bluuebunny/crossref_metadata_2025 huggingface dataset:
A Novel Practical Approach to Borehole Breathing Investigation in Naturally Fractured Formations
Authors: Baldino S. , Miska S. Z. , Ozbayoglu E.
Published: February 2018

Occurrence of reversible mud losses and gains while drilling in naturally fractured formations is of primary concern. Borehole breathing can greatly complicate the already difficult practice of fingerprinting the changes in the return flow profile, hence undermining the reliability of kick detection. Issues can also derive from misdiagnosing a kick and attempting to kill a breathing well. The objective of this work is to correctly address the phenomenon and increase insights of its physical characterization. The fluid progressively flows in and out of fractures as a consequence of three mechanisms: (1) bulk volume deformation, (2) fluid compressibility, and (3) fracture aperture variation. To represent this complex scenario, a model involving a continuously distributed fracture network is developed. A time-dependent, one-dimensional dual-poroelastic approach is coupled with a variable fracture aperture and a passive porous phase. Finite fracture length is considered and no limitation on the number of fractures is posed. The latter permits us to analyze long open-hole sections intersecting several fissures, which is a more realistic approach than the available single fracture models. The proposed model is able to quantify pressure distribution in fractures and pores, together with the flow rate entering or exiting the fractures. When the fissured space is reduced to zero and incompressible bulk volume is considered, the solution reduces to that of classical reservoir engineering. A sensitivity analysis is performed on the physical properties of the formation and the drilling fluid. The latter provides a deeper insight on the factors that significantly influence breathing phenomena (i.e. drilling fluid weight, rheology and formation mechanical properties). Furthermore, a very useful application of the model is proposed by suggesting its application as a breathing discriminator during kick diagnosis. The shut-in drill pipe pressure, recorded from a real kick, has been compared to one caused by a simulated breathing case. Although the two SIDPPs show great similarities, the correct modelling of breathing can significantly help the identification of the major differences between a kick and breathing. Altogether, a comprehensive in-depth characterization of borehole breathing can help with kick diagnosis and can be used to effectively design unconventional drilling techniques such as Managed Pressure Drilling.
Optimizing Remote Operations Support Using an Effective Real-Time Model for Improved Drilling Performance
Authors: Robert Seth , Fiffick William , Davis Drew , Guillory Robert , Myers Joshua , Mandava Chakra
Published: February 2018

The wider use of robotics, remote controls, real-time remote monitoring systems, artificial intelligence, and other techniques are setting new standards of performance. The exciting culmination of these engineering and technological efforts have given us "The Rig of the Future".

However, how should we develop and manage the support systems to leverage this modern drilling technology? Do we have the people, processes, tools, and infrastructure needed to successfully apply these technologies?

The following case study reviews key elements necessary to support modern drilling, including: Real-Time Operations Centers, competent field service technicians, custom software applications, new processes and drilling performance technology. Properly applying these systems enhances drilling operations, ultimately leading to better drilling performance with decreasing non-productive time (NPT). The synergies between remote support, field operations, drilling technology, and other critical components are discussed in detail. This case study describes how the Real-Time Operations Center concept was conceived and developed. These support systems optimize field service performance by leveraging remote equipment condition monitoring, automating alerts, providing real-time rig data, and remotely interfacing key systems to improve the overall reliability of drilling operations.

As a result, many issues can be corrected remotely, decreasing average resolution times, resulting in better customer satisfaction ratings.

We discuss the necessary support processes, roles, and responsibilities. By leveraging the "Internet of Things", we achieve greater efficiencies. Augmenting the conventional roles for Field Service Technicians and other supporting functions adds additional value and efficiency. Working together, these distinct disciplines coordinate and mesh key responsibilities resulting in an "ecosystem" to support drilling operations.

While some struggle to provide systematic, comprehensive service and support models, a template of best practices has been developed and validated. This details remote operations centers, enhanced equipment technology, enhanced software applications, as well as enhanced employee development practices (for the necessary team of competent field service technicians). This model drives best-in-class drilling performance and is what "drilling rig of the future" looks like today.
Application of a New Dynamic Tubular Stress Model With Friction
Authors: Zwarich N. R. , McSpadden A. R. , Goodman M. A. , Trevisan R. , Mitchell R. F.
Published: February 2018

A new dynamic model for casing and tubing design with friction has been developed. This paper applies the model to a field case study, an actual installation of a single trip, multizone completion in an offshore highly deviated ERD well. This is the first application of a comprehensive model with complete friction history to both installation and in-service loads.

The field case demonstrates the results of a novel dynamic model for tubular stress and displacement with changing friction loads. Recorded hookload data during completion running and calibration of effective wellbore friction coefficients provided validation of the model. Accumulation of localized stresses at critical well locations is considered. The sensitivity of worst case downhole forces to the order of operational life cycle loads including stimulation, production and gas-lift was assessed. Stresses and displacements associated with each step of the setting process for multiple isolation packers were simulated. Theory and detailed description of the dynamic model are presented in an associated paper.

