it is horizontal and has three steps. Fountain accessories consist of tube and belt head, Christmas tree fountain. The belt head located at the bottom of the fountain shield is used to hang the protective belt, close the gap between the pipes, etc. It is for the Pipe head to hang and seal the pump compressor pipe lowered into the well attached to the belt head. The resource head directs the product from the well to the discharge line, enabling control and monitoring of the well. The fountain armature is equipped with a pressure gauge and thermometer. BOP and fountain of the armature absolutely different equipment that it is clarify need a lot people this two underwater equipment mix it up because it can each two of them the well in the mouth is installed . Dump Blow-Out Preventer (BOP) of wells digging , completion and processing during use which is security equipment . His main components drawers (rams), annular discharge against preventers and suffocation and don't kill are lines (choke & kill lines). Fountain pipes are lowered into the well where the fountain is expected to shoot. It is necessary to hang these pipes from something at the wellhead and direct the product of the well to the outside through it, and for this, it is necessary to mold the space between the fountain pipes and the production line. In order for the fountain to pump in an optimal mode, to regulate the use of reservoir energy, it is necessary to create counter pressure at the well mouth by any means. Therefore, the equipment at the mouth of the fountain well must be able to create any back pressure in the discharge line, including closing the well. In addition, the wellhead equipment should allow to measure the pressures behind the pipe, in the discharge line, and also to inject gas or liquid into the well if necessary.

A knowledge transfer-based method for risk analysis and procedure optimization of emergency schemes

Due to insufficient knowledge of rare accidents, it is essential to transfer knowledge from source domain with sufficient cases (e.g., onshore blowouts) into target domain with limited cases (e.g., deepwater blowouts). In this paper, a knowledge transfer-based method is proposed to evaluate the performance of emergency schemes in presence of limited accident cases. By considering dynamic evolution and operational characteristics of the accident, to evaluate emergency schemes from the perspectives of emergency risk and timeliness, a hybrid model integrating dynamic Bayesian networks (DBN) and program evaluation and review technique (PERT) is applied. In the integrated model, we transferred graph structures and parameters to obtain emergency schemes based on the similarities between the source systems and target systems. On the one hand, to evaluate and control emergency risk, DBN is utilized for dynamic risk analysis of emergency operations. On the other hand, to judge the response-time requirement, an optimized PERT is applied to enhance the completion probabilities of the emergency procedures. A case study on the installation of onshore blowout preventer and offshore capping stack is applied to illustrate the applicability of the proposed methodology. The results show that equipment failure and human error are crucial risk-influencing factors leading to emergency failure. Activities duration and completion probability of emergency schemes are optimized by emergency timeliness analysis.