Earth Drilling Research Articles

Identification of construction sludge generated by earth drilling

Identification of construction sludge generated by earth drilling

Review of High-Temperature Power Electronics Converters

Power electronics converters operating at elevated temperature usually have degraded performance, such as reduced efficiency, lower noise immunity, and decreased system reliability, compared to those operating at room temperature. Nevertheless, harsh-environment applications, such as deep earth drilling, automotive, avionics, and space exploration, have been utilizing converters in high-temperature environments and are continuously pushing the temperature limits higher and higher with the advances in device technologies and converter design methodologies. This article starts with a literature study to identify the temperature dependence and the temperature limits of individual components. Then, published works about high-temperature converters are examined. Their selection of components is compared. Experimental results are analyzed to reflect on the efficacy of different component selections. Finally, since the latest published high-temperature converter was developed more than five years ago, a 1-kV input, 520-V output, 1-kW, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$150$</tex-math></inline-formula> °C-ambient-temperature-rated dc–dc converter is designed with state-of-the-art devices. Based on the literature review, and the test of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$150$</tex-math></inline-formula> °C prototype, the main challenges of designing high-temperature power electronics converters are identified and concluded to be time-consuming, difficult, and expensive characterization of components, lack of accurate and computationally efficient models of converters, and optimizing component selection within short development time.

Circuit Techniques in GaN Technology for High-Temperature Environments

As a wide bandgap semiconductor, Gallium Nitride (GaN) device proves itself as a suitable candidate to implement high temperature (HT) integrated circuits. GaN500 is a technology available from the National Research Council of Canada to serve RF applications. However, this technology has the potential to boost HT electronics to higher ranges of operating temperatures and to higher levels of integration. This paper summarizes the outcome of five years of research investigating the implementation of GaN500-based circuits to support HT applications such as aerospace missions and deep earth drilling. More than 15 integrated circuits were implemented and tested. We performed the HT characterization of passive elements integrated in GaN500 including resistors, capacitors, and inductors up to 600 °C. Moreover, we developed for the first time several digital circuits based on GaN500 technology, including logic gates (NOT, NAND, NOR), ring oscillators, D Flip-Flop, Delay circuits, and voltage reference circuits. The tested circuits are fabricated on a 4 mm × 4 mm chip to validate their functionality over a wide range of temperatures. The logic gates show functionality at HT over 400 °C, while the voltage reference circuits remain stable up to 550 °C.

Underwater plasma breakdown characteristics with respect to highly pressurized drilling applications

Deep earth drilling is a key technique to extract oil, gas, and geothermal heat from the earth. Many complex energy focusing methods have been explored as an alternative approach to reach these resources but most of them require high energy. However, by utilizing short time span liquid plasma discharges, energy focusing can be achieved within traditional drilling systems. These discharges induce a rapid expansion process and a resulting shockwave. It is believed that this focused energy will lower the required cutting force to progress through the rock. Lowering the required cutting force will allow for lower drill bit wear, quicker rate of penetration, and an overall cost savings of the project. Plasma breakdown characteristics at drilling relevant pressures, ranging from 1 to 350 atm, were studied. A resistance–capacitance circuit with an air gapped spark switch was utilized to generate pulsed plasma between the pressurized electrodes. It was found that the required breakdown voltage increases as the pressure increases. It was also found that a plasma channel formation and an associated breakdown may or may not occur between the electrodes at different pressures due to variation in required breakdown voltages. Breakdown time-lag in the dielectric medium (tap water, 780 μS cm−1) increased as the pressure was increased, which indicated a higher voltage drop at higher pressures (&amp;gt;100 atm). The plasma generated cavitation bubble with an associated shockwave occurred as pressures were increased. However, the bubble radius and the bubble duration decreased as the pressure was increased. The plasma generated shockwave speeds fall within the expected speed of sound in water. Finally, preliminary rock cracking tests were performed on granite at high pressures (340 and 272 atm) and it was found that plasma is able to create cracks in the rock.

