Relative Significance of Multiple Parameters on the Mechanical Specific Energy and Frictional Responses of Polycrystalline Diamond Compact Cutters

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Babak Akbari ◽  
Stefan Z. Miska
Keyword(s):  
Specific Energy ◽  
Polycrystalline Diamond ◽  
Friction Angle ◽  
Rake Angle ◽  
Fractional Factorial ◽  
Depth Of Cut ◽  
Relative Significance ◽  
Mechanical Specific Energy ◽  
Wellbore Pressure ◽  
Polycrystalline Diamond Compact

A high pressure single polycrystalline diamond compact (PDC) cutter testing facility was used to investigate the effect of five factors on PDC cutter performance on Alabama marble. The factors include: depth of cut (DOC), rotary speed, back rake angle, side rake angle, and confining (wellbore) pressure. The performance is quantified by two parameters: mechanical specific energy (MSE) and friction angle. Fractional factorial design of experiments methodology was used to design the experiments, enabling detection of potential interactions between factors. Results show that, in the range tested, the only statistically significant factor affecting the MSE is DOC. In other words, DOC's influence is predominant and it can mask the effect of all the other factors. These results could have applications in real time pore pressure detection. Further, the results show that back rake angle is the most statistically significant factor in friction angle. Side rake angle and depth of cut also affect the friction angle, but in a relatively unimportant manner. The MSE–DOC behavior is explained and modeled by cutter edge–groove friction and the circular cutter shape. It is speculated that high cutter edge friction overwhelms the actual cutting process. A comparison of five currently present models in the literature with these results is presented and the conclusion is that the future PDC cutter models should digress from the traditional shear failure plane models.

scholarly journals A new approach to evaluate rock drillability of polycrystalline diamond compact bits using scratch test data

2020 ◽  
Vol 38 (4) ◽  
pp. 884-904 ◽  
Author(s):  
Yannong Han ◽  
Xiaorong Li ◽  
Yongcun Feng
Keyword(s):  
Specific Energy ◽  
Polycrystalline Diamond ◽  
New Method ◽  
New Model ◽  
The Core ◽  
Mechanical Specific Energy ◽  
Rock Drillability ◽  
Micro Drilling ◽  
Scratch Tests ◽  
Polycrystalline Diamond Compact

Rock drillability is a comprehensive index that indicates the ease of drilling a hole in the rock mass, which is a main basis for the design of drilling bits, the optimization of drilling operational parameters, and the prediction of rate of penetration. This paper established a conversion relationship between mechanical specific energy measured from micro-drilling tests and mechanical specific energy measured from scratch tests, based on the consistency of rock breaking mechanism between these two types of tests. By incorporating the methodology of calculating rock drillability grade of polycrystalline diamond compact bits, a new mathematical model for predicting rock drillability of polycrystalline diamond compact bits is developed. Subsequently, a new method for acquiring continuous rock drillability profile by scratching the core surface is developed. A wide range of rocks with different hardness were tested by the proposed scratch method. The results show that the new model has high consistency with the results of laboratory micro-drilling tests. For example, the average errors of sandstone, shale, and carbonate test results are only 7.41%, 8.18%, and 4%, respectively. The new method can fully characterize the effect of mineral composition, cementation strength, and microstructure of rock on drillability. Besides, the new model has high utilization efficiency of expensive core samples because the core usually remains nondestructive after scratch tests.

The Effect on Cutting Tool Forces of Pre-Weakening a Rock Surface by Waterjet Kerfing

1989 ◽  
Vol 111 (1) ◽  
pp. 1-6
Author(s):  
J. E. Geier ◽  
M. Hood
Keyword(s):  
Unit Volume ◽  
Cutting Tool ◽  
Normal Force ◽  
Mechanical Energy ◽  
Polycrystalline Diamond ◽  
Empirical Models ◽  
Depth Of Cut ◽  
Rock Surface ◽  
Mechanical Specific Energy ◽  
Polycrystalline Diamond Compact

Empirical models are developed to describe the influence on the cutting process of preweakening a rock, by cutting a series of parallel kerfs in the surface with high pressure waterjets, prior to excavating the rock with a polycrystalline diamond compact (PDC) drag bit. These models show that both the bit cutting force and the bit normal force are reduced substantially (by as much as a factor of four) when the spacing and the depth of the kerfs is appropriate to the depth of cut taken by the bit. The mechanical specific energy, or the mechanical energy applied to the bit to excavate a unit volume of rock, is also reduced dramatically when the rock is prekerfed.

