Abstract:Through years of geothermal drilling engineering practice， it is throught that under the guidance of the traditional geothermal system theory of “heat source， channel，reservoir，overlying rock”， some problems exists such as high drilling risk and imperfect exploration results using hydrogeological survey and geophysical exploration methods to select geothermal resource target areas and drilling locations. The problem is more serious especially with the increase of exploration depth. In view of the above problems，combined with relevant literature and the practice of geothermal drilling engineering， this paper shows that there are huge high-temperature and high-pressure gases in earth interior and the formation of the geothermal， oil and gas， gas-bearing coal seams and other energy is closely related to the gases migration in the earth interior. The formation of geothermal resources is mainly caused by the action of carrying and driving （medium and power） of the deep gas and is enriched in a certain geological environment and space. On this basis， the model of reservoir-formation of hydrothermal geothermal resources is re-established， including three types of convective， conductive and compound type of convective-conductive. Moreover， on the basis of the traditional geothermal system theory， innovation of geothermal theory and the dynamics of the earth interior gases are further proposed to make the geothermal systerm theory more scientific and perfect. It provides a reliable theoretical basis for the continuous and steady development and utilization of geothermal resources.

Abstract:With the development of domestic oil and gas drilling toward 10，000 meters deep wells， the bottom hole temperature is getting higher and higher， so the drilling fluid needs to be cooled to protect downhole tools. In domestic drilling fluid cooling devices， the equipment is generally oversized， ultra-high and the cooling range of equipment is small. This paper starts from the introduction of the technical status of drilling fluid cooling devices at abroad. The working principle， advantages and disadvantages， and application range of four kinds of drilling fluid cooling devices， including natural cooling， open cooling， closed cooling and forced cooling， are emphatically analyzed in combination with domestic drilling conditions. In order to ensure the cooling effect of the cooling device， the paper analyzes the key technical problems of cooling mechanism， engineering adaptability， application limitation and equipment reliability in combination with the requirements of roads and environmental protection， and puts forward the technical research and development ideas of the cooling device of the cooling device in combination with the domestic drilling situation， providing guidance for the development of devices with strong adaptability， high reliability and remarkable cooling effect.

Abstract:There a lot of types of drill bit， used in geological exploration. In recent years PDC （Polycrystalline Diamond Compact） bits have been used widely and good technical and economical results obtained. However it is not enough well to design the bits and necessary to strengthen this work in order to get better results and wider application. In this field Russian drillers have made many works，obtained invention patents and got better results. Now the results are analyzed and researched， taking the three patents of them as researching objects， including cutting type double wing blade drill bit， stable drill bit， PDC spiral arrangement drill bit. The results may be have some reference value for us and should attract our attention.

Abstract:Hydraulic fracturing technology plays a key role in the efficiency exploitation of low-permeability oil-gas and geothermal reservoirs. In order to study the extension pattern of hydraulic fractures within the hot dry rock， the effect of flow rate and viscosity of fracturing fluid and horizontal geo-stress difference on the morphology of hydraulic fractures were investigated by the cohesive zone method （CZM）， and the combination of the above fracturing process parameters was optimized using orthogonal tests. The results show that the flow rate of fracturing fluid has a significant effect on the length of the hydraulic fracture， whereas the viscosity of the fracturing fluid has a significant effect on the width of the hydraulic fracture. The increase in the flow rate and viscosity of the fracturing fluid promotes the emergence and extension of branching fractures. When the horizontal geo-stress difference is 1MPa， the model established in this paper can obtain the best fracturing modification effect under the conditions that the fracturing fluid flow rate is 0.004m³/s and the viscosity is 0.07Pa·s； As the flow rate and viscosity of fracturing fluid exceed 0.004m³/s and 0.07Pa·s respectively and continuously increase， a decrease in the length and width of the hydraulic fracture will occur. Therefore， it is considered that the continuous improvement of fracturing effect cannot be achieved blindly by increasing the flow rate and viscosity of the fracturing fluid during the actual fracturing process. The findings of this study are expected to provide significant support in predicting the fracture extension behavior and the optimizing the fracturing parameters during the exploitation of hot dry rock geothermal resources.

