Abstract:Ocean scientific drilling is an important means of scientific exploration and research of the ocean floor， and has extremely important significance in many fields such as earth science， life science， and resource exploration. Circulation Obviation Retrofit Kit （CORK） is an important supplement to ocean scientific drilling. CORK can achieve the transformation from short-term sampling to long-term dynamic observation of the seabed environment. Over the past few decades， the technological means of underwater observation equipment have also been continuously improved in this process. CORK has derived four new versions based on the initial development of CORK， which have evolved from single layer sampling to multiple layer sampling and can also perform in-situ testing. The new round of ocean drilling program led by our country is about to be implemented， and it is urgent to increase the research and development efforts of CORK technology， use our own resources and talents to build an underwater CORK observation system， and lay a solid foundation for quickly entering the ranks of world maritime powers.

Abstract:The potential of oil and gas resources in southwestern margin of the Sichuan Basin is abundant， however the geological structure is complex and lack of adjacent well data， making difficult drilling construction. Well Chuanmaye 1 is a shale gas geological survey parameter well deployed in the west wing of the Wuzhishan structural belt in southwest Sichuan. The designed depth of the well is 3400m， and the actual completed drilling depth is 3635m. A temporary closure was adopted when drilling to 3437.58m due to the complexity， and side tracking was carried out from 2818m to the completed drilling depth. In response to drilling difficulties， multiple key drilling technologies are summarized， including the handling of small fish accidents in large-diameter boreholes， efficient and rapid drilling with long open holes and large diameters， open hole side tracking in complex formations， and silicon potassium based polymer anti-sloughing drilling fluid systems. These technologies solved the practical problems， ensured the geological objectives， and achieved significant application effects， which can provide reference for similar drilling projects in the same region and support the new round of strategic action for prospecting breakthrough.

Abstract:HDCS-2 well is a coalbed methane parameter well and production test well deployed in the Nileke Depression of the Ili Basin. Through optimizing drilling fluid parameters， high viscosity drilling fluid flushing， explosive loosening and other technical measures， the drilling complexity problems are solved including block falling， drilling tool obstruction during the tripping， and buried drilling in long open hole of the coal bearing strata， ensuring the completion of the project and the achievement of the geological objectives. Rock mineral analysis testing and scanning electron microscopy observation were conducted using samples from Well HDCS-2， and a three pressure profile was constructed based on logging data to analyze the mechanism of wellbore instability. Improved measures for subsequent projects are suggested as follows： three-section well configuration and a high shear anti collapse drilling fluid system should be adopted， high viscosity drilling fluid （drip） can be configured for well flushing when encounteres falling blocks in the well， slow drilling and tripping， optimizing the drilling tool assembly as well as equip drilling vibration hammer during drilling in coal bearing strata. The study can provide valuable practical guidance for subsequent coalbed methane drilling in the region.

Abstract:In the process of a series of geological core drilling projects in the hilly areas of southern China， a number of technical difficulties have been encountered， including the karst cave crossing in the karst cavity area， the safe drilling in the lost return layer at the bottom of the well， the coring problem in the loose mudstone， sandstone and gravel layer， drilling difficulty in the water-sensitive formation， the stable drilling in the strong deflecting area， and the relocation difficulty in the deep cutting area. Therefore， the following technical measures were taken in response to the above difficulties： （1）the “double casing+half filling”method is taken to cross the karst caves， （2） the comprehensive technical measures of “top leakage+plugging+lubricating drilling tool”； （3） the advanced coring with casing while drilling and multi-layer casing wall protection technology， and the special sampling drilling tool with aperture convergence and the telescopic leakage joint are innovatively applied， which significantly improves the core recovery rate， （4） a low solid-phase anti-sloughing flushing fluid and strengthening solid-phase control， reducing the rotation speed and back footage， as well as rapid casing support response to ensure the hole safety； （5） the calculation method based on the mechanical model of continuous beam wire-line coring drilling tool， and the measures of low pressure lifting， drilling rig foundation reinforcement and concentricity improvement are adopted to achieve the purpose of anti-deviation and straightening； （6） the efficient scheme using drones for relocation. The results of this paper provide an important reference for drilling construction under similar environment and complex geological conditions.

