Abstract:At present， drilling is the only technical method that can directly obtain subsurface physical data and provide measurement channels， and scientific drilling is an indispensable and important means for human beings to solve the major problems about resources， disasters and the environment. This paper briefly reviews the development of continental scientific drilling technology and equipment. Through the investigation of the frontier issues and development routes of new technology development in continental scientific drilling， summarization is made of the main technical problems which continental scientific drilling faces with the development roadmap of highly integrated， smart green drilling technology put forward for ultra-deep scientific drilling in China， which can provide reference for further development and organization of scientific drilling projects in China.

Abstract:A new kind of nano cement-based plugging material has been developed to meet the actual needs of the performance of wellbore protection materials in deep drilling technology. First， through analyzing the performance results of different types of cement at the same temperature， Grade G oil well cement was determined as cementing material； second， based on the performance defects of deep drilling wellbore protection and plugging material， special fiber and nano materials were used to improve the mechanical properties of cement slurry， and the early strength agent （ZQ） and the water reducer （GB） were selected as additives for orthogonal experiment， which led to the development of the optimum formula of cement based wellbore protection and plugging material. Finally， its main performance was analyzed and evaluated. The results show that the material has good fluidity and excellent mechanical properties， and its comprehensive performance can meet the needs of wellbore protection and plugging in deep drilling.

Abstract:In order to solve the problem of insufficient core recovery in broken formation in Yongshun， Hunan Province， this paper investigates the geological structure characteristics of the exploration area with respect to Well Yongye-2， and analyzes the stratum characteristics based on the core samples from different strata. On the premise of strictly following the drilling design and quality requirements， different drilling fluids were adopted for each section to eliminate collapse and leakage. To deal with insufficient core recovery in broken formations， we developed and used a bladder multi-section bundled wireline core drilling tool. The unique bladder structure， equipped with a leading side jet drill bit， can protect the core from erosion by drilling fluid. Field results showed that when drilling deeper well sections with the well depth from 1055.76m to 1108.96m， core recovery increased to more than 90% from the existing lowest 79%， and the cores were well protected. The author believes that the above method can effectively solve the problem of insufficient core recovery in broken formations， and can provide guarantee and reference for follow-up work and similar projects.

Abstract:In view of the problems with gas drainage， such as short main holes， poor hole-making， frequent accidents in a coal mine of Bijie， Guizhou， a technique of using cross-floor comb-like directional long boreholes to control gas was put forward. The drilling pattern， drilling horizons and branch hole drilling processes were optimized to ensure the hole depth of the main hole and the coal intersection rate of the branch holes. During the trial， the drilling depth of the main holes was more than 600m， with the coal intersection rate of the branch holes up to 60%. The drilling hole completion quality has been obviously improved with the maximum gas drainage concentration per single hole up to 78%， the maximum gas extraction net volume 2.33m³/min， and less construction costs. It provides a new approach to gas control in the mining area of the Bijie city.

Abstract:With the increase of exploration drilling works， the conflict between exploration drilling and conservancy deepens， such as pollution of topsoil and vegetation due to long drilling periods of deep holes， improper disposal of drilling mud and cuttings， etc. On the deep drilling project of Guma Iron Mine in Luanzhou city， Hebei province， a series of green exploration technical measures， such as iron circulating tank， iron water tank， impervious cloth， bread brick hardened ground， were taken before and during drilling operations， so as to ensure that the drilling site is not polluted and the original appearance is reinstated after drilling. The experience can be used for reference for green drilling of deep core holes in the future.

