A Dynamic Model for Rotary Rock Drilling

1982 ◽  
Vol 104 (2) ◽  
pp. 108-120 ◽  
Author(s):  
I. E. Eronini ◽  
W. H. Somerton ◽  
D. M. Auslander
Keyword(s):  
Drill Pipe ◽  
Tooth Wear ◽  
Drill String ◽  
Rock Drilling ◽  
Large Power ◽  
Drilling Rig ◽  
Drilling Performance ◽  
Weight On Bit ◽  
Rotary Speed ◽  
Mud Pressure

A rock drilling model is developed as a set of ordinary differential equations describing discrete segments of the drilling rig, including the bit and the rock. The end segment consists of a description of the bit as a “nonideal” transformer and a characterization of the rock behavior. The effects on rock drilling of bottom hole cleaning, drill string-borehole interaction, and tooth wear are represented in the model. Simulated drilling under various conditions, using this model, gave results which are similar to those found in field and laboratory drilling performance data. In particular, the model predicts the expected relationships between drilling rate and the quantities, weight on bit, differential mud pressure, and rotary speed. The results also suggest that the damping of the longitudinal vibrations of the drill string could be predominantly hydrodynamic as opposed to viscous. Pulsations in the mud flow are found to introduce “percussive” effects in the bit forces which seem to improve the penetration rate. However, it is known from field observations that drill pipe movements, if strong enough, may induce mud pressure surges which can cause borehole and circulation problems. Bit forces and torques are shown to be substantially coupled and the influence of certain rock parameters on variables which are measurable either at the bit or on the surface support the expectation that these signals can furnish useful data on the formation being drilled. Other results, though preliminary, show that the effects of the lateral deflections of the drill string may be large for the axial bit forces and significant for the torsional vibrations. For the latter, the unsteady nature of the rotation above the bit increases and the resistance to rotation due to rubbing contact between the drill string and the wellbore accounts for very large power losses between the surface and the bit.

Drilling System Optimization Leads to Expedited Wells Delivery

2021 ◽  
Author(s):  
Efe Mulumba Ovwigho ◽  
Saleh Al Marri ◽  
Abdulaziz Al Hajri
Keyword(s):  
Drill Pipe ◽  
System Optimization ◽  
Drill String ◽  
Stick Slip ◽  
Drilling Performance ◽  
Drilling Parameters ◽  
Single String ◽  
Innovative Solution ◽  
Open Hole ◽  
Weight On Bit

Abstract On a Deep Gas Project in the Middle East, it is required to drill 3500 ft of 8-3/8" deviated section and land the well across highly interbedded and abrasive sandstone formations with compressive strength of 15 - 35 kpsi. While drilling this section, the drill string was constantly stalling and as such could not optimize drilling parameters. Due to the resulting low ROP, it was necessary to optimize the Drill string in order to enhance performance. Performed dynamic BHA modelling which showed current drill string was not optimized for drilling long curved sections. Simulation showed high buckling levels across the 4" drill pipe and not all the weight applied on surface was transmitted to the bit. The drilling torque, flowrate and standpipe pressures were limited by the 4" drill pipe. This impacted the ROP and overall drilling performance. Proposed to replace the 4" drill pipe with 5-1/2" drill pipe. Ran the simulations and the model predicted improved drill string stability, better transmission of weights to the bit and increased ROP. One well was assigned for the implementation. Ran the optimized BHA solution, able to apply the maximum surface weight on bit recommended by the bit manufacturer, while drilling did not observe string stalling or erratic torque. There was also low levels of shocks and vibrations and stick-slip. Doubled the on-bottom ROP while drilling this section with the same bit. Unlike wells drilled with the previous BHA, on this run, observed high BHA stability while drilling, hole was in great shape while POOH to the shoe after drilling the section, there were no tight spots recorded while tripping and this resulted in the elimination of the planned wiper trip. Decision taken to perform open hole logging operation on cable and subsequently run 7-in liner without performing a reaming trip. This BHA has been adopted on the Project and subsequent wells drilled with this single string showed similar performance. This solution has led to average savings of approximately 120 hours per well drilled subsequently on this field. This consist of 80 hours due to improved ROP, 10 hrs due to the elimination of wiper trip and a further 30 hrs from optimized logging operation on cable. In addition, wells are now delivered earlier due to this innovative solution. This paper will show how simple changes in drill string design can lead to huge savings in this current climate where there is a constant push for reduction in well times, well costs and improved well delivery. It will explain the step-by-step process that was followed prior to implementing this innovative solution.

