Numerical modelling of bottom-hole rock in underbalanced drilling using thermo-poroelastoplasticity model

Weiji Liu,Yun-Lai Zhou,Xiaohua Zhu,Xiannan Meng,Mei Liu,Magd Abdel Wahab 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.69 No.5

Stress analysis of bottom-hole rock has to be considered with much care to further understand rock fragmentation mechanism and high penetration rate. This original study establishes a fully coupled simulation model and explores the effects of overburden pressure, horizontal in-situ stresses, drilling mud pressure, pore pressure and temperature on the stress distribution in bottom-hole rock. The research finds that in air drilling, as the well depth increases, the more easily the bottom-hole rock is to be broken. Moreover, the mud pressure has a great effect on the bottom-hole rock. The bigger the mud pressure is, the more difficult to break the bottom-hole rock is. Furthermore, the maximum principal stress of the bottom-hole increases as the mud pressure, well depth and temperature difference increase. The bottom-hole rock can be divided into three main regions according to the stress state, namely a) three directions tensile area, b) two directions compression areas and c) three directions compression area, which are classified as a) easy, b) normal and c) hard, respectively, for the corresponding fragmentation degree of difficulty. The main contribution of this paper is that it presents for the first time a thorough study of the effect of related factors, including stress distribution and temperature, on the bottom-hole rock fracture rather than the well wall, using a thermo-poroelastoplasticity model.

A New Approach of Rock Cutting Efficiency Evaluation by using Plastic Energy Dissipation Ratio

Weiji Liu,Xiaohua Zhu 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.2

Polycrystalline Diamond Compact (PDC) bit is extensively used in oil & gas drilling, the rock cutting efficiency of PDC cutter directly determines the drilling efficiency and costs. Hence, it is crucial to evaluate the rock cutting efficiency of PDC cutters. The Mechanical Specific Energy (MSE) is used as an index for long periods of time to evaluate the rock cutting efficiency, however, the energy dissipation in rock breaking cannot be further calculated in details, leading to inaccuracy. To address this problem, the new concept of Plastic Energy Dissipation Ratio (PEDR) and its model are presented, a new approach for rock cutting efficiency evaluation by using PEDR is also put forward. Compared with MSE, the PEDR can determine the Optimum Depth of Cut (DOC) under various conditions. The theoretical analysis shows that the critical DOC, governing the transition of ductile to brittle failure mode, is the optimal cutting depth, having the smallest PEDR and highest rock cutting efficiency. The test and simulation of rock cutting are carried out to verify the PEDR model, and the PEDR under different DOC, cutting velocities and rake angles are depicted and discussed. The results can provide a theoretical basis for the design of PDC cutter and optimization of drilling parameters.

The ROP mechanism study in hard formation drilling using local impact method

Liu, Weiji,Zhu, Xiaohua,Zhou, Yunlai,Mei, Liu,Meng, Xiannan,Jiang, Cheng Techno-Press 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.1

The low rate of penetration and short lifetime of drilling bit served as the most common problems encountered in hard formation drilling, thus leading to severe restriction of drilling efficiency in oil and gas reservoir. This study developed a new local impact drilling method to enhance hard formation drilling efficiency. The limitation length formulas of radial/lateral cracks under static indentation and dynamic impact are derived based on the experimental research of Marshall D.B considering the mud column pressure and confining pressure. The local impact rock breaking simulation model is conducted to investigate its ROP raising effect. The results demonstrate that the length of radial/lateral cracks will increase as the decrease of mud pressure and confining pressure, and the local impact can result in a damage zone round the impact crater which helps the rock cutting, thus leading to the ROP increase. The numerical results also demonstrate the advantages of local impact method for raising ROP and the vibration reduction of bit in hard formation drilling. This study has shown that the local impact method can help raising the ROP and vibration reduction of bit, and it may be applied in drilling engineering.

