Drilling Unit Research Articles

Port State Control of Offshore Supply Ships, MODU and FPSO Units

The Port State Control system aims to ensure that all ships are subject to regular inspections, with particular attention to the ships of insufficient quality. To this end, during the inspection, priority is given to ships that are considered risky. Thetis database is an information system that contributes to the implementation of the Port State Control within the EU (European Unit). It contains data on inspections performed in the EU ports and the Paris Memorandum area. The Paris Memorandum has 27 member states and covers the waters of European coastal states and the North Atlantic basin from North America to Europe. The main goal of the Paris MoU (Memorandum of Understanding) is to eliminate substandard ships through a harmonized Port State Control system. Namely, inspections should ensure that ships meet international safety standards, are safe for the environment, and provide adequate living and working conditions for workers. The primary responsibility for ensuring these standards rests with the ship owner/shipper while the responsibility for ensuring such compliance rests with the flag state. The aim of this analysis is to determine the number of inspections performed in the ports of the Republic of Croatia and the Republic of Italy, to identify the cause of ship detentions and the most common deficiencies of offshore supply vessels, MODU (Mobile Offshore Drilling Units) and FPSO (Floating Production Storage and Offloading) Units. In the observed period, the impact of the crisis caused by the COVID-19 pandemic was significant, resulting in the decline in the numbers of inspections performed in 2020 and 2021. In 2022, the number of inspections increased, but it still has not reached its pre-pandemic level. During the period that was the subject of research, port state inspections in the Republic of Croatia and the Republic of Italy revealed 241 deficiencies. Five areas with the largest number of deficiencies are: Certificate & Documentation, Safety of Navigation, Fire Safety, ISM, and Life-saving appliances, which follow the trend of the lack in the areas of the Paris Memorandum. The greatest increase in deficiencies was recorded in the areas of Labor Conditions-Health protection, Certificate & Documents (Crew Certificate, Documents), Emergency System and Fire safety area, which led to an increase in the number of offshore supply ships retention during the first half of 2022.

The Monitoring of Abnormal Fluid Properties Based on PCA Technique as an Alternative Strategy to Support Autonomous Drilling Operations

Summary The well drilling process requires constant monitoring to ensure that the properties of the drilling fluids remain within acceptable ranges for safe and effective operation of the well drilling process. The present work developed a principal component analysis (PCA)-based methodology for diagnosing anomalies in drilling fluids, and detecting and identifying abnormal drilling fluid properties during well drilling operations. The main novelty of the present work regards the application of multivariate techniques for diagnosing anomalies (faults) in drilling fluids, increasing the literature on fault diagnosis techniques applied to the petroleum industry, and producing a promising methodology for field applications. The proposed technique was implemented and validated in a pilot drilling fluid production unit through continuous online monitoring of the conductivity, density, and apparent viscosity of drilling fluids. Model training was carried out with data collected during assisted normal operation, allowing detection of abnormal conditions with less than 1% of false positives and less than 0.5% of false negatives. Additionally, the proposed methodology also allowed the correct diagnosis of the observed faults. The results indicated that PCA-based approaches can be used for the online monitoring of drilling fluid properties and fault diagnosis in real well drilling operations.

Mechanistic research on the complex motion response of a TLP in a tender-assisted drilling state

In this study, nonlinear motion characteristics have been studied in the coupled behavior of a Tension Leg Platform (TLP) combined with a Tender-assisted Drilling Unit (TADU). A time-domain numerical model has been established that accounts for the nonlinear behavior of mooring systems and hydrodynamic interference. Experiments are performed to verify the numerical model. Nonlinear motion characteristics of the steady-state response of the time-domain results are analyzed using Poincaré mapping and fast Fourier transform. The focus of this study is on investigating the motion response of the TLP platform in three degrees of freedom under coupled states. The surge motion is found to mainly consist of the wave frequency component and the half-wave frequency subharmonic component, while the wave-frequency, subharmonic, and super harmonic vibration components are observed in both heave and pitch motions. Three types of nonlinear regimes, namely chaos, transition, and multiple periodic, are identified in the heave and pitch motions under different wave conditions.