Abstract:In the mineral exploration around the villages and towns， residential houses， farmland， roads， agricultural infrastructure， mountain vegetation and so on are usually encountered. In order to protect the ecological environment and meet the requirements of green exploration， in the detailed investigation of Xujiaqiao Black Talc Mine in Guangfeng， exploration was carried out by using technical equipment such as UAV aerial survey， portable full hydraulic core drills. With advanced equipment selection， environment-friendly technology， the proper exploration plan and specific environmental protection measures， the project has achieved the results of shortening the exploration period， improving core recovery， eliminating the typical exploration risk， reducing the labor intensity and cost of land requisition and relocation， and reducing the pollution and damage to the ecological environment； thus， realizing quality and efficient geological exploration with both good economic and social benefits， and achieving the goal and task of green exploration. Exploration of geology and mineral resources in the manner of green exploration not only protects the ecological environment of water and mountains， but also improves exploration efficiency and quality， reduces labor intensity and cost， and achieves the goal of energy saving and consumption reduction by use of high-standard green exploration technical means and environmental protection requirements. Green exploration is a sustainable and high-quality development road.

Abstract:In mine exploration， traditional core drilling has problems such as long drilling period and high cost， while air reverse circulation drilling has high drilling efficiency and low cost. In this paper， the fluid structure of the drill bit and the packing sleeve for air reverse circulation drilling has been improved and applied to mine exploration. Compared with traditional core drilling， air reverse circulation drilling has increased drilling efficiency by 70%~90% with costs reduced by 30%~50%， the drilling accident rate reduced by 60%~70%， no mud pollution in the drilling process， and less dust， meeting the requirements of green exploration.

Abstract:The large-diameter shale gas geological survey well （Well Chuanmudi-2） is located in the core of the Jianquan-Longhua synclinorium of the Wuzhishan-Tiangongtang structural belt in Southwestern Sichuan Basin with the design depth of 2500 m and the completion depth 2406.00 m. The drilling purpose is to explore continental shale gas in Xujiahe Formation and conventional gas in Leikoupo Formation. This paper introduces the drilling operations of Well Chuanmudi-2， whereby the application research on high-efficiency speed compound drilling， complex formation drilling fluid and casing cementing technology were carried out for the collapse prone mudstone of Jurassic and the poor drillability sandstone of Triassic. Through the research， the difficulty of casing cementing in the collapse section was resolved， drilling efficiency was improved， a qualified well for formation gas bearing test was built， the physical data such as core， cuttings and other were obtained， the stratigraphic sequence of the well area were identified， and the oil and gas display of layer 37 of Triassic Xujiahe Formation and Leikoupo Formation were hit； thus， achieving the drilling purpose， discovering oil & gas， and laying the foundation for shale gas geological investigation and evaluation which has a great significance to consolidate the poverty alleviation achievements in Wumeng Mountain area.

Abstract:The heat transfer performance of cement is an important factor that affects the heat transfer capacity of the wellbore. This article mainly introduces the current main research methods of cement thermal conductivity， and some understandings obtained from the research， such as the relationship between the addition of high thermal conductivity materials， the cement microstructure and water content， and thermal conductivity. At the same time， it points out that the unification and expansion of the existing research methods and the systematization of research content need to be further strengthened and improved. Based on the analysis of the research experience on porous materials such as building thermal insulation cement and rock， it is proposed that the research on the thermal conductivity of cement not only needs to unify the experimental methods and promote the use of numerical simulation methods， but also consider the curing conditions， the dynamic changes of internal moisture and the influence of external thermal insulation materials， and other factors on cement thermal conductivity. The systematic and standardized research methods and content can effectively improve the accuracy， efficiency and comprehensiveness of the research， and significantly increase the understanding of the thermal conductivity of cement so as to provide a certain reference for subsequent research.

Abstract:The research was supported by the shale gas survey well project in the middle and lower reaches of the Yangtze River， where wireline core drilling technology was used， and the formation encountered were mostly water-sensitive mudstone formations with high shale content， and dense formation with frequent soft and hard interbeds. In order to solve the problems of that bit balling of diamond drill bits and teeth breaking of PDC bits in soft and hard interlayers， which seriously affects the drilling speed and life of the drill bit， the article systematically analyzes the causes of diamond bit balling and PDC teeth breaking from the aspects of the bit structure and drilling fluid performance with respect to the field application results. It is noted that the above-mentioned problems arising from the field use of the drill bit are closely related to the design of the bit lip surface structure， the design of the bit waterway， the bit material and its surface condition，the drilling parameters and the performance of the drilling fluid. With examination of the drilling process and lithology， the structure was optimized and the design was improved of the existing drill bit， and the drilling parameters were also optimized. The results showed that the field drilling speed has been significantly increased， greatly improving the drilling efficiency over the mudstone section and the interlayer.