Abstract:In the exploration project of the Zhaishang Gold Mine in Min County， Western Qinling Mountain， drilling work was carried out to control the main ore veins in the southern ore belt of the mining area. According to past experience， the main ore veins in the southern ore belt have steep occurrences （78°~85°） and are unstable， characterized by a southward dip in the shallow part and a northward dip in the deep part. At the same time， most areas have thick overburden layers， with intense topographic cutting， making it difficult to roads and airports construction and drilling equipment transportation. The first near-horizontal borehole in the mining area was designed， where the EP1000 portable full-hydraulic drill was used， the horizontal drill frame kit was transformed， upgraded and processed， wireline coring technology was adopted， and the construction of a near-horizontal coring borehole with a length of 216.73m was completed. This is an innovation to implement a near-horizontal borehole under the condition of water-sensitive， complex strata and continuous water gushing in the borehole. It practices the concept of green exploration and provides a reference for similar engineering projects.

Abstract:The waste drilling fluid generated by drilling engineering can cause a series of impacts on the ecological environment， and it is required the comprehensive implementation of green exploration in the new round of strategic actions for mineral exploration breakthroughs， stricter requirements on the treatment technology of waste drilling fluid is posed. This article combines field research and laboratory experiments to analyze the pollution characteristics of the waste drilling fluid used at the Tengjia Gold Mine in Zhaoyuan， Shandong. Laboratory experiments are conducted to study the harmless treatment technologies for waste drilling fluid. The preferred agents of GPJ-1 （a gel breaker）， GXN-1 （a flocculant）， and GAC （a decolorizer） are optimized and processing by gel breaking， flocculation， adsorption， and decolorization treatment， followed by solid-liquid separation using centrifuges or filter presses， the solid phase is then treated with solidification. The experimental results show that after treatment， the pollution indicators of the waste drilling fluid have significantly decreased， meeting the secondary standards for comprehensive sewage discharge. The formulation “2% GPJ-1+0.5% GXN-1+1% GAC” was used to harmlessly treat the waste non-solid phase drilling fluid on the drilling site of Zhuguang project in Shaoguan， Guangdong， confirming the feasibility of harmless treatment technology.

Abstract:The Well Jichengye-1 is located in Chengde City， Hebei Province， which is a small-diameter shale oil and gas survey well， with a structural location in the Lujiagou syncline of the Kuancheng Depression in the Yanliao Rift Trough of the Chengde Basin. The geological condition of the drilling project is extremely complex， with not only water inflow and leakage problems， but also loose and fragmented carbon powder sandy shale in the Hongshuizhuang Formation of the target layer， high montmorillonite content in the clay mineral composition， strong water sensitivity， and poor wellbore stability. Drilling construction poses risks of collapse， leakage， and drill sticking， which puts high demands on drilling technology and flushing fluid technology. In view of this， a detailed analysis was conducted on the performance requirements of each well section for the flushing fluid in the encountered strata. A dedicated flushing fluid system for Well Jichengye-1 was developed and formulated. Orthogonal experiments were conducted on the flushing fluid ratio for the target shale layer， and the flushing fluid formula was determined as follows： water+3% Na-B+3%（soil weight） Na₂CO₃+3% KHM+1% GPC+0.2% K-PAM+0.2% Na-CMC+1.5% MSDS. Tailored flushing fluid maintenance measures were carried out， which has good application results in the actual drilling process， and can provide reference for similar drilling projects.

Abstract:During the drilling process in the covering layer of Zhumadian area in Henan Province， the Quaternary clay layer， sandy mudstone， loose sandstone unevenly interbedded with mudstone were encountered， resluting in difficult wall protection， prone to accidents such as block jamming， hole collapse and burial， and difficult in taking cores. Based on the geological conditions and the drilling construction data within the area， the dual-polymer anti-sloughing flushing fluid was used. In the on-site application， the stability of the hole wall was good during the drilling process of the long open hole well section， without any incidents of falling or collapes. The core recovery rate can meet the geological design requirements， moreover， the casing depth and construction cost were reduced.