Case Study: Conductor-Integrity Monitoring in Subsea Wells in Harsh Environments

_ A decade-long project to monitor drilling operations on subsea wells in harsh environments has delivered interesting results. Subsea production and exploration wells are subjected to loads from the drilling riser and subsea blowout preventors (BOP). The latter have grown in size and weight over time, resulting in larger wellhead loads. The main task of a subsea conductor is to transfer these loads into the seabed. The bending load applied on the wellhead is transferred into the conductor, which again transfers the loads through the cement and into the soil. In cases where the load exerted on the soil and cement exceeds the capacity, the soil around the conductor might fail. The cement filling the cavity between the conductor and the soil can also crack and consequently lose its intended function. This support degradation reduces the conductor’s ability to support the well. 4Subsea’s Subsea Wellhead Integrity Monitoring (SWIM) service for operations on subsea wells has now been in action for more than a decade. Sensors monitoring the motion and loads near the subsea wellhead have been mounted on more than 300 drilling campaigns (Fig. 1). In recent years, more than 70% of the drilling operations with semisubmersible drilling rigs on the Norwegian Continental Shelf (NCS) have been monitored using SWIM. As a part of the service, integrity parameters showing whether the conductor gives the intended amount of support are calculated. A major finding is that loss of conductor support during drilling operations has been observed in several of these campaigns, with different integrity issues detected. In at the Deep End Wells in the North Sea, the Norwegian Sea, and the Barents Sea are often developed as subsea fields. The typical setup while drilling these wells utilizes a mobile drilling unit (semisubmersible or drillship) with a marine riser and subsea BOP. The well foundation must be designed to withstand the imposed loads. In accordance with Norwegian Safety Authority facility regulations, wells and their foundations must follow strict regulations. These include that the conductor shall provide structural integrity of the well during its service life, and that it shall be evaluated with respect to structural loads and fatigue. Subsea wells can be divided into two categories based on the type of support of the respective conductor. - Supported conductors are the most-common configuration for subsea production wells in harsh environments, with a template structure supporting the conductor. - Unsupported conductors are used for exploration and production wells in less-harsh environments. During well foundation design, there are typically three different failure modes to consider. - Extreme load failure (ULS, ALS) of the wellhead system and supporting structures - Fatigue failure (FLS) of the wellhead system and supporting structure - Failure of the soil support and cement around the conductor SWIM covers both fatigue monitoring and detection of issues with the soil and cement support.

Dynamic drift-off warning limits for dynamically positioned MODU with Deepwater Artificial Seabed (DAS) system coupling

A new Deepwater Artificial Seabed (DAS) drilling system, which enables the shallow-water rated drilling equipment to operate in deep and ultra-deep water, has been developed for dynamically positioned Mobile Offshore Drilling Unit (MODU), with a focus on key issues of well access and riser design. Nevertheless, the MODU may drift-off due to the critical failures of the dynamic positioning (DP) system and thus the well integrity will be gravely threatened. This study is committed to establishing the quantitative criteria of drift-off warning limits, which consist of the yellow limit, red limit and physical limit, for dynamically positioned MODU with the coupled DAS drilling system. To achieve this aim, a three-phase methodology is proposed on the basis of a fully coupled model of the MODU-DAS drilling system. Furthermore, a hybrid method integrating the orthogonal experimental design, back propagation neural network, and Garson's algorithm is developed to systematically investigate the importance of the correlative influencing factors on the drift-off warning limits in consideration of both the efficiency and accuracy of the numerical calculations. The validity of the proposed methodology is demonstrated by a case study. The results indicate that the dynamic drift-off warning limits are able to assist in decision-making of safe DP operations on the MODU and the operating depth of the artificial seabed is the most critical factor affecting the envelope of drift-off warning limits. These findings and recommendations could improve the safety of DP drilling operations.

