A two-dimensional horizontal wave propagation and mud mass transport model

The present study offers a two-dimensional horizontal wave propagation and morphodynamic model for muddy coasts. The model can be applied on a general three-dimensional bathymetry of a soft muddy coast to calculate wave damping, fluid mud mass transport and resulting bathymetry change under wave actions. The wave propagation model is based on time-dependent mild slope equations including the wave energy dissipation due to the wave-mud interaction of bottom mud layers as well as the combined effects of the wave refraction, diffraction and breaking. The constitutive equations of the visco-elastic–plastic model are adopted for the rheological behavior of fluid mud. The mass transport velocity within the fluid mud layer is calculated combining the Stokes’ drift, the mean Eulerian velocity and the gravity-driven mud flow. The results of the numerical model are compared against a series of conducted wave basin experiments, wave flume experiments and field observations. Comparisons between the computed results with both the field and laboratory data reveal the capability of the proposed model to predict the wave transformation and mud mass transport.     

Comparison of benthic foraminifera and macrofaunal indicators of the impact of oil-based drill mud disposal

We compare foraminifera and macrofauna as bio-indicators of oil-based drill mud disposal site off Congo. The most polluted sites are characterized by poor faunas, dominated by some very tolerant taxa. Slightly further from the disposal site, there is an area with strongly increased densities, heavily dominated by opportunistic taxa. Still further, macrofauna appears to be similar to that at the reference area, but the foraminiferal meiofauna still suggests a slight environmental perturbation. The foraminiferal FIEI index, based on the species distribution in the study area, appears to be more discriminative than the macrofaunal ITI index, based on a priori definitions of the trophic guilds of the various taxa. Our comparative approach allows us to point out the benefits of (1) the use of macrofauna and foraminifera together and (2) the definition of the species groups used in biotic indices on the basis of observations made directly in the study area.     

A Real-time Lithological Identification Method based on SMOTE-Tomek and ICSA Optimization

In petroleum engineering, real-time lithology identification is very important for reservoir evaluation, drilling decisions and petroleum geological exploration. A lithology identification method while drilling based on machine learning and mud logging data is studied in this paper. This method can effectively utilize downhole parameters collected in real-time during drilling, to identify lithology in real-time and provide a reference for optimization of drilling parameters. Given the imbalance of lithology samples, the synthetic minority over-sampling technique (SMOTE) and Tomek link were used to balance the sample number of five lithologies. Meanwhile, this paper introduces Tent map, random opposition-based learning and dynamic perceived probability to the original crow search algorithm (CSA), and establishes an improved crow search algorithm (ICSA). In this paper, ICSA is used to optimize the hyperparameter combination of random forest (RF), extremely random trees (ET), extreme gradient boosting (XGB), and light gradient boosting machine (LGBM) models. In addition, this study combines the recognition advantages of the four models. The accuracy of lithology identification by the weighted average probability model reaches 0.877. The study of this paper realizes high-precision real-time lithology identification method, which can provide lithology reference for the drilling process.     

JSN-2B型泥浆净化机振筛系统的优化设计

JSN2B型泥浆净化机是地勘单位普遍使用的泥浆处理设备,在实际使用过程中,由于振筛系统采用的是电机皮带传动带动偏心块产生振动的方式,维修设备和更换筛网不方便,影响净化机的正常使用。经研究分析,采用振动电机及复合筛网对其进行改造,改造后经过1年的实际应用,使用效果良好,维修保养方便,效益显著提升。     

KP泥浆在八面石矿区的实际应用与改进

八面石矿区的地层比较复杂,在钻孔施工中,易发生坍塌、掉块、缩径等现象,我们通过对KP泥浆的不断改进,在保证钻孔质量的前提下,有效地控制了孔内事故,提高钻进效率、降低钻进成本。     

