Abstract:It is of great significance to carry out intermediate-depth and deep ice-core drilling projects in polar regions for obtaining paleoclimate information and predicting future ice sheet evolution. Since the 1960s， countries around the world have completed 26 intermediate-depth ice-core drilling projects and 14 deep ice-core drilling projects in polar regions. At present， there are still five deep ice core drilling projects in progress， which are Dome A， Beyond EPICA， MYIC， Dome Fuji and Hercules Dome. Russia is also planning a deep ice core drilling project at Dome B. At present， China has only implemented one intermediate-depth ice-core drilling project， and the depth of the deep ice-core drilling project has just broken through 800m. Compared with Europe， the United States， Japan， Russia， China has less drilling experience， low degree of equipment independence， and relatively backward technical level in the field of intermediate-depth and deep ice-core drilling technology. Therefore， China should actively develop deep ice-core electromechanical drill with independent intellectual property rights， accelerate the implementation of Dome A deep ice-core drilling project， carry out intermediate-depth ice-core drilling and ancient blue ice drilling projects， break through key technologies such as rapid ice drilling and directional ice-core drilling technology， so as to promote the development of China’s polar ice-core drilling technology and improve its influence in the field of polar ice core science.

Abstract:Percussion rotary drilling is an important method of drilling and widely used in geological exploration. Traditionally in percussion rotary drilling application of impact pulse is centric，but not eccentric. Russian experts have put award fragmentation of rock by application of eccentric impact pulse in order to improve the result of the fragmentation. That is a new concept and an innovation. The experimental research has been proved， that in percussion rotary drilling by eccentric impact pules in rock not only vertical normal stress are created， but also tangential shear stress created and it is beneficial to improve the result of rock fragmentation and rising of drilling rate. In drilling dolerite and marble at eccentricity E=1~2mm the mechanical drilling rate and bit penetration per revolution are increased substantially in comparison with E=0mm. Matching with the mentioned above the drill bit for eccentric percussion rotary drilling has been developed and the bit patent obtained， strengthening the result and role of the eccentric percussion rotary drilling further in geological exploration. It is suggested that further research on eccentric percussive rotary drilling should be carried out in China.

Abstract:Underground in-situ conversion is an inevitable trend of industrialized development of oil shale， and the autothermic pyrolysis in-situ conversion process （ATS） is a compound and efficient heating method to realize underground in-situ conversion of oil shale. In order to investigate the influence of different high-temperature carrier gases in the preheating stage on the effect of autogenous thermal in-situ conversion of oil shale， this paper took the oil shale in Fuyu area of Jilin， China， as an example， and injected four high-temperature gases， namely， nitrogen， air， steam， and carbon dioxide， into the preheating stage to conduct numerical simulation analysis， and compared the differences in the final oil and gas yields and the energy recovery rates. Taking the high-temperature nitrogen injection group as the control group in the preheating stage， the results showed that the time needed to complete the extraction by injecting high-temperature air， steam and carbon dioxide was reduced by 22%， 39% and 12%， respectively， and the maximum energy recovery rate was increased by 55%， 86% and 23%， respectively， and the total oil production was reduced by 5%， increased by 18% and reduced by 11%. From the perspectives of mining completion time， energy recovery rate and total oil production， steam injection preheating had the best effect. Therefore， a comprehensive comparison showed that the autogenous thermal extraction method of steam injection preheating could effectively increase the oil production， reduce the time required for extraction， and improve the energy utilization rate.

Abstract:The pressure holding coring technology can keep the extracted core under in-situ condition， minimize the loss of important data in the core， and then accurately obtain important formation parameters which can calculate the reserves of mineral resources. In this paper， the ball valve mechanism of pressure core sampler is studied by numerical simulation， and its dynamic characteristics are explored to optimize the ball valve mechanism， and increase its sealing reliability. The results show that with the increasing of thrust force on the ball valve， the shorter the closing time of ball valve， but the vibration generated increases， which is easy to cause seal failure. Thus， the small thrust force is selected to help improve the sealing reliability. With the decreasing of friction coefficient， However， the vibration generated increases， making the leakage risk of ball valve much bigger. When the ball valve is closed， the pressure simulation of 30MPa is conducted. The maximum contact stress and the maximum strain are both within the allowable range of ball valve.This study are meaningful to guide the optimal design of ball valve mechanism and improve its working reliability.

