Drilling Operations Research Articles

The Application of Well Control Technology in Drilling Process

Tarim Oilfield, as an important petroleum base in China, faces complex drilling challenges and risks. Well control technology plays a crucial role in this context, involving various aspects such as well control design, drilling fluid technology, and well control equipment. In the geologically complex environment of Tarim Oilfield, it is necessary to develop specific well control strategies tailored to the specific situation. The application of technologies such as drilling fluid technology, well control equipment, and real-time monitoring contributes to achieving safe and efficient drilling operations. This article evaluates the effectiveness of well control technology applications, combines practical case analyses, summarizes lessons learned, and provides guidance for future technological innovation and development directions. It also provides a theoretical foundation for well control in the exploration and development of Tarim Oilfield.

Research on the dynamic behavior of flexible drilling tools in ultrashort-radius radial horizontal wells

A flexible drilling tool is a special drilling tool for ultrashort-radius radial horizontal wells. This tool is composed of many parts and has the characteristics of a multibody system. In this paper, a numerical method for the dynamic analysis of flexible drilling tools is proposed. The flexible drill tool is discretized into spatial beam elements, while the multilayer contact of the flexible drilling tool is represented by the multilayer dynamic gap element, and the dynamic model of the multibody system for the flexible drilling tool’s multilayer contact is established, considering the interaction force between the drill bit and the rock. The nonlinear dynamic equation is solved using the Newmark method and Newton–Raphson method. An analysis of the dynamic behavior of a flexible drilling tool is conducted. The results indicate that the flexible drilling tool experiences vortex formation due to the interaction between the flexible drilling pipe and the guide pipe, leading to increased friction and wear. This situation hinders safe drilling operations with flexible drilling tools. The collision force of the flexible drilling tool near the bottom of the hole is more severe than that of the other tool types, which may lead to failure of the connection.

A New Empirical Correlation for Pore Pressure Prediction Based on Artificial Neural Networks Applied to a Real Case Study

Pore pressure prediction is a critical parameter in petroleum engineering and is essential for safe drilling operations and wellbore stability. However, traditional methods for pore pressure prediction, such as empirical correlations, require selecting appropriate input parameters and may not capture the complex relationships between these parameters and the pore pressure. In contrast, artificial neural networks (ANNs) can learn complex relationships between inputs and outputs from data. This paper presents a new empirical correlation for predicting pore pressure using ANNs. The proposed method uses 42 datasets of well log data, including temperature, porosity, and water saturation, to train ANNs for pore pressure prediction. The trained model, with the Bayesian regularization backpropagation function, predicts the pore pressure with an average absolute percentage error (AAPE) and correlation coefficient (R) of 4.22% and 0.875, respectively. The trained ANN is then used to develop a new empirical correlation that relates pore pressure to the input parameters considering the weights and biases of the optimized ANN model. To validate the proposed correlation, it is applied to a blind dataset, where the model successfully predicts the pore pressure with an AAPE of 5.44% and R of 0.957. The results show that the proposed correlation provides accurate and reliable predictions of pore pressure. The proposed method provides a robust and accurate approach for predicting pore pressure in petroleum engineering applications, which can be used to improve drilling safety and wellbore stability.

Temperature-Sensitive Materials for Oil and Gas Drilling Applications.

With the vigorous development of the petroleum industry, improving the efficiency of oil and gas exploitation has become an important issue. Temperature-sensitive materials show great potential for application in the development and production of oil and gas fields due to their unique temperature-responsive properties. This paper reviews the application of temperature-sensitive materials in oil and gas drilling and introduces the characteristics of three types of temperature-sensitive materials: N-substituted acrylamide polymers, amphiphilic block copolymers, and peptides. Because these materials can change their physical state at specific temperatures, this paper discusses in detail the role of various temperature-sensitive materials as plugging agent, thickener, oil displacing agent, flocculant, and tackifier in oil and gas field operations, as well as the mechanism of action and performance of temperature-sensitive materials in practical oil and gas drilling operations. As we have not yet seen relevant similar literature, this paper aims to discuss the innovative application of temperature-sensitive materials in the oil and gas drilling process, and at the same time points out the problems in the current research and applications as well as future development directions. Through analysis and comparison, we provide an efficient and environmentally friendly materials selection option for the petroleum industry in order to promote the progress and sustainable development of oil and gas extraction processes.

