Respirable coal mine dust (RCMD) particles, particularly the nano-sized fraction (<1 μm) of the RCMD if present, can cause severe lung diseases in coal miners. Characterization of both the particle size and chemical composition of such RCMD particles remains a work in progress, in particular, with respect to the nano-sized fraction of RCMD. In this work, various methods were surveyed and used to obtain both the size and chemical composition of RCMD particles, including scanning electron microscopy (SEM), scanning transmission electron microscopy (S-TEM), dynamic light scattering (DLS), and asymmetric flow field-flow fractionation (AsFIFFF). It was found that the micron-sized fraction (>1 μm) of RCMD particles collected at the miner location, from an underground coal mine, contained more coal particles, while those collected at the bolter location contained more rock dust particles. Two image processing procedures were developed to determine the size of individual RCMD particles. The particle size distribution (PSD) results showed that a significant amount (~80% by number) of nano-sized particles were present in the RCMD sample collected in an underground coal mine. The presence of nano-sized RCMD particles was confirmed by bulk sample analysis, using both DLS and AsFIFFF. The mode particle size at the peak frequency of the size distribution was found to be 300–400 nm, which was consistent with the result obtained from SEM analysis. The chemical composition data of the nano-sized RCMD showed that not only diesel particles, but also both coal and rock dust particles were present in the nano-sized fraction of the RCMD. The presence of the nano-sized fraction of RCMD particles may be site and location dependent, and a detailed analysis of the entire size range of RCMD particles in different underground coal mines is needed.
China, Modernisation, Modernity, Postmodernity, Postcolonialism, Culture studies, Cross-cultural transfer, EU-China relations, Comparative sociocultural studies, Critique, Paradigms,
The 21st-century construction of a new Chinese political discourse faces the same dilemma that Chinese intellectuals first identified in the 19th century – how to make currently pre-eminent Eurocentric sociocultural, economic and political theory and praxis compatible with Sinocentric sociocultural, economic and political circumstances. At the same time, among Chinese thinkers and strategists, there is a growing self-confidence in China’s ability to play a pre-eminent role in a new post-Western world order. Euro-American faith in the convergence of all societies into a single economic, social and political model defined by the heritage of the European Enlightenment and by Euro-American history is challenged by the emergence of new economic powers outside the Euro-American sphere that resist this model. Eurocentric sociocultural, economic and political theory and praxis must adapt themselves to the emerging paradigms and praxis of an emerging multicultural world order. During a historical period when Afro-Eurasian connectivity was at its height and Ibn Battuta and Marco Polo traversed Eurasia, Ramon Llull (1232–1316) tried in his Ars Magna Generalis (ca. 1274) to develop a new common and consensual terminology and logic of key terms and beliefs that would facilitate mutual understanding among Christians, Jews and Muslims. Shortly thereafter, in his Muqaddimah, Ibn Khaldun (1332–1406) elaborated a universal theory of history. Giambattista Vico (1668–1744) tried something similar in Principi di Scienza Nuova d’intorno alla Comune Natura delle Nazioni. The development of new cross-cultural paradigms on a common, multicultural and consensual basis is needed, based on better knowledge of the non-Euro-American languages and cultures involved and more collaborative international and multicultural efforts to promote and build better mutual knowledge and understanding. Mutual respect requires mutual knowledge in order to construct a common and consensual multicultural civic discourse that could lead to more innovative and productive paradigms and more meaningful cooperation.
This paper describes the preparation and operation for the first use of a riserless mud recovery (RMR) system on the top-hole section of a well in the Gulf of Mexico. The material includes pre-well engineering and preparations including hydraulic analysis, pre-job vessel inspection, construction of new equipment, installation, pre-well planning decisions, and rationale for decisions. In addition also discussed are benefits including improved wellbore quality due to use of an engineered drilling fluid, logistics savings from reduction of drilling fluids, and minimized environmental impact. The paper also includes descriptions of equipment installation and testing onboard the drilling vessel operations during drilling, problems encountered and lessons learned from the operation. A description of all equipment is included in the paper along with specifications and operation parameters. An RMR system has application in the top-hole drilling of oil and gas wells. Using conventional methods, drilling fluid pumped down the drillstring during operations flows out onto the sea floor; this is often referred to as " Pump and Dump??. RMR collects the mud at the mud line and pumps the fluid back to the rig where it is reconditioned and reused. It allows the use of engineered drilling fluids and has possible applications for all offshore drilling. RMR was deployed on a dynamically positioned vessel, and successfully used to drill the 26-in. hole section. Drilling fluid recovered from the mud line back to the drillship was processed and reused, resulting in significant reduction in the volume of mud required for this top-hole section. RMR reduced costs through savings in drilling fluid and improved well construction. RMR is applicable to the drilling of top-holes in the entire Gulf of Mexico. It has significant potential to reduce top-hole drilling costs, eliminate casing stings, extend casing shoe depths, drill through and past problem formations and improve the wellbore by eliminating washouts and shallow hazards. Introduction Operators continue to explore and develop fields at increasing water depths. In certain offshore areas where younger sedimentary rocks are deposited, there is often a very narrow margin between formation pore pressure and fracture pressure that creates tremendous drilling challenges (Rocha and Bourgoyne, 1994). The solution to this narrow operating window is to develop techniques that extend the casing setting depths more efficiently. The use of a riserless drilling technique, dynamic kill drilling (DKD), has been instrumental in successfully pushing the casing depths deeper in deepwater applications (Johnson and Rowden, 2001). The DKD methodology employs the dual gradient drilling concept, consisting of the seawater hydrostatic above the mud line with the ability to vary the hydrostatic below the mud line by drilling fluid weight variations. This functional control of the drilling fluid density is tremendously advantageous while drilling shallow gas or water flows from over-pressured formations where large washouts, caves, formation compaction, and collapse could occur (Pelletier et al., 1999). This technique has been repeatedly employed in challenging deepwater projects where the initial upper hole sections were extended to obtain the required leak-off tests (LOTs).
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