A Modular Mechanism for Downhole Weight-on-Bit and Torque Reaction in Small Diameter Boreholes

2021 ◽  
pp. 1-15
Author(s):  
Anirban Mazumdar ◽  
Stephen Buerger ◽  
Adam Foris ◽  
Jiann-cherng Su
Keyword(s):  
Axial Force ◽  
Small Diameter ◽  
Field Testing ◽  
Drill String ◽  
Force Transmission ◽  
Drilling Performance ◽  
Weight On Bit ◽  
In Series ◽  
Mechanical Devices ◽  
Scalable Design

Abstract Drilling systems that use downhole rotation must react torque either through the drill-string or near the motor to achieve effective drilling performance. Problems with drill-string loading such as buckling, friction, and twist become more severe as hole diameter decreases. Therefore, for small holes, reacting torque downhole without interfering with the application of weight-on-bit, is preferred. In this paper we present a novel mechanism that enables effective and controllable downhole weight on bit transmission and torque reaction. This scalable design achieves its unique performance through four key features: 1) mechanical advantage based on geometry, 2) direction dependent behavior using rolling and sliding contact, 3) modular scalability by combining modules in series, and 4) torque reaction and weight on bit that are proportional to applied axial force. As a result, simple mechanical devices can be used to react large torques while allowing controlled force to be transmitted to the drill bit. We outline our design, provide theoretical predictions of performance, and validate the results using full-scale testing. The experimental results include laboratory studies as well as limited field testing using a percussive hammer. These results demonstrate effective torque reaction, axial force transmission, favorable scaling with multiple modules, and predictable performance that is proportional to applied force.

Drilling in the Digital Age: Machine Learning Assisted Bit Selection and Optimization

2021 ◽  
Author(s):  
Peter Batruny ◽  
Hafiz Zubir ◽  
Pete Slagel ◽  
Hanif Yahya ◽  
Zahid Zakaria ◽  
...  
Keyword(s):  
Machine Learning ◽  
Monte Carlo Analysis ◽  
Specific Model ◽  
Planning Decisions ◽  
Drilling Performance ◽  
Weight On Bit ◽  
Data Points ◽  
Ideal Tool ◽  
Rotary Speed ◽  
Artificial Neural Network Ann

Abstract Conventionally, a bit is selected from offset well bit run summaries. This method of selection is not always accurate since each bit is run under different conditions which might not be reflected in an offset study analysis. The large quantities of data generated from real time measurements in offset wells makes machine learning the ideal tool for analysis and comparison. Artificial Neural Network (ANN) is a relatively simple machine learning tool that combines inputs and calculation layers to compute a specified output layer. The ANN is fed over thousands of data points from 17-1/2 in hole sections across multiple wells. A specific model is then trained for every bit with weight on bit (WOB), rotary speed (RPM), bit hydraulics, and lithological properties as inputs and rate of penetration (ROP) as output. The model is finalized when a satisfactory statistical set of KPI's are achieved. Using a combination of Monte-Carlo analysis and sensitivity analysis, different bits are compared by varying parameters for the same bit and varying the bit under the same parameters. A bit and its optimized parameters are proposed, resulting in an average instantaneous ROP improvement of 32%. Performance benchmarked with individual drilling parameters shows improved ROP response to WOB, RPM, and bit hydraulics in the optimized run. This project solidifies machine learning as a powerful tool for bit selection and parameter optimization to improve drilling performance. Machine learning will become a significant part of well planning, design, and operations in the future. This study demonstrates how ANN's can be used to learn from previous operations and influence planning decisions to improve bit performance.

