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Abstract:This paper comprehensively summarizes the important achievements made by Institute of Exploration Techniques， CAGS on directional drilling technology and survey tools， deep drilling technology and equipment， offshore drilling technology and equipment during the 13th Five-Year Plan. These achievements mainly include innovations in directional drilling and well intersection technology which has helped the second-round offshore natural gas hydrate production test realizing a leap from “exploratory production test” to “trial production test”； organization and implementation of Well SK-2 scientific drilling project where significant breakthroughs have been made on theory， technology， engineering and equipment； development of the first domestic deep sea wellhead suction anchor which has solved the insufficient support problem with the wellhead in deep sea shallow soft stratum. Moreover， this paper also analyses the existing problems and challenges with an outlook made on the institute’s future research activities in the coming 14th Five-Year Plan.

Abstract:The successful launch of the “Chang’e 5” probe has opened the prelude to the return of samples from the moon in China. To meet the current requirements of lunar （or deep space in future） exploration， drilling technology， as the most commonly used method to obtain deep geological samples， is receiving more and more attention. However， in the face of the extreme environment of the moon （or deep space in the future）， the earth’s conventional machinery and craftsmanship cannot be directly transplanted. Therefore， this paper has conducted surveys and statistics on the current progress of lunar drilling technology in various countries， including several areas such as researching the properties of lunar soil， developing of lunar soil simulant， the impact of lunar environment acted on drilling， the structure and parameters designed for lunar drilling equipment， and optimization of lunar drilling regulations， and conducted thinking of future lunar drilling.

Abstract:Over recent ten years， the drilling footage in in-situ leachable sandstone-type uranium exploration in China has been increasing steadily， and uranium exploration is shifting to new stratums， new areas， new types and new depth； thus， new requirements are raised for in-situ leachable sandstone-type uranium drilling technology and equipment. This paper analyzes the current status of in-situ leachable sandstone uranium drilling， and proposes a series of improvement measures to improve drilling efficiency from the aspects of technology and equipment. The main measures include implementation of parallel operation of core removal at surface and core drilling， utilization of low-solid polymer mud， optimization of the bit and drilling tool assembly， application of the swivel type double-tube core barrel and large diameter wire-line core drilling technology in loose strata， execution of full-face drilling technology. Besides， automatic and digital drilling equipment should be developed to promote the industrial level of drilling engineering.

Abstract:China is planning to drill an extra deep borehole with a depth of 13000m which will exceed the depth of 12262m of the Russian Cola super-deep borehole. However， it faces huge challenges to drill into the depth. Besides drill equipment and tools， the drilling process and the drilling procedure also determine if drilling is successful or not. At present the drilling process and the drilling procedure are mainly guided by and depend on the data shown at surface devices. However， the data may deviate from the real values of downhole parameters， which will influence directly improvement of technical and economical indexes of deep drilling accordingly. Professor of Russian Astrahan State Technical University Esaulenko V. N. and others have designed an automatic measurement and control system of downhole parameters， in which the sensors are necessary and critical devices. This paper introduces the sensors for downhole parameter measurement and takes the design of the azimuth sensor as an example to demonstrate how to design the measurement system， which would be useful for improving future ultra-deep borehole drilling in China.

Abstract:Air reverse circulation drilling technology， which has advantages of fast drilling speed， low energy consumption， continuous core sampling without tripping and effective prevention of circulation loss in snow cover， sees great potential application in ice drilling. In view of the characteristics of ice drilling technology， this paper proposes three kinds of air reverse circulation ice drilling techniques， including dual-wall drill pipe， double channel high pressure hose and parasitic high pressure hose； and describes their working principles and characteristics respectively. Analysis is made of the suspension velocity of ice particles in air medium with the suspension and transport equations for both the single ice particle and the particle group established under the guidance of pneumatic transportation and gas drilling theory. Meanwhile， the experimental bench was designed to test the air speed required for ice chips suspension. The calculated values are in good agreement with the measured values with the maximum difference at about 10.91%. The results showed that the ice particle size， ice particle density and air volume are the key factors affecting the suspension and up-hole velocity. The equation for ice chips movement established in this paper can be used to calculate the air volume required to carry ice chips during actual drilling， providing a basis for the subsequent implementation of air reverse circulation ice drilling technology in the polar regions.