Abstract:With the low formation fracturing pressure and presence of a large number of natural fractures in the Haituo block， pervious circulation loss and lost return are very easy to occur during drilling， resulting in wellbore instability. In view of serious leakage in the Haituo block， a plugging-while-drilling fiber YTZ was prepared. At the same time， the composite plant fiber Xa and the fast plugging agent KF， which are well compatible with the base slurry， were selected to improve the ability of drilling fluid to stabilize the wellbore. Through the combination of the three plugging materials， a plugging system， and proper and effective drilling technology for the Haituo block have been formed， which effectively solved various well leakage problems in Haituo block， ensured the smooth drilling and completion progress， and reduced the economic losses caused by leakage. The plugging system showed good plugging effect through field application， and is worthy of further popularization and application in the Haituo block.

Abstract:Extraction of high-quality geothermal water with geothermal wells is a prerequisite for the extraction-reinjection geothermal heating system， and it is the most sensitive factor affecting the economic benefits of the entire hydrothermal geothermal energy project. The key drilling technology is of great significance to the well completion quality， and plays a decisive role in the development of the geothermal industry of Hancheng. In view of the geological characteristics of geothermal resources in the Hancheng area and the difficulties encountered in the development process， theoretical analysis and experimental research was conducted to investigate the key technical issues in geothermal drilling in the Hancheng with the five key technical aspects presented of local geothermal drilling heating extraction in Hancheng： anti-collapse and high-efficiency drilling， geothermal well sealing， acidization stimulation for productivity and reinjection improvement， in-situ extraction and reinjection optimization layout， cascade heat exchange and recharge. Through theoretical analysis of the technical problems encountered in the production process， the key technologies to solve the problems are proposed， and the five key aspects are explained in detail. They are of important scientific and engineering significance to the development and utilization of mid-deep geothermal resources in the Hancheng area， and can provide reference to other regions.

Abstract:SY-1 geo-thermal mineral water well in Yingshan， Sichuan Province is a key exploration well for geothermal resources with actual drilling depth of 2758m. It was found that the lithology of the thermal reservoir of Xujiahe Formation in Upper Triassic is mainly feldspar sandstone and siltstone， with buried depth of 2220 to 2758m and thickness of 538m. The Xiashaximiao formation consists of gray-green shale and dark purplish red silty mudstone mixed with yellowish brown medium-thick layered siltstone and massive fine-grained feldspar sandstone， which contains a mixture of high-pressure gas and brine， where complex drilling problems such as well collapse， well kick， overflow， lost circulation and wellbore contraction were encountered. Lab research was carried out on control of rheology， anti-sloughing and stability of high-density anti-sloughing drilling fluids， and with premium sodium bentonite as drilling fluid base， the coating agent， the fluid loss reducer （salt-resistant）， the anti-sloughing agent， and other materials were selected to obtain the final formula of high-density anti-sloughing drilling fluid： water+4% bentonite+0.1% soda+0.1% sodium hydroxide+1% to 2% tackifier HN-1+0.2% to 0.5% environment-friendly macromolecular coating agent+1% to 3% environment-friendly filtrate reducer HJ-1+1%~3% salt-resistant filtrate reducer HLY+1% to 2% environment-friendly anti-collapse agent HFJ+barite. The formula has adjustable density of 1.50 to 1.80g/cm³， infiltration loss of 4.0ml， good rheological property， and remarkable anti-collapse effect； and has been successfully applied in the field and ensured the smooth implementation of the project.

