DRILL BIT SEISMIC—DRILLING OPTIMISATION CASE STUDY: CRUX–1

2001 ◽  
Vol 41 (1) ◽  
pp. 623
Author(s):  
H. Cao ◽  
Y. Kurata
Keyword(s):  
Real Time ◽  
Cost Savings ◽  
Drill String ◽  
Acoustic Energy ◽  
Depth Information ◽  
Drilling Process ◽  
Drill Bit ◽  
Travel Times ◽  
Velocity Information

Drill Bit Seismic (DBSeis) technique utilises the acoustic energy generated during the drilling process to provide vital information about the subsurface structure. This information, produced in real time at the wellsite, is used to optimise the drilling process, leading to significant cost savings and enhanced safety.When a working drill bit destroys the rock at the bottom of the hole, it radiates acoustic energy into the surrounding formation. This acoustic energy is recorded by sensors both at the top of the drill-string and placed on the sea floor in the vicinity of the rig. Travel times recorded by the sensors on the ground are corrected for drill-string travel times to provide the time-depth information. This accurate time-depth information can then be used to continuously update the depth of drilling hazards by converting the surface seismic markers from time into depth domain.After experiencing excessive loss of circulation in the Johnson Formation in a nearby well, DBSeis was run in the Crux–1 well to help predict the depth of the top Johnson Formation while drilling to the 13 3/8” casing shoe depth. The well program called for the casing shoe to be set as close to, but above this formation. The two way time of the Johnson formation had been estimated from the surface seismic to be 0.994 s. DBSeis was used to provide real time time-depth information to convert the two way time to depth.The estimated top Johnson Formation at 0.994 s two way time (TWT) corresponded to a depth of 1,231 m SS using pre-drill velocity information. Using the DBSeis time-depth data, this depth was reduced to 1,192 m SS and the casing shoe was set at 1,164 m SS. The actual depth of the top Johnson Formation was later estimated at 1,178 m SS from ROP/WOB.

Study of stick–slip suppression and robustness to parametric uncertainty in drill strings containing torsional vibration tool using sliding-mode control

2021 ◽  
pp. 146441932110452
Author(s):  
Jialin Tian ◽  
Jie Wang ◽  
Siqi Zhou ◽  
Yinglin Yang ◽  
Liming Dai
Keyword(s):  
Torsional Vibration ◽  
Complex Dynamics ◽  
Sliding Mode ◽  
Parametric Uncertainty ◽  
Drill String ◽  
Lumped Parameter Model ◽  
Drilling Process ◽  
Drill Bit ◽  
Stick Slip ◽  
Drilling Operations

Excessive stick–slip vibration of drill strings can cause inefficiency and unsafety of drilling operations. To suppress the stick–slip vibration that occurred during the downhole drilling process, a drill string torsional vibration system considering the torsional vibration tool has been proposed on the basis of the 4-degree of freedom lumped-parameter model. In the design of the model, the tool is approximated by a simple torsional pendulum that brings impact torque to the drill bit. Furthermore, two sliding mode controllers, U1 and U2, are used to suppress stick–slip vibrations while enabling the drill bit to track the desired angular velocity. Aiming at parameter uncertainty and system instability in the drilling operations, a parameter adaptation law is added to the sliding mode controller U2. Finally, the suppression effects of stick–slip and robustness of parametric uncertainty about the two proposed controllers are demonstrated and compared by simulation and field test results. This paper provides a reference for the suppression of stick–slip vibration and the further study of the complex dynamics of the drill string.

Torsional Vibrations and Nonlinear Dynamic Characteristics of Drill Strings and Stick-Slip Reduction Mechanism

2019 ◽  
Vol 14 (8) ◽  
Author(s):  
Jialin Tian ◽  
Genyin Li ◽  
Liming Dai ◽  
Lin Yang ◽  
Hongzhi He ◽  
...  
Keyword(s):  
Torsional Vibration ◽  
Nonlinear Dynamic ◽  
Drill String ◽  
Drilling Process ◽  
Drill Bit ◽  
Torsional Vibrations ◽  
Reduction Mechanism ◽  
Nonlinear Dynamic Model ◽  
Stick Slip ◽  
Research Results

Torsional stick–slip vibrations easily occur when the drill bit encounters a hard or a hard-soft staggered formation during drilling process. Moreover, serious stick–slip vibrations of the drill string is the main factor leading to low drilling efficiency or even causing the downhole tools failure. Therefore, establishing the stick–slip theoretical model, which is more consistent with the actual field conditions, is the key point for new drilling technology. Based on this, a new torsional vibration tool is proposed in this paper, then the multidegree-of-freedom torsional vibrations model and nonlinear dynamic model of the drill string are established. Combined with the actual working conditions in the drilling process, the stick–slip reduction mechanism of the drill string is studied. The research results show that the higher rotational speed of the top drive, smaller viscous damping of the drill bit, and smaller WOB (weight on bit) will prevent the stick–slip vibration to happen. Moreover, the new torsional vibration tool has excellent stick–slip reduction effect. The research results and the model established in this paper can provide important references for reducing the stick–slip vibrations of the drill string and improving the rock-breaking efficiency.