Abstract:China has abundant oil shale which is a potential oil and gas resource and important strategic resource to ensure national energy security. In-situ exploitation is the development trend of the oil shale industry. Through a systematic data collection and investigation， the development process of oil shale in-situ exploitation technology is summarized. The main technical characteristics and development status of four kinds of heating technologies， including conduction heating， convection heating， radiation heating and reaction heating technologies， and five kinds of reservoir reconstruction technologies， including hydraulic fracturing， underground blasting， freezing wall， grouting curtain and gas injection barrier underground space sealing technologies， are further analyzed. According to the characteristics of China’s oil shale resources， three key technologies that must be broken through and adopted for the in-situ exploitation of oil shale are proposed. The first is the high-efficiency heating technology with multiple heating， high efficiency downhole heater and catalytic efficiency as the core. The second is the horizontal well steering drilling technology with rotary steering drilling and precise distance measurement guiding for dual well as the keys. And the third is the composite reservoir reconstruction technology with CO₂ dry fracturing， acid fracturing and gas injection barrier underground space sealing technologies. It is hope that this work could provide some reference for the in-situ exploitation technology of oil shale in China.

Abstract:In recent years， nano-silica has attracted extensive attention in the oil and gas industry due to its ultra-high specific surface area and pozzolanic reaction with cement. In this paper， the research status of nano-silica in cementing slurry is systematically reviewed with focus on the effects of nano-silica on the water loss and thickening time of cementing slurry， and on mechanical properties and microstructure of hardened cementing slurry as well. The effects of nano-silica on the performance of cementing slurry under high temperature is also summarized. The existing problems， challenges and future development direction of nano-silica application in cementing slurry are discussed so as to provide some suggestions and ideas for the development and application of nano-silica in the cementing field.

Abstract:How to mine hot dry rock， which is a kind of renewable clean energy， is of great significance； however， both the temperature and depth of hot dry rock makes it difficult to exploit hot dry rock geothermal resources. In the mining process， reservoir construction is one of the key technologies. Reservoir construction produces a large-scale volumetric fracture network to ensure a large area of heat exchange channels for long-term thermal energy extraction. As a new method， the carbon dioxide blasting fracturing technology provides new ideas for reservoir construction. This paper briefly describes the carbon dioxide blasting fracturing technology， as well as the internal relationship between the amount of carbon dioxide charged， the amount of activator， and the thickness of the rupture disc during the blasting process. The carbon dioxide fracture initiator used in the construction of hot dry rock geothermal reservoirs is optimized. The specific parameters of the internal structure of the initiator have been designed， and the external structure and overall system have been improved. Finally， a new type of carbon dioxide initiator that can be used in the construction of hot dry rock geothermal reservoirs is developed， which provides effective technical means for the construction of hot dry rock geothermal reservoirs， and fills the gap in the field of downhole carbon dioxide fractur initiators that are resistant to high temperature and pressure.

Abstract:Coal mine tunnel drilling equipment and technology are restricted by many unfavorable conditions in the process of development， which leads to the lag of new technology development. The promotion of intelligence in China’s coal mines brings a revolutionary opportunity for the development of coal mine tunnel drilling equipment and technology. The foreign technical characteristics and development of drilling equipment are analyzed. At the same time， the paper also analyzes the three development stages of domestic tunnel drilling equipment and technology： the initial stage of the split type drill rig and the trajectory control method with the stable combined drilling tools； the vigorous development stage of the crawler drill rig， the directional drilling equipment and technology， and the soft coal seam drilling technology； the new development stage of the automatic and intelligent equipment and technology. The key problems are put forward with drilling equipment and technology in the intellectualized development stage of China’s coal mines in the future， which provides support for improving the intellectualized level of drilling equipment and technology.