Drilling Cutting Analysis to Assist Drilling Performance Evaluation in Hard Rock Hole Widening Operation

2020 ◽  
Author(s):  
Daiyan Ahmed ◽  
Yingjian Xiao ◽  
Jeronimo de Moura ◽  
Stephen D. Butt
Keyword(s):  
Performance Enhancement ◽  
Ore Deposits ◽  
Drilling Process ◽  
Rotary Drilling ◽  
Pilot Hole ◽  
Drilling Rig ◽  
Drilling Performance ◽  
Drilling Parameters ◽  
Weight On Bit ◽  
Drilling Operations

Abstract Optimum production from vein-type deposits requires the Narrow Vein Mining (NVM) process where excavation is accomplished by drilling larger diameter holes. To drill into the veins to successfully extract the ore deposits, a conventional rotary drilling rig is mounted on the ground. These operations are generally conducted by drilling a pilot hole in a narrow vein followed by a hole widening operation. Initially, a pilot hole is drilled for exploration purposes, to guide the larger diameter hole and to control the trajectory, and the next step in the excavation is progressed by hole widening operation. Drilling cutting properties, such as particle size distribution, volume, and shape may expose a significant drilling problem or may provide justification for performance enhancement decisions. In this study, a laboratory hole widening drilling process performance was evaluated by drilling cutting analysis. Drill-off Tests (DOT) were conducted in the Drilling Technology Laboratory (DTL) by dint of a Small Drilling Simulator (SDS) to generate the drilling parameters and to collect the cuttings. Different drilling operations were assessed based on Rate of Penetration (ROP), Weight on Bit (WOB), Rotation per Minute (RPM), Mechanical Specific Energy (MSE) and Drilling Efficiency (DE). A conducive schedule for achieving the objectives was developed, in addition to cuttings for further interpretation. A comprehensive study for the hole widening operation was conducted by involving intensive drilling cutting analysis, drilling parameters, and drilling performance leading to recommendations for full-scale drilling operations.

scholarly journals Drilling Vibration Modes and Penetration Rate Modeling using Artificial Neural Network and Multiple Linear Regression Analysis in Khoman Formation at the Egyptian Western Desert

2021 ◽  
Author(s):  
Sherif A. Ezz ◽  
Mohamed S. Farahat ◽  
Said Kamel ◽  
Ahmed Z. Nouh
Keyword(s):  
Neural Network ◽  
Regression Analysis ◽  
Penetration Rate ◽  
Drill String ◽  
Western Desert ◽  
Circulation Rate ◽  
Vibration Level ◽  
Stick Slip ◽  
Weight On Bit ◽  
Rotary Speed

Abstract Drill string vibrations are one of the most serious problems encountered while drilling as the bit and drill string interaction with formations under certain drilling conditions usually induces complex shocks and vibrations into the drill string components resulting in premature failure of the equipment and reduced drilling penetration rate. In severe cases where shocks and vibrations accumulated into drill string till exceeded its maximum yield or torsional strength, fatigue will occur and thereby increase the field development costs associated with replacing damaged components, fishing jobs, lost-in-hole situations, and sidetracks. Thus, real-time monitoring for downhole generated vibrations and accordingly adjusting drilling parameters including weight on bit, rotary speed, and circulation rate play a vital role in reducing the severity of these undesirable conditions. Vibration optimization must be done incorporation with the penetration rate, as a minimum economical penetration rate is required by the operator. In this study, three penetration rate and vibration level models were developed for axial, lateral, and stick-slip drilling modes using both MATLAB™ Software neural network and multiple regression analysis. It is found that the three models' results for vibration level and penetration rate; as compared with those recorded drilling data; showed an excellent match within an acceptable error of average correlation coefficient (R) over 0.95. The prediction of penetration rate and vibration level is thoroughly investigated in different axial, lateral, and stick-slip vibration drilling modes to be able to best select the optimum safe drilling zone. It is found that the axial vibration could be dampened by gradually increasing the weight on bit and increasing rotary speed while both the lateral and torsional vibrations are enhanced by increasing the rotary speed and decreasing the weight on bit.

scholarly journals An Experimental Investigation of Drilling Performance Improvement Using Reaming While Drilling

2021 ◽  
pp. 1-17
Author(s):  
Abbas Roohi ◽  
Rahman Ashena ◽  
Gerhard Thonhauser ◽  
Thomas Finkbeiner ◽  
Laurent Gerbaud ◽  
...  
Keyword(s):  
Performance Improvement ◽  
Specific Energy ◽  
Laboratory Experiments ◽  
Performance Indicator ◽  
Drill String ◽  
Drilling Rig ◽  
Mechanical Specific Energy ◽  
Drilling Performance ◽  
Drilling Bit ◽  
Conventional Drilling