Abstract:The drilling rig derrick structure will be damaged and destroyed to different degrees due to various reasons during the production process. In order to solve the problem of damage identification in the health monitoring of oil derrick structure in a complex working environment， a method of damage identification of derrick structure based on the generalized flexibility matrix is proposed. Compared with the flexibility matrix method， the generalized flexibility matrix only needs the first few low-order intrinsic frequencies and corresponding modal shapes to ensure the accuracy of the calculation. In the process of constructing the damage control equations， the matrix block solving method is adopted. Compared with the traditional method that requires the expansion of the element stiffness matrix to the overall stiffness matrix dimensions， the proposed solving method only needs to expand the number of rows of the element stiffness matrix accordingly， while the number of columns remains unchanged， so that the computation requirements for constructing the damage identification control equations can be greatly reduced. Finally， taking the K-type steel derrick structure as a numerical example， the results show that the method has great recognition effects for different damage locations and degrees and can be used for damage diagnosis or health monitoring of other large structures.

Abstract:During the construction of diaphragm wall using hydraulic grab， the grab needs to maintain vertical to ensure the accuracy of the side wall trench formation. When the excavation part of the grab interacts with the soil， the load acting on the grab has the characteristics of transient multidirectivity and non-uniformity， which leads to the deviation of the grab lowered by the steel rope and damages of the verticality of the trench wall surface. This article established a multi-body dynamic model of hydraulic grab and a clay soil layer model. Through the combination of multi-body dynamic and discrete element method， the tilt of the grab during the construction process of the hydraulic grab in the clay soil layer is analyzed， and an electro-hydraulic proportional speed control circuit to control the movement of the main hydraulic cylinder of the hydraulic grab is designed. Through joint simulation， the influence of the control signal of the main hydraulic cylinder on the tilt process of the grab is emphatically discussed， which provides a basis for further research on the hydraulic grab deviation correction system and control strategy.

Abstract:The M6 coal seam in Jintai Coal Mine has complex occurrence characteristics such as roof and floor breakage， apparent dip angle controlled by double dip angle （XZ view inclination 17°， YZ view inclination 3°）， thin seam thickness （1.08~1.68m） and large variation in thickness. In the construction of directional drilling along strata， there are some problems such as difficulty of actual control， easy deviation from coal seam into unstable roof and floor， lower construction efficiency and ineffective penetration in multi-branch hole construction. Based on the calculation formula of apparent dip angle， this paper introduces the dip angle parameter of borehole along the working face to optimize the trajectory design method for the plane turning section of borehole， and carries out the verification test in Jintai Coal mine. The results show that： Compared with the original trajectory design method， the optimized trajectory design method can keep the borehole drilling along the middle of the coal seam， overcome the interference of the thickness change of the coal seam， and realize the accurate drilling along the coal seam of the plane turning section of the borehole， and the effective footage rates are 48.82%， 76.72% and 100%， respectively. The gas monitoring data of test borehole No. 8~10 show good gas extraction effect.

Abstract:Pre-packed screen pipes and gravel packing are widely used in geothermal exploitation， hydrological observation and other projects. The main working parts are gravel layer and pre-packed layer. In this paper， the permeability of quartz sand was researched which is commonly used as the pre-packed material. Through adjusting the particle size and fine particle content of the sand samples， the permeability of quartz sand before and after consolidated in saturated state is tested， the effects of the particle size and gradation on the permeability of quartz sand before and after consolidated are analyzed， and the permeability difference in the same conditions is also analyzed by sorting the tested data. The results show that the permeability coefficient of sand samples decreases with the particle size. Changes in medium sands is the biggest and smaller in fine sand. The permeability coefficient of sand samples decreases as the fine particle content increases. The minimum permeability coefficient of composite sand is smaller than that of the sand that constitutes its fine particle group. Under the same conditions， the permeability of loose coarse quartz sand is better than that of the consolidated quarts sand， and the permeability of the medium and fine consolidated quartz sand is better than that of loose quartz sand.

Abstract:In response to the frozen issues in subway tunnel constuction in Tianjin area where complex hydrogeological conditions exist such as water-rich sand strata， the laboratory model experiments and numerical simulations was combined to investigate the effects of cold media tempreture and seepage velocity on the frozen temperature field， closure time， and growth of frozen walls in sandy soil. The research findings indicate that as the cold media tempreture decreases， the temperature gradient near the frozen pipe becomes steeper， and the frozen wall becomes thicker. In the presence of seepage， the seepage water transports cold energy from the upstream to the downstream， which impedes the development of the frozen wall to the upstream direction while promotes it to some extent to the downstream direction， which leads to the uneven thickness of the frozen wall. Ultimately， the shape of the frozen wall changes from circular in still water to heart-shape. In practical engineering， measures such as grouting to reduce the seepage velocity and lower cold media temperature can be used to cut the clolure time and finally ensure a smooth frozen process.

