Abstract:Geothermal energy is the only base load power among the major renewable energy sources. Hot dry rock （HDR） is a high temperature rock mass buried in the deep earth without connate water or with a little water， which can form an enhanced geothermal system reservoir through hydraulic stimulation， and a considerable amount of geothermal energy can be extracted. There are two main technological challenges associated with the development of HDR geothermal resource， i.e.， very hard rock， such as granite or basalt limits the rate of penetration （ROP）， and the temperature of the drilling system exceeds the operational limits of electronic tools like measurement while drilling （MWD） and steerable rotary tools. In recent years， the Utah FORGE project funded by the U.S. Department of Energy （DOE） provided an opportunity to test new drill bit technology and optimize drilling procedures to deliver a step change in ROP performance and drilling cost reduction. In this paper， the deployment of geothermal drilling technology R&D in the recent development plan of DOE Geothermal Technology Office is reviewed， the application of the redesign workflows based on physical limits in the drilling practice of the Utah project is selective analyzed， and the main areas covered by the multiple plans and projects funded by DOE in terms of geothermal drilling technology as well as the lessons learned from the Utah project in exploring and practicing drilling operation optimization are summarized.

Abstract:With the increasing dependence on foreign oil and gas， unconventional oil and gas energy such as tight oil and gas and shale oil and gas have become the focus of China’s energy development. Well factory fracturing technology is widely used in unconventional oil and gas development because it can reconstruct low-permeability formations， significantly reduce construction costs， shorten construction time， improve equipment and land utilization. Based on the discussion of the development status of well factory fracturing technology， this paper introduces the well pattern deployment characteristics of cluster horizontal wells， such as wellbore direction， length of horizontal sections， wellbore spacing and further statistically analyzes the key technical parameters of horizontal wells in segmented clusters， such as fracture length， cluster spacing and perforating cluster number. Moreover， the fracturing methods commonly used in cluster horizontal well factory fracturing are also introduced， including dual-wells simultaneous fracturing， dual-well zipper fracturing and multi-well combination fracturing， and the advantages and disadvantages of the common fracturing methods are analyzed by contrast. It is suggested that the theories such as prediction of interwell fracture interference and well cluster fracturing perforation cluster design should be developed. The research points out the direction for the development of well fracturing technologies for unconventional oil and gas reservoir in China.

Abstract:Given the critical importance of water cycle variations in extreme ecological environments such as high-altitude and arid regions to national ecological security， there is a pressing need to research on monitoring devices and technologies for key parameters of water cycle. This paper focuses on technical challenges associated with field in-situ/mobile/non-contact， automatic and stable monitoring of key parameters encompassing water cycle. A series of studies have been conducted to explore new technological devices for monitoring these key parameters of soil， air， ice， and snow in ecological systems. By establishing an integrated monitoring system for ecosystems based on the Internet of Things （IoT）， the industry technological barriers are hope to be broken through， and the interdisciplinary collaboration across fields including engineering， geology， and computer science can be fostered. Through collaborative efforts in researching and innovating key parameter monitoring technologies for the water cycle in extreme ecological environments， extensive， all-weather and three-dimensional monitoring of critical ecological functional areas will be achieved. This endeavor will hold significant importance in advancing China’s ecological civilization construction and promoting the comprehensive application and development of ecological monitoring technologies in the country.

Abstract:Direct push drilling technology has the advantages of no flushing medium， fast speed， small disturbance， etc.， but it is susceptible to the interference of factors such as large differences in the engineering properties of the soil at the site of organic contamination， resulting in tilting of the borehole and other phenomena. Organic pollutants will change the microstructure of the soil， resulting in changes in soil engineering properties， which in turn reduces the accuracy of direct drilling sampling points. Typical organic pollutants toluene and perchloroethylene were selected， and soil samples with different pollutant concentrations （toluene： 75， 120 and 672 mg/kg； perchloroethylene： 11， 53 and 183 mg/kg） were prepared to simulate the drilling encountered with the organically contaminated stratum. XRD， SEM， contact angle and nitrogen adsorption and desorption tests were carried out to investigate the changing rules of microstructure of the soil samples under the influence of different organic pollutant concentrations.The results of the SEM image analysis and nitrogen adsorption and desorption tests showed that： toluene and perchloroethylene encapsulated and chemically damaged soil samples， resulting in the agglomeration of soil particles， the reduction of the specific surface area， the obvious increase in the number of small pores， and the decrease in the pore volume of soil； the content of clay particles was 30.28% at the highest level. The highest clay content of 30.28% in soil sample 2# after 672mg/kg toluene and 183mg/kg tetrachloroethylene contamination， the specific surface area decreased by 30.70% and 33.40%， respectively， and the Pearson''s correlation coefficient of r=0.382 indicates that there is a certain positive correlation between the content of clay particles and the rate of reduction of the specific surface area. Meanwhile， due to the wrapping effect of non-polar molecules toluene and perchloroethylene on the soil particles， the hydrophilic groups of the soil samples were isolated， resulting in the deterioration of the hydrophilicity of the soil samples and the increase of the contact angle. This study suggests that organic pollutants can lead to changes in the microscopic characteristics of the soil， which ultimately leads to an increase in the non-homogeneity of the organically contaminated strata， which in turn can have an impact on the direct push drilling trajectory.