Abstract:There are many challenges in the process of geological drilling， among which the problem of leakage is particularly prominent， especially in fractured formations， which occurs more frequently. Therefore， it is of great practical significance to develop a drilling fluid system suitable for loose broken formation to maintain rapid drilling in broken formation. The inert material and formula suitable for plugging in the broken formation were determined by optimization experiments. Meanwhile， Super Absorbent Polymer （SAP） was prepared by aqueous solution polymerization， and the water absorption ratio was more than 100 times under the condition of 0~100℃. The non-permeable drilling fluid loss instrument was used to optimize the particle size and concentration of SAP， and 0.3% of 4~8 mesh SAP was the best choice. Finally，the formula of the drilling fluid system for plugging the broken formation was optimized： water+8%bentonite+0.1%xanthan gum+0.6%HV-CMC+2%walnut shell+1%mica sheet+2%specialty fiber+0.3%SAP of 4~8 mesh. The drilling fluid system can completely plug the sand filling bed of 10~20 mesh， the loss is 0 mL at 0.69MPa pressure， and has good rheological stability in the range of 0~60℃. The apparent viscosity is between 25~48mPa·s， the dynamic shear force is 6~18 Pa， the API filtration loss is 7~11mL， and the lubrication coefficient is 0.311. It shows a good application prospect in plugging loose broken strata.

Abstract:With the continuous improvement and expansion of the application scope of active magnetic measurement technology represented by SmartMag Drilling Target-Hitting Guide System， it will be more applied in high-temperature underground environments such as geothermal well development and deep-sea mineral resource exploration in the future. High temperature often becomes a bottleneck problem that restricts the normal operation of instruments.In order to further improve the temperature resistance performance of the SmartMag system， this article adopts passive thermal management method and uses finite element method to simulate the phase change heat storage characteristics of the vacuum flask. It explores the optimal coupling length of the heat absorbing body and compares the phase change materials with the best temperature control ability horizontally. It analyzes the changes in axial temperature and phase state of the heat absorbing body inside the vacuum flask over time.The results show that the optimal coupling lengths are 400mm for the upper absorber and 250mm for the lower absorber. After operating the insulation cylinder at 150℃ for 6 hours， the utilization rate of phase change latent heat of the upper absorber is 96.7%， and the utilization rate of phase change latent heat of the lower absorber is 70.5%. The minimum temperature of the circuit board is 63.48℃， and the temperature control effect of low melting paraffin is the best.

Abstract:Dengying Formation stratum has become an important stratum for Sinopec to increase natural gas storage and production in Sichuan Basin and improve national energy security. Due to unclear understanding of the mechanical properties of dolomite in the ultra-deep high-temperature Dengying Formation， it often leads to instability of the dolomite wellbore. By conducting uniaxial compressive strength experiments of dolomite at 25℃ （room temperature）， 100℃， 150℃， 180℃， 200℃， and 220℃， the uniaxial mechanical strength and deformation characteristics of dolomite were revealed. The dolomite in the Dengying Formation will exhibit significant brittleness enhancement with increasing temperature within a certain temperature range （100~220℃）， which is believed to be the reason why the peak strength of the dolomite in the Dengying Formation decreases with increasing temperature. Based on the strain Equivalence principle， the damage deformation constitutive model of dolomite in Dengying Formation after high temperature is established. The comparative study shows that：（1）The stress-strain curve drawn by the constitutive model is in good agreement with the experimental curve， and the model can fully reflect the damage process of dolomite in Dengying Formation at different temperatures； （2）This model can accurately characterize the strength and deformation parameters of dolomite at different temperatures， providing a more scientific and rigorous model for wellbore stability analysis， and improving the geological understanding of ultra-deep to ultra-deep complex formations in key areas and the ability to prevent and control complex faults during drilling and completion.