Abstract:The support chassis of large drilling equipment， serving as the support platform， is commonly assembled by welding numerous steel plates together. The residual stresses and deformations caused by welding have a certain impact on the strength and stiffness of the chassis. In this study， the finite element analysis method is applied. A finite element model is established for a representative T-type welded joint in the large support chassis， using a Gaussian moving heat source. Four different welding sequences and welding speeds are adopted to analyze their effects on welding stresses and deformations. Optimized welding sequences and welding speeds are obtained. Based on this， an overall welding scheme for the chassis is optimized. A comparative analysis is conducted on the welding stresses and deformations before and after optimization. The results show that the residual stress is reduced by approximately 7% and the maximum deformation is reduced by approximately 26% after optimization. The research results can provide reference for the formulation of welding processes.

Abstract:In order to solve the problems of the subsea template was frequently lifted to the deck to replace the battery due to insufficient battery capacity， during the deep-sea exploration of the ship HYSY 708， a 3000m off-line battery distribution manager was designed and manufactured. The system is mainly composed of control cabin， deep-water battery pack， watertight cable， etc.， which can independent complete the power management and output of 4 deep-water battery packs. Made of high-strength aluminum alloy， the system can withstand pressure not less than 30MPa， Using PLC as the core controller， the control program is written. Through laboratory experiments， the control function is verified， and the switch of battery pack can be realized stably. In May 2023， the field application was carried out in the depth of 1800m in a certain sea area of the South China Sea， and the underwater operation time of the subsea template was successfully increased from about 3 days to more than 10 days， greatly extending its working time in the seabed， saving valuable working time for the ship HYSY 708， and successfully assisting the ship to complete the survey task.

Abstract:In order to solve the problem of severe wearness and frequente tripping work in the hard plastic strata of Shaximiao Formation in Wubaochang， the research on the rock breaking performance of an axe-shape cambered PDC cutters is made. Firstly， the X-ray diffraction test and triaxial mechanical test are used to obtain the rock properties and mechanical parameters of the formation， then the finite element simulation and test are combined to study the rock breaking performance of the axe-shape cambered PDC cutters. The results show that the axe-shape cambered PDC cutters mainly break rock by the combined action of shearing， extrusion and plowing. Compared with the conventional PDC cutters， the axe-shape cambered PDC cutters have stronger rock-breaking ability and stability， which can effectively reduce the abnormal vibration of the bit， improve the bit life， and the rock breaking mechanical specific work can be reduced by 2.2%~8.2% at different wear height （0~3 mm）. According to the test results， the rock breaking performance of the axe-shape cambered PDC cutters is higher than that of the conventional cutters by 11.39%， and the average cutting force error between test and simulation is only 7.46%， which verifies the correctness of the simulation model. This study shows that the axe-shape cambered PDC cutters are of great significance in improving the rock breaking performance in hard plastic formation.

Abstract:The main reservoir of Longfengshan Gas field in Changling Fault Depression is distributed in Yingcheng and Huoshiling Formation where the igneous rock is abundant. The high quartz content and abrasive nature of the reservoir rock results in low ROP and short footage per bit， which greatly increases the non-productive time such as tripping and bit changing and thereby seriously restricts the drilling speed. In this paper， the rock mechanic section is established and corrected by the well logging data and the rock mechanics experimental study. A 6-blade shaped PDC bit was designed for the volcanic rock formation in the block by PDC bit composite design and optimization. It has been applied in 3 wells，compared with other common PDC bits， the average footage is increased by 42.2% and the average machine drilling speed is increased by 36%， which shows a remarkable effect for drilling speed up and cost reduction.

Abstract:The control and prevention technology for unstable-rock is the key to guarantee the safety and stability of unstable-rock. This paper analyzed the merit and demerit， application condition， engineering setting principle and selection program of the control and prevention technology， which is devided into three kinds， i.e.， active technology， passive technology and assisted technology. Application conditions of each technology should be considered when these technologies were designed. Each technology should be selected based on the engineering setting principle， and the treatment measure with multiple technologies to control and prevent unstable-rock should be duly selected. The selection of technology for unstable-rock engineering should follow such process of checking the basic information of unstable-rock → evaluating the state of unstable-rock → selecting technology → analyzing the result of selected technology， thus the key parameters of each part of this process were confirmed to select the suitable technology. This research achievement could provide the theoretical foundation and key technology support for unstable-rock engineering.