A dynamic model of tubing forces is necessary to predict local pipe velocity which in turn determines the magnitude and direction of the local friction vectors. Distribution and orientation of wellbore friction contact is determined by the pipe running events but then is subject to change as cement and packers are set and as downhole operating conditions change. Order of life cycle conditions such as stimulation followed by production versus production followed by workover has significant impact on the magnitude of forces at worst-case locations. The investigation included the change in tubing wellbore frictional contact when completion brine is displaced with dry injection gas in conversion to gas-lift. The model demonstrated the significance of a different order of linked operations and showed that the standard available analysis tools may overlook or fail to identify worst case loads. Potential for acute load localization due to successive stimulation and production events was quantified. Impact of migration of friction loads during cyclical load events was also evaluated. The predicted initial axial load profiles were verified with recorded hook loads and corroborated with standard torque and drag model results. Comparisons are made against a previously published analytical technique.

For the first time, a dynamic friction model enables seamless integration of running loads into a fully sequential analysis of subsequent well life cycle loads for landed strings. Current industry models tend to separate installation loads from the in-service life envelope. Ability to predict the changing friction orientation on installed tubulars is significant. Modelling life cycle loads in true sequence provides more accurate results for tubular design and enables a true analysis on the real-world order of well events.
Digitized Uncertainty Handling of Pore Pressure and Mud-Weight Window Ahead of Bit; Example North Sea
Authors: Lothe A. E. , Cerasi P.. , Bjørkevoll K. S. , Haavardstein S..
Published: February 2018

A digitized workflow from pre-drill pore pressure modelling with Monte-Carlo approach, till update of pressure prognosis while drilling from e.g. sonic and/or resistivity data is described. The innovative approach will reduce the uncertainty in the mud-weight window ahead of the bit.

For the 3D pressure modelling, a basin modelling software method is used, where the pressure compartments in the study area are defined by faults interpreted from seismic. Key input parameters like minimum horizontal stress, vertical stress and frictional coefficients for failure criteria are varied. The output is pressure profiles along the planned well path, with uncertainties.

The work presented in this paper was carried out on a North Sea dataset. The results show that the uncertainty in the pore pressures will highly influence the uncertainty span in both the fracture gradient and the collapse gradient. Representing the mud-window in terms of a most likely collapse and fracturing curve, with on each side of both, limits the minimum and maximum pore pressure derived limits, makes for a more realistic prediction, stating the uncertainty in the result.

While drilling, log-data will be automatically used to update the pressure and mud-weight prognosis ahead of bit. The digital updated prognosis can help the drilling crew in the decision-making during drilling campaigns.
Improved Methods to Understand and Mitigate Stick-Slip Torsional Vibrations
Authors: Bailey J. R. , Payette G. S. , Wang L.
Published: February 2018

In this paper, it will be shown how stick-slip vibration distributions can be used to evaluate drill string and parameter redesign options to mitigate stick-slip on the next well. It will also be shown how stick-slip vibration data can be used to estimate the time interval during which the bit is stuck when operating at or beyond full stick-slip.

The torsional vibration example to be discussed in this paper is based on the distribution of stick-slip vibration data when downhole data is available, or alternatively using surface torque swing data. The operator's frequency-domain dynamic model relates torque swing at the surface to the variation in bit rotary speed, as a function of the drill string design and surface RPM. Linear relationships between this distribution function and several variables are investigated, including the critical torque swing at full stick-slip, rotary speed (RPM), and downhole torque.

The operator drilled several wells in a vibrations-prone formation, and one well had extreme stick-slip vibrations whereas another well experienced minimal stick-slip as a result of limiter redesign. An understanding of the differences in the factors that led to the vibration reduction has been generalized into a procedure that can be applied to future wells. Although prediction of stick-slip in advance of drilling is difficult, with the benefit of data from one well it is possible to determine new parameters for a second well that will have significantly less stick-slip tendency.

In a well in a different field, high frequency torsional measurements at the bit provided data illustrating the rotary speed swing of the bit stick-slip cycle, highlighting the duration of time that the bit was in the stuck condition. Results from the dynamic drill string torsional model have been compared with downhole data, and application of the dynamic model and some new relationships enable stuck time to be related to the drilling parameters. The variation in stored potential energy on each stick-slip cycle can also be calculated.