Abstract:The prediction of the hook load during casing insertion is one of the key factors for success. Due to its special wellbore trajectory， the frictional resistance during casing insertion in horizontal wells is higher than that in conventional wells. Therefore， accurately predicting the frictional resistance of casing insertion plays an important guiding role in the design and construction of horizontal well cementing. At present， many friction prediction analysis models have been developed in the industry， and relevant theoretical research and case analysis have been carried out. The commonly used analysis methods include Soft-String Model， Stiff-String Model and finite element method. Subsequent scholars used various theoretical methods to consider the friction analysis model of casing under various stress conditions on the basis of the three methods， but there is currently no relevant research that summarizes and analyzes the advantages and disadvantages of existing model algorithms， making it impossible to conduct model optimization in specific applications. Therefore， according to different basic theories， this paper classifieds and analyzes the current casing friction models， and discusses the existing technical bottlenecks in casing friction research and prediction as well as the next development direction， in order to provide guidance and help for the in-depth integration development of casing friction analysis in the future.

Abstract:As the core functional unit of riserless mud recovery system， the mud lifting centrifugal pump drives the mud stored in the suction module to carry rock cuttings recirculate back to the drilling platform through the return pipeline. Previous designs of the riserless mud recovery system primarily employed disc pumps as the lifting unit， with specific structural design and theoretical analysis conducted around them.However， there has been limited research on multi-stage centrifugal pumps， which offer superior hydraulic performance. In this study， we focus on the theoretical basis and specific parameters of a multi-stage centrifugal pump，and develop a computational model using CFD-DEM coupling calculation to conduct a full-scale flow field simulation.This simulation investigates the impeller design， flow field characteristics， internal particle distribution patterns， and mud rock transport patterns within the pump.The results validate the centrifugal pump’s good particle permeability under design conditions.Furthermore， we conducted hydraulic performance tests on a centrifugal pump prototype using a mud lifting test bench. The test resultsindicate that the pump exhibits satisfactory operational working characteristics and hydraulic performance， meeting the design requirements for application in deep-sea riserless drilling operations.

Abstract:Aiming at the low efficiency of horizontal directional drilling in hard formation， the self-sharpness of the bit was improved by the hard brittleness of FeCoCu pre-alloy matrix and the hard silicon carbide particle to weaken the matrix. The layered structure design is used to alternate the high and low wear resistance layers along the radial direction of the bit. The thickness of low wear resistance and high wear resistance were designed to be 1.0~1.5mm and 2.5~3.5mm respectively， to realize simultaneous wear of high wear resistance layers and low wear resistance layers and improve drilling efficiency. The bits have been successfully applied to horizontal directional drilling in hard potassium feldspar granite formation， using the combination of FeCoCu pre-alloy matrix and stratified matrix structure， with the average ROP of 0.8~1.5m/h and the drilling life of 30~40m. Compared with the ordinary concentric sharp tooth bit， the ROP has been increased by about double， and the drilling life has been increased by more than 30%.

Abstract:The advancement in the drilling technology of large displacement wells has provided a great potential for significantly improving the efficiency of extracting unconventional energy sources such as shale gas. However， the high friction between the drilling rods and the wellbore during the process of large displacement well drilling reduces the drilling efficiency. One effective solution to address the technical challenges of high friction and severe drag in the current construction process of extended reach wells or horizontal wells is to incorporate drag reduction tools capable of generating oscillations into the downhole drilling tool assembly. However， currently， there are few types of such tools， and they generally suffer from complex working mechanisms， difficulties in structural design， and excessively high tool pressures. Therefore， this paper proposes a reverse feedback oscillating jet pressure pulse drag reduction tool with low pressure and no moving parts. Visual experiments and numerical simulations were conducted on this tool， and the working mechanism of the jet oscillator was elucidated by monitoring the evolution of the internal flow field of the tool. The results showed that the generation of pressure pulses is composed of phenomena such as the wall attachment and detachment of the jet， as well as the growth and dissipation of internal vortices in the tool. Furthermore， the pulsation performance of the tool was studied， revealing its operational performance under different conditions such as flow rate， drilling fluid density， viscosity， etc. Structural optimization was carried out for conditions of low drilling flow rates， expanding the operational range of the tool. This paper can provide new insights for the design of large displacement well drilling tools.

