Relief Wells Research Articles

Simulation Research on the Dual-Electrode Current Excitation Method for Distance Measurements While Drilling

Based on a comprehensive analysis of the existing methods for measuring adjacent well distances, along with their advantages and disadvantages, this study employs theoretical analysis, simulation experiments, and other comprehensive research methods to investigate a distance measurement method based on current excitation. In response to the need for measuring and controlling the connection of relief wells, a method utilizing dual-electrode current excitation during drilling is proposed. This approach facilitates synchronous excitation measurements while drilling, significantly reducing both time and costs while ensuring safety and efficiency, making it particularly suitable for the connection operation of relief wells that involve safety risks. Firstly, this paper establishes a drilling with measurement model corresponding to the excitation mode, which derives the calculation formulas for the target casing current amplitude attenuation, as well as the induced magnetic field distribution within the formation. Additionally, it provides the calculation methods for determining the target well distance and azimuth direction. Lastly, the impact levels of various key factors are verified through numerical calculations and simulation analyses, which confirm the correctness and effectiveness of this distance measurement method. The findings from this research establish both a core theoretical foundation and a technological basis for the real-time measurement of adjacent well distances during relief well operations.

Experiments on suffusion of coarse soils from an ageing British dam

This study presents a laboratory investigation on the susceptibility of suffusion in soil samples collected from a very old earth dam. The dam, rebuilt around 1800, is composed of two earth fills and lacks a clay core or filtration components, making it vulnerable to internal erosion. Following an inspection in 2006, concerns were raised about the dam’s vulnerability to internal erosion during strong floods. Boreholes and vibro-cores were performed to collect samples, which were then tested for suffusion susceptibility. The study found that four out of six samples were highly susceptible to suffusion erosion, with the erosion process starting at gradients much lower than unity. The opposite was observed for samples with fines content greater than 30% and showing some plasticity. The results were compared to predictions from seven geometric criteria found in the literature, but none of the methods could forecast the behaviour of all tests. The study highlights the need for laboratory tests when there is no agreement between the predictions from available criteria. The findings of this study were used to inform the rehabilitation of the dam, which included installing sand filters designed to capture the smallest particles and relief wells distributed along the entire length and height of the eastern embankment. The study demonstrates the importance of assessing suffusion susceptibility in embankment dam safety control and the need for laboratory tests to validate predictions from geometric criteria.

Relief well as liquefaction mitigation option in Mpanau, Sigi, Central Sulawesi, Indonesia

The liquefaction disaster that occurred in Central Sulawesi in September 2018 was not only in the form of flow liquefaction but also a sand boil. Sand boils are caused by excess pore water pressure (PWP) which causes sediment ejecta due to water pressure within the ground. This research focuses on the use of relief wells to relieve excess PWP. During the 2018 disaster, the research location in Mpanau, Sigi, Central Sulawesi, had many sand boil points and the emergence of new water springs after the earthquake. At this point, the increase in PWP presumably resulted from a leaking groundwater basin, thus providing additional pressure. The method used was calculating the Ejecta Potential Index (EPI) and modelling with Seep/w. This calculation determined the amount of PWP that could be released to maintain the comparison between PWP and effective stress. This comparison is also known as the PWP (Ru) ratio and should be kept at less than 0.8, indicating the absence of liquefaction in the layer. This analysis was carried out with the initial conditions without wells and after the presence of wells, then assessing the distance of the wells to eliminate artesian pressure. It was concluded that this mitigation method is appropriate for areas that have groundwater basins with layers prone to aquifer leakage to reduce additional PWP.