These new understandings improve efforts to redesign relevant drilling parameters to mitigate stick-slip vibrations. Historically, prediction of stick-slip vibrations in advance of drilling has been fraught with challenges. Although we know what factors influence stick-slip, and what directional changes are required to mitigate this dysfunction, there is a need for a simple methodology to quantitatively determine the degree of dysfunction and the effects of one or more redesign parameters.
Automation Provides Unique Insights of The Rock Record and Subsurface Through the Delivery of a Robotic Sample Collection and Analysis Device
Authors: Tonner David , Swanson Aaron , Hollingshead Ron , Hughes Simon , Seacrest Stephen , McDaniel Bret , Leeper Jay
Published: February 2018

Objectives/Scope

From the very early days of oil and gas exploration, appraisal and development drilling, samples have been collected at the rig by mud logging personnel to conduct a preliminary geological analysis of the rock being drilled. This collection typically involves a sample collection recipient, board or bucket to collect a sample of rock over the desired interval. The sample is then sieved and cleaned in the appropriate way depending on the type of drilling fluid being used. As penetration rates have increased in some instances to more than 400 ft. / hr. the sample resolution has deteriorated exponentially. From an ergonomics perspective, the highest frequency to which a person onsite can collect a sample is once every 20 minutes. At 300 ft. / hr. this translates to 100 ft. of drilled rock. A new device has been developed and deployed which automates this manual process and thus ensures faster and more accurate collection of geological samples of the drilled rock interval. Sample resolutions of 5ft rock intervals have been attained at 400 ft./ hr. This technology has provided an important technological breakthrough and enables reduction of personnel at the rig site with a subsequent reduction in cost and HSE risk, particularly in areas of H2S. It further has provided for the potential integration with Measurement while drilling personnel. For both conventional and unconventional play development, this has provided oil and gas operators with an important and cost and risk reducing modus operandi compared to conventional drilling and evaluation techniques. The tool was deployed for an operator in West Texas where both manually collected traditional mudlog samples and automatically collected samples were taken. The samples were analyzed and compared for rock content. In addition, comparisons were made between point sampling with the automated system versus samples collected over a defined interval manually. Results of these comparisons will be presented.

Results, Observations, Conclusions

A new method of automated drill cuttings sample collection has been successfully deployed. The new method provides a step change improvement in accuracy and resolution for sampling the rock record during drilling.

Novel/Additive Information

Additional data of the rock record provides potential insights to optimize wellbore placement and provide increased geo-mechanical data to optimize completions.
Application of an Innovative Spacer System Designed for Optimal Performance in HTHP Wells
Authors: Doan Angela , Holley Andrew , Kellum Matthew , Dighe Shailesh , Arceneaux Cory , Conrad Ken
Published: February 2018

Extreme well conditions, especially higher temperatures, are becoming more commonplace. This in turn requires improvements to our wellbore fluids. This study focuses on the development of a new spacer system designed especially for those wells exhibiting extremely high temperatures.

A critical characteristic of this spacer is that the surface rheology must not be overly excessive as to maintain a pumpable fluid; however, the downhole rheology must not diminish due to thermal thinning or degradation of the gelling agent so the spacer remains stable. To ensure the spacer suitably meets these requirements, both ambient and elevated temperature rheologies are analyzed and reported. The stability of the spacer related to settling of solid particulates is examined by conducting dynamic settling tests at 300°F and above.

In this study, spacer compositions and densities were adjusted to examine effects on rheology and stability of the solids within the system at elevated temperatures. Results show that conventional spacer systems are not adequate at elevated temperatures especially above 300°F. The newly developed spacer system shows much improved results from dynamic settling tests even up to 400°F. Also, the surface rheology of the new spacer system is not significantly different from that of the conventional system.

The innovative spacer system within this paper was shown to add significant value to extreme cementing operations. In addition, by comparing the results between these two testing methods, the dynamic settling test should be considered as an alternate procedure for testing the stability of spacers under high temperature conditions.
Measuring Land Drilling Performance
Authors: Willis John B. , Jackson Richard
Published: February 2018

Managers seek understanding of drilling performance, and visibility of how groups contribute to drilling results. The process described improves executive's understanding of drilling cost and performance. The principles are applicable to any drilling program (and even other, non-drilling operations), but are best suited to land drilling programs with many wells of common types.

In this method, a baseline budget is established for each type of well. As the program changes, a revised budget is created based on the wells actually drilled, plus those currently planned. The monthly revised budget measures performance against a consistent benchmark. The definition of well types, tracking of costs, adjusting for unusual situations, and calculations to apply the technique are discussed. The revised-budget process is used with traditional operational metrics to provide a complete spectrum of performance metrics for all levels of the organization.

The revised-budget method provides a clear perspective of performance, more insightful than standard "actual vs budget" comparisons. Additionally, deviations from benchmarks are quantified by performance, pricing, and scope changes. These categories correspond to organization groups that contribute to performance. The use of the revised-budget technique focuses discussion on the correct issues (performance, pricing, and scope) for each group. Historically, discussion of cost deviations often bogged in debate over which group was responsible. With this system, the contribution of each group to results is identified.

The revised-budget technique does not replace, but enhances traditional drilling metrics such as cost-per-foot, feet-per-day, flat time, non-productive time, and others. Traditional analysis methods are of most value to drilling groups in seeking specific actions to improve.

The system is the result of 10 years of evolution of measures to manage drilling more than 16,000 wells globally. The system has delivered best-in-class performance.