Abstract:During the drilling process， accidents of screw drilling tools breaking and falling often occur. For lightweight falling objects caused by accidents such as detachment of the outer shell of the screw drilling tool and core pulling due to rotor fracture， the applicability and success rate of using conventional slip salvage barrels are insufficient. Based on this， a screw drilling tool three slip eccentric fishing barrel was designed， which drives the upper， middle， and lower slips to contract and clamp the conjugate annular space through the conical guide surface of the fishing barrel， achieving effective fishing of this type of falling objects. The eccentric arrangement structure design of the three slips increases the effective clamping area and improves the comprehensive fishing force of the fishing barrel on the screw drilling tool. Based on the working principle of the fishing barrel， a calculation formula for the conventional clamping force of the slip and the squeezing clamping force was established. By comparing， it was found that the conventional clamping stress of the slip required for the three eccentric fishing barrel can be reduced by 50.46%， and the bite depth of the fishing tool can be reduced by 13.92%. The trial produced fishing tube has been put into salvage practice on the construction site， indicating that its structural design is reasonable and its salvage performance is reliable.

Abstract:The development of automatic monitoring system for core filling rate is to fill the shortage of core condition monitoring in the coring process. The automatic monitoring system is composed of main controller， reserved temperature and pressure monitoring module， Hall sensor module， data storage module and serial debugging module. Among whcih， the principle of core status monitoring is based on Hall effect. The coring speed range of the system can be monitored in 0~30 mm/s， and the monitoring accuracy is about 1%. The system uses STM32 single-chip microcomputer， large-capacity memory， high-speed USB interface and so on， which has the functions of online debugging， programming and upgrading. The sea tests were made， and the results show that the system can automatically monitor the process of core penetration into the core tube at a water depth of 3000m （a hole bottom pressure of 0~35MPa）， which can provide theoretical guidance for the selection of field sampler type and the optimization of working parameters of the sampler， and has a broad application prospect.

Abstract:The Paleogene sedimentary thickness in the Sanmenxia Basin in Southern North China is large and continuously distributed， with developed dark mudstone. Through the deployment of drilling projects， new discoveries of oil and gas in small and medium-sized basins can be assisted. However， the geological environment for drilling in this type of reservoir is complex， with frequent sand and mudstone interlayers， which can easily cause engineering difficulties such as bit mud entrapment， wellbore collapse， block falling， coexisting risks of leakage， and difficulty in drilling. Through the optimization of drilling tool combination and wellbore structure， research on drilling fluid technology in different sections， development of PDC irregular tooth drill bits， and research on the drilling process of “low speed + medium drilling pressure + screw + high-efficiency PDC drill bits”， effectively solved the problems of wellbore stability and drill bit selection. In the actual drilling of Well YXD1， the average mechanical drilling speed of comprehensive drilling reached 5.67m/h， that improved 30%， which shortened the drilling cycle by 10 days compared to the design. Innovations have formed a “new， superior， and fast” drilling and completion technology system for sand and mudstone interlayers in the Sanmenxia Basin， including a mud pack drilling fluid technology system， a long open hole wellbore protection drilling fluid technology system， an efficient PDC shaped cutter drill bit acceleration technology for sand and mudstone interlayers， and a “two low and one high” variable density cement slurry cementing technology that can be promoted. This can provide useful reference for drilling engineering design and construction in similar regions.

Abstract:In the ultra-deep and ultra-shallow reservoirs （“double ultra” for short）， problems exist such as difficult coring operation， low success rate， high operation cost， and lack of reference experience. In view of this， the analysis of the coring difficulties without risers is carried out， the corresponding technical countermeasures are put forward， and a set of efficient coring scheme is formed. The results show that in the “double ultra” environment， the reservoir is dominated by unconsolidated and loose argillous sandstone， and the coring operation faces the problems and challenges of “blocked core”， the difficulty of controlling displacement and bit weight， and the high cost of ultra-deep water operation. The Rb-8100 fully enclosed conserved coring tool and HSC043-8100 coring bit are selected， corporated with small perameter mode of small displacement （200L/min）， low speed （15~40r/min） and stepped bit weight （2~10t）. The self-made net diverts seawater at the bit and protects the bottom core. The pilot test of riserless coring was carried out in “double ultra” gas field in South China Sea， and the core recovery reached 100%. It is the first time to realize the efficient coring operation in “double ultra” reservoirs， and lays an important foundation for the later development of ultra-deep and ultra-shallow reservoirs gas field.