Identification method for safety hazard behavior in offshore drilling operators

During offshore drilling operations, both human inexperience and fatigue can contribute to drilling stagnation, overflow, blowout, and other accidents. Despite significant advancements in the automation of equipment and facilities on offshore drilling platforms, humans continue to play a central role in drilling operations. Utilizing the TPE-LightGBM model, a method for identifying safety hazard behavior among offshore drilling operators based on eye movement data was proposed. The main contributions of the present study are as follows: Firstly, the application of eye-tracking technology to identify safety hazards among offshore drilling operators overcomes the lack of risk perception and monitoring methods for mitigating the safety hazards experienced by operators. Secondly, a method utilizing composite hotspot mapping for eye movement to determine sensitive area divisions during offshore drilling operations was proposed. This method aims to reduce the influence of irrelevant, missing, and incorrect eye movement data on recognition results. Thirdly, in conjunction with qualitative selection and analysis of eye movement laws, a feature selection method for eye movement in the context of safety hazard behavior in offshore drilling was proposed. This method enhances the efficiency of recognizing safety hazard behavior. Lastly, the TPE algorithm was introduced to enhance the LightGBM model, addressing the issue of inaccurate identification of safety hazard behavior in offshore drilling operators. The results indicate that the proposed method effectively enhances the accuracy and execution efficiency for identifying safety hazard behavior among offshore drilling operators.

A review of the Carboniferous shale gas potential of northern England: a data-based analysis of why it won't work

Abstract The recent shale gas revolution originated in the USA in the late 1990s with the exploration of the Carboniferous Barnett Shale in Texas. Success in a number of additional basins in North America, such as the Marcellus, Eagle Ford and Bakken basins, stimulated a search for similar opportunities elsewhere around the world. Among the shales and basins targeted by industry was the Carboniferous Bowland Shale (and equivalents) in northern England. The initial premise that the Barnett Shale represented an excellent analogue for the Bowland Shale led to over-optimistic reserve estimates that have since been shown to be largely incorrect. On the basis of visual inspection of wellbore cores, the Carboniferous Barnett and Bowland shales appear to be very similar. Unfortunately, it is there that the similarity ends. Research carried out for the UK Unconventional Hydrocarbons project has highlighted important differences adversely impacting prospectivity. These can be summarized as basin type/continuity and structural complexity. The total organic carbon, maturity, mineralogy and thickness of the Bowland Shale and equivalents are broadly similar to the successful US examples. Our conclusion is that the Bowland Shale in the UK does not represent a technically significant resource, and in hindsight did not merit the considerable industry and media attention that has been associated with it. One key learning is that fundamental research based on heritage data and modern analytical and modelling techniques should have preceded drilling and fracking operations in northern England.

Research on adaptive prediction model of rate of penetration under dynamic formation conditions

Rate of Penetration (ROP) prediction is a crucial for optimizing drilling processes and enhancing drilling efficiency. However, most existing ROP prediction models are static, relying on fixed neighboring well datasets and incapable of adapting to real-time changes in formation conditions during drilling. The dynamic and uncertain nature of geological conditions and formation heterogeneity further limits the extension and application of current ROP prediction models to target wells. To address these challenges, this study introduces an Adaptive Random Forest (ARF) algorithm to establish an ROP adaptive prediction model under dynamic formation conditions during real-time drilling operations. The performance of the ARF model is compared with the Moving-Window Random Forest (MW-RF) ROP dynamic prediction model, using data from the W1 well in the Sichuan basin as an example. Experimental results demonstrate that the ARF model outperforms the MW-RF model, exhibiting smaller overall error and reduced error fluctuation during formation condition changes. The ARF model's dynamic adaptability allows it to respond to the evolving trends of the ROP prediction model, rapidly adjusting to changes in formation conditions based on real-time drilling data flow. In contrast, the MW-RF model exhibits slower adaptability and delays in updating, reacting passively to window movements. The proposed ARF model overcomes limitations associated with static ROP prediction models, making it applicable to practical drilling scenarios and providing a theoretical foundation for real-time drilling parameter optimization and intelligent drilling strategies.