Real-Time Software to Estimate Friction Coefficient and Downhole Weight on Bit During Drilling of Horizontal Wells

2014 ◽  
Author(s):  
Mazeda Tahmeen ◽  
Geir Hareland ◽  
Bernt S. Aadnoy
Keyword(s):  
Friction Coefficient ◽  
Real Time ◽  
Information Transfer ◽  
Horizontal Wells ◽  
Drill String ◽  
Surface Measurement ◽  
Drilling Process ◽  
Drilling Data ◽  
Weight On Bit ◽  
Drag Analysis

The increasing complexity and higher drilling cost of horizontal wells demand extensive research on software development for the analysis of drilling data in real-time. In extended reach drilling, the downhole weight on bit (WOB) differs from the surface seen WOB (obtained from on an off bottom hookload difference reading) due to the friction caused by drill string movement and rotation in the wellbore. The torque and drag analysis module of a user-friendly real-time software, Intelligent Drilling Advisory system (IDAs) can estimate friction coefficient and the effective downhole WOB while drilling. IDAs uses a 3-dimensional wellbore friction model for the analysis. Based on this model the forces applied on a drill string element are buoyed weight, axial tension, friction force and normal force perpendicular to the contact surface of the wellbore. The industry standard protocol, WITSML (Wellsite Information Transfer Standard Markup Language) is used to conduct transfer of drilling data between IDAs and the onsite or remote WITSML drilling data server. IDAs retrieves real-time drilling data such as surface hookload, pump pressure, rotary RPM and surface WOB from the data servers. The survey data measurement for azimuth and inclination versus depth along with the retrieved drilling data, are used to do the analysis in different drilling modes, such as lowering or tripping in and drilling. For extensive analysis the software can investigate the sensitivity of friction coefficient and downhole WOB on user-defined drill string element lengths. The torque and drag analysis module, as well as the real-time software, IDAs has been successfully tested and verified with field data from horizontal wells drilled in Western Canada. In the lowering mode of drilling process, the software estimates the overall friction coefficient when the drill bit is off bottom. The downhole WOB estimated by the software is less than the surface measurement that the drillers used during drilling. The study revealed verification of the software by comparing the estimated downhole WOB with the downhole WOB recorded using a downhole measuring tool.

scholarly journals Real-Time Minimization of Mechanical Specific Energy with Multivariable Extremum Seeking

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1298
Author(s):  
Magnus Nystad ◽  
Bernt Sigve Aadnøy ◽  
Alexey Pavlov
Keyword(s):  
Real Time ◽  
Specific Energy ◽  
Optimization Method ◽  
Initial Guess ◽  
Drill String ◽  
Extremum Seeking ◽  
Drilling Process ◽  
Field Development ◽  
Mechanical Specific Energy ◽  
Time Minimization

Drilling more efficiently and with less non-productive time (NPT) is one of the key enablers to reduce field development costs. In this work, we investigate the application of a data-driven optimization method called extremum seeking (ES) to achieve more efficient and safe drilling through automatic real-time minimization of the mechanical specific energy (MSE). The ES algorithm gathers information about the current downhole conditions by performing small tests with the applied weight on bit (WOB) and drill string rotational rate (RPM) while drilling and automatically implements optimization actions based on the test results. The ES method does not require an a priori model of the drilling process and can thus be applied even in instances when sufficiently accurate drilling models are not available. The proposed algorithm can handle various drilling constraints related to drilling dysfunctions and hardware limitations. The algorithm’s performance is demonstrated by simulations, where the algorithm successfully finds and maintains the optimal WOB and RPM while adhering to drilling constraints in various settings. The simulations show that the ES method is able to track changes in the optimal WOB and RPM corresponding to changes in the drilled formation. As demonstrated in the simulation scenarios, the overall improvements in rate of penetration (ROP) can be up to 20–170%, depending on the initial guess of the optimal WOB and RPM obtained from e.g., a drill-off test or a potentially inaccurate model. The presented algorithm is supplied with specific design choices and tuning considerations that facilitate its simple and efficient use in drilling applications.