Abstract:In the drilling construction of high-temperature geotherm in the Tianyang Basin， affected by the lithology and high temperature of the hard rock strata of the metamorphic rock system， the cone bit has low mechanical drilling efficiency， serious wear， and short service life， which seriously affects the drilling construction. As a result， the application of PDC bit was explored. Aimed at the lithological characteristics， the key technologies such as the selection and layout of bit body， blade， profile and composite pieces were explored and optimized in drilling practice. A PDC bit with good impact resistance and suitable for metamorphic hard rock formations is developed， which effectively improves the mechanical drilling speed and reduces the drilling cost， which provides technical support for the smooth implementation of the high-temperature geothermal drilling project in the Tianyang Basin.

Abstract:The tight sand formation reservoir of the Xujiahe-2 Formation in Xinchang Structure, western Sichuan has failed to form large-scale commercial development for a long time due to the unbalance of cost of drilling and benefit of production. In view of this phenomenon, through the series of scientific studies on the key drilling processes based on the optimization of setting positions, the hole size, the hole trajectory optimization, the combined drilling of the drilling tool, the low cost of the rotating guide tool in this paper. The comprehensive application of this technology in the block has achieved the breakthrough of shortening the shortest drilling cycle from 231.1 days to 95.7 days, achieved good application results, and realized the benefit development of the block.

Abstract:Taking a foundation pit project in Wuhan as the background， based on two observation indicators of water level drop inside and outside the confined layer pit and surface settlement outside the pit， a three-dimensional numerical calculation model for group well precipitation was established using finite element software ABAQUS for numerical simulation analysis. By setting multiple calculation conditions， under the conditions of different insertion ratios of suspended waterproof curtains λ， the influence of different well screen lengths L and filter tube burial depth H on the water level drop inside and outside the confined layer pit and surface settlement outside the pit was studied. The research results indicate that the impact of the insertion ratio λ on the water leverl drops inside and outside the confined layer pit and the surface settlement outside the pit is much greater than that of the length L and burial depth H of the well screen in the dewatering well. When the λ is between 0.4 and 0.6， there is a large space to increase the water level drop inside the confined layer pit or decrease the water level drop outside the confined layer pit by changing the length L and the burial depth H. When λ exceeds 0.6， it has a good water blocking effect. The buried depth H of the well screen should be located at the top of the confined aquifer， and the length of the well screen L should not exceed 0.4 times the thickness of the confined aquifer M.

Abstract:This paper focuses on the pressure shock wave generated by the electric explosion of the wire acts on the hole wall of the soil layer and form the belled piles caused by squeezing the soil at the bottom of the pile. The relationship function and simulation model between the explosive energy of the wire and the shock wave pressure are established， and the relationship between the discharge parameters and the shock wave intensity is analyzed. The relationship between shock wave pressure and soil deformation is established， and the pressure required for the deformation of clay soil is calculated. The models of belled pile and equal diameter pile were made to verify the deformation characteristics of soil under the electric explosion of the wire， and the bearing capacity and pullout resistance of the two piles were compared and analyzed. Based on the electrical and technological parameters of the high-voltage pulse bottom expanding technology model test， the first high-voltage pulse belled pile with a diameter of 0.8m was constructed in China， and the “irrigation-expansion” integrated construction method was developed.

Abstract:Drilling is the most direct engineering technology means for the exploration and development of energy and mineral resources. As a powerful tool for breaking rock and soil， downhole power drilling tool have the advantages of reducing consumption and increasing drilling speed， as well as reducing the risk of downhole accidents， it either directly drives the bit to form sliding drilling， or combines the top drive （or rotary） to form composite drilling. In order to prompt more technical personnels to understand the downhole power drilling tool， and develop new functions and new instruments based on its drilling advantages and technical characteristics， this paper introduces the use， main type， working principle and development history of the downhole power drilling tool from the perspective of popular science， and compares the advantages and disadvantages of different downhole power drilling tool. Finally， combined with the new requirements posed by the new drilling situation of deep wells， ultra-deep wells on the drilling tool， techniques and so on， as well as the application trend of other new technologies in drilling engineering such as materials， measurement and control， intelligence， etc.， it pointed out the upgrading and technological innovation development direction for the current mainstream downhole power motor.

Abstract:Total content of 《Drilling Engineering》 2024