浙西南常绿阔叶林凋落物空间分布及其对土壤养分的影响

凋落物作为养分的有效载体对于森林养分循环具有重要作用。近年来学者们对凋落物开展了大量研究，但森林内部凋落物的空间分布及其对土壤养分空间异质性的作用一直没有得到充分重视。利用位于浙江西南部的百山祖亚热带中山常绿阔叶林5 hm²森林动态监测样地中50个凋落物收集器2009-2017年收集到的凋落物产量数据和相关的地形和土壤养分数据，运用同步自相关回归分析地形和群落结构因素对凋落物及其组分产量的影响，利用多元线性混合效应模型研究了地形和年均凋落物输入量与土壤养分含量的关系。结果表明（1）地形因子中仅凸度与总凋落物以及叶凋落物产量呈显著正相关；（2）邻域内的大树和中树（胸径≥ 5 cm）的平均胸径显著提高总凋落物、叶凋落物和小枝及树皮凋落物产量，而邻域物种数显著提高总凋落物、叶凋落物和繁殖器官凋落物产量；（3）地形凸度与表层（深0-10 cm）土壤有机质含量显著正相关，但与近表层（深10-20 cm）土壤总氮、有效磷和速效钾含量显著负相关；（4）凋落物输入量显著提高表层（深0-10 cm）土壤的碱解氮和有机质含量。总体来看，百山祖常绿阔叶林凋落物产量的空间变异受到地形和森林群落结构因素的制约，并影响林内土壤养分的空间异质性。;Litter, as an effective carrier of nutrients, plays an important role in forest nutrient cycles. In recent years, several studies have been carried out on litter; however, the spatial distribution of litter yield in a forest and its effects on the spatial heterogeneity of soil nutrients have not been thoroughly investigated. In August 2008, 50 litter traps with horizontal areas of 0.71 m×0.71 m along a path in the 5hm² forest dynamics plot in the Baishanzu midmountain subtropical evergreen broadleaf forest were set and all the litter falling into the traps was collected twice a month during a period from 2009 to 2017. The litter was dried in an oven at 80℃ at a constant weight and was weighed. In July 2014, soil samples were collected using an earth drill from three 1m×1m quadrats with an adjacent distance of 2 m for each of the 50 litter traps (50×3 samples). Each soil sample was divided into surface and near-surface layers (i.e., 0-10 cm and 10-20 cm, respectively). Total nitrogen, alkaline nitrogen, available phosphorus, available potassium, and organic matter contents of these soil samples were determined by common soil chemistry approaches. The elevation, convexity, and slope of each 10m×10m quadrat were assigned to the trap located in the quadrat. Simultaneous auto-regression was used to analyze effects of topography and community structure on the litter and its component yields. The community structure was described according to the total basal area, mean diameter at breast height (DBH), and species richness of trees with DBH ≥ 5 cm in the 5 or 10 m radius neighborhood of the traps. Further, the impact of the topography and annual litter input on the soil nutrient concentration was studied using a linear mixed effect model. The results showed that (1) only convexity was positively correlated with the total and leaf litter yields; (2) the mean DBH of the trees in the neighborhood significantly increased the total, leaf, twig and bark litter yields, while the number of species in the neighborhood significantly increased the total, leaf, and reproductive organ litter yields; (3) the terrain convexity significantly increased the soil organic matter content in the surface layer (0-10 cm deep) but significantly reduced the total nitrogen, available phosphorus, and available potassium contents in the near-surface layer (10-20 cm deep); and (4) the total litter input significantly increased the alkaline nitrogen and organic matter contents in the surface soil. Our results suggest that the spatial variation in the litter yield in the Baishanzu evergreen broadleaf forest is determined by the topography and forest structure and affects the spatial heterogeneity of soil nutrients in the forest.

Identification of Construction Sludge Generated by Earth Drilling

Identification of Construction Sludge Generated by Earth Drilling

The optimization of pressure controller for deep earth drilling

Obtaining samples of deep in-situ conditions is first step to explore the mysteries of the earth requires. In view of the current problems of insufficient pressure maintaining capacity of the existing equipment, we independently developed the in-situ fidelity coring system and designed the osmotic pressure controller based on the geometry of square cover. The finite element method is used to analyze the pressure maintaining capacity of the pressure controller. It is found that it would produce large deformation and stress concentration when the pressure was applied on, resulting in low pressure maintaining capacity. Then the structural optimization schemes of conical sealing contact surfaces with 25?, 35?, 40?, and 45? apex angles and spherical sealing contact surface are proposed, and the spherical contact surface structure is found to be optimal. Finally, the material is optimized, and a higher strength material such as 45CrNiMoVA alloy is used. Based on the pressure controller with spherical contact surface, the pressure maintaining capacity increased to nearly 70 MPa. The research results obtained in this paper provide the basis for the development of the coring system, the deep exploration of the earth and the establishment of rock mechanics theory.

