Abstract:A series of fluid flow tests on different concentrations and different types of salt solutions were conducted on the shale samples through the pressure transfer experiment device to study the influence mechanism of salt ions with different water activities on shale seepage. The experimental results show that the salt solution with the strongest ability to block the pore pressure transmission of Xiushan Shale in Longmaxi Formation is HCOONa among the same concentration of different brines. In addition， the five types and concentrations of salt solutions with better resistance to pore pressure transmission are 20% HCOONa， 5% HCOONa， 20% KCl， 20% HCOOK and 5% NaCl. The highest concentration does not always have the best ability to block shale pore fluid transfer for the same type of salt solution. When the mineral composition is almost the same， the time to penetrate the pores and average permeability of the Xiushan shale of the Longmaxi Formation is 90.11% higher and 99.14% lower than that of the artificially compressed shale. The seepage law of artificially suppressed shale with salt solution is consistent with the real shale. However， the difference between the characterization coefficient is more than 90% for the actual permeability and seepage time. Moreover， a unit distance seepage time model based on water activity and water activity-permeability formulas under different salt ions are proposed for the Xiushan shale of Longmaxi Formation. The research results can provide experimental and theoretical basis for maintaining shale wellbore stability of the Longmaxi Formation with brine drilling fluid.

Abstract:The traditional geothermal well structure is not suitable for carbon dioxide blasting technology to build hot dry rock reservoir； Thus， this paper further explores a new well structure and related technology suitable for carbon dioxide blasting technology. With regard to the actual drilling conditions in the horizontal well section （blasting hole） of the new well structure， rock mechanics experiments and thermal-fluid-solid three-field coupling numerical simulation were conducted to study the variation law of physical and mechanical properties and reservoir temperature distribution characteristics of hot dry rock reservoirs near horizontal well sections （blasting hole） after drilling. The results show that the thermal stress produced by cooling of drilling fluid is the main cause for the change of reservoir rock properties and occurrence of the thermal damage zone. The regional temperature distribution exhibits the characteristics of “rapid cooling zone-steady cooling zone-uncooling zone” in reservoir near the borehole during cooling. The initial reservoir temperature and the cooling time have major influence on temperature distribution in the rapid cooling zone and on the thermal damage zone. This study can provide more accurate theoretical guidance for carbon dioxide blasting fractured hot dry rock reservoir.

Abstract:Hydrate reservoirs have the characteristics of weak consolidation， high clay content and low permeability， which is prone to lead to serious problems of wellbore and reservoir instability, low gas production and sand production during drilling and production. Sand production is a bottleneck which restricts the safe and efficient exploitation of hydrate. The existing sand control technology of NGH reservoir mainly comes from the sand control methods commonly used in conventional petroleum exploitation， and the contradiction between sand control precision and permeability enhancement is prominent. This paper proposes a gas recovery method with ultrasonic atomization for sand control and water drainage for hydrate reservoirs， which can effectively block sand greater than 10 microns，and produce water in the form of mist with small droplets of about 5 microns， so as to realize continuous production of water and gas. Preliminary simulation experiments were carried out based on an experimental simulation evaluation device. Results show that the method is feasible and water mist can be produced continuously through the cone holes of the atomizing plate. However， the atomization device needs to be further optimized due to the presence of mud contents； otherwise the mud contents will seriously affect atomization. The preliminary work can provide a new idea for sand control and gas recovery enhancement in hydrate reservoirs.

Abstract:Well D21 was drilled to explore the geothermal resources in the western slope zone of Rongcheng. The China Geological Survey deployed Well D21 in Rongcheng， Xiong’an New Area with the designed depth of 3000m， and the completion depth 3083.74m. This article introduces the drilling conditions， well structure， drilling operation， and pumping test process of Well D21， and summarizes the drilling results obtained. The hydrogeological parameters of the thermal reservoirs in the Cambrian and Jixian systems have been collected from the well， and they can be used for planning of geothermal development in the new area.

Abstract:ZK2 well is a geothermal well in Xiushan county of Chongqing city. It reached the design target formation of the Loushanguan Group at depth of 1674.28m， but the water yield did not meet the requirements. In order to increase the water yield to achieve the purpose of tourism development， new water-bearing target areas were investigated according to geological data and geological means， and a plan for directional drilling from 1674.28m was determined. With the MWD tool and the bent mud motor， the inclination and azimuth of the well were adjusted through the combination of sliding drilling and compound drilling with the well successfully drilled into the target area to increase water production and temperature.