Abstract This work investigates the drilling performance by reaming while drilling (RWD) using a dual-body bit and compared it with conventional drilling by a standard drilling bit. The dual-body bit consisted of a 2.45-in pilot bit located at a short distance ahead of a 2.47*3.97-in reamer. Conducting a series of drilling experiments at a simulation drilling rig with full monitoring sensors, we further studied the drilling performance as a function of the distance between the pilot bit and the reamer which affect mud diffusion and the resultant change in pore pressure and stress. A method was devised to eliminate the drill-string vibration and its effect on the drilling performance and the energy consumed. The mechanical specific energy (MSE) calculated for each case was considered as a drilling performance indicator. Using two laboratory experiments as well as analytical thermo-poro-elastic calculations of the Mechanical Specific Energy (MSE), the MSE changes were monitored and recorded. Comparison of this drilling performance indicator was used in both the RWD and the conventional drilling assembly to analyze the effect of RWD. Based on the results, with increasing the distance between the pilot bit and reamer, there is an increase in improvement of drilling performance in terms of MSE reduction. The best drilling performance indicator (MSE reduction of 84%) was observed with the distance between the pilot bit and the reamer of 43.3 cm. This is considered a novel finding in reaming while drilling.

THE INFLUENCE OF FRICTION FORCES ON LONGITUDINAL WAVE PROPAGATION IN A STUCK DRILL STRING IN A BOREHOLE

Tribologia ◽  
2018 ◽  
Vol 282 (6) ◽  
pp. 79-87
Author(s):  
Yevhen KHARCHENKO ◽  
Andrii HUTYI ◽  
Volodymyr HAIDUK
Keyword(s):  
Oil And Gas ◽  
Drill Pipe ◽  
Computer Software ◽  
Drill String ◽  
The Body ◽  
Friction Forces ◽  
Impact Mechanism ◽  
Drilling Rig ◽  
Longitudinal Wave Propagation ◽  
The Impact

A mathematical model and the computer software for the analysis of dynamic processes occurring in the drilling pipes in the borehole under stuck drill string release by means of an impact mechanism (a jerking device) or a pulse-wave installation, equipped with electric linear pulse motor are presented. The drill string with an impact mechanism, which is inserted over the stuck section after failure, is detected and is activated by lowering and taking the non-stuck upper part of the string by means of the drilling rig drive and is considered as a discrete-continuous mechanical system. As a result of the impact of the hammer on the body of the impact mechanism, wave processes are formed in the drill string, which helps to release the stuck drill string. The influence of friction forces on propagation of longitudinal waves in the drill pipe string is investigated. Practical recommendations are developed regarding the above-mentioned efficiency of drilling for oil and gas.

Study of the Influence of Shale Anisotropy Orientation on Directional Drilling Performance in Shale

2017 ◽  
Author(s):  
Abdelsalam N. Abugharara ◽  
Charles A. Hurich ◽  
John Molgaard ◽  
Stephen D. Butt
Keyword(s):  
Depth Of Cut ◽  
Directional Drilling ◽  
Laboratory Procedure ◽  
Drilling Rig ◽  
Drilling Performance ◽  
Mechanical Measurements ◽  
Different Types ◽  
Pdc Bit ◽  
Weight On Bit ◽  
Shale Anisotropy

The influence of shale anisotropy orientation on shale drilling performance has been studied using a new laboratory procedure. This procedure includes drilling and testing three sets of shale samples in different orientations from a single rock sample. Shale samples of different types were collected from outcrops located at Conception Bay South (CBS) in Newfoundland, Canada. For predrilling tests, oriented physical and mechanical measurements on each type of shale were conducted on the same rocks that will be drilled later. For drilling tests, three sets of tests were conducted. Each set was in a different orientation, corresponding to those in the physical and mechanical measurements. Each set was conducted under the same drilling parameters of pressure, flow rate (FR), and weight on bit (WOB) using a fully instrumented laboratory scale drilling rig. Two different types of drill bits were used, including a 35 mm dual cutter PDC bit and a 25.4 mm diamond coring bit. The drilling data was analyzed by constructing relationships between drilling rate of penetration (ROP) versus orientation (i.e. 0°, 45°, or 90°). The analysis also included relationships between WOB and bit cutter Depth of Cut (DOC), Revolution Per Minute (RPM), and Torque (TRQ). All the above relations were evaluated as a function of shale bedding orientation. This evaluation can assist in understanding the influence of shale anisotropy on oriented drilling. Details of the conducted tests and results are reported.