Excavation by snake robots with fins and a drill

In this study, we developed a snake robot composed of fins and a drill to excavate and move underground. In addition, we proposed a method of underground motion using a robot. The underground motion is divided into anchoring and drilling motions. The anchoring motion fixes the robot by anchoring the fins attached to its sides on the tunnel wall using articulated motions. This anchoring motion is required to withstand the reaction forces during the drilling motion and propel the robot. The snake robot has multiple joints; thus it can have various shapes. By changing the shape of the robot, it can accommodate itself to change the tunnel diameter. The drilling motion creates a forward space using the robot's drilling unit. This motion uses the front as well as the sides of the drill for efficient excavation. This reduces the number of insertions and removals, thereby decreasing excavation time. The effectiveness of the anchoring and drilling motions was tested using the robot in an environment simulating an underground tunnel. It was confirmed that the robot could fix, excavate, and withstand reaction forces.

Application and Development of Fiber Optic Gyroscope Inertial Navigation System in Underground Space

Fiber Optic Gyroscope Inertial Navigation System (FOG-INS) is a navigation system using fiber optic gyroscopes and accelerometers, which can offer high-precision position, velocity, and attitude information for carriers. FOG-INS is widely used in aerospace, marine ships, and vehicle navigation. In recent years, it has also played an important role in underground space. For example, in the deep earth, FOG-INS can be used in directional well drilling, which can enhance recovery in resource exploitation. While, in shallow earth, FOG-INS is a high-precision positioning technique that can guide construction in trenchless underground pipelaying. This article extensively reviews the application status and latest progress of FOG-INS in underground space from three aspects—FOG inclinometer, FOG drilling tool attitude measurement while drilling (MWD) unit, and FOG pipe-jacking guidance system. First, measurement principles and product technologies are introduced. Second, the research hot spots are summarized. Finally, the key technical issues and future trends for development are put forward. The findings of this work are useful for further research in the field of FOG-INS in underground space, which not only provides new ideas and directions for scientific research, but also offers guidance for subsequent engineering applications.

A study on new machining method applied to a collaborative robot for drilling

In the assembly of aircraft fuselages, manual hole drilling is conducted in some cases instead of applying robotic drilling due to the issues of burr formation and vibration. In manual operation, tool feeding is realized by applying force to the tool. A prototype system was developed in which a load is applied from the upper side of the spindle by a weight to move a spindle in a vertical downward (CLF method). Drilling in aluminum using this system did not lead to crown-shaped burr formation or irregular vibrations which are often problems in robotic machining. The level of the load applied to the tool becomes an important parameter in the CLF method. To minimize the damage generation, it may be important to adjust the load to the minimum level required for cutting and tool feed. Given such a tool feed system, a drilling unit could be composed from general purpose units such as a shaft and bushing combination. Robotic machining with this type of drilling unit is expected to lead to significant labor savings and improved machining accuracy in machining that is currently conducted manually.

Design of a Display Structure for an Anti-Collision System of Offshore Drilling Units Based on the Digital Twin Concept

The drill floor of an offshore drilling facility is equipped with a collision avoidance system to prevent collisions between moving equipment. In this paper, we present the visualization of the collision avoidance system using the digital twin concept. By classifying the core technologies of the digital twin, the elements necessary for the visualization of the collision avoidance system are derived, and the information for visualization is organized. We conduct 3D visualization of equipment and design IO devices necessary for the visualization. The movement of the floater is considered, and a database is built to efficiently search for the information required for the retrieval of stored 3D information. A collision detection situation is generated by operating the equipment using the input device required for simulation. Collision information is displayed as designed, and it is confirmed that the switching of the display between the present and past time is operating normally. The entire system functions normally as designed, including the input/output with other databases and equipment operation. Implementing a digital twin for an offshore platform is a time-consuming and costly process. It is expected that the improved anti-collision system can be expanded for the digital twin of an entire offshore platform.