Abstract:Impact sampling is an effective means to get high-quality， efficient， undisturbed and pollution-free sample from unconsolidated formation in eco-geological survey. However， the common portable impact sampling drill is driven by gasoline engine， which cannot somehow meet the development requirements of safe production and green exploration. Therefore， a portable electric impact sampling drill driven by lithium battery and its complete accessories were developed. The design and selection process of the electric hammer， the controller， the lithium battery power source of the drill is introduced in detail together with the matching sampler and the hydraulic puller driven by the same lithium battery. The sampling test of the drill has been carried out. Field results proved that the portable electric impact sampling rig and its complete accessories are portable and reliable， and can get high quality samples from unconsolidated formation within 5m safely and efficiently without carbon emissions， demonstrating a beneficial attempt to implement green exploration and promote the electric upgrading of shallow drilling equipment.

Abstract:In view of the current situation of core drill training in China， and with comprehensive analysis of the virtual reality visualization at home and abroad， a training system different from the existing one which is limited to the basic function training operation of the drill has been developed through combination of virtual reality technology， Unity3D and teaching AIDS. The platform is composed of the full size model， the programmable controller and the virtual scene. On one hand， the simulation training system software simulates the operation of the drill； on the other hand， the relevant data in the drilling process can be displayed to enable students to master drilling procedure parameters， and identification， prevention and treatment methods of complex accidents in the hole. After several virtual scene control experiments and tests， the platform can run stably， students can intuitively feel the operation of the controlled object， enhance the hands-on experience， deepen the understanding of geological core drilling， and reduce the teaching cost.

Abstract:Vibration isolation of the sonic power head of is the key to ensure whether it can work safely and stably. In this paper， the forced vibration model of the power head isolation mechanism is established based on the damped forced vibration theory of the single-degree-freedom system， and it is found that the rubber stiffness k， damping c and frequency w of the external excitation force are the main factors affecting the vibration isolation performance of the power head. On this basis， the dynamic model of the power head is established to simulate its vibration characteristics. The results show that the vibration isolation transfer rate of the power head is proportional to the frequency of the external excitation force， inversely proportional to the stiffness of the vibration isolation spring， and proportional to the damping of the vibration isolation spring. When the stiffness of the spring increases to a certain value， the vibration isolation transfer rate tends to a constant value. Therefore， in practice， the vibration isolation performance of the power head can be improved by appropriately increasing the external excitation frequency and choosing rubber material with low stiffness and large damping for the vibration isolation spring. The conclusions can provide reference for setting the working frequency of the sonic drill and optimizing the vibration isolation mechanism of the power head.

Abstract:With the advantages of high automation， wide drilling adaptability， good mobility and high drilling efficiency， truck-mounted hydraulic drilling rig is widely used in coal bed methane extraction wells， water wells and so on. As an important component of the drilling rig， the mast supports the power head for rotary drilling. The vibrational stability of the mast has very important influence on the reliability of the drilling rig. Through modal analysis， the natural frequency and the modal amplitude of the mast are determined， and the results show that the resonant phenomenon may occur. Through the topological optimization analysis of the mast and according to the actual functions of the mast， the optimal model is obtained. The static structural analysis and the modal analysis results show that the optimization effect is remarkable， which meets the structural strength requirements and avoids the occurrence of resonance. The finite element analysis of the mast provides theoretical support for the structure design of the mast， and provides a modern mechanical structure design method.

Abstract:This paper studies a new type of manipulator that can retain the freedom of rotation of the drill pipe in terms of its stability and safety in movement of the drill pipe. The manipulator improves the pressure-keeping retention effect through the accumulator during pump shut-off， and retains the rotational freedom of the drill pipe through the roller structure. In this paper， the multibody dynamic model of the manipulator and the supporting hydraulic control circuit are established， and the mechanic-hydraulic co-simulation is performed. Under the condition of changing the drill pipe diameter and the hydraulic circuit stress respectively， the clamping effect of the manipulator was observed. Through simulation， the clamping force change curve and the gravity position change curve of the drill pipe are obtained， the allowable pressure range of the hydraulic system is determined， and the movement smoothness of the drill pipe clamped with the single manipulator is verified to meet the requirements.

Abstract:Air lift reverse circulation drilling technology has been widely used in the field due to its high drilling efficiency， simple process， cleanliness of the hole. However， the design of the dual wall drill tool mainly relies on the experience， and immature theoretical research leads to the lack of in-depth analysis of the problems in the field. In this paper， the velocity and pressure characteristics of the flow fields in the dual-wall drill rod annulus and the air-water mixer in air-lift reverse circulation technology are simulated by means of the numerical simulation method. Flow field analysis results show that reducing diameter changes in the annulus or increase the length with the diameter change is more advantageous to reduce the pressure loss and energy loss along the dual-wall drill rod， and the completely symmetrical air inlet structure of the air-water mixer is more advantageous to the evenness of the up-hole velocity， and reduces the occurrence of blockage. The results of the study can and provide reference for design of gas lift reverse circulation drilling tools， and solutions to field problems.