Data Exchange and Collaboration Realize Automated Drilling Control Potential

2021 ◽  
Vol 73 (02) ◽  
pp. 47-48
Author(s):  
Judy Feder
Keyword(s):  
Real Time ◽  
Data Exchange ◽  
Data Transfer ◽  
Cost Savings ◽  
Technical Conference ◽  
Full Potential ◽  
Drilling Process ◽  
Real Process ◽  
Significant Cost Reduction ◽  
Technical Discussion

This article, written by JPT Technology Editor Judy Feder, contains highlights of paper SPE 201763, “Exploiting the Full Potential in Automated Drilling Control by Increased Data Exchange and Multidisciplinary Collaboration,” by Kristian Gjerstad, SPE, and Ronny Bergerud, Sekal, and Stig Tore Thorsen, SPE, Equinor, prepared for the 2020 SPE Annual Technical Conference and Exhibition, originally scheduled to be held in Denver, Colorado, 5-7 October. The paper has not been peer reviewed. The complete paper describes challenges that must be overcome to reach the goal of drilling systems automation (DSA). The authors explore steps necessary to realize the full potential of performance-enhancing functionalities in automated drilling control (ADC) software, highlight current gaps, and present relatively easily achievable goals that can enable significant cost reduction and improvements in automation and safety. They also emphasize that automation is a multidisciplinary task, and that success requires collaboration between different sectors of the drilling industry. Overview The 19-page complete paper includes detailed technical discussion of topics ranging from the basic principles of an ADC system and practical challenges experienced with a model-based digital twin approach to suggested solutions and improvements. Each topic is divided into numerous related discussions. Because delving into each of these discussions is not possible in this synopsis, these have been outlined, with a few supporting points included for each. The Potential of ADC Systems Dedicated software applications - referred to by the authors as ADC systems - for protecting the well, increasing safety, automating repetitive operations, and optimizing the drilling process, have been available for some time. Several projects in which sophisticated ADC systems evaluate downhole conditions to assist the driller with judgments and decisions have been reported, with promising results including noticeable improvements in cost savings, reduced incidents, and improved safety. However, the number of rigs with sophisticated ADC systems running actively in real time is not high, and even on rigs where an ADC system is in use, the potential of the system generally is not fully leveraged. One reason is that these ADC systems are based on models of the drilling process running in parallel with the real process, with each requiring the exact same inputs in real time to work optimally. Many of these inputs are entered manually because the instrumentation, equipment, and infrastructure needed to automate the data transfer are not in place. The inputs that are automated may not be sufficiently accurate or reliable, so manual interactions are needed. Experience shows that even on relatively new rigs with modern instrumentation, a large untapped potential exists. An underlying reason for this lack of automated inputs is that different parties involved in establishing the required instrumentation and automated signal transfer are not well aligned. Thus, increased automation and repeatability can introduce increased staffing and cost for operating the ADC system. To overcome this paradox, better collaboration is required among the vendors in the complete production loop.

On the Importance of the Coupling Between Transient Mechanical, Hydraulic and Thermal Effects for the Modelling of Real-Time Drilling Operations

2019 ◽  
Author(s):  
Erik Wolden Dvergsnes ◽  
Eric Cayeux
Keyword(s):  
Real Time ◽  
Drilling Fluid ◽  
Mass Density ◽  
Thermal Conditions ◽  
Time Discretization ◽  
Drill String ◽  
Drilling Process ◽  
Drilling Operation ◽  
Improved Performance ◽  
Transient Models

Abstract Because of the increased importance for the drilling industry to deliver drilling automation solutions, model-based applications for the analysis and control of the drilling process, have become an attractive approach towards improved performance and increased safety. A critical characteristic for such applications is its ability to perform accurate simulations of the drilling operation in real-time, based on a detailed description of the wellbore. In a real-time context, the boundary conditions of the drilling system are seldom constant, therefore reinforcing the importance of utilizing transient models of the drilling process instead of steady state ones. Typical domains that require modelling are related to the mechanical, hydraulic and heat transfer aspects of a drilling operation. The time constants of the force-, momentum-, mass- and energy-conservation equations are sufficiently different to allow for solving each of these equations with different time discretization schemes. Yet, side effects influence the results from each other’s and therefore a time coupling shall nevertheless be accounted for. For instance, for a drilling operation conducted on a floater, the heave induced movement at the top of the string propagates along the drill-string, therefore causing a displacement that induces swab and surge pressure variations, which themselves generate counter-acting forces on the drill-string. In such conditions, both the mechanical and hydraulic frictions generate heat that changes the in situ thermal conditions and therefore the drilling fluid mass density and its rheological behavior. Consequently, heat exchange caused by the drill-string and fluid movements also influences the hydraulic response of the system. Furthermore, thermal expansion will also apply to the drill-string. In this paper, we discuss recent advances related to the coupling between transient mechanical, hydraulic and thermal models, where a key criterion is that the combined drilling model shall be capable of running in real-time on a standard computer. Incorporating these transient models is considered a necessary step towards improved accuracy of simulations, especially on floaters, where heave effects become important. We illustrate various effects by presenting and discussing several simulations results in detail.