Dynamic catastrophe analysis of deepwater mooring platform/riser/wellhead coupled system under ISW

Mooring platform/riser/wellhead coupled system, as an important and large complex system during offshore drilling operations, is easily affected by internal solitary waves (ISW). The impact load of ISW may lead to failure cascade process and even serious accident consequences to the coupled system. This paper is aimed at proposing a dynamic catastrophic analysis model that combines mechanical quantitative analysis with process safety of mooring platform/riser/wellhead system under ISW. The proposed dynamic catastrophic model can consider limit state of each system used as the failure criterion, including the dragging/fracture of mooring system and the fracture failure of riser/wellhead/conductor system. A dynamic catastrophic analysis method was proposed and a simulation program was also developed based on MATLAB. A case study was presented to reveal the dynamic catastrophic evolution process and the susceptibility of coupled system to ISW. Results indicated that the coupled system would experience wellhead fracture, mooring line dragging or fracture, riser fracture, and flex joint failure under different ISW velocities. Through the quantitative analysis with different ISW strength, two catastrophic scenarios, namely, wellhead fracture-mooring line dragging and mooring line dragging-wellhead fracture-mooring line dragging, occurred.

Prediction and Optimization of Cutting Forces required to Minimize Tool Breakage during Dry Drilling Operations

Drilling is one of the most common and rudimental machining methods in the manufacturing industries for removal of unwanted material from the workpiece. How the cutting instrument and workpiece interact results in a mechanical force that causes the formation of chips during penetration, and these chips are evacuated through the flute created on the body of the drill tool. The interplay of forces at the drill point generates high temperatures, needed for the physical and chemical processes that weaken tools and lead to breakage. Optimal experimental designs are very important to obtain accurate optimization of engineering processes, an expert method was used to design the experimental layout and utilizing the Design Expert software, an experimental matrix which developed the parameters design of twenty experimental runs. The present study uses Artificial Neural Networks (ANN) and Response Surface Methodology (RSM) to forecast and optimize cutting forces during dry drilling operations. In developing the model, a dataset that included several factors such as depth of cut, feed rate, and cutting speed was used. The RSM model demonstrated a significant correlation between input parameters and cutting forces, as evidenced by its high coefficient of determination (R²) of 0.9493. On the other hand, the ANN model, which was trained using 70% of the data and validated using 15% of the data, showed a little lower R² value of 0.81434, but it was still able to make accurate predictions. Cutting forces were well predicted by both models, with RSM exhibiting a somewhat better performance in terms of accuracy. The results indicate that both RSM and ANN can be useful instruments for dry drilling cutting force optimization, offering insights for increased productivity and efficiency in machining operations.

Wellbore instability in naturally fractured formations: Experimental study and 3D numerical investigation

Wellbore instability due to natural fractures is a significant issue impeding drilling operations in shale formations. However, most of the existing literature on wellbore stability analysis focuses on the coupled effects of fluid flow and deformation, and the impact of three-dimensional natural fracture characteristics on wellbore instability is not yet closely examined. This paper carried out a series of experiments to analyze the shale sample's fracture characteristics and shear strength. A fully coupled 3D hydro-mechanical model was then developed using the distinct element method (DEM) to investigate the wellbore instability. Finally, a comprehensive parametric study was performed to analyze the effects of characteristics of fractures (e.g., distribution density, fracture roughness and associated shear strength, dip angle, and seepage time) on wellbore stability under different in-situ stress states. The results show that the shear strength of shale increases with the increase in normal pressure (4 MPa, 6 MPa, and 8 MPa); the shear strength increases by 64.9% when the roughness is 0.325 mm (the largest increase among the three roughness cases). The maximum displacement around the wellbore is 1.3–1.5 times greater under the presence of weak planes than under no weak planes. Fracture roughness poses an important impact on wellbore stability because larger fracture roughness is associated with higher fracture shear strength. As the dip angle of the weak plane increases, the number of yield zones (shear failure) and maximum wellbore displacement increases and then decreases, and the peak occurs at the dip angle of 45°. The seepage time of drilling fluid is positively correlated with the number of yield zones around the wellbore, and the damage rate of drilling fluid to wellbore stability gradually decreases with the seepage time.