The novel aspect is that it is a complete system encompassing a workable benchmark, it adapts to the constant changes in the drilling program, it identifies how groups contribute to results, and it connects to traditional drilling metrics. The revised-budget technique using granular benchmarks is applicable to many types of operations and solves a chronic budget review problem.
The Application of Wellbore Strengthening to Achieve Zonal Isolation
Authors: Majidi Reza , Dondale Aaron , Braley Nicholas , Flores Rafael
Published: February 2018

Lost circulation while running casing, pre-cement job mud circulation, and cement placement can result in additional remediation, create challenges in achieving zonal isolation objectives, and potentially impact well integrity. Several mitigation methods are available to address lost circulation challenges. However, the focus of this article is on prevention.

Wellbore strengthening is utilized to strengthen low fracture gradient (FG) and permeable zones to a target maximum equivalent mud weight (EMW) value induced during tripping, circulating, or cementing. Engineered wellbore strengthening pills of specific particle concentration and size distribution are placed in the open hole and pressure is applied to the wellbore in a controlled fashion. As a result, a higher fracture gradient of the weak sands exposed in the entire interval is achieved, allowing permeable formations to withstand higher EMW during subsequent tripping, circulating, and cementing operations without inducing losses. This paper summarizes the field application of wellbore strengthening in deep-water Gulf of Mexico (GoM) to achieve zonal isolation. The design, execution, and post-well analysis of several wellbore strengthening applications in a variety of sands from shallow and soft overburden sands to deep producing reservoir sands with depletions greater than 4,000 psi, are discussed. A detailed case study for one of the wells is provided.

The track record of successful wellbore strengthening treatments performed demonstrates the potential for achieving adequate annular cement placement and zonal isolation in narrow pore pressure fracture gradient environments.
Tubular Ratings Used in Well Containment Screening Tool
Authors: Rahman Shaikh , Mason Stan , Sathuvalli Udaya B. , Lumley Pete
Published: February 2018

One of the documents that a drilling operator must submit with the Application for Permit to Drill (APD) to the Bureau of Safety and Environmental Enforcement (BSEE) is the Well Containment Screening Tool (WCST). The data are submitted via eWell by the operator during the APD process. The results of the screening tool are used to demonstrate that the well is adequately designed to contain uncontrolled flow. Worst Case Discharge (WCD) loads are considered as survival loads, and the exposed tubulars must satisfy a design factor is 1.0, for both burst and collapse loads. Two levels of screening are performed in the WCST. Level 1 screening assumes BSEE specified hydrocarbon gradients and ensures that the well can be fully shut-in without causing underground flow. If the well fails Level 1 screening, or if the well contains an unconditionally trapped annulus, Level 2 screening is required to ensure well integrity during unrestricted flow, and subsequent full shut-in. In both levels, the mechanical integrity of the tubulars is one of the three categories that the WCST does screen. BSEE does not provide guidelines on what tubular ratings should be used to account for the effects of downhole temperature. Using manufacturer provided ratings will be less than conservative, since they are valid at room temperature. The burst rating should be derated for the temperature at the depth of interest, because yield strength decreases with temperature increase. The collapse rating should be derated not only for the temperature, but also for the axial tension, if it exists, at the depth of interest for the WCD load. The temperature derated burst and collapse ratings can be estimated when expected WCD temperature is known. The tension derated collapse rating requires a complete examination of the load. The current version of the WCST does not facilitate this task; and the results can lead to a potentially non-conservative conclusion. This paper discusses the impact of temperature and tension on WCD loads and how to use the WCST more accurately.
Automated Directional Drilling Software and Remote Operations Centers Drive Rig Fleet Well Delivery Improvement
Authors: Gillan Colin , Isbell Matt , Visitew Travis
Published: February 2018

Early in 2017, initial discussions began to define an Automated Remote Drilling project that would use a centralized command center and specialized distributed software systems to automate the directional drilling decision-making workflow and the implementation of these decisions at the rigsite. The objective of this de-manning of directional resources at the rigsite was to enable the Operator's in-house directional supervisors to efficiently and safely control a larger number of rigs than was previously possible with legacy work practices and software.

In addition to the standard high-speed data links from office to rig, the project was based on an automated directional software guidance system configured to optimize directional motor slide drilling. This integrated directional navigation software suite also communicates directly with the top drive directional control system to ensure slide commands are implemented exactly as calculated. The software suite captures and assesses the effectiveness of slides automatically and uses sophisticated steering logic and steering targeting systems to support directional drilling best practices and geo-steering adjustments in the production zone.

The paper presents aggregated feedback from directional drillers on the automated systems' decisions and the results of following system directives in the low angle and nudge sections, in the curve, and in the lateral wellbore. Case studies are presented, along with summaries of the workflow changes implemented in town and at the rigsite. Several current lateral Bakken wells are presented as evidence of the effectiveness of the Automated Remote Drilling project approach and the benefits of this level of collaboration between a forward-looking Operator and drilling contractor.