Abstract:Taking a shield tunneling project section in Xiaoshui as a case study， research was conducted to solve the key problem of the proportioning of grouting materials under karst geological conditions. A series of pre-tests were carried out in the pre-test period using raw materials such as clay， sand， gravel and cement， on the basis of which orthogonal tests on the factors of paste slurry proportioning were carried out by means of in situ soil extraction. The test results show that the dry clay and water-cement ratio are the factors that have the greatest influence on the compressive strength of the paste； The main influencing factor of the slump of the paste is the water-cement ratio， and the mixing amount of dry clay and sand contributes to the slump quite a lot； In terms of the compressive strength， the degree of contribution is in the order of the water-cement ratio>dry clay>sand. Considering the performance parameters and economy of paste slurry， it is recommended to choose No.6 （A2B1C3） paste slurry as the filling grouting material for this construction. The results of the study show that the preparation of paste slurry using clay and mechanism sand from the construction site can meet the requirements of the Design Institute for the performance index of karst filling materials.

Abstract:The rainfall conditions in the shallow hilly red layer area of Gongjue County in eastern Tibet are limited， and the occurrence and development of debris flows are mainly controlled by material source conditions and channel conditions， belonging to the “material source control type” of debris flows. Through geological investigation and statistical analysis， the conditions， mechanisms， and activity characteristics of debris flow formation were analyzed in detail. The following conclusion has been drawn： Gullies with a drainage area less than 1.0km² and a longitudinal gradient of 100‰ to 300‰ are prone to debris flows； Due to the influence of structure， freeze-thaw weathering， and gypsum containing rocks， the sources of debris flows are relatively abundant， with slope erosion as the main type of source and a distribution characteristic of “multiple points and wide areas”. The supply form is characterized by “zero storage and whole extraction”； Controlled by the form of material supply， the formation of debris flows mainly includes three stages： slope erosion initiation， gully bed accumulation， and bottom erosion； Due to the influence of material sources， the fluid properties of debris flows in the area are mainly viscous transitional， and debris flows have the characteristics of multiple periods， medium to high frequencies， and smaller scale of single debris flows.

Abstract:In order to comprehensively develop the geological disaster prevention and control technology system of “civil air defense+technical defense”， and build a geological disaster monitoring and early warning system based on universal monitoring instruments， this paper takes the Dayuanzi landslide in Baoshan City， Yunnan-Guizhou Plateau as an example， introduces the various links of the geological disaster landslide from scheme design to monitoring data screening and mode model design in detail， and the application of three parameters model in the monitoring and early warning system namely rainfall， displacement deformation and crack are expouneded. Through collecting key information of the geological disaster body， such as rainfall， displacement deformation and crack change， the monitoring and early warning model is optimizd， the threshold is adjusted， and the change information of the geological disaster body is captured in time. Moreover， the key link of building a universal monitoring and early warning system is completed relying on the self triggered early warning of the platform criterion model， thereby， the effect of universal monitoring and early warning is achieved and greatly improved the automation and intelligence of the geological disaster prevention system.

Abstract:The exposed karst areas has the characteristics of strong karst development and complex hydrogeological conditions， which leads to the concealed nature of the channels in underground river systems and the challenges for pollution prevention. Taking pollution prevention project in Pingqiao Underground River System as an example， the measure of “underground impermeable curtain + sewage pumping and drainage” was used in the main flow channels near the pollution source to realize “near source drainage truncation”.The construction faced difficulties such as blockages and low drilling efficiency due to complex karst fragmentation and excessive waste of materials due to long grout flow distances in strong karst segments. Effective technical measures such as suitable drilling techniques， pure pressure grouting， cement mortar grouting to fill dissolution voids， low-pressure and limitated volume grouting and accelerated slurry grouting were employed to ensure the quality of the project， which achieved the goal of contaminated groundwater treatment from the source. The technology of “near source drainage truncation” provides a replicable geoscientific management model for contaminated groundwater prevention in analogous hydrogeological conditions.