The Investigation of Broad-Spectrum Sealing Drilling Fluid Based on Horsfield Close-Packing Theory

Summary In shale gas drilling operations, oil-based drilling fluids have proved to be effective in addressing the issue of shale reservoir hydration expansion, serving as the primary working fluid for complex subsurface shale formations. However, the presence of shale laminations and the development of microfractures with varying widths require drilling fluids with excellent sealing capabilities. In this study, a comprehensive investigation was conducted to develop a drilling fluid system with broad-spectrum high-sealing performance. The porosity of bridging particles was determined by using the Archimedean drainage method. The bridging particle size and quantity at each level were meticulously designed through leveraging the Horsfield close-packing theory. The incorporation of deformable nanoscale polymer sealing materials further enhanced the sealing performance of the drilling fluid system. Additionally, hydrophobic nanoscale silica particles were introduced as coemulsifier to prepare Pickering emulsions, thereby improving emulsion stability and enhancing particle-size distribution for improved sealing. Through formulation optimization, a drilling fluid system with broad-spectrum, high-sealing performance capabilities was developed. The study revealed a reduction in porosity of closely packed bridging particles from 35.36% to 11.38%. The drilling fluid system exhibited a remarkable sealing efficiency of 99.2% for microfractures in the 1–10 μm range and 95.8% for microfractures in the 30–50 μm range. Furthermore, it demonstrated excellent sedimentation stability, with a sedimentation factor of less than 0.52 after 48 hours of static sedimentation at 150°C. The drilling fluid system also exhibited favorable rheological, lubrication, and inhibition properties, thus meeting the demands of field applications.

Foam Stability Analysis at High pH and Saline Environments for Underbalanced Drilling Operations

Foam Stability Analysis at High pH and Saline Environments for Underbalanced Drilling Operations

Investigating the efficacy of novel organoclay as a rheological additive for enhancing the performance of oil-based drilling fluids

Oil-based drilling fluids (OBDFs) are extensively used in the drilling industry due to their superior performance in challenging drilling conditions. These fluids control wellbore stability, lubricate the drill bit, and transport drill cuttings to the surface. One important component of oil-based drilling fluids is the viscosifier, which provides rheological properties to enhance drilling operations. This study evaluates the effectiveness of Claytone-IMG 400, a novel rheological agent, in enhancing the performance of OBDFs under high-pressure and high-temperature (HPHT) conditions. A comparative analysis was conducted with a pre-existing organoclay (OC) to assess the improvements achieved by Claytone-IMG 400. The OCs were analyzed using X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), and particle size distribution (PSD) to identify their mineral and chemical compositions, morphologies, and particle sizes. The drilling fluid density, electrical stability, sagging tendency, rheological properties, viscoelastic properties, and filtration properties were studied to formulate a stable and high-performance drilling fluid. The results confirmed that the novel OC does not affect the drilling fluid density but enhances the emulsion stability with a 9% increment compared with the drilling fluid formulated with MC-TONE. The sagging experiments showed that Claytone-IMG 400 prevented the sagging issues in both static and dynamic conditions. Also, Claytone-IMG 400 improved the plastic viscosity (PV), yield point (YP), and apparent viscosity (AV). The PV, YP, and AV were improved by 30%, 38%, and 33% increments respectively compared with the drilling fluid formulated with MC-TONE. The YP/PV ratio increased with a 6% increment from 1.12 to 1.19. Moreover, the gel strength (GS) was significantly increased, and the filtration properties were enhanced. The filtration volume was reduced by 10% from 5.0 to 4.5 cm3, and the filter cake thickness had a 37.5% reduction from 2.60 to 1.89 mm. The novelty of this study is highlighted by the introduction and evaluation of Claytone-IMG 400 as a new rheological additive for safe, efficient, and cost-effective drilling operations. The results indicate that Claytone-IMG 400 significantly improves the stability and performance of OBDFs, thereby reducing wellbore instability and drilling-related problems.

