Life Models for Small-Diameter Polycrystalline Diamond Compact Bits in Hard Abrasive Media

1986 ◽  
Vol 108 (4) ◽  
pp. 310-314
Author(s):  
C. L. Hough ◽  
B. Das ◽  
T. G. Rozgonyi
Keyword(s):  
Cutting Speed ◽  
Small Diameter ◽  
Polycrystalline Diamond ◽  
Prediction Equation ◽  
Logarithmic Model ◽  
Drill Bits ◽  
Rate Versus ◽  
Rotary Speed ◽  
Bit Life ◽  
Polycrystalline Diamond Compact

Mathematical models for bit life of polycrystalline diamond compact (PDC) drill bits were developed for drilling small holes in hard abrasive media. Based on the wear-out criterion of an average 0.060 in. (1.5 mm) flank wear land, bit life equations were formulated in three forms: bit life versus rotary speed and feed rate, bit life versus rotary speed and penetration rate, and wear rate versus cutting speed and cutter engagement area. The traditional linear-logarithmic model proved inadequate to describe bit life, whereas the quadratic-logarithmic model provided the best bit life prediction equation. Consequently, it would be possible to predict the optimum economical drilling conditions more accurately by employing a quadratic-logarithmic based bit life equation. The equation demonstrated the ability to predict the bit life precisely under different modes of wear.

Wear Characteristics of Polycrystalline Diamond Compact Drill Bits in Small Diameter Rock Drilling

1985 ◽  
Vol 107 (4) ◽  
pp. 534-542 ◽  
Author(s):  
C. L. Hough ◽  
B. Das
Keyword(s):  
Small Diameter ◽  
Polycrystalline Diamond ◽  
Wear Test ◽  
Test Results ◽  
Failure Characteristics ◽  
Wear Characteristics ◽  
Drill Bits ◽  
Rotary Speed ◽  
Polycrystalline Diamond Compact ◽  
Single Material

The wear characteristics of polycrystalline diamond compact (PDC) drill bits were investigated in the context of drilling small holes in a hard abrasive medium. An efficient method for measuring wear of the PDC drill bits was developed. The wear test results were grouped or categorized in terms of rotary speed, feed and wear or failure characteristics. Contrary to the three classical wear phases (break-in, uniform wear and rapid breakdown) of the single material cutters, four distinctive wear phases were formed for the PDC cutters: I–break-in, II–diamond wear, III–carbide wear, and IV–rapid breakdown. The characteristics of the wear phases were identified and some suggestions were made to alleviate the wear problem.

Mathematical Modeling of PDC Bit Drilling Process Based on a Single-Cutter Mechanics

1993 ◽  
Vol 115 (4) ◽  
pp. 247-256 ◽  
Author(s):  
A. K. Wojtanowicz ◽  
E. Kuru
Keyword(s):  
Polycrystalline Diamond ◽  
Rock Properties ◽  
Drilling Process ◽  
Drilling Parameters ◽  
Pdc Bit ◽  
Analytical Development ◽  
Assumed Similarity ◽  
Balance Of Forces ◽  
Bit Life ◽  
Polycrystalline Diamond Compact

An analytical development of a new mechanistic drilling model for polycrystalline diamond compact (PDC) bits is presented. The derivation accounts for static balance of forces acting on a single PDC cutter and is based on assumed similarity between bit and cutter. The model is fully explicit with physical meanings given to all constants and functions. Three equations constitute the mathematical model: torque, drilling rate, and bit life. The equations comprise cutter’s geometry, rock properties drilling parameters, and four empirical constants. The constants are used to match the model to a PDC drilling process. Also presented are qualitative and predictive verifications of the model. Qualitative verification shows that the model’s response to drilling process variables is similar to the behavior of full-size PDC bits. However, accuracy of the model’s predictions of PDC bit performance is limited primarily by imprecision of bit-dull evaluation. The verification study is based upon the reported laboratory drilling and field drilling tests as well as field data collected by the authors.

scholarly journals Application of an innovative ridge-ladder-shaped polycrystalline diamond compact cutter to reduce vibration and improve drilling speed

2020 ◽  
Vol 103 (3) ◽  
pp. 003685042093097
Author(s):  
Dou Xie ◽  
Zhiqiang Huang ◽  
Yuqi Yan ◽  
Yachao Ma ◽  
Yuan Yuan
Keyword(s):  
Oil And Gas ◽  
Polycrystalline Diamond ◽  
Rock Breaking ◽  
Drilling Process ◽  
Drilling Speed ◽  
Stick Slip ◽  
Gas Drilling ◽  
Drill Bits ◽  
Element Simulation ◽  
Polycrystalline Diamond Compact