Simplified Calculation Method for Active Anti-Floating of Elliptical Basements by Relief Wells

Currently, there are two main types of anti-floating methods for underground structures; one is the passive anti-floating method represented by anti-draft piles, the other is the active anti-floating method which focuses on interceptor-discharge pressure-reducing (IDPR). In the design of an IDPR anti-floating system, the relief well system situated within the cut-off wall serves as the primary drainage channel. The determination of the seepage field distribution within the multi-well system is vital for the overall design. For the seepage field analysis of the IDPR anti-floating multi-well system, currently numerical analysis is usually used, and there is a lack of simplified analysis methods. The simplified analysis methods already available are based on the uniform distribution of wells in circular pits, while the conversion of non-circular pits into circular pits produce large errors, which are not conducive to promoting the use of the method. To address this, we propose a simplified calculation approach suitable for multi-well systems (arbitrary layout) within elliptical pits. The analytical solution of non-uniformly distributed wells in circular pits is deduced through the principle of superposition. Then, the ellipse is mapped into a circle by using conformal mapping. The resistance coefficient method is adopted, and the internal and external seepage fields are connected in series to obtain the total flow rate, as well as the distribution of the seepage field. This is based on the consideration of the permeability of the waterproof curtains and the bypassing seepage. According to the verification of the calculation example, the results of the simplified algorithm are similar to the results of the finite element method, which proves the accuracy of the method; at the same time, when applied to the actual engineering, the obtained calculation results coincide with the measured data, which proves the practicability and reliability of the method. The simplified method can provide an effective way to design an IDPR anti-floating system.

Research on Anti-Seepage Technology of Basement in Soft Soil Area by Drainage

In recent years, the modernization process of cities has been accelerated, and the scale of basement construction has been continuously expanded. The groundwater table in the southern soft soil areas is usually high, and the water pressure carried by the basement floor is often large, thus the accidents of leakage from the floor and exterior walls occur from time to time, which seriously affects the safety and use function of the basement. In this paper, based on a basement project in a soft soil area, a method of using drainage for anti-seepage treatment is proposed. By placing large diameter sand-free concrete relief wells at appropriate spacing in the basement, the seepage water in the basement is channeled into the relief wells through sand-free concrete to play the role of decompression and anti-seepage. The practice results show that the drainage system can effectively solve the leakage problem of basement floor with low cost.

Analysis and Experimental Study on Location Exploration of Relief Well

As oil and gas extraction continues to expand and deepen, the importance of relief wells becomes increasingly evident. The positioning and detection technology of relief wells is a critical technology that plays a significant role in ensuring the safety and success of relief well construction. This article focuses on the positioning and detection technology of relief wells, analyzing existing technologies and identifying issues such as difficulties in trajectory control and susceptibility to magnetic field interference, leading to low positioning accuracy and ineffective relief wells. To address these problems, simulation experiments were conducted using coils and probes on an experimental platform to replicate the positioning and detection measurements of relief wells, followed by comprehensive analysis of the experimental data.

Magnetic Ranging Method for Horizontal Section Spacing Control of Cluster Wells

Summary Interwell fracture interactions are becoming an increasing problem with the large-scale exploitation of shale gas. High precision ranging technology is required for controlling the horizontal section spacing in cluster horizontal well drilling projects. The existing magnetic ranging technology has achieved remarkable application effects in the drilling engineering of twin horizontal wells, connected wells, and relief wells. But the maximum detection range cannot meet the needs of cluster horizontal well drilling engineering. A magnetic orientation sub connected to the nonmagnetic drill collar was designed to mark the position of the wellbore being drilled. Compared with the conventional magnetic sub connected to the drill bit, the magnetic orientation sub has a higher magnetic moment, is closer to the inclinometer, and has less effect on the build-up ability of the drilling tool. Although the effect of the magnetic orientation sub on the azimuth measurement is small when the azimuth angle is equal to 90° or 270°, the effect cannot be neglected in most cases. Therefore, we develop a computational model of the azimuth that considers the influence of the magnetic orientation sub. A new calculation model of distance and direction from the wellbore being drilled to the existing wellbore is developed to realize the ranging every 30 m or so. And the simulation experiment shows that the calculation accuracy of the distance and direction can meet the field needs of cluster horizontal well drilling engineering.

