The Experts below are selected from a list of 897 Experts worldwide ranked by ideXlab platform
Yong Liu - One of the best experts on this subject based on the ideXlab platform.
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Analysis of the stress wave effect during coal breakage by a high-pressure abrasive air jet:
Advances in Mechanical Engineering, 2018Co-Authors: Yong Liu, Zhang Tao, Xiaotian LiuAbstract:In view of the defects of Borehole Collapse, inhibition of gas desorption and migration of gas existing in hydraulic fracturing and other hydraulic permeability–increasing measures for soft coal se...
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Optimal Nozzle Structure for an Abrasive Gas Jet for Rock Breakage
Hindawi Limited, 2018Co-Authors: Yong Liu, Tao Zhang, Juan Zhang, Huidong ZhangAbstract:Abrasive gas jet technologies are efficient and beneficial and are widely used to drill metal and glass substrates. When the inlet pressure is increased, gas jets could be powerful enough to break rock. They have potential uses in coal-bed methane exploration and drilling because of their one-of-a-kind nonliquid jet drilling, which avoids water invasion and Borehole Collapse. Improving the efficiency of rock breakage using abrasive gas jets is an essential precondition for future coal-bed methane exploration. The nozzle structure is vital to the flow field and erosion rate. Furthermore, optimizing the nozzle structure for improving the efficiency of rock breakage is essential. By combining aerodynamics and by fixing the condition of the nozzle in the drill bit, we design four types of preliminary nozzles. The erosion rates of the four nozzles are calculated by numerical simulation, enabling us to conclude that a nozzle at Mach 3 can induce maximum erosion when the pressure is 25 MPa. Higher pressures cannot improve erosion rates because the shield effect decreases the impact energy. Smaller pressures cannot accelerate erosion rates because of short expansion waves and low velocities of the gas jets. An optimal nozzle structure is promoted with extended expansion waves and less obvious shield effects. To further optimize the nozzle structure, erosion rates at various conditions are calculated using the single-variable method. The optimal nozzle structure is achieved by comparing the erosion rates of different nozzle structures. The experimental results on rock erosion are in good agreement with the numerical simulations. The optimal nozzle thus creates maximum erosion volume and depth
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Application of drilling in roof or floor with high pulse pressure water jet to improve gas drainage
Meitan Xuebao/Journal of the China Coal Society, 2010Co-Authors: Yong Liu, X.h. Li, Yiyu Lu, Binwei XiaAbstract:Analyzed the mechanism of Borehole Collapse in soft seam and completed in hard seam. On that basis, provided a new way of drilling Borehole, which was drilling Borehole in hard seam, floor or roof and then slotting the coal with high pulsed pressure water jet. Based on the dynamic of the high pressure water jet, the pressure and flow rate of the water jet were calculated. Then the gas drainage system of high pressure pulsed water jet were developed and applied successfully in a typical mine with rich gas and low permeability in Sichuan Province. According to the results, the Borehole length drilled by new technology is 2.7times of the original. Besides, the gas flow of per drilling slotted by high pressure water jet is 0.19~0.26m3/min on average is 5.2times of the original.
Deng Jingen - One of the best experts on this subject based on the ideXlab platform.
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Study on Wellbore Stability and Instability Mechanism in PiedmontStructures
The Open Petroleum Engineering Journal, 2015Co-Authors: Tan Qiang, Deng Jingen, Kai Zhao, Chen JianguoAbstract:Piedmont tectonic belts are rich of oil and gas resources, however the intense tectonic stress and broken forma- tion may cause great drilling problems in piedmont structures such as Borehole Collapse, lost circulation and gas cutting. Through analysis of in situ stress properties, bedding structure and mechanical characteristics, wellbore instability mecha- nism was expounded from rock mechanics, chemistry of drilling fluid and drilling technology. The high tectonic stress, formation strength decreasing and fluid pressure rising after mud filtrate seepage are main reasons for Borehole Collapse. The methods of calculating Collapse and fracture pressure and determining drilling safety density window were put for- ward based on mechanical analysis. In order to reduce drilling problems in piedmont structures, some countermeasures should be taken from optimizing well track and casing program, using proper mud density, improving inhibitive and sealing ability of drilling fluid. Good sealing ability can reduce seepage and cut off pressure transmission, enhancing the effective support force. This is the key technology of maintaining wellbore stability in hard brittle shale in piedmont structures.