Transient response of an innovative Deepwater Artificial Seabed (DAS) system under tendon failure conditions

An innovative Deepwater Artificial Seabed (DAS) drilling system is developed to overcome the demanding technical and economic limitations for offshore drilling activities in deep and ultra-deep waters, with a focus on important issues of well access. However, tendon failure poses significant threats to the well integrity of the DAS drilling system. This study is committed to investigating the transient effects of tendon failure on the response of the fully coupled DAS drilling system. A nonlinear model, which couples the Mobile Offshore Drilling Unit (MODU), artificial seabed, riser system, intact and fractured tendons, is established firstly. Based on this, the transient response characteristics are systematically investigated in consideration of tendon breakage scenarios, covering the artificial seabed motion, the tendon tension, the strength of the drilling riser and tieback casing systems. The results indicate that the transient motion responses of the artificial seabed behave as large translational and rotational movements nonlinearly under tendon failure conditions. However, the heave motion of the inner artificial seabed, by contrast, is quite small due to the decoupling effect between the outer and inner artificial seabed in the vertical direction. Besides, the maximum tensions in neighboring tendons increase sharply caused by the transient effects of tendon failures, which may lead to cascading failure effect, even a total loss of the DAS drilling system. These findings can contribute to the safe design and operation of the DAS drilling system.

Dynamic management of residual operational risk of offshore drilling units

Dynamic management of residual operational risk of offshore drilling units

Optimal Choice of Travelling System Structure depending on Design Parameters of Hoisting System in Drilling Units of Oil and Gas Wells

Most drilling rigs are designed based on the max static load on the hook of great travelling system structure as 6×7. But when change the depth of the well, the load on the hook changes, so it was necessary to determine the travelling system structure, which ensures the best design indicators of hoisting system.
 This research studied the impact of travelling system structure on design parameters of hoisting system and the best indicators of hoisting systems at less drilling lines number suitable with max allowable load on hook for oil and gas wells drilling units.
 In this work, A methodology depending on graphical solution for hoisting system indicators curves has been developed. (MATLAB) has been used in order to develop a program that facilitates the application of this methodology and accelerate the work. The most important technical parameters for different drilling unit, in addition to the allowable hookload, by using the most important design indicators that positively or negatively affecting the system with changing travelling system structure. This program depending on graphical solution for set of these indicators in relation with number of drilling lines by finding equilibrium point between positive and negative effects that has the algebraic sum of the slopes is as close as possible to zero. This point represent optimal drilling lines compatible with hookload at practical technical parameters for drilling units.
 This study achieves the best indicators for hoisting system working at ideal travelling system and decrease the time required for drilling by increasing hook velocity rate by 12% and the efficiency of hoisting system by 10%. In addition, the lengths of drilling line rate decreased by 40% that cause reduction in material cost and achieving better economic feasibility in comparison with design travelling system.

Holistic process monitoring with machine learning classification methods using internal machine sensors for semi-automatic drilling

Since one third of rivet holes during aircraft assembly are produced with semi-automatic drilling units, in this work reliable and efficient methods for process state prediction using Machine Learning (ML) classification methods were developed for this application. Process states were holistically varied in the experiments, gathering motor current and machine vibration data. These data were used as input to identify the optimal combination of five data feature preparation and nine ML methods for process state prediction. K-nearest-neighbour, decision tree and artificial neural network models provided reliable predictions of the process states: workpiece material, rotational speed, feed, peck-feed amplitude and lubrication state. Data preprocessing through sequential feature selection and principal components analysis proved to be favourably for these applications. The prediction of the workpiece clamping distance revealed frequent misclassifications and thus, was not reliable.

Peri-İmplant Kemik Defekti Tipinin Yerleştirme Torku ve Rezonans Frekans Analizi Üzerine Etkisi: İn Vitro Çalışma

Objective: The aim of the present study is to investigate the effects of different peri-implant bone defects on primary stability and the correlation between insertion torque (IT) and resonance frequency analysis (RFA) measurements. Material and Methods: Fourty implant beds were prepared in artificial bone blocks using the 3D surgical guide. Implant osteotomies were divided into 5 groups (n=8) according to defect type: i) no peri-implant bone defect (control), ii) a dehiscence defect, iii) a fenestration defect on the middle part, iv) a fenestration defect on the apical part and v) a circumferential defect. Implants were inserted by using a surgical drilling unit with torque control and RFA measurement were done. Results: IT values for the control group were significantly higher than the other groups (p<0.001). The results of IT measurements for dehiscence defect group were significantly greater when compared to fenestration and circular defect groups (p<0.01). Implant stability quotient (ISQ) values for the control group were significantly higher than other groups (p<0.05). In addition, the ISQ values for the dehiscence defect group were significantly lower when compared to fenestration defect groups (p<0.001), and ISQ values for the circular defect group were significantly lower than any other groups (p<0.001). IT values and, ISQ values are moderately correlated (p=0.013, r=0.388). Conclusion: The location of peri-implant bone defect affects RFA measurements more than IT. However, IT seems to be correlated with bone implant contact. Therefore, in the case of peri-implant bone defect, IT measurement may be preferred for evaluation of primary stability.