Safety analysis of the Żelazny Most tailings pond: qualitative evaluation of the preventive measures effectiveness

Abstract In this paper, a qualitative safety analysis of the Żelazny Most tailings pond is addressed. This object is one of the largest facilities of this type in the world being a crucial element in the technological line of copper production in KGHM Polska Miedź S.A. The assessment of the effectiveness of two types of preventive measures, i.e., relief wells and loading berms, is investigated based on displacement and stability analysis of two 2D cross-sections in a technical section of the dam. The study shows that the considered preventive measures generally have a positive impact on increasing the safety level of the structure during its further raise. In particular, their effectiveness is most evident when they are applied simultaneously. It is eventually suggested that the selection of final solutions to be applied on the facility should be based on the quantitative 3D analysis.

Lessons Learned and Corrective Actions from BSEE Initiated Unannounced Source Control Exercises In 2018–2019

Government initiated unannounced exercises (GIUEs) conducted by the Bureau of Safety and Environmental Enforcement (BSEE) provide operators a challenging but fair opportunity to demonstrate their response capabilities. When a source control GIUE is initiated, personnel from both industry and government are expected to perform their response roles in real time as they would in an actual incident. Source control GIUEs are also used to objectively assess spill preparedness and identify any deficiencies and vulnerabilities. The intent of this report is to share appropriately redacted lessons learned and corrective actions that transpired from BSEE source control GIUEs for the benefit of regulators, operators, and other responders seeking to improve upon their existing capabilities. During the 2018 and 2019 fiscal years, the BSEE Oil Spill Preparedness Division (OSPD) conducted 29 GIUEs. Of those 29 GIUEs, 17 were functional exercises and 12 were full-scale exercises involving the deployment of response equipment. The Source Control GIUEs, which comprised 7 of the 29 exercises, intended to assess a broader scope of readiness as compared to the more familiar capping stack soft shut-in scenarios from past years. OSPD coordinated with numerous stakeholders to ensure the appropriate experts were involved in the GIUE planning process. These interdisciplinary planning teams collaborated to develop previously unexplored but relevant scenarios involving surface blowouts, relief wells, and subsea well interventions. BSEE's intention is to maintain this coordinated effort to produce new and challenging scenarios for the purpose of ensuring maximal preparedness for all potential and plausible response conditions. Increasing the source control GIUE program's scope and scale in this directed manner resulted in significant lessons learned and corrective actions relevant to both the regulated community and the regulators. OSPD has compiled and summarized these results for distribution. Lessons learned were classified utilizing the following 6 categories adapted from the Homeland Security Exercise and Evaluation Program (HSEEP) Guidance: Communications, Leadership and Management Processes, Organizational Structures, Plans or Procedures, Resources, and Training. With regards to corrective actions, OSPD issued these directives with the intent of providing operators an opportunity to resolve deficiencies identified during the source control GIUEs to ensure adequate preparedness and are not to be considered punitive. This paper will present a redacted summary of these lessons learned and corrective actions identified during the 2018 and 2019 GIUE years for the benefit of everyone involved in spill response preparedness.

Multiobjective Optimization of Relief Well Operations to Improve Levee Safety

AbstractThe factor of safety (FS) of levees and floodwalls with relief wells to underseepage is predicated on the blanket thickness and relief well performance. In urban environments with limited r...

Petroleum Well Blowouts as a Threat to Drilling Operation and Wellbore Sustainability: Causes, Prevention, Safety and Emergency Response