The combination of the directional navigation software, the automated implementation, the geo-steering support, and a new Automation Assisted Workflow presents a new approach to an industry-wide challenge in the current market of how to do more with less without compromising efficiency, safety, or intervention capabilities.
Self-Learning Probabilistic Detection and Alerting of Drillstring Washout and Pump Failure Incidents During Drilling Operations
Authors: Ambrus A. , Ashok P. , Ramos D. , Chintapalli A. , Susich A. , Thetford T. , Nelson B. , Shahri M. , McNab J. , Behounek M.
Published: February 2018

The mechanical failure of drilling equipment is an operational risk that can be limited through a robust detection and alerting system, particularly for Drill String Washouts (DSW) and Mud Pump Failures (MPF). The detection of these issues focuses primarily on the time signatures of the real-time and modeled pump pressure in relation to the flow rate trends. Together, these parameters describe the state of the equipment which can be assessed through real-time alerts.

A new methodology for real-time detection of washout and pump failure incidents during drilling operations was developed. The methodology behind the detection system uses a Bayesian network that models the drilling hydraulics and their associated failure modes. The network aggregates data from real-time rig floor sensors (standpipe pressure, pump rate, flow out, etc.), contextual information (rig state, mud properties, etc.), and predictions from hydraulic modeling. Cumulatively, they are the determinants of a probabilistic belief system indicative of DSW and MPF. The probabilistic model outputs belief values for DSW and MPF between zero and one. Given past and present trends, the model increases accuracy though self-learning and self-calibration that adjusts for poor sensor data, drilling conditions, and model uncertainty.

The Bayesian network was integrated into decision support software with real-time alerting capabilities. The software was then validated by an operator's 100+ onshore wells in North America, some of which contained MPF and DSW incidents with varying degrees of severity. Several case studies drawn from these wells are presented in the paper.

Each failure event that exceeded a programmed threshold for a specified period of time generated an alert in the form of a PDF report containing real-time sensor traces and DSW and MPF prediction outputs. The alerts were also displayed on a dashboard on the rig site user interface. Software thresholds were optimized to reduce false alert reports presented to the driller. Through continuous improvement and validation, DSW and MPF detection reached a level of accuracy which, in some cases, detected the warning signs of a failure hours before the problem was noticed at the rig site. Conclusively, the value added by the early detection of mechanical failures is the decreased amount of non-productive time due to pump downtime and maintenance, as well as trips and fishing jobs due to washed out pipe.
A New Rotary-Steerable System Designed for Vertical and Nudge Applications in North America Pad Development Drilling
Authors: Jones Steve , Sugiura Junichi , Feddema Chad , Charter Marc
Published: February 2018

Pad drilling has become commonplace for North America shale development drilling, which requires tighter well spacing/separation and reduced anti-collision risk. A new digitally-controlled rotary-steerable system (RSS), extensively embedded with electronics, solid-state sensors and electrically controlled mud valve, has been developed specifically for drilling vertical and nudge well profiles from pads in North America. Unique technology includes a slow-rotating steering housing with four mud activated pads to apply side force at the bit. The pad activation is controlled using a novel mud valve driven by a low-power electric motor and gearing system. Activation of the steering pads and control of force to the steering pads is achieved using a small percentage of mud flow and approximately 500 psi pressure drop below the tool. The limited amount of mud flow passing through the mud valve eliminates internal wash issues and reduces repair costs.

The electronics measurement and control system are mounted in the slow-rotating steering housing and includes 3-axis inclinometers, 3-axis magnetometers, 3-axis shock sensors, 3-axis gyros, and temperature sensors. Additionally, compact drilling dynamics sensors are placed at the bit box to gather at-bit data to evaluate bit-rock dynamic interaction.

This paper will describe the unique features that allow the system to be reliable and cost-effective for high-volume land drilling activities. The RSS bottom-hole assemblies (BHAs) have been extensively instrumented with multiple downhole dynamics sensors, which reveal a challenging drilling environment unique to vertical drilling and nudge applications and show the performance of the RSS in this environment.
Drilling as an Evaluation Tool in Horizontal Shale Wells
Authors: Mace Jason
Published: February 2018

The development of unconventional resource plays in the United States has led to numerous changes in the fields of drilling engineering and reservoir evaluation. During the initial years of high commodity prices, the act of drilling a horizontal shale well became more of a service and less of a science in an effort to increase speed of development. Reservoir evaluation through logging suites and core analysis was cast as an unnecessary cost and shale reservoirs were deemed to be "statistical plays"1. Recent downward force on commodity prices has threatened the viability of many active fields and pushed operators into developing only core acreage in an effort to sustain positive well economics.

