bluuebunny/crossref_metadata_2025_split huggingface dataset:
While-Drilling Pore Pressure Surveillance Using Machine Learning
Authors: Raman Rahul , Spivey Benjamin , Fink Richard , Karner Stephen 
Published: March 2023

Abstract
While-drilling pore pressure surveillance enables timely responses to unexpected drilling events, e.g., wellbore instability, or to pressure changes that could impact mud weight requirements or casing depths. The real-time pressure surveillance and analytics (RT-PSA) system described herein aids while-drilling pressure surveillance by highlighting possible pressure trends and detecting pumps-off gas automatically. The system further assists pressure surveillance practitioners by automatically filtering for lithology and providing a visualization dashboard to highlight possible pressure trends.
The pressure trending application calculates slopes/trends for LWD and mechanical data and uses these trends to indicate possible pressure trends along the well path using a heat map. A lithology filtering method has been developed using machine learning (ML) clustering algorithms to remove non-shale data, leaving only clay-rich shale lithology for pressure trending.
The gas monitoring application aligns the gas curves back to the time and depth at which gas is liberated from the formation by the drill bit, called herein as at-the-bit curves. The application displays modified total gas, gas exponent, and gas ratio curves as at-the-bit curves. The gamma ray and resistivity LWD logs are also shifted back to the time/depth that the bit drilled the measured formations. Aligning the gas and formation log curves to be at-the-bit provides the pressure surveillance personnel with additional context beyond traditional gas surveillance data to classify gas measured at the surface as pumps-off-gas or formation gas.
Results demonstrate that the lithology filtering method using machine learning is effective to filter out clay-rich shale. The pressure trending results are consistent with post-drill pore pressure evaluations generated by pressure prediction experts. The shifted total gas and pumps-off gas have been validated versus post-drill pressure analysis. The system is being deployed to mitigate well control events by improving and standardizing pressure surveillance best-practices across a global organization.
Drilling Dysfunction Demystified Using In-Bit Strain Sensors
Authors: Witt-Doerring Ysabel , Pastusek Paul , Lacey Aaron , Barajas Pablo , Bergeron Michael , Clayton David , Sowers Steven 
Published: March 2023

Abstract
Drilling dysfunction causes premature failure of bits and motors in hard formations. Dysfunctions may be influenced by; bit design, bottom hole assembly (BHA) design, rig control systems, connection practices, and rotating head use. Sensors that record weight, torque, and vibration in the bit can offer insights that are not detectable further up the BHA. By understanding the root causes before the next bit run, it is possible to rapidly improve performance and prolong bit life.
The formation being drilled in this study is a hard extremely abrasive shale, requiring 35+ runs per lateral section. The primary cause of polycrystalline diamond cutter (PDC) failure was smooth wear and thermal damage. The wear flats are attributed to abrasion and mechanical chipping that rapidly progress to thermal damage. Higher weights were not effective and it was hypothesized that buckling was occurring, causing insufficient weight transfer and increased lateral vibration. In-bit sensors that measure weight, torque, revolutions per minute (RPM), and lateral, axial and torsional vibration were run in hole to evaluate the weight transfer issues and dysfunction.
High frequency downhole and surface data were combined with forensic images of the bit and BHA to confirm the weight transfer issues. In total, three major problems were identified and rectified during this study: drill string buckling, rate of penetration (ROP) loss due to the use of rotating control devices (RCDs) and WOB and differential pressure (DIFP) tare inconsistencies.
Drill string buckling resulted in the downhole WOB being much less than surface WOB (DWOB&lt;&lt;SWOB) in early runs. Heavy weight drill pipe (HWDP) was run across the buckling zone to correct this. Subsequent runs showed a significant improvement in DWOB, reduction in lateral bit vibration, and improved performance and dull condition.
Significant decreases in DWOB, DIFP, and ROP were noted when running tool joints through the RCD. Although observed before, in-bit accelerometers showed an increased lateral vibration that was a result of the loss in ROP and this continued long after the ROP recovered.
DWOB and downhole torque (DTOR) were often much higher than SWOB and DIFP (converted to torque). Plots of hookload and stand pipe pressure tare values were used as indicators of inconsistent tares. Although premature motor failure were not noted in these runs, premature PDC cutter failure were.
High frequency in-bit load sensing was used to identify persistent lateral vibration after a ROP loss event due to tool joints interacting with RCDs. A team based, continuous improvement, process was used to evaluate the root cause of downhole dysfunction and recommend bit/BHA design and operating procedure changes before the next bit was on bottom. This rapid analysis and joint recommendation process significantly prolonged bit life and improved drilling performance.
Facts, Fallacies and Pitfalls of Using Mechanical Specific Energy (MSE) – Part 1
Authors: Samuel Robello , Mensa-Wilmot Graham 
Published: March 2023