Sustainability in petroleum wells drilling operation systems strongly depends on the use of sustainable materials and a set of technical and safety measures that lead to the survival and proper operation of drilling rig equipment's and personnel. Adherence to the highest levels of standards of tools, materials and methods, although always recommended as the most important option for advancing a safe drilling operation and completing the well efficiently, low risk and stable, but drilling operation is inherently a battle with underground challenges and unexpected dangers. Learning from past such well blowout events and the problems they pose to rapidly control is essential to reduce future impacts including injuries, damage and emissions. Such analysis offers guidance for adapting working practices to improve both prevention and emergency response to such incidents. The causes of blowout during drilling and the necessary technical and safety measures to adopt are reviewed, highlighting how best practices can prevent blowout incidents by improving responses to early warning signals. The particular risks associated with potential shallow gas blowouts are identified and described with the aid of a case study associated with a catastrophic blowout of an onshore well in Iran and the methods used to ultimately control it. The multiple causes of the incident relating to defects in safety systems, equipment and operating procedures are addressed. Lessons learned from the incident reveal the complexity of well control once a blowout incident has occurred and developed into a surface fire. from the stage of the incident to fire control. There is a need for further research into top-hole well kill techniques for wells in a blowout state, as drilling bottom-hole relief wells takes substantial time, during which much surface damage, resource loss and emission typically occurs.

Petroleum Well Blowouts as a Threat to Drilling Operation and Wellbore Sustainability: Causes, Prevention, Safety and Emergency Response

Sustainability in petroleum wells drilling operation systems strongly depends on the use of sustainable materials and a set of technical and safety measures that lead to the survival and proper operation of drilling rig equipment's and personnel. Adherence to the highest levels of standards of tools, materials and methods, although always recommended as the most important option for advancing a safe drilling operation and completing the well efficiently, low risk and stable, but drilling operation is inherently a battle with underground challenges and unexpected dangers. Learning from past such well blowout events and the problems they pose to rapidly control is essential to reduce future impacts including injuries, damage and emissions. Such analysis offers guidance for adapting working practices to improve both prevention and emergency response to such incidents. The causes of blowout during drilling and the necessary technical and safety measures to adopt are reviewed, highlighting how best practices can prevent blowout incidents by improving responses to early warning signals. The particular risks associated with potential shallow gas blowouts are identified and described with the aid of a case study associated with a catastrophic blowout of an onshore well in Iran and the methods used to ultimately control it. The multiple causes of the incident relating to defects in safety systems, equipment and operating procedures are addressed. Lessons learned from the incident reveal the complexity of well control once a blowout incident has occurred and developed into a surface fire. from the stage of the incident to fire control. There is a need for further research into top-hole well kill techniques for wells in a blowout state, as drilling bottom-hole relief wells takes substantial time, during which much surface damage, resource loss and emission typically occurs.

Telemetry Tracking During Directional Drilling

The article discusses the main features of the organization of telemetry in directional drilling. The constant increase in the complexity of the conditions for the development and operation of fields, oil and gas production, an increase in the intensity of development of already explored fields due to horizontal and cluster drilling required a significant increase in the requirements for the accuracy of diagnostics and active control of the spatial position of the field. In general, the accuracy of measurements and the efficiency of their processing largely determine the cost of well construction. Directional drilling is one of the well construction methods. The most effective directional drilling application is the development of fields located in water areas, in swampy or rugged terrain, where the construction of drilling rigs may violate the requirements for environmental protection and environmental safety. Directional drilling is also widely used in the creation of relief wells for killing blowouts, for forming multilateral wells or deviating the lower part of the well along the productive horizon in order to increase drainage. Well profiles may vary, but the top of the deviated wellbore must be vertical, followed by a deviation of the calculated azimuth. Therefore, the main task of the telemetry system in directional drilling is to constantly monitor the planned trajectory, as well as to maintain the bit trajectory within the corridor that runs inside the open formation.

Numerical investigation of relief well performance for decreasing uplift pressure under embankment dams

Drainage systems for embankment dams are arrangements that collect seepage water in downstream areas. A relief well downstream of a hydraulic structures is one way to reduce the water pressure underneath the structure and thereby improve stability. The design of relief wells includes the determination of the distance of the relief wells from each other, their location, and the well diameters. This study investigates the effects of relief wells on uplift pressure in earthen dams. Solutions were obtained by the finite element method which was used to assess different configurations of the relief wells. For validation, a comparison between analytical solutions and numerical calculations shows good agreement for uplift pressure prediction. Reducing the distance between relief wells or increasing the well diameters results in a reduction of uplift pressure. A two-row arrangement of relief wells showed that a zigzag deployment is superior to a non-zigzag deployment. Linear and nonlinear regression relations are presented for uplift pressure prediction.