Minimising Torsional Vibration Due to Stick Slip Using Z Technology for Drilling Energy Efficiency in Multiple Hard Stringers Field in Offshore Malaysia

2021 ◽  
Author(s):  
Mohamad Haikal Nordin ◽  
Lai Keng Looi ◽  
Pete Slagel ◽  
Mohamad Hafiz Othman ◽  
Abdul Razak Affandi ◽  
...  
Keyword(s):  
Torsional Vibration ◽  
Drill Pipe ◽  
Cost Savings ◽  
Wide Band ◽  
Static Friction ◽  
Drill String ◽  
Drill Bit ◽  
Stick Slip ◽  
Pull Out ◽  
Phase 1B

Abstract Field T is well known with its multiple layers of hard stringers that can go up to 25 ksi UCS at certain intervals, predominantly in 12-1/4" and 8-1/2" hole section. This can lead to stick-slip problem whereby the drill bit momentarily stalls due to high static friction, while the drill string keeps rotating. As a result, torque will buildup in pipe until it overcomes the friction at the bit, resulting in the drill pipe unwinding itself. Over time, this issue results in reduced drilling efficiency (i.e. lower ROP), eventually causing damage to the bit or worse, twisting off the BHA, which translates into high cost exposure to the Operator. During the exploration phase, the Operator required on average, 4 to 7 bit trips to drill 12-1/4" hole section and 2 to 4 trips were required to drill 8-1/2" hole section. The most reported reason to pull out of the hole were, BHA change out, downhole tool failure (DTF) and low rate of penetration (ROP). The bits’ inner & outer cutters were also reported to be damaged with dull grading as high as wear value of 7 or 8. Z technology is a torsional vibration mitigation system that uses wide band impedance (Z) matching concept that aims to absorb all torque waves arriving at top drive by overcoming inertia of motor & gearbox. The Z Technology changes the conventional hard boundary condition of a standard top drive (TD) RPM controller that is "stiff" (constant RPM) which results in full reflection of all torsional waves. A "stiff" TD control system leads to growth of standing waves (A combination of TD constant RPM & stick-slip "unwind" RPM) in the string which eventually may lead to torsional vibrations to the drill bit and/or motor housing/BHA. While drilling Development Phase 1B, Z Technology was seen to be effective in mitigating stick-slip. As a result, more mechanical specific energy (MSE) was available to be transmitted to the bit for formation rock removal. All three wells in the Phase 1B campaign managed to achieve the highest ROP in T field. This translated into cost savings in rig time and cost avoidance to Operator due to BHA damage. The paper will discuss the details of the Z Technology mechanism, its implementation and evaluating its effectiveness in minimizing torsional vibration due to the stick-slip issue.

A Tool for Derivation of Real Time Lithological Information from Drill Bit Sound

2021 ◽  
Author(s):  
Yunlai Yang ◽  
Wei Li ◽  
Fahd A. Almalki ◽  
Maher I. Almarhoon
Keyword(s):  
Real Time ◽  
Sound Transmission ◽  
Field Trials ◽  
Drill String ◽  
Drive Shaft ◽  
Drill Bit ◽  
Acoustic Sensors ◽  
Preliminary Results ◽  
Drilling Operations ◽  
Real Time Applications

Abstract Real time lithological information at the drill bit is required for some important drilling operations, such as geo-steering and casing shoe positioning. This paper presents a novel tool "Petro-phone" for recording and processing drill bit sounds, which are generated by the drill bit cutting the rock, in order to provide real time lithological information for the rock at the drill bit. A prototype and a preliminary professional version of Petro-phone have been developed and field trialed. Petro-phone is a surface tool with its acoustic sensors attached to the top drive of a drill rig at some strategical locations for maximally picking up drill bit sounds. The drill bit sounds generated at the drill bit transmit along drill string and drive shaft to reach to the acoustic sensors. Since all the parts along the drill bit sound transmission pathway are made of steel, the drill bit sounds transmit efficiently from the source (drill bit) to the sensors. Preliminary results from two field trials show that drill bit sound patterns correlate with lithologies. The results also indicate that a parameter "Apparent Power" of drill bit sounds negatively correlates with gamma log. Due to its true real time nature, Petro-phone potentially has some real time applications, such as geo-steering, casing shoes positioning. Recorded drill bit sound can also potentially be used to derive lithological information, such as lithology type.

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