scholarly journals Experimental Investigation of Force Response, Efficiency, and Wear Behaviors of Polycrystalline Diamond Rock Cutters

2019 ◽  
Vol 9 (15) ◽  
pp. 3059 ◽  
Author(s):  
Huaping Xiao ◽  
Shuhai Liu ◽  
Kaiwen Tan
Keyword(s):  
Cutting Force ◽  
Oil And Gas ◽  
Drilling Fluid ◽  
Polycrystalline Diamond ◽  
Friction Angle ◽  
Rake Angle ◽  
Oil And Gas Exploration ◽  
Drilling Technology ◽  
Air Drilling ◽  
Dry Conditions

Polycrystalline diamond compact (PDC) cutters are the most extensively used tool for rock drilling in superdeep oil and gas exploration, in which the air drilling technology without drilling fluid is highly promoted. This study examined the performance of PDC cutters in air drilling, including their friction angle, cutting force, specific energy, and wear behaviors, using a home-made testing apparatus and a commercial tribometer. It also investigated the dependence of cutting force on cutting depth and back rake angle. Results obtained in both dry conditions and in drilling fluid media were compared, and a tentative explanation to the observed differences was brought about by these two environments.

Fragmentation Characteristics of Rocks Under Indentation by a Single Polycrystalline Diamond Compact Cutter

2021 ◽  
Vol 143 (10) ◽  
Author(s):  
Zhaosheng Ji ◽  
Huaizhong Shi ◽  
Xianwei Dai ◽  
Hengyu Song ◽  
Gensheng Li ◽  
...  
Keyword(s):  
Contact Force ◽  
Brittle Failure ◽  
Failure Modes ◽  
Polycrystalline Diamond ◽  
Rake Angle ◽  
Von Mises Stress ◽  
Rock Interaction ◽  
Initiation Point ◽  
Pdc Bit ◽  
Polycrystalline Diamond Compact

Abstract Polycrystalline diamond compact (PDC) bit accounts for the most drilling footage in the development of deep and geothermal resources. The goal of this paper is to investigate the PDC cutter-rock interaction and reveal the rock fragmentation mechanism. A series of loading and unloading tests are conducted to obtain the curves of contact force versus penetration displacement. A single practical PDC cutter is fixed on the designed clamping devices that are mounted on the servo experiment system TAW-1000 in the tests. The craters morphology and quantified data were obtained by scanning the fragmented rock specimen using a three-dimensional morphology scanner. Finally, a numerical model is established to get the stress and deformation fields of the rock under a single PDC cutter. The results show that there are two kinds of failure modes, i.e., brittle failure and plastic failure, in the loading process. Marble is more prone to brittle fracture and has the lowest specific energy, followed by shale and granite. The brittle failure in marble mainly occurs behind the cutter while that happens ahead of the cutter for shale. Curves of contact force versus penetration displacement illustrate that a cutter with a back rake angle of 40 deg has a better penetration result than that with a back rake angle of 30 deg. Enhancing loading speed has a positive effect on brittle fragmentation. The distribution of von Mises stress indicates the initiation point and direction, which has a good agreement with the experiment. The research is of great significance for optimizing the PDC bit design and increasing the rate of penetration.

scholarly journals Design and test of a self-adaptive bionic polycrystalline diamond compact bit inspired by cat claw

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401881024
Author(s):  
Qiongqiong Tang ◽  
Wei Guo ◽  
Ke Gao ◽  
Rongfeng Gao ◽  
Yan Zhao ◽  
...  
Keyword(s):  
Service Life ◽  
Soft Rock ◽  
Polycrystalline Diamond ◽  
Rake Angle ◽  
The Self ◽  
Test Results ◽  
Short Service Life ◽  
Polycrystalline Diamond Compact ◽  
Rock Strata ◽  
Self Adaptive

Cats protract claws while hunting or pawing on the ground and retract to muscles when relaxing. Inspired by this behavior, and in order to solve the problem of short service life and low comprehensive drilling efficiency of polycrystalline diamond compact bits which results from its poor adaptability to soft-hard interbedded strata, a self-adaptive bionic polycrystalline diamond compact bit was designed, which can use the elastic element to adjust its back-rake angle according to the formation hardness to improve the adaptability of polycrystalline diamond compact bits. Theoretical analysis and drilling test results show that the self-adaptive bionic polycrystalline diamond compact bit has a strong adaptability to soft-hard interbedded rock strata. When drilling in soft rock, the back-rake angle is small and the rate of penetration is high; when drilling in hard rock, the angle becomes larger to reduce the abnormal damage of cutters. Thus, it can improve the integrated drilling efficiency and service life of polycrystalline diamond compact bits. In the whole drilling test, the average penetration rate of the self-adaptive bionic polycrystalline diamond compact bit increases by 10%–13% over conventional polycrystalline diamond compact bits with the same dimension and material.