Wellhead fatigue analysis considering the effect of wind-sea and swell waves by using Univariate Dimension Reduction Method

In recent years, the observation of dynamic motions in wellhead structures during drilling operations turned wellhead fatigue into a great concern for the oil industry. As stated by DNV in its Recommended Practice E104 (DNVGL, 2018), the fatigue damage evaluation demands an accurate representation of environmental loads acting on the whole drilling structure, including rig, drilling riser and BOP/LMRP. In terms of computational costs, this representation can make the fatigue analysis very expensive. A high number of loading cases may be needed to take into account the statistical independence between environmental parameters, mainly when wind-sea and swell waves are taken into account. To solve this issue, this paper proposes the use of the Univariate Dimension Reduction Method (UDRM) to compute the fatigue damage in wellhead structures considering the effects of both types of waves. The main advantage of this procedure is that it replaces the solution of the four-fold integral associated to the problem by the solution of four one-dimensional integrals, which drastically reduces the number of numerical simulations required in the fatigue assessment. The method is applied to two study cases considering the environmental conditions of the Brazilian coast. In the first, the drilling unit is a semi-submersible platform, while in the second case a ship-based drilling unit is considered. The obtained results indicate a substantial reduction in computational costs without loss of accuracy of UDRM when compared to a Monte Carlo Simulation-based approach.

Dynamic probabilistic risk assessment of decision-making in emergencies for complex systems, case study: Dynamic positioning drilling unit

Decision-making in emergency situations is a risky and uncertain process due to the limited information and lack of time. Some key problem parameters, such as the time required to complete important response tasks, must be estimated and are therefore prone to errors. Other parameters, such as the probability of occurrence of a consequential event, will typically change as the response operation progresses. As a result, there should be a dynamic probabilistic risk assessment framework to assess the risk level of decision scenarios and facilitate the decision-making process.In this paper, a methodology for dynamic probabilistic risk assessment of decision making in emergencies for complex marine systems is proposed. In this method, a dynamic event sequence diagram is introduced that helps to quantify events probabilities as a function of time, as well as environmental and operational variables, considering events interdependencies and uncertainties. In addition, the effects of time required11Time required refers to the time needed to perform each level of decision-making process (detection, diagnosis, decision-making, execution). and time available22Time available is the time remaining before an accident happens in a system. It is derived from the dynamic simulator of the system. The dynamic simulator calculates the time remaining before a collision based on the system components status, operation and environmental conditions at the time of incident. for performing a decision in emergency are considered in the risk model. In this methodology, probabilistic models including Bayesian network and Monte Carlo simulation are utilized to quantify the uncertain behavior of the decision-making process in complex marine systems.A computational study is also conducted to evaluate the methodology performance, in terms of effectiveness and efficiency. Computational results show that the proposed approach can obtain optimal solutions for large and practical problem sizes.

E&P Notes (July 2021)

E&P Notes (July 2021)

3D-Printing Replication of Porous Media for Lab-Scale Characterization Research.

Simplifying fluid-flow physics in conventional reservoirs is convenient by assuming uniform lithology and system-geometry with minimal rock/hydrocarbon interactions. Such simplification restrains mathematical models’ ability to simulate unconventional reservoirs’ actual flow behavior and production performance. Researchers can achieve precise adaption for the physics of fluid flow in porous media if they geometrically characterize the system under study appropriately, and there are minimal interactions indeed. 3D-printed replicas of porous-rock samples obey this criterion. In this work, we used image-processing tools used for creating presentable porous and permeable replicas of different scales and configurations of the petroleum system from lab-scale to field-scale. The workflow of 3D-printed replicas creation is presented for replicas of conventional core samples, naturally and synthetically fractured cores, geological drilling units of multistage fractured horizontal wells, and full-field models, e.g., Norne field in Norway. These samples are ideal for experimentally testing the validity of the analytical or numerical models of oil and gas reservoirs in the laboratory, along with judging the quality of reservoirs’ characterization. These replicas’ ideality of these results from limited uncertainties of the geometry of the system under study and fluid/rock interactions because of the uniform composition. For validation purposes, 3D-printed replicas with different materials and 3D-printing technologies were created based on a reconstructed image-processed CT scan of their original Berea sandstone. These replicas were tested for storage capacity (porosity) and transport capacity (permeability) and compared with their original sample’s capacities. The matched results proved replicas’ ability to be used in oil and gas laboratory experimental research.

