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71.
72.
通过在水基钻井液中添加纳米氧化物颗粒,来改善其润滑性能。选用了Al2O3、TiO2及SiO2三种纳米氧化物颗粒作为钻井液改性添加剂,利用极压润滑仪及销盘摩擦磨损实验仪研究了添加不同种类和浓度纳米颗粒氧化物对水基钻井液的润滑性能及减摩效果的影响。结果表明,所添加的3种球形纳米颗粒均有润滑减阻减摩的效果,其中SiO2颗粒的钻井液的润滑性能、滤失性能以及减摩效果都是最好的。当纳米SiO2颗粒加量为0.4%时,滤失量最小,润滑系数降低率达到15.6%,摩擦系数降低率为32.0%,磨痕轨迹平滑,减摩效果最为明显。当纳米颗粒浓度超过0.5%时,减摩效果降低,磨盘脱层磨损明显。 相似文献
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南大洋太平洋扇区中尺度涡旋的统计特性及其变化 总被引:1,自引:0,他引:1
中尺度涡旋在南大洋海洋动力学中具有重要地位,其对气候变化的响应表现也引起了海洋学家与气候学家的广泛关注。本文利用涡动动能与涡旋自动探测技术两种方法对南大洋太平洋扇区的涡旋特性及其变化进行了分析。与前人结果相一致的是,高值的涡动动能主要集中在南极极锋海区,并且自西向东逐渐减弱。在过去的20年里,涡动动能在太平洋扇区的显著增强也集中在中西部海域,这里也是南极绕极流斜压性较强的海域。涡旋统计特性揭示了涡动动能的空间分布及其年际变化主要归因于涡旋振幅与旋转速度,而并非涡旋个数或者涡旋半径。这些结果进一步确认了对应于南半球环状模正位相的绕极西风异常改变了南大洋的涡旋特性,从而表现出涡旋活跃性增强。 相似文献
74.
ZK001井钻遇地层为大段泥岩,部分地层为页岩、含盐泥岩、盐膏层。在泥页岩地层进行大口径全面钻进,钻速较快,固控设备能力有限,引起钻屑中粘土颗粒重复性膨胀、软化及裂解分散,最终可能造成粘土侵,对井内安全造成威胁。深部岩膏层易溶于水,从而导致盐层蠕变、井径扩大、井壁失稳等问题。以ZK001井为例,通过优化钻井液体系及现场施工工艺,解决了地层强造浆、盐层失稳等问题。通过岩石力学测试、阳离子交换容量测试、钻井液体系优选及性能测试,确定了上部地层采用聚合物钻井液体系,下部含盐层取芯钻进转换为饱和盐水钻井液体系。通过选用合适的钻井液密度、粘度、切力量、滤失量、含盐量等指标,可以有效控制上部泥岩井壁稳定、含盐层蠕变、井径扩大的问题。钻进过程中钻井液性能稳定且易于维护,从而保证了钻进工作安全、高效、顺利的进行。 相似文献
75.
Jonas Hein Soeryo Adiwibowo Christoph Dittrich Rosyani Endriatmo Soetarto Heiko Faust 《The Professional geographer》2016,68(3):380-389
The recent expansion of protected areas and oil palm plantations in Jambi (Sumatra), Indonesia, has been notably disruptive. This article investigates the scalar dimensions of land conflicts within a privately managed conservation area. We built on qualitative research focusing on struggles related to the formation of two informal settlements within the conservation area. Results indicate that, especially in the context of rapid rescaling (e.g., decentralization), new power constellations emerge, thereby altering preexisting property relations. We argue that competing scales of meaning and regulation are structuring the ability of actors to access land and, consequently, reflect tensions between structure and agency. 相似文献
76.
This paper examines the distribution of unconsolidated sediment in the KwaZulu-Natal Bight located along the east coast of South Africa. Results show that there is a general shelf-wide sediment distribution of coarser grain sizes between depths of 60 and 100?m, punctuated by a broad swathe of mud offshore of the Thukela River. Seasonal changes in sediment distribution patterns are small, being restricted to seaward fining on the inner shelf off the fluvial sources. Sediment distribution reflects a partitioning between sediment populations that are current- influenced and relict (palimpsest) populations associated with submerged shorelines. Wave ravinement during the deglacial transgression, the reworking of submerged shorelines during sea-level stillstands and, to a lesser extent, the Agulhas Current system, are the dominant controls on sediment distribution. 相似文献
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79.
《China Geology》2018,1(2):187-201
Songke Well No.2, one of the main part of the scientific drilling project in Songliao Basin, which was drilled 7018 m and acquired the part of cores continuously from the Low Cretaceous to the Carboniferous and the Permian from the 2843 m deep, can be considered as the deepest continental drilling project in Asia. Aiming at the features of longer well sections, larger diameters and multiple spud-ins for coring of Songke Well No.2, this project broke through the “coring in small diameter and reaming in large diameter” spud-in drilling-completion procedures which are always used in large-diameter-well coring for continental scientific drilling projects in domestic and overseas and the drilling method of short-single-cylinder roundtrip footage. At the same time, “coring in the same diameter and completing drilling at one single diameter” was achieved at all φ311 mm and φ216 mm coring sections of more than one thousand meters long, high-efficient operation with “drilling long footage with drill tools combined in multi-cylinders” was achieved at deep coring section. Four world drilling records were created which include more than a thousand meters continuous coring at φ311 mm, and the footage per roundtrip footage at φ311 mm, φ216 mm and φ152 mm is all more than 30 m, all of these breakthroughs reduced at least 300 days for this project; moreover, considering the characteristics of formations that the geothermal gradient is high in the drilled sections and the inside-well temperature is over 240°C after drilling completion, a formate-polymer water-based mud system was developed by compounding attapulgite and sodium bentonite and by adding independently developed high-temperature stabilizer, which can provide critical technical support for successful well completion at 7018 m in the super-high-temperature environment It is the first time that the water-based mud is operated at the working temperature higher than 240°C in China; Besides, considering the high-quality requirement on cores imposed by the project, the method “mechanical cored is charge” to discharge core nondestructively on the ground was worked out, and more than 4000 m scatheless cores were discharged out of the drill pipes while maintaining original stratum structures. 相似文献
80.
30~#矿权区位于菲律宾迪纳加特岛北部,区内发育有红土型镍矿床。本次勘查圈定4处矿(化)体,其中以Ⅰ、Ⅱ、Ⅲ矿(化)体的矿化范围较大,厚度变化系数为45%~50%(相对稳定),经济价值较高。红土型镍矿体平面上呈地毯状展布于地表,厚度受地形控制,富镍矿体分布于矿权区东部的5、6、11、12小区;剖面上从地表向深部矿体为铁质红土层、松散红土层及高岭土化蛇纹石化橄榄岩层。30~#矿权区红土镍矿矿床的形成经历了从普通矿到富矿两个阶段,红土镍矿石属于酸性矿石。 相似文献