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The Permeability Property and Borehole Stability in Bedding Shale
Petroleum Science and Technology, 2013Co-Authors: Qiang Tan, Deng Jingen, Yongcun FengAbstract:Wellbore Collapse is one of the often encountered problems when drilling through shale formations. The instability mechanism and effect factors should be made sure to adopt suitable countermeasures. The bedding shale's permeability was measured by experiment, and with this foundation, the effects of drilling fluid seepage on formation strength and wellbore stability were discussed. Results showed that laminar shale's permeability is anisotropic and random. The permeability is extremely low in the direction perpendicular to the bedding plane, and it is very high parallel to the bedding plane when there are interlayer microcracks. The drilling fluid permeating along the bedding plane leads to great decrease on cohesion and internal friction angle, and then decreases the shale formation's strength, finally leading to Borehole shrinkage, pipe sticking, and Borehole Collapse. Increasing mud weight only is good for Borehole stability in short term. However, it intensifies seepage finally and can't control boreh...
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Calculating Method of Wellbore Collapse Pressure Drilling in Fractured Shale Formation
International Journal of Digital Content Technology and Its Applications, 2013Co-Authors: Deng Jingen, Song Lihui, Yu Baohua, Yuan Liang, Lu NanaAbstract:In order to reduce the oil and gas drilling risk and cost, the calculating method of Collapse pressure was established to prevent Borehole Collapse in fractured shale formation. The method was coupled with Borehole concentrated stress, induced stress by crack opened and pore pressure change. The influence law of Borehole trajectory and crack occurrence was researched. The results show that, Collapse pressure increases substantially in small dip fractured shale formation when the well deviation angle exceeds the critical value, and the increase speed is fastest in the direction of maximum horizontal principle stress; Collapse pressure is lower when crack is nearly vertical and the tendency parallel to wellbore azimuth for the horizontal well, but when crack dip exceeds 30° and the tendency is not parallel to wellbore azimuth, it is more dangerous for drilling due to the higher Collapse pressure. The research results can be used to solve wellbore instability problems and improve drilling efficiency in the similar regions.
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Wellbore Instability and Countermeasures in Offshore Bedding Shale Formations
Petroleum Science and Technology, 2010Co-Authors: Tan Qiang, Deng Jingen, Yu BaohuaAbstract:Abstract The properties of bedding shales are different from that of normal formations. Strength anisotropy is their outstanding feature. Experimental study and theoretical analysis show that this kind of anisotropy of bedding shales is the main reason of wellbore instability. W-2nd section shales in WZ12-1N oilfield are in typical bedding formation, and there were some problems such as severe Borehole Collapse and pipe sticking in drilling. Bedding shale formation was assumed to be a transversely isotropic material, and a Collapse pressure calculating method was established. The calculation result of directional drilling Collapse pressure in W-2nd bedding shales shows that if hole deviation exceeds a certain critical value, Collapse pressure will increase sharply. This result was used in mud density design and well trajectory optimization, which solved the wellbore instability problems of the W-2nd formation. This research method has reference value to solve problems of wellbore instability and improve d...
Duane R. Mikulencak - One of the best experts on this subject based on the ideXlab platform.
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From Wellbore Instability and Grain Mixing to Injectivity Reduction
Rock Mechanics and Rock Engineering, 2019Co-Authors: Alvin W. Chan, Sharad Yadav, Duane R. MikulencakAbstract:Wellbore instability has been registered and expected as one of the risks for successful delivery of horizontal injectors with open-hole stand-alone screens in depleted reservoirs. Special drill-in fluids and breaker fluids were designed to ensure stability of these wells prior to screen installations. Borehole Collapse was expected in most cases after the wellbore pressure dropped to hydrostatic at the end of the drilling process. Unlike open-hole producers, the loose particles (or grains) trapped in the annulus of the open-hole injectors will likely undergo constant mixing and resorting during each injection and shut-in cycles. In this study, we examined the impacts of grain mixing on the reduction of porosity and permeability in the annulus using a simple binary mixing model. Laboratory experiments based on this hypothesis have also been conducted. Our preliminary results suggest that if the fines are 10 to 20 times smaller than the larger particles, the presence of a few percent in volume fraction of fine particles can reduce permeability by an order of magnitude. The predicted reductions are consistent with the observed equivalent skin increases at some of our injectors during the first few years of operations. After multiple stimulations to remove fines and residual drilling additives, we successfully re-established injectivities to the initial states.