Abstract:Laser drilling uses gas as circulating medium to clean holes， and the reasonable gas flow properties are the guarantee for hole cleaning efficiency. Gas nozzle is the direct factor affecting gas flow properties， and its unreasonable structural design seriously affects the efficiency of laser drilling. Aiming at the gas nozzle in the laser drilling experimental platform， the basic type of the nozzle is constructed， the nozzle structure size that affects the gas hole cleaning efficiency is analyzed， and the simulation scheme is formulated. Moreover， the gas flow field is simulated by Fluent， and the hole cleaning effect is analyzed. The nozzle structure and simulation results are analyzed by neural network， and the neural network model is trained to get and verify the best nozzle structure parameters for hole cleaning efficiency， which provides reference for the nozzle structure design.

Abstract:Drilling cuttings are a type of solid waste generated in drilling engineering， usually treated with cement for solidification. However， the production process of cement is accompanied by a large amount of carbon dioxide emissions， which not only increases greenhouse gas emissions but also has adverse effects on environmental protection. In response to the above situation， this article proposes a new method of microbial induced magnesium carbonate precipitation and solidification of drilling cuttings. The study on the mechanical properties of microbial induced magnesium carbonate precipitation solidified drilling cuttings shows that the strength of the solidified body decreases with the increase of water content and urea concentration， and increases with the increase of active magnesium oxide concentration and curing time. The minimum strength is 0.21MPa and the maximum strength is 3.5MPa， fully demonstrating the importance of selecting the most suitable ratio. The characterization results of FTIR， XRD， and SEM showed that the microbial induced precipitation products of magnesium carbonate were rose shaped magnesite （4MgCO₃?Mg（OH）₂?4H₂O） and needle shaped magnesite （MgCO₃?3H₂O）； The product uses a dense carbonate network structure to bond loose particles into a structurally intact solidified body， thereby elucidating the mechanism of microbial induced magnesium carbonate precipitation and solidification of drilling cuttings.

Abstract:Natural materials have become an important direction for the research and development of environmentally friendly drilling fluid treatment agents due to their advantages of easy degradation， environmental friendliness， rich sources， and low prices. Based on natural pomelo peel， amide and sulfonic acid groups were introduced through chemical synthesis to form a modified pomelo peel fluid loss reducer that can meet the requirements of green， safe， and efficient drilling in high-temperature strata， and its temperature resistance， inhibition， and salt and calcium resistance performances were evaluated. Pomelo peels are rich in active ingredients such as plant phenols and polysaccharides. The modified pomelo peels have strong temperature resistance and a filter loss reduction rate exceeding 70% at 150℃. The rolling recovery experiment results show that at a dosage of 0.3%， its inhibitory effect is better than KCl. The anti-pollution experiment shows that the modified pomelo peel fluid loss additive has good salt and calcium resistance. At a dosage of 0.3%， it can keep the filter loss below 10 mL in fresh water base mud， salt water base mud， and saturated salt water base mud. When the CaCl₂ content is 3%， the filter loss reduction rate reaches 82.22%. The modified pomelo peels have significant fluid loss reduction properties， providing new technical ideas for the development of environmentally friendly drilling fluid treatment agents.

Abstract:Hot dry rock （HDR） is a clean and renewable energy resource developed mainly through enhanced geothermal systems （EGS）. In EGS engineering， geothermal drilling technology is required for the construction of both injection wells and production wells， and the formation fracture and wellbore collapse during high temperature and high pressure drilling are important problems in hot dry rock drilling construction. Under the action of temperature difference， the temperature stress is generated between mineral particles due to the difference of thermal expansion and cold shrinkage characteristics of mineral particles of rock， which results in thermal fracture of rock mass. In this paper， with the help of RFPA numerical simulation software， the fracture propagation of granite in wellbore under the action of cold shock during hot dry rock mining is studied. The results show that during the cold shock process of the wellbore model， as the increase of the cold shock time， the tensile stress on the rock surface first increases to a peak value and then decreases slowly. The fracture growth can be roughly divided into early， middle and late stages. In the early stage， an annular tensile stress zone appears around the wellbore and uniform micro-cracks begin to appear. In the middle stage， with the increase of time， the tensile stress zone gradually spreads to the periphery of the wellbore and the fracture spreads outward beyond the tensile stress zone. In the late stage， the tensile stress gradually decreases to less than the tensile strength of the model， and the fracture propagation slows down until it stops. The confining pressure， well diameter and temperature have a significant impact on the damage effect of the surrounding rock under cold shock. Among them， the temperature and well diameter promotes the growth of cold shock fracture while the confining pressure inhibits it.