Abstract:The research and application of rapid drilling techniques for drilling through severely permeable and collapsed formations is one of the urgent issues to be addressed in solid mineral exploration geological core drilling. Combined with the practice of drilling engineering in Yangshan gold mine in Gansu Province， in view of the serious leakage and collapse of the long hole section， this article summarizes a set of drilling techniques suitable for rapid exploration in this mining area， which includes wire-line core drilling and full-hole drilling blind drilling technology used to quickly passing through the formation， and cement temporary plugging， casing plugging， reaming， following pipe used to plug the formation，and analysis their application effects. At last， the understanding and thinking of drilling in the formation were proposed. This article is intended to provide a reference for drilling in similar formation.

Abstract:Duiring the construction of ZK30-1 hole， a detailed investigation hole for coal resources in Guojiatai， Jingtai County， Gansu Province， serious collapse accidents happened in the long hole section caused by forcibly lifting the “water drill”. In this paper， the main reasons why the hole wall collapse were analyzed. Large cumulative coal thickness exists in the collapsed strata， loose and broken surrounding rock structure are the geological factors. The mismatch between the performance of the flushing fluid and the lithology of the formation is the main technical factor. By introducing low viscosity and strong suppression flushing fluid， gently pressing and slowly rotating during the hole cleaning process， and circulating with small pump volume， the collapse of the hole wall was restored， and the hole was successfully finished. Coal drilling construction has strict requirements for flushing fluid performance， and more strict when wire-line core drilling was used to extract core powder. It is necessary to strengthen monitoring of flushing fluid performance changes during mud preparation and drilling processes.

Abstract:In view of the serious leakage and poor plugging effect of bridge plug plugging materials in deep fractured formations of Daqing Oilfield， the thermoplastic composite plugging technology was formed by introducing elastic adhesive materials and mixed with bridge plugging materials. Laboratory tests were carried out in 25 deep wells of Daqing Oilfield. The results show that the thermoplastic composite plugging technology has better plugging effect than that of the bridge plugging technology. The plugging success rate is 100%， the pressure-bearing is 7.5MPa， and finishing drilling ahead of schedule due to vicious leakage has not been occurred.

Abstract:Taking the Pangusi-Wulongkou fault zone in Jiyuan City， Henan Province as the research object， by analyzing the geothermal features in the Wulongkou Town， this paper put forward suggestions for the industrialization of geothermal resources. The research shows that the geothermal energy in the study area is controlled by the Pangusi and Wulongkou fault belt， and the geothermal fluid receives the recharge of atmospheric precipitation in the Pangusi Fault Belt in the northern mountainou area. The geothermal energy is the type of convective medium-low temperature， and the geothermal reservoirs is featured of zonal fissure. The main available thermal reservoirs are as follows： the Quaternary loose rock reservoir， the Cambrian-Ordovician carbonate reservoir and the Archaean gneiss reservoir. It can be used for geothermal heating， health and wellness， hot spring vacation， agricultural production and mineral water production and other industries.

Abstract:In the geothermal resources exploration and evaluation project in the main urban area and the eastern new urban area of Zhengzhou City， the Neogene Minghuazhen Formation and Guantao Formation is the target layer， where the problem of unstable coring quality exists in the early stage of exploration. Through the analysis of geological and engineering factors which affect the coring quality， it was found that the early used Chuan7-4 type single move double tube coring tool with slip-collar type core gripper is difficult to adapt to the Neogene strata which is of large difference of cementation degree， complex and changeable. In view of the factors that affect the coring quality， calcified mud was used， drilling parameters were optimized， structure of the drilling bit was improved， double action core gripper with card plate and slip-collar was designed and processd. As a result， the coring rate was effectively improved and the problem of instable coring quality was solved in the subsequent exploration construction.

Abstract:Vertical drilling technology is commonly used in mountain tunnel investigation with complex geological structure， however， it is difficult to meet the requirements of the terrain change observation adits investigation. Taking an terrain change observation adit investigation project in Xichang as an example， a method to solve the two key problems of detailed surrounding rock classification and water inflow estimation in tunel investigation based on horizontal drilling technology is put forward. Detailed logging of the joint fissures in full-hole horizontal drilling cores and the joint fracture linear density statistics are collected. Combined with the developed orientation and space of the joint fractures in the project site area， the standard rock mass model is established. Through statistical analysis of the standard model， the conversion factor K of the one-dimensional core fracture linear density and the three-dimensional volume joint number J_v of the rock mass is finally obtained. After that， the rock mass integrity index K_v and BQ values of the tunnel surrounding rock are calculated according to the standards and specifications， and then the classification of tunnel surrounding rock can be more detailed divided. In the process of drilling， horizontal drilling can be used to accurately judge the location of tunnel water inflow and measure it， which provides accurate calculation parameters for the calculation of tunnel water inflow.