Abstract
Over the years, some researchers have used Mechanical Specific Energy (MSE), which is said to represent the amount of energy needed to drill a unit volume of rock, to quantify drilling efficiency. MSE was originally introduced by Teal for the mining industry in 1964. Since then, MSE has taken different forms for other reasons, based on its interpretation, and intended use. This paper provides a comprehensive review of MSE in general, discusses its different forms and narratives, and draws the readers' attention to common (and not so common) facts, pitfalls, and fallacies, of using MSE.
It has been found that these specific energy concepts are held as true for all predictive purposes in drilling, amended and promoted beyond the original framework. The paper analyzes all the equations presented in the past and quantifies each component of the equations. The hydraulic terms used alongside the mechanical terms are also discussed. Extensive simulations have been carried out and will be reviewed in this paper by quantifying the energy under each term based on rate of penetration effects and implications. We aimed to demonstrate in this paper, the theoretical grounds for pitfalls and fallacies in using MSE.
MSE is made up of two components: torsional energy and thrust energy. The results have shown that the thrust term is much smaller than the second torsional energy term and in most of the cases, about 2% or less. Hence, it could be neglected and thereby the equation results in the form of inverse of the rate of penetration (ROP) making the calculated MSE value redundant when the actual ROP is available. The results also have shown that when the hydraulic energy term is subtracted from the MSE equation, it results in negative rate of penetration and thereby shows a fundamental flaw in the system formulation. The purposed and merits of MSE use, by some researchers to identify drilling dysfunctions, will also be highlighted. In this process, it has been shown that nonlinear "torque wedging" causes inaccuracies in dysfunctions identification and discussions. Also, the field data presented in the paper shows that mechanical energy is not a ratio of input energy and rate of penetration. Moreover, none of the studies have accounted accurately for the effects of bit wear and motor wear on MSE. It has been found that overall, the concept relating to dysfunction quantification is a self-destructive process, which has spread from paper to paper without the required checks and verifications for accuracy. The underpinning discussions have been backed and demonstrated with numerical examples.
The paper provides the pitfalls in the omissions of some of the assumptions in various MSE models used by engineers. This helps the users to carefully plan, design, engineer and construct the wells.
Towards the Correct Interpretation of Real-Time Signals on the Well-Site
Authors: Daireaux Benoit , Brackel Hans-Uwe , Ewald Robert , Markussen Petter , Johansen Maria , Parak Mahdi , Yadav Ghanshyam , Ismayilov Anar 
Published: March 2023

Abstract

Objectives/Scope
Drilling operations rely on the collaboration of many participants, and the efficiency of this collaboration depends on timely exchange of information. The complexity and variability of this information make it difficult to achieve interoperability between the involved systems. Recent industry efforts aim at facilitating the many aspects of interoperability. A central element is semantic interoperability: the ability to correctly interpret the real-time signals available on the rig. This contribution presents an implementation of semantic interoperability using OPC UA technology. It translates the principles developed through joint industry efforts into actual drilling operations.

Methods, Procedures, Process
The process used the steps of characterizing the drilling real-time data with semantic graphs, and then developing methods to transfer this characterization to an operational real-time environment.
A semantic interoperability API (application programming interface) uses the semantic modelling capabilities of OPC UA. Its objectives are to facilitate the acquisition and identification of real-time signals (for data consumers) and their precise description (by data providers). The different components of the API reflect the diversity of scenarios one can expect to encounter on a rig: from WITS-like data streams with minimal semantics to fully characterized signals. The high-level interface makes use of semantical techniques, such as reasoning, to enable advanced features like validation or graph queries.