Abstract:In present， the measured location of the near-horizontal directional drlling trajectory is lag behind the bit， and the actural parameters of the delayed area can not be obtained in time， thus artificial prediction should be made for the next trajectory adjustion. In order to decreased the human facts and improve the accuracy of the prediction， a forecasting model is established based on BP neural network which is used for controlling underground directional drilling trajectory in tunnel. The model is a four-layer BP neural network， and it chooses 11 input parameters and 2 output parameters which are changed from 13 borehole space and trajectory controlling parameters from 12m before MWD including dip angles and azimuths etc. The parameters of the net forecasting model is obtained using 502 groups of training data from 6 boreholes in different mining areas. Then the forecasting results of the 12 groups of test data are compared with that of the artificial experience from 24 technicians. The results show that the mean absolute error of the downhole space parameters i.e. dip angle and azimuth are only 0.51° and 0.68° predicted inrespectively by the logsig activation function and the double-hidden-layer BP neural network which has the point structure of 9×6， and the prediction error obeys normal distribution. The accuracy prediction results derived from the BP neural network model is 35% lower than that from the technicians who work more than 5 years， and the effect from the field application is satisfied which meets the needs of drilling trajectory control. The research offers theoratical and practical base for the intelligent directional drilling work.

Abstract:PDC bits are widely used in oil and gas drilling and geological exploration drilling. and good technical and economical results have been obtained. However，abnormal wear of the cutting element in drilling engineering affects the improving of technical and economic effectiveness of the advanced drilling method. Company Smith drill bit of Russia （Smith Bits） has developed a new cutting element， rotating around its inner shaft，inhibiting the wear of PDC cutting element. It is a new innovation and has practical significance. Prof Neskoromnyh V. V. et al have analyzed and researched on design and characteristic parameters of the bit with ONYX. Finished tests show， that the wear resistance of the ONYX is better than， that of the fixed PDC element. The result of drilling using such bit are better and the bits are being used actively in geological and prospecting organizations of Russia. It is worth for us to pay attention to.

Abstract:In order to resolve the puzzle that the scaling on the inner wall of the drill pipe seriously restricts the safe， high-quality， and efficient implementation of wire-line core drilling， the comprehensive study was conducted on the scaling mechanism and influencing factors of diamond wire-line core drilling on the inner wall of the drill pipe. The results indicate that： When the structure of the drilling tool and the performance of the drilling fluid are constant， the solid content and particle size in the drilling fluid are the main factors affecting the scaling of the inner wall of the drill pipe. The particle size of rock cuttings produced by diamond core drilling ranges from 5 to 100μm， it is generally small and difficult to remove by the natural settlement. For the reason， the TGLW series small centrifuge is developed. Field tests have shown that the centrifuge can increase the peak value of solid particles in drilling fluid from 5~80μm to 3~10μm， the median particle size of the solid phase ranges from 11.189μm to 3.513μm， the solid phase clearance rate reaches over 90%， and the solid phase content of the drilling fluid is controlled below 0.5%， which not only maintains the performance of the drilling fluid but also prevents scaling on the inner wall of the wire-line drill rod.

Abstract:In order to improve the performance of the wire-line core drill pipe， the stress， structural characteristics and traditional treatment technology of the straight-connected wire-line core drill pipe were analyzed， and a zonal heat treatment process was proposed. Through the heat treatment of both ends， the heat treatment performance of the middle pipe body area and the thread area at both ends was different， and the comprehensive strength of both ends was improved while the stress state of the thread part was improved. It can make the drill pipe string have both high strength and flexibility， and greatly improve the mechanical properties and wear resistance of the drill pipe. The quenching and tempering hardness HRC33~38 can increase the strength by 37.7%， the hardness by 40% and the impact resistance by 46.7% under the condition that the elongation of the pipe body is basically the same as that of normalizing and tempering. When the quenching and tempering hardness is HRC38~42， the wear resistance of the material is increased by 9.1%. It is more suitable for full hydraulic drilling rig construction and deep hole drilling， and provides the optimal scheme for drilling rig and drill pipe matching.

