RISS 검색 - 국내학술지논문

1
Analysis of mechanical behavior and hysteresis heat generating mechanism of PDM motor

Changshuai Shi,Xiaohua Zhu,Juan Deng,Liping Tang 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.3
Positive displacement motor (PDM), which is prone to high temperature fatigue failure, can be weakened in its application in deep and superdeep well. In order to study the forced state, deformation regularity and thermal hysteresis of PDM motor, the paper established the three-dimensional thermal-mechanical coupled Finite element model (FEM). Based on the theoretical research, experimental study and numerical simulation, the study found that the displacement of stator lining shows a sinusoidal variation under internal pressure, when adapting the general form of sine function to fitting inner contour line deformation function. Then the paper analyzed the hysteresis heat generating mechanism of the motor, learning that hysteresis thermogenous of stator lining occurs due to the viscoelastic of rubber material and cyclic loading of stator lining. A heartburn happens gradually in the center of the thickest part of the stator lining as temperature increases, which means work efficiency and service life of PDM will be decreased when used in deep or superdeep well. In this paper, we established a theory equation for the choice of interference fit and motor linetype optimization design, showing hysteresis heat generating analyzing model and method are reasonable enough to significantly improve PDM’s structure and help better use PDM in deep and surdeep well.
2
Design and analysis of sealed suspension module based on solid expandable tubular repair technology

Xiaohua Zhu,Feilong Cheng,Changshuai Shi,Jia’nan Li,Kailin Chen 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.2
The ability of sealing suspension of solid expandable tubular (SET) is one of the important factors that determine whether pipe can expand normally and serve. To solve the problem that the SET deviates from the original position (causing for the failure to repair of leakage well) due to the insufficient suspension force after expansion, this paper establishes the two-dimensional coupling model of SET-rubber ring-expansion cone-casing based on laboratory experiment parameters, designs the parameters of the sealed suspension rubber ring and conducts simulation. The results show that when the compression amount of the rubber ring is designed to be 47 %-58 % of the rubber thickness, the SET has excellent sealing ability after expansion and can meet the requirements of suspension force; too much compression will affect the service life of the rubber ring. When the length of the rubber ring is 50 mm-110 mm, the driving force and contact pressure during expansion are suitable; the rubber ring spacing is designed to be 110 mm, which avoids interference after rubber compression and saves material. In addition, the vulcanizing bonding strength of the rubber ring should be greater than 120 kN to avoid peeling off due to the failure of the rubber ring and SET bonding. The research results of this paper provide a theoretical basis for the design of sealing suspension module of SET repair technology.
3
Mechanical plugging—solid expandable tubular refracturing technology

Xiaohua Zhu,Feilong Cheng,Changshuai Shi,Kailin Chen 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.6
To solve the three major problems of low production, low efficiency and low permeability of oil fields, it is necessary to develop new tight oil layers or shale oil outside the original perforated section in the well that has been perforated. The key to the success of repeated fracturing operations is the ability to block the original perforation of the well. At present, with tubing fracturing construction, volume fracturing of the target reservoir cannot be achieved due to limited displacement, and the effect of reservoir transformation is not obvious, affecting the productivity of the old well. Based on the above problems, this paper proposes a new blocking method suitable for fracturing wells - solid expansdable tubular (SET) plugging. In this paper, it established SET-expansion cone-casing-rubber ring 2D dynamic model which considers the friction, and contact, to analyze the effect of compression and length of rubber ring and the constraint condition of SET on sealing performance; laboratory experiments were carried out and data on driving force, sealing capacity and suspension force were obtained. The results show that optimizing the parameters of expansion cone structure can effectively reduce the residual stress of SET and driving force after expansion; the construction method of SET and the parameters of rubber ring are the main factors that affect the suspension sealing ability, and paper proposes an effective solution; in addition, experiment results show that the SET meets the requirements of fracturing construction with internal pressure greater than 60 MPa and suspension force greater than 600 kN after expansion, and can be used to seal the well body structure of refracturing wells with fewer perforations and shorter distances, and the diameter can be guaranteed to reach 112 mm. The research results provide new ideas and solutions for repeated pressure wells and high-pressure plugging.
4
Effects of weight on bit on torsional stick-slip vibration of oilwell drill string

Liping Tang,Xiaohua Zhu,Xudong Qian,Changshuai Shi 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.10
The stick-slip phenomenon is a type of dysfunction detrimental to the drilling operation. Field application shows that stick-slip phenomenon is inclined to appear when using a large Weight on bit (WOB). In this paper, effects of the WOB on the stick-slip vibration are investigated. Based on a lumped torsional pendulum model of the drilling system, equation of motion of the drill bit is obtained. By using parameters commonly used in field applications, the bit dynamics are analyzed and the stick-slip vibrations are discussed. During the stick-slip motions, the negative damping effect occurs in the transition from the stick phase to the slip phase. With the increasing WOB, the bit behavior may change from the stable motion to the stick-slip vibration once the WOB reaches the critical value. In case of stickslip vibration, the phase trajectory ultimately converges to a limit cycle which represents periodical bit motion. With increases in the WOB, the limit cycle enlarges. For cases without stick-slip vibrations, the drill bit vibrates damply and finally converges to a state of uniform motion. The results presented in this paper can be applied to interpret some of the field phenomena related to WOB.

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