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Analysis of the Mud Escaping of HDD and R&D for Preventing Mud Escaping Software

Author: LiuJie
Tutor: ZhangXiaoXi；WuXiaoMing
School: China University of Geosciences
Course: Geological Engineering
Keywords: HDD mud escaping mud design
CLC: TE973
Type: Master's thesis
Year: 2009
Downloads: 169
Quote: 2
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Abstract

With the development of West-East Gas Pipeline project and the urban underground pipeline network infrastructure,Horizontal Directional Drilling(HDD) technology applications become more widespread.But the actual situation encountered by the project are more and more complex, which make HDD technology become more and more sophisticated to overcome these engineering problems along with HDD technology widely used at the same time.In HDD project,spoils can be removed to the ground surface through themud system.The pumped mud could flow to ground surface through pores and cracks which are natural defects of ground.That phenomenon is called mud escaping.The mud escaping was in the way of HDD development,and it was bad to HHD project as follow:(1)When mud escaping occurred,mud seeped into formation.So the stress of formation was changed that would be bad to borehole stability.(2)The mud escaping led to mud flowing on ground.Because there was chemistry component in the mud,it would pollute the environment and damage the farmland.(3)When mud escaping was severe,formation would be destroyed and it brought hidden trouble to roads,buildings and underground constructs.(4)the cost of project was increased as the mud escaping.The mud escaping of HDD was been attention recently and inside and outside scholar researched in the way of summarizing experience.This paper research the mud escaping basing on the follow:(1)Penetration damage model for the mud escapingFor the mud escaping,this article sets up two models according to the time and path of percolation respectively,which are:the model of time factor impacting on the percolation process and the model of path factor impacting on the formation damage.From the analysis of the time factor impacting model,under the condition of the percolation channel,which is formed of formation pore,has not been plugged,the time required for the mud escaping occurring is inversely proportional to the soil penetration,proportional to the power of 3/2 of the horizontal depth of borehole,and approximately proportional to the pressure of the mud.From the analysis of the path factor impacting model,the form of mud escaping occurring is forming new channels after damaging the soil formation under the condition of the percolation channel has been plugged. Whether the mud escaping occurs depends on the ratio of the greatest pressure which the soil formation bears and the pressure of the mud.The mud escaping occurs when the mud pressure is greater than the critical damage pressure of soil formation.(2)The mud escaping experimentThrough the analysis of properties of geotechnical particles and properties clay powder in HDD,we design mud escaping experiment using sand as medium,and conform that the proportion of clay powder in mud,additive content of mud and the size of formation particle has impact on permeability in HDD.We also design the plug experiment with mud,and get the conclusion:mud easily plugs the percolation channel of formation when the diameter of formation hole less than 20μm.In addition,mud additives could improve the diameter of formation hole which can be plugged by mud.(3)The design of mud for preventing mud escapingThrough the analytical result of mud circulating depressurizing theory,it can be known that after adjusting the mud performance parameters,the pressure of mud in the borehole will be changed,and pressure release of mud can prevent the occurrence of mud escaping.In this paper, experimental research has been done on mud design by means of three aspects which are high-shear dilution theory and experiment/plugging principle and formula optimization/treament of water for mud.As well as,mud formulations have been designed which could prevent the mud escaping occurring.(4) Software DesignBased on the theory of mud escaping and the mud design method of preventing mud escaping, we developed a mud design software,the main purpose of this software was to prevent mud escaping.The software’s main framework is MFC,which can be widely compatible with.The software is user-friendly and easy-operation.And it was used in the North Canal project,the results show that the software was reliability and accuracy.Finally,the study was summarized and some relevant conclusions were raised at the last of this paper,furthermore,the paper raised some ideas and advice for the further study.

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