This new "lower for longer" pricing environment has spurred ingenuity in an effort to elevate non-core acreage to core acreage status and enhance well productivity. Operators have shifted their views on reservoir evaluation by running logging while drilling (LWD) tools behind the bit, logging through the bit on wiper trips, or cased-hole logs such as a pulsed neutron and dipole sonic. Of interest in this paper is the use of drilling data as an analog for conventional logging suites, which add time, cost, and risk to well operations. By applying mechanical specific energy (MSE) data generated from the penetration of the formation, drilling engineers can turn an often disregarded data set into both cost savings and enhanced well productivity.
Integrated Analytical Trajectory Control Model
Authors: Gomez Carolina , Nunez Carlos , Samuel Robello
Published: February 2018

Typical trajectory-monitoring models only consider the geometrical approach, without considering the rock mechanics and operational constraints in a single algorithm. Trajectory corrections could compromise the wellbore stability and drilling efficiency. For this reason, an integrated analytical model is needed to couple the trajectory-control model with the rock mechanics and mechanical, rotational and hydraulic effects in the trajectory correction. This integrated approach allows to visualize the "big picture" when returning to the designed well path.

The paper provides a roadmap so that the directional driller can use in the field in real-time. The geomechanics validation ensures that the wellbore stability is not compromised so that the correction results in trouble-free drilling. The HMSE evaluation enables to analyze the drilling efficiency in terms of mechanical, rotational and hydraulic energy to identify dysfunctions and other operational causes and effects on the trajectory. To validate the integrated model different deviation scenarios are simulated using the information of real wells already drilled. The results have proven that the smoothest correction path calculated is not always the best path as it may result in operational problems. The use of this integrated model allows to anticipate and mitigate operational problems which translate in improved drilling efficiency. This paper aims to bridge this existing knowledge gap and provides a comprehensive treatise on well trajectory control and, more in general, estimations and their underlying model parameters. The paper describes the details and the new calculation methodology of coupling these various models. The paper presents specific field examples with and without these models where there were wellbore stability problems.
Measurement of Dynamics Phenomena in Downhole Tools - Requirements, Theory and Interpretation
Authors: Hohl Andreas , Herbig Christian , Arevalo Pedro , Reckmann Hanno , Macpherson John
Published: February 2018

Downhole tools in bottom-hole assemblies are subject to high dynamic loads during drilling operations. The negative impacts of these dynamic loads can be inefficient drilling with low rate of penetration (ROP), reduced downhole directional and formation measurement service quality, and downhole tool failures with associated non-productive time.

The dynamic phenomena can be categorized by direction into axial, torsional and lateral vibrations, and by excitation mechanism into forced excitation, self-excitation, and parameter excitation. Forced vibrations are mainly caused by imbalances in the drilling system or by the working principles of downhole tools such as the mud motor. Self-excitation mechanisms are mostly driven by the interaction of the bit, reamer or drilling system with the formation, and can cause detrimental dynamic behavior such as torsional stick-slip, bit bounce, and backward whirl.

These diverse vibration phenomena require tailored mitigation strategies. To a certain extent, these mitigation strategies are contradictory. Misinterpretation of downhole measurements can lead to even worse vibration levels with severe consequences for reliability, ROP, and measurement quality.

As a consequence, downhole measurement devices should differentiate vibration phenomena. This distinct differentiation could then be used to choose appropriate mitigation strategies.

This paper analyses and defines the requirements for dynamics measurement devices. The specification, number, and placement of sensors and their associated sampling rates are examined to distinguish vibration directions and phenomena. The usefulness of these requirements is demonstrated using examples of torsional stick-slip and high-frequency torsional oscillations, lateral vibrations, and backward whirl. The results of kinematic modeling are analyzed and compared to high-speed vibration data from field runs measured with the latest generation of vibration measurement tools. Possible misinterpretation of vibration conditions in the case of inappropriate measurements is shown. The results are discussed by comparing theoretical modeling with field data.

The defined requirements and guidelines enable a flawless interpretation of downhole vibration measurements and unveil drilling optimization opportunities. Different vibration phenomena can be identified reliably and appropriate mitigation strategies applied in real time at the wellsite by the driller or automation systems. This finally reduces the vibration load on the drilling system, increasing its reliability and performance.
Dilatancy and Pressure Dependence of Threaded Connection Performance
Authors: Mitchell R. F. , Goodman M. A.
Published: February 2018

Connector joint strength and leak resistance depend on internal and external pressures. Axial tension or compression opens (dilates) the connector, while the pressures close the connector. This paper presents a "toy connector" model that incorporates actual connector elements, but in a simplified form useful for analysis, so equations of joint strength and leak resistance can be determined as functions of axial load and internal/external pressures. The model and example case in this paper confirm that dilatancy occurs and hydrostatic pressure plays a critical role in connector failure (leak, pull-out, or thread shear). Von Mises stress alone cannot model dilatancy and the hydrostatic effect.
Teraphtal (sodium salt of cobalt 4,5-carboxyphthalocyanine) Decreases Sensitivity of Tumor Cells to Anthracycline Antibiotics and Mitoxantrone in Vitro
Authors: Sidorova Tat'yana Aleksandrovna , Ryabaya O.O. , Tatarskii V.V. , Khochenkov D.A. , Ivanova E.S. , Kaliya O.L.
Published: February 2018