Results, Observations, Conclusions
The implementation phase resulted in a series of open-source solutions that cover all the stages of semantic interoperability. The server part integrates real-time sources and exposes their semantics. Data providers can use dedicated applications to accurately describe their own data, while data consumers have access to both predefined mechanisms and to more advanced programming interfaces to identify and interpret the available signals.
To facilitate the adoption of this technology, test applications are available that allow interested users to experiment and validate their own interfaces against realistic drilling data.
Finally, demonstrations involving several participants took place. The paper discusses both the testing procedures, the results and insights gained.

Novel/Additive Information
The solutions described in this contribution build on newly developed interoperability strategies: they make on-going industry efforts available to the community via modern technologies, such as OPC UA, semantic modelling, or reasoning.
Our hope is that the adoption of the developed technology should greatly facilitate the deployment of next generation drilling automation systems.
Geothermal Drilling – Collaborative and Holistic Applications Specific Solutions Drive Consistent Improvements in Drilling Efficiency and Operational Costs
Authors: Mensa-Wilmot Graham , Cotanda Rufino , Pazziuagan Dexter 
Published: March 2023

Abstract
Geothermal assets continue to be developed aggressively in several regions around the world, fueled by the need to develop clean sources of energy and the recognition that geothermal energy is one such source. As expected, most Geothermal projects are planned and executed using legacy oil/gas drilling systems, tools, and strategies. While effective in some instances, this approach introduces risks, limitations, and inefficiencies into the geothermal drilling process. Consequently, project cycle times and operational costs are usually higher than expected, with additional negative effects on energy production levels and efficiencies.
These challenges need prompt solutions, which must be achieved through development of geothermal specific technologies and strategies. Such considerations are needed to promote drilling efficiency improvements, sustainable project cost reductions, and facilitation of expanded geothermal asset development. In support of required efforts, this paper presents structured processes that guide the interpretation and understanding of geothermal drilling applications and promote holistic development of geothermal specific solutions. The positive effects of a holistic approach and other processes on geothermal drilling, with a focus on improved efficiencies, cycle time and operational costs reductions, will be presented with supporting field data.
Intelligent Tracers for Fluid Invasion Tracking During Coring Operations
Authors: Al-Qasim Abdulaziz , Godbole Atul , Tayyib Deena , Wurtz Marie , Hartvig Sven 
Published: March 2023

Abstract
Core analysis, if conducted successfully, can provide accurate assessment of the original reservoir fluid properties, however, it is challenging to retrieve an uncontaminated core, due to mud components contaminating the fluids originally present in the reservoir. Due to invasion, the liquid extracted from the cores, does not necessarily represent the native liquid, but rather a mixture of drilling and reservoir fluid, thus affecting the results, conclusions and decisions that were based on the analysis. Therefore, deploying advanced water-based mud (WBM) tracers, during coring operations, can mitigate this issue and lead to a significant cost-reduction in field development.
Tracer technology is an efficient monitoring and surveillance tool, that was proven to help in tracking and understanding the injection flow paths, and estimating the remaining oil saturation (Sor) in the reservoir, through inter-well and single-well tracer tests. Utilizing water-based tracers in the drilling mud, during coring operation, can help in quantifying the degree of invasion in the retrieved cores, therefore proper correction and more accurate assessment of the reservoir rock and fluid properties, can be made.
The accuracy of the data plays a pivotal role in guiding the way forward and the future development of oilfield projects. A WBM tracer was utilized in the drilling mud, during the sidetracking of an observation well at the first and largest CO2-Project in the middle east. The objective of sidetracking the well was to obtain sponge core samples to assess the residual oil saturation (ROS) and evaluate the sweep efficiency of the CO2-flood.
This report provides an overview of tracer technologies and the lessons learnt from deploying advanced water-based mud (WBM) tracers during the coring operation of a CO2 observation well, including theoretical and experimental considerations, engineering design and field test issues. The objective of this tracer survey was to estimate the invasion of the drilling mud-filtrate and correct water saturations. It will be useful to use this deployment in some of the relatively mature fields, however, it may have some limitations and challenges that need to be addressed first.
A General Framework to Describe Drilling Process States
Authors: Cayeux Eric , Macpherson John , Pirovolou Dimitrios , Laing Moray , Florence Fred 
Published: March 2023

