| Earth is the survival of mankind and the resources are the basic of our society.Exploring the deep-earth is one of the key ways to solve the problem of resources,energy and environment.At present,the depth of oil and gas exploration has reached to 10 km,and the scientific drilling got more than 12 km.With the depth increasing,the formation temperature rises with the rate of 30?/1000 m,which means the temperature will exceed more than 300? on the bottom of 10 km well?Hot dry rock,buried in kilometers underground and with more than 150? temperature,is considered as the key new energy to substitute fossil energy by many countries.However,both the ultra-deep drill and hot dry rock exploration and development need to drill in high temperature formation.The drill bit is always in the forefront and core position in drilling technology and drill process.Diamond drilling is a kind of advanced rotary drilling technology,which is widely used in drilling.It is also the main drilling method adopted in scientific drilling and hot dry rock development.With the increase of temperature,the characteristics of rock will change greatly,such as strength,drill ability,and thermal properties.Meanwhile,the high temperature influents the drill technique a lot,such the drilling fluid capacity decreases,the stead ability loses,and bit gets more wear.Diamond will get damaged under high temperature.However,until now research on diamond drilling under high temperature is rare and it is still unknown about the characteristics of high temperature diamond drilling.In this thesis,based on the diamond materials,rock,circulation fluid,test equipment and methods,the influence of temperature on diamond drilling were studied and the regular pattern was revealed.The main contains and conclusions are listed as below.1)Comprehensive test and analysis were conducted to study the performance of diamond bit materials under high temperature condition.The results of thermogravimetric analysis showed that these three kinds of diamond materials have obvious thermal effect at the degree of 700?.The results of strength test on real time high temperature condition showed that the bending strength of impregnated diamond materials increased firstly and then got decreased at 100?.After heating treatment(from room temperature to 1000?),the bending strength,wear resistance,and static pressure strength decreasd with temperature and the downward trend got accelerating from 600?.2)A high temperature drilling simulator was developed.The simulator can heat the rock to 300? for drilling.3)The materials and methods were completed and some ralated computing work was carried out.Three kinds of rock were selected,including granite,basalt,and sand stone.Two impregnated diamond bits and two PDC bits were designed and manufactoried.The high temperature circulation medium was screened and tested.The heat transfer function of Solidworks Flow Simulation was applied to analyze the rock heating process and the time length required to heat the rock to a stable uniformity temperature are obtained.4)High temperature(up to 300?)diamond drilling experiments were conducted.The results of impregnated diamond drilling showed: The rate of penetration(ROP)increased by 25% for granite,7% for basalt and 50% for sandstone under 300?,compared with that of room temperature.In the analysis of the torque data,the torque increased by 25% for granite,that of basalt decreased by 11% and that of sandstone increased by 18%.The results of PDC drilling experiment showed: The ROP of PDC bit in sandstone increased from 4.1m/h to 13.8m/h under high temperature(300 ?),compared to that of under room temperature.The ROP of PDC bit in basalt and granite was very slow and got decreased hughly under 300?.The overall results show that the diamonds diamond bit is suitable for drilling at 300 ? high temperature in hard rock formation.PDC bit still does not apply to drilling granite and basalt and other hard rock under 300? condition. |
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