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

Qiongqiong Tang,Ke Gao,Yang Sun,Yan Zhao,Yu Zhou,Wei Guo,Rongfeng Gao

doi:10.1177/1687814018810249

Abstract

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.

Highlights

Polycrystalline diamond compact (PDC) bits are widely used in the fields of oil drilling and geological exploration because of their high rock-cutting efficiency, long service life, and less drilling faults.[1,2] Especially in softand medium-hard rock formation, the drilling efficiency and service life are much higher than cone bits and cemented carbide bits.[3]
Results and discussion about the back-rake angle of self-adaptive bionic bit Figure 13 shows the relationship between the back-rake angle and the hardness when self-adaptive bionic PDC bit drilled in different kinds of rocks
The selfadaption and drilling performance have been evaluated through the mechanical analysis, the back-rake angle testing, and the rate of penetration (ROP) testing

Summary

Introduction

Polycrystalline diamond compact (PDC) bits are widely used in the fields of oil drilling and geological exploration because of their high rock-cutting efficiency, long service life, and less drilling faults.[1,2] Especially in softand medium-hard rock formation, the drilling efficiency and service life are much higher than cone bits and cemented carbide bits.[3]. In order to increase the ROP in the glutenite formation of the Pearl River Mouth Basin (PRMB) oil field, HY Zhu et al.[10] designed a specialized PDC bit with six blades of a new tiger tooth and an anticollision tooth to increase its shock and wear resistance. For the complex formation in Western South China Sea oilfields, HY Zhu et al.[11] established the prediction models of rock mechanics parameters based on the rock properties (drillability, plasticity, abrasiveness, and so on) and optimized the PDC bits for the different prediction models. The drilling efficiency of these bits for certain stratum has improved, when drilling in the soft-hard interbedded strata, their integrated drilling effect is not often ideal. It is necessary for us to design a PDC bit which can adapt to strata with different characteristics

Results

Discussion

Conclusion