广邻路华蓥山特长隧道岩溶地质问题与对策

公路、铁路等线路穿越岩溶地区时,合适的选线方法可降低工程造价、减少工程病害及环境影响,从而科学解决穿越与避让问题。拟建广安至邻水公路为双向四车道一级公路标准,初步设计阶段在工程可行性研究基础上采用低线A线和高线K线方案进行研究。华蓥山特长隧道穿越岩溶地区,为本项目的控制性工程。以华蓥山特长隧道为研究对象,在充分收集既有G42沪蓉高速华蓥山隧道相关资料的基础上,通过分析岩溶区岩溶发育规律、水文地质特点和岩溶地区公路选线的相关要点,采用多种辅助技术,总结出选线原则,最终推荐K线方案为总体最优方案。通过此工程实例,提出在复杂地质岩溶区公路选线的过程中要遵守“多比选,慎选择”的原则、践行地质环保选线原则和“以避为主,避重就轻,动态设计”的设计要点。      

KL植物胶在人工填筑堆石层钻进中的应用

针对伊朗TALEGHAN水库大坝观测仪器孔在松散、架空、透水性极强的堆石层中钻进存在的取心困难、泥浆漏失严重、孔壁稳定性差等问题,引进以KL植物胶为主要原料的处理剂配置成无固相冲洗液和不分散低固相泥浆,并配合一系列堵漏材料在现场的综合应用,取得了良好的钻进效果。介绍了KL植物胶的配方、泥浆性能指标及护壁堵漏效果,为今后类似地层钻孔提供了可借鉴的经验。     

Cohesive Sediment Transport in the Jiaojiang River Estuary, China

Extensive data were obtained of the water and fine sediment dynamics during spring tides in the extremely turbid Jiaojiang River estuary at spring tides. These data enabled the calibration of a two-dimensional (2-D) width-integrated model. Four processes dominated the mud dynamics. These were, firstly, the formation at slack tide of soft mud deposits with an erosion constant much smaller than that of the underlying compacted sediment, secondly the sediment-induced buoyancy effects, thirdly the collapse of the turbulence by the sediment suspension in the fluid mud range and fourthly the inflow of sediment at the mouth of the estuary. These findings demonstrate the necessity to have detailed field data to enable quantitative, as opposed to qualitative, modelling of mud dynamics in turbid estuaries. The estuary is infilling with sediment from the East China Sea and not from riverine inflow, this sediment presumably originates from the Yangtze River located 200 km further north.     

澳门美高梅金殿工程大口径钻孔扩底灌注桩施工技术

澳门美高梅金殿工程主楼基础为38根钻孔扩底灌注桩，桩孔直径为3m扩底到4．2-4．5m，场地狭窄，且是在微风化花岗岩中扩底。根据工程的具体情况，采用贝诺特工法、反循环四翼刮刀钻头钻进、滚刀钻头钻进等组合钻进工艺，同时采用在港澳地区限制严格的泥浆护壁钻进。为港澳地区用泥浆钻桩孔作出了典范，且取得了良好的经济效益。     

泸州深层页岩气呼吸性地层井漏堵漏方法及对策分析——以Y101H3-4井为例

泸州深层页岩气储层埋深达4000 m,属于高压力地层,所钻遇石牛栏组地层岩性为含砂泥岩,本区内多口井钻遇高压裂缝气,溢流及井漏风险大,时常出现高套压事件;同时一些井存在采用高密度钻井液钻进至类似地层时发生漏失后又返吐的现象,给堵漏和钻进作业带来较大困难。针对该类呼吸性地层井漏,以Y101H3-4井为例,现场试验了一系列堵漏方法及措施,结果表明：常规堵漏工艺对呼吸性地层堵漏效果不佳,堵漏材料粒径难以匹配,易导致封门堵漏失败;针对同平台邻井实钻油气显示情况,合理降低钻井液密度有助于堵漏作业实施;油基水泥塞是解决此类呼吸性井漏最有效的工艺技术,但前提条件是确定合理钻井液密度,降低注水泥过程中的返吐量,防止水泥浆与钻井液直接接触污染。在泸州区块采取降密度+注油基水泥塞堵漏是解决呼吸性地层井漏的最佳方法,可快速解决该类地层的堵漏难题。