S. Rahman - One of the best experts on this subject based on the ideXlab platform.
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Risk-controlled wellbore stability analysis in anisotropic formations
Journal of Petroleum Science and Engineering, 2015Co-Authors: Majed F. Kanfar, Zhixi Chen, S. RahmanAbstract:Abstract The paper presents a semi-analytical solution for the stability of inclined Boreholes drilled in isotropic and anisotropic formations. Conventional analytical or semi-analytical models are designed to yield no Borehole Collapse failure along the Borehole wall. However, in deep wells, where there are high hoop stresses acting on the Borehole wall, it is difficult to apply the safe mud weight produced by these ubiquitous models. The proposed solution in this work imposes a constraint on how much failure will occur along the Borehole wall. This risk-controlled stability analysis will produce a safe mud window that can be realistically achieved during drilling operations. Analytical solutions for stress distribution for isotropic and anisotropic rocks are presented. In addition, a solution for the upper limit for the mud window to prevent tensile failure is developed. The initial poroelastic or “undrained” drilling effect on pore pressure is also incorporated in the discussed models.
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Borehole Collapse analysis incorporating time-dependent pore pressure due to mud penetration in shales
Journal of Petroleum Science and Engineering, 2000Co-Authors: M.k. Rahman, D. Naseby, S. RahmanAbstract:This paper presents a model to predict time-dependent instability of arbitrarily oriented wellbores. The underlying factor to make the Borehole Collapse time-dependent is the increase of pore pressure around the wellbore due to mud penetration over time. The time-dependent pore pressure around the wellbore is estimated by analyzing two-phase fluid flow in porous media. The petrophysical parameters required for two-phase flow analysis, such as capillary pressure and absolute and relative permeabilities are characterized from experimental data. The model for time-dependent Borehole Collapse analysis is then developed by incorporating the transient pore pressure in the widely used wellbore failure analysis model. Potential wellbore failure modes are mathematically defined and guidance is incorporated to identify the upper and the lower bounds of the safe mud window at a particular time. The developed model is applied to wells in shale under different stress regimes. Results demonstrate that an initial safe mud window becomes narrower as the time progresses. Consequently, a mud weight, which was initially safe, may become unsafe and results in Borehole Collapse after a certain period of time. Such a failure is further influenced by the orientation of the wellbore and different stress regimes.
Tan Qiang - One of the best experts on this subject based on the ideXlab platform.
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Study on Wellbore Stability and Instability Mechanism in PiedmontStructures
The Open Petroleum Engineering Journal, 2015Co-Authors: Tan Qiang, Deng Jingen, Kai Zhao, Chen JianguoAbstract:Piedmont tectonic belts are rich of oil and gas resources, however the intense tectonic stress and broken forma- tion may cause great drilling problems in piedmont structures such as Borehole Collapse, lost circulation and gas cutting. Through analysis of in situ stress properties, bedding structure and mechanical characteristics, wellbore instability mecha- nism was expounded from rock mechanics, chemistry of drilling fluid and drilling technology. The high tectonic stress, formation strength decreasing and fluid pressure rising after mud filtrate seepage are main reasons for Borehole Collapse. The methods of calculating Collapse and fracture pressure and determining drilling safety density window were put for- ward based on mechanical analysis. In order to reduce drilling problems in piedmont structures, some countermeasures should be taken from optimizing well track and casing program, using proper mud density, improving inhibitive and sealing ability of drilling fluid. Good sealing ability can reduce seepage and cut off pressure transmission, enhancing the effective support force. This is the key technology of maintaining wellbore stability in hard brittle shale in piedmont structures.
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Wellbore Instability and Countermeasures in Offshore Bedding Shale Formations
Petroleum Science and Technology, 2010Co-Authors: Tan Qiang, Deng Jingen, Yu BaohuaAbstract:Abstract The properties of bedding shales are different from that of normal formations. Strength anisotropy is their outstanding feature. Experimental study and theoretical analysis show that this kind of anisotropy of bedding shales is the main reason of wellbore instability. W-2nd section shales in WZ12-1N oilfield are in typical bedding formation, and there were some problems such as severe Borehole Collapse and pipe sticking in drilling. Bedding shale formation was assumed to be a transversely isotropic material, and a Collapse pressure calculating method was established. The calculation result of directional drilling Collapse pressure in W-2nd bedding shales shows that if hole deviation exceeds a certain critical value, Collapse pressure will increase sharply. This result was used in mud density design and well trajectory optimization, which solved the wellbore instability problems of the W-2nd formation. This research method has reference value to solve problems of wellbore instability and improve d...