Abstract:The mast is an important part of the drill. This paper describes the structural design of the mast of the 4000m core drill independently developed by Institute of Exploration Technology. In order to ensure that the mast meets the requirements of working conditions such as strength， wind load， the mast model is created with SolidWorks， and ANSYS Workbench is used to carry out the finite element analysis for the mast assembly to verify the strength and rigidity of the mast structure， and perform the modal analysis to obtain the first 10 intrinsic vibration frequencies and modes. They are compared with the excitation sources， and the results show the first and second intrinsic frequencies overlap with the frequencies of the drilling turntable and hoisting system， which may cause resonance； thus， the rotating speed of the drilling rig turntable and hoisting system is adjusted to avoid resonance. As a result， the deformation amount is small at the maximum deformation position during vibration， indicating that the mast structural design is reasonable， and can meet the actual application requirements； therefor it has some value in engineering application.

Abstract:Drilling technology is the only scientific method that can directly obtain formation samples in the investigation of contaminated sites. Direct push drilling technology has the advantages of no drilling fluid， flexible maneuverability， fast drilling speed， and small sample interference. Based on the existing domestic and foreign study， this paper compares and analyzes the structure and propulsion process characteristics of the Spanish TEC15 and the United States 7822DT rigs. The latter has higher static propulsion and pull-out force. Single pipe and double pipe are studied， and the structural composition and sampling process of the two direct push drilling tools. The results indicate that because the PVC sampling sleeve is set in the single pipe， the integrity of the soil sample can be effectively maintained and the efficiency is high. Nuclear magnetic resonance （NMR）， soil hydraulic testing （HPT）， membrane interface detection （MIP） technical principles and equipment composition are introduced， and MIP has greater technical advantages for the three-dimensional concentration detection of pollutants. The development status of domestic direct push drilling technology and equipment is also analyzed， combined with the geological conditions of contaminated sites in China and research status， pointed out that the portable integrated equipment and technical verification of advanced drilling and in-situ detection that can achieve precise control is the main development trend.

Abstract:Drilling is an important technical means of engineering geological investigation. The engineering geological data obtained by drilling is an important basis for the planning， design and construction of water conservancy and hydropower projects. In recent years， drilling technology and related equipment has been continuously innovated and developed with implementation of water conservancy and hydropower projects. The main contents of this paper include： water pressure while drilling test technology， self-vibration pumping test technology， drilling and sampling technology for sand layers， soft soil layers and gravel layers， large angle inclined hole drilling technology， sonic drilling technology， full hydraulic power head drilling machines， shallow water drilling technology and water conservancy and hydropower curtain grouting automatic recorders. Proper selection and usage of the technology and equipment will produce great social and economic benefits for optimization of these water conservancy projects. This paper also analyzes and envisions the development trend of drilling technology for water conservancy and hydropower projects.

Abstract:Turfy soil in the seasonal frozen area is a special soil containing a large amount of undecomposed fiber residues formed by the accumulation of plant residues in the swamp environment under the action of oxidation and decomposition. The turfy soil fiber and its content have an important impact on the strength and deformation characteristics of turfy soil. At present， the research on the constitutive relationship considering the influence of fiber content on the strength and deformation characteristics of turfy soil is relatively scarce. The K-G constitutive model is widely used for nonlinear theoretical and numerical calculation analysis in geotechnical engineering because the model parameters can be directly connected with the bulk modulus and shear modulus of soil. Taking turfy soil with different fiber content as the research subject， the stress-strain curve of turfy soil was studied by triaxial shear test， and the nonlinear K-G model parameters of turfy soil were obtained. The linear function relationship between model parameters and fiber content was established. It can provide some guidance for actual highway construction.

Abstract:The effects of initial saturation on freeze-thaw damage on red sandstone were studied by physical and mechanical experiments before and after freeze-thaw cycles. The initial saturation of the red sandstone samples was set as 20%， 40%， 60%， 80% and 100%， and the number of freeze-thaw cycles was set as 20. The mass and p-wave velocity were measured， and uniaxial compression tests were conducted of the sample before and after freeze-thaw respectively. The experimental results showed that： （1）After freeze-thaw， the physical properties of red sandstone with different initial saturation have changed with the p-wave velocity decreasing， and the mass loss rate increasing. （2）With the increase of saturation， the uniaxial compressive strength and elastic modulus of the sample tend to decrease after freeze-thaw， but only when the saturation is greater than 60%， the decreasing trend is more obvious. （3）With the increase of saturation， the freeze-thaw coefficient decreases gradually. The study can provide theoretical basis and experimental basis for construction of geotechnical works and monitoring and control of geo-hazards in the cold region.