Bonded-cluster simulation of tool-rock interaction using advanced discrete element method

Weiji Liu,Xiaohua Zhu,Yun-Lai Zhou,Tao Li,Xiangning Zhang 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.72 No.4

The understanding of tool-rock interaction mechanism is of high essence for improving the rock breaking efficiency and optimizing the drilling parameters in mechanical rock breaking. In this study, the tool-rock interaction models of indentation and cutting are carried out by employing the discrete element method (DEM) to examine the rock failure modes of various brittleness rocks and critical indentation and cutting depths of the ductile to brittle failure mode transition. The results show that the cluster size and inter-cluster to intra-cluster bond strength ratio are the key factors which influence the UCS magnitude and the UCS to BTS ratio. The UCS to BTS strength ratio can be increased to a more realistic value using clustered rock model so that the characteristics of real rocks can be better represented. The critical indentation and cutting depth decrease with the brittleness of rock increases and the decreasing rate reduces dramatically against the brittleness value. This effort may lead to a better understanding of rock breaking mechanisms in mechanical excavation, and may contribute to the improvement in the design of rock excavation machines and the related parameters determination.

Large-eddy simulation of low-swirl multi-nozzle combustion with co- and counter-swirling arrays

Weijie Liu,Bing Ge,Shusheng Zang,Huiru Wang 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.1

Large-eddy simulation (LES) of CH 4 -air low-swirl flame was carried out in a multi-nozzle combustor with two burner configurations by using a premixed flamelet model. The multi-nozzle burner includes a co-swirling array where all five nozzles act in the same direction and a counter-swirling array where the center nozzle is in the opposite swirling direction to the outer nozzles. LES results are in good agreement with OH-planar laser-induced florescence data in terms of OH concentrations and combustion progress variables. Numerical results show that the flow of each nozzle is constant before merging. The neighboring flows interact with each other and generate a highvelocity zone with intensive turbulence. The kinetic energy in the interacting region for the co-swirling array is larger than that for the counter-swirling array. After neighboring flow combining, the flow develops into a unified swirling motion similar to a single swirling flow for the co-swirling array, whereas the flow maintains the individual swirling structures for the counter-swirling arrangement. However, the swirling array exerts minimal effect on multi-nozzle combustion in terms of the temperature distributions and combustion progress of premixed low-swirl multi-nozzle flames.

Effects of temperature on the development and reproduction of sugarcane top borer Scirpophaga excerptalis (Lepidoptera: Pyralidae)

Weiji Liu,Huang Cheng-Hua,Pan Xue-Hong,Shang Xian-Kun,Nikpay Amin,Goebel François-Régis 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.3

To determine the effects of temperature on the development and reproduction of top borer Scirpophaga excerptalis Walker (Lepidoptera: Pyralidae), the durations of different developmental stages and reproductive capacity of S. excerptalis were measured at 20, 23, 26, 29 and 32℃. The results showed that the average durations of various developmental stages of S. excerptalis shortened with increasing temperatures from 20 to 32℃. The durations to complete one life cycle were 113.17 days at 20℃, and 39.50 days at 32℃. The developmental rate of each stage and generation was positively correlated with the temperature, which was consistent with the Logistic regression model. The temperature thresholds for egg, larval, pupal and preoviposition stages and the total cycle were 13.73, 14.73, 13.91, 13.66 and 14.10℃, respectively. The effective accumulative temperature was 112.62, 370.01, 188.17, 23.82 and 718.07 degree-days (DD), respectively. The adult longevity shortened with increasing temperatures, and the highest number of eggs laid per female was 204.74 eggs at 29℃. The survival rates of eggs, larvae and the whole generation were the highest at 26℃, which were 87.25%, 56.67% and 37.21%, respectively while the highest survival rate of the pupa was 76.69% at 29℃. There was no significant difference for the total cycle at 23-29℃. The results indicated that temperature was the key factor affecting the development and reproduction of S. excerptalis, and the optimum temperature for development and reproduction ranged from 23 to 29℃.

Synthesis and adsorption properties of chabazite-like zeolites

Weijie Liu,Lei Qian,Zong Chen,Liying Liu 대한환경공학회 2019 대한환경공학회 학술발표논문집 Vol.2019 No.-

Influence of dragon bamboo with different planting patterns on microbial community and physicochemical property of soil on sunny and shady slopes

Liu Weiyi,Wang Fang,Sun Yanmei,Yang Lei,Chen Huihai,Liu Weijie,Zhu Bin,Hui Chaomao,Wang Shiwei 한국미생물학회 2020 The journal of microbiology Vol.58 No.11