Employing Statistical Algorithms and Clustering Techniques to Assess Lithological Facies for Identifying Optimal Reservoir Rocks: A Case Study of the Mansouri Oilfields, SW Iran

The crucial parameters influencing drilling operations, reservoir production behavior, and well completion are lithology and reservoir rock. This study identified optimal reservoir rocks and facies in 280 core samples from a drilled well in the Asmari reservoir of the Mansouri field in SW Iran to determine the number of hydraulic flow units. Reservoir samples were prepared, and their porosity and permeability were determined by measuring devices. The flow zone index (FZI) was calculated for each sample using MATLAB software; then, a histogram analysis was performed on the logarithmic data of the FZI, and the number of hydraulic flow units was determined based on the obtained normal distributions. Electrical facies were determined based on artificial neural network (ANN) and multi-resolution graph-based clustering (MRGC) approaches. Five electrical facies with dissimilar reservoir conditions and lithological compositions were ultimately specified. Based on described lithofacies, shale and sandstone in zones three and five demonstrated elevated reservoir quality. This study aimed to determine the Asmari reservoir’s porous medium’s flowing fluid according to the C-mean fuzzy logic method. Furthermore, the third and fourth flow units in the Asmari Formation have the best flow units with high reservoir quality and permeability due to determining the siliceous–clastic facies of the rock units and log data. Outcomes could be corresponded to the flow unit determination in further nearby wellbores without cores.

PEMBANGUNAN TRANSPORTASI KERETA API JALUR GOENDIH (GROBOGAN) – SOERABAJA TAHUN 1903-1922

This study examines the Goendih-Soerabaja railway line for the period 1903-1922. The purpose of this study is to explain the reasons for the construction of the railroad, the process of building the railroad, and its impact on the surrounding community. The results of this study indicate that the construction of the Goendih-Soerabaja railway line had a positive impact on the economy of the Dutch East Indies Government. Inaugurated on February 1, 1903, rail transportation encouraged economic growth in areas that became the path of the Goendih-Soerabaja railroad. The forced cultivation system has had a major impact on plantations, problems that have occurred due to the damage of export commodities before arriving at the port can now be resolved by the presence of rail transportation. Another factor is that the start of oil drilling operations in the Tjepu area has created the need for large-capacity oil transport in shipping to ports. Another impact of the existence of rail transportation is that the mobility of people who travel now saves more travel time.
 Keywords: Infrastructure; Railroad Extension; Goendih – Soerabaja Line; Capitalist Economy.

Geomechanical Characterization of the Rock Mass along a Deep Vertical Borehole

Deep vertical boreholes play a crucial role in underground exploration, resource extraction such as geothermal energy extraction, oil and gas exploration, underground waste storage and various underground engineering applications. The geomechanical properties of the rocks surrounding these boreholes are essential for designing safe, efficient drilling operations, for using adequate technologies and equipment and for providing mitigation measurements. Specifically, when the excavations are performed inside in-depth, extremely fractured and weathered rocks, the identification of zones more susceptible to crossing is a primary goal. This paper presents a thorough investigation into the rock masses surrounding a deep vertical borehole that involved the collection of core samples from the deep vertical borehole, laboratory testing, in situ tests and the application of geomechanical models to characterize the crossed rock masses. After a lithological and structural description of the rock masses and a description of the methodology used for their characterization, this paper focuses on the geomechanical parameterization of the rock mass using the uniaxial compressive strength of the intact rock (σci) and the Geological Strength Index (GSI). The obtained findings highlight the extreme variability in the depth of the geomechanical parameters of crossed rocks, which decreased with the depth. This methodology can be used to characterize rock masses along other deep boreholes, for which there is a lack of research, and to define the most problematic zones for underground crossing where different support works must be designed.

