Gas-hydrate formation, agglomeration and inhibition in oil-based drilling fluids for deep-water drilling

One of the main challenges in deep-water drilling is gas-hydrate plugs, which make the drilling unsafe. Some oil-based drilling fluids (OBDF) that would be used for deep-water drilling in the South China Sea were tested to investigate the characteristics of gas-hydrate formation, agglomeration and inhibition by an experimental system under the temperature of 4 ℃ and pressure of 20 MPa, which would be similar to the case of 2000 m water depth. The results validate the hydrate shell formation model and show that the water cut can greatly influence hydrate formation and agglomeration behaviors in the OBDF. The oleophobic effect enhanced by hydrate shell formation which weakens or destroys the interfacial films effect and the hydrophilic effect are the dominant agglomeration mechanism of hydrate particles. The formation of gas hydrates in OBDF is easier and quicker than in water-based drilling fluids in deep-water conditions of low temperature and high pressure because the former is a W/O dispersive emulsion which means much more gas-water interfaces and nucleation sites than the later. Higher ethylene glycol concentrations can inhibit the formation of gas hydrates and to some extent also act as an anti-agglomerant to inhibit hydrates agglomeration in the OBDF.     

Thermal processes taking place in the bone during CO2 laser irradiation

The present study examines the drilling and heating of a bone due to pulsed CO₂ laser irradiation. To obtain temperature profiles inside and at the surface of the bone, electron-kinetic and Fourier theories are used. The study is extended to include an experimental investigation into the measurement of the penetration speed. This is achieved using a fibre-optic system. In order to reduce the degree of burning around the hole side, helium was used as the assisting gas during drilling. It is found that the penetration speeds predicted from the theory are in good agreement with the experimentally obtained values.     

钻进速度对钻杆扭矩影响的理论分析与试验研究

利用钻杆扭矩法预测冲击地压等煤矿动力灾害时,钻进速度是影响钻杆扭矩的一个重要因素。研究钻进速度对钻杆扭矩的影响可以减少预测指标的误差,提高预测准确性。利用自主研发的钻杆扭矩测试装置,对预制煤体相似材料试件进行了不同钻进速度下的钻孔试验,研究了不同钻进速度对钻杆扭矩变化的影响规律。试验结果表明:钻进速度对钻杆扭矩影响很大。同种煤岩体材料,相同压力条件下,钻进速度越快,钻杆扭矩越大,反之,钻杆扭矩越小。上述研究成果可用于减少预测指标误差。     

页岩气高效开采的力学问题与挑战

页岩气是指赋存于富含有机质泥页岩中以吸附和游离状态为主要存在方式的天然气,中国资源量丰富,地域分布广泛.页岩气开采能缓解我国常规油气产量不足、煤化石燃料引起环境污染等问题,已成为中国绿色能源开发的重要领域.尽管北美页岩气"革命"取得了成功,目前也仅有预期产量5%～15%的采收率.与北美地区相比,中国页岩气埋藏深,赋存条件差,自然丰度低,因此,高效开采面临更多的困难和挑战.近年来,围绕国家重大能源战略需求,瞄准技术发展前沿,学术界和工业界联合对页岩气高效开采的关键科学和技术问题展开研究.本文结合近三年四川、重庆地区的页岩气试验区块遇到的新问题,针对中国未来3 500 m以下深部开采的新挑战,如地质沉积、裂缝发育构造不同、上覆压力增加、水平应力场变化等新问题,介绍和总结了目前中国页岩气高效开采面临的力学科学问题,主要包括多重耦合下的安全优质钻完井力学理论和方法、水力压裂体积改造和多尺度缝网形成机制、多尺度渗流力学特性与解吸附机理等."深部页岩气高效开采"的研究面向国家重大能源需求,科学意义重大,工程背景明确,需要工程力学、石油工程、地球物理、化学工程和环境工程等多学科专家合作,开展理论研究、物理模拟、数值模拟及现场试验等综合应用基础研究,取得高效开采页岩油气理论与技术的突破.学科交叉是研究页岩气高效开采问题、突破技术瓶颈的桥梁,只有力学与石油工程、地球科学等学科实现深度交叉融合,才能更加有效地推动页岩油气等非常规油气资源的开发.     

高取代度阳离子淀粉的合成及其降滤失性能

高取代度阳离子淀粉的合成及其降滤失性能;环氧丙基三甲基氯化铵;阳离子淀粉;半干法;钻井液;降滤失剂     

地下定向钻进姿态测量系统的设计

针对地下钻进的特殊要求,描述了一种定向钻进姿态测量系统,对系统具体的结构以及姿态解算方法同时进行了详细说明。该系统采用新型微硅加速度计和磁阻式磁强计作为姿态敏感器件,实时获取定向钻进中钻具的方位角、倾角和面向角信息。此系统具有体积小、成本低、可靠性高等一系列优点,非常适合地下钻进测量。     

RESEARCH OF REGULARITY OF THROWING MOVEMENT FOR SOLID PARTICLE ON THE SHAKER''''S SCREEN

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Full-field calculation of hole drilling residual stresses from electronic speckle pattern interferometry data

A mathematical method is proposed for calculating residual stresses from hole drilling electronic speckle pattern interferometry (ESPI) data, independent of rigid-body motions. Even though the signal-to-noise ratio of typical ESPI data is modest, the method achieves good computational stability by averaging a large amount of data. It does this without excessive numerical effort by exploiting known trigonometric relationships among the data. The resulting stress calculations are very rapid, and are well suited for future application to non-uniform stress measurements.     

Novel Amphiphilic Comb-Like Polymers: Synthesis,Characterization, and Their Properties as Viscosifying and Filtration Additives for Drilling Fluids

Novel amphiphilic comb-like polymers (CPASA), used as viscosifying and filtration loss additives for low-solid water-based drilling fluids under high temperature and salinity conditions, were prepared from acrylamide, sodium 4-styrenesulfonate, and allyl polyethylene glycol ether with toluylene-end groups via inverse microemulsion polymerization. The chemical structure was characterized by Fourier transform infrared spectroscopy (FTIR) and hydrogen nuclear magnetic resonance (¹H-NMR). The thermal stability, aqueous solution properties, and drilling fluid properties were evaluated. Results showed that the comb-like polymers exhibited dramatic enhancement in their thermal- and salt-resistant properties because of the steric hindrance and intermolecular associations of the side-chains. The rheological properties, filtration properties, and negative Zeta potentials of both fresh-water drilling fluid and saturated salt-water drilling fluid were greatly improved by the addition of CPASA before and after thermal aging tests, which were ascribed to the steric hindrance of its comb-like conformation, the strong electrical double layer force of clay particles, and the stable mud network formed by CPASA and clay particles in drilling fluid.     

Measurement of residual stresses in polymeric parts by indentation method

An indentation method was studied as a means of measuring the residual stress in an injection molded polymeric specimen because destructive methods restrict the reuse of measured parts and it is not possible to apply them to small and complicated parts. The load-displacement curve was measured for indentation at stressed and non-stressed positions. Residual stress distribution of the injection molded part was calculated by comparing the load-displacement curve results with respect to the indentation depth. The residual stresses measured by the indentation method were reliable because they were in good agreement with numerical results and those measured by the hole drilling method. The indentation method can be utilized to measure the residual stresses in polymeric parts for practical applications, particularly for small or complicated parts.