Abstract:The technology of casing drilling is one of the effective methods to solve the problem of complex formation drilling. In view of the technical problems in the process of casing drilling， such as sticking in the annulus between the inner and outer tubes， complex load on the drilling string， high energy consumption， limited continuous running depth of casing， bit sticking in deep hole hot dry rock granite broken under the action of thermal stress， a continuous casing drilling mechanism with twin impregnated diamond bits is innovatively designed in this paper. Theoretical analysis shows that concentric rotary drilling with the twin bits produces small size cuttings to avoid sticking of both the inner and outer drilling strings， improve the stress state of the drilling tool and reduce the risk of breaking of the drilling tool. Compared with conventional casing drilling， the energy consumption of the inner bit is reduced by29.29%. The outer bit employs a high matrix with the staggered water port and reinforcement structure， which effectively avoids local circulation of drilling fluid and improves the continuous running depth of casing. The design of this mechanism provides a new idea for casing drilling technology.

Abstract:The Jiama 3000m Scientific Drilling Project in Tibet is the first 3000m scientific drilling project in the field of solid mineral investigation in the Qinghai-Tibet Plateau， and its purpose is to predict deep mineral resources directly， build a comprehensive exploration model with multiple information， and realize the demonstration of increasing reserves through the study of fine anatomy of orebody structures， hyperspectral analysis and mineral exploration indicators. This paper introduces the general drilling operations and key technologies in 3000m scientific deep drilling in Jiama， Tibet. With use of HXY-8VB type frequency conversion manual-automatic drilling rig， eccentric deviation correction drill bits， automatic vertical drilling tools， “drilling and reaming” drill bits， environmental protection flushing fluid systems and other technological measures， many technical difficulties， including selection of drilling equipment， deep hole trajectory control， complex formation coring， green exploration， have been solved. The project is completed at final hole depth of 3003.33m， creating the record in small-diameter solid ore exploration depth in the Qinghai-Tibet Plateau. It not only provides detailed physical data for the study of deep-hole mineral metallogenic theory and resource exploration in this area， but also provides technical reference for extra-deep hole drilling on the plateau.

Abstract:NLSD-1 hole of Nanling Scientific Drilling is located at the intersection of the Wuyi northeast structural belt and the Nanling east-west structural belt in southern Jiangxi. The rock bedding， foliation， structural fractures and cleavage are developed with frequent occurrence of soft and hard interbeds， fracture zones and multiple magmatic rock intrusions in the borehole. These geological factors cause serious natural bending of the borehole. In order to ensure the verticality of the borehole， wireline coring hydraulic hammer drilling and tower wireline core drilling were used to prevent borehole deviation. In case of strong deflecting formation where borehole deviation can not be controlled by borehole deviation prevention technology， directional drilling technology was used together with sidetracking for borehole deviation correction to achieve the purpose of artificial intervention of the borehole trajectory. Analysis and research show that the deviation prevention and correction technology has significant deviation prevention and straight keeping effect in deep hole drilling in complex and strong deflecting stratum.

Abstract:The formation in ZK1102 core drilling hole in the peripheral pre-survey area of Zhongba， Ningqiang county was fracture-developed， and the drilling leakage was serious. Due to insufficient pumping time， the drilling fluid had not reached the bottom of the hole when drilling began， resulting in a serious bit burning accident. The optimum accident treatment scheme was selected through scientific analysis and assessment based on the equipment characteristics of the portable full hydraulic drill and the formation conditions， at the prerequisite to guarantee the prospecting results， and the safety， economy and reliability of accident treatment. The BTW drill pipe was used to connect the hydraulic cutter for cutting the accident section in the drilling string， and then the NTW tool to connect the grinding mill to mill out the remaining drill bit； in such a way， the drilling accident was solved efficiently， economically and safely. With reference to field applications of the hydraulic cutter， the causes for cutting failure are analyzed and summarized under different operation sequences and cutting parameters， which has accumulated rich field experiences for on-site operators and laid a solid technical foundation for smooth handling of bit burning accidents. In this paper， the use of the hydraulic cutter to deal with core drilling bit burning accidents has been actively explored， which provides reference for other areas to use the hydraulic cutter to deal with similar complex drilling accidents.