Low Power Silicon Carbide RS-485 Transceiver

Abstract This paper describes the first RS-485 transceiver for high temperature applications designed in SiC-CMOS. The transceiver was designed and developed in a 1.2μm CMOS HiTSiC® process from Raytheon UK. It has been tested at a voltage supply of 15 V from temperatures of 25°C to 400°C. At 320°C, the rise and fall times are 40 ns (for both), and the propagation delay from driver to output high and to output low is 150 ns and 50 ns respectively. The transceiver has been demonstrated to operate over 700 m of Cat5 cable. A high temperature data acquisition and transmission system has potential applications such as deep earth drilling, remote connection to high temperature locations, and high temperature data acquisition.

Axial Load Capacity of Cast in Place Piles from SPT and CPTU Data

This paper aims to deal with the assessment of axial load capacity for cast in place pile foundations, which are made by the earth drill method, by using the data taken from Standard Penetration Tests (SPTs) and Piezocone Penetration Tests (CPTUs). These tests were carried out as part of the investigation program for P.N.G. Terminal-Power Plant, near Semani beach, in Hoxhara marsh, in the western part of Albania. The design of axial load capacity of piles is based on empirical formula using SPT and CPTU values. This study presents the results of axial load capacity analysis of cast in place piles by different analytical calculation methods, which are based on in situ tests results, and also referring to the Building Standard Law of Japan. In the end of our work, differences between calculations methods by using different in situ tests results are shown in tables and graphs.

기계굴착공법을 적용한 현장타설말뚝 시공시 부조화 발생요인 분석 및 대응 방안

현재 기계굴착공법인 올케이싱, 어스 드릴, 역순환공법이 널리 활용되고 있음에도 불구하고, 시공 현장에서 발생되는 부조화로 인하여 말뚝의 품질이 저하되거나 부실시공이 빈번히 발생되고 있다. 본 연구에서는 이 문제를 줄이는 방법으로 올케이싱, 어스 드릴, 역순환공법을 중심으로 현장 콘크리트타설 말뚝 시공시 발생되는 부조화 종류별로 부조화 발생요인을 현장기술자들을 대상으로 설문조사를 수행 하였다. 그리고 설문분석결과를 토대로 부조화 종류별로 빈번히 발생되는 부조화 요인을 분석함으로서 대응방안을 제시하였다. 본 연구에서 분석된 자료는 향후 건설현장에서 기계굴착공법으로 시공될 때, 부조화를 최소화 할 수 있는 효과적인 자료가 될 것으로 사료된다. Although a range of machine excavation methods are in wide use, including casing, earth drill and reverse circulation drilling, deterioration in pile quality and faulty construction can be often found these days because of trouble in the construction field. For this study, research was conducted in the form of a survey of construction engineers working in the field in order to identify the types and the causes of trouble by focusing on all casing, earth drilling and reverse circulation drilling. By analyzing the causes of trouble, countermeasures could be presented. The data and the analysts presented in this study could be effectively used for minimizing trouble in future machine excavation work during construction.

Improvement on earth bearing capacity at base of in situ earth drill pile for Chao Phraya river crossing, Dao Kanong cable-stayed bridge project : Shinkai, J Proc Int Conf on Cable-stayed Bridges, Bangkok, 18–20 Nov 1987V2, p1387–1396. Publ Bangkok: AIT, 1987

Improvement on earth bearing capacity at base of in situ earth drill pile for Chao Phraya river crossing, Dao Kanong cable-stayed bridge project : Shinkai, J Proc Int Conf on Cable-stayed Bridges, Bangkok, 18–20 Nov 1987V2, p1387–1396. Publ Bangkok: AIT, 1987

SIPRE Ice-Corer for Obtaining Samples from Permanently Frozen Bogs

Discusses the effectiveness of sampling devices demonstrated by summer 1962 field use in northern Yukon and laboratory tests in Mar. 1963. Hand drilling in Yukon Territory produced excellent cores, but the cutting teeth in the ice-corer were quickly dulled from mineral matter; holes 7-8 ft deep required three hrs drilling. Tests with power drives indicated that a two-man team could core a frozen bog 8 ft deep in 30-45 min. The two types of power units tested: a McCulloch chainsaw motor, and a Haynes earth drill, were both adequate; details are given.

Earth Drill Proposed

Earth Drill Proposed