Construction of vertical drainage wells using corrosion resistant materials

Vertical drainage wells in terms of construction technology and design do not differ from wells for irrigation. They are not deeper in-depth than irrigation wells and are generally 40-70 m. The main task of vertical drainage wells is land reclamation. They, depending on natural and economic conditions, serve on 5-120 hectares of area. In many areas, vertical drainage wells serve a dual purpose; land reclamation and irrigation of agricultural crops. Water intake wells, including vertical drainage wells, are characterized by a decrease in their flow rates during operation. To ensure the stable operation of the irrigation and drainage system, where water intake wells are operated, repair and restoration work is carried out on them, aimed at increasing flow rates. For the construction of vertical drainage wells in the Sirdarya river basin, steel pipes and filters are mainly used, which corrode in an aggressive environment. In the water intake zone of the well and the metal corrosion process, the colmatation process also occurs. All of them are the main reasons for the decline in well production rates. The carried out repair and restoration measures are aimed at destroying the structure of corrosion and clogging products. In practice, mechanical, physical, biological, and chemical methods are used to clean the filters of water intake wells. They all have their own technology and equipment. However, all these works do not exclude the repeatability of the process. Repetitive workover will come to ineffective, the stage of good concertation is approaching. It is known that polymeric materials do not corrode. They work steadily in aggressive environments. To prevent the corrosion process, polymeric-seam pipes were used as a filter frame and a casing for the construction of vertical drainage wells. Two pilot wells were built on the territory of the Chiyili district of the Kyzylorda region of the Republic of Kazakhstan. The wells were drilled with a rotary drilling unit with backwash. Pure water (irrigation) was used as drilling fluid. To form a gravel pack in the annular zone of the casing, gravel-sand material from the Jailma quarry was used. The material was brought by rail and road transport. Pipe sections were prepared on the surface of 10 meters. Steel rings were put on the pipe from both ends of each section; their connection in the barrel was made by electric welding. The results showed that in the initial period of operation, a decline process was observed. In further exploitation, the well flow rate stabilized. As a result of construction using pipes and filters made of polymer material, the effect was achieved in terms of water volume more than 3 times and in terms of service life 4.2 times compared to a metal filter well.

Retrospective in silico evaluation of optimized preoperative planning for temporal bone surgery

PurposeRobot-assisted surgery at the temporal bone utilizing a flexible drilling unit would allow safer access to clinical targets such as the cochlea or the internal auditory canal by navigating along nonlinear trajectories. One key sub-step for clinical realization of such a procedure is automated preoperative surgical planning that incorporates both segmentation of risk structures and optimized trajectory planning.MethodsWe automatically segment risk structures using 3D U-Nets with probabilistic active shape models. For nonlinear trajectory planning, we adapt bidirectional rapidly exploring random trees on Bézier Splines followed by sequential convex optimization. Functional evaluation, assessing segmentation quality based on the subsequent trajectory planning step, shows the suitability of our novel segmentation approach for this two-step preoperative pipeline.ResultsBased on 24 data sets of the temporal bone, we perform a functional evaluation of preoperative surgical planning. Our experiments show that the automated segmentation provides safe and coherent surface models that can be used in collision detection during motion planning. The source code of the algorithms will be made publicly available.ConclusionOptimized trajectory planning based on shape regularized segmentation leads to safe access canals for temporal bone surgery. Functional evaluation shows the promising results for both 3D U-Net and Bézier Spline trajectories.