Background. Anthracycline antibiotics (AA) are widely used in clinical oncohematology. As is well known АА cytotoxicity diminishes in the presence of hemin (FePPIX), an endogenous metalloporphyrine. Aim. To study effect of teraphtal (TPh) and its structural analog FePPIX on cytotoxicity of “anthraquinone” drugs AA and mitoxantrone (MiTOX) in vitro. Materials & Methods. The study was performed using human leukemia cells of K562 line and HCT 116 adenocarcinoma cell line. TPh ability to prevent AA-induced tumor cell death has been estimated by the following methods: MTT assays, flow cytometry, light microscopy, cytochemical method for determination of ß-galactosidase expression using X-Gal substrate, DNA electrophoresis, LDH release, real time RT-PCR, and radiometric method. Results. In the presence of TPh (10 pM) the AA and MiTOX cytotoxicity diminishes approximately 4- and 20-fold respectively. The TPh protective potency is dependent on the AA chemical structure. In the presence of TPh aclarubicin toxicity remains constant. The TPh/FePPIX protection from the AA cytotoxicity can involve the same mechanism reducing the ability of the cells, including the leukemia tumor cells, to accumulate AA in the presence of modulators. TPh/FePPIX protects human tumor cells from AA-induced death, such as apoptosis, necrosis, and accelerated senescence (AS). АS in K562 leukemia cell line induced by AA + TPh/FePPIX results in cell-suspension-derived-small-cell colonies. Вес/іп-lysosomal pathway of autophagy is not engaged in reducing of the AA toxicity of K562 cells in the presence of TPh. Conclusion. Reducing of the AA toxicity and revival of population growth in the presence of TPh/FePPIX should be taken into consideration when using hematoporphyrins and phthalocyanines having a structure similar to TPh as sensitizers in the chemotherapy protocols.
Ibrutinib in the Treatment of Relapsed Chronic Lymphocytic Leukemia
Authors: Stadnik Elena Aleksandrovna , Timofeeva N.S. , Strugov V.V. , Zaritskii A.Yu.
Published: February 2018

Aim. To estimate ibrutinib efficacy in the treatment of early CLL relapses and in patients with > 2 lines of preceding therapy. Analysis of treatment results in patients with del(17p) and monitoring of minimal residual disease (MRD) and ibrutinib safety profile. Materials & Methods. The analysis included the results of ibrutinib treatment in 31 patients with CLL. Twenty eight patients were treated by bendamustine and fludarabine containing regimens. The median prior treatment lines were 2 (range 1-10). The indications for the treatment initiation were the first early relapse in 51 % of cases (n = 16) and a relapse after 2 and more lines of therapy in 49 % of cases (n = 15). Ibrutinib was administered in mono- (n = 15) and combined therapy (n = 14) as well as in the R-BAC scheme (n = 2). Using FISH analysis del(17p) was found in 9 patients (34 %). Results. Within the median follow up of 18 months (range 7-42+) the overall survival (OS) rate was reported to be 87 %, and the progression-free survival (PFS) rate was 77 %. The maximum MRD after a year of ibrutinib treatment was observed in case of combination with immunochemother-apy (e.g., R-BAC). Within the period of 18 months OS rate was 100 %, in the patient group with early relapses and 66 % in the group with a relapse after 2 and more therapy lines (p = 0.02). Within the same examination period PFS was significantly higher (94 %) in the patient group with early relapses compared to the previously treated patients (60 %) (p = 0.034). The most common adverse events were grade 1-2 purpura (30 %), grade 1-2 diarrhea (10 %), atrial fibrillation paroxysms (10 %) and arterial hypertension (10 %). Severe infectious complications registered in 6 % (n = 3) patients were successfully solved in the course of combined antibacterial and antimycotic treatment. Conclusion. Ibrutinib was shown to be effective drug for treatment of relapsed CLL. The OS and PFS values were more favourable in patients with early relapses compared to the patients with relapses after > 2 lines of therapy prior to ibrutinib treatment. The maximum elimination of the tumor clone was observed after combined ibrutinib/immunochemotherapy treatment. The tolerance of ibrutinib was reported to be satisfactory with acceptable toxicity profile. No mortality due to infection complications was observed.
The Use of Brentuximab Vedotin in Relapsed/Refractory Hodgkin’s Lymphoma in the Kransnodar Region
Authors: Serdyuk Ol'ga Dmitrievna , Yaskul'skii D.A.
Published: February 2018