Abstract:In water well drilling， the problems of hole collapse， falling stones， wellbore shrinkage and leakage are prone to happen due to poor stability of bedrock complexity，which seriously affect the quality and efficiency of well drilling. The expandable tubular is an effective measure to solve the wall protection problems in complex formation， but the conventional one is not suitable for water well drilling for its high cost and complex process. In view of this， research was carried out on packer-activated expandable tubulars. The packer is used as the expansion mechanism to make the thin-walled metal pipe expand in the target layer and stick to the well wall， so as to achieve the purposes of wall protection， plugging and casing repair. This paper introduces the development and operation of the expandable tubular system， and the field test of the technology for wall protection and casing repair， which is the first application of the technology in the field of water well drilling and completion.

Abstract:With the characteristics of loose structure， high water permeability， low cohesion and poor self-stability. sandy gravel formation often brings many problems to the field work. In order to better research the ground subsidence laws and corresponding control measures during trenchless pipe jacking in sandy gravel formation， this paper takes the pipe jacking section W31-W32 of the rainwater and sewage pipe network in the areas of Huayang， Wan’an and Zhengxing in Chengdu city as the research object， and puts forward the ground subsidence control measures suitable for sandy gravel formation by means of construction method comparison， numerical simulation and field measurement， The results show that in the sandy gravel formation， reinforcement of soil around the pipe by sleeve valve pipe grouting and reinforcement of the pile portal by high-pressure jet grouting are proper and effective with the ground subsidence after reinforcement reduced by 48.1% compared with that without reinforcement， and the surface subsidence at the portal reduced by 51.1%， meeting the requirements of ground subsidence control； which verifies the effectiveness of formation reinforcement measures. It can provide reference for subsequent similar pipe jacking in the future.

Abstract:In trenchless horizontal directional drilling in high-altitude areas， mud leakage in fracture-developed formation is one of the key problems that plagues trenchless works. It will not only affect the effective circulation of drilling fluid， but also form a large number of cuttings beds in the borehole. That will lead to other problems such as excessive wear of drilling tools， abnormal increase in frictional resistance， and reduction of the effective diameter. In view of the granite fractures in a Tibetan site， the close-range photogrammetry technology was used to quantitatively characterize the fractures， and found that the fracture width of the fractured strata in the study area was less than 4 mm. At the same time， basalt fiber is proposed as the main fracture plugging agent， and the formulation system of basalt fiber plugging-while-drilling has been established. The experimental results showed that the multi-grade combination of 3mm， 6mm and 9mm basalt fibers can achieve the best results， where the 3mm fiber can form a space skeleton structure with inert materials， and the 6mm and 9mm fibers can function as “reinforcing” with a certain strength. Results at the jobsite indicate that the solid phase content in the mud decreased by 13.14% with basalt fiber plugging， ensuring effective， green， and safe drilling for the long-distance mountain crossing with trenchless technology.

Abstract:The development and utilization of geothermal resources can play a positive role in reducing CO₂ emissions and restraining global climate change. Underground heat transfer of shallow geothermal energy mainly includes the groundwater well system and the underground buried pipe system. Their common advantages are high energy utilization coefficient， safety and stability， zero pollution discharge， etc.； however it has advantages and disadvantages in heat exchange efficiency， development and utilization conditions， space occupation and so on. This paper describes the suitability evaluation index of the shallow geothermal energy underground heat exchange system； and in the execution of the shallow geothermal energy demonstration project in Zhengzhou， field tests such as pumping and reinjection test， geotechnical thermophysical parameter test and formation thermal response test were carried out respectively， and the suitability of two heat exchange modes of shallow geothermal energy is analyzed and compared， It is concluded that the rock and soil in the construction area has high thermal conductivity and volume specific heat capacity， which is conducive to heat conduction and maintenance； but the buried depth of the regional water level is shallow， the reinjection capacity is only 107.37m³/d， and is poor. Through comparison， the underground buried pipe heat exchange system which is more suitable for the development and utilization of shallow geothermal energy in the construction area has been finally optimized and selected for development.

Abstract:The exploration of soil and groundwater in contaminated sites needs to meet the requirements of sampling and well construction at the same time. The hollow auger split-tube can provide some self-driving， which can drill groundwater monitoring wells while obtaining low-disturbance soil samples. This paper analyzes the technical characteristics of the hollow auger， and ，puts forward the direct push sampling and well construction technology with the hollow auger split tube based on the direct push environmental sampling equipment. Field tests were carried out in the quaternary sandy soil stratum with the relative density of sandy soil of 0.46~0.83（12~16m）， and the test results show that the hollow auger split-tube method can effectively solve the problem with the traditional direct-push sampling method by which it is difficult to reach the predetermined depth in the firm soil area； meanwhile the core recovery was higher than 90%. The technology is a kind of environmental sampling technology worthy of promotion.