Abstract:With the continuous development of exploration and development in the Xihu area， the number of jack-up drilling platforms in the East China Sea is also increasing. Due to the influence of typhoon and multiple operations in the same location， the jack-up drilling platform will inevitably repeat the operation near their previous position， and cause the pile shoe slide phenomenon； thus leading to the decrease of cantilever operation range when in place， and failure to meet the needs of drilling operation. In the worse case， it may even affect the structural safety of the platform， resulting in engineering accidents with high operation risk. Taking the pile shoe of H9 jack-up drilling platform as an example， this paper analyzes the mechanical characteristics of the pile shoe under partial coincidence conditions， studies the failure mode of seabed soil， and puts forward horizontal force calculation models of the pile shoe in different types of soil. The finite differential method of the slide line is used to calculate the ultimate bearing capacity of the pile shoe. This paper analyzes the measures taken during H9 platform repeat placement， with a series of safety control measures put forward according to the requirements of offshore operation， which can provide a reference for safe and efficient jack-up rig repeat placement.

Abstract:The development of industrial economy brings convenience and material enjoyment to people’s life， but it also inevitably brings some environmental problems， such as pollution of soil， water and air； hence， harm to people’s life and survival. In order to sample and measure the pollution degree of soil and provide scientific basis for later treatment， ESD-70 environmental protection sampling drill is developed to integrate sampling and treatment. The rig is designed with the hydraulic cylinder for feed and lift， which is more stable than the traditional chain； It can drill at multiple angles， and equipped with the open and close control cabinet， and wireless remote control and electro-hydraulic control. It is compact， rubber crawler-mounted and with strong impact force of the power head， which can meet the needs of soil sampling up to the depth of 0~30m. The drill operates on a direct push sampling way with a double-tube sampler， and the samples directly reach the inner tube to effectively maintain the original state of the soil. The drill can also be used for simple jet treatment of soil； thus achieving use for multiple purposes. Moreover， the drill has the advantages of simple operation， high safety， stable performance and high efficiency， which can greatly reduce the labor intensity of soil sampling personnel.

Abstract:The Kriging method， which is an efficient and accurate metamodel， is widely used in slope reliability analysis. However， traditional methods couple the Kriging model directly with the Monte Carlo simulation method for reliability analysis， which leads to excessive memory usage or even overflow in high-dimensional slope reliability calculation with small failure probability， hence failure to find the solution. To this end， this paper proposes a Subset simulation method based on the Kriging metamodel to efficiently solve the problem of small probability slope reliability analysis. A single-layer cohesive soil slope and a practical soil slope are used to verify the effectiveness of the proposed method， and different regression models and related function models as well as the number of training samples are explored for the accuracy of the method. The results show that： （1）The proposed Subset simulation method based on the Kriging metamodel can effectively calculate the failure probability of slopes， and is more efficient than the traditional method； （2）During the construction of the Kriging model， the calculation accuracy of the model can be achieved when the number of training samples reaches10 times that of random variables. In addition， the number of additional training samples has little effect on the calculation results.

Abstract:Rotary drilling technology has the advantages of low cost， high drilling rate and environmental protection， and is widely used in pile foundation engineering. However， conventional rotary drilling is very slow in drilling hard rock （compressive strength greater than 80 MPa）. In order to solve the slow advance problem with rotary drilling in hard rock， and in view of high penetration rate of the DTH hammer in drilling hard and brittle rock， the combination of the DTH hammer with rotary drilling rig was explored. This paper introduces the construction process of the combined DTH hammer and rotary drilling technology with respect to the construction of anti-slide piles in the Guanjing Base landslide treatment project， analyzes the rock breaking mechanism， and verifies the feasibility of the combined DTH hammer and rotary drilling technology. It can provide a useful reference for the construction of hard rock pile foundation projects.

Abstract:During the process of grouting for seepage treatment of dam foundation overburden under some water head when retaining water， problems such as slurry dispersing， incomplete curtain， large consumption of cement， may be encountered. In reference to field practice， this paper investigates the use of the anti-washout slurry and the paste-like slurry， the injection-after-sealing principle， and grouting in tiers of different types of slurry for the upstream and downstream to solve the technical problems related to grouting of the overburden anti-seepage curtain and control of grouting under pressurized flow water. The technology produced good field results and can provide important reference for similar seepage treatment.

Abstract:-