The treatment of relapsed/refractory Hodgkin’s lymphoma (HL) remains to be a challenging issue. The morbidity of HL is reported to increase in the Krasnodar region. While considerable progress in the treatment of HL has been achieved, the relapse rate still remains high. The standard second-line treatment allows for the disease control in only half of cases of relapsed HL. Until recently, however, relapses after autologous hematopoietic stem cell transplantation (autoHSCT) could be treated only by polychemotherapy aimed at slowing the tumor growth. The use of anti-CD30 conjugated monoclonal antibodies and cytotoxic agent was shown to control the relapsed disease after high dose chemotherapy followed by autoHSCT. The present study provides pharmacological characteristics of brentuximab vedotin, its antineoplastic mechanism as well as the author’s own clinical experience in the management of a female patient with HL after autoHSCT.
Prognostic Value of Genetic Markers for Efficacy Estimation of Induction Treatment Including Autologous Hematopoietic Stem Cell Transplantation in Multiple Myeloma Patients
Authors: Nazarova Elena L'vovna , Minaeva N.V. , Khorobrykh M.N. , Sukhorukova E.E. , Shardakov V.I. , Paramonov I.V. , Zorina N.A.
Published: February 2018

Aim. To determine the value of polymorphisms of the immune response genes for the treatment efficacy in MM patients receiving high-dose chemotherapy and autologous hematopoietic stem cell transplantation (autoHSCT). Methods. The overall of 20 ММ patients (8 men and 12 women) were included in the study. The median age was 51.5 years (range 32-67). Clinical laboratory tests had been performed before melphalan high-dose (200 mg/m2) conditioning therapy. In accordance with the achieved anticancer response to induction treatment the patients were divided into 3 groups: patients with partial remission (group 1; n = 7); patients with very good partial remission (group 2; n = 9); patients with complete remission (group 3; n = 4). Genotyping of 20 polymorphic loci of 14 immune response genes was performed using PCR. Results. The study showed that group 2 had no AA mutant homozygotes of IL10 in the G-1082A polymorphic locus compared to group 3 and no TT mutant homozygotes of TLR6 (Ser249Pro) compared to group 1. The patients with more pronounced mucositis (grade 2/3) compared to patients with minor mucositis (grade 0/1) had no CC mutant homozygotes of IL1ß in the G-1473C position and a smaller number of (CT+TT) heterozygous and homozygous haplotype carriers of IL10 with the T mutant allele in the C-819T mutation point. The multivariate analysis showed that the genetic marker statistically effecting the progression-free survival rates in MM patients after high-dose chemotherapy and autoHSCT was the polymorphous status of the IL10 (G-1082A), TNF (G-308A), TLR4 (Thr399Ile), and TLR9 in the T-1237C and A2848 polymorphic loci. Progression-free survival rates correlated with the mutation status of IL1ß (T-511C), IL2 (T-330G), IL6 (C-174G), CD14 (C-159T), TLR3 (Phe421Leu), and TLR4 (Asp299Gly). Conclusion. The obtained data show the correlation of 14 polymorphisms of 10 immune response genes with the immediate results of the induction treatment, and also with the severity of mucositis during the early post-transplant period, as well as overall and progression-free survival rates in MM patients. Due to a small sample volume further studies will be planned with the aim to verify the identified trends. The suggested hypothesis for immune response gene polymorphism effecting a disease prognosis can substantially contribute to developing of individualized approach to MM treatment.
Conventional and Conformai Radiotherapy with and without Beam Intensity Modulation in Patients with Stage II Hodgkin's Lymphoma with Supradiaphragmal Lesions
Authors: Vinogradova Yu.N. , Ivanova E.I. , Chumachenko A.I. , Smirnova E.V. , Andreev G.I. , Kalesnik A.M. , Vorob'ev N.A. , Il'in Nikolai Vasil'evich
Published: February 2018

Within the group treated with the conventional RT 19 (8.1 %) patients had recurrent disease. Overall 5- and 10-year survival (OS) was equal and accounted for 98.0 ± 1.4 %, the disease-free survival (DFS) was also equal between groups and accounted for 85.9 ± 1.3 %. The rate of 5- and 10-year OS in patients who received CF was 97.8 ± 1.7 %; the DFS rate for the same period was 85.0 ± 1.5 % with standard fractionation and 86.2 ± 1.6 % with MF (p > 0.1). The total number of local radiation reactions and the number of radiation pulmonitis were significantly smaller with the exposure twice daily compared to CF at 2D planning and mantle irradiation. Decreasing the radiation volume from the mantle type to IFRT was shown to reduce the incidence of pulmonitis. The incidence of esophagitis remained the same with different fractionation and the irradiation volumes specified above. The results of the analysis proved the total absence of radiation pericarditis with both types of conformal RT with or without IMRT. No pulmonitis cases were observed with IMRT; the use of 3D-CRT and 2D-RT significantly increased the incidence of pulmonitis. The incidence of esophagitis within the CRT-group (n = 80) was 2 times lower compared to the conventional RT (22.5 % and 43.9 %; p < 0.01). Conclusion. The innovative technologies of radiation therapy allowed to reduce the incidence of early local radiation reactions. These technologies will be the basis for preventing severe late radiation complications that reduce the life expectancy and quality of life of patients with HL.