Drilling performance of micro-textured twist drill bit for TI-6AL-4V alloy: Validated FEM and statistical approaches

The titanium alloy, particularly Ti-6Al-4V, is an extensively demanded material in diverse sectors because of its superior physical and chemical properties. Nevertheless, the inherent hardness of the material causes challenges during machining operations. The alloy's heat-resistance characteristic induces increased friction and heat generation on cutting tools, ultimately causing a decrease in the tool life. In an attempt to overcome this issue, numerous forms of surface texturing have been investigated with the aim of improving the tribological characteristics of the material. The aim of the present investigation was to enhance the cutting performance of drill bits by implementing micro-textured patterns, hence minimizing thrust force, torque, and tool temperature. The combined effect of three distinct micro-textured geometries on a drill bit's flank, flute, and margin surfaces, with the influence of coating conditions, on the performance of drilling operations was investigated. The Finite Element Method (FEM) was used to perform a range of varied drilling operations. The Grey Relation Analysis (GRA) and General Linear Model (GLM) were employed to assess and compare the drilling performances with respect to thrust force, torque, and drill bit temperature. It was found that the square-sectioned textures on the side face exhibited the most obvious influence on the drilling performance. In the meantime, the textures found on the flute face were identified as having a comparatively smaller influence. The ideal configuration for the drill bit entailed a flank face with a square sectioned texture, a flute face without any texture, a margin face with a square sectioned texture, and a hard coating. As a result, the current situation substantially reduced cutting forces, tool wear, and tool temperature by 51 %, 20.5 %, and 23.4 % compared to the drilling condition without textured drill bits.

Liquid Flow Patterns and Particle Settling Velocity in a Taylor-Couette Cell Using Particle Image Velocimetry and Particle Tracking Velocimetry

Summary Controlling the downhole pressure is an important parameter for successful and safe drilling operations. Several types of weighting agents (i.e., high-density particles), traditionally barite particles, are added to maintain the desired density of the drilling fluid (DF). The DF density is an important design parameter for preventing multiple drilling complications. These issues are caused by the settling of the dense particles, an undesired phenomenon also referred to as sagging. Therefore, there is a need to understand the settling characteristics of heavy particles in such scenarios. To this end, simultaneous measurements of liquid phase flow patterns and particle settling velocities have been conducted in a Taylor-Couette (TC) cell with a rotating inner cylinder and stationary outer cylinder separated by an annular gap of 9.0 mm. Liquid flow patterns and particle settling velocities have been measured using particle image velocimetry (PIV) and particle tracking velocimetry (PTV) techniques, respectively. Experiments have been performed by varying the rotational speed of the inner cylinder up to 200 rev/min, which is used in normal drilling operations. Spherical particles with diameters of 3.0 mm or 4.0 mm and densities between 1.2 g/cm3 and 3.95 g/cm3 were used. The liquid phases studied included deionized (DI) water and mineral oil, which are the basic components of a non-Newtonian DF with a shear-thinning viscosity. The DF is a mud-like emulsion of opaque appearance, which impedes the ability to observe the liquid flow field and particle settling in the TC cell. To address this issue, a solution of carboxymethyl cellulose (CMC) with a 6% weight concentration in DI water was used. This non-Newtonian solution displays shear-thinning rheological behavior and was used as a transparent alternative to the opaque DF. For water, PIV results have shown wavy vortex flow (WVF) to turbulent Taylor vortex flow (TTVF), which agrees with the flow patterns reported in the literature. For mineral oil, circular Couette flow (CCF) was observed at up to 100 rev/min and vortex formation at 200 rev/min. For CMC, no vortex formation was observed up to 200 rev/min, only CCF. The settling velocities for all particles in water matched with the particle settling velocities predicted using the Basset-Boussinesq-Oseen (BBO) equation of motion. For mineral oil and CMC, the results did not match well with the predicted settling velocities, especially for heavy particles due possibly to the radial particle migration and interactions with the outer cylinder wall.