Abstract:The no man’s land in northern Tibet Plateau has a high altitude and harsh climate， and it is difficult to ensure the transportation of construction materials. During the drilling process， problems happened such as thawing and collapse of frozen soil， strong cementation and hole shrinkage in mudstone， continuous breakage and water-gushing in long holes， and so on. In view of this， technical measures are taken to solve the problems in the drilling process such as optimization of drill assembly， flushing fluid systems， drilling tools and equipment， and the use of short-stroke dry drilling， gravity plus rod， follow-up pipe drilling， and drainage pressure relief. The project team has accumulated some experience of drilling construction， which provids effective geological drilling data and physical core data for the survey of energy resources in this region.

Abstract:In solid mineral exploration， the complex terrain of the work area poses significant challenges to the relocation of drilling equipment， and building roads or manual relocation involves high workload， long construction period， substantial environmental damage， and high safety risks. Taking the Chenjialun survey area in Anhua County， Hunan Province， and the Majiangyuan survey area in Jianghua County as examples， three types of multi-rotor drones were selected， and attention was taken on comparative analysis of the drone hoisting and transporting processes such as equipment disassembly and bundling， route planning， and flight hoisting， as well as their application effects. The application results show that drone relocation has advantages such as high efficiency， low labor intensity， and environmental friendliness. Compared with the traditional relocation methods， it contributes to the realization of green exploration. At the same time， suggestions were put forward in terms of enhancing the load-carrying and endurance capabilities of drones， improving the multi-control mode of drones， and optimizing the modular distribution and integration of drills. The advantages and application effects of multi-rotor drones under complex terrain conditions can provide useful reference for the relocation of drilling equipment in areas with complex terrain.

Abstract:The study of application of portable fully hydraulic drill is carried out in the exploration of Maoniuping rare earth mining area， and the performance and advantages under complex geological conditions are explored. The modular design improved the environmental adaptability of the drill. Advanced drilling technologies such as thin wall series drill rods and low solid flushing fluids are adopted to form a set of drilling technical parameters suitable for the fractured strata in the mining area， and the drilling efficiency and core recovery rate are successfully improved. Based on the engineering practice， the construction situation and application effect of portable drill have been discussed， and the existing problems and the countermeasures are summarized and proposed. The research shown that portable fully hydraulic drill have demonstrated significant applicability in drilling complex strata of rare earth minerals， which provides important references for the exploration and construction for this type of mineral.

Abstract:During the construction of rotary drilling rig， the efficiency of rock drilling is closely related to the pick arrangement of core barrel. The key pick arrangement parameters of core barrels are studied by using pick cutting test system. Three-dimensional load， crushing volume， deformation displacement， broken morphology and other data were collected during the test process. From multiple dimensions such as crushing specific power， cutting resistance， load fluctuation， and pick spin， the controlled variable method is applied to conduct pick cutting experiments， quantitatively evaluating the effects of cutting angle， drilling tooth deviation angle， cutting sequence， drilling tooth tip height difference， and drilling tooth tip trajectory spacing on rock cutting. Research has shown that there is an optimal combination of drilling tooth arrangement parameters that match the geological properties. Taking drilling into granite formations as an example， the optimal range of drilling tooth arrangement parameters was determined， which are： cutting angle 68°~72°， drilling tooth deviation angle 5°~15°， skip cutting， drilling tooth tip height difference of about 3mm， and drilling tooth tip trajectory spacing of about 30mm. According to the test results， the drilling efficiency is increased by 13.64% and the cost of unit footage is reduced by 39.13%. The research results are of great significance for guiding the arrangement of the core barrels， reducing the drilling tooth loss and improving the drilling efficiency.

Abstract:The oil-water relative permeability is a key parameter to characterize the effect of water injection in low permeability oil reservoirs. Due to the narrow pore size and large seepage resistance of low permeability reservoirs， the “end effect” of core leads to the inconsistency between the calculated oil-water relative permeability curves and the actual results， which affects the establishment of water injection development scheme of low permeability reservoirs. To avoid the influence of core “end effect” on the relative permeability， the CT scanning has been applied to monitor the in-situ water saturation profiles along the low permeability core at different time points. Based on the experience formula of oil-water relative permeability curve， optimal parameters of the relative permeability has been obtained by combining the oil-water flow methods in low permeability reservoirs， and the simulated annealing optimization theory. The results show that CT scanning test is a very effective test method which can not only monitor water saturation profile and water saturation characteristics in the central core， but also avoid the influence of “end effect”. The global optimal relative permeability curve has been obtained with the Simulated Annealing method. The test results of water saturation and the pressure difference at both ends of the core accord with the results of calculation. This method has the advantage of high goodness of fit and satisfactory effect， with the relative permeability less than 8%. This method is proved to be efficient and accurate for calculating oil-water relative permeability curves， providing a strong support and guidance for the development of low permeability reservoirs.