Polycrystalline diamond compact bits have been widely used in the Oil and Gas drilling industry, despite the fact that they may introduce undesired vibration into the drilling process, for example, stick-slip and bit bounce, which accelerate the failure rate and lead to higher drilling costs. First, we develop an innovative ridge-ladder-shaped polycrystalline diamond compact cutter, which has ridge-shaped cutting faces and multiple cutting edges with stepped distribution, in the hope of reducing vibration and improving drilling speed. Then, the scrape tests of ridge-ladder-shaped and general polycrystalline diamond compact cutters are carried out in a laboratory, indicating that the cutting, lateral, and longitudinal forces on ridge-ladder-shaped polycrystalline diamond compact cutters are smaller and with minor fluctuations. Due to different rock-breaking mechanisms, ridge-ladder-shaped polycrystalline diamond compact cutters have higher cutting efficiency compared to general polycrystalline diamond compact cutters, which is also verified experimentally. Finally, the drilling characteristics of a new polycrystalline diamond compact bit fitted with some ridge-ladder-shaped polycrystalline diamond compact cutters are compared to those of a general polycrystalline diamond compact bit by means of finite element simulation. The results show that introducing ridge-ladder-shaped polycrystalline diamond compact cutters can not only reduce the stick-slip vibration, bit bounce, and backward rotation of drill bits effectively, but also improve their rate of penetration.

The Effect of Back Rake Angle on the Performance of Small-Diameter Polycrystalline Diamond Rock Bits: ANOVA Tests

1986 ◽  
Vol 108 (4) ◽  
pp. 305-309 ◽  
Author(s):  
C. L. Hough
Keyword(s):  
Specific Energy ◽  
Statistical Difference ◽  
Penetration Rate ◽  
Small Diameter ◽  
Polycrystalline Diamond ◽  
Rake Angle ◽  
Performance Criteria ◽  
Maximum Penetration ◽  
Rotary Speed ◽  
Selection Of

The effect of back rake angle on a center vacuum bit design was investigated through factorial Analysis of Variance (ANOVA) tests for drilling in shale. Multiple performance criteria: penetration rate, specific energy and torque were used in these tests. Thrust and rotary speed were the controlled variables. Results from ANOVA tests showed that rake angle has a significant effect on penetration rate and torque but not on specific energy. Further tests of means revealed that the 20-deg bit gave the maximum penetration rate although there was no statistical difference among the 15, 20 and 25-deg angles. Tests of means also revealed that the 7-deg bit gives the minimum torque, but is statistically the same as the 15 and 25-deg bits. The results of the test will be useful for design and selection of small-diameter bits for drilling in shale and sand formations.

Low Invasion Corehead Reduces Mud Invasion While Improving Performances

1994 ◽  
Vol 116 (4) ◽  
pp. 258-267
Author(s):  
G. M. Clydesdale ◽  
A. Leseultre ◽  
E. Lamine
Keyword(s):  
Flow Visualization ◽  
High Speed ◽  
Drilling Fluid ◽  
Polycrystalline Diamond ◽  
Design Flow ◽  
Rate Of Penetration ◽  
The Core ◽  
Drill Bits ◽  
Hydraulic Design ◽  
Bit Life

A corehead was designed, manufactured and tested to reduce fluid invasion of the core. This is obtained by minimizing the exposure time of the core to the drilling fluid in increasing the rate of penetration (ROP). The design incorporates a medium heavyset polycrystalline diamond compact (PDC) cutting structure developed in accordance with cutting models and balancing methods used for drill bits. The highest ROP is achieved by a particular hydraulic design: flow ports shape and positioning to clean the cutting structure enhance the drilled cuttings removal while preventing drilling fluid in the throat of the corehead. Moreover, an internal lip works with a special inner barrel shoe to effectively seal off mud flow from the throat. All the design features have been subjected to laboratory tests, including measurement of pressure drop across the corehead and flow visualization studies. Flow visualization tests include high-speed filming of the flow and paint tracing to indicate the special flow pattern. In conjunction with lab tests, a numerical simulation was performed using fluid dynamics software to optimize hydraulic parameters. The low invasion core bit has been used in numerous applications. The performance achieved was significantly better than the average achieved over a period of years using various PDC coreheads. The rate of penetration was increased by a factor of 4.8 and bit life by 2.3 (often with reusable condition).

Dynamical Analysis of Drill Bit With Ultrasonic Vibration

2015 ◽  
Author(s):  
Dapeng Zhao ◽  
Sigbjørn Sangesland
Keyword(s):  
Ultrasonic Vibration ◽  
Reaction Force ◽  
Polycrystalline Diamond ◽  
Dynamical Analysis ◽  
Contact Friction ◽  
Rock Interaction ◽  
Drill Bits ◽  
Mass Spring Model ◽  
Mass Spring ◽  
Polycrystalline Diamond Compact

Based on the bit-rock interaction laws, a simple nonlinear 2-dofs mass-spring model is developed to analyze the dynamic cutting process with normal ultrasonic vibration excitation. The study presents a single cutter used in Polycrystalline-Diamond-Compact (PDC) drill bits. Using the 4th Runge-Kutta’s algorithm, numerical simulation found that ultrasonic vibration-induced contact deflection and even loss of contact. The contact friction between the rock and wear-flat (wear surface), which relates to the reaction force, is therefore reduced. This will reduce the wear on the cutter and the force needed to cut the rock. This indicates that the average reduction of friction induced by ultrasonic vibration can be explained by decreasing the average normal force on the cutter-rock wear-flat, rather than changing the friction coefficient.

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