Abstract
Automation and digitalization of drilling requires shared knowledge about the state of the drilling process: is the bit on-bottom drilling or is the driller making a connection; is the borehole in good condition or is it sloughing? Yet there is no shared, clear and usable definition of what a drilling process state is, nor an agreed method to calculate it. In this paper, we propose a method to clarify the concept of drilling process state. A set of partial differential equations, respecting boundary conditions, can describe drilling operations. The set of all possible discrete changes of boundary conditions, therefore, defines the set of all possible drilling process states. Equality or inequality of logical expressions of at most two boundary values characterizes a discrete change of a boundary condition. For instance, if forces applied to the bit by the formation are zero, this corresponds to an off-bottom condition, while forces greater than zero means that the bit is on-bottom. Such simple logical conditions are microstates, and an orthogonal set of microstates defines a drilling process state. An analysis of the drilling process from the perspective of these microstates defines an orthogonal basis of microstates. It is possible to define uniquely any drilling process state in this orthogonal basis. There are a finite number of possibilities to move from one state to a different state by changing only one single microstate, which leads to the construction of an implicit graph of possible states. In this implicit state graph, the change from one state to another state that corresponds to more than one modification of the microstates corresponds to a path in the graph. However, the microstate basis depends on the type of drilling process. The paper will provide examples of different microstate bases for conventional drilling, backpressure managed pressure drilling, and dual-gradient managed pressure drilling. Microstates also cover abnormal drilling conditions, such as hanging on a ledge, or flow obstruction in the annulus by a pack-off. They are, therefore, more powerful descriptors than "rig activity codes". The required fidelity of the drilling process state depends on its use, for example for controlling drilling equipment (process control), for calculating key performance indicators (process statistics), or for user feedback (human factors engineering). This work is part of the D-WIS initiative (Drilling and Wells Interoperability Standard). D-WIS is a cross-industry workgroup providing the industry with solutions facilitating interoperability of computer systems at the rig site. The definition of a microstate is a simple logical statement, easily implemented in computer software. The paper provides an example of a simple algorithm, which will enable others to leverage the work in the commercial, interoperable, environment.
Continuous Improvement for Offshore Plug and Abandonment, a Case Study from Egypt Offshore
Authors: El Nadoury Mohamed , Balbaa Ola , Vincent James , Eberhardt Todd , Moussa Mohamed , Galal Alaa , ElKholy Sherif , Younan Joseph , Sabra Mohamed , Bogaerts Martijn 
Published: March 2023

Abstract
Setting cement plugs is a critical operation, often not getting the required attention and potentially resulting in lost time. For example, while drilling an exploratory well offshore Egypt in the North Ras el Ash block, special attention was given early in the well's design phase to the wellbore abandonment to be executed after reaching the well target and achieving all well's objectives.
As part of the continuous improvement, a detailed after-action review (AAR) took the place of the abandonment of the previous exploration well in the same field ahead of spud. All applicable lessons learned were identified and worked out in easy-to-implement steps to improve the chances of a successful abandonment meeting all company and regulatory requirements. The AAR addressed all aspects of the abandonment, including cement slurry design and laboratory testing, cement plug placement and operational rig procedures, and post-placement activities that could impact the cement plug and, in the worst case, could lead to not meeting abandonment requirements.
All plugs to be verified by a positive and negative pressure test were simulated using proprietary software. The simulation results would predict the cement plug bonding to the formation or casing during and after the positive and negative tests. To overcome any damage in the sealing capability of the plug, those plugs were designed so that the slurry would expand during the cement setting phase. In addition, detailed laboratory tests were run to optimize the cement slurry design at actual downhole conditions.
Special attention was given to formation pressures and possible losses or influx after cutting and retrieving the intermediate casing. Certain shales are gas-bearing formations but with very low permeability and very low capability to deliver gas to the wellbore. During the drilling phase, this is not considered a high risk and was easily managed with drilling fluids. However, while setting plugs, a small influx of gas can percolate through the cement plug creating a potential leak path.
Correct placement in the field is equally important to a good design. The plug placement was simulated to minimize contamination during placement for plugs. Optimum spacer volume, underdisplacement, and the use of mechanical separators were optimized to achieve the plug and abandonment (P&A) objectives. Pull out of hole (POOH) was designed to minimize disturbance of the cement plug and circulation at top of cement (TOC) was performed without disturbing the cement/spacer interface.
All the effort placed into the well abandonment during the well design phase paid out during the execution. A total of five cement plugs were planned. The plugs were tagged and tested achieving all the abandonment requirements successfully. No repeat plugs were required.