Abstract:Oil and gas well leakage is a common problem in drilling， usually sealed with cement. However， the heavy weight of ordinary cement can easily lead to failure in plugging. Meanwhile， low-density cement has been rapidly promoted in plugging. The compatibility between low-density cement and retarders is particularly important， which the performance of cement is effected seriously by retarders. In response to the above issues， a retarder for low-density cement. The infrared and thermogravimetric results indicated that the preparation of the retarder has achieved ideal results， with a temperature resistance of 450℃. The test results of the high-temperature and high-pressure thickener showed that a retarding time of 225 minutes was obtained for the low-density cement with 0.4% retarder under the conditions of 120℃ and 68MPa， which is a good retarding effect. By using a six speed viscometer， thickener， and unconfined compression tester， the effect of retarders on the conventional performance of low-density cement slurry was studied. The experimental results confirmed that different concentrations of retarders did not have a significant impact on the rheological properties and compressive strength of cement， and an increase in temperature would shorten the thickening time of cement slurry. The prepared retarder has been applied on site together with low-density cement， and the on-site results have shown that the retarder has excellent effects and meets the needs of on-site construction， which is worthy of further promotion.

Abstract:In order to study the shallow geothermal energy contained in the Ordovician limestone of Jingxing County， a thermal response test well in the valley is drilled， where the physical mechanics， thermal properties and geothermal field characteristics of the rock and soil mass are tested. As a result， the average geothermal temperature below 10m reached 16.77℃， and the heat transfer per unit length in summer and winter under the test conditions were 68.38W/m and 65.78W/m， respectively. Eight indicators such as the burial depth of the groundwater level and the velocity of the groundwater were selected to evaluate the suitability of ground source heat pump with buried pipe in Jingxing County， and the evaluation area was divided into more suitable area， suitable area and unsuitable area. Among them， the more suitable area is 244.12km²， accounting for 16.82% of the total area. On this basis， the resource potential evaluation was carried out on the more suitable area， and the resource potential and energy saving and emission reduction capacity were calculated. In order to better verify the development and utilization value of the shallow geothermal energy contained in the Ordovician limestone of Jingxing County， the relevant supporting application engineering and monitoring equipment were installed to monitor the energy consumption under different test conditions. Compared with the energy consumption of the ordinary household air conditioners， the annual operating cost of ground-source heat pump with buried pipe is about 55% of the air conditioning， which possess the development and utilization value.

Abstract:In the process of drilling engineering construction， the mechanical failure will inevitably appear. The fault tree is one of the common methods to analyze the causes. But in the construction， due to the insufficient data or no attention to save these data， assigning value is difficult in the actual application and only qualitative analysis can be made. In view of the fuzziness and uncertainty when faults of the engineering construction machinery happened， the occurrence probability of the bottom event is described with fuzzy number， and a machinery fault tree analysis method for engineering construction based on triangular fuzzy number is proposed. This method uses the experience of experts， field technicians and operators to describe the probability interval of each bottom event. The median importance of the triangular fuzzy number is caculated and is used to sort the causes of the fault， which is served as the basis for formulating preventive measures. Finally， it is applied to the reason analysis of mix-material blocking pipe of long spiral drill， and makes targeted preventive measures for faults according to the fuzzy importance. The results show that the ranking of important influencing factors is consistent with the qualitative analysis and judgment of the field technicians and operators.

Abstract:In recent years， the main ore belt of Xitieshan has gradually entered deep exploration， mainly relying on tunnel drilling to determine the distribution and reserves of deep mineral deposits in the mine. During the implementation of tunnel drilling， challenges such as airport chamber support， drilling of fractured strata， core extraction of water sensitive strata wall protection， and treatment of water inrush strata are faced. If not handled properly， it can cause airport chambers to fall and collapse， and drilling accidents such as jamming， burying， and collapse may occur. In severe cases， drilling may be scrapped， which restricts the exploration process. In response to the technical difficulties in drilling complex formations mentioned above， research has been carried out on strengthening tunnel support， selecting reasonable drilling parameters， optimizing drilling structures， formulating complex formation flushing fluid formulas， and using rapid setting cement for sealing. This has ensured the construction safety of the tunnel airport， effectively solved the drilling difficulties in various complex formations in the area， reduced the incidence of accidents and drilling scrap rates， improved drilling efficiency and quality， and provided reference for subsequent drilling construction in similar formations.

Abstract:In recent years， as the most important means to access into the earth， drilling is facing the problems that the formation is becoming more and more complex， and the probability of drilling collapse， falling blocks， diameter reduction and over-diameter accidents is increasing， which seriously restricts the improvement of the quality and efficiency of drilling engineering. Wall protection and plugging material is an indispensable key engineering material for drilling engineering and the wall protection and plugging technology is an important technical link to ensure safe， fast and continuous drilling work and is the main content of drilling treatment in complex formations. From the perspective of science popularization， this paper introduces the basic concept and composition of wall blocking materials， the wall blocking effect of flushing fluid and cement-based materials and the further development space of wall blocking materials， so as to deepen the understanding of wall blocking materials and promote its R&D and application.