A Theoretical Model of Residual Magnetic Field around a Pre-Magnetized Casing String

In the field of petroleum drilling engineering, passive magnetic ranging technology is generally used for specialized drilling operations such as connecting relief wells, preventing wellbore collisions, guiding parallel horizontal wells, etc. Although pre-magnetized casing strings have been used to improve the detection distance and accuracy, the theoretical mechanism is not well understood. Based on the equivalent current model of a permanent magnet, a theoretical magnetic field model around the pre-magnetized casing string was established by using the vector potential method and vector superposition principle and validated by the COMSOL Multiphysics software. Our results show that connecting pre-magnetized individual casings with homogeneous magnetic poles can enlarge the magnetic induction intensity around the total casing string. Furthermore, the magnitude close to the casing coupling is significantly larger than that close to the middle of the individual casing. Connecting pre-magnetized individual casings with heterogeneous magnetic poles results in a low magnetic induction intensity around the total casing string. In order to improve the detection distance and accuracy of the magnetic ranging, the pre-magnetized individual casings should be connected with homogeneous magnetic poles. The results of this study can provide guidelines for the development of passive magnetic ranging technology.

Transient Antiseepage Analysis of the Relief Well in Beijiang Dike

In this paper, the seepage finite element method (FEM) is used to simulate the transient seepage of Beijiang Dike, and antiseepage solutions are designed and discussed. By comparing the measured data of a piezometer with the steady-state calculation model, the calculated results are compatible very well with the measured data. Aiming to improve the ability to respond in extreme weather conditions, we calculate the transient seepage field after the water level suddenly rises in a short time and then select the relief well as the antiseepage measure and optimize it. The results show that when the water level is 15.78 m, the slope reaches 0.5, and the embankment is damaged. With the increase of penetration depth, the effect of drainage and decompression in the depth of 3/5 and 4/5 is relatively small due to geological strips. Due to different geological conditions, the same relief wells are placed in different positions with a wide gap in effect, the antiseepage effect is the best when the horizontal distance is 95 m, and the effect is the best when the depth is 16.5 m. The research results can be used to guide the seepage prevention and control design of Beijiang Dike.

Relief Well Challenges and Solutions for Subsea Big-Bore Field Developments

Summary In subsea environments, using large-bore/high-rate well designs is often a key contributor to the economic recovery of hydrocarbon resources. Their use is a necessity for accommodating the huge production capacity of the reservoirs they penetrate, with the major benefit of minimizing the number of wells necessary to develop a subsea field. The enthusiasm for using such well designs, however, must also be tempered by a clear understanding of the considerable well control risk they introduce—that risk being an increased level of difficulty in bringing such a well under control if a blowout were to occur. It is common that multiple relief wells, with their inherent complexities and time investment, would be simultaneously required to bring a big-bore blowout under control. The discussion of this fact is, though, not a common topic in industry literature. Instead, capping stacks have been more the focus. Much recent attention has been trained on ensuring that capping stacks are a viable method for quickly responding to a high-rate subsea blowout. This makes sense in light of the simpler, and publicly more palatable, concept of rapidly installing a capping stack on a blown-out subsea well. Still, a capping stack is only as reliable as the wellhead it must connect to. It is because subsea wellheads have such a high chance of being damaged during a blowout that relief wells will always be relied on as the ultimate backstop for ensuring that a subsea blowout can be brought under control. This reliance on relief wells, as they are traditionally envisioned, has limitations though when addressing a high-rate subsea blowout. Any subsea relief well will have inherent limitations resulting from the architecture of choke and kill lines (flow restrictions) and that of the crossover piping at the blowout preventer (BOP; erosion concerns). In the world of high-rate subsea blowouts, these limitations can sometimes translate into multiple relief wells being required to inject fluid at the rates necessary to affect a dynamic kill. However, the simultaneous use of multiple subsea relief wells to dynamically kill a single blowout has only been tried once in the industry's history. As a result, some countries require that stopping a blowout must be possible by drilling only one relief well. In this paper, we describe methods that can be implemented to transcend traditional relief well limitations via using a relief well injection spool (RWIS), with the ultimate goal of dynamically killing a subsea big-bore blowout using a single relief well. The technique varies with water depth. In both shallow-water (826 ft) and deepwater (8,260 ft) environments, the techniques are presented and analyzed that will allow using a single subsea relief well to perform a dynamic kill using 15 lbm/gal drilling fluid injected at 238 bbl/min. This particularly severe scenario, based on a big-bore gas well development in Western Australia, is chosen so that our results will have applicability to most subsea well control events that might arise in the future.