Autonomous Drilling Approach Uses Rotary Steerable System in Middle East Wells

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper IPTC 22975, “Novel Approach to Autonomous Drilling Using Rotary Steerable System in Middle Eastern Oil and Gas Wells,” by Victor Oliveira, Saudi Aramco, and Mohammed Elsadig and Ayman Al-Ghazzawi, SPE, SLB, et al. The paper has not been peer reviewed. Copyright 2023 International Petroleum Technology Conference. Reproduced by permission. _ An operator focused on evaluating and validating a novel approach from its major directional-drilling-service provider using the autocurve-drilling mode to drill curved sections automatically without human intervention. The autonomous curve-drilling technology helped minimize human error, enhance accuracy of well positioning, and improve hole quality for drilling and workover operations. Autocurve-Drilling System Rotary-steerable-system (RSS) intelligence has been improving since its introduction. Around 1990, when the RSS method was introduced, communication with RSS tools was only one-way; downlink commands were sent through flow variations, and the response was monitored. For corrections, human intervention was required by sending new downlink commands. Between 2003 and 2013, downhole automation design and analysis for RSS began with the introduction of closed-loop features in which either verticality or target inclination and azimuth in tangent sections can be maintained. The technology evolved to closed-loop responses in these vertical or tangent modes to adjust the trajectory automatically to the target directions within 0.5° in inclination and 2° in azimuth. The next step for automating the downhole trajectory control of RSS was to close-loop the curve section. This once took increased levels of focus from directional drillers to ensure that they continued reviewing directional responses of the RSS in different intervals to update steering requirements, the steering ratio, and toolface commands. This was a good driver for further improvement of RSS intelligence and updates to desired steering-requirement capabilities to automate curve-section directional control. An autocurve autonomous downhole-automation-control system was developed to address the need to automate curved-section directional control. The intelligent algorithm was developed to change the communication process from including surface intervention to use of only a downhole closed-loop system once directional requirements were established. The system moved away from toolface and steering-ratio downlinking commands to dogleg and toolface commands. As a result, the RSS is no longer dependent on surface intervention for steering requirements but adapts to deliver required dogleg-severity (DLS) commands. This process solved the need for surface dependency. Upon acquiring this information, the tool uses the latest-known inclination and azimuth, and programmed rate of penetration, to create pseudochanges in direction and inclination to follow and automatically calculates a steering ratio to follow the required path. This closed-loop design is performed on a continuous basis within 1 second compared with the average 20-minute process cycle that was used conventionally. Furthermore, the design minimizes the command-downlink requirements to the tool, which further enables the automation path.

Investigation and Analysis of Influential Parameters in Bottomhole Stick–Slip Calculation during Vertical Drilling Operations

The critical factors that affect bottomhole stick–slip vibrations during vertical drilling operations are thoroughly investigated and analyzed in this research. Influential factors, such as rotation speed, weight on bit (WOB), bottom hole assembly (BHA) configuration, and formation properties, were studied in order to understand their part in the stick–slip phenomena. The analysis is based on a thorough review of previous research conducted on stick–slip drilling vibrations. A mathematical model was created that not only explains axial vibrations but also includes the torsional vibrations present in stick–slip occurrences, which helps with understanding the stick–slip phenomena better. This model can be used as an analytical tool to predict and evaluate the behavior of drilling systems under various operational circumstances. Furthermore, two drilling tests using a WellScan simulator were performed to validate the research findings and assess mitigation techniques’ viability. These test scenarios reflect the stick–slip vibration-producing situations, allowing us to test mitigation strategies. The finding of this study shows the effectiveness of two tactics for reducing stick–slip vibrations. First was the reduction of WOB, which successfully lowered the occurrence of stick–slip vibrations. The second was the increase in the rotation speed, which helped to control the stick–slip problem and increased the drilling speed. This study explains the complex dynamics of stick–slip vibrations during vertical drilling and offers practical, tried-and-true methods for reducing their adverse effects on drilling operations.