Abstract:The packer expansion tube technology has been developed for the hydrogeological exploration of wall protection and the repair of damaged well pipes. It has the characteristics of low cost and simple process. In order to make the packer meet the requirements of the expandable tubular， the expansion mechanism of the packer is improved. The packer is used to test the pipes with different properties. According to the test results， 316L stainless steel is selected as the expandable tubular. In order to study the relationship between the expansion pressure and the change of the length and thickness of the expansion tube during the two expansions of the packer-type expansion tube， the expansion process of the expansion tube with ?219mm and wall thickness of 4mm was numerically simulated by Abaqus software to obtain the change of stress and strain during the expansion process， and field tests were conducted on the expansion tube with the same specifications. Then， by comparing the simulation results with the test results， it is concluded that the simulation results are basically the same as the actual demonstration results， indicating that the numerical simulation results can be used as a reference for the actual construction.

Abstract:This paper focuses on the diamond single crystal impregnated columns. To determine the wear resistance of impregnated column under different diamond parameters， a comparative wear resistance test for multi-level diamond single crystal impregnated pillars is designed. The preliminary conclusion obtained through experiments is that the wear ratio is relatively high when the diamond impregnated columns are graded with three mesh sizes of 20/25+35/40+60/70， and the design of a double chamfer structure can improve the wear resistance of diamond impregmented columns by about three times. The impregnated pillar was used as a secondary tooth inlay in ?152mm and ?215.9mm compound non-coring bit， and drilling tests were conducted on both bits. Which has a highier drilling efficiency and extremely slight wearness. The impregnated column studied in this article has great potential for engineering applications and is expected to provide reference for the design and selection of drilling tool materials.

Abstract:The continuous circulation valve can maintain the circulation of drilling fluid when drilling is stopped， which can effectively solve the sediment at the bottom of the hole and the fluctuation of pressure at the bottom of the hole， especially for offshore oil and gas horizontal drilling. In this paper， a continuous circulation valve is designed， the structure and working principle of the continuous circulation valve are introduced， the force analysis and structural optimization design are conducted on the strength of the body under extreme working conditions， and the side opening of the bypass valve with a safety factor greater than 1.2 times was selected； A finite element stress analysis is conducted on the bypass valve， which comprehensively analyzes the stress distribution and sealing pressure. The influence of changes in the half cone angle of the sealing pair and the thickness of the valve on the stress and sealing effect of the bypass valve is obtained. The half cone angle of the sealing pair， α=30°， and the thickness of the valve core plate， δ=8mm， are optimized. and the bypass valve sealing test and body strength test are conducted， proving that the strength and sealing performance of the continuous circulation valve meet the actual usage requirements under the ultimate internal pressure of 35MPa and ultimate tensile force of 3503kN.

Abstract:Formations with developed fractures are more likely to receive better water supply， and severe leakage during drilling requires the use of cement for sealing， but this can easily cause reservoir damage problems. In this paper， a geothermal temporary plugging cement is developed based on degradable fibers， which has a low permeability during drilling， plays the role of wall protection and plugging， and partially degrades to provide a channel for the output of geothermal fluids after the completion of the well. Based on the preparation， modification and characterization of PVA-coated PLA fibers （PVA-PLA）， the effects of the modified fibers on the performance of the cement paste and the performance of cemented cement stone before and after high-temperature hot-water immersion were investigated and the mechanism was analyzed. The results showed that： the regulation of the degradation properties of polymer fibers can be achieved by coating， heat treatment and silane modification； the compressive strength of PVA-PLA fiber cementite at 60℃ was 19.8MPa at maximum， and the porosity was 28.88% at maximum after immersion at 90℃， which was most in line with the requirements of low-temperature plugging and high-temperature unplugging； the coating of PVA at 60℃ reduced the contact between PLA and cement matrix， and the PVA-PLA fiber cementite at 90℃ was more suitable to the requirements of low-temperature plugging and high-temperature unplugging. The PVA membrane dissolved and PLA exposed to cement alkaline environment was hydrolyzed and consumed during hot water immersion at 90℃， which resulted in the formation of more pores larger than 200nm in the cement stone. The PVA-PLA fibers remain intact and plug with the cement stone at low temperature， and the fiber degradation at high temperature forms a channel inside the cement stone and unblocking， which can support the broken pore wall and at the same time， realize partial unblocking of geothermal wells under high temperature hydrothermal conditions.