Experimental Investigation of the Effect of Shale Anisotropy Orientation on the Main Drilling Parameters Influencing Oriented Drilling Performance in Shale

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
A. N. Abugharara ◽  
Bashir Mohamed ◽  
C. Hurich ◽  
J. Molgaard ◽  
S. D. Butt
Keyword(s):  
Drilling Fluid ◽  
Polycrystalline Diamond ◽  
Bedding Plane ◽  
Depth Of Cut ◽  
Fine Aggregate ◽  
Drilling Rig ◽  
Drilling Performance ◽  
Bedding Planes ◽  
Weight On Bit ◽  
Shale Anisotropy

The influence of shale anisotropy and orientation on shale drilling performance was studied with an instrumented laboratory drilling rig with a 38.1-mm dual-cutter polycrystalline diamond compact (PDC) bit, operating at a nominally fixed rotational speed with a constant rate of flow of drilling fluid—water. However, the rate of rotation (rpm) was affected by the weight on bit (WOB), as was the torque (TRQ) produced. The WOB also affected the depth of cut (DOC). All these variables, WOB, rpm, TRQ, and DOC, were monitored dynamically, for example, rpm with a resolution of one-third of a revolution (samples at time intervals of 0.07 s.) The shale studied was from Newfoundland and was compared with similar tests on granite, also from a local site. Similar tests were also conducted on the concrete made with fine aggregate, used as “rock-like material” (RLM). The shale samples were embedded (laterally confined) in the concrete while drilled in directions perpendicular, parallel, and at 45 deg orientations to bedding planes. Cores were produced from all three materials in several directions for the determination of oriented physical properties derived from ultrasonic testing and oriented unconfined compressive strength (OUCS). In the case of shale, directions were set relative to the bedding. In this study, both primary (or compression) velocity Vp and shear ultrasonic velocity Vs were found to vary with orientation on the local shale samples cored parallel to bedding planes, while Vp and Vs varied, but only slightly, with orientation in tests on granite and RLM. The OUCS data for shale, published elsewhere, support the OUCS theory of this work. The OUCS is high perpendicular and parallel to shale bedding, and is low oblique to shale bedding. Correlations were found between the test parameters determined from the drilling tests on local shale. As expected, ROP, DOC, and TRQ increase with increasing WOB, while there are inverse relationships between ROP, DOC, and TRQ with rpm on the other hand. All these parameters vary with orientation to the bedding plane.

scholarly journals Fractional-order controllers for stick-slip vibration mitigation in oil well drill-strings

2021 ◽  
pp. 146134842098404
Author(s):  
Massinissa Derbal ◽  
Mohamed Gharib ◽  
Shady S Refaat ◽  
Alan Palazzolo ◽  
Sadok Sassi
Keyword(s):  
Fractional Order ◽  
Degrees Of Freedom ◽  
Lumped Parameter Model ◽  
Oil Well ◽  
Proportional Integral Derivative ◽  
Stick Slip ◽  
Proportional Integral ◽  
Drilling Performance ◽  
Weight On Bit ◽  
Rotary Speed

Drillstring–borehole interaction can produce severely damaging vibrations. An example is stick–slip vibration, which negatively affects drilling performance, tool integrity and completion time, and costs. Attempts to mitigate stick–slip vibration typically use passive means and/or change the operation parameters, such as weight on bit and rotational speed. Automating the latter approach, by means of feedback control, holds the promise of quicker and more effective mitigation. The present work presents three separate fractional-order controllers for mitigating drillstring slip–stick vibrations. For the sake of illustration, the drillstring is represented by a torsional vibration lumped parameter model with four degrees of freedom, including parameter uncertainty. The robustness of these fractional-order controllers is compared with traditional proportional-integral-derivative controllers under variation of the weight on bit and the drill bit’s desired rotary speed. The results confirm the proposed controllers effectiveness and feasibility, with rapid time response and less overshoot than conventional proportional-integral-derivative controllers.

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