Seepage Characteristics of a Single Ascending Relief Well Dewatering an Overlying Aquifer

The application of groundwater relief, i.e., dewatering, ascending wells, drilled upward from the mining tunnel into the overlying aquifer, is common in underground mining engineering. In this study, the seepage characteristics of single ascending partially and fully penetrating relief wells are investigated using a series of laboratory sand-tank experiments and numerical simulations. The seepage characteristics of ascending wells dewatering an overlying aquifer are different from those of conventional pumping wells descending from the ground surface into the underlying aquifer, because of the pronounced influence of the seepage face boundary condition along the seepage boundary of the ascending dewatering well. The seepage face of the ascending well is formed as the well casing remains open and water is discharged under the action of gravity through the well casing. The results of laboratory sand-tank experiments and modeling show that when the degree of penetration of an ascending relief well does not exceed a critical value, the effect of the seepage face cannot be ignored. In particular, the seepage flux increases as the degree of penetration increases following an exponential function, and the relationship between the seepage flux and the well radius can be described using a power law function. The results of numerical simulations are used to develop a series of type curves to evaluate the effects of the critical degree of penetration for different well radii and different aquifer water levels. Modified versions of the Dupuit and Dupuit–Thiem formulae for a single ascending partially well for the degree of penetration less than the critical one for the unconfined, confined, and confined-unconfined aquifers are developed.

A light piston well-flushing technique for clogged relief wells along Yangxin Dyke of Yangtze River in China

Plastic relief wells along Yangxin Dyke of Yangtze River in China have been seriously clogged in recent years. It is necessary to dredge the wells to restore its disaster prevention and mitigation function. However, traditional piston well-flushing technique is suitable to restore steel and iron wells, and it can cause damage to plastic relief wells. A new light piston well-flushing technique is proposed to overcome the limitation of traditional piston well-flushing technique. The proposed light piston has the advantages of simple structure, convenient use and low cost. By the light piston moving down and up quickly the relief well, the nylon brush can clean the side wall and filters of relief well, and the negative pressure can make the deposited materials in the aquifer and inverted filter sucked out. The proposed well-flushing technique is applied to restore the plastic wells along Yangxin Dyke of Yangtze River in China. Its efficiency is illustrated using field pumping test data. It is shown that the drainage capacity and permeability of clogged relief wells can be greatly improved after using the proposed technique. The light piston well-flushing technique can provide an effective way to restore clogged relief wells along Yangtze River levees.

Wellbore Positional Uncertainty and Correction of Directional Drilling

Wellbore surveying is the interactive process used to obtain wellbore positions according to well trajectory which connects surface coordinates to subsurface coordinates. The measured values such as the measured depth, inclination, and azimuth are used to calculate well paths with a specified reference system. However, errors exist between the true wellbore position and surveyed wellbore position, including depth measurement errors of the drillstring and wireline, misalignment errors, geomagnetic model, and magnetic interference errors. Therefore understanding and evaluating wellbore positional errors is critical for hitting reservoir targets, collision avoidance, and drilling relief wells. In this paper, wellbore positional uncertainty has been reviewed and the application of survey corrections in single and multiple wells has been investigated.