Development of New PDC Bits for Drilling of Geothermal Wells—Part 1: Laboratory Testing

1992 ◽  
Vol 114 (4) ◽  
pp. 323-331 ◽  
Author(s):  
H. Karasawa ◽  
S. Misawa
Keyword(s):  
Hard Rock ◽  
Rock Type ◽  
Penetration Rate ◽  
Polycrystalline Diamond ◽  
Rock Cutting ◽  
Rake Angle ◽  
Well Drilling ◽  
Pdc Bit ◽  
Geothermal Wells ◽  
Polycrystalline Diamond Compact

Rock cutting, drilling and durability tests were conducted in order to obtain data to design polycrystalline diamond compact (PDC) bits for geothermal well drilling. Both conventional and new PDC bits with different rake angles were tested. The rock cutting tests revealed that cutting forces were minimized at −10 deg rake angle independent of rock type. In drilling and durability tests, a bit with backrake and siderake angles of −10 or −15 deg showed better performance concerning the penetration rate and the cutter strength. The new PDC bit exhibited better performance as compared to the conventional one, especially in hard rock drilling. Furthermore, a new PDC core bit (98.4 mm o. d., 66 mm i. d.) with eight cutters could be successfully applied to granite drilling equally as well as a bit with twelve cutters.

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.

Design front rake angle of PDC bit based on SolidWorks simulation method

2016 ◽  
Vol 1 (3) ◽  
pp. 627 ◽  
Author(s):  
Xiaoming HAN ◽  
Chenxu LUO ◽  
Xingyu HAN
Keyword(s):  
Hard Rock ◽  
Simulation Analysis ◽  
Soft Rock ◽  
Polycrystalline Diamond ◽  
Simulation Method ◽  
Rake Angle ◽  
Element Simulation ◽  
Pdc Bit ◽  
Coal Rock ◽  
Polycrystalline Diamond Compact

<span lang="EN-US">In order to solve the bit front rake angle parameter selection problem of under different coal rock, it is proposed in polycrystalline diamond compact no core bit as the research object, and established a bit compact two-dimensional stress model of cutting teeth. The result shows that the front rake angle is the factor of cutting force and the drilling efficiency. Application of SolidWorks simulation carries out the finite element simulation analysis respectively to different front rake angle of bit model under the condition of soft rock and hard rock. Form the simulation it concludes that under the condition of soft rock and hard rock, the optimal front rake angle is 10° and 15° respectively. It is obtained that the strength of the bit is largest and the life is longest on the best front rake angle of bit.</span>

Modeling of Cutting Rock: From PDC Cutter to PDC Bit—Modeling of PDC Cutter

SPE Journal ◽  
2021 ◽  
pp. 1-21
Author(s):  
Pengju Chen ◽  
Stefan Miska ◽  
Mengjiao Yu ◽  
Evren Ozbayoglu
Keyword(s):  
Stress State ◽  
Cutting Forces ◽  
Polycrystalline Diamond ◽  
Rake Angle ◽  
Cutting Process ◽  
Model Studies ◽  
3D Space ◽  
Pdc Bit ◽  
Polycrystalline Diamond Compact ◽  
Good Agreement

Summary The main purpose of this paper is to present our polycrystalline diamond compact (PDC) cutter model and its verification. The PDC cutter model we developed is focused on a PDC cutter cutting a rock in 3D space. The model studies the forces between a cutter and a rock and applies the theory of poroelasticity to calculate the stress state of the rock during the cutting process. Once the stress state of the rock is obtained, the model can then predict rock failure by the modified Lade criterion (Ewy 1999). This work also developed a trial-and-error procedure to predict cutting forces, and the stress state of a rock before cutting process is also considered. A complete verification of the cutter model is conducted. The model results (i.e., predicted cutting forces) are compared with measured cutting forces from cutter tests in multiple published articles. The major influencing factors on cutting forces—backrake angle, side-rake angle, depths of cut, worn depth (or wear flat area), and hydrostatic pressure—are all studied and verified. A good agreement between the model results and cutter test data is found, and the overall mean relative error is approximately 15%. The influence of inhomogeneous precut stress state of a rock is also studied. Overall, the cutter model in this paper is complete and accurate. It is ready to be integrated into a PDC bit model.

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