Abstract:Traditional rate of penetration （ROP） prediction models have often been constrained by issues such as high data dimensionality and feature correlation， resulting in limited efficiency and accuracy of ROP prediction. To address these issues， a ROP prediction algorithm model based on particle swarm optimization （PSO） with integrated feature selection has been proposed in this paper. Based on data preprocessing， 3 key parameters， threshold_1， threshold_2， and threshold_3， have been chosen as optimization targets， and a fitness function has been constructed by combining historical data and the PSO algorithm， thereby establishing the ROP prediction model. Subsequently， the proposed ROP prediction method has been validated using actual drilling data and compared with traditional machine learning algorithm models. Experimental results show that the proposed PSO-based integrated feature selection algorithm achieves higher efficiency and accuracy in feature selection. Compared to before optimization， the accuracy of the 4 machine learning ROP prediction models trained using the optimized integrated feature selection results is improved by 59%， 1%， 3%， and 1%， respectively. Compared to models trained using all features， the accuracy has been improved by 24%， 2%， 4%， and 3%， respectively. This paper provides an effective feature selection method for cases where too many feature parameters have been extracted in drilling engineering. It offers significant guidance for the practical application of feature selection algorithms in the engineering field.

Abstract:In the present core drilling project， there are still some problems such as low core recovery rate and low coring efficiency in broken formations. In this paper， the broken strata are classified into hard broken， soft broken， brittle broken and loose broken according to the lithology and broken reasons. The problems of core erosion， blocking， grinding and loss are analyzed. It is thought that the main reasons to coring problems in broken areas are as follows， in the hard broken strata， the core tube is blocked due to the core broken and vollume increase， in the loss broken strata， the drilling fluid erodes the cores， which both exist in the soft broken and brittle broken strata， moreover， it is not easy to be discovered because of the high drilling speed. The contermeasures are as follows： coring technology of low WOB， low RPM， low pump pressure and high performance water-based polymer drilling fluid， anti-erosion core bit， compound core claw， and double pipe single action wireline coring tool. The relevant technology was applied in ZG1 coal seam coring in Songjiaying south comprehensive gas survey， Tangshan City， Hebei Province， and the core recovery rate in the coal seam was reached to 98.77%， which has certain referential value to core drilling in similar strata.

Abstract:A wide range of fracture zones and water-rich areas commonly exist along the axis of the tunnel in the long and deep buried tunnels of water conservancy projects， the management of pre-grouting by more than 1000 meters of ground horizontal directional drilling can achieve a good effect of the surrounding rock reinforcement and gushing water blocking， which has been a successful attempt in the water conservancy industry. This paper introduces the successful experience of drilling ultra-long horizontal directional pre-grouting holes with screw drilling tools in a project. The difficulties and problems are discussed such as cutting removal， coping with the problem of “back pressure”， measurement while drilling system in strong magnetic field， measures of green exploration， as well as the insufficient adaptability of drill， low efficiency of hard-rock drilling， and the influence of grouting on drilling operation， etc.， and the contermeasures are also posed. 4 main holes and 6 branch holes were constructed， along which the longest hole is 1427m， and the drilling workload is 8737.89m. The implementation of the project proves that the current directional drilling technology has the ability to drill accurately over long distances， which can provide a guarantee for the pre-grouting and ahead-treatment in the complex strata of the ultra-long tunnels and the related drilling projects.