Dragon bamboo (Dendrocalamus giganteus) is a giant sympodial bamboo species widely distributed in Asia. However, it remains unclear how dragon bamboo and soil microbes interact to affect soil properties. In this study, we investigated the planting patterns (semi-natural and artificial) on different slopes (sunny and shady) to determine the effects on soil properties and microbial community. The results showed that the soil in which dragon bamboo was grown was acidic, with a pH value of ~5. Also, the soil organic matter content, nitrogen hydrolysate concentration, total nitrogen, available potassium, and total potassium of the dragon bamboo seminatural forest significantly improved, especially on the sunny slope. In contrast, the available phosphorus level was higher in the artificial bamboo forest, probably owing to the phosphate fertilizer application. The bacterial and fungal diversity and the bacterial abundance were all higher on the sunny slope of the semi-natural forest than those in the other samples. The microbial operational taxonomic units (OTUs) shared between the shady and sunny slopes accounted for 47.8–62.2%, but the core OTUs of all samples were only 24.4– 30.4% of each sample, suggesting that the slope type had a significant effect on the microbial community. Some acidophilic microbes, such as Acidobacteria groups, Streptomyces and Mortierella, became dominant in dragon bamboo forest soil. A PICRUSt analysis of the bacterial functional groups revealed that post-translational modification, cell division, and coenzyme transport and metabolism were abundant in the semi-natural forest. However, some microorganisms with strong stress resistance might be activated in the artificial forest. Taken together, these results illustrated the influence of dragon bamboo growth on soil physicochemical property and microbial community, which might help understand the growth status of dragon bamboo under different planting patterns.

The ROP mechanism study in hard formation drilling using local impact method

Weiji Liu,Xiaohua Zhu,Yun-Lai Zhou,Liu Mei,Xiannan Meng,Cheng Jiang 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.1

The low rate of penetration and short lifetime of drilling bit served as the most common problems encountered in hard formation drilling, thus leading to severe restriction of drilling efficiency in oil and gas reservoir. This study developed a new local impact drilling method to enhance hard formation drilling efficiency. The limitation length formulas of radial/lateral cracks under static indentation and dynamic impact are derived based on the experimental research of Marshall D.B considering the mud column pressure and confining pressure. The local impact rock breaking simulation model is conducted to investigate its ROP raising effect. The results demonstrate that the length of radial/lateral cracks will increase as the decrease of mud pressure and confining pressure, and the local impact can result in a damage zone round the impact crater which helps the rock cutting, thus leading to the ROP increase. The numerical results also demonstrate the advantages of local impact method for raising ROP and the vibration reduction of bit in hard formation drilling. This study has shown that the local impact method can help raising the ROP and vibration reduction of bit, and it may be applied in drilling engineering.

Ginsenoside Rb1 and compound K improve insulin signaling and inhibit ER stress-associated NLRP3 inflammasome activation in adipose tissue

Chen, Weijie,Wang, Junlian,Luo, Yong,Wang, Tao,Li, Xiaochun,Li, Aiyun,Li, Jia,Liu, Kang,Liu, Baolin The Korean Society of Ginseng 2016 Journal of Ginseng Research Vol.40 No.4

Background: This study was designed to investigate whether ginsenoside Rb1 (Rb1) and compound K (CK) ameliorated insulin resistance by suppressing endoplasmic reticulum (ER) stress-induced inflammation in adipose tissue. Methods: To induce ER stress, epididymal adipose tissue from mice or differentiated 3T3 adipocytes were exposed to high glucose. The effects of Rb1 and CK on reactive oxygen species production, ER stress, TXNIP/NLRP3 inflammasome activation, inflammation, insulin signaling activation, and glucose uptake were detected by western blot, emzyme-linked immunosorbent assay, or fluorometry. Results: Rb1 and CK suppressed ER stress by dephosphorylation of $IRE1{\alpha}$ and PERK, thereby reducing TXNIP-associated NLRP3 inflammasome activation in adipose tissue. As a result, Rb1 and CK inhibited IL-$1{\beta}$ maturation and downstream inflammatory factor IL-6 secretion. Inflammatory molecules induced insulin resistance by upregulating phosphorylation of insulin receptor substrate-1 at serine residues and impairing insulin PI3K/Akt signaling, leading to decreased glucose uptake by adipocytes. Rb1 and CK reversed these changes by inhibiting ER stress-induced inflammation and ameliorating insulin resistance, thereby improving the insulin IRS-1/PI3K/Akt-signaling pathway in adipose tissue. Conclusion: Rb1 and CK inhibited inflammation and improved insulin signaling in adipose tissue by suppressing ER stress-associated NLRP3 inflammation activation. These findings offered novel insight into the mechanism by which Rb1 and CK ameliorate insulin resistance in adipose tissue.