To the problem of calculation of the drill string lower part assemblies for preventing borehole deviation

The paper gives a methodology for calculating the drill string performance under off-design conditions, including the passage through the interface separating rocks with very different physico-mechanical characteristics, drilling of boulder rocks, and dynamic modes of operation. One of the mechanisms of the destruction of drill string elements and roller cutters is revealed.

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Application of the piecewise constant method in nonlinear dynamics of drill string

International Journal of Nonlinear Sciences and Numerical Simulation ◽

10.1515/ijnsns-2019-0167 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Jialin Tian ◽

Jie Wang ◽

Yi Zhou ◽

Lin Yang ◽

Changyue Fan ◽

...

Keyword(s):

Nonlinear Dynamics ◽

Dynamic Model ◽

Dynamic Characteristics ◽

Drill String ◽

Vibration Velocity ◽

Kutta Method ◽

Time Step ◽

Piecewise Constant ◽

Runge Kutta Method ◽

Runge Kutta

Abstract Aiming at the current development of drilling technology and the deepening of oil and gas exploration, we focus on better studying the nonlinear dynamic characteristics of the drill string under complex working conditions and knowing the real movement of the drill string during drilling. This paper firstly combines the actual situation of the well to establish the dynamic model of the horizontal drill string, and analyzes the dynamic characteristics, giving the expression of the force of each part of the model. Secondly, it introduces the piecewise constant method (simply known as PT method), and gives the solution equation. Then according to the basic parameters, the axial vibration displacement and vibration velocity at the test points are solved by the PT method and the Runge–Kutta method, respectively, and the phase diagram, the Poincare map, and the spectrogram are obtained. The results obtained by the two methods are compared and analyzed. Finally, the relevant experimental tests are carried out. It shows that the results of the dynamic model of the horizontal drill string are basically consistent with the results obtained by the actual test, which verifies the validity of the dynamic model and the correctness of the calculated results. When solving the drill string nonlinear dynamics, the results of the PT method is closer to the theoretical solution than that of the Runge–Kutta method with the same order and time step. And the PT method is better than the Runge–Kutta method with the same order in smoothness and continuity in solving the drill string nonlinear dynamics.

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Kinematics and dynamics analysis of new rotary-percussive PDM drilling tool

Journal of Low Frequency Noise Vibration and Active Control ◽

10.1177/1461348421989156 ◽

2021 ◽

pp. 146134842198915

Author(s):

Jialin Tian ◽

Xuehua Hu ◽

Liming Dai ◽

Lin Yang ◽

Yi Yang ◽

...

Keyword(s):

Drill String ◽

Structure Design ◽

Drilling Process ◽

Analysis Model ◽

Drilling Tool ◽

Stick Slip ◽

Rate Of Penetration ◽

Bottom Hole ◽

Bottom Hole Assembly ◽

The Impact

This paper presents a new drilling tool with multidirectional and controllable vibrations for enhancing the drilling rate of penetration and reducing the wellbore friction in complex well structure. Based on the structure design, the working mechanism is analyzed in downhole conditions. Then, combined with the impact theory and the drilling process, the theoretical models including the various impact forces are established. Also, to study the downhole performance, the bottom hole assembly dynamics characteristics in new condition are discussed. Moreover, to study the influence of key parameters on the impact force, the parabolic effect of the tool and the rebound of the drill string were considered, and the kinematics and mechanical properties of the new tool under working conditions were calculated. For the importance of the roller as a vibration generator, the displacement trajectory of the roller under different rotating speed and weight on bit was compared and analyzed. The reliable and accuracy of the theoretical model were verified by comparing the calculation results and experimental test results. The results show that the new design can produce a continuous and stable periodic impact. By adjusting the design parameter matching to the working condition, the bottom hole assembly with the new tool can improve the rate of penetration and reduce the wellbore friction or drilling stick-slip with benign vibration. The analysis model can also be used for a similar method or design just by changing the relative parameters. The research and results can provide references for enhancing drilling efficiency and safe production.

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Prediction of shallow bit position based on vibration signal monitoring of bit broken rock

International Journal of Distributed Sensor Networks ◽

10.1177/1550147721991708 ◽

2021 ◽

Vol 17 (1) ◽

pp. 155014772199170

Author(s):

Jinping Yu ◽

Deyong Zou

Keyword(s):

Acoustic Emission ◽

Time Domain ◽

Vibration Signal ◽

Rock Breaking ◽

Drill String ◽

Mean Square ◽

Drilling Force ◽

Emission Signal ◽

Force Signal ◽

The Mean

The speed of drilling has a great relationship with the rock breaking efficiency of the bit. Based on the above background, the purpose of this article is to predict the position of shallow bit based on the vibration signal monitoring of bit broken rock. In this article, first, the mechanical research of drill string is carried out; the basic changes of the main mechanical parameters such as the axial force, torque, and bending moment of drill string are clarified; and the dynamic equilibrium equation theory of drill string system is analyzed. According to the similarity criterion, the corresponding relationship between drilling process parameters and laboratory test conditions is determined. Then, the position monitoring test system of the vibration bit is established. The acoustic emission signal and the drilling force signal of the different positions of the bit in the process of vibration rock breaking are collected synchronously by the acoustic emission sensor and the piezoelectric force sensor. Then, the denoised acoustic emission signal and drilling force signal are analyzed and processed. The mean value, variance, and mean square value of the signal are calculated in the time domain. The power spectrum of the signal is analyzed in the frequency domain. The signal is decomposed by wavelet in the time and frequency domains, and the wavelet energy coefficients of each frequency band are extracted. Through the wavelet energy coefficient calculated by the model, combined with the mean, variance, and mean square error of time-domain signal, the position of shallow buried bit can be analyzed and predicted. Finally, by fitting the results of indoor experiment and simulation experiment, it can be seen that the stress–strain curve of rock failure is basically the same, and the error is about 3.5%, which verifies the accuracy of the model.

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